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FixedWing
06-06-2004, 07:12 PM
I want to say hello. I?ve been monitoring SuperCub.Org for quite a while now and have quite enjoyed it. I especially love all of the great photos in the photos section!

I?m posting now because I?ve decided to build a Super Cub in the Experimental category. The goal will be maximum STOL performance which will mean light weight, good power and a high performance wing. I am also looking for maximum utility so multiple landing gears (tundra tyres, skis and floats). I?m leaning towards VFR but also want to look at whether IFR can be done today without too much of a weight penalty.

So here is my immediate question: I?ve read about the upcoming ATP Turbine engine:

http://www.atpcoinc.com/

And I read the discussion of it here:

http://www.supercub.org/phpBB2/viewtopic.php?t=3850

At first blush this seems an ideal engine for an experimental Super Cub (light, powerful, cheap, reliable). But the more I think about it the more I see some big problems:

1) When you fly a Super Cub you often need very quick applications of power. For example, to arrest the sink rate when coming in for a landing over an obstacle at minimum controllable airspeed. I really have my doubts whether a turbine engine can ever provide this quick goosing of power.

2) Turbine engines need careful monitoring. You really need to pay attention to the power settings to avoid overpowering the engine. There isn?t the obvious feedback you get on a reciprocating engine. With a reciprocating engine, you can basically just shove in the power and go. A turbine will just give more and more power until it destroys itself. I?m not sure a short field takeoff over an obstacle in a single-pilot aircraft is exactly the right situation for this sort of careful monitoring of the power setting.

I can imagine that technology could take care of the second problem but what about the first? Is the power availability quick enough on these engines to do the job? Or possibly are the weight savings and performance advantages enough with a turbine engine to justify putting up with these problems?

Curious what others think???

Stephen

Fortysix12
06-06-2004, 08:34 PM
What's it like on Mars? As far as the turbine goes Do you like the smell of raw jet fuel? I don't. I spill gas once in a while when I'm fueling the cub and it goes right down into thewing -no big deal,but jet fuel is another story. Take the same money and tweak a 180 or better yet build your plane with a 150 then after you know what there is to know about your new plane convert to jet. That will give the turbine guys time to get there stuff and kit ready. That's only if you like the smell of jet fuel. turbine is novel but for the cub it's not for me.

AlaskaAV
06-06-2004, 08:48 PM
Stephen

Needless to say I have no knowledge about flying a turbine powered Super Cub but can pass on some thoughts about flying the P&W powered PC6 Porter.

First of all, a turbine engine, even the APU type used for the Super Cubs, are really not inexpensive. Maintenance costs are less until engine change.

When flying an aircraft with the turbine engine out front, you really get so you notice the audio at any given power setting. A person gets to understand both the engine and prop sounds real fast. Both prop and power levers on the Porter are next to each other and controlled by one hand at the same time and I would assume that would be the same in a Super Cub. Actually, I found that you can really get just as rapid power response from a turbine prop as you can with a recip prop most of the time. Power (RPM) is always maintained and than all it takes is changing the prop position. That is where a turbo prop differs from the jets on commercial airliners. I probably am not saying all this right but that is what it amounts to. Just prior to landing, power is brought back up (spooled up) and than go into ground fine setting (or more but never bata) for the prop with the same rpm setting for the engine. Talk about a speed brake. Need more power, change the prop setting, it will lay you back in the seat real fast.

What I know about flying the turbine Porter came from one of our company pilots from Kotzebue who knew everything that the Porter could do, inside and out. He did a vertical dive one time and we never got over 90 knots. What a weird feeling. All he did was put in a little bata (reverse prop) like trying to back up. Book says never to do that but what that the heck, he said he never learned how to read in school anyway. :wink:

Our Twin Otter pilots flew those aircraft, engine wise, far different than the Porter pilots did although the same basic engine, just different situations. Some of our Porter pilots may have not always understood these things.

http://www.supercub.org/gallery/view_photo.php?set_albumName=album87&id=aad

From what I have read, the turbine powered Super Cub would really be something to fly. Poor man's Porter? Those APU engines have a long history of maintenance free operations.

As with a recip engine, fuel controls the RPM of an engine and it is the same with a turbine. There is a max setting you can obtain, usually around 110% of designed limits. The N1 temperatures (operating temperatures) will go into the red real fast at that setting. Red is a no-no of course. Usually for a turbine, 90% more or less, is the normal power setting for take off. Higher if weight requires say to 93% but 98% is too normally too high. Still, to clear that 50 foot tree, you might still have 10% more power available for a few seconds without hurting the engine although it does take a second or two to spool that up. When the temps get too hot in a turbine, pulling the power back cuts back on the fuel and instant reduction in temperatures without a sudden loss in power. Gee, hope I said that right. When making a take off, just a millisecond to denote the color of the power gauge is all it takes to control power. Forget the numbers if need be, if it is red, pull the power back a fraction. Does not really distract from controlling the aircraft. Just something to get used to but normal once you have learned it.

Never any carb ice either. Word of caution, the steady sound of a turbine tends to lull a person into a dozing mode at times. Not like the hiccup from a recip to wake you up. :sleeping:

Keep in mind also that there is very little if any preheating needed on a turbine. Stick the heater hose under the panel and warm up the instruments and radios instead. Keep right on flying beyond 40 below zero if necessary. Just think of the cost savings too. No oil changes, jet fuel costs less than av gas. No muffler repairs and talk about no vibrations. Wow. :boohoo

I suspect you could do the same thing with a turbine powered Super Cub that can be done with the Porter. Hang it on a prop just right and it will not stall but just mush forward at about 5 knots. What a feeling that is.

I had a friend from Ruby, Alaska that flew turbine powered DC-3s for a while. What an aircraft really but just not right for his operation. He was even sent a tri turbine powered 3 to tryout for a while at no charge.
If a turbine powered DC-3 is good, so would a Super Cub.

Hope this might give you some more ideas for questions.

Phil Kite
06-06-2004, 10:52 PM
Can't recall what the atmosphere is like on mars, maybe rocket power would be more suitable for you? This nut-job should be able to help you out http://www.rocketguy.com/oldhome.html[/url]

FixedWing
06-07-2004, 03:43 AM
Can't recall what the atmosphere is like on mars, maybe rocket power would be more suitable for you? This nut-job should be able to help you out http://www.rocketguy.com/oldhome.html[/url]

Alas, I gave up on visiting Earth long ago. No intelligent life present. :roll:

Sorry guys. ?Mars? is just a habit I picked up from posting on some of the car related boards. Sometimes it isn?t a good idea to let people know where nice cars are located. They vanish with much greater regularity than do Super Cubs. :(

I travel a lot. I?m currently in Connecticut though soon I will be in Europe. My home is actually Hongkong. So Mars isn?t that far from being accurate. :)

Stephen

FixedWing
06-07-2004, 04:18 AM
As far as the turbine goes Do you like the smell of raw jet fuel? I don't. I spill gas once in a while when I'm fueling the cub and it goes right down into thewing -no big deal,but jet fuel is another story. Take the same money and tweak a 180 or better yet build your plane with a 150 then after you know what there is to know about your new plane convert to jet. That will give the turbine guys time to get there stuff and kit ready. That's only if you like the smell of jet fuel. turbine is novel but for the cub it's not for me.

I love the smell of Jet A in the morning! :-D

Seriously though, a turbine has a reciprocating engine beat in every way when it comes to fuel.

100LL is unreliable at this point because of the lead issue and the fact that there is only a single supplier for the additive today. Elsewhere in the world, you often need to arrange 100LL to be delivered in 55 gallon drums. On the other hand, Jet A is available absolutely everywhere that commercial jets fly.

Jet A is often much cheaper than 100LL in the rest of the world.

Auto fuel can only be used in certain engines. If using auto fuel in an aircraft is a criteria then this restricts which engines may be used. If I were to use a reciprocating engine then I would want to be able to use auto fuel so as to not to be subject to 100LL availability issues.

One of the things I?m considering on the design is how quickly and easily the aircraft can be broken down to its component parts, put in a shipping container and then reassembled in some third-world country using the available resources there.

Then the advantage of a turbine engine on an Experimental category aircraft are even greater. You can burn absolutely anything in it including auto diesel and even untaxed home heating oil.

The only down side seems to be the additional fuel that a turbine will burn and the need to carry this. But the engine weighs less and I suspect this will offset any additional weight required for the fuel (which is only necessary in any case for a long trip).

As for starting with a reciprocating engine and then converting to a turbine later, the weights of the engines will be different so the weight and balance different. Hanging the engine further off the front might not be ideal for visibility reasons. So if the aircraft was designed initially to take the turbine it might be possible to design it to reduce this overhang. Also, there will be different instrumentation and fuel needs for the two versions. So I don?t think it makes sense to start with a reciprocating engine and convert later.

Stephen

FixedWing
06-07-2004, 04:36 AM
Needless to say I have no knowledge about flying a turbine powered Super Cub but can pass on some thoughts about flying the P&W powered PC6 Porter.

Wow Earnie, thanx for the great post! Just reading what you say gives me goose bumps. If a Super Cub can be made to do what you say then it would be a pretty incredible flying machine. In fact, I would think even more so than the Porter due to the lower weight and therefore the quicker reaction of the aircraft to power changes.

Though it is also pretty obvious that the operator would need to learn a bunch of different procedures to really take advantage of the turbine. That should be a challenge. Also, I get the impression that it would be a lot easier to really f**k up.

But lots of smooth power, available anytime, available even at altitude, available even in the super cold, these seem to be the stuff of Super Cub fantasy. This definitely seems to be the way to go. :-)

Stephen

AlaskaAV
06-07-2004, 05:29 AM
Needless to say I have no knowledge about flying a turbine powered Super Cub but can pass on some thoughts about flying the P&W powered PC6 Porter.

Wow Earnie, thanx for the great post! Just reading what you say gives me goose bumps. If a Super Cub can be made to do what you say then it would be a pretty incredible flying machine. In fact, I would think even more so than the Porter due to the lower weight and therefore the quicker reaction of the aircraft to power changes.

Though it is also pretty obvious that the operator would need to learn a bunch of different procedures to really take advantage of the turbine. That should be a challenge. Also, I get the impression that it would be a lot easier to really f**k up.

But lots of smooth power, available anytime, available even at altitude, available even in the super cold, these seem to be the stuff of Super Cub fantasy. This definitely seems to be the way to go. :-)

Stephen

Not as much difference than you might expect. The Porter has around 600 shaft horsepower and am not sure what the turbines for the Cubs come out at but suspect, pound to horsepower, they will be about the same. It all goes back to hp. If a turbine Cub had a turbine engine that produces only 180 hp, it will perform much the same as a recip I would think. My experience with the Porter was just after they started building them. Wien Porters started with S/N in the 50s. We had both a recip and turbine Porters and the recip was almost useless as far as I was concerned. Way under powered.
We had one Porter on amphib floats and what an aircraft properly flown. Really nice backing it up on a beach (and hope the pilot didn't forget to lift the water rudders). Full reverse props are great unless too much power is applied to back up and if that happens, it dunks the engine and prop right into the water immediately. Bye bye engine. It only happens once per pilot though.

Once a person gets checked out on turbine power, there would not really be that much difference than a recip Super Cub I would think. With either one, when you get to that bunch of trees on the departure end of the runway, it will climb like a homesick angle so to speak.

To get a good idea how far forward the engine has to be mounted on a Cub modification, take a look at the turbine modification of the Beaver and Otter. One good thing is the extra baggage compartment located behind the engine and in front of the firewall which helps on w&b.

Contrary to some comments, a person must be rather careful about the fuel that is used. They will burn regular gas of course but at a given number of hours (which is rather low), the engine has to be pulled apart and inspected. It all goes back to temperatures and sulfur content. Diesel has way too much sulfur and JP-4 is too hot. Jet A-1 and A-50 works good and probably some newer blends that I am not aware of.

I know one thing, I would love to take the stick on a turbine powered Cub.

FixedWing
06-07-2004, 10:27 AM
The Porter has around 600 shaft horsepower and am not sure what the turbines for the Cubs come out at but suspect, pound to horsepower, they will be about the same. It all goes back to hp. If a turbine Cub had a turbine engine that produces only 180 hp, it will perform much the same as a recip I would think.

The specific turbine engine i'm looking at is the ATP (Affordable Turbine Power) 6.5. The developer quotes:


Model 6.5 is a radial turbine in conjunction with a compound planetary gearbox. It has ram air induction and electronic fuel injection system. The Model 6.5 maintains static thrust using a NSI cap 140 propeller. The engine is capable of on-demand HP ranging from 120 HP to 240 HP. The Model 6.5 is available in a pusher or a tractor configuration. It's dimensions are : 32" in length to prop flange, 12 1/2" in diameter at the hot section and 10" diameter at the gear box, 16" in height at the accessory pad on the gear box. The Model 6.5 will burn JetA, Kerosene, Diesel and Gasoline, with JetA and Kerosene being the preferred fuel.

http://www.atpcoinc.com/Pages/Products.html

So the available power exceeds that on almost any reciprocating Super Cub currently out there. Combine that with the under 200 lb. weight which should allow a lighter Super Cub for what should be top STOL performance!

Elsewhere I have read that they are quoting an intial cost of US$35K and a TBO of 5000 hours with a overhaul cost of $7,500 so this also beats a reciprocating engine. Fuel flow also looks good with 10.7 gph at 120 bhp which is the power I would guess would be needed to cruise a Super Cub.

Availability is said to be for AirVenture / Oshkosh 2004.

Here is a photo:

http://www.atpcoinc.com/photos/photo_01.jpg

Stephen

AlaskaAV
06-07-2004, 12:57 PM
Those numbers look real good Stephen, especially the available hp.

When they say it will burn diesel, I suspect they refer to #1 diesel which is not always available except in the winter in the northern states. Arctic grade diesel in Alaska. Big rig truckers often have to run a fuel additive to keep even #1 from jelling in the winter. I suspect the engine manufacturer would really frown on using that additive.

FixedWing
06-07-2004, 03:28 PM
Those numbers look real good Stephen, especially the available hp.

When they say it will burn diesel, I suspect they refer to #1 diesel which is not always available except in the winter in the northern states. Arctic grade diesel in Alaska. Big rig truckers often have to run a fuel additive to keep even #1 from jelling in the winter. I suspect the engine manufacturer would really frown on using that additive.

I agree completely. The numbers all look excellent. And now after hearing your comments I feel a lot better about the idea of operating one in a Super Cub.

I'm not too concerned about whether I need to operate JetA or can use auto diesel. Already JetA represents a savings over 100LL. And in fact, in Europe and many other places the savings can be even more dramatic as JetA is considered "international" fuel for airlines (therefore not taxed just as export booze is considered duty-free and not taxed) whereas 100LL is heavily taxes (domestic fuel for playboys).

The appeal is that in a push it will burn just about anything -- even gasoline. This is quite a feature for an airplane that you want to be able to use in unusual places. Since it will be the exception rather than the rule, I don't think the reduced life of the engine will be that big of a consideration.

Anyway, here is another interesting photo I came across which shows the ATP mounted to a Super Cub. Not a lot of room actually behind the engine:

http://www.pilotlist.org/balades/oshkosh/TN_stand02.JPG (http://www.pilotlist.org/balades/oshkosh/stand02.JPG)

[Photo credit: http://www.pilotlist.org/balades/oshkosh/stand_01.htm -- click on photo for full-sized version.]

Things certainly are becoming more exciting in general aviation. :)

Stephen

AlaskaAV
06-07-2004, 04:00 PM
If you look real close, you will notice that with a cawling on, it will narrow down a lot near the prop. Helps cut down on drag but also helps during taxing. I really like the way the installation went in the photo. Nice and clean.

At one point in the 60s, I asked our Porter pilot (the one that taught me how to fly the Porter) for a minimum fuel flight to a town some 15 or so miles away so I could move a big backlog of mail. He took it with fuel on board. Once he got upstairs, big deal, probably 500 foot or less (he liked to fly low so he could count the sheefish in the Kobuk River enroute), he noticed the gauges were showing a little less fuel than he thought he had. Upon landing at Shungnak and offloading, he bought and paid for 5 gal of car gas just in case. He said it made him feel a little better getting back to our airport. Since it only involved just a few minutes and it was mixed probably 50% with jet fuel, it didn't require a report to maintenance.

I envy you. I would really enjoy being around a project like what you are looking at. Kind of like when I built up a big bad Chevy engine for a 1929 Ford roadster and raced it at the airbase in Lincoln, Ne back in the mid 50s.

:cheers

FixedWing
06-07-2004, 04:29 PM
If you look real close, you will notice that with a cawling on, it will narrow down a lot near the prop. Helps cut down on drag but also helps during taxing. I really like the way the installation went in the photo. Nice and clean.

At one point in the 60s, I asked our Porter pilot (the one that taught me how to fly the Porter) for a minimum fuel flight to a town some 15 or so miles away so I could move a big backlog of mail. He took it with fuel on board. Once he got upstairs, big deal, probably 500 foot or less (he liked to fly low so he could count the sheefish in the Kobuk River enroute), he noticed the gauges were showing a little less fuel than he thought he had. Upon landing at Shungnak and offloading, he bought and paid for 5 gal of car gas just in case. He said it made him feel a little better getting back to our airport. Since it only involved just a few minutes and it was mixed probably 50% with jet fuel, it didn't require a report to maintenance.

I envy you. I would really enjoy being around a project like what you are looking at. Kind of like when I built up a big bad Chevy engine for a 1929 Ford roadster and raced it at the airbase in Lincoln, Ne back in the mid 50s.

You are totally correct about the cowling. Take a look at this photo of an RV-4 (or is it an 8?) with the ATP engine:

http://gallery.rennlist.com/albums/album86/Dsc00003.jpg

Now, the RV is hardly a big aircraft!

You are right about the goal. Part of it is exactly as I said, to have an aircraft which can be operated just about anywhere in the world. I really do intend to take it to places like Australia, Africa, Asia, etc. But the other part is about building ultimate hard-core machine -- just like your bad-ass 1929 roadster. :)

Stephen

AlaskaAV
06-07-2004, 06:19 PM
Hey, I trashed a Chrysler Hemi powered T pickup with my good old home built Chevy the first time out on the drag strip at Lincoln. Eight thousand + RPM. Not bad for a 304 inch chev and I was working it for sure. Just had to beat that hemi because the Hemi driver knew he had me beat but I knew better. The butterflies got to me after the race and far worse than after my first solo with the J-3.

I suppose it would be fun to take a bird like you are thinking of all over the world but don't forget, you have the best country in the whole world right next door, Canada and Alaska, let alone the areas of the continental US. Well, maybe the Andes in South America would be interesting but make sure you have O2. It would take a lifetime just to explore those areas.
An airstrip just about anywhere you want to land. Stick a small mountain tent and mountain climbing survival equipment in the back along with some dehydrated food (tastes good now days) and a can or two of gel alcohol fuel to warm things up with and some water purification tablets and when you get into the mountains, you will never want to leave. Oh yes, don't forget the fishing equipment (but no firearms) and an old, well oiled cast iron frying pan, the kind that a spouse hits the other spouse with when they have been bad as seen on TV. :wink: All the animals (except bears, moose and elk) and especially the wolverine, will be just as curious about you as you are about them and with the right motions and sounds, you will become friends in no time. Been there, done that. Only thing better is sex I suppose. :oops: By the way, did I mention that a proper copilot is a must?

Ah, aviation, the only way to fly (or live).

FixedWing
06-08-2004, 01:55 PM
I suppose it would be fun to take a bird like you are thinking of all over the world but don't forget, you have the best country in the whole world right next door, Canada and Alaska, let alone the areas of the continental US. Well, maybe the Andes in South America would be interesting but make sure you have O2. It would take a lifetime just to explore those areas.
An airstrip just about anywhere you want to land. Stick a small mountain tent and mountain climbing survival equipment in the back along with some dehydrated food (tastes good now days) and a can or two of gel alcohol fuel to warm things up with and some water purification tablets and when you get into the mountains, you will never want to leave. Oh yes, don't forget the fishing equipment (but no firearms) and an old, well oiled cast iron frying pan, the kind that a spouse hits the other spouse with when they have been bad as seen on TV. :wink: All the animals (except bears, moose and elk) and especially the wolverine, will be just as curious about you as you are about them and with the right motions and sounds, you will become friends in no time. Been there, done that. Only thing better is sex I suppose. :oops: By the way, did I mention that a proper copilot is a must?

Ah, aviation, the only way to fly (or live).

I totally agree with everything you say and especially with your comments about exploring one's backyard first.

Thanx Ernie for all of the great input! It has cleared up a lot of doubts for me.

Thought one more photo might be useful. This is the front of the RV-4 with the ATP turbine. It really makes your point about the frontal area being so small!

http://gallery.rennlist.com/albums/album86/New_Air_Intake.jpg

Stephen

Longwinglover
06-08-2004, 06:12 PM
This is a J3 airframe but it will give n idea of thenose shape and length.

http://groups.yahoo.com/group/piper-cub-builders/files/Turbo-Prop/

People have said turbines were the way of the future...

John Scott

Longwinglover
06-08-2004, 06:14 PM
OOps....it requires a password to view. I'll try to post another way.

John Scott

FixedWing
06-08-2004, 06:24 PM
This is a J3 airframe but it will give n idea of thenose shape and length.

http://groups.yahoo.com/group/piper-cub-builders/files/Turbo-Prop/

People have said turbines were the way of the future...

John Scott

I post this photo totally without comment. :crazyeyes:

http://gallery.rennlist.com/albums/album86/Dsc00002.jpg

Stephen

Phil Kite
06-08-2004, 07:53 PM
I can maybe understand a turbine on a 18 or a 12, but on a J-3?? :crazyeyes:

Greg Smith
06-09-2004, 09:45 AM
I think they're pulling our leg. Looks like butcher paper. :roll:

FixedWing
06-09-2004, 12:14 PM
I think they're pulling our leg. Looks like butcher paper. :roll:

Yes, but very nicely formed butcher's paper. :lol:

http://gallery.rennlist.com/albums/album86/Dsc00001.jpg

Stephen

CrossedControls
06-09-2004, 05:22 PM
The picture you showed further up the page looks like the Smith Aviation Xp Supercub. Here's another picture (from Sun N Fun this year)

http://www.strip.flyer.co.uk/pics/IMG_1057_small.JPG (http://www.strip.flyer.co.uk/pics/IMG_1057.jpg)

Pete

FixedWing
06-09-2004, 05:53 PM
The picture you showed further up the page looks like the Smith Aviation Xp Supercub. Here's another picture (from Sun N Fun this year)...

The photo I posted was supposedly taken at Oshkosh 2003.

The prop in the earlier photo seems to be a variable pitch prop. But the prop on your photo seems to not be variable pitch. Is it just a mock-up? I would think a turbine engine must use a variable pitch prop.

Stephen

AlaskaAV
06-09-2004, 06:40 PM
The picture you showed further up the page looks like the Smith Aviation Xp Supercub. Here's another picture (from Sun N Fun this year)...

The photo I posted was supposedly taken at Oshkosh 2003.

The prop in the earlier photo seems to be a variable pitch prop. But the prop on your photo seems to not be variable pitch. Is it just a mock-up? I would think a turbine engine must use a variable pitch prop.

Stephen

It has to a variable pitch prop otherwise it would be almost impossible to fly at slow speeds. It has to keep the engine rpm up because it would take too long to spool up in an emergency (every landing). Even a full jet such as a 737 spools up maybe 25 per cent prior to the "fence" for the same reason. A turbo prop on a small aircraft is really great and as I have said before, I would love to fly a turbine powered Cub. What a pleasure that would be.

It was interesting with the P&W powered Porters where a person can hold a prop blade while the pilot spins it up and lights it up. It will actually bend the prop blade but still in place. It has to be released soon so the hub end of the prop can shove some cooling air around the engine or it will get too hot very fast.

The P&W powered Porters were always shut down in feathered position while the Astazou powered were shut down in ground fine just as the Garrets were on the Skyvans. Just the way those engines were designed.

Greg Smith
06-10-2004, 08:13 AM
Look at the pitch on the fixed pitch prop above... Which direction is the engine going to turn it? Also, it looks like it is on backwards. The planform shown at the prop tip shows the cambered side to the rear...

Longwinglover
06-10-2004, 08:28 AM
Don't you know that a TURBINE powered Super Cub will have such incredable performance that it will be able to fly BACKWARDS!!??!!

In calm wind and tailwind (up to 150kts) conditions!

John Scott

FixedWing
06-10-2004, 10:10 AM
Look at the pitch on the fixed pitch prop above... Which direction is the engine going to turn it? Also, it looks like it is on backwards. The planform shown at the prop tip shows the cambered side to the rear...

Which is why I thought it was just a mock-up to make for a better display. Guys like looking at big props. :wink:

Stephen

CrossedControls
06-10-2004, 04:47 PM
My picture of the Smith Cub had the ATP turbine, don't know about the prop. Here is a pic taken at Osh 2003. The ATP turbine guys had a booth alongside Smith Aviation. Send Nick Smith an e-mail I'm sure he would fill you in with all the details.

http://www.supercub.org/albums/Petespics/aar.thumb.jpg (http://www.supercub.org/gallery/view_photo.php?set_albumName=Petespics&id=aar)


Pete

Jacob Papp
06-12-2004, 02:14 PM
check out the 368kb video in this link.

http://www.atpcoinc.com/Pages/Requests.html

I dont think this power plant will have trouble spooling up quick enough.
:o

FixedWing
06-12-2004, 02:28 PM
check out the 368kb video in this link.

http://www.atpcoinc.com/Pages/Requests.html

I dont think this power plant will have trouble spooling up quick enough.
:o

Yes, I saw that video. Pretty impressive. Can you imagine a Cub making a sound like that in some valley or on a small pond somewhere? Hmmm... music to our ears but I wonder if everyone will appreciate it? It might not be a good thing if too many of these turbine Super Cubs are around. In fact, I wonder if noise will be an issue?

As for the spool-up, I would think zero-load would be one thing, but how quickly will it spool up with a load? If you watch the fuel flow figures it takes a little while before those go up. I would think that is an indication of the load they are putting on the engine.

Still, it sounds like one of the design criteria for this engine is quick spool-up. I'll be very interested to hear the results once these engines are in the hands of end-users who can report their findings.

Stephen

Bill Rusk
06-12-2004, 09:33 PM
I don't mean to rain on the parade, but I sincerely believe in my heart that the turbine Cubs will have some pretty serious stability problems about the vertical axis, ie in Yaw. You already get a little of that issue on floats, look at all the planes that require extra (or larger) vertical stabilizers when on floats. If you really want this to work well, it seems that you would want the nose arm to remain the same or you would need to lengthen the tail arm. I may be way off base but in general if it doesn't look right it won't fly right and a long snout just looks wrong to me. Some of you guys with turbine Beaver or Otter time jump right in here and straighten me out. Did they have to change anything on those planes after the turbine conversion?

Respectively submitted....

Bill

Crash
06-13-2004, 11:54 PM
Looking at their web site I noticed the engine had to turn up to 3050 RPM to get 600 lbs of thrust. I remember one of the Cub guys on a previous post was getting 580 lbs of pull or call it thrust out of a 180 hp Cub. The difference was the turbine is drinking 16.6 gallons per hour at 3050 RPM. Crash

Ursa Major
06-14-2004, 12:03 AM
Some of you guys with turbine Beaver or Otter time jump right in here and straighten me out. Did they have to change anything on those planes after the turbine conversion?

Respectively submitted....

Bill

Seems like every turbine beaver I've seen has had a substantially larger tail installed as a part of the conversion.

AlaskaAV
06-14-2004, 12:07 AM
Looking at their web site I noticed the engine had to turn up to 3050 RPM to get 600 lbs of thrust. I remember one of the Cub guys on a previous post was getting 580 lbs of pull or call it thrust out of a 180 hp Cub. The difference was the turbine is drinking 16.6 gallons per hour at 3050 RPM. Crash

Just a comment Crash

What you are quoting is what fuel that might be consumed in about the first 60 seconds on takeoff, not at cruise. Again, I am not that aware of the turbine powerplants suitable for the Cubs, only what what we flew on the Porters. As I recall, the porters ran much higher than 3050 on takeoff and lower inflight. Needless to say, I could be wrong since it has been many years.

CptKelly
06-25-2004, 07:49 PM
The way I understand it, the ATP Turbine only has a prop control to control the thrust, NO THROTTLE CONTROL. This engine runs at 100% N1 all the time, continuously. Its fuel control is automatic, and varies itself according to how much thrust one decides to dial in. However, no beta range or reverse is provided, all one can get is zero thrust. This setup gives instant thrust on demand-which is good, however, on landing, this gives very little engine drag. I view this as fine on takeoff, but on landing, one better be really careful and practiced due to the loss of engine drag. Look before you leap. If I am incorrect, someone please correct me.

PT6 Lover,

Mike in NC

AlaskaAV
06-25-2004, 08:20 PM
The way I understand it, the ATP Turbine only has a prop control to control the thrust, NO THROTTLE CONTROL. This engine runs at 100% N1 all the time, continuously. Its fuel control is automatic, and varies itself according to how much thrust one decides to dial in. However, no beta range or reverse is provided, all one can get is zero thrust. This setup gives instant thrust on demand-which is good, however, on landing, this gives very little engine drag. I view this as fine on takeoff, but on landing, one better be really careful and practiced due to the loss of engine drag. Look before you leap. If I am incorrect, someone please correct me.

PT6 Lover,

Mike in NC

Probably true Mike. I understand the basic engine is an APU engine and that is the way they operate. I agree on the prop control for instant thrust since it saves the time for spool up. That was hard to get used to on the Porters.
It surprises me that there is no beta though. What a loss. That reverse on our Porters, wheel or float, was a great help and needless to say on the Twin Otters.
I look forward to reading more from those that work around that turbine. All new since I left aviation.

CptKelly
06-25-2004, 10:57 PM
Ernie,
We used beta range and reverse everytime we made a landing. The reverse feature on our U-21's would cut our landing roll quite significantly. This effectively made our KingAir clones, a pea patch plane, as well as a 250 knot traveler. We didn't have any problems landing on dirt strips shorter than 2000 feet, and we could leave that strip, at gross or worse, every time. This was all in a war zone, SE Asia.
I am not certain why reverse wasn't integrated in the ATP engine prop. Looks like it would be much more effective if beta/reverse was available.

Mike

AlaskaAV
06-26-2004, 10:56 AM
Ernie,
We used beta range and reverse everytime we made a landing. The reverse feature on our U-21's would cut our landing roll quite significantly. This effectively made our KingAir clones, a pea patch plane, as well as a 250 knot traveler. We didn't have any problems landing on dirt strips shorter than 2000 feet, and we could leave that strip, at gross or worse, every time. This was all in a war zone, SE Asia.
I am not certain why reverse wasn't integrated in the ATP engine prop. Looks like it would be much more effective if beta/reverse was available.

Mike

I am not that familiar with the U-21s Mike but they can't be much different than the Bandeirante 110s we flew many years ago. Talk about a fast aircraft also and not really all that good on short field but we didn't need that on most flights anyway. Passengers loved them.

I figured the ATP would have the reverse prop and it sure looked like it in the photos but than again, I am not familiar with the engine other than in an APU and even than, not all that much. When over the fence in a PT6 Porter, the N1 would be brought up to say 80 % and the prop power cut back. The prop would change pitch a lot faster than the PT6 would spool up so more or less, instant power. Come in at ground fine on a three point and once it felt right, full reverse and I mean that bird would stop on a dime and give a nickel's change. Better never try it with a main gear landing though. :cry: We were also French Astazou powered, which flew a lot different from the PT6s, as well as one recip, 09Z, a useless aircraft really, way underpowered. Needless to say, our Twin Otters were PT6 and our Sky Vans were Garrett Air Research which was flown different although I never flew one but rode in many.

When I saw the article about the turbine powered Super Cub, I started thinking of an aircraft like SJ's, and a beautiful one it is, on amphib floats and how great a turbine would be there. That is assuming the prop was full reverse of course. Talk about easy to dock. We had one PT6 powered Porter on amphib floats that we used in the Katmai area out of King Salmon, Alaska. Taxi up to a beach at a remote fishing camp, turn it around, pull the water rudders and just back it up to the beach. As you increased the power to back up once at the shore line, you could power lift the tail up enough to get several feet up on shore. Never any damage to the floats but there may have been a plate installed on the back bottom of the floats though, not sure. Time to leave? Passengers step from dry beach onto the floats (the aircraft will not rock because of ground support so less chance of someone falling off), board the aircraft and off you go. One person could dock real easy even at a dock and that is a 10 passenger aircraft or at least ours were.

I have mentioned it before elsewhere but the thing that really got to me when I first started working with the Porters, one of our pilots took it up to 7,000 AGL over a 4700 foot runway at Dahl Creek on a downwind at mid field. By the way, Dahl Creek was uncontroled so please don't try this at home. He never went past the other end of the runway and never got over 90 knots in a vertical dive and only made one 180 degree turn and landed half way down the runway. I watched his use of beta in that dive and what an odd feeling. He would pull it in and out to show me the difference and how the aircraft would react. By the way, did I mention the operator's manual said not to do that in flight? I have to admit though that this Porter pilot was probably the best natural light aircraft pilot I have ever met or flown with. Kotzebue will know who I am talking about. He was the one that taught me the ins and outs of flying the aircraft. I have seen this pilot land and stop an empty Porter in about 100 foot and lift off in less than 200 foot, once with the Governor (who was a pilot himself) of Alaska on board and at Dahl Creek. Of course that 650 shp out front really helps. :wink:

Picture coming in on final in a Super Cub, turbine powered say at 85% N1 with just enough prop to hold a steady airspeed, over 100 foot trees and at normal fence speed. Once clear of the trees, drop the nose real fast, crank in just a touch of beta to hold speed back until ready to flare and than increase power and you bring the nose back up at stall speed but under power and set it down three point and immediately go into beta again and since you were already at 85% and on a 2000 foot runway, you sill might have 1500 foot left. Well, gee, a guy can dream can't he? Bush flying in a turbo Super Cub, a pilots dream, right?

FixedWing
07-01-2004, 09:22 AM
The way I understand it, the ATP Turbine only has a prop control to control the thrust, NO THROTTLE CONTROL. This engine runs at 100% N1 all the time, continuously. Its fuel control is automatic, and varies itself according to how much thrust one decides to dial in. However, no beta range or reverse is provided, all one can get is zero thrust. This setup gives instant thrust on demand-which is good, however, on landing, this gives very little engine drag. I view this as fine on takeoff, but on landing, one better be really careful and practiced due to the loss of engine drag. Look before you leap. If I am incorrect, someone please correct me.


I really, really hope you are wrong Mike. Taking beta away from a turbine really robs it of so much that would make it so great for a Super Cub.

And I don't really understand what the advantage would be to their going this route? Surely it is just a matter of the ability of the prop to go into reverse position? That should be easy enough to do.

I agree, we are going to need a lot more details about this engine before we can commit.

Query if there are any other turbine engines out there that might be suitable for this application?

Stephen

Bill Rusk
07-01-2004, 05:50 PM
When I went to get the wings I saw the turbine. Looks good. Nick Smith Sr was also involved in the prop design. The warp drive unit did not work. He says the first turbine cub should fly before Oshkosh. They were going to try to get it to the show but don't think all the paper work will be done by then. He does not think stability will be a problem.
Should be interesting.

Bill

Bugs66
08-17-2004, 11:23 PM
When I went to get the wings I saw the turbine. Looks good. Nick Smith Sr was also involved in the prop design. The warp drive unit did not work. He says the first turbine cub should fly before Oshkosh. They were going to try to get it to the show but don't think all the paper work will be done by then. He does not think stability will be a problem.
Should be interesting.

Bill

Anyone have an update on this? My friend who is building an RV is pretty excited about development on their end. I have to admit salivating over a turbine Cub possibility. My own personal Porter would be very cool.

Bugs

geoffmeyer
08-22-2004, 06:17 PM
Stephen,

I'm also very interested in this engine. I've spoken a bit to the owner - charlie - at Innodyn. He says the engine will and does have reverse. If there is any question in your mind, check out the following link. It's a video of the RV on landing.

http://www.innodyn.com/aviation/action.html

The direct drive turbine is a great design for quick response. There is no reason it can't have reverse. The propeller changes pitch into a fine (or negative) pitch while the engine keeps turning at its high rpm. NSI will be offering a 79" 2 blade prop. There are several different reductions available: here is a cut from their webpage...

...Our Turbines are designed for output speeds of 2,000; 2,250; 2,500; 2,750; 3,000; and 3,600 RPM. We recommend the use of 2,750 RPM for fixed-wing aircraft applications....

The controls that will be used for the NSI CAP200 prop are electric. You control the prop blade angle while the FADEC fuel control unit meters fuel to keep the engine speed a constant. There are two engine speeds, and thus prop speed settings. High and low. The low setting is for ground operations and will keep the noise level down.

One thing to consider is the prop material. I think the NSI is a composite. Is a composite prop acceptable for back country use? Since the prop has to be a variable pitch & reverse capable to work with a turbine engine, I don't know if there are any good alternatives. I'd be curious to see what you've heard

G.

FixedWing
08-22-2004, 07:51 PM
I've spoken a bit to the owner - charlie - at Innodyn. He says the engine will and does have reverse.

I wrote to Innodyn asking these sorts of questions but never got a reply so this information is especially welcome. Thank you!

The videos also look quite impressive. I hadn't seen them before.

I really like your description of how the system operates. It really does seem idiot proof. That sort of meets some of the questions raised at the beginning of this thread about how difficult it would be to operate under the stress of STOL conditions. Sounds like it will be almost impossible to damage the engine.

What problems do you see in using a composite material prop?

One thought that comes to mind is the sound. I personally find it an enjoyable sound. But I wonder how loud it will be in real life and whether this sound will be appreciated? Ditto the smell.

I'm also wondering what the criteria might be for choosing different engine RPM's and why 2750 is recommended as ideal.

Stephen

geoffmeyer
08-22-2004, 09:15 PM
I'm not too sure it would be that idiot proof. Innodyn says the FADEC will control the fuel flow so that the engine won't exceed temperature limits. That will help from toasting the turbine. I'm not really sure how it would work if you dialed in too much of a prop pitch though. From what I understand, as you add prop pitch to a coarse setting, the prop & engine rpm will want to slow. The fuel control unit will add fuel to counter this action....what if you add too much pitch? Will the engine just slow down once its maxed out on fuel flow, or maybe the turbine temp will begin to rise & consequently, the FADEC will reduce fuel...? That's a question Innodyn could answer, but I haven't asked them yet.

I agree with the Pilatus PC6 guy - turbine operation is not something to be intimidated about. I think operating & learning the in's & out's of a turbo-charged or even normally aspirated piston is more difficult.

I hope someone else answers about the composite prop. I know nothing about props. I've heard that the best is an aluminum one because it can take abuse & then re-shaped -where the composite prop has a protective metal leading edge that is not so reshape-able?? - just a guess though.

I've operated the garrett engines & know how loud they can be on the ground & in the air. The reason is the prop is always spinning at a very high speed. Even when sitting still. I've asked Innodyn about this & they say the engine will run at a lower 1400rpm speed for ground operations. At that prop speed, there shouldn't be much noise.

I'd try to pick the lowest turning engine option, and put the largest diameter prop possible (with reasonable clearance). As of now, the largest prop they have for this engine is the 79" CAP200. At an engine rpm of 2750, the prop tip speed would be .86mach at 2000'msl & 50kts.

Sounds like you & I are interested in the same application of this engine. The majority of their interest is in the RV crowd. I'd be really thrilled to fly this engine if its what they say it is. Lets hope their supercub project proves to be a good performer!

G

mvivion
08-22-2004, 10:32 PM
Ernie,

Not sure about the French powered Porters, but the PT-6 Porter is flat rated at 550 hp, not 650. I suspect the Astazou engine is as well in that application.

As to the larger fins on the Turbine Beaver, note that the Wipaire Turbine Beaver uses the standard Beaver tail. The original deHavilland Turbo Beaver had a 30 inch long fuselage plug inserted into the fuselage to increase cabin volume, and get the engine out front for W & B purposes. With the longer fuselage forward of the center of lift, they then had to increase the size of the vertical tail to compensate. Wip didn't extend the forward fuselage, so increasing the tail wasn't required, and they used a 715 hp engine, I believe.

All this is to say that the size of the vertical tail on these airplanes was dictated by yaw stability, rather than power.

MTV

AlaskaAV
08-22-2004, 10:50 PM
Ernie,

Not sure about the French powered Porters, but the PT-6 Porter is flat rated at 550 hp, not 650. I suspect the Astazou engine is as well in that application.

As to the larger fins on the Turbine Beaver, note that the Wipaire Turbine Beaver uses the standard Beaver tail. The original deHavilland Turbo Beaver had a 30 inch long fuselage plug inserted into the fuselage to increase cabin volume, and get the engine out front for W & B purposes. With the longer fuselage forward of the center of lift, they then had to increase the size of the vertical tail to compensate. Wip didn't extend the forward fuselage, so increasing the tail wasn't required, and they used a 715 hp engine, I believe.

All this is to say that the size of the vertical tail on these airplanes was dictated by yaw stability, rather than power.

MTV

Needless to say I could be wrong and usually am but as I recall, the PC-6 Porters that we ordered with the PT-6 engines was a model that produced 650 shp but it has been almost 40 years. Side by side with the same load, the PT-6 powered Porters would out perform the Astazou hands down. Forget the one recip we had.
The performance of the turbine Beavers and Otters I have no personal knowledge about other than they are one heck of an aircraft.
One thing about a Porter: do not touch down tail wheel first or you will get several wrinkles in the fuselage just forward of the tail wheel.

CptKelly
08-22-2004, 11:02 PM
Guys,
The last thing I heard was that the ATP Turbine was going to be over $30.000, but could be $50000. The cost of the engine doesn't include the prop or spinner either. In order to get one, somebody's going to have to shell out a small fortune. My question is, is it worth it?

Mike

Bugs66
08-23-2004, 02:06 AM
Guys,
The last thing I heard was that the ATP Turbine was going to be over $30.000, but could be $50000. The cost of the engine doesn't include the prop or spinner either. In order to get one, somebody's going to have to shell out a small fortune. My question is, is it worth it?

Mike

The 185hp Innodyne is $28,500. True, you need to add prop, spinner but you also need to do this for Lyco-saurs. One thing to keep in mind is TBO is 5K. So you get two engines essentially, right?

It still begs the question of whether it's worth it. If I go Lycosaur for my experimental - with initial savings over turbine I can go buy a float kit probably. Of course if you have a love for turbines in general, who can put a price on that? :wink:

Bugs

FixedWing
08-23-2004, 07:11 AM
My question is, is it worth it?

In general, if it fulfills all of their promises then there is no question it is worth it.

But on some of the specifics I do have a cost issue. Innodyn has appointed Firewall Forward as their provider for mounting kits:

Rivers Aeronautical (http://www.riversaeronautical.com/)

The cost of this product seems to me to be quite high (their estimated price is US$12,500 on an RV aircraft). This significantly increases the cost of the engine and I am not sure what is really in these kits that justifies the price.

I also see a second, and maybe bigger problem. Rivers Aero is obviously going to concentrate on the RV series first. That will leave people such as us who are probably viewed as a niche part of the market out in the cold.

What I'm wondering is how many people can reasonably be expected to mate the Innodyn turbine to a Supercub? I am specifically wondering if it might make sense for us to form a group to develop a mounting kit for ourselves? This might be the cheapest and quickest alternative.

My personal feeling is that I want to actually have a Supercub in the air and get some sort of pilot report on how it flies before I commit to going the turbine route. But I am hoping that this will happen very soon. :)

Stephen

mvivion
08-23-2004, 10:30 AM
Wasn't it noted by the developer or someone on this site this spring that there was a Cub with the turbine on it either flying, or "imminently" flying? I remember making the gaffe on here of suggesting that the same turbine cub was at S N F this year as last, and the answer was that this was a different cub.

What happened to the one that had the engine mounted last year (2003) at Sun N Fun? Or is this a different engine conversion?

Just curious.

MTV

Junior
08-23-2004, 03:38 PM
Yeah a turbine engine can burn almost anything, even that expensive bottle of Scotch you have in with your fishing gear, but that doesn't mean you should burn just anything in one. If you burn fuel other than those approved for normal use (Jet A, A-1, B) they fall into the emergency fuel category, you might be able to get home, but start saving for a new engine.

This guy builds Yukons with a 120 hp turboprop option. Fuels ? Diesel, Bio Diesel, Jet A, JP5, JP8 and Heating Kerosene.


http://www.watsongroup.ca

In idea is always good, back when it was an idea. :crazyeyes:

highroads
08-23-2004, 11:27 PM
In my prior life I worked on the certification of the Garrett engines for Ag operations using Diesel fuels. We found little difference in performance, function and turbine life. Turned out that the jet fuels and diesel fuels were almost indistinguishable chemically, the only cancerns were quality controls for diesel were not regulated by law as were the jet fuels.

AlaskaAV
08-24-2004, 08:37 AM
The arctic grade diesel fuel produced by a small refinery owed by ARCO on the north slope of Alaska at Prudhoe Bay was tested by both Boeing and P&W and found to be the same as Jet A-50 with just a little more sulfur. It was certified for use in all of our turbine powered aircraft.
At 50 degrees below zero on the ground, there were no gelling problems when being used for vehicles and generators and needless to say, none in our aircraft either. There was no limit on the amount we could burn but normally for our 737s, we ran round trip fuel and at times, even defueled into our storage tanks when we could.

Crash
08-24-2004, 10:00 AM
I still would question the ability of a turbine engine on a Cub to work as good as a recip in a tight situation where you need to "blip" the power to get over an obstacle. All the turbine engined aircraft I have ever flown in seemed slow to respond and every thing was done smoothly with long approaches and no jockeying around. Crash

AlaskaAV
08-24-2004, 10:43 AM
I still would question the ability of a turbine engine on a Cub to work as good as a recip in a tight situation where you need to "blip" the power to get over an obstacle. All the turbine engined aircraft I have ever flown in seemed slow to respond and every thing was done smoothly with long approaches and no jockeying around. Crash

This is true for jet aircraft. But when you are working with a turbo prop, and I will use our PC-6 Porters as an example, they are flown different.

On approach when there is a sudden need for power for an abort or whatever, you are already at say N1 of 83% and with just a little prop cranked in to keep speed where you want it. Go into ground fine and you have a big airbrake out front. When you need that extra power, there is no spool up time, only the time it takes to change the prop configuration and that starts almost immediately.

Having been around our Porters for several years, recip and turbine, I have to believe the Cubs with a recip and turbine comparison would be the same as our Porters with a recip against a turbine powerplant.
A person has to fly them totally different but there should really be a great gain if performance. Needless to say, a loss of weight but the difference in fuel weight takes most of that away.

Something else to consider about a turbine powered Cub. Fit the aircraft with long legs to keep the prop higher and away from the gravel or other foreign items. A person will be turning the prop at high RPM far longer than with a recip engine.

highroads
08-24-2004, 08:13 PM
A single shaft turbine such as the ATP or Garrett are typically running at or near 100% RPM during landing and take off. Thus no spool up time is required. On the Garrett engine, for a power lever slam, the time from minimum power to full power was under .5sec. or in other words just the time to move the Power lever and slew the prop. The time was dictated by the propeller slew rate as the turbine is already at speed. A PT6 or similar free turbine engine will take a little more time because of the gas generator spool up time. A reciprocating engine with a constant speed prop will also be controlled by the propeller slew rate. The propeller slew rate is going to be insignificant in most cases as the average pilot is going to move the power level (throttle) deliberately with haste but not in a slam fashion even in an emergency situation.

AlaskaAV
08-24-2004, 08:44 PM
A single shaft turbine such as the ATP or Garrett are typically running at or near 100% RPM during landing and take off. Thus no spool up time is required. On the Garrett engine, for a power lever slam, the time from minimum power to full power was under .5sec. or in other words just the time to move the Power lever and slew the prop. The time was dictated by the propeller slew rate as the turbine is already at speed. A PT6 or similar free turbine engine will take a little more time because of the gas generator spool up time. A reciprocating engine with a constant speed prop will also be controlled by the propeller slew rate. The propeller slew rate is going to be insignificant in most cases as the average pilot is going to move the power level (throttle) deliberately with haste but not in a slam fashion even in an emergency situation.

Pretty close to my thoughts although I was not around the Garretts that much even though we ran them in our Skyvans. I was not aware the Garretts could move the prop that fast and our drivers really didn't like them. Not enough power they kept saying. I did miss being able to go into feather when shutting the Garretts down as with the P&Ws since it was so much safer for our passengers. For some reason I remember the PT-6s and props that we ran on our Porters could change the prop positions much faster than what was able to be done on our Twin Otters with a different model of the PT-6 but of course, I could be wrong. Something, maybe knowledge, keeps reminding me that we ordered our P&W powered Porters with a different PT-6 engine model than normally used at the time back in the 60s. As I recall at the time we ordered our Porters, there were something like 4 different models of the PT6 engine available at the time but than again, that was 40 years ago and I sure hate to start an arguement over an engine and prop setup on new special order aircraft we purchased so better back out of this one. But after flying them, I suspect I might have some idea of what we were flying.

highroads
08-24-2004, 10:21 PM
The Skyvans had the Garrett "Century" engines installed which were thermodynamically rated at 715 shaft horsepower. The Skyvan could have used a bigger engine but shorts never went for the larger engine. Later Shorts created the SD360 with the PT6 and dropped the Skyvan. Many Skyvan's remain in service today because that large box with loading ramp could carry oversized cargo and the airplane had a lot of versatility. There was a version of the Porter which had the Garrett engine in it. It was rated at 575 hp and had inflight Beta mode capability. The engine installation was done in Phoenix by Garrett and was produced in production by Fairchild for the CIA for Vietnam operation. It had spectacular performance, able to get into and out of postage stamp sized strips.

geoffmeyer
08-25-2004, 12:39 AM
Stephen - I think you are correct. The cub is on the back-burner at Innodyn and Rivers Aeronautical. Can't blame them. The RV is such a big market. If you want to do this installation yourself, or have someone do it, they will sell the engine and allow you to bypass Rivers Aeronautical. They don't advertise this, but I think they are starting to change their attitude. If you call Innodyn & ask for Charlie, he can tell you more.

This may interest you - all the engines they sell - from 160-255hp are the same weight (188lbs dry). What they are doing is de-rating them, like P&W, GE, CFM...etc. The 255hp engine has a $34,500 price (although they claim the TBO will be the same on all of their engine models, I don't know if I believe that yet. One of the reasons the engines on airliners are purchased de-rated is for improved engine life). The prop, spinner & controls are roughly $6000. You could then spend another $12000 with Rivers, or take it to someone else (which is what I'm doing). The plenum (air flow control) is something else that will probably have to be purchased from Innodyn - they don't have a price on it yet.

It will be hard to beat the power to weight ratio of the 255hp version of this engine, and if it runs as advertised, it should save money in the long run....If you show interest by calling Charlie, I think it will help push their cub project along.

G

AlaskaAV
08-25-2004, 02:48 AM
Interesting Don. I was not aware of the Garrett mod. I knew they were using the Astazou powered Porters in Vietnam. We had a couple and they didn't perform anywhere near our P&Ws and forget the one recip we had, 09Z. It was almost useless for us due to lack of power.

Ahmet Kamil
08-28-2004, 06:00 AM
First, the idea is great. Second, you damn know this game :P Certainly it has to be with CS prop (to eliminate your worries, which are true). My comment; you will have to place the engine almost two times further ahead, and the inertial forces acting on the engine mounts will be too much, compared with the reciprocating engine (too many high rev. parts like turbine, gear train and all that). So be carefull with the engine seperation danger.

FixedWing
08-28-2004, 02:51 PM
you will have to place the engine almost two times further ahead, and the inertial forces acting on the engine mounts will be too much, compared with the reciprocating engine (too many high rev. parts like turbine, gear train and all that). So be carefull with the engine seperation danger.

I wonder if this is true. I would expect vibrations to be less on a turbine engine than a reciprocating engine. So I would expect less fatigue problems and not more. Is engine seperation really a risk? I don't hear of many accidents of that nature.

Also, if the aircraft is being engineered from the beginning for a turbine engine, surely it would be possible to adjust the design to take advantage of the lower engine weight? At the least, I would expect that more components could be moved forward. Though maybe there is a limit to what can be moved forward...

Stephen

AlaskaAV
08-28-2004, 03:23 PM
you will have to place the engine almost two times further ahead, and the inertial forces acting on the engine mounts will be too much, compared with the reciprocating engine (too many high rev. parts like turbine, gear train and all that). So be carefull with the engine seperation danger.

I wonder if this is true. I would expect vibrations to be less on a turbine engine than a reciprocating engine. So I would expect less fatigue problems and not more. Is engine seperation really a risk? I don't hear of many accidents of that nature.

Also, if the aircraft is being engineered from the beginning for a turbine engine, surely it would be possible to adjust the design to take advantage of the lower engine weight? At the least, I would expect that more components could be moved forward. Though maybe there is a limit to what can be moved forward...

Stephen

Stephen
I will stay away from the Super Cub Turbines since I am only learning about them but will pass on what knowledge I have about our Porters but the principals have to be the same.

We had both the recip and two different models of turbines. Needless to say, the recip was mounted close to the fire wall and the turbines really stuck out much the same as a modified Beaver and Otter and other older aircraft modified to take turbine engines, even the DC-3s. We never had any problems with the extended nose and engine mounts, mainly because of the lack of the torque problem, only the strength of the fuselage just forward of the tail wheel was a major problem so we, in a way, had to rebuild that area.

Remember, with a turbine, you have almost no torque to worry about during takeoff and in flight as there is with a recip. Very little vibration as mentioned before and any vibration usually comes from a nicked prop durring take off. Just consider the number of moving parts in a turbine as compared to a recip. As I recall, every one of our Porters carried a file just in case.

An interesting thing about a turbine Porter is that a person can stand in front of the prop and hold it with a hand, maybe two, while the engine is lit up and all that happens is that the prop bends a little if it is in feather as is the usual shutdown procedure with the P&Ws. At somewhere near N1 45%, the person has to let go though. There is no direct gear box from engine to prop, only to the generator/starter, the same unit using reverse current power, and that is on the back side of the PT-6 model we used. The Porters carry a couple of very heavy deep cycle batteries in the nose behind the engine so that helps with W&B. I suspect each battery weighs close to 90 pounds each.

geoffmeyer
08-28-2004, 05:23 PM
Here are the numbers I have for the weights. If they look off, please correct them. They are estimates, as I have not weighed any of these items myself.

188lbs: Engine (power head, gear reduction unit, prop flange, starter, alternator, fuel system, fuel computer)
47lbs: Prop (NSI CAP200):
10lbs: Engine mount
4lbs: Exhaust
50lbs: 2 Batteries
2lbs: Battery cables & fittings
4lbs: Fuel Pumps (2)
12lbs: Cowling
8lbs: Header tank
8lbs?: Plenum

So approximately 333lbs firewall forward. Anyone have numbers on an O-360 (firewall forward weights - apples to apples comparison)?

Geoff

AlaskaAV
08-28-2004, 05:29 PM
Here are the numbers I have for the weights. If they look off, please correct them. They are estimates, as I have not weighed any of these items myself.

188lbs: Engine (power head, gear reduction unit, prop flange, starter, alternator, fuel system, fuel computer)
47lbs: Prop (NSI CAP200):
10lbs: Engine mount
4lbs: Exhaust
50lbs: 2 Batteries
2lbs: Battery cables & fittings
4lbs: Fuel Pumps (2)
12lbs: Cowling
8lbs: Header tank
8lbs?: Plenum

So approximately 333lbs firewall forward. Anyone have numbers on how much an O-360 firewall forward weighs? (Apples to Apples comparison)

Geoff

Geoff
Numbers look good except for maybe the batteries. I know pretty well what the Porters carried but have no idea what the APU engine will need for the Super Cubs.
Although I am not aware of what will go into the Super Cubs, I have an idea of the weight of the APU in say a 737. I have a feeling your weight of the engine is very close to accurate.

Flying Dave
08-28-2004, 10:10 PM
I could have sworn I saw a SC at OSH this year that appeared to have a turbine installed and looked to be in flying condition. I did not get a chance to see it up close so I can not confirm the engine installation. Anybody else see it or was I seeing things??

Dave

highroads
08-28-2004, 11:07 PM
An analogy might be the Maule piston vs the Maule turbine (Allison)

..................................Piston.......... .................Turbine
GW.............................2500............... ..............2500
Emp Wt.......................1665..................... ........1570
T.O. pilot,1/2 fuel.........250...............................200 ft
T.O. ovr 50ft. obst........600...............................600
Fuel flow cruise............11gph........................... .25.9gph
Cruise speed................160mph....................... .190mpH

Some of the weight gain of the turbine is offset by a heavier (3bld) prop. required to handle the extra power. heavier mount system, fire protection, etc. On big turbine engines vs big piston engines the weight improvement is far more significant. With little turbines the percentage of the total powerplant that is turbine is smaller thus weight gain smaller.
More info can be gained from the Maule website
http://www.mauleairinc.com/Our_Planes/index.html

FixedWing
08-28-2004, 11:34 PM
Ernie pretty much confirms my own thinking on this ? that there shouldn?t be any particularly big problem with mounting a turbine engine verses a reciprocating engine and in many way, it might be simpler.

I am wondering if the Innodyn engine is going to need the same level of battery power to crank that engines in aircraft such as the Porter do? Surely the smaller engine would require less? Also, since this is an Experimental catagory aircraft, are there better batteries out there that might be used for this purpose?

The component weights that Geoff and Highroads list pretty much suggest that there isn?t going to be a massive difference in the weight distribution of the aircraft and probably moving a few items forward would make a big difference. Query, if the airframe is being built from scratch, what is to stop someone from actually moving the windshield and firewall slightly forward?

But one thing Highroads points to really makes me think. He lists the gross weight of the Maule as the same for both piston and reciprocating versions. But the Turbine Supercub will be certificated in the Experimental category and the Innodyn engine is available up to 255 hp. This additional power comes with no weight penalty. Query, with so much power available, is there any reason why the builder shouldn?t certify the aircraft to a higher gross weight? And if so, what is possible with a Supercub with so much power? Is it possible that we could end up with a Supercub weighing almost 100 lbs less and with a new higher gross weight?

Stephen

geoffmeyer
08-29-2004, 12:58 AM
I believe gross weight is a function of several things, including wing & strut structure.

FixedWing
08-29-2004, 06:20 AM
I believe gross weight is a function of several things, including wing & strut structure.

So what I'm wondering is, what is the limiting factor on a Supercub? Is it available power? Or is it something else?

Have any Supercubs been certified at higher gross weights?

Stephen

Ahmet Kamil
08-30-2004, 05:23 AM
Can't be certified for higher gross weights I think, because the specific fuel consumption of recip, sweeps away the weight advantage gained by turbine (11GPH versus 26 GPH). Nobody has any objection if you will be happy with 1 hour range :)

puttputt
09-14-2004, 10:32 PM
Ernie, why does a turbine have "almost no torque to worry about"? Yer still twisting a prop that makes gobs of thrust. Don

AlaskaAV
09-14-2004, 10:51 PM
Ernie, why does a turbine have "almost no torque to worry about"? Yer still twisting a prop that makes gobs of thrust. Don

Don, I believe I stated as compared to a recip engine configuration. You do not have all the moving parts to create the torque.
Flying a turbine is so smooth that it can get a person into trouble until the person gets used to it. In a recip, say on departure, you have to always keep ahead of the heading and in a turbine, a person can concentrate more on performance.

I may not be saying this correct but it is unbelievable what the difference is.

Bob Breeden
09-15-2004, 10:46 AM
Has anyone in contact with the Smith father and son team in Ontario heard about the current status of the nearly complete Innodyn powered Smith Cub that was at Oshkosh in Olive Drab paint? Many SuperCub.org members saw that Cub at the Innodyn booth. It sure stood proud on extended gear and tall tires with that long nose!

My recollection was that this was being built for or by Mr. Smith.

Is it flying yet?

What has the flying experience with this aircraft been like?

Thanks,
Bob Breeden

geoffmeyer
09-15-2004, 10:53 AM
I spoke with Innodyn yesterday. The Turbine cub is not flying, or finished. They say it is close & will possibly be flying within a month...lets hope!

mvivion
09-15-2004, 11:11 AM
So, what happened to the turbine Super Cub which was at Sun N Fun in 2003? It was assembled and on floats, but uncovered. When I noted that it appeared the same airplane, in the same condition, was at Sun N Fun in 2004 with no apparent progress, someone noted that this was a different airplane.

So, again, where is the airplane that was at Sun N Fun 2003? Seems like if it was this close to completion then, and experimental, it should at least be about ready to fly.

It appears that there are at least two Cubs with these little turbines on them somewhere. Just curious where.

Note that there is an RV currently FLYING with one of these engines on it. Considering that the RV is a much shorter aircraft, it appears that they figured out the W & B issues adequately on it. Doesn't seem like the Cub would be that much more difficult.

Fuel burn will be a big issue.

Ernie, turboprops still make massive amounts of torque and p-factor, related to the prop, not the engine, though there may be some difference in engine torque.

Note that the military, when they designed their new turbo prop trainer, made by Raytheon, (I believe) specified that the airplane had to have an on ground yaw damper to counteract the effects of p-factor and torque TO BETTER SIMULATE PURE JET powered aircraft.

You are correct in that turbojet powered aircraft exhibit no left turning tendency on the ground, but turboprops sure do.

MTV

geoffmeyer
09-15-2004, 12:00 PM
The Innodyn engine is advertised to burn roughly 7gph per 100hp below 10,000' (this figure improves at higher altitudes). That makes sense, especially when you compare with other turbo-props. The Allison 250-B17C engine burns about 20gph at a cruise power setting of 310hp (6.45gph per 100hp). The Walter M601D burns 65gph at 657hp (9.9gph per 100hp). The innodyn falls somewhere inbetween these two. So power back the 255hp Innodyn to 150hp in cruise. You should burn roughly 10.5gph. I don't know much about the pistons - how does that compare to an O-360?

Geoff

Bob Breeden
09-15-2004, 12:02 PM
Thanks, Geoff.

Hi, Mike.

I sure am comfortable flying behind a trusty Lycoming when crossing the Inlet exploring western Alaska, but nonetheless, there may well be a time and place for a Turboprop Cub.

Especially in the drama/performance department. I have thought alot about the turboprop aerobatic aircraft that flamed out while doing square loops at a constant airspeed, and couldn't be safely deadsticked from low altitude because of the drag of the windmilling prop, the prone-to-stall wing, and the light weight of the aircraft. That pilot suffered permanent backbone compression related injuries.

Safe drama/performance for the Super Cub would include what others have thought of, which is even more stellar takeoff performance. And, as others have mentioned, safe drama in the landing phase will also require some quick, smooth, reliable, controllable and intuitive use of beta.

There is nothing like the millions of hours in nearly every wise (and otherwise human) use of the certified piston powered cubs to establish a refinement in safety we now utilize daily.

It will be interesting to see how smoothly, and utimately successful, the accomodation of and transition to Turbines can be. I certainly applaud those who think this endeavor through and do so successfully.

Bob Breeden

Tom Jones
09-15-2004, 01:26 PM
Bob,

The Salinas Airshow turboprop crash you refered to, at least according to the NTSB, was pilot error. The Pratt & Whitney said the teardown showed the engine developing middle to high power at impact. I've talked to Wayne a couple of times since the accident and he would beg to differ!

He was landing out of a loop (a vertical eight I believe), descending at 50 to 60 degrees nose down, something that required very precise airspeed and drag control, and he said it didn't power up immediately when he brought the prop out of beta, so he couldn't get up the speed necessary to round out at the bottom to land.

It's probably related to spool-up time. It doesn't take long to go 800' down at that kind of deck angle, and it's probably not the kind of flying anyone would consider in a Super Cub, turboprop or not!

The factual report is here: http://www.ntsb.gov/ntsb/GenPDF.asp?id=LAX00LA003&rpt=fa

The probable cause report is here: http://www.ntsb.gov/ntsb/GenPDF.asp?id=LAX00LA003&rpt=fi

Tom

Bob Breeden
09-15-2004, 04:38 PM
Tom,

Thanks for the links. Having now read both, I can see that, from the NTSB perspective, this was pilot error. And you are right, descending 800 feet at a 50 or 60 degree angle at 80-90 knots only takes about 9 seconds, (figuring the vertical component to be 60 mph). I figure that changing from Beta to forward thrust would have been in the last 200 vertical feet, which only gives 2 seconds to obtain forward thrust and flare.

If it is pilot error, as the NTSB asserts, check out that Wayne Handley had 25,000 hours, and 200 plus in this airplane, and that didn't save his landing. Yes, as an aside, he had the pressure of the crowd, and the extra enthusiasm that comes from that (not good) but he was used to that.

It is imperitive, to my way of thinking, to read about this accident and look at how that could be waiting to trap a turboprop Super Cub.

First, we land our Cubs as short as we can, over obstacles. Idle thrust, full slips at full flaps, at stall plus one knot, with a touch of power to round out at the bottom. A short dive at the bottom to get the necessary airspeed to flare is safer, but still we use power to flare sometimes. Or even drag it in, working way out on the backside, hanging on the prop. This is routine stuff to muster the best performance out of our Cubs. It is not a stretch to suggest that we would not learn to use beta, to descend even steeper, and if our timing is not spot on, incur a similar event as described in this accident report. The report states that the turbine and prop were pulling hard at the time of impact. That power was just called for a second too late, which could have been affected by gusts or other variables as well.

The Super Cub is such a fine machine to learn to fly well, and safely, in the full range of its performance. I hope that the turboprop can be incorporated, with all it additional capabilities, just as safely. A Cubs inherent stability, high lift wing, powerful tail and slow flying capabilities which give us long times to react will make this kind of accident less likely than on the aerobatic plane. But such a Cub, flown in this manner, will become dependent on the engine and prop both operating, and being operated perfectly, every time. So much for landings.

Takeoffs with 255 hp at 35 mph will have a deck angle of over 60 degrees as well - and may even be vertical in gusts. The time required for pitchdown in the event of engine failure, or to break a stall, will be even longer that that of a light cub climbing at 35 mph under an 8241 prop. Fuel systems will have to be be designed to carry fuel the 3 vertical feet up to the engine.

Ernie, how did the Porter get fuel to the engine, and how much time did your crack pilots take to master flying it the way you have described in your writings? Were there accidents with the Porter related to max performance takeoffs and landings?

Bob Breeden

AlaskaAV
09-15-2004, 05:43 PM
Bob
I am not sure how the fuel system was designed on our Porters so cannot offer anything there. Since all of my time in our company Porters was just for fun over a two year period, I never got into systems of the aircraft.

The only company pilot that I ever flew with in a Porter and the guy that taught me how to make that ugly thing work flew it like he was born in it. He was also a CFI at the time. He was a long time bush pilot for us but from the time we got the Porters until he was assigned to my operations, I suspect it was like two years. Keep in mind though, on our bush route system, the legs were very short and a pilot would go through many cycles per day. Some legs were as short at 2.5 miles and some about 10 miles. A person gets to do a lot of playing that way. I suspect in our operations at the time, a bush pilot would have more than 10 times the cycles of a normal light aircraft pilot in a "normal" scheduled airline operation. Also, they knew the eyes were not watching them.

From the descriptions above, I suspect he found his own way to get in and out of short strips that were not covered in the book. That was the way he taught me how to work the machine. When I first started working with him, he kept impressing on me to keep it spooled up when landing and use the prop. So called instant power he would say. Same on take off. Taxi out, line up and when ready, spool it up in ground fine and once N1 was near 92%, lay the prop to it. This had to be done real fast or you would overheat the engine within just a few seconds until you got the prop in for cooling. When you get full hp, whether 650 or 550 shp, within a second or two, it really lays you back and you are off the ground in just a few more seconds. I know this is not what the book says about proper procedures but in those days, most of our pilots could not even know how to read so they threw the book away. :wink: He used these procedures as practice so when he came up with a 2000 foot runway with a soft spot right in the middle, he would be ready for it.

To my knowledge we never had a problem with high performance operations but did have some rather odd situations.

http://www.supercub.org/gallery/view_album.php?set_albumName=album87

The Porter on the logs happened durring landing and the one on skis happened inflight in severe turbulence.

When doing a three point landing, the pilot had to be very careful not to land tail wheel first or it would buckle the fuselage just forward of the tail wheel. There was no tubing in the fuselage of the Porters.

Our Twin Otter and Skyvan pilots almost always flew them by the book though.

I hope I live long enough to see one of those turbines in a Super Cub. With the right pilot, it will be a fantastic fun machine.

AlaskaAV
09-15-2004, 06:03 PM
So, what happened to the turbine Super Cub which was at Sun N Fun in 2003? It was assembled and on floats, but uncovered. When I noted that it appeared the same airplane, in the same condition, was at Sun N Fun in 2004 with no apparent progress, someone noted that this was a different airplane.

So, again, where is the airplane that was at Sun N Fun 2003? Seems like if it was this close to completion then, and experimental, it should at least be about ready to fly.

It appears that there are at least two Cubs with these little turbines on them somewhere. Just curious where.

Note that there is an RV currently FLYING with one of these engines on it. Considering that the RV is a much shorter aircraft, it appears that they figured out the W & B issues adequately on it. Doesn't seem like the Cub would be that much more difficult.

Fuel burn will be a big issue.

Ernie, turboprops still make massive amounts of torque and p-factor, related to the prop, not the engine, though there may be some difference in engine torque.

Note that the military, when they designed their new turbo prop trainer, made by Raytheon, (I believe) specified that the airplane had to have an on ground yaw damper to counteract the effects of p-factor and torque TO BETTER SIMULATE PURE JET powered aircraft.

You are correct in that turbojet powered aircraft exhibit no left turning tendency on the ground, but turboprops sure do.

MTV

MTV
It was my intent to share the differences in our recip and turbine Porters, same airframe under same conditions, on the subject, not to compare apples and oranges. What the prop does or does not do on a Porter is almost the same even though the props are different between the recips and turbines although no bata on recips of course. I was under the impression that someone was interested in what the differences might be.
Sorry MTV.

CptKelly
09-15-2004, 06:22 PM
Don't some recips have beta range props? Seems to me I heard that the C124 had beta? Might have been another plane, but thats what comes to mind.
Why shouldn't recips have beta anyway?

Mike

AlaskaAV
09-15-2004, 06:43 PM
Don't some recips have beta range props? Seems to me I heard that the C124 had beta? Might have been another plane, but thats what comes to mind.
Why shouldn't recips have beta anyway?

Mike

Recips have bata of course but just not our recip Porter 09Z. For us, what a useless aircraft. I was just trying to explain the difference between the two different Porters in the Wien fleet. Photo of that aircraft is available on airliners.net.

geoffmeyer
09-15-2004, 08:49 PM
Tom,

Thanks for the links. Having now read both, I can see that, from the NTSB perspective, this was pilot error. And you are right, descending 800 feet at a 50 or 60 degree angle at 80-90 knots only takes about 9 seconds, (figuring the vertical component to be 60 mph). I figure that changing from Beta to forward thrust would have been in the last 200 vertical feet, which only gives 2 seconds to obtain forward thrust and flare.

If it is pilot error, as the NTSB asserts, check out that Wayne Handley had 25,000 hours, and 200 plus in this airplane, and that didn't save his landing. Yes, as an aside, he had the pressure of the crowd, and the extra enthusiasm that comes from that (not good) but he was used to that.

It is imperitive, to my way of thinking, to read about this accident and look at how that could be waiting to trap a turboprop Super Cub.

First, we land our Cubs as short as we can, over obstacles. Idle thrust, full slips at full flaps, at stall plus one knot, with a touch of power to round out at the bottom. A short dive at the bottom to get the necessary airspeed to flare is safer, but still we use power to flare sometimes. Or even drag it in, working way out on the backside, hanging on the prop. This is routine stuff to muster the best performance out of our Cubs. It is not a stretch to suggest that we would not learn to use beta, to descend even steeper, and if our timing is not spot on, incur a similar event as described in this accident report. The report states that the turbine and prop were pulling hard at the time of impact. That power was just called for a second too late, which could have been affected by gusts or other variables as well.

The Super Cub is such a fine machine to learn to fly well, and safely, in the full range of its performance. I hope that the turboprop can be incorporated, with all it additional capabilities, just as safely. A Cubs inherent stability, high lift wing, powerful tail and slow flying capabilities which give us long times to react will make this kind of accident less likely than on the aerobatic plane. But such a Cub, flown in this manner, will become dependent on the engine and prop both operating, and being operated perfectly, every time. So much for landings.

Takeoffs with 255 hp at 35 mph will have a deck angle of over 60 degrees as well - and may even be vertical in gusts. The time required for pitchdown in the event of engine failure, or to break a stall, will be even longer that that of a light cub climbing at 35 mph under an 8241 prop. Fuel systems will have to be be designed to carry fuel the 3 vertical feet up to the engine.

Ernie, how did the Porter get fuel to the engine, and how much time did your crack pilots take to master flying it the way you have described in your writings? Were there accidents with the Porter related to max performance takeoffs and landings?

Bob Breeden

Bob - great stuff to read & think about. I had not considered what a prolonged high deck angle would do to fuel flow. I really appreciate the thoughts.

Here is something else to consider...since the direct drive engines (like the Innodyn & unlike a PT6) run at high rpm during landing & rollout, the prop, when in BETA, blocks more air than usual. This could cause a loss of rudder authority under certain conditions...I would imagine by the time one is slow enough that the prop blanks out the rudder, you could be using differential braking. I think you hit the spot on your last post - with a turbo-prop, there are more tools for the pilot to use to his advantage, and as a result, there are more ways to get in trouble.

Geoff

AlaskaAV
09-15-2004, 09:25 PM
Great thoughts Geoff and I learn something new every day.

I have been trying to share my thoughts about the PT-6 in our Porters many years ago. I have no real knowledge about the APU turbines going into the Super Cub so I am just learning. I know what I could do with our Porters but I try very hard not to argue with anyone who are far more experienced about what our aircraft could do many years ago.

The way I was taught to fly the Porter would never work with the direct dive engines you wrote about. I was not even aware that the APU engine was direct drive but have always said it was something new to me.
That, to me, would take all the fun out of flying a single engine high perform turbine aircraft.
No wonder there is a difference in ideas.
Thanks for setting me straight.

Bob Breeden
09-16-2004, 04:26 PM
I don't want to be a naysayer about the Turbine Super Cub. Simply thinking through the implications, should the opportunity arise to fly one.

I have talked to Jon who flys the Innodyn RV. He is quite a pilot, and we have a shared enthusiasm for Cubs. He is the guy that owned the SuperCub with magic marker notes and signatures that captured so much attention years ago at Oshkosh. Also, the back of his hangar has a big stack of bowling balls. I leave it to your imagination to figure out what they are for...

The RV is not flown much between airshows, and Jon says that in his RV/Innodyn demonstrations at Oshkosh that he is required not to use reverse thrust. But he says it will really shine; really impressive flying of the type Ernie talks about with the Porters.

We have gone from 65 horse J-3's to 90, 135, 150 (mine is), 160, 180 and now are about to see 255 horse Super Cubs.

The Radio Control guys at my friends local strip have got a new thing going. A couple of years ago, one, and only one of these guys put enough power on an Extra model such that thrust exceeded weight. He learned to slow fly up to a point 20 feet in front of himself, and rotate the nose up to vertical and hold it with power. It will torque roll slowly, but is absolutely stable as he controls with elevator and rudder alone. To resume flight, he powered up and left verically, pitching over as flying speed was achieved, which he could tell by the ailerons being powerful enough to counter the torque roll.

Like the extra power we have become accostomed to in Super Cubs, now 5 or 6 guys are flying like this at my friends strip with the incredible new planes they have built.

I suppose it is only a matter of time until this is the latest rage in Super Cub flying....

Bob Breeden

geoffmeyer
09-16-2004, 05:33 PM
I don't want to be a naysayer about the Turbine Super Cub. Simply thinking through the implications, should the opportunity arise to fly one.

I have talked to Jon who flys the Innodyn RV. He is quite a pilot, and we have a shared enthusiasm for Cubs. He is the guy that owned the SuperCub with magic marker notes and signatures that captured so much attention years ago at Oshkosh. Also, the back of his hangar has a big stack of bowling balls. I leave it to your imagination to figure out what they are for...

The RV is not flown much between airshows, and Jon says that in his RV/Innodyn demonstrations at Oshkosh that he is required not to use reverse thrust. But he says it will really shine; really impressive flying of the type Ernie talks about with the Porters.

We have gone from 65 horse J-3's to 90, 135, 150 (mine is), 160, 180 and now are about to see 255 horse Super Cubs.

The Radio Control guys at my friends local strip have got a new thing going. A couple of years ago, one, and only one of these guys put enough power on an Extra model such that thrust exceeded weight. He learned to slow fly up to a point 20 feet in front of himself, and rotate the nose up to vertical and hold it with power. It will torque roll slowly, but is absolutely stable as he controls with elevator and rudder alone. To resume flight, he powered up and left verically, pitching over as flying speed was achieved, which he could tell by the ailerons being powerful enough to counter the torque roll.

Like the extra power we have become accostomed to in Super Cubs, now 5 or 6 guys are flying like this at my friends strip with the incredible new planes they have built.

I suppose it is only a matter of time until this is the latest rage in Super Cub flying....

Bob Breeden

Bob - What does your friend (Jon) think of the Turbine Super Cub conversion? Why is it that he is not supposed to use reverse thrust? I get conflicting information about this engine, but I always seem to come back to the prop. I am a bit blinded by my enthusiasm for this project, so its always good to read what the naysayers say!

Geoff

AlaskaAV
09-16-2004, 06:11 PM
I don't want to be a naysayer about the Turbine Super Cub. Simply thinking through the implications, should the opportunity arise to fly one.

I have talked to Jon who flys the Innodyn RV. He is quite a pilot, and we have a shared enthusiasm for Cubs. He is the guy that owned the SuperCub with magic marker notes and signatures that captured so much attention years ago at Oshkosh. Also, the back of his hangar has a big stack of bowling balls. I leave it to your imagination to figure out what they are for...

The RV is not flown much between airshows, and Jon says that in his RV/Innodyn demonstrations at Oshkosh that he is required not to use reverse thrust. But he says it will really shine; really impressive flying of the type Ernie talks about with the Porters.

We have gone from 65 horse J-3's to 90, 135, 150 (mine is), 160, 180 and now are about to see 255 horse Super Cubs.

The Radio Control guys at my friends local strip have got a new thing going. A couple of years ago, one, and only one of these guys put enough power on an Extra model such that thrust exceeded weight. He learned to slow fly up to a point 20 feet in front of himself, and rotate the nose up to vertical and hold it with power. It will torque roll slowly, but is absolutely stable as he controls with elevator and rudder alone. To resume flight, he powered up and left verically, pitching over as flying speed was achieved, which he could tell by the ailerons being powerful enough to counter the torque roll.

Like the extra power we have become accostomed to in Super Cubs, now 5 or 6 guys are flying like this at my friends strip with the incredible new planes they have built.

I suppose it is only a matter of time until this is the latest rage in Super Cub flying....

Bob Breeden

Bob
The guy that was working with me on our PT-6 Porter showed me how to do that same maneuver as the RC 300 you told about. For some reason, it sticks in my mind that he used some flap but don't quite understand why. He told me the aircraft was actually mushing horizontal at about 5 knots but it was holding altitude as he wanted. There was no indication of airspeed though since there was no forward speed. We were empty on a return cargo flight and light on fuel. He went into it just as you described and kept adding power until altitude was steady. As I recall from the gauges, he had plenty of power left but this was some 40 years ago at Dahl Creek and minds can play tricks at times.
I tried it many times but could do nothing compared to what he could do.

AlaskaAV
09-16-2004, 06:34 PM
Geoff
Since I am just learning about the turbine powered Super Cubs this gets very interesting to me.
Reference the use of full reverse props: Is it posable those that are working on the designs might be concerned with the light weight of the tail on a Super Cub?
An example.
In the Katmai area of Alaska, we were using a PT-6 powered Porter on amphib floats to move our fishing guests around out of King Salmon. At one point at a remote camp, the pilot had brought it up near the shore and turned it around. He lifted the water rudders and went into bata to back the floats up on shore. Problem was he added a little too much power and bingo, nose and engine right in the water with the tail sticking straight up. Ruined engine and probably the prop also. Since he was the son of the airline owner, not much was said about it though.

When you stop and think about it, maybe the Super Cub might even have a more critical problem such as this. I suppose under certain conditions and power settings, a person could actually flip a Cub upside down while going into bata.

Just a thought.

geoffmeyer
09-16-2004, 07:11 PM
Geoff
Since I am just learning about the turbine powered Super Cubs this gets very interesting to me.
Reference the use of full reverse props: Is it posable those that are working on the designs might be concerned with the light weight of the tail on a Super Cub?
An example.
In the Katmai area of Alaska, we were using a PT-6 powered Porter on amphib floats to move our fishing guests around out of King Salmon. At one point at a remote camp, the pilot had brought it up near the shore and turned it around. He lifted the water rudders and went into bata to back the floats up on shore. Problem was he added a little too much power and bingo, nose and engine right in the water with the tail sticking straight up. Ruined engine and probably the prop also. Since he was the son of the airline owner, not much was said about it though.

When you stop and think about it, maybe the Super Cub might even have a more critical problem such as this. I suppose under certain conditions and power settings, a person could actually flip a Cub upside down while going into bata.

Just a thought.

Ernie - That's a good thought. I've heard crop duster pilots say that the tail should be on the ground before going into beta. I would think if the tail is below the nose, then one could go into reverse - light or heavy.

This is why I think the tail should be down before going into reverse (engineers out there - be easy on me!)...If you draw the net force vector experienced during a tail high reverse, you would draw an arrow going from the center of the prop, backwards toward the tail along the thrust line (the arrow represents a rearward force). If you break that arrow into its horizonal & vertical components, you'll see that the horizontal component is the larger of the two, and points toward the tire (in relation to the aircraft's center line, it points downward, and thus pulling the nose down). A tail low aircraft in reverse has the same net force vector pointing from the nose to the tail along the thrust line, but the difference is that the horizontal component (again, the larger of the two components) is now pointing above the thrust line & giving an upward pull on the nose.

So if the tail is down, the way I understand it, the reverse thrust should force it down further, allowing you to really stand on the brakes.

In the real world, did it work that way for you in the Porter?

Geoff

AlaskaAV
09-16-2004, 07:51 PM
Geoff
The guy working with me did not really let me get into high performance flying but always took time to show me how it was done. To my knowledge, I never saw him go into bata on a wheel landing. Remember, the Porter empty has a very light tail but with ten passengers, it was a little different though but this guy never played around when carrying passengers other than the Governor of Alaska on a couple of flights but that was by request from the Governor.

When we dumped that one near Katmai on floats, consider that the aircraft was more or less in level flight attitude and the tail already half way up so it took less energy to make it go over the top. Actually, once above the centerline, the energy required to lift the tail was reduced the higher the tail was.

I like the way you explained the engineering. Makes sense to me so we will both get shot down by the pros but consider this: when landing or any operation in the air, air movement over the tail gives the control. When going into bata, all of that prop wash control is lost and moves to the front of the aircraft where there is no lateral or vertical control at all. In an emergency, tail surface control is needed immediately and granted it is only seconds to change the prop from bata back to alpha but will it be in time?

Let me try to explain something I was taught by my company pilot but never tried.

Inbound on a short final at Dahl Creek over 50 foot trees (imagery) 100 foot from the end of the runway.
Remember guys, this guy taught me to always keep that PT-6 spooled up at all times when doing short field work. Let the prop do the work.
My pilot brought it in (empty and light fuel) just above stall and full flaps. Just at the end of the trees, he would drop the nose into a steep approach, go into ground fine or bata if needed and just over the fence, pull it up and into ground fine and than right into bata again just after a three point. He could stop that aircraft maybe 200 foot from the end of the runway. As I have said many times before, this guy must have been born in a Porter. It was always such a pleasure to fly with this guy and I sure made good use of our empty flights to learn from a master and he always did his best to explain things to me and let me try it at altitude. Did we take it up just to play once in a while? No comment.

geoffmeyer
09-16-2004, 09:42 PM
Ernie - the more I think about my last post, the more I think something is wrong with my logic...but we still know that it is a bad idea to go into reverse before putting the tail down. Maybe another explanation is that the reverse thrust blocks the tail, causing it to loose its aerodynamic down force, and allowing the weight of the nose to take over. If the tail is already down, the aerodynamic downforce is no longer needed because of the weight shift, so reverse does no harm...still just guessing.

Geoff

AlaskaAV
09-16-2004, 10:08 PM
Ernie - the more I think about my last post, the more I think something is wrong with my logic...but we still know that it is a bad idea to go into reverse before putting the tail down. Maybe another explanation is that the reverse thrust blocks the tail, causing it to loose its aerodynamic down force, and allowing the weight of the nose to take over. If the tail is already down, the aerodynamic downforce is no longer needed because of the weight shift, so reverse does no harm...still just guessing.

Geoff

I totally agree with you. I was taught that at any time when landing a Porter, always make sure you were in three point before going into bata. Like our pilot told me, it takes many, many years and cycles to get it down right. I suspect it just came natural to him though.

Consider this concept. When making a wheel landing in a Cub and you really locked up the brakes, what would happen? Now consider the bata as the brakes and the same thing would happen, right?

As I have said before, I have almost no knowledge about the turbine engine to be used in the Cubs and have a hard time understanding why so many comments about slow spool up. I wonder why that turbine in a Cub would be so much different than the PT-6 in our Porters where we didn't have that problem or at least I didn't from the way I was taught to fly it. As an added comment, the PT-6s used in twin engine aircraft do not have this problem.

mvivion
09-16-2004, 11:26 PM
Ernie,

There are a lot of models of PT-6, which is the answer to your last question, basically. P & W has made a lot of improvements to the breed since they first started manufacture. Spool up time is one of those.

MTV

AlaskaAV
09-17-2004, 12:34 AM
Ernie,

There are a lot of models of PT-6, which is the answer to your last question, basically. P & W has made a lot of improvements to the breed since they first started manufacture. Spool up time is one of those.

MTV

I guess what I am trying to say is that when doing high a performance landing or departure in a Porter and I would suspect the same could hold true with a turbine powered Super Cub, I was taught to keep it spooled up and use the prop much like an airbrake or for instant power. Keep in mind, I was trained by one fantastic Porter pilot. Our Twin Otters had the PT-6s also but they were flown much different than the Porters were into real short and possibly soft bush strips.
To me, this would be an operation not covered by the "book" in my day and needless to say, things have changed.
I am just trying to learn about the turbine Cubs. To me, what a bush aircraft if it could be flown like the Porters could be. I really appreciate you guys putting up with my questions.

Bob Breeden
09-17-2004, 02:48 AM
Geoff,

Jon thinks the Turbine Super Cub will be, in a word, GREAT.

Oshkosh, to some degree for all demonstration pilots (and airshow pilots too), keeps a lid on the type of flying done in the demonstration flybys - which are multiple aircraft of differing capablities flying in loose trail formation. After they takeoff, it is basically like several aircraft doing pattern work for 4 or 5 patterns, when one lands and another takes off and joins the group.

It would disrupt things a bit to have Jon climb to 10,000 feet, go to beta and descend vertically at VNE minus 10 knots, then transition to level flight, flare and land, all in one vertical effort. But it has been done.

On takeoff, the plane does accelerate briskly, but this is not optimized with the short prop and high stall speed wing. Perhaps to an RV pilot this would seem like a stellar takeoff. But there at Oshkosh, it appears more that what Jon demonstrates is how quickly it will accelerate up to say 150 knots in climb.

That engine with a long prop, and installed in a Super Cub, the power will be more impressive to Cub pilots for sure.

Bob Breeden

Bob Breeden
09-17-2004, 03:03 AM
Guys,

I don't want to speak for Jon any further. I will look him up and see if he will be willing to join in himself on the SuperCub.org site. He is a great pilot.

Bob Breeden

arcticflyr
09-17-2004, 02:47 PM
Hello this is my first post, I have been looking at the Inodyne for a cub project of mine. The guys at Inodyne are great to talk with. I have a few comments, well more of my opinion. I've operated both free spool and solid shaft turbines commercially they are both great designs. The Inodyne turbine is a solid shaft so there will be no spool up time to worry about. Using the prop control for speed get the same end result as the systems in Alison and Garret turbines with a lot less parts. The Alison runs a 100% the throttle just ads fuel and the prop governs the engine, there is a lot more going on in there but I don't want to make this a ground school. The Inodyne has FADAC on it's fuel control so you change pitch and the fuel control keeps the turbine speed steady. I think it will work great on a cub, instant power. As for reversing on the ground, the only tailwheel turbine I've flown is a beaver, and in it you can go to full rev as soon as the mains are on. Or if you're really friendly with it just before they touch, the spool up time for reverse and the time it takes the prop to change pitch your on the ground before the power comes up. Also I was told the prop on the Inodyne is electric control and can change pitch up to 10 to 12 degree's per second, pretty fast. Well that my two cents worth, I like the site. Jason

behindpropellers
09-17-2004, 03:17 PM
Jason-

What is a typical change (in degrees) of pitch? IE from full fwd to reverse.

Thanks
Tim

AlaskaAV
09-17-2004, 03:57 PM
Hello this is my first post, I have been looking at the Inodyne for a cub project of mine. The guys at Inodyne are great to talk with. I have a few comments, well more of my opinion. I've operated both free spool and solid shaft turbines commercially they are both great designs. The Inodyne turbine is a solid shaft so there will be no spool up time to worry about. Using the prop control for speed get the same end result as the systems in Alison and Garret turbines with a lot less parts. The Alison runs a 100% the throttle just ads fuel and the prop governs the engine, there is a lot more going on in there but I don't want to make this a ground school. The Inodyne has FADAC on it's fuel control so you change pitch and the fuel control keeps the turbine speed steady. I think it will work great on a cub, instant power. As for reversing on the ground, the only tailwheel turbine I've flown is a beaver, and in it you can go to full rev as soon as the mains are on. Or if you're really friendly with it just before they touch, the spool up time for reverse and the time it takes the prop to change pitch your on the ground before the power comes up. Also I was told the prop on the Inodyne is electric control and can change pitch up to 10 to 12 degree's per second, pretty fast. Well that my two cents worth, I like the site. Jason

Jason
Many thinks for stopping by. That is the information I was looking for and answered almost all of my questions. Based on that info, to me it would seem the Inodyne would make the Super Cub fly like a small Porter and the way I was taught it fly it at max performance. Oh how I envy the guys that will get to fly one some day.

I understand the turbine Beaver and the Porters flew about the same but was never in one.

Stick around and let us know how your project is going.

Bob Breeden
09-17-2004, 04:49 PM
Jason,

Yes, I will back up Ernie to say welcome! Let us know about the status of your Cub project, and how you intend to incorporate the Innodyn, and with your turbine experience what your expectations are.

We are all curious, and speaking for myself, I don't have the turbine time. Sounds like it could be used conventionally; my posts on page 3 are related more to if it was used at the ends of the spectum for max performance.

Bob Breeden

AlaskaAV
09-17-2004, 06:16 PM
For those that are interesting in this engine, here is a little more information. I am sure the pros already know this but there are always guys like myself still learning. I keep focusing on the spool up time you guys keep talking about. It seems that this engine is much like the PT-6 I flew 40 years ago and if so, the Cub would fly like a mini Porter and what a dream it will be.

http://www.innodyn.com/aviation/innodyn_turbines.html

geoffmeyer
09-17-2004, 09:38 PM
Jason-

What is a typical change (in degrees) of pitch? IE from full fwd to reverse.

Thanks
Tim

Tim - I was wondering the same thing. The proposed prop is the NSI CAP200. It is very hard to get in touch with anyone at NSI, but I was once able to speak to Lance - I believe he is the owner. He told me the prop would change from full reverse to full coarse in 9 seconds. That is how fast the Innodyn will react since the engine is constantly spooled up. My question, like yours, is how much prop blade angle is needed to go from, say, an idle thrust position to a go-around thrust position, or from an idle thrust position to a max reverse position. Knowing it takes 9 seconds to cycle through it's entire range is helpful information, but I still don't know what that entire range is (haven't been able to get in touch with anyone at NSI for a few months).

Innodyn also tested the MT prop. It worked, but changed pitch slower than the NSI, and as a result, made the engine less responsive. So the prop they want to use is the NSI. NSI's largest diameter prop is 74". A 79" prop is in the works. For our STOL aircraft, I think the larger diameter the better, especially considering the fact that the Innodyn comes in different prop reductions (2750rpm, 2500rpm, 2250rpm). Imagine...the 2500 rpm engine could efficiently turn a 90" prop, or the 2250rpm engine could turn a 100" prop. Like a Helio Courier...

I am really hoping they find a longer prop that will work with their engine. What are some thoughts on longer props? I've always heard that the longer, the better - assuming you still have good ground clearance, and an engine that won't turn so fast that the tips break the speed of sound - is this true about longer props? Should I be holding out for Innodyn to find a long prop?

Geoff

AlaskaAV
09-17-2004, 10:07 PM
Geoff
Are you sure it takes 9 seconds from full bata to full alpha? That is a long time. To me, that sounds more like a spool up situation and would defeat the purpose of high performance operations.

geoffmeyer
09-17-2004, 11:53 PM
Geoff
Are you sure it takes 9 seconds from full bata to full alpha? That is a long time. To me, that sounds more like a spool up situation and would defeat the purpose of high performance operations.

Ernie - No, I am not sure. This is what I remember Lance at NSI saying. It sounds a bit slow to me as well - but going from full reverse to full coarse is a lot of pitch change. Just to be an optimist & guess at some numbers, maybe the pitch change from idle to go-around is 30% of the full range (assuming the prop pitch is able to go well beyond a useable range for the Innodyn - to a coarse condition that is near feather). If that were the case, then full go-around power would take less than 3 seconds, and regular power changes would be fractions of a second. If I remember correctly, that is kind of what Lance @ NSI was explaining to me. If I ever get in touch with NSI, I'll certainly ask more pointed questions.

I can remember this for sure...the Garrett TPE331 was a direct drive engine with a much heavier prop than the NSI. The response was as good as any piston I've flown.

Geoff

AlaskaAV
09-18-2004, 12:26 AM
Geoff
Are you sure it takes 9 seconds from full bata to full alpha? That is a long time. To me, that sounds more like a spool up situation and would defeat the purpose of high performance operations.

Ernie - No, I am not sure. This is what I remember Lance at NSI saying. It sounds a bit slow to me as well - but going from full reverse to full coarse is a lot of pitch change. Just to be an optimist & guess at some numbers, maybe the pitch change from idle to go-around is 30% of the full range (assuming the prop pitch is able to go well beyond a useable range for the Innodyn - to a coarse condition that is near feather). If that were the case, then full go-around power would take less than 3 seconds, and regular power changes would be fractions of a second. If I remember correctly, that is kind of what Lance @ NSI was explaining to me. If I ever get in touch with NSI, I'll certainly ask more pointed questions.

I can remember this for sure...the Garrett TPE331 was a direct drive engine with a much heavier prop than the NSI. The response was as good as any piston I've flown.

Geoff

I spoke with Charlie at Innodyn a little tonight about the engine and will see if I can't get more info next week on the props he is working with. I am trying to think back to the time required to change pitch on the Porters and maybe others that are familiar with the turbine Beavers might have an idea what it takes there. I suspect the Twin Otters and King Airs might be different but have no knowledge about them. As I recall and it has been a long time, it was almost like instant change of pitch on the Porters. I know when landing at ground fine, if you laid the prop to it, it laid you back in the seat immediately not like 4 seconds. Just an observation of course and I could be wrong as I usually am. Something to consider, if in ground fine and going to either bata or forward, you don't go through feather at least on the Porter. I really suspect that will be the type prop chosen for the Innodyne in the Cubs if and when they get it certified.

Our Skyvans had the Garretts but our guys didn't really like them all that well but I have no real knowledge about them. It seems maintenance time was higher on the Garretts in our company as compared to the
PT-6s.

aeronca 1
09-18-2004, 04:00 AM
hey mars man - take it from an a&p, stick with a recip. unless your an overpaid airline pilot with an affection for all things high tech,your waisting your money.rebuild cost is pretty spendy,not to mention field repairs$$$$.if you do go with a turbin,let me know if you need a mechanic because you obviously have moore money than you know what to do with.
good luck :roll: :2gunfire: FWB 603

arcticflyr
09-18-2004, 07:09 AM
Jason-

What is a typical change (in degrees) of pitch? IE from full fwd to reverse.

Thanks
Tim
I'm not sure how fast a hydraulic prop changes pitch, the PT-6 has some lag going into rev, mostly from spool up. N1 is around 72 to 76% percent at touch down, you can overcome this by landing in high idle that puts N1 at 86% they want to float a bit that way but nothing you can't overcome. I think those are the speeds, if not there close.
I think a turbine cub would be amazing, the cost isn't more that a recip, cheaper to run and maintain than a 1930's engine design plus the cost of 100LL keeps creeping up. It would really shine when working high strips where the O-320 feels like it has one mag off, carb heat on and 3/4 throttle.

FixedWing
09-18-2004, 11:36 AM
hey mars man - take it from an a&p, stick with a recip. unless your an overpaid airline pilot with an affection for all things high tech,your waisting your money.rebuild cost is pretty spendy,not to mention field repairs$$$$.if you do go with a turbin,let me know if you need a mechanic because you obviously have moore money than you know what to do with.
good luck :roll: :2gunfire: FWB 603

Did someone call? :)

Yes, I'm still here. Hadn't checked in in a while so was surprised to see all of the activity. There seem to be a lot of people interested in the turbine engine for an experimental Supercub. Maybe it would be useful to get some idea of just how many? There is strength in numbers.

Also, I think we can all agree now that the engine offers tremendous potential in flying the Supercub but that it is probably going to take a little time and experimentation to really figure out what it can do. And a lot is going to depend on the prop which we all seem to have the least information about.

For me, the holdup right now is that I really want to see at least one turbine Supercub flying before I commit to this idea. That's what keeps me sitting on the side lines.

Oh, Betty, about the job ... I'll keep you in mind but if I were you, I wouldn't hold your breath. :lol:

Stephen

aeronca 1
09-18-2004, 11:23 PM
i love you man : :luv2:

geoffmeyer
09-19-2004, 09:59 AM
hey mars man - take it from an a&p, stick with a recip. unless your an overpaid airline pilot with an affection for all things high tech,your waisting your money.rebuild cost is pretty spendy,not to mention field repairs$$$$.if you do go with a turbin,let me know if you need a mechanic because you obviously have moore money than you know what to do with.
good luck :roll: :2gunfire: FWB 603

Did someone call? :)

Yes, I'm still here. Hadn't checked in in a while so was surprised to see all of the activity. There seem to be a lot of people interested in the turbine engine for an experimental Supercub. Maybe it would be useful to get some idea of just how many? There is strength in numbers.

Also, I think we can all agree now that the engine offers tremendous potential in flying the Supercub but that it is probably going to take a little time and experimentation to really figure out what it can do. And a lot is going to depend on the prop which we all seem to have the least information about.

For me, the holdup right now is that I really want to see at least one turbine Supercub flying before I commit to this idea. That's what keeps me sitting on the side lines.

Oh, Betty, about the job ... I'll keep you in mind but if I were you, I wouldn't hold your breath. :lol:

Stephen

That's a good idea. If we want to help propell their Supercub project, you are right, we should get a head count. Call Chuck at Innodyn, and tell him your interest in the Cub. It will make a difference. Here is the number: (877) INN-1200. I am fairly sure that besides myself, there are two others that are building experimental Maules with the Innodyn as the first choice of engines. I don't know if they follow this website, so I'll speak for them & give you a count of 3 (this includes myself)....By the way, I'd really rather have a cub, but I need the extra interior - hope that doesn't get me booted off the cub site! :(

Geoff

leon tallman
09-19-2004, 04:26 PM
there is one under going taxi tests as we speak.

geoffmeyer
09-19-2004, 06:49 PM
there is one under going taxi tests as we speak.

Have they designed a plenum, or are they letting the air flow freely?...Are you involved in the testing?

leon tallman
09-19-2004, 08:36 PM
no i am not involed in the testing. but have talk with with the guy that is. i have seen the aircraft as it was being built .it is my intention to order one nexted summer. there seems to be a new rule about putting the engine in the expermental sometime about a type data thing does anyone know what thats about?

AlaskaAV
09-20-2004, 11:20 PM
Some earlier comments were about having the Cub turbine engine sticking out so far for w&b.. Following are links to two of our Porters, 09Z as a recip and the other PT-6 powered. The basic looks of the Porter with the Astazou is the same as the PT-6 except for the exhaust. To my knowledge everything behind the firewall is the same on both aircraft except for seats. I believe 09Z only had 6 single seats and the turbines had 3 triples plus the right seats up front.
I suspect with my limited knowledge, the Cubs with the Innodyn engine would be on the same scale after all the cawling is installed.

I really like the color of 51T as it flies today.
Markus Herzig, whose links are below, has spent a lot of time putting together the history by serial number of every Porter built.

http://mypage.bluewin.ch/aviationworld/pc6/history/569.htm
http://mypage.bluewin.ch/aviationworld/pc6/history/522-n1409z1.jpg

Mark Cav
10-05-2004, 10:59 AM
The NAVY Testing facility is testing this engine . INNODYN will know more about this engine after the NAVY compleats testing . The operating mannual will be compleat after testing .Current Unmanvehicles have a very low TBO.I personaly think this is one great engine.

Mark Cav
10-26-2004, 09:35 AM
Innodyn just contacted me on center line thrust and refered me to Smith Aviation for this infomation.Innodyn says, they have a Super Cub with a Turbine engine flying already, and every place they have gone there has been alot of interest.

geoffmeyer
10-26-2004, 12:41 PM
Innodyn just contacted me on center line thrust and refered me to Smith Aviation for this infomation.Innodyn says, they have a Super Cub with a Turbine engine flying already, and every place they have gone there has been alot of interest.

If you contact Smith Aviation, I'd love to hear what they are saying. I've heard there are problems with the fuel control unit and the prop - but I'm sure Smith could clear those rumors up.

Geoff

AlaskaAV
10-26-2004, 06:34 PM
Hey guys, if you don't mind, I will stick my nose back in again where it might not be welcome.

I talked to lets say unnamed person from Innodyn and he was telling me about the aircraft that is flying now. He agreed that it responded much the same as I described about the PC6 Porter in my previous posts.

I know it is hard to believe that a Super Cub can perform like the test aircraft does but it does work. Once everything is certified and you guys get a chance to fly one, you will have a big surprise. I know I did when I jumped behind the stick of the Porter the first time.

flattopplayr
11-06-2004, 11:35 AM
If im correct, this engine would not have any lag time or spool up time. It is not a split turbine such as in a garret or a PT-6 engine. It is a single shaft turbine, like in the C-130 Allison Engine. It should be ran at 100% through all phases of flight, thus when you shove the power in all you are doing is changing the pitch of the prop. We have this on the Herc, and boy, you talk about instant thrust!!!!

Would be great on a bush plane!!

Mark Cav
11-06-2004, 12:18 PM
Here are some specks on the Innodyn Turbine over hone design,gear section...10,000 HR,S TBO ,oil filter -special for Turbine( MIL.),igniter-spark(auto),alternater-Nippon,starter-Nikon(Hitach),Computer-Chevy,2-lipp seals(#-buy local), injection-Bosch ,prop -NSI (2 plade) CAP-2000,turbine oil -BP-G-331 8.00@8.00 A Quart every 500 HOURS , Engine Inst.--Tach,EGT-to adjust eng. RPM, Engine-ceramic ball bearings (4)? , Annual inspection -look over turbine blades with scope , fuel pumps -hot rod store 50 PSI .Just about everything you can by locally .

supilot
11-06-2004, 12:26 PM
any pictures or videos of FLYING turbine supercubs yet?

AlaskaAV
11-06-2004, 04:08 PM
If im correct, this engine would not have any lag time or spool up time. It is not a split turbine such as in a garret or a PT-6 engine. It is a single shaft turbine, like in the C-130 Allison Engine. It should be ran at 100% through all phases of flight, thus when you shove the power in all you are doing is changing the pitch of the prop. We have this on the Herc, and boy, you talk about instant thrust!!!!

Would be great on a bush plane!!

That is the way our guys flew our PT-6 Porters. Not sure about the Astazou powered though. I never flew one with that engine. Having that instant power from porp settings as you stated while going into a bush strip sure felt good.

geoffmeyer
11-06-2004, 07:17 PM
There are a few things that we should look at more closely on this engine. Before I say anything further, I'll say I am a huge fan of turboprops - especially the direct drive configuration. I am, however, very skeptical of any new company, and want to hear more positive remarks about this powerplant than negative before I give Innodyn close to $50k - not to mention, trust my life behind it.

I was speaking to a gentleman who did some work for Innodyn. He is no longer with them, and was open to talking about the engine. I seeked him out because I am very interested in purchasing an Innodyn for an experimental Maule airframe. His comments were that the engine was a well designed piece of machinery, but was far from ready to fly safely. He said the fuel control unit was not to their satisfaction the last time he worked on it ( a couple of months ago). He also said the prop would not respond properly - It essentially got "stuck" in a particular pitch, and the only way they could correct it was to slow the engine rpm. I am sure those are just the growing pains of the engine development that will one day be worked out. I have been told by Innodyn, however, that it is up and flying with no problems...so go figure. All I know for sure is that they still aren't delivering an engine.

The other issue is the prop. As I understand, the NSI prop is designed for fast aircraft and has a high speed airfoil. It is also a composite prop. There are pages and pages of threads on this website about the benefits of a long borer prop. The NSI is 74" with a 79" in the works...Also pages of threads on prop material - it seems that most are not in favor of composites for the back country.

So for what its worth, I hope I am wrong about this engine. I sure would like to see it in use on a back country aircraft.

AlaskaAV
11-06-2004, 08:00 PM
Someone correct me if I am wrong and I am just learning about this engine but isn't the basic structure the same unit used as an APU in ground power units and aircraft installed? Needless to say, that does not include prop and am sure the fuel control system would be different since in an APU, it is either inop or at a fixed RPM.

I have talked to one guy at Innodyn who was very open with me when talking about the PT-6 Porters compared to what they were working on and flying.
I got the impression the basic engine was sound, it was the accessories that needed worked on. On our PT-6 Porters, we had a serious problem with prop controls frosting up in the winter. They would freeze up and go from taxi power to full reverse (or just the opposite) with no warning. We had lots of damage on two Porters at Kotzebue because of that. First time I had seen what an aircraft looked like when eaten up by a prop.

irishfield
11-06-2004, 09:00 PM
The other issue is the prop. As I understand, the NSI prop is designed for fast aircraft and has a high speed airfoil. It is also a composite prop. There are pages and pages of threads on this website about the benefits of a long borer prop. The NSI is 74" with a 79" in the works...Also pages of threads on prop material - it seems that most are not in favor of composites for the back country.


Wouldn't trust an NSI prop as far as I could throw it.....oh yah...don't have to as they throw (blades) themselves! :bad-words:

supilot
11-06-2004, 09:12 PM
what happens if the battery shits the bed and your in the middle of nowhere? can you start a turbine without a battery?

irishfield
11-06-2004, 09:19 PM
what happens if the battery !&$# the bed and your in the middle of nowhere? can you start a turbine without a battery?

Guess you could carry a booster pack with you. Dead battery on the turbine would be a lot less inconvient than an empty pressure tank to start your M14P radial !! :bad-words: Mind you I guess if you worked at it your could hand swing the M14P or do the old rope trick if you dared!

AlaskaAV
11-07-2004, 12:53 AM
check out the 368kb video in this link.

http://www.atpcoinc.com/Pages/Requests.html

I dont think this power plant will have trouble spooling up quick enough.
:o

Yes, I saw that video. Pretty impressive. Can you imagine a Cub making a sound like that in some valley or on a small pond somewhere? Hmmm... music to our ears but I wonder if everyone will appreciate it? It might not be a good thing if too many of these turbine Super Cubs are around. In fact, I wonder if noise will be an issue?

As for the spool-up, I would think zero-load would be one thing, but how quickly will it spool up with a load? If you watch the fuel flow figures it takes a little while before those go up. I would think that is an indication of the load they are putting on the engine.

Still, it sounds like one of the design criteria for this engine is quick spool-up. I'll be very interested to hear the results once these engines are in the hands of end-users who can report their findings.

Stephen

Stephen, if you would like a refresher, PM me. You have lost the concept of turbine prop engines (as compared to full jet and recip) no matter what the aircraft and how they are flown. We had Porters with three different engines and each one was flown different. I only flew the PT-6 powered.
I keep reading so many people thinking that a Turbine engine in a cub is flown the same as a recip and that is not true. I spent some time talking to one of the owners of the company that is making the engine work in the Cub and with all the hours flown and after comparing what he is doing with the Cub, it is flown almost exactly as I flew our PT-6 Porter.
I just hate to see you guys going off on a tangent about this engine/aircraft combination. Once the prop and accessory's are worked out, the engine will really be an unbelievable performer in the Cub.

Ernie

FixedWing
11-16-2004, 03:03 PM
Stephen, if you would like a refresher, PM me. You have lost the concept of turbine prop engines (as compared to full jet and recip) no matter what the aircraft and how they are flown. We had Porters with three different engines and each one was flown different. I only flew the PT-6 powered.
I keep reading so many people thinking that a Turbine engine in a cub is flown the same as a recip and that is not true. I spent some time talking to one of the owners of the company that is making the engine work in the Cub and with all the hours flown and after comparing what he is doing with the Cub, it is flown almost exactly as I flew our PT-6 Porter.
I just hate to see you guys going off on a tangent about this engine/aircraft combination. Once the prop and accessory's are worked out, the engine will really be an unbelievable performer in the Cub.

I'm here to learn Ernie. :)

Is it just me or is anyone else noticing how long it seems to be taking to bring a supposedly finished product to market? So much hype. Now so little airplane. I for one would love to know what is going on and what a reasonable timetable looks like.

Stephen

AlaskaAV
11-16-2004, 05:26 PM
Stephen, if you would like a refresher, PM me. You have lost the concept of turbine prop engines (as compared to full jet and recip) no matter what the aircraft and how they are flown. We had Porters with three different engines and each one was flown different. I only flew the PT-6 powered.
I keep reading so many people thinking that a Turbine engine in a cub is flown the same as a recip and that is not true. I spent some time talking to one of the owners of the company that is making the engine work in the Cub and with all the hours flown and after comparing what he is doing with the Cub, it is flown almost exactly as I flew our PT-6 Porter.
I just hate to see you guys going off on a tangent about this engine/aircraft combination. Once the prop and accessory's are worked out, the engine will really be an unbelievable performer in the Cub.


I'm here to learn Ernie. :)

Is it just me or is anyone else noticing how long it seems to be taking to bring a supposedly finished product to market? So much hype. Now so little airplane. I for one would love to know what is going on and what a reasonable timetable looks like.

Stephen

I had a long conversation with one of the guys at Innodyn not long ago. We were talking about how the Cub would operate compared to the Porters. They have one test aircraft flying and it is working out real good but as usual, many fine tunning problems. Sure takes a long time to get something new approved in aviation. Wonder how long it took to get the Beavers and Otters approved.
He couldn't give me an approval date of course. Kind of like "when it is ready".
I just hope I am still around when it is certified. To me, that will be the ultimate bush aircraft for Alaska. A poor man's Porter?

aeronca 1
11-17-2004, 07:28 AM
just buy a porter,for the amount of money your going to spend on this thing,you'll at least get a bigger plane. theres a guy over in monroe, wa. that overhauls them (jim perry,seattle aviation). if any thing he could give you some insight on porters or helio couriers or even widgeons. oh and by the way, im still holding my breath. :luv2:

StewartB
11-17-2004, 11:51 AM
I hope Innodyne pulls it off and brings their little turbine to market. All of our piston engines will be instant antiques. Well, really they're antiques now. We'll just finally have to admit it.

SB

AlaskaAV
11-17-2004, 12:17 PM
I hope Innodyne pulls it off and brings their little turbine to market. All of our piston engines will be instant antiques. Well, really they're antiques now. We'll just finally have to admit it.

SB

The guys from Innodyne really believe it will work. The basic engine is solid and the Cub frame is solid as we all know. Now it is just getting the mounting hardware finalized and then getting the correct control systems worked out and than the big thing, the prop. I understand that is were the holdup is now. Getting the prop to work with available boxes to work together. We also have to understand Innodyne does not have the financial backing as New Piper and Cessna does.

As Aeronca1 said, buy a Porter but what bush pilot needs a ten passenger aircraft to play around with. Just think of the insurance costs per seat.
I wonder what a wide body Cub with barn door flaps and leading edge slats would do with Innodyne power. Fence at 30 mph and flare at 25 mph? Land into a 25 mph headwind, ground roll zero. Interesting idea.