• If You Are Having Trouble Logging In with Your Old Username and Password, Please use this Forgot Your Password link to get re-established.
  • Hey! Be sure to login or register!

Supercub Thrust Line

20' is about a plane lenght. Maybe Groundloop could tell us how his plane is set up and how much it weighed at the time. I can't picture my plane getting off in 20' configured the way it is now.pak
 
GroundLoop,

Any chance you would be around Lake Hood during the Trade show next weekend? I would bet you could get a pretty good audience if you were to put on a short "demo" and let some of folks who will be attending know when so they could watch.
 
I just got back from flying. The 100mph figure on 31" tires is correct. It sure trims nice (I can't wait to try it heavy, like the LEES it will probably make the biggest difference in the worst scenario). It definitely floats a lot more in ground effect when landing. I will be on floats tommorrow. Hopefully, I'll get a chance to fly it and give some more feedback.
PAK, The plane probably weighs about 1245 with the cago pod, yesterday it had 25 gals fuel and me 205 lbs, 15 lbs crap in plane. Cub is legal.
 
When I talked to Mark, he said that the lower cowl channels have to be replaced with longer ones. I can't remember (he told me) if these were included in the STC or not. The machining work on the replacement lugs is pretty impressive.
 
sorry

Retraction, Sorry guys didn't intend to hurt or insult anyone. But I do
stand by what I said about the price of any good product. We spend
a lot on our planes and I want to save any where I can but everyone
has to make a living. I havn't seen anyone getting rich with the STCs.

PS Mark I washed my mouth out with soap and I won't say get a life
any more. Wayne
 
For the first time today, my cub felt like a husky on floats. Anyone who has flown a Husky on floats can tell you how impressive the first 2-4 secs. are. It surges you onto the step, and you get the feeling like it will fly regardless if you roll it onto the step or not.
I really think it would be better if a real pilot like mvivion could feel the mod, maybe I am too easily impressed. Afterall, the Husky left a large impession on me!
 
Gezzz....this ALL sounds pretty impressive, I have read all 5 pages w/ great interest!

My hats off to anyone who charges head-first into the FAA for their blessing, good jobs guys! The STC process isn't getting any easier with time.

I've been flying an ol' red & white cub for many years, through the years I've seen many "new fangled" idea's come and go. True some things are a real improvment to the best plane ever built, however the reality is that most of the mods for a Cub aren't what they're made out to be. With that said I'm skeptical, sure...I'd like this ALL to be true, but time will tell.

Reading through all 5 pages I've read things like "reduces ground roll by 30%". Well, lets talk about that. You take a good Cub, light weight and ready to go for a short field take off, put the whip to it (no wind, 1 guy full fuel, some weight), whe the tails comes up this is ALWAYS an indication the plane is ready to fly...this will happen in about 300', give or take. IF the take off roll is reduces by 30%, this would 90' less. In other words this same take off would be 210', instead of 300', sounds like a lot to me. Espesially because a Cub won't fly until the tail comes up, on big tires. Interestingly enough, the tail is the first thing you loose at low speed also. Can ANYONE stall a cub, on the ground, during a landing, and MAKE the main tires touch first? Of course not...the tail flys first, it also stalls first.

I have also read things like "while hanging on the edge....its quite a dance" WHAT??? What do you mean>? A Cub is THE most forgiving airplane in the world, it will always tell you when its' about to stall, and by the way...it is hard to make a Cub really "stall". You can take a Cub into a 500 fpm "mush", however they have to be loaded just right, and a fellow driving knwoing exacty what to do to "MAKE" them stall...I mean break-over and stall like a spam can. All this talk about "better" landing performance....what exactly is better??????????

Next in line from point of view is the trim. The trim on a Cub is a good indicator of how well you have your load within the CG limit of the machine. In other words, if you're trimmed all the way forward, and still pucshing forward on the stick, most likey you're loaded to far back, to heavy, or both. In this case, you'll want to fly it on, fast, with no flaps. Why...>? Because you'll loose the tail (stall) if you slow it down too much. Once again the tail is the indicator of whats going on.

So......if the thrust line is "improved" to be more inline with the plane, this could be compared to starting your short field take off with one notch of flaps. In other words if you set a notch of flaps at the begining of your roll you have induced "extra" drag that only hurts you. On the other hand, if you reach down and grap a "handfull of flap" when the tail comes up you'll pop-off and can easily hold it in ground effect till you get some speed. I can relate to this "improvement", however how much are we really talking about?
I'll stick my neck out some.....Is this the same as VG's?? ALL the performance gain you get from VG';s.???? I can fly cirlces around guys with all the doo-dads on thier wings, Take off and land shorter to. plus I'm willing to put my money where my proposal is too...
Maybe this will make a REAL improvement, at minimum a lot of guys put a lot of work into making our Cubs perform better and for this...we shoudl all buy them a cup of coffee every time we see them...:)

Good Flying...>Byron
.
 
Concerning the trust line mod.
I purchased the mod from Mark last week $1,800.00 plus $200.00 install. pa 18 160 hp stock wings w/vortex. My numbers where 34 stall, 94 mph at 2500 rpm, 80 mph @2250rpm ,70mph @ 2150 rpm.

after stall 31mph, 98 mph @2500rpm, 80mph@ 2100 rpm, 70 mph@2000 rpm .
Overall signifacant improvment in take preformance that also transfers over to short wheel landing capabiloties.. more so than stock configuration.
since the install I have flown appox. 30 hours to date.
I have several Cubs and will plan on doing the mod. to all three.

JMF
 
Well we put Mark's mod in my SC last night and have only put about two hours on it since. The first noticable change is 110mph indicated on the airspeed indicator verus 100mph before in straight and level flight with light winds and 2500 rpm.

It also seem like there is less need for trim to compensate for the leading edge slots when landing light (i.e. no big load of gear in baggage) but we have to fly more to have the definitive statement on that.

We also noticed more elevator authority both in straight and level flight and also in t/o and landing. We need to fly that end of the envelope more and will have more to say after that.

Bottom line right now is an honest 10mph increase in airspeed and more responsive elevator. Mark's got a good thing going. We'll have more to say soon. Especially after we fly it back from ANC to Washington following the trade show. Looking forward to seeing everybody at the show.
 
I got to play with it a little more on floats today. I noticed on my airplane the speed differences at lower rpm's were much more dramatic. It seems that it is very difficult for my cub to go faster than 105mph on floats as currenly set up. I am getting the impession that it will be very fuel efficient. At current fuel prices it may pay for itself in 10-20 years or so.
It definetly lands better now than when I had the old 160hp up front.
Does anybody know what speed a 180 hp cub on floats with a cruise prop will do?
 
Any update on this? Is the PMA thing resolved? Any time frame for general availability?
 
update

Hi Gerald

I have to submit a revised manual this week. MIDO finished their final on site inspection last week and they were satisfied. I suspect we will have the PMA and be able to ship kits within two weeks at the latest. Over the last year that we have been testing, we have had three cubs this mod has not worked on. Two of those cubs have been in the last couple of weeks. Although it was disappointing--it has given us an opportunity to figure out the reasons why. These two cubs had some serious fuselage problems. Briefly---no angle of incidence and tail posts up to an inch and one half above the horizontal reference line. I will give a detailed report before these kits are shipped. We are going to come up with some simple
measurements that can be used in the field with a digital level and stringline to identify these problems. All other cubs performed as expected. Please bear with us on this startup and all info good or bad will be reported. To sum up--if you have a straight fuselage the mod works, if the mod doesn't work--fuselage problems. This opinion will become clearer as customers report back results.

Thanks

Mark
 
Ak - where at BigLake are you located? I am over in Wasilla and would like to come look. Thanks.
 
I just had a EI fuel flow installed and the A&P told me that fuel line was stretched from the mod to an uncomfortable degree. I just thought those who are about to install might want to check thier fuel lines after.
 
da lug

Hello Mark! Thanks for your efforts getting this mod approved and installed on Gunnys plane. It has made a noticable difference in his indicated air speed and the A/C does seem to be lighter in pitch with more authority in the three point attitude. Sure enjoyed the demonstration that Billy put on with his Penn Yan Aero Cub, and I hope to be able to fly like he does when I grow up. Can see where they will benefit even more from this mod than the stock mount. Thanks for being such a wonderful host Mark, and good luck with your endeavor, if we at Air Classic can help, please allow us. Fly low. avoid the radar. Mike Buitterfield
 
Thanks for the report Ground Loop

That was my fault on the fuel line. I checked it when we were doing throttle and mix controls. If your mech felt it was wrong( I am pretty sure I know who he is) then I am sure it was. He is quite a good mech. I appologize for that. Thanks for catching and reporting the problem.

Hey Mike --Thanks for the offer. Life in the fast Lane at Big Lake! It was quite a pleasure meeting up with the both of you. Really enjoyed it. Nice Cub. Can't believe what this website has done for getting the Cub community together. Billy is another story alltogether! Some of the readers know him in the all Black Penn Yan Cub at Lake Hood. He said he would post results if I would help him or if someone would show him what a computer is. Maybe if someone runs into him in Anc they could post for him. Also I have just returned the Test Cub to the owner at Lake Hood. Hopefully he will fly it on wheels and post.

Some full AC views of what the ThustLine looks like on the Penn Yan test Cub have been posted.
http://www.supercub.org/gallery/view_album.php?set_albumName=supercubs&page=56

Mark
 
Just an update. We are still trying to come up with some measurements on these fuselage discrepancies. If there is anyone in the Anc/Valley area that thinks they have a straight cub interested in this mod give a call. The installs out at Big Lake are guaranteed. If you don't like the mod we will take it back out and I will cover the install and removal so that it costs nothing but your time. We have received the PMA but are not prepared to ship these kits all over the country untill we can come up with some solid consistent measurements on the fuselages that work. Again thanks for your patience while we sort this out.

Mark 907-232-5951
 
Gary Bishop of Palmer Air installed the Thrustline mod. He has a 160hp cub with Micro VG's and a helicopter AS. He was kind enough to send me a letter with his results. There are a half a dozen other pilots that have said they will be posting results. Nothing yet I know---but hopefully soon. Here is the link to the new album with Gary's letter.
http://supercub.org/gallery/view_album.php?set_albumName=album59

Mark
 
Put the thrust line mod in today, did some testing, and thought I'd give some initial results.

Right before the change, we stretched a tape out on the runway, and measures max performance t/o and landings. Ran the plane into the hanger and did the mod as quick as 3 guys could do it. Took it right back out and measured max t/o and landings again. If anything, the head wind was definitely higher, and the temp cooler during the first test, so no environmental advantage could be given to the mod.

Take offs were definitely shorter with the mod, no question. Landings were also shorter right out of the box. After making a few landings, my spotters told me I was floating 10-15 feet past the touchdown line, and I made some adjustments, and started really cutting down the landing distance.

The air was to rough tonight to get any good cruise numbers or AOA, so will report those later.

Initial impressions on the kit-

The machine work on the parts is flat beautiful...Those shinny parts look completely out of place on a old work Cub. The installation instructions and paperwork is excellent and in order.

The tail seems lighter. In this Cub on a max performance take off, (stock), you would hold the brakes and add full power then use a lot of forward stick to lift the tail. Release the brakes and the tail would fall, so you had to ride the brakes for the first 10 feet or so to keep it up. With the mod installed, the tail starts to float up at about 75% power, lift it up high, release the brakes and it stays up. I have a feeling this has a lot to do with the shorter t/o distance.

Climb performance seems better.

Prop clearance is better, (sorry I didn't measure it Mark).

The cowl is higher, which does decrease forward visibility, but it's no big deal. I'll definitely take the performance trade off.

There is a better "feel" when slow. It's more comfortable right on the edge. When in straight and level cruise, the plane feels cleaner, like it is not fighting itself.

It is all good, just wanted to give some initial impressions. As you fly a mod, it gets hard to remember what it was like before, and comparisons get fuzzy, so want to get something in print now. If the amount of phone calls is any indication, Mark is really biting his nails on this, but I don't think he needs to, it works. I'm as sceptical as anyone when it comes to the latest miracle mod, but I honestly think this may rank up there with the Borer prop and Micro VG's when it is all said and done.
 
Can't tell you how much I appreciate the work you went through to test the mod for us Mark. Nail biting is right. I have been promising results from folks flying the mod but I have not been able to deliver in a timely manner. Also Mark---yours is the first Lower 48 stock cub install. This endeavor is not insignificant to us---I suppose it's kind of like watching your child go off to college. We are attempting to let the mod's results sell the product and your tests today helped us in that direction. I am sure that a few more folks will be interested in getting this mod installed which just means more results to post. Hope you don't mind me camping on your airport with no airplane---making reservations this week for the NH flyin!
Looking forward to meeting you and the other Cub pilots out that way.

Thanks

Mark
 
zero thrust line mod

just thought I'd add a comment on Mark's new mod.I have a fair amount of time in supercubs,mostly off airport so I'm not a novice.I flew my partners 180 hp.cub before the zero mod and after.It is really a dramatic improvement.There is a gain in speed of four or five mph,but the impressive thing is how much slower the approach speed is.And not dragging it in nose high with power.It is a very comfortable attitude,and corrections are made with small power adjustments.One more thing,I have known Mark for more than a few years,you wont get a bs story from him,you will get good support.AKL21
 
Just wanted to comment on Marks Thrustline mod.

We installed the mod on my 160 cub a few days ago and prior to installation I did a base line flight to be able to tell the before and after difference.
I could go on and on about the improvements it made and they virtually mirror the previous comments. The most noticeable was the low speed handling and a 4-5mph top speed increase.
I have owned a cub for 30 years in alaska and been flyinging 300-400 hrs per year as a guide. It is a rare day when landings and takeoffs are not in rough areas with heavy loads.
The 2 most recent mods installed on my cub are Micro Vortex generators 5 years ago and the Thrustline mod last week. I do not know of many mods that you can hold in one hand that do more than these for the performance of a cub. The safety margin has definitely increased for for what a cub does best.
After installing the mod and flying the cub I walked up to Mark, who was on pins and needles, with my most disappointed look I could muster and he asked if we should take it off, I told him after the fist fight and started smiling. This mod works and his grantee of taking it off if it does not work should tell you a little bit about what sort of person Mark is. Congrats Mark on your great mod.

Tundrafox
 
I don't have the mod on my plane (a 12) but if I had an 18 it would have been done already!

I can attest for Mark's integrity and I am sure glad he had the tenacity to see this thing through! (way to go Mark!)

Tim

PS: it was darn hard to keep this quiet for the past year +!!!!
 
For speed and landing, I would give the nod to the thrust line mod. For take off performance and rate of climb, especially with a load, the LEES is the ticket. They do different things and are synergistic together.
 
Back
Top