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Lowrider LSA

Well, I've tried 4 times to post a picture...the gods apparently aren't with me tonight. I tasked #2 son with building an engine mount so we could tear down my recently purchased engine. He came up with a better idea...bolting a 2x12 under a piece 3/4" plywood bolted to a pair of saw horses. That give a solid mount for the crank flange and lots of area to place things as they come off the engine. A quick trip to Home Depot sourced a 4x8 sheet of melamine which should be easier to clean up than plywood. Some screws and bolts and my engine crane and the engine is ready to start the tear down.

I tore the oil filter apart and ran a magnet thru it and came up with nothing in the way of metal. We'll see how the inside looks as it comes apart.

I had a talk with a few folks about ignition and the suggestion was replace the mags with a Light Speed system....save weight, get more fire and still have redundancy. Any thoughts from those using that system??
 
Or P mags, electronic, but perhaps a little less complicated. Search will provide all the useful data.

Bill
 
Thanks gents!

I looked at P Mags but I ended up with an H2AD with the single drive so that pretty well rules them out. One of the reasons I went with that engine was the ability to use electronic vs. mags which gets rid of one of the perceived problems with the H2AD. There are a number of auto electronic ignitions that can be programed to work on an airplane engine as well as the Light Speed system. These will also interface with electronic fuel injection via throttle body to further enhance engine performance. Not sure I'm ready to go there yet but it is an option. Ellison throttle body looks like a better option.

In my youth, some many years ago, I built "hot rod" engines to make 4 wheeled vehicles go fast and it just seems there should be a way to get better performance from a 320 cubic inch engine even without increased compression or stress to the engine. Better induction, exhaust and ignition should come up with a little improvement and still maintain good reliability.

Thoughts?
 
Lowrider, As an old Gearhead who's been bitten by the aviation bug, I too struggle with ways to get better performance from 1940/50's technology aircraft engines. Volumetric efficiency is the key, but the design of these engines is the roadblock (in my opinion). Stroke it... the 0-340 engines produce good power for the inches. Port N polish to let it breath, but the valves get in the way and you can only do so much. Electronic ignition is a must! And as you mentioned a better flowing exhaust. Sky Dynamics has a great induction system, just save up your money their not cheap. So nothing new to tell you just My 2 cents.
 
Hi low rider, the h2ad is a somewhat odd engine in my opinion. The case and sump are a lot different then an a2b or e2d ect. The yellow sump pictured is a d/e model sump and the other is an h2ad. They are a good engine, just different.
 

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Clint makes a great cross-flow exhaust system. Quiet too. I've got one on my O340.

And I would agree that electronic ignition is an excellent way to go. Timing that changes as needed rather than lawn mower technology ignition means more power on less fuel. I have Lightspeed and it has been trouble free.
 
Steve,

Right on!! Why can't we just slap a set of headers, a new intake and a Holley double pump on it and mop up the competition!

Clint,

I thought long and hard on the H2AD and I've found a first run engine that looks to be in great shape. I had one in a '79 C-172 that I flew all over southern Alaska, all the time wishing it was a SC and it was a strong engine that should give my LSA build the performance I'm looking for. I know they are a sorta unique engine and parts are getting hard to find but with a good build I think it will serve me well. I have my eye on those exhausts you guys build!!

Spinner,

I've thought about stroking but I wonder if it really makes a big difference? Guess you are happy with yours. BTW, I was in your neighborhood a few weeks ago taking my wife to the buffalo grounds. I keep thinking I want to do a canoe trip down the Flathead.
 
I was just over on the J-3 site and noticed some folks are using Warp Drive props on their 0-200 powered cubs so I went to their site and was a little confused what their max horsepower rating might be. Then I remembered that Ivo Prop made a higher performance prop so I went to their site and they apparently have props that will handle up to 700 HP, are ground or air adjustable. Here's info from their site:

IVOPROP Magnum Propeller
For engines up to 700 hp
30"- 90" pitch range
58"- 76" diameter ​
  • in flight or ground adjustable pitch
  • for engines up to 700 H.P.
  • carbon/graphite fiber/composite
  • 30 day money back guarantee
  • all blades protected by stainless steel leading edges
  • light, strong, efficient, quiet, smooth
  • size between Ultralight and Magnum
  • good for fast planes - scaled down Magnum shape

  • unique pitch adjustment design no protractor or pitch blocks required for ground adjustment
  • low drag hub
  • beautiful high gloss black gelkote finish
  • easily and quickly converts from 3 blade into 2 blade configuration - giving you a spare blade
  • blades individually replaceable

Are there any being used on Super Cubs or the like and if not, why not? I'm pretty well sold on the Cato prop but the ability to ground adjust and tune them to what you're doing with the plane such as adjust to a cruise prop when you are not needing climb performance is attractive....or am I missing something?
 
Lowrider said:
Spinner,
BTW, I was in your neighborhood a few weeks ago taking my wife to the buffalo grounds. I keep thinking I want to do a canoe trip down the Flathead.
Click to expand...

let me know the next time you're coming this way and I'll show you around. We do a lot of floating on the Clark Fork too. Not so much on the Flathead.
 

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Same here!! We spend a lot of time on the big lake at the mouth of the Clark Fork around Johnson Creek as well.
 
Lowrider, I may be wrong, but I don't think the IVO folks want you to use their propeller on a direct drive big bore engine. Maybe the small Continentals are OK, But I think the O-320 and O-360 Lycoming are not recommended.
 
Flap ribs

DSC_0017 (1024x683).jpg

I spent the better part of the day making the nose ribs for my flaps. I have sore hands from cutting out the pieces of aluminum but I'm down to only finish work for tomorrow. I will take on cutting and bending the flap spars over the weekend and maybe start the layout...but I'm pretty sure I will hear the call of "better go bear hunting" so I'll lose some time...oh well....so many things...so little time!!
 

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Lowrider,
Looks good. Did you decide not to have a slot between the wing and the flap when they are down? That lower leading edge shape will spoil the air flow, if you do have a slot.
 
No Sir, I still plan on using the bottom hinge location. I thought the gap is supposed to enhance air flow over the top of the flap when it is down. It seems to me the bottom front edge will have little effect on the air flow on the bottom of the flap since it is already in "dirty air" due to the flap being lowered into the air flow under the wing. First 20 degrees gives lift then the next 20 degrees are mostly drag anyway...right?

Where did I go wrong here?
 
The flap is a wing. The flap needs to have a nice clean airfoil shape like the wing. Your shape will produce a flat leading edge which will generate turbulence thus destroying the smooth accelerated flow through the slot. Look at a Super Cub, a Cessna, a Citabria or any other type of plane which has flaps. They are all basically the same, curved, not flat.
 
I took a quick look at Bugs' build site and best I can tell the flap looks like a wing as you describe with the leading edge flat on the bottom and rounded on the top. I want to do some more looking before I redesign my nose and the false spar contour to allow for the roll down of the flap. How much gap is appropriate?

The biggest reason I went with the Riblett wing is the top end speed advantage over the Cub so I really need to think this thru before I make a change that will impact cruise speed to gain less stall speed/better slow speed handling. Everything is a trade-off I suppose. I'm thinking the flaps will give me a lot more flight options regardless of the gap or not.
 
Sky,

I understand why the flap gap allows the air to flow better over the flap, however,if I remember correctly, when I had a Horton STOL kit put on my 172, years ago, it included flap gap seals on top of the wing to keep the air attached when the flaps were down. The kit did improve slow speed handling but I don't know how much the gap seal contributed overall. It also had a stall fence which Dave Calkins seems to think has no effect. Still thinking and looking.....what size is the gap on your Cub?
 
Lowrider said:
So it should be like the wing leading edge and not round?
Click to expand...
Yes, a similar cross section. You could just make different flap nose ribs.
Lowrider said:
I took a quick look at Bugs' build site and best I can tell the flap looks like a wing as you describe with the leading edge flat on the bottom and rounded on the top. I want to do some more looking before I redesign my nose and the false spar contour to allow for the roll down of the flap. How much gap is appropriate?
Click to expand...
When the flaps are up there should be no gap on top. The bottom will not be critical. When the flaps are down, the upper gap will be roughly 1/2".

Lowrider said:
The biggest reason I went with the Riblett wing is the top end speed advantage over the Cub so I really need to think this thru before I make a change that will impact cruise speed to gain less stall speed/better slow speed handling. Everything is a trade-off I suppose. I'm thinking the flaps will give me a lot more flight options regardless of the gap or not.
Click to expand...
You will not see a cruise speed loss with a gap under the wing with the flaps up. A Cessna test pilot once told me that when Cessna installed the gap seal on the bottom of the 206 wing, that there "might" have been 1 knot difference in cruise speed. A 206 will cruise a lot higher than your plane so, there would be more obvious speed change on the 206 than on yours.
 
Lowrider said:
Sky,

I understand why the flap gap allows the air to flow better over the flap, however,if I remember correctly, when I had a Horton STOL kit put on my 172, years ago, it included flap gap seals on top of the wing to keep the air attached when the flaps were down. The kit did improve slow speed handling but I don't know how much the gap seal contributed overall. It also had a stall fence which Dave Calkins seems to think has no effect.
Click to expand...
I was just looking at some pictures today of a Horton 172. There was no additional gap seal on top of the wing and nothing on the bottom. I agree with Dave, those fences are just for looks.

Lowrider said:
Still thinking and looking.....what size is the gap on your Cub?
Click to expand...

Flaps up- nothing on top and 3-1/4" on bottom.
Flaps down- 1/4" on top and 5" on bottom.
 
Thanks Sky!!

I need to look at some more cub drawings to get the geometry of how the hinge and flap attach points are situated to allow those numbers to occur. I have Northland drawings so maybe that is the best place to start. I have an idea in my mind how they should work but can't picture it. I have a layout that should work using my LSA aileron hinges that were just moved down to the attach on the bottom of the flap. I'm going to make some cardboard cut outs to see if that will work. I thought the top gap would be something like 2" or more to allow that air to flow like the double slotted flaps only with just one flap...back to the drawing board.
 
I looked at 2 super cubs and they were not the same on the measurement from the bottom of the flap spar to the centerline of the hinge bolt/pin. I looked thru the North Land drawings and can't find a measurement. Does anyone know that measurement please? BTW, without an index, the North Land drawing are not very user friendly...IMHO.

Sky,

I think I have way to make this work out without a major redesign of the flap system. I can re-do my nose ribs to look like a profile of a hollow point pistol bullet...i.e. a round nose with some of the nose cut off to be able to clear the rear spar without a false spar. This won't change the geometry but will allow the air flow over the top of the flap as you mention.
 
Just make sure that the leading edge of the flap is curved without any corners or sharp edges. A sharp edge can/will cause disturbing air flow through the slot and thus prevent smooth air flow over the top of the flap thus loosing some of your lift. Remember you are trying to generate smooth accelerated flow through the slot and over the top of the flap. Turbulent air = loss of lift.
 
I think I have the concept. Moving the flap hinge back to allow for a full aerodynamic shape will put more up load on the hinge when deployed requiring a heavier hinge and backing plate on the rear spar and I'd rather not do that. I've upgraded the hinge attach points on the rear wing spar to .032 on the rear and .063 in the front of the spar which should be plenty heavy to take the load of the larger flaps...but I don't want to push it too far back from the spar. Hope this makes sense.

I just checked a Legend Cub and their flap hinge is very close to 1 5/8" below the bottom edge of the flap. It was on amphibs and pretty hard to reach with a 4' ladder. Does that sound correct?
 
Thanks Sky!

I have measurements of 1 1/4", 1", 15/16" and about 1 5/8" so I guess there is not a standard at least on the 3 Super Cubs I checked. I'm going to use 1" and see how that works. If they don't work well once I get into the air I can make new hinge mounting brackets with a different mounting location since they will be bolted into the flap spar with nut plates. I may put an inspection plate in the bottom of the flap to allow access and use bolts and castle nuts instead. They will attach via rod ends so there is adjustment there too.

Next issue...I'm thinking of using 0.020 to cover the flaps instead of fabric. I know there is a weight issue but the question is will the increased strength of flush riveted alum a good trade off? I guess I could use 0.016 instead to save a little weight. Rib spacing is 11". I'm thinking of using a fluted trailing edge something like Cessna's. Any thoughts?
 
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1" is a good number.

I would cover the flaps with fabric. There is a lot of prop wash/pounding on them which could and does cause cracks in the aluminum. Particularly if it is thin. The fabric is flexible and will not crack. Any thing in the prop blast takes a beating. Of course the basic structure needs to be designed with this in mind.
 
Good points! It'll also give me some practice for bigger stuff too. I've never done fabric before...so that that will be a learning process. I'm using the Stewart System.
 
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