Leading Edge Skin.

[BB]

Hi
I am recovering my wings. Considering extending leading edge aluminum back along the top of the wings about 10-12 inches. Some very high time and experienced cub pilots at the hanger say its a good thing. Some say it increases cruise speed, some say it "flies better", and maybe even will fly a bit slower. It certainly will make the wing a bit more rigid. It also keeps the fabric from drooping down between the ribs on the top of the wing. The problem is it will add seven pounds per wing. I started this project trying not to gain any weight at all. I fly a stock wing with BLR vgs. Any comments would be appreciated.
Thanks
BB

 

[cub12]

all smith cubs and now TCOW cubs have it . i like it. even with the 101 fabric their is no fabric droop between the ribs.

 

[Snert]

Building an airplane is like dieting, you put weight on in pounds and take it off in ounces.

 

[Bill Rusk]

From a previous thread....


Extended Leading Edge skin(ELES)

I spoke with John Roncz, probably the leading airfoil engineer in the US. He is the one who has designed all of Rutans airfoils and others like john Sharp's Nemesis (dominated Formula 1 for many years). The guy is no yahoo, he knows airfoils and aerodynamics. I asked him about the Extended LE skin (ELES). After a long dissertation on the 35B airfoil origins etc his response was that he did not know of any wind tunnel tests, so take it with a grain of salt, but based on what he knew about airfoil performance, he did not think it would have any positive affect. At high AOA the air is only attached at the LE edge of the wing forward of the front spar. Thus any airfoil deformation aft of the forward spar is in dirty air and basically has no affect.
All that said, the ELES, remains an unknown because we have no wind tunnel testing, and furthermore we must add the VG's to the equation.
It does add rigidity, and strength, to the wing. Makes it easies to clean the frost off, and minimizes the scalloping. But it adds weight, 4 to 6 pounds.
Steve Tubbs, Jerry Burr and John Roncz all have expressed reservations as to its effectiveness at high AOA. Others swear by it.

Bill

 

[mike mcs repair]

I love it on my jobs, but thought I couldn't get it approved anymore(because it stiffened wing), so have been unable to add it for years.... unless things FAA wise changed.. which some things have......

If i could do it I would.....I haven't asked FAA in years...

anyone getting it field approved in last couple years?? got 337 you'd be willing to share???

I had always heard it was tested in a tunnel way back when, but don't have backup on that...
**********
scalloping is **HUGELY** dependent on the initial fabric shrinking... you MUST go side to side full wing length across area that scallops(behind leading edge) in ?strips? never front to back on initial shrinking.... and i usually start from center out twords ends on every thing, you can make it pretty nice if you are careful and think.....

 

[Longwinglover]

Here is a link to "THE" NACA test report. The gist of it is that the scallops in the fabric between the ribs has no effect on the lift produced by the wing.

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930087647_1993087647.pdf

John Scott