LLE and Fuel tank

[alanr]

Lowell and Josh, thanks for the input...all food for thought.
Seems to me the case is not totally clear cut either way so whichever way I go, LLE or not, I will probably wish I had done the other at some point down the line!

Alan.

[DesertFox4]

The LLE will be on my 7SS. I've flown two Kitfox with it installed and can tell the difference. Problem is no one has had time to do in-depth comparisons between with and without. I know that the wing behaves differently, better, with. Wish I could quantify my impressions with real data but alas, I can't. Just know I've flown a few "stock" Kitfox in my day and a couple LLE's. I'm going LLE.

As mentioned early, Harry Ribblet designed the wing for the model 4 ( which is the same wing used on the 5,6,7,& 7 SS). If you don't know the name and fly a model 4 on up, you should know his name. He's the reason we all have such great flying and handling aircraft.
His design had the "leading edge" as now available in the LLE. Denney Aerocraft and SkyStar never used the leading edge treatment for whatever reason. Maybe they couldn't figure out a way to make it work without incurring the problems resulting from the wing flex. Maybe monetary reasons. Dan Denney has it on his private "super stol" Kitfox but has aluminum instead of fiberglass. He has deformation from the wing flex but other than the fabric wrinkling he loves it. That says something right there.

Now that the flexing wing problem has been solved by the LLE, it completes Harry's vision for the best performing wing for our particular aircraft. We all know the Kitfox flies great without the LLE and thousands of aircraft flying don't have it. Also as mentioned earlier, maybe V.G.'s will have a measurable effect on this wing. Not sure yet. I think after some time and with many builders installing it, we may see in the future that those aircraft with the LLE may be in more demand over the Kitfoxs without. Of course my crystal ball has been a little off in the past.

I love the look of the LLE Kitfox wing too over the scallops.

[alanr]

Steve..Thank you for the explanation and your experienced input. So for today it looks like I will be going with the LLE even if it does break the bank!

Also following your build with very keen interest..simply great!

Alan

[Flybyjim]

So how does the LLE work with the flex of the wing and not show up with wrinkles in the fabric as you indicated the aluminum does?

[HighWing]

A note on wing flex and aluminum leading edge skin deformation. One of our buddies from the Fly Idaho days had a Rans s-7 with aluminum leading edges. His would occasionally have the aluminum cave between one of the ribs. We would call it to his attention and he would grab his wing tip and with a grin, shake the wing and the bubble would pop out.

When I decided to to the aluminum leading edge, it occurred to me that it was on the ground that the aesthetic imperfection would occur and be visible. In the air, who knows - aluminum or composite. And I repeat, until someone mounts their GoPro looking outward on the top of the wing, who knows what the top surface looks like in flight with the outboard end flexed up.

I planned my installation in the ground configuration. My Rotisserie was modified to support the wing at the lift strut brackets. The wing would then hang as it would when on the fuselage on the ground. The only thing I would do differently if I were to do it again would be to put some weight in the tanks as they will warp the spars a bit when full. i will occasionally have s small barely visible four inch diameter dent near the outer edge of the third rib left side. It is impossible to see when on the ground, but if you look while filling the tank it sometimes appears.

For what it's worth, I rechecked my numbers and got a four mph lowering of stall speed at power off - 40 mph clean. These numbers are relative to my first Model IV.

At 4500 RPM, I could get 30 mph before stall and at full power 28 mph with no wing drop. (The "interesting" in my previous post referring to full power stall has always been previously referred to as violent. I was asked to do a full power stall during a BFR once. I did it and that once was enough for the CFI.) I procrastinated big time during Phase one on this airplane for obvious reasons.

[DesertFox4]

Good stuff Lowell. More info than I could give the group. All I could tell was that the wing behaved better in all speed ranges. Felt more reliable if that makes sense.

I'll do that GoPro thing but probably not for a while yet.