ES wing incidence discussion
Posted: Sat Oct 21, 2023 5:40 am
A question was asked by Matt Candelaria on LancairTalk about whether right wing heaviness was common in ES's and whether he should consider lowing his right flap a bit more to get rid of it in his plane. I'll repost my answer here, as someone here is probably more knowledgeable than I am on this.
I wondered why my plane was right wing heavy. I used a smart level to check the washout in the left and right wings. Washout is the amount of twist that makes the angle of incidence lower at the tips than at the roots. The reason for washout is that we want the roots to stall before the tips. Our wings are supposed to have 2 degrees of washout. I measured a few tenths of a degree more washout on the left wing than on the right. This was "fixed" by lowering the right flap a bit.
There were something like 10-12 ES kits in some range kit # range that I don't have at my finger tips that had an even bigger difference in twist between the wings. Some of the builders of those planes used something called "eccentrics" to alter the relative incidence of the wings to eliminate the problem. I am not sure how they work, but there are Lancair ES folks out there that are familiar. (I have emails with posts on the old Yahoo ES list I could share, and perhaps some folks on this list also know.) Some builders went back to the factory and de-bonded then rebonded their wings to get the washouts equal and eliminate the eccentrics. I recall someone mentioning that that Tim Ong (he was at Lancair at the time) thought that was over-kill because the eccentrics largely eliminated the issue, maybe at the cost of a bit more drag, but some guys went back and re-bonded their wings anyway.
I am not an expert, but your right flap doensn't look any lower than mine, maybe less lower, though its hard to tell from the pics. However, it looks to me like you have more aileron trim in straight and level. You might want to consider lowering the right flap a bit more, though I suggest talking to the guys at Elite Pilot Services or some other knoweledgeable folks about this. Have you tried checking for a washout difference? If the difference is big enough, you might want to consider the eccentrics that others have used (maybe some still are using them, I dunno). I don't have more info, but JC (EPS) is on this list and might comment if he's aware of the issue, and like I said above, I could pass on relevant posts on the old Yahoo ES list, which discussed this issue at some length.
Matt, my right wing was a bit heavy on the first couple flights, and aileron trim couldn't take it out given where that was set. We adjusted the right flap down nearly a degree to eliminate the issue. That straightened things out, though I realize I have a bit more drag than I would if that adjustment weren't necessary.Hello all,
My ES pulls to the right. It has done this since I got it 5 years ago. I am wondering if this is normal. I seem to need a lot of aileron trim to keep it level. I have pictures showing how I adjusted the right flap down. It seems to have helped a little. Is there anything besides adjusting the flaps that I can do to get it to fly straight? Do I need to be more aggressive with adjusting the right flap? Here are some pictures:
I wondered why my plane was right wing heavy. I used a smart level to check the washout in the left and right wings. Washout is the amount of twist that makes the angle of incidence lower at the tips than at the roots. The reason for washout is that we want the roots to stall before the tips. Our wings are supposed to have 2 degrees of washout. I measured a few tenths of a degree more washout on the left wing than on the right. This was "fixed" by lowering the right flap a bit.
There were something like 10-12 ES kits in some range kit # range that I don't have at my finger tips that had an even bigger difference in twist between the wings. Some of the builders of those planes used something called "eccentrics" to alter the relative incidence of the wings to eliminate the problem. I am not sure how they work, but there are Lancair ES folks out there that are familiar. (I have emails with posts on the old Yahoo ES list I could share, and perhaps some folks on this list also know.) Some builders went back to the factory and de-bonded then rebonded their wings to get the washouts equal and eliminate the eccentrics. I recall someone mentioning that that Tim Ong (he was at Lancair at the time) thought that was over-kill because the eccentrics largely eliminated the issue, maybe at the cost of a bit more drag, but some guys went back and re-bonded their wings anyway.
I am not an expert, but your right flap doensn't look any lower than mine, maybe less lower, though its hard to tell from the pics. However, it looks to me like you have more aileron trim in straight and level. You might want to consider lowering the right flap a bit more, though I suggest talking to the guys at Elite Pilot Services or some other knoweledgeable folks about this. Have you tried checking for a washout difference? If the difference is big enough, you might want to consider the eccentrics that others have used (maybe some still are using them, I dunno). I don't have more info, but JC (EPS) is on this list and might comment if he's aware of the issue, and like I said above, I could pass on relevant posts on the old Yahoo ES list, which discussed this issue at some length.