Slight twist in LH aileron

Gregg Brightwell · #1 01-16-2012, 06:12 PM

Hello all, haven't posted in a while. I just finished building my left hand aileron. Alas, I am not sure if the skin wasn't trimmed perfect square, or if I just plain ole' goofed. The aileron is completed, and when set on a true-flat table, the inboard end of the trailing edge touches the table, and the outboard end is 3/16ths to a 1/4" off of the table. So, just less than a quarter inch of twist over better than a 4' span. I don't like it, but I don't know how much twist, if any, is 'ok'. Ideas?

Thanks,

Gregg

jthocker · #2 01-16-2012, 07:03 PM

Gregg,
It will fly just fine with that twist. Build on!

jsharkey · #3 01-16-2012, 07:30 PM

My RV-6 has a similar twist in one aileron that I worried about all through the rest of the build. I think it sneaks - and locks - in when you rivet the wobbly end ribs to the steel nose pipe/counter balance - and everything else follows from that.

In practice though the plane flies beautifully "hands and feet off" with no "heavy wing". I did put a lot of time and effort into accurately rigging the empenage and wings to the fuselage though. Errors here probably have more effect on trim.

Jim Sharkey

WAM120RV · #4 01-17-2012, 02:32 AM

Hi

I am not disputing what the guys say above, but when I clecoed mine together on the 4 I also found a twist.

I measured things up and found the bend had been put in out of square..... Vans sent me out some new skins bent correctly so now I have straight ailerons.

Obviously you can take the advice above or contact Vans.

Best

Derek · #5 01-17-2012, 03:00 AM

Greg,

The only down side I see ( very minor ) is that the twist may be noticible when installed on the wing i.e if the outboard end of the aileron is lined up nicely with the wing tip the inboard edge may not line up with the flap. Like others have said, more a cosmetic issue than anything else. Ive just finished my ailerons and they are the same as yours ( 3/16" twist ), for me if the twist is noticable ( if it bugs me ) when installed on the wing, I may do something to rectify.

terrykohler · #6 01-17-2012, 03:38 AM

With just a little squeeze of the trailing edge...
If just a slightly sharper bend can change the balance, it sounds like proceeding with a bent control surface is begging for an offsetting fix somewhere else. Do-able? Probably. But the best solution for a bent rim on your car isn't necessarily to start bending another. I twisted one of my ailerons during build. Bruce at Vans encouraged me to build another. Just remember, any advice On the forum (mine included), is free and should be treated accordingly.
Terry, CFI
RV9A N323TP

az_gila · #7 01-17-2012, 08:39 AM

Quote:

Originally Posted by Derek

Greg,

The only down side I see ( very minor ) is that the twist may be noticible when installed on the wing i.e if the outboard end of the aileron is lined up nicely with the wing tip the inboard edge may not line up with the flap. Like others have said, more a cosmetic issue than anything else. Ive just finished my ailerons and they are the same as yours ( 3/16" twist ), for me if the twist is noticable ( if it bugs me ) when installed on the wing, I may do something to rectify.

Depends on the direction of the twist...

On most of the old style (-4 and -6) wing tips, the tip TE is about 3/16 out of alignment (tip molding high) anyway.

You may have just cancelled the error out....

Andy Hill · #8 01-17-2012, 10:44 AM

The challenge is to now build the other aileron with the opposite twist

Gregg Brightwell · #9 01-17-2012, 12:29 PM

Perhaps a silly question, but can you tell if the bend is incorrect BEFORE building the aileron? I am about to start the RH aileron now. It would seem at first glance that you could measure both ends from the leading edge (spar attach that is) to the radius of the bend. However, only 3/16th's out over 54"....? Looks like a couple thousanths could do that. If I COULD get a measurable difference, would Van's just send me a new skin based on that?

I followed the instructions on building the aileron.... I used weights, and made a conscious effort to NOT have any twist. I'd hate to build the other aileron and have the same result. The one thing that came to mind... I wonder, if there could have been any torsion load at all on the pipe counterweight when I riveted it to the nose ribs. That could induce a slight twist, I reckon...

At the end of the day, I do high quality work. I want to build these parts as good as I can build them. I'd just hate to 'do it right' and still get the twist.

jsharkey · #10 01-17-2012, 05:18 PM

Quote:

Originally Posted by Gregg Brightwell

Perhaps a silly question, but can you tell if the bend is incorrect BEFORE building the aileron? I am about to start the RH aileron now. It would seem at first glance that you could measure both ends from the leading edge (spar attach that is) to the radius of the bend. However, only 3/16th's out over 54"....? Looks like a couple thousanths could do that. If I COULD get a measurable difference, would Van's just send me a new skin based on that?

I followed the instructions on building the aileron.... I used weights, and made a conscious effort to NOT have any twist. I'd hate to build the other aileron and have the same result. The one thing that came to mind... I wonder, if there could have been any torsion load at all on the pipe counterweight when I riveted it to the nose ribs. That could induce a slight twist, I reckon...

At the end of the day, I do high quality work. I want to build these parts as good as I can build them. I'd just hate to 'do it right' and still get the twist.

Make sure that you do all of the "drilling" and "fitting" - including of the nose pipe - with the ribs and top or bottom skin on a flat surface and you'll be fine.

Jim Sharkey