[homme de fer]

Morning all,

Last night, I was putting the finishing touches on the right wing of my Dynaflite Super Decathlon. I built it slow to make sure I had the correct washout but somewhere along the line, I somehow managed to built it with only 1 degree of washout rather than the 2 degrees required.

I did some research and responses seem to be this:
1 - Do nothing and just set the aeleron to 1/8" up on the right wing when landing

2 - Wet the sheeting on top of the wing, twist it to 3 degrees of washout and let it dry over night

3 - Cut slits in the last 4 bays of the wing, twist it to 3 degrees of washout, and reglue the slits with wood glue. Allow it to sit over night.

Has anyone experienced this on their plane, and, if so, what method did you use to induce the correct washout.

Thanks for your help,

Marc

P.S. Option 1 is by far the easiest but I would rather get it right without the need for trimming.

[volksman]

if both wings are equal what is the big deal only thing a bit more speed may be needed or it will drop a wing. the pilot is in control if its not real far out of whack everything will be fine

[Mike Sebastien]

The reason a designer incorporates washout into a wing is to let it stall evenly along the entire wing. In a ideal world you would want the wing to stall at the root first and then at the tip. My guess is you have a semi symetrical airfoil and 1 degree of wash out will be fine. Doing any of your 3 options may just make things worse. Leave it alone and enjoy the airplane.

[homme de fer]

Originally Posted by Mike Sebastien

The reason a designer incorporates washout into a wing is to let it stall evenly along the entire wing. In a ideal world you would want the wing to stall at the root first and then at the tip. My guess is you have a semi symetrical airfoil and 1 degree of wash out will be fine. Doing any of your 3 options may just make things worse. Leave it alone and enjoy the airplane.

You are correct Mike, this is a semi symetrical wing. I am more bothered by the fact that I was really careful about building the washout and still didn't get it perfect.

[kip51035]

I take it that you have 1 deg in one wing and two in the other! I us heat, it works best on a doped wing, a non covered wing I support the trailing edge with a couple of yard sticks. Tie the wing down with more than twice the correction you need and apply heat, a couple of hair driers, I have even held it over the stove. If there is a lot of sheeting on the wing get it good and wet with a sponge. Apply enough heat until the entire structure is hot. It helps if you cover the wing to keep the heat in. If the L/E is a box spar assy you will have to wet it so the wood will give, Caution too much water will cause some glues to separate. Trimming the aileron will only have the right effect within a very small speed range. If you are really lucky the entire wing will twist. Quite often you will introduce a new lateral twist that changes the shape of the airfoil. Try an initial twist to see where the wing gives and where it does not, so you will know where to apply the wet sponge. If you used water leave the wing in the jig over night in a warm environment, if not leave it an hour or so until it cools. When you take it out of the jig give it a couple of medium twists both ways to see where it is going to end up. Check it the next day to see if what you have done has taken, some times only part of the adjustment remains. Good Luck

Kip

[moo]

Wood is like that.

[homme de fer]

Originally Posted by kip51035

I take it that you have 1 deg in one wing and two in the other! I us heat, it works best on a doped wing, a non covered wing I support the trailing edge with a couple of yard sticks. Tie the wing down with more than twice the correction you need and apply heat, a couple of hair driers, I have even held it over the stove. If there is a lot of sheeting on the wing get it good and wet with a sponge. Apply enough heat until the entire structure is hot. It helps if you cover the wing to keep the heat in. If the L/E is a box spar assy you will have to wet it so the wood will give, Caution too much water will cause some glues to separate. Trimming the aileron will only have the right effect within a very small speed range. If you are really lucky the entire wing will twist. Quite often you will introduce a new lateral twist that changes the shape of the airfoil. Try an initial twist to see where the wing gives and where it does not, so you will know where to apply the wet sponge. If you used water leave the wing in the jig over night in a warm environment, if not leave it an hour or so until it cools. When you take it out of the jig give it a couple of medium twists both ways to see where it is going to end up. Check it the next day to see if what you have done has taken, some times only part of the adjustment remains. Good Luck

Kip

Actually, I haven't started the left wing yet. I was hoping to iron out the bugs with the right wing first.

So that I understand your directions, I would wet the sheeting of the top of the wing, induce a twist, weigh it down, then hit it with heat. Is that right? My only concern would be that I might impart a bow in the wing.

Leaving it alone is looking like the best option.

[Terry Gauvin]

Originally Posted by homme de fer

Actually, I haven't started the left wing yet. I was hoping to iron out the bugs with the right wing first.

So that I understand your directions, I would wet the sheeting of the top of the wing, induce a twist, weigh it down, then hit it with heat. Is that right? My only concern would be that I might impart a bow in the wing.

Leaving it alone is looking like the best option.

I certainly wouldn't do anything until I built the second wing. 1 degree of washout rather than 2 will be of little consequence to you, the most important thing is that you have some washout and you do. The next thing to focus on is getting both wings the same, spend your time on the second wing and see what you end up with before even considering attempting to mess with the first one. If you end up with 1 degree on both wings then cover them and go fly.

[Mike Sebastien]

Originally Posted by homme de fer

You are correct Mike, this is a semi symetrical wing. I am more bothered by the fact that I was really careful about building the washout and still didn't get it perfect.

You may not have done anything wrong, sometimes designs are changed and the plans aren't amended.

Like Terry said, make sure both wings are the same, cover them and go fly.

[VERTOL]

If the wing is covered w/ iron on covering (monocote etc.) this is what I do using hot air
(hot air gun).

Sitting on a chair (or high chair if the wing is one piece),
hold the wing between your legs and w/ one hand gently twist the wing tip to the
desired direction of twist....wrinkles will form on both sides (top/bottom)
of the wing... with the other hand holding the heat gun...blow the wrinkles off
until they disappear.

Do this on both ends of the wing (left/ right).

Keep checking and twisting until you are satisfied. If too much go the other way.

This is also a good way to correct wing warps.

I hope this helps.

Dom