I've just built a 4 star 40 wing and inadvertenly ended up with approximately 1 degree of twist. The wing isn't yet covered. I'm about to cover the wing and have an incidence meter in my toolbox. Most people with whom I've discussed the problem suggest that I should cover the wing normally - then twist it slightly more than one degree, and iron out the resultant wrinkles. I'm wondering if anybody has any different ideas or experience. Thanks in advance. .. Ken

1 deg of twist is almost ignoreable on the 4*40... Its also possibly within the margin for error of installing the incidence meter.

You can steam the wing and twist it straight:
Hold over pot of boiling water for 10 to 30 sec, twist opposite the warp, slightly more than just back to straight, pull from steam and hold for 1 min. recheck for straightness.

You may find that as you iron the covering on, the wing relaxes the steamed correction, and goes right back the way it was.... That's why we normally correct durring covering. Get the covering on, check for warps, twist past correct, heat the covering and remove wrinkles, let loose and let cool. Recheck. (just as you were advised before...)

Good response, fhhuber .. thanx! If the incidence at the tips was less than at the root, I'd be more inclined to leave it alone, but the way it is with the incidence greater at the tip than the root, it's more likely to invite nasty behavior. Re twisting once the wing is covered:- would you be inclined to A) cover the wing - then, tighten it up with the air gun - then take the twist out, or B) cover the wing - then take the twist out - then tighten everything up with the heat gun. .. Ken

I tighten, then twist out any warps found and re-tighten. Some people will block a wing in place as they do the initial shrinking, to prevent introducing a warp. (I've never had a problem with that...)

the covering should be able to fix it

I am also in the process of building a 4* 40 and when I began the sanding step, I noticed that my left wing panel was also warped. However it is warped in both directions. The biggest problem is from left to right. Once it is placed on a flat surface the end curves upward and it also has a small twist. The deflection is about 1 cm from left to right. The right wing panel is OK.

I am about to cover the wing and I am wondering what the best solution is to remove the curve and twist.

Its a bit harder to remove a dual direction warp... But the techniques are pretty much the same.

Steam just the inboard section, and correct that half of the wing, then do the outboard section. Get it as good as you can... cover and then you have to again make the corrections inboard, then outboard. (becuase part of the warp will return durring covering.)

With one part of the wing warped one way, and the other part another... it gets quite hard to get it trued up. fortunately, the 4*40 is a plane that will fly fairly well with a significant warp in the wing. If you can't completely correct it, you can fly it. The bad parts of flying with a warp: The changing trims for different airspeeds. (extreme warps can make it impossible to trim out within the range of the TX trim levers If its that bad at any speed, you must try to further reduce the warp.) You also will have a tendancy to always fall off on one wing when it stalls.

As there is no planking on the wings, the steam wont do much as ironing cover will warp again.

Just go as everybody a you'll be ok. By the way, always doubt a little the incidence meters. Use your sight to be sure no warps in a non incidence plane have been made. e.g., awing with a curved diahedral that the incidence meter cant detect

good luck