screamn1

I got an AMD sailplane from someone on Ebay. It is Hong Kong based and is of very high quality and craftmanship. The instructions were a one page type with very little details but......
It has an 80" span with a fiberglass body and a 600 spped motor system. I flew it for the first time yesterday and it had very little left turn even with 1.5" of throw in the rudder but it had tons of right turn. After the club looked over the glider it has lots more washout on the right wing panel than the left had. We assume that is why we had very little left turn. I've twisted the left panel down to match the right panel. When the wing panels are laying flat, both sides have about 7/16 of tailing edge washout. Is this too much? I'm just not sure how much washout should be in the wings if any.
Thanks for any comments.
Palmer

theox

General consensus seems to indicate about 2 degrees.

http://www.rcuniverse.com/showthread...550&forumid=19

http://www.rcuniverse.com/showthread...235&forumid=34]

Johng

My Feedback: (4)

About the rudder pushrod - is the control horn mounted on the right side of the rudder?

If so, it could be that some part of the pushrod is bucklilng when in compression - so you don't get the rudder action you think. When the pushrod is in tension - it won't buckle and you get much more rudder on that side.

Check by deflecting the rudder with the servo, then push back with your hand. See if the rudder holds stiff, or can be pushed back easily.

screamn1

Well the pushrod was also my concern so I installed solid wire rods for both rudder and elevator. There is now no way that there is any slack. The kit came with a cable system but I wasn't impressed so that is why I replaced them. Yesterday we did some low passes and we could see that the rudder was going all the way to the left so that wasn't the issue..... but thanks for suggesting it.

Jack Hyde

My Feedback: (1)

Washout makes the angle of attack of the tip less than the root so the root section stalls first - no tip stall. Optimum design is to use just enough washout to force the root to stall first. More washout makes the tip section fly at less angle of attack so produce less lift. It is safer to have too much washout, faster to have less. How much washout is enough depends on the airfoils and wing taper distribution. A wing with a constant airfoil and lots of taper will tip stall unless washout is used. You have close to 5 deg washout which is more than usual. It won't make the plane not turn if both wings are the same. If you have 5deg washout on one wing and zero on the other it going to cause the wing with more washout to rise , bank the plane and turn the plane away from the twisted wing. The rudder has to fight the twist effect and turning is not so good.
Your plane should turn fine with both wings twisted the same. After a few flying sessions I would try using about 1/3 less washout to get a little better performance.

screamn1

Jack,
Thank you so much for your reply. I flew the glider today and it had a lot more left turn than it did the other day. I will do as you have suggested and reduce the amount of washout to help the performance. The wing is 80" long with a flat bottom and has a 8.5 width at the body and the tip has a 7.0 width at the tip which would be 40" away so there isn't too much taper.
Once again.... thanks for your reply.
Palmer

rogerflies

My Feedback: (3)

Sorry, Jack, but you mixed it up. The plane will turn toward the wing with more washout, since the other wing has more lift. The other info was right on.

Roger

The divided drum give you optimum winch performance and consistent "feel", regardless of the distance to the turnaround.

Jack Hyde

My Feedback: (1)

Yeah I got it mixed up. The washout acts like one aileron going up, pushes the wing down, ergo turn is toward the washed out wing if only one wing has washout. Its good someone is awake.