Banshee flap advice

I have been digging thru the archives for days and discovering so much. One article Leonard described the complications that could be caused by a fuselage offset on the wing. Flaps being of different sizes creating a roll effect with adverse yaw and other problems. My banshee built with the wing offset per plans, shows some of these problems. The right(short) flap is further reduced in size to allow for elevator pushrod clearance. I am wondering if removing about an inch from the inboard of the left flap might equal things out a bit?

Some designs call for flaps that are less than full span to begin with, so it would be possible to simply shorten the inboard flap and fix the remainder stationary. You could also add a "wart" (tab) to the outboard flap at the tip. One question that might help you determine which way is best to go would be to check for the quality of turn that you get under the present set up. Does the tail rotate in a turn, or does the wing want to climb? If the wing is climbing, you probably have too much flap and then shortening the inboard flap would help. If you do not have adequate flap (plane too heavy) then adding the wart would be better.

>
>I have been digging thru the archives for days and
>discovering so much. One article Leonard described the
>complications that could be caused by a fuselage offset on
>the wing. Flaps being of different sizes creating a roll
>effect with adverse yaw and other problems. My banshee built
>with the wing offset per plans, shows some of these
>problems. The right(short) flap is further reduced in size
>to allow for elevator pushrod clearance. I am wondering if
>removing about an inch from the inboard of the left flap
>might equal things out a bit?
>

Well, maybe. Assuming you have gone through the usual leadout/rudder/tipweight machinations without being able to fix it, then maybe a tab on the outboard flap may fix it. However, I would exhaust all other possibilities first - and I presume that you have sealed the hinge lines. There's nothing really wrong with assymetry, and I would wager than 95% of all stunt planes ever built since the early 50's have had some.

I'm reasonably confident that the cutout around the pushrod is not a significant effect - it's only 3/4" or so from the lateral CG and thus is very unlikely to create much torque.

I have installed adjustable leadouts, some help but still testing the for the best position, plane really likes to fly inboard wing forward. Have removed engine offset. Next will be to straighten fin. Did the inverted flight test and found slight flap difference, corrected by twisting flap connecting rod, flies level both ways now. Have a weight box but haven't installed it yet, to me tip weight doesn't seem to be a problem, good line pull everywhere. In hard loops in or out there is roll and yaw, just doesn't track good, my son's twister tracks much better.
I have another banshee kit and would like get my skill at flying and trimming better before I start the new kit. OOORRR should I sell it and put my efforts into a more modern plane.

The Banshee, although not being my first choice, can be a good flying plane. It does have too much assymetry, however. Of those modelers using assymetry today (and there is debate on the issue) most flying modern designs will not use more than half to three quarters of an inch. That, in and of itself, will take care of the difference in air speed between inboard and outboard wings flying in a circle. However, it also means flying with much less tip weight, when aiming the plane up, becomes less than desireable since the effects of assymetry no longer apply. Tip weight, when used alone, works in all attitudes of the flight pattern (well, that is my argument, anyway.)

If you measure the assymetry of the Banshee, you will find that you have more, with a slightly smaller wing. Now, if you have added tip weight as well, you will have the banging in the corner that you are experiencing. To counter this, you can take the tip weight out (less tension) or increase the outboard flap or decrease the inboard flap. I don't believe you can get a perfect flying plane without doing one of the latter, although you can get close (albeit with less tension) by proper trim including removal of tip weight.

If you had too much offset, you have already addressed one problem. Straighten out the rudder, decrease tip weight, and then work on the rest of the trim. When all else fails, adding a wart to the outboard tip of the flap is the easy way to go. And "just to see", take a couple of pieces of 1/16 balsa about 1 1/2 inches by 4 inches and use silicone sealer to attach one on top and one on the bottom of the flap with about a half inch hanging behind. This is easily removed again after your experiment but it will give you a feel of the effects of added outboard flap area.

Thanks for the ideas, I guessed that all of these corrections might be necessary, now I know where to start. I've read about banging in corners, so this is it. The plan called for a hefty weight in outboard wing tip. Well the weight box shouldn't be too hard to install in my monokote wing, and hopefully the epoxy won't be too tough on the rudder. Maybe I'll have some improvement by this afternoon.

I removed the oz. of weight in the tip and installed the weight box with a half oz. Then cut off rudder and reinstalled with just slightest offset. One quick flight and it was tracking muuucchh better and no yaw thru loops. It still flies a little inside wing foward and as it comes out of loops the inside wing takes a quick drop, right where it started the loop. It recovers instantly. I guess next I will play with leadouts.
Thanks