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General control line discussion => Open Forum => Topic started by: Paul Taylor on July 05, 2010, 08:43:26 PM
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Need a little input.
Was flying my Akrobat today and it seems like it is going to be a good flyer. I was just flying and doing insides and outsides getting a feel for the plane. I hope I am explaining this right. When the plane comes around on the down side of the outside loop it seem to get a little light on the lines. I had my flying buddy look at the flaps and checked the wing, tail to see if anything needing tweaking. Could not see anything, so I thought I would ask here if anyone might have some ideas.
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What was the wind like at your field today?
Sometimes a *little bit* more rudder offset can help here, but be careful as too much rudder creates problems elsewhere.
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Paul,
I've got a few questions. First, what is the configuration of the airplane? Flapped or not? Profile/full fuse? Wing area and span? Line length and approximate lap times? Power train (engine, prop, fuel)? Was it windy? Do you know about "biasing" loops into the wind? Is the outboard wing higher than the inboard in level flight? If you balance the airplane by your index fingers on each wingtip, how far behind the inboard finger tip is the midpoint of the leadouts?
If you're getting the idea that what you've asked isn't a simple question, you're exactly right!
Ted Fancher
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What was the wind like at your field today?
Sometimes a *little bit* more rudder offset can help here, but be careful as too much rudder creates problems elsewhere.
NO NO NO NO NO......rudder offset does not help - it hinders more than anything......dont add rudder offset!!!
Paul - when you are flying your loops - look to see if you can see the top of the outboard wing during insides - if you can - add more tip weight. if you can't - fly outsides - and watch to see if you can see the bottom of the outboard wing - if you can - remove some tipweight......the idea is to not be able to see either of them when you are flying through loops.......
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Hi Wynn,
(snip)fly outsides - and watch to see if you can see the bottom of the outboard wing - if you can - remove some tipweight.
That's confusing to me in a way. But I think I know what you mean. ;D
By *bottom* are you actually meaning the "top" of the outboard wing when it is sitting on the ground (because that would be the *bottom* when inverted.) ?? I am thinking the *outboard* wing is higher if you are seeing *bottom* of the model's "outboard wing". That would indicate not enough wing tip weight.
In other words, if the outboard wing is high in both directions= not enough wing tip weight.
If the outboard wing is "low', in both directions= too much wing tip weight.
If the outboard wing is high one direction, low the other= warp/misalignment.
Just a general method.
Make sense?
Thanks!
Bill
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Had the same problem with a couple of Twisters...tried everything I was told to do from forums...finally tried a Rabe rudder hookup...it fixed the problem and also let me use less initial rudder offset. I don't fly Twisters any more but is sure worked on them.
Phil
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I'd say stick a penny to the right wingtip[with tape] and try it again.....no sweat. H^^
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Need a little input.
Was flying my Akrobat today and it seems like it is going to be a good flyer. I was just flying and doing insides and outsides getting a feel for the plane. I hope I am explaining this right. When the plane comes around on the down side of the outside loop it seem to get a little light on the lines. I had my flying buddy look at the flaps and checked the wing, tail to see if anything needing tweaking. Could not see anything, so I thought I would ask here if anyone might have some ideas.
Paul –
Since you did a visual alignment check and didn’t see anything, this probably isn’t it. However, a high inboard stab tip can cause the problem you describe.
Here’s the deal. A high inboard stab tip, given some down elevator, will cause the empennage lift vector to point the nose towards the center of the circle. Unfortunately, the GP forces are also pushing the nose inboard at the same time, a bad combination.
In effect, a high inboard stab tip works like a “Rabe Rudder” hooked up backwards. :(
That is different than saying a low inboard stab tip works like a Rabe Rudder. Stab tilt in the other direction would act like a Rabe Rudder with a maladjusted linkage that gave left rudder on insides.
Larry Fulwider
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Lots of great info here guys. When I get home next week I will give it the once over again. My flying buddy said there might be just a slight twist in the outboard wing, but it is not real obvious. I will try and tweak the wing and reheat the monokote to see if that makes a difference.
For more info.
The wind was a little gusty but not real bad.
Plane is a Sig Akrobat full fuse stunter. LA .46 engine, TT 11.5x4 prop. CG is on the spar. Launch RPM was 9700.
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NO NO NO NO NO......rudder offset does not help - it hinders more than anything......dont add rudder offset!!!
Hmmm....... gee, helped when I had the same problem. Must have been my imagination. ::)