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General control line discussion => Open Forum => Topic started by: Bootlegger on September 26, 2016, 08:52:51 AM
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Sat I limited elevator ringmaster to 15-18 degrees of travel and was rewarded with a much better flying model, now I want to do the same on a Sig Skyray.
What are your thoughts and why?? Thanks... y1 #^ n~
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I don't believe in travel limits. In the real world, flippers can travel 45 degrees but the pilots have the finesse to know how much to use. It's handy to have a A LOT when you really need it.
If a plane over-controls, use a taller control horn or move the CG forward. Control limits result in hanging the plane on one line. Not good.
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If it's working for you go for it. I put travel limits on my wife's Yak9 so she doesn't do a wing over on take off. Of course there's not enough up to flare on landing but it's the lesser of two evils. On my full PA airplanes when I get the sensitivity adjusted the way I like it I have just enough control travel to over control just a little.
MM
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Sat I limited elevator ringmaster to 15-18 degrees of travel and was rewarded with a much better flying model, now I want to do the same on a Sig Skyray.
What are your thoughts and why?? Thanks... y1 #^ n~
You solved about half the problem that way. What you did was prevent the elevator from moving so far that the airplane stalls. That corrects the worst problem, but not the only problem.
Don't limit the elevator with physical stops. Slow the control rate down by making the elevator horn longer, the bellcrank pushrod hole closer to the pivot, and/or narrower handle spacing. That way, instead of hitting the stops with very little hand movement, you can control how far it moves, and still limit the overall travel - you can only move your hand so far.
I very much doubt that you will have the same issue with the Skyray. Even on the stock airplane, I used every bit of travel there is and it was still impossible to stall - with the 20FP. In fact, it can't be moved far enough. On the rebuilt (all balsa) version, if I ever build another one, I will shorten the tail slightly to get a bit more action. It would like With the Fox on the original balsa version, I did have to slow the controls a bit from where I first started, but not very much.
Brett
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I don't believe in travel limits. In the real world, flippers can travel 45 degrees but the pilots have the finesse to know how much to use. It's handy to have a A LOT when you really need it.
On the Ringmaster, A LOT just causes it to stall more. Having any more than necessary to stall the airplane is just wasted travel. In fact, that's how to determine how slow to make it. Slow the controls down bit by bit until you can't stall it with full hand movement, then back it off to the last setting. That way you can get it just to the edge of the stall, without easily going over.
Brett
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What Brett said, plus, to answer your original question, a Skyray that's doing the pattern probably has +/- 30 or 45 degrees of deflection. With that skinny elevator on that fat stab you don't have to be shy about giving it room to travel.
And no, you do not ever need to increase the elevator area on a Skyray, at least unless you do something extreme like add flaps -- it's that skinny because the airplane doesn't have flaps, and as-designed it works just dandy. In fact, I have a couple of 40-sized trainers that I've built, with scaled up Skyray aerodynamics. They've both pretty much flown off the board.
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You solved about half the problem that way. What you did was prevent the elevator from moving so far that the airplane stalls. That corrects the worst problem, but not the only problem.
Don't limit the elevator with physical stops. Slow the control rate down by making the elevator horn longer, the bellcrank pushrod hole closer to the pivot, and/or narrower handle spacing. That way, instead of hitting the stops with very little hand movement, you can control how far it moves, and still limit the overall travel - you can only move your hand so far.
I very much doubt that you will have the same issue with the Skyray. Even on the stock airplane, I used every bit of travel there is and it was still impossible to stall - with the 20FP. In fact, it can't be moved far enough. On the rebuilt (all balsa) version, if I ever build another one, I will shorten the tail slightly to get a bit more action. It would like With the Fox on the original balsa version, I did have to slow the controls a bit from where I first started, but not very much.
Brett
EXCELLENT explanation - good work, Brett.
Bob Z.