General control line discussion > Open Forum
Odd Airfoil
Ken Culbertson:
I found this airfoil on a three view of one of the European F2B planes but I cannot remember where I saw it. I built a stab using it for Endgame IV but it is not too late since I have not mounted it yet. I used something similar on Endgame III with a much thicker elevator LE and it flies great. It appears to be designed for corners with a significant dead zone around neutral. I do not grasp the significance of the rounded stab TE leading into the flap recess. The one I built is flatter at that point. Has anybody seen this before? I am very open to suggestions.
Ken
Air Ministry .:
Think its pretty much the same theory as ' taped hinges ' . A ten foot gap ( as it were ) and the air bleeds through . PRESSURE .
wereas ' sealed ' it acts ' of a piece ' , rather than two joined /
Think it was a Dutch bloke , picture of ' hinge ' in Aeromodeler Mag. with paper or cloth in the gap , to illustrate the closeness off fit .
So , seeing the picture , every man & his dog tried it . a few Germans & Italians anyway .
Other Thing is the surface continuity , when the elevators deflected . The hope is that the air stays glued on .
Traditional ' sewn ' hinges , with radius , the elevator ' rolls ' on the stab. Similar effect . But impossable to calculate true center of deflection, perhaps .
Ken Culbertson:
A little more investigating and I remember where I saw it. It is a imbedded version of Igor's MaxBee. Still want to know something about it.
Ken
Brett Buck:
--- Quote from: Ken Culbertson on April 16, 2024, 11:13:12 PM ---A little more investigating and I remember where I saw it. It is a imbedded version of Igor's MaxBee. Still want to know something about it.
Ken
--- End quote ---
I am not sure what the question about it might be. If you took a solid airfoil, and decided to hinge it at the 40% mark, that's about what you would wind up with. It's a common full-scale practice, and most of the similar attempts at model implementations look about the same. If you later decide to make the elevator smaller than the stab, you have what you show.
It doesn't prevent air flow through the gap like a seal. But it does greatly reduce the discontinuity you would otherwise have with a right-angle trailing edge and a wedge on the LE, which is a huge divot even when not deflected and a massive divot when it is deflected.
Brett
Ken Culbertson:
--- Quote from: Brett Buck on April 16, 2024, 11:21:58 PM --- I am not sure what the question about it might be. If you took a solid airfoil, and decided to hinge it at the 40% mark, that's about what you would wind up with. It's a common full-scale practice, and most of the similar attempts at model implementations look about the same. If you later decide to make the elevator smaller than the stab, you have what you show.
It doesn't prevent air flow through the gap like a seal. But it does greatly reduce the discontinuity you would otherwise have with a right-angle trailing edge and a wedge on the LE, which is a huge divot even when not deflected and a massive divot when it is deflected.
Brett
--- End quote ---
Thank you. The only difference would be imbedding the elevator 1/8" into the stab. I have been doing that for years on my stabs without sealing them. When I watch Matt's WC plane corner effortlessly, I wonder if it is worth the effort when you can achieve nearly the same results with conventional construction. Probably not but it is a hobby after all.
ken
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