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tnToast
Columbia TN
Posted:July 20th, 2008
12.12 PM |
Re: airfoils. I like this article, I see common sense in it. A point to make: for fabric or film covered wings, the selected airfoil is "true" only at a rib(other than LE sheeting); every other location is "modified" by fabric sag between ribs. I have read elsewhere that this sag has a minimal effect.
My experience agrees with yours: compared to a true "flat bottom," a symmetrical (or semi-) airfoil is much smoother in pitch control and is much easier to fly. The "conventional wisdom" that a trainer MUST have a high wing and a flat-bottom airfoil is, in my opinion, an old wives' tale that is short on fact. |
george
Vancouver
Posted:March 28th, 2006
12.07 AM |
It is interesting to read your comments regarding airfoils. I was struck most by your statement regarding flat-bottom airfoils. Whereas for r/c models, this airfoil may be impossible to trim, for free flight hand launch gliders, it is the standard by which most of the experts have sworn since the mid-1900's. An undercambered wing can be, and has been used in ffhlg, but mainly for indoor gliders, where drag concerns are minimized in situations where limited launch height is the norm. Outdoor gliders are somewhat compromised by the use of an undercambered wing, where launch altitude is paramount. I have made a couple of undercambered wings, and the still air performance in terms of lift is definitely superior to the flat bottom airfoil. In conditions of wind, however, much altitude is lost in the launch phase. I have an r/c glider, but am not much interested in it. I choose instead to marvel at a glider free from control, at the mercy of the elements, dependent for its performance on the quality of one's buidling and trimming skills. The ultimate thrill for me is see a glider one has built sailing away into the distance like a migrating bird (not, of course, during a competition).
Cheers
George Clarke |
dmccoach
Kutztown, PA
Posted:January 9th, 2005
7.02 PM |
I would like more information on usage of families of airfoils... i.e. I have Profili, but how can I find out the characteristic difference between, say a GOE459 and the Jukowski airfoil and how might they compare in expected benefit or to the NACA series, etc. Any input on this? |
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