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Old 01-13-2014, 01:57 PM   #1
drummaker
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Default Flaperon Epiphany

I had an epiphany I wanted to share.

I have come to some conclusions so. let me know if you KNOW if I am wrong, but I have been studying fluid dynamics, and I believe strongly that I am right here. I believe this info to be invaluable to many people

Have you even noticed that so many ailerons which cover the full length of the wing are wider at the inside than they are on the outside? They are this way for a great reason, and if you are scratch building, or contemplating flaperons or spoilerons you should be aware of why, and what.

When you are moving the trailing edge of a wing down you are actually doing 3 things.
1. Adding Camber. Camber is a description of an airfoil that his concave on the bottom, and is known for a LOT of LIFT per Square inch of wing. so you are adding lift to the wing, thus adding the ability reduce your minimum stall spead.
2. Cambered wings add drag, so the model slows down.
3. This is the important part for Spoilerons V Flaperons.
When you lower the trailing edge of the wing, you are also changing the incidence, or angle of attack of the wing. This is important because of several things, and is the reason you must add down elevator to compensate, but mainly when you have a straight non beveled aileron, you are changing the incidence of the whole wing, and therefore when you slow down enough, if there is no wash out in the wing, you will tip because the entire wing looses lift at the same time. OK now pay attention. When you have an aileron tapered wide toward the fuselage and narrow toward the tip.. YOU ARE ADDING washout by lowering the ailerons. This is because you are adding more incidence on the inside than outside of the wing because the aileron has more actual down deflection here.

It follows that if you move the ailerons up, you are actually adding Wash In which causes tipping again but usually pushes the model down so fast it doesn't matter.

Using Real flaps works so well because it causes washout ..


There are some smart people out there aren"t there? Every time I figure something like this out it gives me renewed respect for those who came before us. It took me a lot of pondering to figure out why full length ailerons were so often shaped that way.

Hope this helps!
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