A Question from Ed Boehm:



Gentlemen, any communication to your page re the Lazy Bee aileron version having relatively ineffective aileron response? [...] At this point, even though I am happy flying with coupled rudder/aileron, I am trying to understand the aerodynamic reason why Bee ailerons don't like to roll the Bee...with such large "barn-door" area I would expect those ailerons to be much more active. Any light you might shed on this issue would be appreciated.

Fellow Bee Flier, Ed Boehm




Answers from Tim Meyer-König:

Because the fuselage of the Bee is so high, and all the heavy components are mounted far beneath the wing, the centre of gravity of the fuselage lies very low. But on the other hand, the wingspan is very small, so the leaver of the ailerons is small too. That could be the reason, why the aelerons have such a poor effect and because they are so big, the adverse yaw is so big.
Try to hang up your Bee at the centre of lift of the wing and see, how much force you need, to lift up one wing then! Because of the short wing and fuselage, the inertia (right word?) around the vertical axis is extremely small, so that is why the rudder works so great!
Take the SpeedyBee: There, the wing lies much lower, so the force, the aelerons have to create, is less.

I think, that the problem described above is one of the reasons, but there is another, and so, together they result in such a bad behaviour of your Bee. Because the aelerons are so big, and the inertia around the vertical axis is so small, you will always have a big problem with the advers yaw. But because of the upward pointed wingtips, you get another problem. Take a look at the drawing for it! I have just looked at one aeleron wich causes a force downward. Because of the upward bending of the wingtips, the lever of the rudderforce is reduced, as can be seen. Because of the upward wingtips, the center of lift is also lying higher, which reduces the lever even more.
As you can see on pictures of the SpeedyBee, it has no upward pointing wingtips. So maybe that is why the aelerons of the SpeedyBee work so good.

I think, that the two mentioned points are the reasons for the bad working aelerons. Maybe you should try a bigger wing (if you really need them) or no upward pointing wingtips. But then it wouldn't be a real Bee, would it!?