Hi, I've been experimenting with flaperons on my smaller glow and electric planes. My question relates to their use to slow the plane down for landing in a small tree lined field. Was originally told by the LHS that I wouldn't see any difference for the smaller planes, but I've expereinced otherwise.

I understand that when both flaperons are up, they become spoilerons - adding drag, and when both are down they act as flaps- adding both drag and lift (by changing the camber).

My old futaba radio manual recommends setting up flaperons as air brakes i.e. spoilerons - up only. The reason seems to be that full length ailerons, when deployed downwards as flaps, tend to cause the plane to tip stall. This seems to be the common view on a few web sites I've visitied as well.

However, I find that when I use the flaperons as spoilerons, I also lose a lot of lift such that a lot of up elevator is required just to keep the plane level. However, with the flaperons down as much as 45 degrees, the plane is still relatively stable and has a MUCH lower stall speed and smoother glide path. It's still less stable than when the flaperons are level, so I only deploy them like this once I've set up a good approach path.

Is there anything wrong with setting up flaperons to travel downwards as if they were flaps? How should I best use my flaperons for this application? Are there any rules of thumb when it comes to setting up flaperons?

Thanks.

FLAPerons act as FLAPS.
Spoilerons act as SPOILERS.

Flaps increase lift and drag, which lowers landing speed and shortens landing length.
Spoilers decrease lift and add drag (but not as much drag as flaps). This allows VERY steep approaches.

Experiment with both, in varying amounts, and see what effect you like the best.

In competition Fun Fly we used spoilerons to kill the lift, literally sucking the plane back to touch the ground for fast event times. Flaperons were mixed with elevator (up elevator, down flaps), like the old control line planes, to generate VERY tight loops without the plane stalling out at the top.

Dr.1

Thanks Dr.1.

Was just concerned that I was doing something I shouldn't.

Flaperons are fine until you try to use the ailerons with larger flap angles. With the flaps down at around a 30 degree angle the ailerons will just barely still act like ailerons. A few degrees more flap and they become very ineffective. A few more degrees and they actually reverse their effect. This is due to the high drag of the down aileron side that creates a very strong adverse yaw.

So to maintain better control you're better off using spoilerons.

But play with both options and see what you like best.

Hi Bruce ... your explanation unravels the mystery for me. More or less experienced the effects, but I was wondering why.

Realise that different planes behave differently; my 1/2A corsair lands great with 30% flaperons down - just floats in so gently. but, with the flaperons fully down, it becomes highly unstable. In contrast, I have an electric tucano that is totally uncontrollable with the flaperons any more than about 10% down. Spoilerons, with lots of up elevator, work great though for slowing it down on a steep descent.