I built this wing for my Wing Dragon specifically to explore the effect of flaps and the result on the handling as the basic 4ch Wing Dragon is considered pretty forgiving.
The 40" wing is tapered 2:1 has a constant Clark Y section and with no washout.
Although quite a good shape structurally such a configuration might be expected to demonstrate quite 'aggressive' characteristics with the tip stalling first.
The flaps are quite generous covering 2/3 of the trailing edge, are fully variable and can descend to a high drag 70 degrees.
Compared to current fashion the ailerons are quite small but do have a differential action (more up than down) and are completely independent of the flaps.
The basic questions were:
1. Do the flaps work and how slowly can it fly.
2. What happens as they are deployed.
3. What are the stall characteristics and is adequate aileron control maintained at the minimum speed.
This video shows their effect.
Although not intended to be aerobatic it nevertheless has quite a spirited performance and the flaps certainly work allowing it to fly well below the 'clean' stall speed.
It is interesting to note that with full flap the angle of attack is hardly altered. This means the airflow at the wing tip is not
stalled and thus the ailerons remain effective, albeit with decreasing effectiveness as the speed reduces. Their differential action seems to keep the adverse yaw in check when full aileron is applied at slow speed.
The only drawback is a substantial nose up pitch when the flaps are deployed at normal flying speed, however if the speed is reduced in conjunction with the flaps the final trim change required is no more than a few 'clicks'.
So far so good!