Mechanics

A human-powered plane provides some special challenges in stability and control. As shown in the photograph of the Gossamer Albatross, the plane is flown close to the ground at relatively low speed, has a large wing-span and a canard stabilizer (front lifting surface) with about 12 % of the wing area. In sustained flight, the available power is low and drag must be kept to a minimum. Significant experimental input was required to develop the controls for this plane.

The canard is hung from the boom and has two flexible tabs that act as ailerons, banking the complete canard about its hanging bar. This alters the direction of the lift vector, and the banked canard pulls the aircraft nose in the direction of the desired turn.

From: Burke, "The Gossamer Condor and Albatross," Report No. AV-R-80/540, AeroVironment (1980)

The outer ends of the tapered wing can be twisted by about 2⁰ to aid in the turn. The downward twist of the trailing edge increases the drag of the wing tip on the inside of the turn and slows this wing to give the correct yaw moment to establish the turn (rather than the opposite yaw expected from the increased angle of attack). The changed flow over this wing reduces the pressure differential across the tip by about a factor of two. The combination of canard and wing behavior gave a well coordinated (low sideslip) turn in the desired direction.