1. The basis used for estimating lift and drag coefficients is explained. A method of obtaining a photograph of a bird flying at known airspeed and rate of sink is described.
2. 96% of the speed measurements fall between 22 and 65 ft./sec., the average being 40 ft./sec.
3. A maximum lift coefficient of 1.8 can be achieved. Wing area is reduced with increasing speed.
4. The feet are used as airbrakes.
5. A comparison of the minimum drag coefficient (0.06) with the maximum estimated power output of the pectoral muscles leaves only a narrow margin of power available for climbing.
6. The performance diagram gives a minimum gliding angle of 1 in 8½, and a minimum sinking speed of just under 4 ft./sec.
7. The fulmar has apparently sacrificed the ability to soar dynamically over the sea in order to be able to fly slowly and thus utilize light upcurrents at cliff faces.
- Copyright © 1960 The Company of Biologists Ltd.