Flight of a samara, Alsomitra macrocarpa

The steady gliding flight of samples of Alsomitra macrocarpa samara was filmed and analysed. By using the observed data, the flight performance of the samara was made clear. The lift-to-drag ratio or the gliding ratio was about 3 ∼ 4 and the rate of descent was 0·3 ∼ 0·7 m/sec, which was smaller than those of other rotary seeds. The flight was so stable that samples were seen to take their optimal trimmed angle of attack with a value between the maximum gliding ratio and the minimum rate of descent. The aerodynamic function of the husk for the distribution of the seeds was also revealed by making wind tunnel tests of the husk.