Page:Aerial Flight - Volume 2 - Aerodonetics - Frederick Lanchester - 1908.djvu/383

Rh to pivot on the wire support (the aluminium being bent to form a hinge), and the provision of a stop consisting of a short strip of brass soldered in position to limit the angular motion and at the same time to locate the blade longitudinally.

Energy of Propulsion.—The energy of propulsion stored in the two indiarubber skeins amounted in all to about 1,000 ft, lbs. (loading energy); the total number of propeller revolutions being 500, representing an average of one foot pound of energy per revolution. This requires to be multiplied by a coefficient to give the energy available at the propeller shaft; in all probability, after allowance also for the propeller efficiency, not more than 50 per cent, of the loading energy is usefully employed in propulsion. The total weight of rubber in the two skeins is recorded as .7lb., each skein being composed of six strands.

General Notes.—The aerodrome weighed with rubber complete 2½lbs.; the angle made between the flat face of the aerofoil and the tail-plane as first adjusted was 8 degrees, but there is a record to the effect that the angle was subsequently increased to twice this amount, i.e., 6 degrees. The author has no note as to which of these angles was employed when the flight recorded in § 14 was made.

The range of flight should theoretically amount to about 250 yards before the energy of the indiarubber is expended, and there would be probably another 50 or 60 yards covered while the aerodrome is coming to earth. Unfortunately, owing to obstacles, the full range of flight was never realised; the most satisfactory flight is that recorded, but here the machine finished its career prematurely in an elm tree, the propulsion energy being only about half expanded.

An attempt made to photograph the aerodrome in flight proved abortive.