Helicopter Design: Some Elementary Considerations on Efficiency and Control

REPORTS from America speak of flight tests of two types of screw‐lift aircraft, the Sikorsky multi‐rotor machine, and a twin‐rotor type. From this it would seem that the day of the practical helicopter, so Ions foreshadowed, is not far distant. The following general notes on design considerations may therefore be sufficiently topical to be of interest.