I remember a photo of a plane (bi-plane w/ radial?) from the '30's with a single blade prop.; and the Heller "Verti-Jet" helicopter from the late '40's or early '50's has a single blade tail rotor. It has small pulse jets on the tips of the main rotor blades, so the tail rotor is for directional control only, no anti-torque required. It's located at KBDR at the Stratford School of Aviation Maintenance and they are trying to get it to fly again.
It is my understanding that a single blade prop. is the most efficient in converting HP/Tq. to thrust, i.e. moving air. However, the RPM, tip diameter, and tip speed limitations rapidly come into play; a two-bladed prop. of @ 60" is roughly equal to a single blade prop. of @ 110". Designers hang on more and/or thicker blades to adsorb more power for a given diameter/RPM. Allen G. Wiesner KR-2SS/TD S/N 1118 65 Franklin Street Ansonia, CT 06401-1240 (203) 732-0508 flash...@usadatanet.net
