The Helicopter, The First of the VTOL Aircraft

Abstract

SummaryA survey is made in retrospect and prospect of the field of VTOL aircraft. The helicopter and the new VTOL aircraft, although historically separated and differing in appearance, belong to the same family of VTOL aircraft. The dominant parameter in this family is the disc loading, giving the two fundamental types of actuator disc—open disc or rotor and buried disc or fan. Noise and vibration criteria are discussed. The rotor is subject to fundamental aerodynamic limitations, which give speed limits for the pure rotor as well as the rotor compounded with a fixed wing. Rotors are subject to scale effects which limit the economic size of helicopters. Engine requirements for helicopters are discussed. There are three basic types of helicopter. Their characteristics, economics and uses are examined.