Use of headwind and airspeed to achieve a transition to a hover in a helicopter or vtol aircraft

摘要

An improved system and technique is disclosed which enables an aircraft control system to bring an aircraft to hover with no direct measurement of ground speed. The system includes a device for numerically calculating a value for ground speed based on a differentiation of aircraft position as measured from conventional ground reference navigational aids. The computed value of ground speed is compared with values representing heading and true air speed to generate a computed value of wind. The computed value of wind is then resolved into vector components of headwind and crosswind and the headwind component and air speed are summed to provide a signal used to control aircraft speed until zero ground speed is achieved.