Doppler Control of Ejection- Type Emergency Barrier

A control system utilizing doppler radar and analog computing techniques has been developed which will actuate an accelerator used to raise a cross-deck cable at such time that this emergency barrier will miss the nosewheel of tricycle landing-gear aircraft. A doppler radar antenna located on the aft end of the flight deck and oriented forward is used to measure the velocity of the landing aircraft. A zero-position doppler radar antenna located on the side of the flight deck and oriented perpendicular to the velocity doppler radar is used to determine the instant at which a given point on the aircraft is at a specified distance from the barrier. When the reference point of an aircraft traveling with a speed greater than 35 knots passes the zero-position, an analog computer unit is initiated which determines by means of appropriate circuits and parameters the proper instant for actuating the barrier accelerator.