Aircraft taxiing systems

Abstract

Thrust systems for passenger aircraft provide at least one flight engine and a taxi engine wherein all flight engines together provide, in total, a takeoff thrust arranged in a takeoff thrust direction and the taxi engine provides a taxi thrust which does not exceed 15% of the takeoff thrust and is directed substantially the same as the takeoff thrust direction. The taxi thrust is thereby sufficient to taxi the aircraft along a taxi path. In a system embodiment, the taxi thrust does not exceed 7.5% of the flight thrust. In another system embodiment, the flight engines have, in total, a flight engine weight and the taxi engine has a taxi engine weight that does not exceed 10% of the flight engine weight. In a system embodiment, the taxi engine weight does not exceed 7.0% of the flight engine weight. In another system embodiment, the taxi engine has a rated thrust and is configured so that the taxi thrust is within 40% and 100% of the rated thrust. In another system embodiment, the taxi engine includes a rotatable engine portion to divert the taxi thrust over an azimuth angle to assist taxiing along the taxi path. The taxi engine significantly reduces fuel costs because when flight engines are used for taxiing, they operate in a very inefficient region of their rated thrust and consume excessive fuel. The taxi engine also significantly reduces the brake repair and adjustment that is incurred when the flight engines are used for taxiing and the brakes are frequently engaged to counter their high thrust.