In a helicopter the articulated head and tail rotor gearbox are required to be a very high specification design using the best materials and requiring frequent and costly maintenance.
在直升机的阐述头和尾桨变速箱都必须是一个非常高规格的设计使用最好的材料和需要频繁和昂贵的维修。
2
Helicopters require a tail rotor to counteract the rotor torque; this and the articulated head complicate flying, construction and maintenance enormously.