Inverted Flight

Could a helicopter do steady inverted flight? Theoretically, yes; practically, no. A rotor could produce enough negative thrust to support the helicopter’s weight if it

C. F. = W

FIGURE 5.20 An Ideal Roll

were designed with enough negative collective pitch range. Some radio-controlled helicopter models have demonstrated this capability. No actual helicopters are rigged in this manner, for two reasons. First, it would require a collective control system with twice the normal travel and thus would require more space and weight than a normal system. Second, it would lose the important safety feature of having the down collective stop approximately corresponding to the right position for autorotation.