Abstract: A helicopter external cargo suspension system (12) has load sensors (19,20) at each suspension point for sensing the magnitude of a load (32) at each suspension point. A delay period (FIG. 6) is determined based on the magnitude of the load, and a load is released if one of the following failure modes occurs for a period which exceed the delay period: one of the suspension points is unloaded, the magnitude of the load exceeds a maximum threshold magnitude, or if the distribution of the load, as indicated by the difference in magnitude at each suspension point, exceeds a difference threshold magnitude. If the magnitude of the load is below a minimum threshold magnitude, the load will be carried by one of the suspension points in response to a failure of the other suspension points.

Abstract: Control law system for the collective axis, as well as pitch and roll axes, of an X-Wing aircraft and for the pneumatic valving controlling circulation control blowing for the rotor. As to the collective axis, the system gives the pilot single-lever direct lift control and insures that maximum cyclic blowing control power is available in transition. Angle-of-attach de-coupling is provided in rotary wing flight, and mechanical collective is used to augment pneumatic roll control when appropriate. Automatic gain variations with airspeed and rotor speed are provided, so a unitary set of control laws works in all three X-Wing flight modes. As to pitch and roll axes, the system produces essentially the same aircraft response regardless of flight mode or condition. Undesirable cross-couplings are compensated for in a manner unnoticeable to the pilot without requiring pilot action, as flight mode or condition is changed.

Abstract: A circulation control rotor system in which butterfly valves (44, 46) control the flow of compressed air from a plenum chamber (40) to the rotor blades (14). Each has an actuator (48, 52) positioning the valve in accordance with a control input and in which a spring loaded averaging linkage (120) between adjacent valves around a plenum chamber circumference acts to position the valve at an average position of the two adjacent valves if a fault in the actuator or within its control or power system should develop. Should such a fault develop, as determined by a comparison of actual valve position with command position, the faulty valve's actuator is shut down.