Abstract: A rotor hub fairing system includes an upper hub fairing, a lower hub fairing and a shaft fairing therebetween. The rotor hub fairing system reduces the total drag on a dual, counter-rotating, coaxial rotor system. Other aerodynamic structures may be mounted to the shaft fairing, hub fairings and airframe to facilitate flow around the upper and lower hub fairings to reduce flow separation and drag.

Abstract: A rotorcraft control system for effectuating primary flight control and high harmonic control. The control system preferably including at least one primary flap, at least one primary actuator used principally for primary flight control, at least one secondary flap, and at least one secondary actuator used principally for high harmonic control. The at least one secondary flap and the at least one secondary actuator preferably may also be used to enhance primary flight control under some flight conditions.

Abstract: A nozzle for a gas turbine engine is provided with undulations on a core and/or fan exhaust flow nozzle. An annular wall defines a fluid flow passage and includes a base portion and an adjoining exit portion. The base portion is typically generally frustoconical in shape and includes an arcuate contour in an axial direction. The exit portion includes undulations in a generally radial direction that provide lobes and troughs each respectively including trailing edges. One of the lobe and trough trailing edges are recessed from the other of the lobe and trough trailing edges in a generally axial direction. The other of the lobe and trough trailing edges form apexes with the apexes provided on tabs. The troughs extend radially inward in the axial direction towards the trough trailing edges.

Abstract: A rotor hub fairing system includes an upper hub fairing, a lower hub fairing and a shaft fairing therebetween. The rotor hub fairing system is sized and configured to reduce the overall drag on a dual, counter-rotating, coaxial rotor system. Preferably, the rotor hub fairing is fully integrated. The shaft fairing preferably includes a minimal thickness at the midsection to reduce drag with an increasing thickness adjacent the upper and lower hub fairings to reduce the flow separation on the hub fairing surfaces without overly excessive drag. Other aerodynamic structures, such as a horizontal splitter and/or a plurality of turning vanes may be mounted to the shaft fairing to facilitate flow around the upper and lower hub fairings to reduce flow separation and drag.