VMS SIMULATION OF A VARIABLE DIAMETER TILTROTOR

A joint NASA/Sikorsky simulation study was performed in the NASA Ames Vertical Motion Simulator to evaluate the performance and handling qualities of a Variable Diameter Tiltrotor (VDTR) compared to a Fixed Diameter Tiltrotor (FDTR) during normal and emergency terminal area operations. Pilots from the FAA, NASA, academia, and industry evaluated both the VDTR and FDTR during one-engine inoperative take-offs and approaches and all-engine inoperative landings. The simulation math model was based on NASA’s preliminary design version of the Generic Tiltrotor Simulation code. Both fixed and variable diameter rotor versions exhibited Level One handling qualities during normal maneuvers with both engines operating. In general, the VDTR had a greater power margin and performance in helicopter mode resulting from a lower disk loading requiring 20 to 25% less power at similar thrust levels. This was an advantage during one-engine and all-engine inoperative procedures. This simulation study quantified the performance merits of the VDTR concept and demonstrated that the VDTR offers enhanced performance and terminal area safety for future civil tiltrotor transports. The simulation was also beneficial in identifying areas for further investigation for the VDTR and basic civil tiltrotor concepts.