Configuration Study and Performance of a Military V/STOL Roadable Aircraft

摘要

Military operations in central Asia have underscored the vulnerability of vehicles employed in the military scouting, personnel transport, and logistics roles. These vehicles are tied to a road network and can all too easily fall prey to ambushes and improvised explosive devices (IEDs). This state of affairs has led to the increased use of helicopters, which, while effective, incurs much greater costs. The DARPA Transformer (TX) initiative was aimed at providing the United States Marine Corps with terrain-independent mobility. Requirements called for a vertical take-off and landing, road-worthy VTOL vehicle that could fly a 4-person payload over 250 nautical miles, and then safely travel on rough terrain. This paper covers the salient points of Aurora Flight Science's investigation to fill these needs. An extensive configuration study, as well as an investigation of prior art was performed. The history of roadable aircraft teaches us that combining the conflicting requirements of efficient flight with those of driving often results in disappointing performance and questionable utility in both modes of operation. This can be offset to a certain degree by the application of selected technologies and innovative configurations. Aurora Flight Sciences identified a suite of critical technologies that enable dual-mode transportation, VTOL capability, efficient flight performance, and a combat range comparable to today's rotorcraft. These included hybrid electric drive, advanced batteries, variable geometry, ducted fan propulsion systems, advanced lightweight heavy fuel engines, lightweight materials, advanced sensors, and flight controls for stable transition from vertical to horizontal flight. The vehicle designed around these technologies, while thoroughly unconventional, was successful in meeting design goals.