The Defense Advanced Research Projects Agency (DARPA) is soliciting proposals on the design, development and demonstration of a vertical takeoff and landing (VTOL) experimental aircraft (X-Plane) with exceptional performance in vertical and cruise flight and operational capability through transition from vertical to forward flight, according to a Feb. 25 broad agency announcement (BAA) posted on Federal Business Opportunities.
The purpose of the program is to champion the design and development of subsystem technologies and integrated air vehicle configurations that will enable radical improvements in VTOL flight. The program will demonstrate an aircraft capable of sustained flights at high speeds, improved hover and cruise efficiencies that are significantly greater than contemporary rotary-wing aircraft and increased useful load fractions and aircraft functionality, DARPA said in the BAA.
DARPA specifically wants the X-Plane to fly at sustained speeds between 300 and 400 knots and demonstrate aircraft hover efficiency within 25 percent of the ideal power loading (at standard sea level conditions) and cruise lift-to-drag ratio no less than 10. The X-Plane will be designed to have a gross weight between 10,000 and 12,000 pounds, a useful load no less than 40 percent of the gross weight and a payload capacity of at least 12.5 percent of gross weight.
DARPA split the X-Plane program into three phases over 52 months, with first flight at 42 months after award. The BAA is for Phase I, which is broken into two subparts: Phase IA, a six-month conceptual design effort, and Phase IB, a 16-month preliminary design and technology maturation effort. A proposers’ day was held March 14 and proposals are due June 4.
DARPA budgeted $130 million for the X-Plane award with $47 million available in Phase I. DARPA anticipates multiple awards for Phase I with a single award expected for aircraft development and flight test in Phases II and III.
DARPA said it seeks new VTOL technologies because the current inventory of vertical flight machines, dominated by the large, open rotor helicopter, is inadequate for flight at high speeds covering long ranges and hovering under extreme conditions. Though DARPA seeks to develop these advanced technologies, it does not desire a pre-production type aircraft for any specific operational effort but instead technologies with the potential to be applied to future objective concepts.
Helicopters, or rotary-wing aircraft, have an advantage of being able to maneuver in tight areas, land in unprepared areas, move in all directions and hover in midair while holding a position, making them the right platform for transporting troops, surveillance operations, special operations and search-and-rescue missions, DARPA said in a statement. But helicopters are slower, leaving them more vulnerable to damage from enemy weapons. Though engineers have improved the speed of fixed-wing aircraft over the years, attempts to increase efficient VTOL speed have stalled.