Higher speeds, increased efficiency, elegant designs are the focus of new VTOL X-Plane
DARPA, an organization devoted to maintaining the technological superiority of the United States military, has launched a new VTOL X-Plane program designed to yield advancements in vertical take-off and landing (VTOL) technology.
"For the past 50 years, we have seen jets go higher and faster while VTOL aircraft speeds have flat-lined and designs have become increasingly complex," said Ashish Bagai, DARPA program manager. "To overcome this problem, DARPA has launched the VTOL X-Plane program to challenge industry and innovative engineers to concurrently push the envelope in four areas: speed, hover efficiency, cruise efficiency and useful load capacity."
The versatility of helicopters and other VTOL aircraft make them ideal for a host of military operations, DARPA said. Currently, only helicopters can maneuver in tight areas, land in unprepared areas, move in all directions, and hover in midair while holding a position. This versatility often makes rotary-wing and other VTOL aircraft the right aerial platform for transporting troops, surveillance operations, special operations and search-and-rescue missions.
Compared to fixed-wing aircraft, however, helicopters are slower leaving them more vulnerable to damage from enemy weapons. Special operations that rely on lightning-quick strikes and medical units that transport patients to care facilities need enhanced speed to shorten mission times, increase mission range, reduce the number of refueling events and, most important, reduce exposure to the adversary.
DARPAs VTOL X-Plane program seeks a demonstrator aircraft designed 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 VTOL experimental/demonstrator aircraft 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 the gross weight.
The VTOL X-Plane program is divided into three phases extending over 52 months, with first flight at 42 months after award. Phase I is broken into two sub-parts, Phase IA and Phase IB. Phase IA is a six-month conceptual design effort while Phase IB is a 16-month preliminary design and technology maturation effort. Proposals for the remainder of the program will be solicited from Phase I prime performers towards the end of the first phase, and must be submitted by the time of the preliminary design review (PDR). It is anticipated that one award will be made for Phases II and III. All detailed design, development and integration efforts will be performed during the second phase. The total planned budget for award is on the order of $130 million, with $47 million available in Phase I. DARPA anticipates multiple individual awards in the first phase.
"We have not made this easy," Bagai said. "Strapping rockets onto the back of a helicopter is not the type of approach we're looking for. The engineering community is familiar with the numerous attempts in the past that have not worked. This time, rather than tweaking past designs, we are looking for true cross-pollinations of designs and technologies from the fixed-wing and rotary-wing worlds. The elegant confluence of these engineering design paradigms is where this program should find some interesting results."