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Glenn W. Goodman, Jr.

Lift On Arrival
New V-22 Tilt-Rotor Aircraft Lacks A Compatible Ground Vehicle

The US Marine Corps and US Special Operations Command (SOCOM) are eagerly awaiting the introduction of the revolutionary Bell-Boeing V-22 tilt-rotor aircraft, now in low-rate initial production. The Marines will take delivery of the first of 390 MV-22s in mid-1999; USSOCOM will get the first of 50 CV-22s in 2003.

The V-22 combines the speed and range of a turboprop aircraft with the vertical takeoff, landing, and hover capabilities of a helicopter. Its unique operational advantages, however, will be offset - at least initially - by the lack of an internally transportable ground vehicle. US Marines and Special Operations Forces, deplaning from V-22s deep in hostile territory in some future scenarios, will be forced to maneuver on foot, equipped only with what they can carry on their backs.

Because the V-22's design was dictated by the requirement to fit on Navy amphibious ships, its cargo compartment is relatively small - 68 inches wide by 59-66 inches high - and thus can only accommodate a narrow vehicle. The V-22's 10-foot-long, 18.5-degree rear loading ramp also presents clearance limitations.

NO COMPATIBLE VEHICLE EXISTS

The obsolete M151 Jeep is the only existing military vehicle that can meet these severe width and height restrictions, and it has mobility and payload limitations. The Army's High Mobility Multipurpose Wheeled Vehicle (HMMWV) is 86 inches wide, and Chenowth Corporation's dune buggy-like Fast Attack Vehicle, used by Marines, Navy SEALs, and Army Special Forces, is 83 inches wide.

The Marine Corps, keenly aware of this vehicle deficiency, approved an operational requirements document (ORD) for a V-22-compatible Light Strike Vehicle (LSV) a year ago this month. However, it has lacked the funds to initiate an acquisition program for a new or modified vehicle. USMC's next opportunity will be its Fiscal Year 2000 budget request, which means a suitable vehicle cannot be fielded until at least several years after USMC MV-22s become operational in 2001. SOCOM, due to its constrained acquisition budget, will wait to piggyback on the USMC effort.

USMC Col. Richard Owen, the program manager for ground weapons at Marine Corps Systems Command, Quantico, VA, told AFJI, "We're getting very strong support from the user community, but the problem these days is that there are so many good, strong requirements competing for a very limited amount of funding." If the program is funded in FY2000, he said, the Marine Corps plans to move immediately into engineering development that year by awarding contracts to two industry firms. Testing of competing prototypes could begin in early FY2001, leading to fielding of the winning design in FY2004.

The Marine Corps and SOCOM, in a joint ORD, have identified key V-22 LSV requirements. The compact wheeled vehicle, which must be able to mount a crew-served weapon such as a .50-caliber machine gun, can't weigh more than about 8,000 pounds when fully loaded and must be diesel-powered. It must accelerate from 0-60 miles per hour in 10-15 seconds and have high off-road mobility and a capability for rapid egress from the aircraft. For Marine missions, the LSV must have a range of 300 miles and carry a 1,500-pound payload - a crew of three plus kit for three days. The SOF requirements are a range of 450 miles and a 3,000-pound payload, including a 4-man crew, for a 10-day mission.

The LSV's severe width and height restrictions make it difficult to design the lightweight, highly mobile vehicle to carry a 3,000-pound payload. A key design issue resulting from the narrow width requirement is the vehicle's lateral stability - its susceptibility to roll over on curves or steep slopes. As Col. Owen noted, "The most challenging requirement, far and away, is having a vehicle that's narrow enough to get into a V-22 but with enough mobility that it won't turn over when we put it through the paces that it is expected to accomplish. That's the toughest technical challenge."

The V-22 aircraft also imposes design load restrictions on the LSV. During flight, the LSV must withstand 16-20 g longitudinal (tiedown) conditions. This theoretically requires the use of 16 10,000-pound tiedown straps and a large number of tiedown points on such a narrow vehicle, potentially hampering rapid offload of the LSV. Emergency egress of personnel from the V-22 as well as the inflight movement of the aircraft's crew chief could also be hindered by the vehicle's tight presence in the 250-inch-long cargo area. Another issue is whether Marines or SOF troops would have to sit in the vehicle during flight.

DEMONSTRATOR VEHICLES

The Naval Surface Warfare Center, Carderock, MD has developed and demonstrated two lightweight, V-22-sized test-bed vehicles in recent years to address critical LSV technical issues. The Helicopter Transportable Multi-Mission Platform (HTMMP) was developed in 1992 and the Joint Tactical Electric Vehicle (JTEV) in 1994-95. Both combine commercial components from the electric vehicle and automotive industries, as well as suspension and handling components from the off-road rally racing circuit. The HTMMP is a four-wheel drive vehicle with a front-mounted diesel engine and a 4-speed automatic transmission; it can carry a 1,600-pound payload. The JTEV, which can carry a 1,500-pound load, is a four-wheel drive hybrid electric vehicle with a smaller diesel engine and alternator, two AC induction motors, and a lead acid battery pack for propulsion. Further testing and upgrading of the two test-bed vehicles is continuing under a joint USMC-Defense Advanced Research Projects Agency (DARPA) effort.

A candidate for a follow-on LSV could emerge from a USMC-DARPA technology demonstration program for a future Reconnaissance, Surveillance, and Targeting Vehicle (RST-V). This V-22-deployable vehicle is being designed from the ground up to maximize mobility, survivability (including silent operation), and integrated onboard surveillance/targeting sensors and command, control, and communications systems. Program officials hope to begin testing at least two prototype vehicles from industry inÊFY2000.

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