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H. Thomas Hayden
recently concluded over 35 years of service,
which included the Agency for International
Development, the Marine Corps, defense industry
and the Pentagon. His specialties are Intelligence,
Counterinsurgency Operations, Counter-terrorism,
and Joint Concepts Development and Experimentation.
His Marine Corps assignments have included
command of two separate battalions; AC/S G-2,
4th MARDIV & AC/S G-2 FMFEurope; Branch Head,
HQMC, Special Operations and Low Intensity
Conflict (SO/LIC); Special Assistant to the
Assistant Secretary of Defense for SO/LIC;
and, Senior Program Analysts at HQMC with
the Joint Staff and DoD at the Pentagon. Overseas
assignments included Vietnam, Japan & Okinawa,
Europe, Central America, Saudi Arabia and
Kuwait, Somalia, Singapore, Philippines, and
Colombia. He has an MBA (Pepperdine) and an
MA in International Relations (University
of Southern California). He has written two
books and is working on a third.
Thomas
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October 13, 2004
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When Congress reconvenes after the election, there will be a number of Defense programs cut to make up for the budget deficit caused by the Afghanistan and Iraqi Wars. The MV-22 Osprey tilt-rotor aircraft will not be one of them.
The key word in Defense acquisition today is transformation. The MV-22 Osprey will truly transform the way the Marine Corps conducts amphibious assaults and assist other Services in their needs for air-sea rescue and recovery operations.
The MV-22 Osprey is a vertical/short takeoff and Landing (VSTOL), medium-lift, military transport aircraft that the Marine Corps have needed for many years. It is twice as fast, can carry three times as much, and goes six times farther than the aging CH-46Es and CH-53Ds, both of which the Osprey is replacing. The MV-22 Osprey's 38-foot prop-rotor system and engine/transmission nacelles mounted on each wing tip allow it to operate as a helicopter for takeoff and landing. Once airborne, the nacelles rotate forward 90 degrees, converting the aircraft into a high-speed, high altitude, fuel-efficient turbo-prop aircraft.
The MV-22 Osprey will join the Expeditionary Fighting Vehicle (EFV) and the Landing Craft Air Cushion (LCAC) as an integral part of the Seabasing capabilities necessary to execute Expeditionary Maneuver Warfare. If the MV-22 continues its current run of success in testing and is fielded as planned, it will change everything about how maneuver warfare is conducted.
The MV-22 Osprey, as much an airplane as a helicopter, had a "publicity" problem, primarily resulting from two highly publicized mishaps that killed 23 Marines four years ago. The investigation into these accidents resulted in the discovery and subsequent resolution of an aerodynamic condition affecting all rotorcraft but primarily linked to the MV-22 Osprey - a condition called "vortex ring state" (VRS).
Proceedings, published by the U.S. Naval Institute, published an article by LtCol Kevin Gross, September 2004, which explained the problems of the MV-22 Osprey much better than I can. LtCol Gross wrote:
"On the evening of 8 April 2000, a flight of four MV-22s was conducting a night assault mission to a small airfield in Marana, Arizona, when the second airplane (or "Dash 2") rolled nearly inverted on short final and crashed, killing all on board. During the subsequent investigation, it was discovered that the lead aircraft was almost 2,000 feet higher than planned at the initial point (the location where the conversion from airplane mode to VTOL [vertical take-off and landing] mode for landing begins). The lead aircraft entered a steep approach profile with a high rate of descent while it rapidly decreased speed for landing. During the rapid deceleration, Dash 2 no longer could remain in trail as briefed but came abeam of the lead's right side. To return to the trail position, Dash 2 flew slower and with a higher rate of descent than his lead. At approximately 300 feet above ground level, with a more than 2,000-feet-per-minute rate of descent and with less than 30 knots forward airspeed, the mishap aircraft started a right roll that could not be corrected by the pilot.
The mishap investigation, having ruled out all other possibilities, soon focused on the extremely high rate of descent at low altitude as the primary cause of the accident. It was concluded that during the descent, the aircraft entered an aerodynamic condition called vortex ring state (VRS)."
LtCol Gross explained that VRS is an aerodynamic condition in which the tangential airspeed at the rotor is small (associated with low forward airspeed) and the airspeed perpendicular to the rotor is high (associated with powered rate of descent). VRS typically becomes a concern below 40 knots forward airspeed at high rates of descent. To reach this condition, power must be applied during the steep descent. In layman's terms, when the induced velocity equals the vertical velocity, VRS may occur, causing a reduction in rotor lift or increased sink rate. VRS can occur as a rotorcraft settles down through its own vortex field at slow forward airspeeds.
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When they knew where the VRS boundary was located, how the aircraft responded during VRS, and the proper recovery procedures and techniques, their focus turned toward avoidance of VRS. The engineers made two changes to the avionics displays that increased the pilot's situational awareness during low-speed, high-rate-of-descent flight.
With their test effort behind them, the Integrated Test Team at Naval Air Station Patuxent River, Navy and Marine Corps test pilot facility, is confident they fully understand the location of the VRS boundary for the tilt-rotor, the aircraft roll-off characteristics during steady maneuvers within the boundary, and the immediate and effective recovery procedures. They have developed avionics warnings to aid pilots in avoiding high rates of descent at low airspeed and the fleet has a better understanding of the capabilities of the MV-22 Osprey and will be confident to fly in harm's way knowing vortex ring state never will be encountered again.
Lieutenant Colonel Gross was the government flight test director for the MV-22 program from August 2002 to August 2004 and participated in several test flights. He currently is assigned to the V-22 Joint Program Office at Patuxent River, Maryland. He would like to acknowledge Tom Macdonald's and MV-22 lead government engineer Ray Dagenhart's contributions to his article in Proceedings.
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