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The V22 Osprey - "Semper Fi!"

Story and Photos by Ted Carlson

Page: 1/2

The Osprey can achieve speeds up to 250 knots and aerial refuel, allowing it to deliver troops quickly and at very far distances, especially when compared to conventional rotary-winged aircraft.

NAS PATUXENT RIVER-BASED HX-21, known as 'Blackjack,' has been instrumental in testing the Osprey and refining it for f leet introduction. The six Ospreys attached to HX-21 all are MV-22B models. Other MV-22B operators include MCAS New River-based VMX-22 (OT&E) and VMMT-204 (FRS), which, although their V-22s are currently back with the manufacturer for modification, are slated to begin receiving airframes again later this year from VMX-22. HMX-1 has also flown the MV-22 but is no longer involved with the program. The Osprey has a pair of Rolls Royce AE1107C turbo-shaft engines, each rated at 6,150 SHP and featuring FADEC. They are the same engines that power the C-130J and are known for their excellent reliability. The V22's engines incorporate IR suppressors which channel ambient air into the exhaust to help reduce the IR signature as well as exhaust deflectors that utilize the 'Coanda Effect' to redirect exhaust gases, further minimizing exhaust heat output. The engines are always running at 100 percent in the helicopter/conversion mode and 84 percent in the airplane mode.

The blade pitch and nacelle angles are dynamic, and effectively are what control the airspeed and thrust. The engine nacelle angle varies from 97 degrees (nacelles facing aft 7 degrees) to straight and level (full forward) to 0 degrees. Should the V-22 lose one engine, the drive train is interconnected via shafting that still drives both propellers; helicopters with twin main rotors, like the CH-46 and CH-47 use a similar principle. The Osprey has a triple-redundant hydraulic system and a number of failures would have to occur in order for one blade to stop spinning - which is unlikely. The most realistic likely cause of a single rotor failure would be combat damage, although with its engines so far apart - unlike multi-engined helicopters with their mechanicals tightly grouped - the Osprey is far less prone to collateral mechanical damage in the event of a hit in one engine. (The V-22's propellers cannot be feathered so with its short wing and prop drag, the Osprey has only a 4.5 to 1 glide ratio.) With a service ceiling of 25,000 ft, the V22 was designed to fly at higher altitudes than helicopters and beyond the reach of many ground threats. With a maximum airspeed of 280 kts, depending on combinations of density altitude, fuel load and weight, the usual maximum straight and level speed is around 240- 250 kts. With its nacelles fully forward, the minimum airspeed is about 120 kts, although there is no need to fly this slowly in airplane mode which would be abnormal and uncomfortable. Typically, the slowest speed in airplane mode is around 160 kts which is the speed used for single-engine aerial refueling. When flying backwards, airspeed is limited to 30 kts and there is a 30 kt crosswind limit. The landing gear extension limiting speed is 150 kts, with the landing gear designed for touchdowns at 100 kts or less.

The Osprey's acceleration is very impressive; from a hover at one end of a runway, it can reach 200 kts by the 8,000 ft marker. At 200 kts in airplane mode, the V-22 flies five degrees nose-up; a product of the CG and airframe geometry (flap angle can be used to offset a nose-up attitude with a slight sacrifice of speed). The flaps can be set at auto, 10, 20, 40 degrees, and 'full' settings. 'Auto' is the normal setting used, which programs the flaps in accordance with airspeed and nacelle settings. Caution is required during aerial refueling since the blades have the potential to get close to the drogue in an overrun situation.
Pilots favor being a bit on the low side in relationship to the drogue, so they can see the drogue better; having the drogue go below the fuselage and out-of-sight is an uncomfortable position to be in and Osprey pilots tend to be ready to pull power back quickly to avoid overruns! Lateral control laws prevent the Osprey from aerially refueling in the conversion mode. Airspeed during refueling varies between 150 and 200 kts. Caution is also required in windy conditions or on a bobbing deck where pilots need to monitor touch-down angles carefully to ensure the nacelle clearance necessary to avoid a nacelle strike. The aircraft's combat range is 600 nm without aerial refueling.

Its self-deployable un-refueled range with extra fuel tanks installed is 2,100 nm (an MV-22B modified for max range and has had three large rigid internal tanks installed - by Robertson Aviation - along with under-wing external tanks); endurance on standard internal tanks only is just over three hours. The Osprey features a trio of INS systems that cross-check each other, making navigation extremely accurate and it will eventually have the MAGR2000 (Miniaturized Airborne GPS Receiver2000) with GPS, anti-jam, and anti-spoof capabilities. The aircraft's AN/AAQ-27 MWIR (Mid-Wavelength Infrared) imaging system mounted under the nose is also used for navigation. The cockpit contains a digital moving map into which mission data can be fed from pre-programmed 'bricks'; a system similar to that found in Hornets and Harriers. The multi-function displays have an array of menus including intuitive system status and fuel tank displays. Primary flight controls include a cyclic TCL (Thrust Control Lever) and ECL (Engine Control Lever). The engine nacelle angle can be manually adjusted to any desired angle using a thumbwheel on the TCL. Being able to use both nacelle angle and engine power gives the pilot great flexibility in keeping the aircraft level in a hover, controlling an accurate forward airspeed with the nose on the horizon, and managing stiff crosswinds. In future, the V-22 will feature automatic nacelle angle capability based on airspeed.




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