We were sitting in the cockpit of a Bell/Boeing V-22 Osprey, staring down the Pax River runway. I was in the left seat; Doug Isleib, United States Marine Corps, was in the right. He had given me the brief, let me watch him fly the thing a little, and now it was my turn.
I checked the torque on the two Allison T406-AD-400 turboprop engines; made sure both engine nacelles were pointed straight up, spinning 38-foot, three-blade rotors at 100 percent rpm; then I eased the throttle — there is only one, called a thrust-control lever — forward toward 70-percent torque. The Osprey rocked on its gear, then lifted off the runway.
Up I climbed into the azure blue to the dizzying height of eight feet, trying desperately not to overcontrol the stick in my right hand or the rudder pedals under my feet.
"Higher," Isleib urged.
A push on the go lever under my left hand gave me more torque. The Osprey rose higher, higher, up to 30 feet.
Semi-stabilized, not rocking too much, drifting sideways only a little — the operator in the control room of the simulator had the wind velocity knob on zero — I eased in rudder and let the Osprey slowly swap ends.
In the helicopter mode the control stick acts like a helicopter cyclic, adjusting the swashplates under the two counterrotating rotors: a push forward lowers the nose; a pull back raises it, etc.
With rotor rpm always at 100 percent, the single thrust lever controls the torque on both engines and thereby forces the rotors to take larger or smaller bites of air to keep the rpm steady.
So far the Osprey was just a heavy twin-rotor helicopter, although a funny one with the engines and rotors mounted on each side instead of fore and aft. It wasn't going to stay that way very long, though. Now for the magic.
I used my left thumb on a little wheel on the thrust lever, rotating it forward. I glanced at the readout on my left multifunction display (MFD): 89 degrees...88...all the way down to 80.
The Osprey was moving forward now, accelerating from the hover. I kept thumbing the engines forward, tilting the rotors.
At 40 knots indicated the wings began producing lift; I felt the transition as the three flight-control computers began to give me control of the twin rudders, elevators, and flaperons — full-span flaps and ailerons combined — while reducing my control of the rotor swashplates. I kept the nacelles coming down toward the horizontal. The speed built rapidly.
Gear up, a little nose down to help accelerate, then back on the stick to raise the nose above the horizon to establish a positive rate of climb as the Osprey completed the transition to wing-borne flight.
"Oh, wow!"
I was amazed at how easy the V-22 Osprey is to fly. True, this was just a simulator, but ooh la la. The only control that wasn't instinctive to a fixed-wing pilot was the thumb wheel that controlled the position of the nacelles, or engines. With both engines controlled through one throttle/thrust lever, the flaps in full automatic mode, and no cowl flaps or boost pumps or prop controls, the airplane is a dream to fly.
Computers make it so. These magic boxes allow an average flesh-and-blood pilot like me to control a dynamically unstable machine that truly would be beyond my physical capabilities if I had to control all the variables manually.
Of course, I mused, if an engine out there on the end of a wing fails, it's going to take more than computers to keep this thing in the air. I asked Isleib, who is the deputy program manager for the Marine Corp's version of the V-22, about that. "The pilot has only one throttle — what does he do when an engine packs it in?"
"Each rotor is turned by a large gearbox," he said, "and the gearboxes are interconnected by a drive shaft. When one engine quits, the remaining engine automatically drives both rotors."
Each engine is rated at 5,183 horsepower, but in a single-engine emergency the operating engine can produce as much as 6,834 horsepower, which puts 2,670 horsepower to each rotor. The rest of the power is lost in the drivetrain and bled off by accessories. Still, that's enough power to get the airplane down safely, Isleib said, although the pilot may have to dump fuel or cargo for a vertical landing.
Three separate hydraulic systems drive the three actuators that tilt each engine nacelle, a triple-redundant system; only one actuator is required to rotate a nacelle. If all three systems were to fail, the pilot would have to complete the flight at that nacelle position, a highly unlikely emergency, Isleib said. Still, a conventional landing with the engines in the horizontal position would shear off the prop-rotors, which are engineered for "broom straw" failure — shredding instead of breaking off in big chunks. (Running takeoffs in the Osprey are made with the engines tilted up between 50 and 70 degrees.)
Vertical takeoff and landing (VTOL) machines have been around since the Flying Bedstead of 1953, when Rolls-Royce mated two jet engines and directed the exhaust downward through controllable nozzles.
Other VTOL airplanes followed through the years, some successful, some less so. Among the more notable VTOL experiments were the Bell XV-3 and XV-15; the Hawker-Siddeley P-1127, which led to the Kestrels; a modified Dassault Mirage fighter, the Mirage III-V; the Ryan XV-5A; the Lockheed Hummingbird; the LTV XC-142A four-engine tilt-wing transport; and, of course, Harriers and Yakovlev Yak-38s.
All of these airplanes sacrificed performance or payload to achieve VTOL or VSTOL (very short takeoff and landing). The Osprey is revolutionary because advances in computers, engines, and composite construction made the performance tradeoffs minute or nonexistent. Seventy percent of the airplane by weight is composite material, so the added weight of gearboxes, driveshaft, and computers still leaves plenty of payload. With 12,000 pounds of fuel, the Marine version of the V-22 can lift up to 20,000 pounds of internal cargo or 15,000 pounds externally, or it can carry 24 combat-ready Marines over 500 nm at 250 kt. The quantum leap in capability and survivability that the Osprey represents has the Marines and Air Force pretty excited.
Four preproduction airplanes are currently being tested at Naval Air Station Patuxent River, Maryland. The first airplane off the production line was scheduled to arrive at Pax River in May. Ospreys are scheduled to begin operational deployments in 2003. The Marines plan to buy 360 of them; the Air Force, 50; the Navy, 48.
As you might expect, the cockpit is completely computerized — there are only three tiny conventional gauges: a gyro, airspeed indicator, and altimeter — and designed to be compatible with night-vision systems. Each pilot has two multifunction displays, each of which has a menu that can access about 200 pages. In the tactical mode, one of the MFDs presents a digital map display that can be used as a flight director, with flight plans prepared on the ground and loaded into the computers before takeoff. Sensor data from the forward-looking infrared unit in the nose chin turret is integrated into the tactical presentations. The Air Force variant of the Osprey will add terrain-following/avoidance radar.
I confess that the sight of all those computer screens and push buttons horrified me. "The pilots will be in school forever learning all this stuff," I moaned.
"Oh, no," Isleib said. "They'll teach themselves on a computer."
Even the aircraft maintenance is computerized. There will be no library of paper maintenance manuals; the wrench toter will plug his or her laptop into the airplane's computers, which will diagnose the health of the various systems, tell what needs to be done, and explain how to do it.
"The main thing left on our dream list," Isleib told me, "is a turreted, three-barreled .50-caliber machine gun for the nose. The pilot or copilot could use it to suppress enemy fire when coming into [a landing zone]."
All of this for just $39.5 million in 1994 dollars (do you still have any of those?). That's a lot of kale, but the Osprey is a lot of airplane.
Civilian versions are also under development. The tiltrotor will be a good urban neighbor — less noisy than a twin-rotor helicopter when hovering or a conventional turboprop in flight, and requiring little room to operate. Its vertical or near-vertical takeoff and landing capabilities, its ability to carry a serious number of people or amount of cargo, and its speed and range make the V-22 seem like the answer to a lot of prayers — urban short haul, VIP limo, medevac, search and rescue, oil-rig transport, super bush plane?the possibilities seem endless.
Coming back to the airfield, I swung the Osprey into a steeply banked turn to quickly bleed off airspeed while I thumbed the engines into the vertical position. They came up fast, at 8 degrees per second. Soon I was slid-ing down the glideslope with the engines pointing straight up. Am I good or what?
I rotated the engines to 5 degrees aft to help stop forward motion and killed a few rats with the control stick. Finally I got things a bit sorted out, was more or less in the vicinity of the runway, and not drifting too terribly much, so I let the Osprey settle. At the bottom the pilot-induced oscillations got a wee bit large and the right engine nacelle struck the runway, freezing the simulator.
"Oops, " I said. "Sorry about that."
"Don't sweat it," Isleib replied, seemingly unconcerned. "We'll dab some putty and paint on it and no one will ever notice the dents."
The V-22 will appear in Coonts' new novel, Cuba. Coonts and his wife, Deborah, currently own a Breezy, a Piper PA-22/20, a Beech S-35 Bonanza, and a Piper Cub. E-mail the author at [email protected] or visit the Web site ( www.coonts.com).
Related Articles
