Tilt-rotor aircraft: Bell XV-3 (left) and Bell XV-15 (right)

Photo courtesy NASA

Fly Like a Bird, Hover Like a Bee

The Osprey is a type of vertical takeoff and landing (VTOL) aircraft with a tilt-rotor design. The VTOL concept is an old idea stemming from the German air force at the end of World War II. After the war, the U.S. Navy developed two experimental VTOL fighter aircraft, the Pogo and the Salmon. However, the programs were cancelled because of technical difficulties. In 1958, the U.S. Air Force developed the Bell XV-3, which was the first successful VTOL to hover (it was not tested in airplane flight).

Tilt-rotor aircraft: Bell XV-3 (left) and Bell XV-15 (right)

Photo courtesy NASA

After the XV-3 program proved that the tilt-rotor concept was feasible, Bell developed the XV-15 tilt-rotor that was tested by NASA. In July 1979, the XV-15 became the first aircraft to tilt from helicopter to airplane and back. It was also capable of traveling 346 miles per hour (557 kph) in airplane mode. The success of the tests lead to the expansion of the program, which was subsequently renamed the V-22 Osprey. There are three configurations of the Osprey depending upon what it's being used for, such as search-and-rescue, medium-range assault or long-range special operations. While three branches of the U.S. Armed Forces -- the Marines, Navy and Air Force -- will use the Osprey, Bell is also exploring its design for possible civilian uses.

V-22 osprey transitioning from helicopter to airplane mode

Photo courtesy U.S. Navy

The Osprey has two, large, three-bladed rotors that rotate in opposite directions and produce lift. Because the rotors turn in opposite directions, there is no need for a tail rotor to provide stability as in a helicopter. The wing tilts the rotors between airplane and helicopter modes and generates lift in the airplane mode. The Osprey can convert smoothly from helicopter mode to airplane mode in as few as 12 seconds.

The major advantages of the Osprey over a helicopter are:

  • Longer range - The Osprey can fly from 270 to 580 miles (453 to 933 km).
  • Higher speed - The Osprey's top speed is 315 mph (507 kph), which is twice as fast as a helicopter's top speed.
  • Increased cargo capacity - The Osprey can carry 10,000 pounds (4,536 kg) of cargo or 24 troops.

The advantage of the Osprey over an airplane is that it can take off, hover and land like a helicopter. This makes is more versatile than an airplane for such missions as moving troops to remote areas, especially those without landing strips, or conducting long-range rescue operations at sea.

In the next section, we'll take a look at the Osprey's systems.