X-Wing Helicopters were helicopters with features of jet planes. They were named for the rotor blades which were shaped like an X.
(Note: The background section of this page uses most of the same words as Terra Futura's page on tip-jet helicopters to save time.)
Background[]
The concept of a helicopter originated with Leonardo da Vinci in the 1480s. Along with other flying machines, the helicopter took a while to be successful. The word helicopter was originally a French word derived from Greek. Helicopters were built throughout the early 20th century. However, it was not until 1942 that Igor Sikorsky built the first successful helicopter. With the advent of the R-4, helicopters entered mass production. The R-4 was the only helicopter used in World War II. With the advent of the turboshaft engine, more and more helicopters were being produced. They were larger, faster, and had a higher performance. But there was a problem. The rotor blades caused the helicopter to torque. A tail-rotor was used to stop that. Soon, however, more advanced designs would come.
Tip-Jet Helicopters were first tested in the 1950s and the 1960s. These involved moving the engines into the blades. Two jet pods on the tips of the rotor blades turned the rotor that moved the helicopter. They were practical and lifted more. There was no torque involved. However, early tip-jet designs were inefficient. Worse still, the blades were slowed down too fast for autorotation to allow a safe landing. The solution to this problem came in the early 21st century. Swisscopter America, Inc. came up with the new Dragonfly helicopter. The design used hydrogen peroxide rockets that were more efficient than conventional jet pods. They only emitted water. Also, autorotation was saved. The Dragonfly was easier to fly and handle. Tip-Jet Helicopters were not the only type of jetcopter around. There was also the X-Wing Helicopter.
Description[]
Tech Level: 9-10
The X-Wing Helicopter was named for its rotor blades which were shaped like an X. When taking off, the rotor spun like a conventional helicopter. In horizontal jet flight, the rotor blades were still and rigid. Two jet engines provided propulsion. Compressed air provided a virtual wing surface that acted like a twisted rotor blade. This was the design of the Sikorsky S-72. It was tested from 1983-1988. The transition between vertical and horizontal flight proved to be dangerous. This was a problem inherited by Canard Rotor-Wing Helicopters.