Sikorsky S-72

The Sikorsky S -72 X-wing was a U.S. experimental aircraft, which was a hybrid of helicopter and Starrflüglertechnologie. It is thus expected to composite flight screwdrivers, because of the stop rotor but also to change aircraft. The S -72 was developed 1983-1988 by the helicopter manufacturer Sikorsky, the NASA Ames Research Center and the Defense Advanced Research Projects Agency. The program initially received the designation RSRA (Rotor Systems Research Aircraft, German experimental aircraft for rotor systems).

The aim of the program was to evaluate the ability of the vertical starting a helicopter with the high flight performance of an aircraft to combine an efficient manner.

Technology

The X-wing took off vertically like a helicopter, with its centrally driven rotor of four rigid rotor blades. The rotor has to be stopped during the flight and is locked in the X position, wherein the rotor blades produced as an additional X-shaped part of the wing lift. The main impetus was provided by two rigid wing like a conventional aircraft. The tunnel was driven in this flight phase by two of the fuselage mounted jet engines.

During rotor operation, the X-Wing was not controlled as in a conventional helicopter by tilting the plane of the rotor by means of the swash plate. Rather, compressed air was passed through the rotor blades, and is blown out by means of computer-controlled valves during the rotation of certain parts of the blade, so that the corresponding lateral movement has been reached. This technological approach has been pursued at the Boeing X - 50, but not with the tilt-rotor V-22 Osprey aircraft.

History

In the early 1970s, opportunities were sought to increase speed, performance, reliability and safety of helicopters. Also, Noise, vibration, and maintenance costs should be reduced. The Sikorsky Aircraft Division of United Technologies Laboratories built in 1983 two RSRAs. The NASA Langley Research Center in Hampton, Virginia began with the first test and misplaced then the program at the Ames Research Center in Mountain View, California, for extensive flight tests.

The RSRA first flew at the Ames - Dryden Flight Research Facility at Edwards, California in the spring of 1984. These tests served to demonstrate the Starrflüglerfähigkeiten and the power spectrum.

Based on a new series of tests was carried out in 1986 with the X-wing and 1987 was an evolved version, which was used to study new rotor systems and assistive technologies during the flight. NASA and DARPA commissioned Sikorsky now to rebuild one of the original RSRAs the new X-wing version and provide a demonstration model for the X-wing concept.

The X-wing should neither replace nor fixed wing helicopter. It was intended for special applications, which require both capabilities: both the efficiency of a helicopter at low speed and the high speed of airplanes. The tactical objectives of the mission should be air -to-air and air -to-ground defense and anti-submarine defense, airspace surveillance, electronic reconnaissance and search and rescue count.

The modified X-wing was delivered on 25 September 1986 at Ames - Dryden. After taxi tests were first flights take place in Starrflüglermodus and without rotor in December 1987. The contract with Sikorsky ran out at the end of the month and was not renewed. The program officially ended in January 1988 for unknown reasons.