VTOL

VTOL

INTRODUCTION:

Even before the dawn of jet aircraft, aeronautical engineers have wanted to reduce the amount of runway required by fast aircraft, preferably eliminating runways completely. They wanted an aircraft that takes off and lands like a helicopter but flies with the efficiency of an airplane. These types of aircraft are generally classified either as Vertical Takeoff and Landing (VTOL) or Short Takeoff and Landing (STOL), and the two categories are often grouped together as V/STOL. However, designing such aircraft has been difficult and there have been few successes.

The ability of a helicopter to take-off and land vertically as well as hover makes it an incredibly versatile aircraft; however this maneuverability comes at the expense of speed. For military applications both of these characteristics, maneuverability and speed are of utmost importance.

Where landing sights are unprepared such as in a war zone, or where the available runway is very short such as on an aircraft carrier, an aircraft capable of very short or even vertical take-off becomes a very valuable asset. A ram jet, pulse jet or rocket engine could have been used for vertical take-off but are completely impractical for landing; until the invention of the gas turbine engine, the only practical solution was the rotary wing. All other existing aircraft propulsion systems were incapable of producing enough thrust to overcome the weight of the aircraft without relying on aerodynamic lift from the wings.

From the 1940s until today, slightly more than 40 vertical/short takeoff and landing aircraft have been tested. However, only three have actually gone into production: the British Harrier "jump jet”, the Soviet Yak-38 naval fighter, and the Bell/Boeing V-22 Osprey. Most of the other aircraft were highly experimental or proof-of-concept types never intended to lead to an actual production aircraft.

British Harrier “jump jet"
Soviet Yak-38 naval fighter
Bell/Boeing V-22 Osprey


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