Vertical takeoff and landing (VTOL) emerged as a concept, which was soon to be successfully implemented. Dr A.A Griffith, in 1941 who was then the chief engineer of Rolls Royce ltd. put forward this idea in his paper to the aeronautical research council. According to wikipedia.org a vertical take-off and landing (VTOL) aircraft is one that can hover, take off and land vertically. This classification includes fixed-wing aircraft as well as helicopters and other aircraft with powered rotors, such as cyclogyros/cyclocopters and tiltrotors.
Types of Vertical Take-off & Landing (VTOL) Aircraft
The various possibilities of facilitating VTOL using jet lift are as follows.
1. WHOLE AIRCRAFT IS TILTED: also referred to as vertical attitude take off and landing, the aircraft is made to takeoff in a vertical position. After gaining sufficient altitude the aircraft flattens out to a normal horizontal flight. This seemed to be the most natural idea and it has its share of advantages and disadvantages. The advantage lays in the fact that no movable wings or propellers are needed. On the other hand complicated devices for launching were needed. Great thrust too was required at no forward speed. Thus if engine failure occurred at an initial stage there was no chance of making a safe landing.
2. ENGINES OR PROPELLERS ALONE ARE TILTED: This design did away with the earlier design complexities but it too had to content with various challenges. The location of the engine posed a great difficulty. The condition was to locate the engines in such away that the propellers slipstream or jet efflux would clear the aircraft for all positions of the engines