After many delays and cost escalaltions, as always, the V-22 looks all set to become the first VTOL transport to enter service that was not a
The idea of vertical lift transports with fixed wings has fascinated the aircraft industry for over half a century and in recognition of the impending
success of the V-22 here is look back at those attempts that went before it.
In this post I will also limit myself to those types which actually got built as, although fascinating in their own right, the drawing board concepts
never really added any practical knowledge to the field.
1 Fairey Rotodyne
This was the first fixed wing VTOL transport to take to the air and was basically a 40 seat turboprop airliner with a huge rotor on top. The rotor was
in fact not connected to the two wing mounted Napier Eland engines, as you might imagine, but was instead powered by very small tip mounted jets which
were used for take off and landing, with the rotor then being allowed to free wheel during forward flight in the manner of an autogiro, where it added
to the lift created by the wings.
In fact this arrangement worked perfectly well, a great acheivemet for 1957 when it flew, but the tip jet system led to insurmountable noise issues
which killed off any hope of commercial operations after many years of developent and even an evaluation by the RAF led nowhere. In terms of size and
capacity this fifty year old prototype was remarkably close to todays V-22.
2 Hiller X-18
This was the first transport sized VTOL transport to fly in the USA and was also the first to do without a helicopter style rotor
Its tilt-wing layout was thought to be simpler and stronger than attempting to tilt the engines or driveshafts themselves (which arrangement had
already been flown on earlier, smnaller test vehicles in the US). Unlike the Rotodyne, this was not intended for service in its own right as it was a
technology demonstrator for a larger machine, but it deserves inclusion as it could
have operated in the transport role if required as it was
perfectly serviceable and large enough and was, to all intents and purposes, a genuine transport aircraft. It was powered by three engines, two wing
mounted Allison T40 turboprops plus a Westinghouse J34 jet engine for pitch control. First flight was in Nov 1959 and on its 20th flight it had a
propeller pitch control problem at 10,000 ft and went into a spin. It was recovered before impact, but was grounded, having never achieved hover.
3 Curtiss Wright X-19
Based on a layout proven by a much smaller test vehicle (as so many of these aircraft are) called the X-100, the design of this aircraft began as a
civil executive transport called the X-200.
With no market for such an aircraft apparent Curtiss Wright were ready to pull the plug when the USAF showed interest in sponsoring this design as
their entry in the Tri Service Assault Transport comptetition, whence it acquire the designation X-19. The first hover was made in Nov 1963, in 1965 a
transmission failure allowed the crew to prove the validity of its ejector seat arrangement, which was a success and when the project was canelled
four months later it had made 50 flights, but only for a total of four hours.
4 Bell X-22A
This was the US Navy sponsored entry for the above mentioned Tr-Service Assault Transport.
It was powered by four General Electric T-58 turboprops driving four 3-bladed ducted propellers, unlike the X-19 however, these engines were cross
linked in case of power failure.
The X-22A made its first hovering flight in March 1966 but was lost in an accident after only three hours of flying. The second prototype appeared in
1967 and completed hundreds of successful transitions. This highly successful demonstrator continued flying until 1980 and ran up about 200 hours
5 LTV Hiller Ryan XC-142
The XC-142 aircraft was the third aircraft evaluated in the Tri-Service Assault Transport Programme ans was by far the largest. Powered by four
General Electric T-64 turboprobs each driving a 15ft diameter propeller, the wing of the XC-142 rotated through 100 degrees which allowed it to hover
in a tailwind.
It first flew as a conventional aircraft in september 1964 with the first hover demonstrated that December, the first transition quickly followed in
Jan 1965 and the type went on to accrue 420 flying hours. The XC-142 was said to suffer from excessive vibration and noise, resulting in a high pilot
workload and four of the five aircraft built were damaged in heavy landings.
6 Dornier Do-31
The Do-31 remains the worlds only VTOL jet transport to fly. Intended to carry troops and to support other V'STOL types such as the Harrier in the
field it was flown for the first time in 1967 and carried out a test programme until 1971.
Power came from a pair of Pegasus engines mounted in underwing pods and a bank of Rolls Royce RB.162 lift engines mounted in pods on each outer wing.
A proposed 100 passenger civil transport variant was designated the Do-231.
[edit on 6-10-2005 by waynos]
[edit on 6-10-2005 by waynos]