VTOL transports

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 helicopter.

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 flying time.

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]

Waynos what do you think about the posiblity for the next heavy VTOL transport for the USA to be a jet powered one. I have seen drawings of the cv-44 but what about jet powering them for even faster speeds etc.

Hmmm, interesting question. I suppose it depends on the form it would take. One thing demonstrated by the Do 31, which seemed to represent 'the future' at the time, was the drawback of having banks of lift engines wich are just dead weight in forward flight, and thus eat into the aircrafts useful load for either payload or fuel, coupled with the impracticality of relying on vectored thrust engines like the Pegasus, even though they appear to be the answer to the problem, simply because no such engine was capable of lifting a loaded transport vertically by itself.

Today I suppose you could picture something like an A318 sized transport with short wings and tip mounted rotating Trent turbofans, but would would such huge engines be viable on such a small aircraft? Something about it just doesn't ring true and large rotor-like props do seem to be the most efficient way to acheive vertical lift in a transport, even with modern turbofan technology. I think there may be scope for an XC-142 style tilt wing transport in the not too distant future but I don't think Jets are practical at the moment.

[edit on 6-10-2005 by waynos]

Hey I read that you can now buy a M400 Moller SkyCar for US$3.5 million in this years Neiman Marcus' Christmas catalog.

3.5 million for the Moller SkyCar

So much for his vision of revolutionizing transportation for people. You might as well spend a extra million and buy a commercial helicopter

I remember reading about the Moller Skycar in a huge four page spread with photo's in 'Autocar' around 1989, and it still wont work properly. You might as well throw your money down thew toilet and find another way to kill yourself

This thing is so impractical its untrue, and you don't need to think about it for very long to see why its a stupid concept, there are already far too many crashes on the roads, never mind putting unregulated traffic into the sky!

can't you buy a helicopter for less than $4.5m

Originally posted by waynos


can't you buy a helicopter for less than $4.5m

Yeah you can buy restored 1953 Bell 47 (MASH helicopter) for $159,950
www.bell47g.com...

4-5 million and I think you can start getting those sweet Helicopters CEOs fly around in you got to cruise in style

What about the C-130 Jumpjet?
Did it ever fly or was it just a consept?

I've seen pictures of the C-130 with RATOG equipment, but I've never heard of a C-130 Jump jet.

Do you mean the specially modified Herk that was to be used to rescue the Iranian Embassy Hostage's?. It was designed to land in a football stadium and had forward firing rockets designed to stop it within a very short distance.

I've seen a video somewhere of a practice landing that went wrong because they fired in rockets whilst the Herk was still about ten foot of the Deck!

Needless to say it stopped in mid air and hit the deck so hard it broke up!

The Aircraft was not used for the rescue mission which is another story in itself

Sv Out......!

What about using the engines developed for the F-35 incorporating the lift fan? Maybe a nodified and uprated version of this engine would provide enough thrust and controllability?

Maybe an Osprey fitted with two of these engines instead of the tilt rotors might provide the solution ( copyright pending!!!!!!!!)

Sv Out.......!

Whats the load capacity of the harrier jump-jet?
If the frame of that could be made larger and carrying capacity increased it could work ok. As speed isn't really the issue just access to hard-to-reach locations.

I think the max thrust of current Pegasus engines is about 24,000lbs, that therefore becomes the weight at which VTO is no longer possible, but vertical landings still are, therefore if the aeroplane itself, including fuel and pilot weighs 20,000lb you would have a spare capacity of just under 4,000lb. Of course as you make the plane bigger you also make it heavier and run the risk of it not even being able to lift itself, even empty. To propel an aeroplane vertically upwards from a standing start without the benefit of wing lift requires a massive amount of power and fuel, anyone who has ever witnessed a Harrier at an airshow can appreciate just how much more effort this requires than normal flight. Any half decent capacity transport aircraft is beyond the weight limits of the Pegasus engine unless of course you simply do the maths and fit as many as are required to do the job, however there simply comes a point where any semblence of commercial viability is destroyed by the sheer fuel consumption and complexity of the arrangement. By comparison open blades are far more efficient and as the V-22 shows, enough lift can be generated by a reasonable size and number of engines.


Another attempt to produce a VTOL transport in the very early '70's was this, the Hawker Siddely HS 141. HSA were very serious about launching this aircraft and came close to doing so. A sort of UK answer to the Do 231, but prettier, it used an arrangement of supposedly lightweight lift fans, like that of the F-35B, arranged along each side of the fuselage. The tropuble with transports however, unlike the Harrier, is that the useful load needed makes even this arrangement over complex and uneconomical.