Can the V-22: bring back the Rotodyne!

The problems which have been experienced by the V-22 Osprey are a
reminder of one very successful alternative: the Fairey Rotodyne. See:
http://www.groenbros.com/tech/FaireyRotodyne.htm
This was a large, passenger gyrodyne which had a separate lift rotor
and two turboprops mounted on a short wing. For take-off and landing,
gas from the turboprops was diverted to jets at the tip of the lifting
rotor, providing the thrust to spin it. For level flight, the
turboprops drove conventional propellers with the autorotating rotor
providing about half the lift.

Disadvantages compared with the V-22? Separate systems for vertical
and level flight.

Advantages compared with the V-22? The lift rotor and propellers were
designed to be optimal for their tasks, instead of being a compromise.
The autorotating ability of the big lift rotor provided a safety
margin. And the whole thing was technically simple and trouble-free.
It WORKED - decades ago! Its only really problem was noise from the
tip-jets, but that would be far less of an issue for a military plane
and they were working on that anyway. It was only cancelled due to
political/industrial reasons.

The company whose website contains the info listed above is proposing
developing new gyrodynes by converting ewxisting fixed-wing planes -
notably, the C-130 Hercules! This seems like a much lower-risk
approach than tilt-rotors.

Tony Williams
Military gun and ammunition website: http://www.quarry.nildram.co.uk
Discussion forum at: http://forums.delphiforums.com/autogun/messages/

Tony Williams wrote:

The problems which have been experienced by the V-22 Osprey are a
reminder of one very successful alternative: the Fairey Rotodyne. See:
http://www.groenbros.com/tech/FaireyRotodyne.htm
This was a large, passenger gyrodyne which had a separate lift rotor
and two turboprops mounted on a short wing. For take-off and landing,
gas from the turboprops was diverted to jets at the tip of the lifting
rotor, providing the thrust to spin it. For level flight, the
turboprops drove conventional propellers with the autorotating rotor
providing about half the lift.

Disadvantages compared with the V-22? Separate systems for vertical
and level flight.

Advantages compared with the V-22? The lift rotor and propellers were
designed to be optimal for their tasks, instead of being a compromise.
The autorotating ability of the big lift rotor provided a safety
margin. And the whole thing was technically simple and trouble-free.
It WORKED - decades ago! Its only really problem was noise from the
tip-jets, but that would be far less of an issue for a military plane
and they were working on that anyway.

Noise is rather a large issue for the military, if you're trying to sneak
up on people to prevent them from shooting at you. The V-22 is much
quieter than a helo when in fixed-wing mode, which means the other side
doesn't hear you coming several minutes in advance (on the rare occasions
that a Huey flies around in the area, despite my lousy hearing I can
usually be dressed and outside my house before it comes over).

It was only cancelled due to
political/industrial reasons.

The company whose website contains the info listed above is proposing
developing new gyrodynes by converting ewxisting fixed-wing planes -
notably, the C-130 Hercules! This seems like a much lower-risk
approach than tilt-rotors.

It will be interesting to see if they can get development money,
especially for something like the modified C-130 prototype, what the loss
in payload is and what maneuver restrictions are imposed by the large
rotor (below 1g I could definitely foresee problems). What's clear is
that the military wants their next tactical transport to be either
superstol or V/STOL, combined with roughly C-130 capabilities, so that
they don't have to capture an airfield as was the case with FOB Rhino in
Afghanistan. Conventional helos just aren't going to cut it. Piasecki is
working on compounds again (UH-60 or AH-64 prototype, I forget which)
under a DARPA project, and then Boeing, Bell, Lockheed and everyone else
are looking at the next step beyond the C-130/CH-53E as well as a
potential XC-14/15 type a/c, even if the acronym seems to change monthly.

Guy

(Tony Williams) wrote in message om...
The problems which have been experienced by the V-22 Osprey are a
reminder of one very successful alternative: the Fairey Rotodyne. See:
http://www.groenbros.com/tech/FaireyRotodyne.htm
This was a large, passenger gyrodyne which had a separate lift rotor
and two turboprops mounted on a short wing. For take-off and landing,
gas from the turboprops was diverted to jets at the tip of the lifting
rotor, providing the thrust to spin it. For level flight, the
turboprops drove conventional propellers with the autorotating rotor
providing about half the lift.

Disadvantages compared with the V-22? Separate systems for vertical
and level flight.

Advantages compared with the V-22? The lift rotor and propellers were
designed to be optimal for their tasks, instead of being a compromise.
The autorotating ability of the big lift rotor provided a safety
margin. And the whole thing was technically simple and trouble-free.
It WORKED - decades ago! Its only really problem was noise from the
tip-jets, but that would be far less of an issue for a military plane
and they were working on that anyway. It was only cancelled due to
political/industrial reasons.

The company whose website contains the info listed above is proposing
developing new gyrodynes by converting ewxisting fixed-wing planes -
notably, the C-130 Hercules! This seems like a much lower-risk
approach than tilt-rotors.

Tony Williams
Military gun and ammunition website: http://www.quarry.nildram.co.uk
Discussion forum at: http://forums.delphiforums.com/autogun/messages/



There was an extensive article on this in a recent air international.

These rotadynes essentialy use compressed air from the main engines
to drive tip jets in the rotor. The tip jets, in order to keep the
compressed air requirements low and hover ability high are not cold
tip jets but burn fuel to boost thrust.

The advantages are that no complicated highly stressed mechanical
componenets are required. The stresses are so low that existing air
farmes can be used eg a C130.

The Fariy Rotadyne worked but had 3 problems: two technical and one
political.

One the engines were underpowered and not in production, two the tip
jet noise was enormous (but Fairy engineers thoutht they were about to
crack that problem) and finaly polictical. The British government cut
its development.

Unlike the V22 there were no lethal accidents. Transition from hover
to flight and back again is seemless and requires not complicated and
dangerous change of modes.

In article ,
"Jim Atkins" writes:
Aren't there severe weight problems involved with separate vertical and
horizontal systems? Seems I recall things like Dornier's transport (Do 31?)
with dedicated lift jets that could just barely transport the weight of the
crew.

There are, especially in teh case of lift-jet aircraft, like the
Dornier, which had to haul around a bimnch of engines that were only
used for a short time each flight, but it's not that much of a problem
with something like the Rotodyne, or even the almost-contemporary
Lockheed AH-56. In the case of those aircraft, the rotors still
provide lift, but they're unpowered, acting as an Autogiro fotor, and
a fair chunk of the lift is taken up by the fixed wings. I guess
you'd lose a bit of hover performance becase of the extra wing area
under the rotor, but that would also accur with a tiltrotor.

I suspect that Vmax would not theoretically be as high, you'd still
have to deal with stuff like rotor tip speeds and retreating blade
stall, but it'd be a fair shot.

For the Rotodyne, noise was a severe problem. (Engine selection
wasn't - Fairey wanted to move to teh Tyne for any later developments)
If the newsreel soundtracks of teh thing I've heard are accurate, it
could only be described as that of a Huey carrying a large, running
Steam Locomotive. Consider this - Rotodyne noise was considered
objectionable during a time when acceptable noise included
unsuppressed straight-jet 707s and the just-proposed Concorde. You
gotta go some to beat them.

--
Pete Stickney
A strong conviction that something must be done is the parent of many
bad measures. -- Daniel Webster

"Jim Atkins" wrote in message
et...
Aren't there severe weight problems involved with separate vertical and
horizontal systems? Seems I recall things like Dornier's transport (Do
31?)
with dedicated lift jets that could just barely transport the weight of
the
crew.

--
Jim Atkins
Twentynine Palms CA USA


Yeah but the rotodyne didnt really have separate systems except
for the tipjets

It was a large autogyro but the engines that drove it horizontally
could be tapped for bypass air which when fed to tipjets and burned
allowed it to function as a helicopter.

Its flight tests were succesful and it lifted a respectable load, its
real limitation, as with any helicopter is top speed. Due to the
problems of imbalanced lift between advancing and lagging rotors
it will never match a fixed wing aircraft for speed.

Keith

"Jim Atkins" wrote in message . net...
Aren't there severe weight problems involved with separate vertical and
horizontal systems? Seems I recall things like Dornier's transport (Do 31?)
with dedicated lift jets that could just barely transport the weight of the
crew.

There is a weight penalty, but that would have to be set against the
greater efficiency of a rotor and turboprops which were specialised
for their purpose (the V-22's prop-rotors are too small to be
efficient rotors, too large to be efficient propellers). In any case,
the weight penalty for the Rotodyne is probably at a minimum, as we're
not talking about needing separate engines, just ducting the gas to
the tip-jets. And compared with a fixed-wing plane, the extra rotor
weight is offset to some extent by the need for a smaller wing, and
probably also by the need for less rugged undercarriage.

Tony Williams
Military gun and ammunition website: http://www.quarry.nildram.co.uk
Military gun and ammunition discussion forum:
http://forums.delphiforums.com/autogun/messages/

Guy Alcala wrote in message ...

Noise is rather a large issue for the military, if you're trying to sneak
up on people to prevent them from shooting at you. The V-22 is much
quieter than a helo when in fixed-wing mode, which means the other side
doesn't hear you coming several minutes in advance (on the rare occasions
that a Huey flies around in the area, despite my lousy hearing I can
usually be dressed and outside my house before it comes over).

I'm not sure how much of a problem it would be in this case, as the
noise came from the tip-jets which were only lit up when the Rotodyne
was preparing to land. In level flight the rotor was just
autorotating. I don't know if this would produce any more noise than a
fixed-wing, but I suspect it would be much less than a helo.

Tony Williams
Military gun and ammunition website: http://www.quarry.nildram.co.uk
Military gun and ammunition discussion forum:
http://forums.delphiforums.com/autogun/messages/

On Sun, 10 Aug 2003 22:39:39 -0400, (Peter Stickney)
wrote:

it could only be described as that of a Huey carrying a large, running
Steam Locomotive.

That is almost onomatopoeic in its description ! :-) It wouldnt have needed
m60s going in to a hot LZ. Just run low over the treeline and the poor
buggers underneath collapse with blood running from their ears LOL



greg

--
$ReplyAddress =~ s#\@.*$##; # Delete everything after the '@'
Alley Gator. With those hypnotic big green eyes
Alley Gator. She'll make you 'fraid 'em
She'll chew you up, ain't no lie

In article , Peter Stickney
writes
For the Rotodyne, noise was a severe problem. (Engine selection
wasn't - Fairey wanted to move to teh Tyne for any later developments)
If the newsreel soundtracks of teh thing I've heard are accurate, it
could only be described as that of a Huey carrying a large, running
Steam Locomotive. Consider this - Rotodyne noise was considered
objectionable during a time when acceptable noise included
unsuppressed straight-jet 707s and the just-proposed Concorde. You
gotta go some to beat them.

Wasn't that just because of the 'city' environment it was expected to
operate in. IIRC PanAm wanted something like 50 for city centre to
airport operations?

--
John

In article , Keith Willshaw
writes
Its flight tests were succesful and it lifted a respectable load, its
real limitation, as with any helicopter is top speed. Due to the
problems of imbalanced lift between advancing and lagging rotors
it will never match a fixed wing aircraft for speed.

Didn't it carry a load of passengers to the Paris airshow from London,
can't remember but something like 20-30 people?

During development they kept reducing the wing angle as they found the
rotor continued to provide most of the lift. As they did this, speed
increased, I'm not sure if they got as far as finding the optimum
configuration.

--
John