491 replies to this topic

[bigleagueslider]

Spending a pound,by going for the idea of ineffective VTOL aircraft carriers again,to save a penny in building 'proper' ones.It would be interesting to find out how much was saved by scrapping the Ark Royal and Eagle and their Phantom force v the costs of lost ships during the Falklands War.

But I think the Argies don't have too much to worry about even if they wait until we've built our new frisby carriers and we probably won't be able to rely on Chile's help this time either.Although having said that the new carriers seem to have catapult and arrester capability designed into them which then just leaves the question of what type of 'proper' aircraft would they be supplied with assuming that the government will be clever enough to just use that capability instead and forget about using the F 35.

But the Harrier is no loss considering it's non existent air superiority capabilities.

http://en.wikipedia....ntine_Air_Force

Even with a proper deck and catapult/arrestor systems, the Royal Navy has limited choices for western naval fighters. The Rafael, the F-35C, or the F-18E/F.

As for the Argies gaining air superiority over the "Malvinas", it's not likely. They currently have no carriers, and the only fighters they have with enough range to reach the Falklands are a few older Mirage III's.

It's truly sad how far the once mighty Royal Navy has tumbled. Their sailors are even defenseless against the Iranian navy.

slider

[Wuzak]

Even with a proper deck and catapult/arrestor systems, the Royal Navy has limited choices for western naval fighters. The Rafael, the F-35C, or the F-18E/F.

As for the Argies gaining air superiority over the "Malvinas", it's not likely. They currently have no carriers, and the only fighters they have with enough range to reach the Falklands are a few older Mirage III's.

It's truly sad how far the once mighty Royal Navy has tumbled. Their sailors are even defenseless against the Iranian navy.

slider

The new carriers under cinstruction are to use F-35Cs.

[24gerrard]

By 2020 when these inferior F - 35Cs enter service, they might just as well be placed at Duxford museum with a Wright Flyer.

IMO and the opinion of the many experienced pilots and aviation experts I have talked to, this aircraft is a 'DOG'. the worst compromise and neutering of American 'over kill' ideas ever assembled in one design.

Britain should be getting out of these useless contractual obligations with 'Dream land' and appointing a British design set up to fill the defence gap that this disaster will create.
It needs to be done now.

Edited by 24gerrard, 25 December 2011 - 09:17.

[Vanishing Point]

By 2020 when these inferior F - 35Cs enter service, they might just as well be placed at Duxford museum with a Wright Flyer.

IMO and the opinion of the many experienced pilots and aviation experts I have talked to, this aircraft is a 'DOG'. the worst compromise and neutering of American 'over kill' ideas ever assembled in one design.

Britain should be getting out of these useless contractual obligations with 'Dream land' and appointing a British design set up to fill the defence gap that this disaster will create.
It needs to be done now.

I think the answer is obvious.Bring the production dates forward for the new carriers then ask the US for the drawings for the F 14 and put it back into production here together with the Eurofighter.

[rory57]

Fairey Rotodyne

If nothing else, my discovery via this forum, and exploration of this nearly forgotten aviation byway has been 'quite interesting'.

Cheers, Ozdude

Is this not a wonderful forum? Who could have predicted that the fabulous, forgotten, Fairey Rotodyne could stimulate so much opinion fifty years on
And on a motorsport website! (ok, there has been a fair amount of thread-drift)

[24gerrard]

http://www.edp24.co....ecord_1_1163714

Ken just thought he would yet again show the superiority of his little machines over modern helicopters.
He used to fly in formation with rotodyne at airshows in the 1960's and his W116 is STILL as capable as any rotor winged aircraft in many military and civil tasks and for a fraction the cost.

Never mind, back to bowing to dream land I suppose.

http://www.facebook.com/home.php#!/pho...e=1&theater

[Greg Locock]

Is this not a wonderful forum? Who could have predicted that the fabulous, forgotten, Fairey Rotodyne could stimulate so much opinion fifty years on
And on a motorsport website! (ok, there has been a fair amount of thread-drift)

Disagree. Tweedledum and Tweedledumber are wrecking every thread they are in.

[Tony Matthews]

What Greg says.

[Madras]

So, back to Fairey noise...

[Madras]

The Rotodyne had already reduced its tip noise to 60 db at 100 yards before it was scrapped.
Noise was never a problem, the aircraft was operated a number of times from the heliport in London and there were NO complaints.
The noise issue was used as an excuse to justify selling out one of the greatest aviation technologies of all time.

Hmm, wikipedia has some different noise levels:

There was also a noise-reduction program in process which had managed to reduce the noise level from 113dB to the desired level of 96 dB from 600 ft (180 m) away

What is your source?

[Wuzak]

Hmm, wikipedia has some different noise levels:

There was also a noise-reduction program in process which had managed to reduce the noise level from 113dB to the desired level of 96 dB from 600 ft (180 m) away

How does that compare to an F1 car?

Certainly an F1 car would be over 100dB at the distances you watch them in Melbourne - c.20m.

[ozdude]

I have been searching, so far unsuccessfully for actual aircraft noise measurements from the 60's through to now. If these figures were available, we could make actual comparisions, and probably extrapolate what noise levels a current Fairey Rotodyne would make. Any takers??

[24gerrard]

Sorry cant help anymore, I might disrupt the thread for those that believe they own it.
No wonder the economy is in such a mess with such dead mind sets.

[MatsNorway]

enginee?

Im not a english speaking native but isn`t your signature supposed to say engineer at the end?

[Madras]

Sorry cant help anymore, I might disrupt the thread for those that believe they own it.
No wonder the economy is in such a mess with such dead mind sets.

Are you taking a hissy fit because people are taking a stand against your thread hijacking?

[bigleagueslider]

Here's a good NASA technical reference on some of the issues with the McDonnell XV-1, which was similar in operation to the Fairey Rotodyne. The XV-1 first flew a couple years before the Rotodyne. It's 280 pages, but definitely worth a look.

http://hdl.handle.net/2060/20080022367

Regards,
slider

[24gerrard]

Here's a good NASA technical reference on some of the issues with the McDonnell XV-1, which was similar in operation to the Fairey Rotodyne. The XV-1 first flew a couple years before the Rotodyne. It's 280 pages, but definitely worth a look.

http://hdl.handle.net/2060/20080022367

Regards,
slider

[MatsNorway]

I found a typo.. or is there something called Sherical Bearing ?

Glad im not working with such things.. geeeses there is a lot of formulas.

Edited by MatsNorway, 30 December 2011 - 14:54.

[24gerrard]

I found a typo.. or is there something called Sherical Bearing ?

Glad im not working with such things.. geeeses there is a lot of formulas.

Sadly all the work done in the UK which resulted in a fully operational in service aircraft with fantastic performance was destroyed.
That is unless anyone has anything left over today, our searches over 40 years have turned up nothing on Rotodyne.

The level of engineering and scientific expertise on such a project is at least as high as for space travel development as slider well knows.
I thank him for his efforts bringing such useful documentation to the discusion.
I realise my bias towards the British aviation industry of old and my critic of the American industry but in this case I must admit to
a high level of respect for those involved with the American project.
At the time of course, there was a great deal of co-operation between our countries and I am sure this American team were just as disgusted as the British when Rotodyne was scrapped.

Unfortunately the vast amount of data and math shows just what a task the development of a modern Rotodyne would entail.
This is the reason why I continue to promote Ken Wallis and his light autogyro.
It has the potential for large scale production and would fit many aviation tasks both civil and military and at a very low cost.
It would also create a technical base which could be used to develop much larger autogyro.convertiplanes on the lines of the Rotodyne.

I had considered leaving these forums because of the self serving attitude of some posters but I believe this subject to be more important than my own opinions and motivations.

[Wuzak]

Unfortunately the vast amount of data and math shows just what a task the development of a modern Rotodyne would entail.

What if you forgot about the vertical takeoff system to start with. Could an autogyro the size on a Rotodyne be made with the current knowledge?

If that is too big, what about an attack helicopter size craft, or something about the size of a Blackhawk?


Looking at the XV-1 I could imagine that evolving into an attack helicopter.

[24gerrard]

What if you forgot about the vertical takeoff system to start with. Could an autogyro the size on a Rotodyne be made with the current knowledge?

If that is too big, what about an attack helicopter size craft, or something about the size of a Blackhawk?


Looking at the XV-1 I could imagine that evolving into an attack helicopter.

Good suggestions Wuzak, I think you might be on to something.

Yes it would be much easier to build a pure autogyro without the VTOL capability.
The ability to hover is needed far less for many tasks than at first thought.
With a landing speed of 7 mph the W116 can land verticaly in most windy conditions, 10 feet in still air.
Take off at light load in 15 feet. Take off run depends on loading.
It is not so much the size of the aircraft but the rotor loading than alters the above figures. (of course if it is over 15 feet long haha)

The attack helicopter role does not need the hover capability, in fact more rapid changes in direction and speed are a distinct advantage.
An unloaded rotor can give you this, in fact the Wallis can fly rings around an Apache.
Autogyros also have zero rotor downwash and all the noise is drawn up away from the ground, a military Wallis is silent over 500 feet.
All current gunships are unusable close to the ground in sandy and dusty theaters of operation.
The dust also kills turbine engines, resulting in stupid engine lifes.

The Wallis can fly over sand/dust at 3 feet and 125 mph with NO dust cloud, it can be on target before anyone knows it is there.
Linked in pairs using another Wallis silent and invisible over 5000 feet directing the attack, with almost zero radar and infra red signatures the system is unbeatable for rapid deployement attacks, either from the back of a C130 or strait from the deck of a light military patrol vessel as small as 30 feet (6 can be carried and the trials are completed).

Larger versions are possible but why not use the already proven (in all roles) W116, we can teach a soldier to fly one in 20 minutes and they would cost no more than a police car.

Edited by 24gerrard, 31 December 2011 - 15:26.

[24gerrard]

Looking at the XV-1 I could imagine that evolving into an attack helicopter.

In my opinion the XV-1 had three major failings.

The single pusher engine and small propeller.
The lack of low speed lateral (rudder) control.
The attempt to develop all three flight regimes in one rotor design, helicopter, autogyro and zero angle of attack rigid fixed wing.

The Rotodyne had two engines out on the stub wings.
This cured the very large rotor pylon and rotor head drag of the XV-1 which was created to a large part by the airflow through the airscrew.
It also cured the lateral control problem that forced the XV-1 to be fitted with ineficient tail rotors.
The Rotodyne used variable pitch (and reverse thrust) airscrews to give perfect low and zero speed lateral control.

The XV-1 compares more to the Wallis light autogyro in as far as the propeller comparisons go.
The airframes on both aircraft limit the diameter of the single propellers, which badly restricts the power available for thrust.
In the W116 case this is not a problem because of the aircrafts size (it operates on 90 hp and could use up to 250 with no design problems). Ken Wallis has hand made many of the Wallis propellers and they are of very high efficiency.
There is a Subaru flat 4 Wallis W116 test aircraft that could easily be re-fitted with a group N level rally spec engine reduced to around 200 hp from 250 and using the turbocharger for altitude power stability. The aircraft can easily reach 20,000ft ordinarily aspirated.
The unloaded rotor only needs a slight increase in span to reach very high height records probably well over 30,000ft and way higher than any helicopter.
Reduced in rotor span the aircraft should also be good for well over 200mph on 200 hp).

The XV-1 by comparison, was IMO at its design limit and very underpowered.
I am sure the American team were well aware of this and knew the answers
(basicaly twin engines, which with a four bladed rotor can give full one engined failure control in all flight modes).

As it was the powered rotor lobby got their way and this spilled over into the reasons for the Rotodyne being scrapped.

Edited by 24gerrard, 31 December 2011 - 19:32.

[Bloggsworth]

Disagree. Tweedledum and Tweedledumber are wrecking every thread they are in.

Give them back their rattle, that should sort it...

[bigleagueslider]

As it was the powered rotor lobby got their way and this spilled over into the reasons for the Rotodyne being scrapped.

24gerrard,

Besides the XV-1, there was lots of activity with tip jet powered rotors going on in the early/mid 1950's, both in the US and Europe. In the US, Hiller was probably the most active. In France, Sud-Ouest (Aerospatiale) actually got the Djinn into production.


Hiller


Hiller


Djinn

regards,
slider

[Greg Locock]

And whatever their virtues, noise regs would kill them quick smart in most applications.

I once saw a discussion of power laws in science. The highest exponent anyone had found was 8, it was the relationship between jet velocity and noise generated. That is Noise is proportional to jet velocity to the power of 8.

http://people.bath.a...tml/node34.html

Small jets need high jet velocities to create reasonable thrust. So they are noisy. If you make the jet larger then it'll create more drag when you are cruising.

This seems a much better solution. http://en.wikipedia.org/wiki/Gyrodyne or its jet version if you are wedded to jets. Admittedly you need a powered rotor.

[MatsNorway]

Lets not forget the centrifuge effects. Making the wing needing more material as its not only going to withstand the punishment of lifting the blob below but also having to hold on to the tip jets for dear life.

[24gerrard]

http://www.rfl31.com..._...4&Itemid=28

Modern developments in both turbo fan engines and by-pass fans, the above improvements to tip jet feed systems that give higher reliable rotor tip thrust and reduce noise to acceptable levels, mean that a modern Rotodyne is eminently feasible.

We also have the potential to produce the first all electric autogyros, which might be capable of both speed and altitude rotor winged records.

Edited by 24gerrard, 05 January 2012 - 11:29.

[Greg Locock]

That's right turbofans and high bypass engines are quieter because they use lower velocities and higher mass flow rates, and so for the same thrust they are larger, which is what I said.

Edited by Greg Locock, 06 January 2012 - 08:47.

[MatsNorway]

For a moment that day i thought the engine was in the prop. i wasn`t thinking. Sorry about that..

[bigleagueslider]

Lets not forget the centrifuge effects. Making the wing needing more material as its not only going to withstand the punishment of lifting the blob below but also having to hold on to the tip jets for dear life.

MatsNorway,

Actually, with hinged rotor blades the CF is what keeps them from bending excessively.

The ramjets used for rotor tip-jets work OK in hover. But there is a fundamental problem they encounter when operating at high forward speeds. There is a huge difference in inlet pressures as the engine rotates from the advancing to the retreating position during each rotation.

slider

[MatsNorway]

MatsNorway,

Actually, with hinged rotor blades the CF is what keeps them from bending excessively.

The ramjets used for rotor tip-jets work OK in hover. But there is a fundamental problem they encounter when operating at high forward speeds. There is a huge difference in inlet pressures as the engine rotates from the advancing to the retreating position during each rotation.

slider

oh so there is a engine in there. So its a bit different to the rotodyne that just ducted some air from the main engine compressors?

By going high rpm blades the difference ratio between the blade speed forward/backward to the forward speed of the heli gets more even.

Something like this.
http://www.youtube.c...7ktLXhq88#t=33s

the downside is the bigger CF working the blades... But Carbon fiber i guess would shrink that problem. I would not be surpriced if the rotodynes gains back then has shrinked due to material improvements.

Edited by MatsNorway, 07 January 2012 - 10:00.

[24gerrard]

oh so there is a engine in there. So its a bit different to the rotodyne that just ducted some air from the main engine compressors?

By going high rpm blades the difference ratio between the blade speed forward/backward to the forward speed of the heli gets more even.

Something like this.
http://www.youtube.c...7ktLXhq88#t=33s

the downside is the bigger CF working the blades... But Carbon fiber i guess would shrink that problem. I would not be surpriced if the rotodynes gains back then has shrinked due to material improvements.

Some tip jet development used ram jets and as slider explains there is a major problem with intake airflow because of the trailing leading blade effects.

Rotodyne used clutched 'cold' compressors that were connected to the turboprop engine's output shafts and fed 'cold' air to the tip jets.
Fuel was also fed to the jets where it was ignited. It needed no ram air effect.
Further development of engines and systems in the pipeline for Rotodyne never happened but even with the underpowered engines used it gave a very useful performance.
With modern turbofan design, bypass air can be fed to the tip jets and developments can be undertaken to reduce the fuel needed at the tip jets.
It is possible to drive a rotor solely from the jet exhaust from a jet, turbojet or turbofan engine of course, as the French work with light tip jet helicopters has proven. It is the practicality of this in large tip jet helicopters and convertiplanes that needs further refinement.
With modern engine design a Rotodyne today would no longer need the extra clutched air compressors to operate a tip jet powered rotor for VTOL.
The design would be even simpler and more fail safe.

[24gerrard]

http://www.youtube.c...7ktLXhq88#t=33s

Nice aircraft. 1960's technology enhanced with modern electronics and materials.
It is still a powered (pair) of rotors though.
It achieves its potential from the pusher propeller and fly by-wire modern electronics.
In this case they have moved the propeller to the rear of the tail to reduce the airscrew effects on the rotor pillar and blades hub.
This proves my statement on the drag problems of the XV-1, which were and are large for a powered rotor.
However with a powered rotor, drag problems in the hub area are still there and made worse by the use of two counter rotating rotors.
In the video they state that an anti 'drag' sail is to be tried at the hub between the rotors.
IMO this will not cure the vibration problems and shows again the problems of a powered rotor for high speed cruise flight.
Because it is a powered rotor, you can 'hear' the rotor vibration build up in the pilots voice as speed increases.

An autogyro would much more easily reach these speeds with far far less vibration.
With a decent budget I could even do it with a 'pure' electric very light autogyro.

Edited by 24gerrard, 07 January 2012 - 14:31.

[bigleagueslider]

oh so there is a engine in there. So its a bit different to the rotodyne that just ducted some air from the main engine compressors?

By going high rpm blades the difference ratio between the blade speed forward/backward to the forward speed of the heli gets more even.

the downside is the bigger CF working the blades... But Carbon fiber i guess would shrink that problem. I would not be surpriced if the rotodynes gains back then has shrinked due to material improvements.

As 24gerrard notes, the Rotodyne burned fuel in the tip jets. But during forward flight the main rotor autorotated and slowed in rotation. The Rotodyne's rotor was quite large in diameter, and it had to be hinged. If it was rigid, there's no way the blades could not have been made strong/thin enough with the materials available.

The X2 coaxial compound in the video you linked is an engine driven rigid rotor. However, it uses a two speed transmission the slow the rotor at higher forward speeds.

As for rotor systems that relied purely on compressed air tip jets (no fuel) there was the Djinn, Farfadet, and Dorand:


Farfadet


Djinn rotor


Dorand

slider

[MatsNorway]

I felt like stating that i have completely chanced my mind about having the motors on the Osprey on the ends.

You see its when the V-22 does vertical take off it puts the highest bending force on the inner part of the wing.

In normal flight it gets lift from the whole wing not just the ends. reducing the bending forces. taking the turns or what ever its called in aviation also makes it take less stress on the wing because the motors is not on the main body.

Only downer with having the motors on the ends is that you get crappy body rotational movement abilities. Yaw?

And that long center shaft.

[24gerrard]

I will never fly in an Osprey.
I used to be worried when a Chinook flew over.
I would be more than worried if an Osprey did.

[Wuzak]

I will never fly in an Osprey.

Is anybody asking you to?

I used to be worried when a Chinook flew over.
I would be more than worried if an Osprey did..

Even if the Osprey is operating in fixed wing mode (ie like a normal plane)?

[24gerrard]

'Normal' plane?

[bigleagueslider]

Is anybody asking you to?

Even if the Osprey is operating in fixed wing mode (ie like a normal plane)?

Wuzak,

In some respects, you are safer in the Osprey than you are in a fixed wing aircraft. For example, if it is necessary to make an emergency landing, the VTOL Osprey can do so safely just about anywhere, while the fixed wing aircraft needs a suitable runway.

As for 24gerrard's concerns about being overflown by a V-22, as long as he stays in the UK that's highly unlikely. Not many USMC operations there.

And frankly, 24gerrard's concerns about CH-47s or V-22s dropping out of the sky and landing on him are a bit misplaced. The Royal Navy's Harriers had a much more abysmal safety record than either the CH-47 or V-22. And he apparently had no concerns about the hazard they presented to his personal safety, at least before they were removed from service.

slider

[24gerrard]

[quote]name='bigleagueslider' date='Feb 5 2012, 03:33' post='5508421']
Wuzak,

In some respects, you are safer in the Osprey than you are in a fixed wing aircraft. For example, if it is necessary to make an emergency landing, the VTOL Osprey can do so safely just about anywhere, while the fixed wing aircraft needs a suitable runway.[/quote]

I totally disagree, in fixed wing mode the Osprey has a very high stalling speed. STOL capability is achieved using airflow from its rotor/airscrews and the tilt angles of its wings. If there is a mechanical failure other than a very simple one engined failure (without airscrew compromise), the result is always catastrophic.
I would like to see any pilot tilt the wings from horizontal to fully vertical and change the blade angles on both rotor/airscrews to autorotate before control is lost and the ground found. This assumes that control over both rotor/airscrews is still available.
The Chinook was a little better, although the added mechanical link between the two rotors (same as Osprey) made it more dangerouse by far than a single rotor helicopter.

By comparison the Wallis W116 light autogyro has a rotor with an unlimited fatigue life and it has NO mechanicl drive.
Like the Fairey Rotodyne it is already flying in 'autorotate' and complete dual engine failure (rotodyne) results in a calm controlled decent.
The W116 even has a pilot training task which includes engine off landings.
The Wallis in fact has an engine off sink rate in unloaded form close to a sailplane. so in theory the pilot could thermal away from danger if the engine stopped.

[quote]And frankly, 24gerrard's concerns about CH-47s or V-22s dropping out of the sky and landing on him are a bit misplaced. The Royal Navy's Harriers had a much more abysmal safety record than either the CH-47 or V-22. And he apparently had no concerns about the hazard they presented to his personal safety, at least before they were removed from service.[/quote]

The harrier is a fighter and all fighter pilots are fully aware that any major engine problem will result in the need to eject.
The harrier also operates in two flight domains, so the accident rate can be expected to be higher.
The cost of the JSF even now that the silly VTOL capability has been removed (which would have given it a far higher accident rate than the harrier) will make it the biggest resource wasting disaster Great Britain has yet to stomach from America's obsolete war inventory.
I just hope we will not be so silly as to buy Osprey.

Edited by 24gerrard, 05 February 2012 - 10:30.

[bigleagueslider]

24gerrard,

You mentioned having flown numerous times in a DC-3. In a max GTOW condition, the V-22 is much safer than the DC-3 with loss of 1 engine. The DC-3 would tend to roll over, while the V-22 would not.

slider

[24gerrard]

24gerrard,

You mentioned having flown numerous times in a DC-3. In a max GTOW condition, the V-22 is much safer than the DC-3 with loss of 1 engine. The DC-3 would tend to roll over, while the V-22 would not.

slider

I have been very close to that on a couple of occasions slider but come on, comparing a DC3 with an Osprey.

The only reason the Osprey would not roll over is because of the shaft driving both airscrews from one engine and the far higher power.

The DC3 would 'tend' to roll over at high all up weight but its crash landing speed on one engine would still be lower than an Osprey.

Edit: Of course there is no comparison at all with a Fairey Rotodyne.
With the Rotodyne you could turn off BOTH engines at any altitude and still achieve a flared short landing even at maximum load.

Edited by 24gerrard, 07 February 2012 - 09:19.