A tractor Gyro with vertical takeoff and landing.

[Rotor Rooter]

The basis for a small recreational gyrocopter with VTOL ?????

Sud-Ouest SO.1310 "Farfadet"

[PTKay]

Like many other great ideas of the 50-ies killed for unknown reasons.

[brett s]

Looking at the drivetrain complexity & installed power vs payload might be a pretty big clue as to why it went away.

[Rotor Rooter]

True but................

What if;

1. Single engine drives prop and compressor.
2. The tip jets are cold tip.
3. The fuselage contained a carbon filament-wound airtank (high pressure and light weight)
4. The rotor has a fixed pitch of +2 to +4 degrees.
5. The wings are shortened until they can only support a portion of the lift .
6. For takeoff and landing the rotor is spun at a high RPM (consuming much compressed air)
7. For cruise the compressor supplies a little air to the rotor so that it provides partial lift, and some air to replenishing the pressure in the tank.
8. During cruise, only the advancing tip jet(s) provides rotational thrust to the rotor.

Dave

[rfonseca]

There is a car being driven only on compressed air hitting the market soon. This means that the technology has advanced and may be ready for gyro/helicopters.

[Arnie Madsen]

Dave Jackson

Thanks for the link. I thought I knew everything until I came across your post the "Sud-Ouest SO.1310 "Farfadet"from 1953

I love the concept and the idea and the search for high speed rotorcraft and I thank you.

My calculation is 360 hp for the powered rotor and 360 hp for forward prop.

The total is 720 hp to lift off vertical and provide a forward speed of 250 kmh .

It brings me back to the Hughes 500 helicopter and Bell 206 Jetranger using a (derated allison) of 317 hp (and up to rated) 420 hp for vertical takeoff as well as forward speed of 282 kmh (for the Hughes)

So by my calculations , with half the horsepower and powertrain of the Farfadet the Hughes 500 accomplished the same thing. Maybe even better.

For this reason maybe the Farfadet was set aside by the marketplace. Just a guess on my part.

I am well aware of your constant research looking for a high speed rotary wing. I still think it can be done. Much simpler than current research. Keep looking. I understand your thinking.

Thanks again.
Arnie.

[Arnie Madsen]

The SO.1310 is provided with two independent power units. In the rear is an Arrius II 360hp Turbomeca unit, which supplies the jet rotor with compressed air at take-off. The all-metal three-bladed rotor is identical with the one used in the SO.1120 "Ariel III", but with a larger diameter.

In the forepart there is a Turbomeca Artouste II turbo-prop engine with a take-off power of 360hp, operating a variable-pitch airscrew.

Hi Dave , it is Arnie again.

For a moment I wanted to edit my previous post , thinking I made an error. But I do not beleive in editing to cover my asss .

Tell me if you read the above quote and see two 360 hp powerplants on this machine. That is the way I read it anyway.

If I was wrong , please tell me , I would like to know. I will add it to my education.

In summary the "Sud-Ouest SO.1310 "Farfadet"from 1953 uses 360hp X 2 = 720 hp = 250 kmh

The Hughes 369/500 Helicopter uses 317 to 420 shp to reach 282 kph.

Appreciate your opinion or correction Dave,

Thanks Again

I am with you all the way looking for high speed rotorcraft. I appreciate your research and have read most of it.

Arnie.

[karlbamforth]

Lets not forget this was just a project.

Think of it with one engine, 360 Hp will lift it into the hover.
In the hover front engine not needed, then as we translate to forward flight less power is required and it can be used to start to power the prop.

As the aircraft speeds up more power can be transferred to the prop untill there is no power at the rotor and it is in autorotation. We now have 360 Hp at the prop.

Maybe the main reason for fitting 2 engines initially was to keep the systems seperate for testing. That way if an engine fails you can still use the other to return and land.

Maintaining partial power to the rotor would allow for a faster speed.

Just a thought.

[Rotor Rooter]

Arnie, I would agree with your second post and Karl's in that the craft had two engines. The two engines might have been for R&D only, just as the first Sikorsky-ABC had four engines.


Perhaps the craft need not be high speed. Perhaps a lightweight low-cost one could be built. Of the dozens of Tip-Jet threads on Rotary Wing has the compound configuration ever been considered? It might be viable if it has never been considered in the past.

What if the craft used a gimbaled (gyrocopter) rotor head? Perhaps, a significantly reduced tip-jet thrust during cruise would allow for the rotor to have a fixed positive pitch, and, if the engine was to fail then the stored pressure in the tank might assist the craft's 'autorotation' to the ground. There is a NACA report by Pegg that discusses autorotation where the blades have positive pitch.

Here is a portion of a previously received e-mail from a friend in France.
"Tip driven helicopters are inherently inefficient. Best propulsive efficiency is achieved when jet velocity is twice the blade tip velocity, and even though, it is merely 50% (graph attached). This precludes commercial applications, but it would be a good solution for ultralight machines, where endurance is not a paramount."

Excel Graph

If the tip-jet is only to be used for take-off and landing, plus partial use during cruise, it might be viable.

This person has acquired a considerable amount of information on tip-jet rotorcraft over the years. Then, the two of us got interested in electric drives for rotorcraft. If there was to be a renewed and meaningful interest in this configuration on Rotary Wing he may be willing to contribute his knowledge.

Dave

[down under]

A variable pitch prop plus large centrifigal supercharger. The prop is adjusted to neutral pitch and engine run at full rpm. The supercharger will deliver enough air to the tip jets for vertical lift off. Pitch is then applied to the prop to give forward speed. As airspeed increases engine rpm can be dropped thus moving the power from the tip jets to the prop. For very low speed flying the engine revs can be set to deliver a certain amount of power to the tip jets and airspeed controlled by prop pitch adjustments.
Simple and and can easily be built apart from the rotors with air ducting.

[Steve McGowan]

Less my mind is way off,,

Probably is ,, but there's already onea those,,,

Pitcairn I believe is the name.. and it pose to be at Mentone.

and the noise level will get you shut down with the tip jets.. same as the Fairy RotorDyne

[down under]

Numbers one to seven look good. Noise may not be a problem with cold air jets.

Number eight may be a problem. As the compressed air would be pulsing to drive just the advancing blade the blade would need to be a tuned length, as in intake runners on an engine to make it efficient and this would only suit one rpm speed. The runner would need to change length as the rotor changed rpm.

[Rotor Rooter]

down under,

Some thoughts related to your concerns about #8. "As the compressed air would be pulsing to drive just the advancing blade .... tuned length"

My personal feeling is that a propulsor (tip-jet) should not be opposing the forward flight of the craft. Ie. the jet should not be operational when it is on the retreating side.

The maximum thrust of the combined tip-jets is not required during forward flight; due to the wing. A 3-blade rotor might be better. Then the 'gating' of the air flow could be such that each blade delivers its high thrust when it is out to the advancing side (azimuth 90-deg.). Ie. No thrust at the back, (0-deg) increasing to high thrust at 90-deg, then decreasing to no thrust at 180-deg.

I still like the thought of using an air storage tank to help smooth out any pulsations and particularly to provide that 'extra' thrust during take-off out of ground effect and the initial part of the transition into forward flight.


Dave

[down under]

If the compressed air were gated at the hub and the flow is suddenly stopped the velocity of the air and inertia will create a low pressure in the rotor duct. The air will then rebound causing a high pressure. This will be like a spring bouncing with pressure waves traveling up and down the rotor duct. If the rotor rpm is in sync with the pressure waves the out going wave will help draw in compressed air. If it is out of sync the compressed air would be pushing against an in coming pressure wave causing a difference in thrust at different rotor rpm. A gate that opened gradualy and closed gradualy may nullify this.
There may need to be some compressed air to the retreating blade as the unused tip jet would create drag.
I have often wondered how low pressure tip jets affect tip drag and vortices. There may be some advantage in this.

The storage tank may work, its advantage being a lighter compressor Although the amount of air required may rule that out. I have run onto calculations in the past from two different people that an ultralight type two seat would require off memory about one kg of air per second at 45psi. At the time I worked out this would require 2000cfm @ 45psi. When I looked up centrifigal super chargers I found there were several made to this size.

[Rotor Rooter]

down under,

Just some quick thoughts

If the compressed air were gated at the hub and the flow is suddenly stopped the velocity of the air and inertia will create a low pressure in the rotor duct. The air will then rebound causing a high pressure. This will be like a spring bouncing with pressure waves traveling up and down the rotor duct. If the rotor rpm is in sync with the pressure waves the out going wave will help draw in compressed air. If it is out of sync the compressed air would be pushing against an in coming pressure wave causing a difference in thrust at different rotor rpm.

This should not be a problem. The database form 'FORM: Exhaust - Tuned', shown on this web page was used and the frequency was changed from the engine at 6,000 cycles per minute to a rotor at 500 cycles per minute. The tuned length worked out to just over 50 feet.

I have often wondered how low pressure tip jets affect tip drag and vortices. There may be some advantage in this.

Yes. During cruise the drag on the retreating side should help to rotate the rotor and that mean that the compressor can 'top up the tank faster for a helicopter type landing without ground roll. Perhaps the discharge from the tip-jet could even be given a slight CCW swirl and thereby reduce the tip vortex.

Dave