Flightglobal:Rolls-Royce today confirmed that the company’s RTM322 turboshaft engine is the “engine of record” for a new Eurocopter high-speed rotorcraft research program dubbed “X3”...Author: John CroftDate: 23 February 2009Read the full article
Author: John Croft
Date: 23 February 2009
Read the full article
A XXI Century Rotodyne ..... ?
Is this another case of reinventing the wheel or, in this case, the Fairy Rotodyne?
Anyone find the patent or the patent number? Too bad John Croft didn't link that to the article....
There are actually 3 patents (all in French):
RANGE FAST HYBRID HELICOPTER
RANGE FAST HYBRID HELICOPTER AND OPTIMISED LIFT ROTOR
RANGE FAST HYBRID HELICOPTER WITH LONGITUDINAL ATTITUDE CONTROL
The website is a little strange. Don't use the icons. If you want to save, click the link "Save Full Document".
With the X3 looking remarkably like a modernised Fairy Rotodyne the question arises to what powers the rotor. The drawing shown has no anti torque tail rotor which suggests that the rotor is powered, when required, by blade tip jets although these are not shown in the drawing.
The Fairy Rotodyne had a significant noise problem caused by the original single flame tube tip jets. I understand that a solution had been designed which reduced the noise from 113 db to 96 db at 600 ft. I assume that this new tip jet design had been tested and the 96 db noise level had been confirmed but, I believe the project was cancelled before the new tip jets were test flown.
The new tip design was a unit that was made up of 9 x small flame tubes in a one piece combustion chamber with each flame tube exhausting through cold air mixing noise silencing exhaust nozzle. The unit was 4 ft long and no doubt quite slim and light weight to enable them to be fitted into the blade tip without creating unacceptable loadings on the blade.
In the USA, Darpa has sponsored research which is being carried by the Groen brothers but this has stopped due to company financial problems and to the inability to reduce the noise to an acceptable level. Darpa has now transferred that research to Georgia University who have apparantly some expertise in this field. The only picture of results of the Darpa financed research is what appears to be a single piece flame tube and what is possibly an exhaust nozzle, I'm not sure if this is a standalone unit or part of a multi tube unit.
My questions are;
1) Was the original noise reducing units developed during the Rotodyne period ever tested in a ground test stand and if so were they ever tested on the aircraft itself?
2) Are the Darpa financed quiet tip jets a new design or, are they working on a modernised version of the original multi flame tube with air mixing exhaust nozzles?
Oops, I stand corrected
..... The Fairy Rotodyne had a significant noise problem .....
I confirm .....
In 1959, as a very young aviation enthusiast, I attended the Paris Air Show and I can remember vividly the flight demonstration of that strange, but highly promising, hybrid ..... very noisy, indeed .....
One in the long list of many bold British projects cancelled by myopic decisions .....
From what I can ascertain from the patents I think the Eurocopter X-3 works something like this.
In the patents the X-3 is described as a hybrid helicopter. It is not as I first suspected a modernised Fairey Rotodyne utliising rotor blade tip jets to power the rotor but, it is in fact a heliplane that utilises a, no doubt computerised proportional control system, to intergrate the engine powered rotor collective and pitch control system with the propellor pitch control to provide the anti torque required by the engine powered rotor.
To do this I believe that when the heliplane is the forward flight mode the forward thrust is provided by the engine/propellor units with the lift being provided by the wings. The rotor will be autorotating.
When the heliplane transitions to the helicopter mode the power from the engines will be transferred to power the rotor whilst, a proportional control system that intergrates the rotor collective and pitch control system to the propellor pitch control systems will provide the necessary anti torque for the engine powered rotor by balancing the propellor thrust.
If X-3 comes to fruition it should be a very interesting competition between the Sikorsky and Eurocopter to develop a high speed (and heavy lift) helicopter.
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