Sikorsky X2 coaxial heli developments.
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Regarding the world speed record/compound helicopter debate... I'm gonna go grab me a 777 engine and throw it in a tube frame with 1% of its compressor bleed air turning a main and tail from a R22. The rest will be used as thrust. But since its the same engine as is used to power the rotor system, I'll own the record for rotary winged flight at somewhere around Mach 1. Suck my contrails, X2.
Anyone who has stood behind a turboshaft engine knows there is no way that the Gems on G-LYNX were providing thrust on the same level as the X2 or any of the other compound helicopters out there. Compound helicopters in my opinion are a contraption that uses a rotor system to get up and something else to get going - IE compounding vertical lift with horizontal thrust. The X2 is no better than the 533, and neither of them should be compared to the Lynx. Good job Sikorsky, you revived an old idea that deserved a second chance.
Mike
Anyone who has stood behind a turboshaft engine knows there is no way that the Gems on G-LYNX were providing thrust on the same level as the X2 or any of the other compound helicopters out there. Compound helicopters in my opinion are a contraption that uses a rotor system to get up and something else to get going - IE compounding vertical lift with horizontal thrust. The X2 is no better than the 533, and neither of them should be compared to the Lynx. Good job Sikorsky, you revived an old idea that deserved a second chance.
Mike
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TwinHueyMan:
the point is that the Gems on the Lynx were producing enough thrust to make the difference. Westlands has never come right out and stated how much thrust was produced, nor now they did it (at least, I haven't seen it and I think I keep my ear pretty close to the ground on stuff like this).
But you can be assured it was quite a bit of thrust.
the point is that the Gems on the Lynx were producing enough thrust to make the difference. Westlands has never come right out and stated how much thrust was produced, nor now they did it (at least, I haven't seen it and I think I keep my ear pretty close to the ground on stuff like this).
But you can be assured it was quite a bit of thrust.
The whole idea behind a turboshaft is to suck every last ounce of power out of the airflow, power is sent to the gearbox, and the airflow just trickles out the exhaust.
If that Gem was producing thrust, it was because some dude altered it to make it do so, otherwise it must have been a seriously inefficient engine. usually there is only about 10lb of thrust at the exhaust.
If that Gem was producing thrust, it was because some dude altered it to make it do so, otherwise it must have been a seriously inefficient engine. usually there is only about 10lb of thrust at the exhaust.
Not so A C.
In a perfect world, yes all the energy in the gas stream would be absorbed by the turbines, but this assumes 100% (or close to) efficiency and in a gas turbine engine (even a modern design), this is simply not the case.
For example, on the Pratt & Whitney Canada PT6A-65AR, the pressure (PSIA) of the gas stream at station P7 (Exhaust Duct Outlet) at take-off power is some 9% to 10% higher than at station P1 (Inlet) and as it’s ejecting around 9lbs in weight of air per second at max power, that an awful lot of gas flow to use for thrust should you wish to point it in a rearwards direction.
In my Chinook days, I was once told that around 5% of the energy in the gas stream was ejected rearwards out of the exhaust as thrust, and that’s without tweaking, so certainly not insignificant.
Those 'Pasty Boyz'
played around with the exhaust for a reason and it wasn’t for looks.
In a perfect world, yes all the energy in the gas stream would be absorbed by the turbines, but this assumes 100% (or close to) efficiency and in a gas turbine engine (even a modern design), this is simply not the case.
For example, on the Pratt & Whitney Canada PT6A-65AR, the pressure (PSIA) of the gas stream at station P7 (Exhaust Duct Outlet) at take-off power is some 9% to 10% higher than at station P1 (Inlet) and as it’s ejecting around 9lbs in weight of air per second at max power, that an awful lot of gas flow to use for thrust should you wish to point it in a rearwards direction.
In my Chinook days, I was once told that around 5% of the energy in the gas stream was ejected rearwards out of the exhaust as thrust, and that’s without tweaking, so certainly not insignificant.
Those 'Pasty Boyz'
played around with the exhaust for a reason and it wasn’t for looks.
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If they did indeed create such a significant amount of thrust out of the exhaust, why is this not a technology that was explored as a mainstream solution? Bell went to all the trouble to get a couple degrees of aft tilt on the 429s tail rotor to throw in a few pounds of thrust but Westland abandoned their turbojet turboshaft idea when it single handedly produced enough thrust to (according to pprune'rs) push a 160 knot helicopter into the 200+ category?
Mike
Mike
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Don't forget that an integral part of the Lynx's ability to set that speed record with out any fixed lifting surfaces were the BERP rotor blades, not just the jet thrust.
Ascend Charlie, yes you are correct. The exhaust nozzles were modified to a smaller area to produce the thrust.
TwinHueyMan, it looks like they were considering using this in production, not sure why they haven't.
Lynx ACH - Proposed Advanced Compound Helicopter technology demonstrator, partly funded by the Ministry of Defence. Announced in May 1998, the ACH was planned to be powered by RTM322 engines with variable area exhaust nozzles and a gearbox from the Westland 30-200, have wings attached at cabin roof level and BERP rotor blades. It was predicted to fly approximately 50% faster than a standard Lynx.
Ascend Charlie, yes you are correct. The exhaust nozzles were modified to a smaller area to produce the thrust.
TwinHueyMan, it looks like they were considering using this in production, not sure why they haven't.
Lynx ACH - Proposed Advanced Compound Helicopter technology demonstrator, partly funded by the Ministry of Defence. Announced in May 1998, the ACH was planned to be powered by RTM322 engines with variable area exhaust nozzles and a gearbox from the Westland 30-200, have wings attached at cabin roof level and BERP rotor blades. It was predicted to fly approximately 50% faster than a standard Lynx.
Sorry Shawn butv the residual thrust from the Lynx has been well publicised,even on this thread if you go back far enough. It certainly didnt contribute much,it was the blade design that made the speed possible and controllable over the distance required.
Was just sent this video link. I don't think it has been posted here but the thread has been quiet for a while.
-- IFMU
Edit: never mind, it looks just like the youtube one I posted. Tough getting old.
-- IFMU
Edit: never mind, it looks just like the youtube one I posted. Tough getting old.
Last edited by Senior Pilot; 25th Feb 2011 at 10:17.
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Still an excellent video IFMU.
I suspect X2 will go a little quiet while S-97 goes through design & development.
Actually, I have suggested the Sikorsky/Schweitzer design/analysis/test engineers attend some low key engineering lectures - say I.Mech.E or RAES. The need for commercial secrecy may make this unfeasible though. Pity.
I suspect X2 will go a little quiet while S-97 goes through design & development.
Actually, I have suggested the Sikorsky/Schweitzer design/analysis/test engineers attend some low key engineering lectures - say I.Mech.E or RAES. The need for commercial secrecy may make this unfeasible though. Pity.
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Did the X2 do a full touchdown autorotation?
The X2 blade profile and its interaction with the stall, driving and driven regions of the rotor disk are of technical interest.
Thanks
Dave
The X2 blade profile and its interaction with the stall, driving and driven regions of the rotor disk are of technical interest.
Thanks
Dave
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Never a doubt in my mind that this day would come.
Serious congratulations to all involved: managers, designers, analysts, testers, and pilot
This about sums it up:
Collier Trophy - Wikipedia, the free encyclopedia
Just goes to show how a carefully scheduled test program can overcome all the criticism of those ne'er sayers.
Serious congratulations to all involved: managers, designers, analysts, testers, and pilot
This about sums it up:
The Collier Trophy is an annual aviation award administered by the U.S. National Aeronautics Association (NAA), presented to those who have made "the greatest achievement in aeronautics or astronautics in America, with respect to improving the performance, efficiency, and safety of air or space vehicles, the value of which has been thoroughly demonstrated by actual use during the preceding year."
Just goes to show how a carefully scheduled test program can overcome all the criticism of those ne'er sayers.
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Quantity or Quality
The Collier Trophy is an annual aviation award
nimby,
I would take that to mean that they actually flew it, as opposed to generating a large quantity of work of some quality that is contained wholly on the internet. I take it from your post that maybe it means less because the X2 is a one-off machine, not put into production, and focused on a single goal. This is the same category as Rutan and Space Ship One (2004), or the Rutan Voyager team (1986), or Chuck Yeager (1947). I thought about throwing in the crew of Apollo 11 too, but in fairness they did build more than one spaceship.
-- IFMU
I would take that to mean that they actually flew it, as opposed to generating a large quantity of work of some quality that is contained wholly on the internet. I take it from your post that maybe it means less because the X2 is a one-off machine, not put into production, and focused on a single goal. This is the same category as Rutan and Space Ship One (2004), or the Rutan Voyager team (1986), or Chuck Yeager (1947). I thought about throwing in the crew of Apollo 11 too, but in fairness they did build more than one spaceship.
-- IFMU
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"The Royal Aeronautical Society Presents “The Future of Rotorcraft – Enabling Capability through the Application of Technology”
The performance and utility of the ubiquitous edge wise rotary wing configured aircraft has reached a natural limit. The enormous strides taken by the fixed wing community in the development of increasingly efficient, mission focused, cost effective, green and quick to market solutions have not been matched by the rotary wing community. The barrier to matching the fixed wing community is not concepts or vision, it is the infrastructure of technology and manufacturing techniques that have contrived to hold our community back. Learning lessons from the fixed wing community and adapting them to meet the needs of the rotary wing vehicle is our challenge and the time is right now to take on this challenge and succeed. This two day conference will take place June 15-16, 2011 at the Royal Aeronautical Society, No. 4 Hamilton Place, London."
Additional information on this subject;
'The Cost of High Speed' by R.W. Prouty in the American Helicopter Society's publication Vertiflite ~ Spring 2011.
The performance and utility of the ubiquitous edge wise rotary wing configured aircraft has reached a natural limit. The enormous strides taken by the fixed wing community in the development of increasingly efficient, mission focused, cost effective, green and quick to market solutions have not been matched by the rotary wing community. The barrier to matching the fixed wing community is not concepts or vision, it is the infrastructure of technology and manufacturing techniques that have contrived to hold our community back. Learning lessons from the fixed wing community and adapting them to meet the needs of the rotary wing vehicle is our challenge and the time is right now to take on this challenge and succeed. This two day conference will take place June 15-16, 2011 at the Royal Aeronautical Society, No. 4 Hamilton Place, London."
Additional information on this subject;
'The Cost of High Speed' by R.W. Prouty in the American Helicopter Society's publication Vertiflite ~ Spring 2011.
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Mart,
This appears to be the program for the conference.
The Future Rotorcraft ~ Enabling capability through the application of technology
If you do go, it would be appreciated if you could give a synopsis of any presentations of interest, on this thread or a new separate thread.
Dave
This appears to be the program for the conference.
The Future Rotorcraft ~ Enabling capability through the application of technology
If you do go, it would be appreciated if you could give a synopsis of any presentations of interest, on this thread or a new separate thread.
Dave
Collier Video
Hello everyone,
I've got a question about the possible future variants for the X2 technology:
Does anybody know if any of these possible variants (except for the UAV, of course!) are planned to have a pressurised cabin?
Thanks
I've got a question about the possible future variants for the X2 technology:
Does anybody know if any of these possible variants (except for the UAV, of course!) are planned to have a pressurised cabin?
Thanks
