Super-Heavy Lift Coaxial Helicopter
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Super-Heavy Lift Coaxial Helicopter
Sikorsky Awarded Design Analysis Contracts for X2 Technology(TM)
Tuesday September 20, 3:01 pm ET
STRATFORD, Conn., Sept. 20 /PRNewswire-FirstCall/ -- Sikorsky Aircraft has been awarded two US government contracts to perform conceptual, preliminary design for two X2 Technology(TM) heavy-lift coaxial rotorcraft.
The Concept Design and Analysis (CDA) awards from the U.S. Army's Applied Aviation Technology Directorate (AATD) are in direct support of evaluating joint requirements and Joint Heavy Lift (JHL) rotorcraft for the armed forces.
"Sikorsky is very excited about our two X2 Technology Joint Heavy Lift awards. We see this as a real opportunity to show the versatility of a new generation of coaxial rotor technology. We are looking forward to supporting the joint requirements process with two credible concepts that offer unique capabilities to the future force," said Carey Bond, vice president of corporate strategy for Sikorsky.
Sikorsky's efforts will focus on applying coaxial rotor X2 Technology to a super heavy-lift coaxial rotor crane that can cruise at 165 knots and a high- speed super heavy lift configuration capable of cruising at 245 knots.
In June, Sikorsky Aircraft announced plans to build and test a demonstrator for a new class of coaxial X2 Technology helicopters that maintain or improve on the vertical flight capabilities of helicopters and whose high-speed configuration will cruise at 250 knots.
X2 Technology refers to a suite of technologies Sikorsky will apply to achieve new levels of performance in coaxial helicopters. The X2 Technology Demonstrator is funded by Sikorsky Aircraft with development taking place in collaboration with its Schweizer Aircraft subsidiary.
X2 Technology aircraft will hover, land vertically, maneuver at low speeds, and transition seamlessly from hover to forward flight like a helicopter. In a high-speed configuration, one or more 'pusher props' are part of an integrated auxiliary propulsion system to enable high speed with no need to physically reconfigure the aircraft in flight.
AATD describes the CDA activity as defining the "art of the possible, the science of the probable and the design of the affordable" JHL vertical take- off and landing rotorcraft that enables future joint concepts of operations. The CDA will set the technical foundation for joint requirement analysis leading to design concept and performance projections that can reach Technology Readiness Level 6 by 2012.
The AATD contracts call for the conceptual and preliminary design of a baseline aircraft with a 250 nm radius along with eight variations to identify the impact of changes in payload, range, environmental conditions, and shipboard compatibility on aircraft size, performance, operational suitability, cost, schedule, and development risk.
Sikorsky Aircraft Corporation, based in Stratford, Conn., is a world leader in helicopter design, manufacturing and service. Sikorsky is a subsidiary of United Technologies Corporation (NYSE: UTX - News), of Hartford, Conn., which provides a broad range of high-technology products and support services to the aerospace and building systems industries.
Tuesday September 20, 3:01 pm ET
STRATFORD, Conn., Sept. 20 /PRNewswire-FirstCall/ -- Sikorsky Aircraft has been awarded two US government contracts to perform conceptual, preliminary design for two X2 Technology(TM) heavy-lift coaxial rotorcraft.
The Concept Design and Analysis (CDA) awards from the U.S. Army's Applied Aviation Technology Directorate (AATD) are in direct support of evaluating joint requirements and Joint Heavy Lift (JHL) rotorcraft for the armed forces.
"Sikorsky is very excited about our two X2 Technology Joint Heavy Lift awards. We see this as a real opportunity to show the versatility of a new generation of coaxial rotor technology. We are looking forward to supporting the joint requirements process with two credible concepts that offer unique capabilities to the future force," said Carey Bond, vice president of corporate strategy for Sikorsky.
Sikorsky's efforts will focus on applying coaxial rotor X2 Technology to a super heavy-lift coaxial rotor crane that can cruise at 165 knots and a high- speed super heavy lift configuration capable of cruising at 245 knots.
In June, Sikorsky Aircraft announced plans to build and test a demonstrator for a new class of coaxial X2 Technology helicopters that maintain or improve on the vertical flight capabilities of helicopters and whose high-speed configuration will cruise at 250 knots.
X2 Technology refers to a suite of technologies Sikorsky will apply to achieve new levels of performance in coaxial helicopters. The X2 Technology Demonstrator is funded by Sikorsky Aircraft with development taking place in collaboration with its Schweizer Aircraft subsidiary.
X2 Technology aircraft will hover, land vertically, maneuver at low speeds, and transition seamlessly from hover to forward flight like a helicopter. In a high-speed configuration, one or more 'pusher props' are part of an integrated auxiliary propulsion system to enable high speed with no need to physically reconfigure the aircraft in flight.
AATD describes the CDA activity as defining the "art of the possible, the science of the probable and the design of the affordable" JHL vertical take- off and landing rotorcraft that enables future joint concepts of operations. The CDA will set the technical foundation for joint requirement analysis leading to design concept and performance projections that can reach Technology Readiness Level 6 by 2012.
The AATD contracts call for the conceptual and preliminary design of a baseline aircraft with a 250 nm radius along with eight variations to identify the impact of changes in payload, range, environmental conditions, and shipboard compatibility on aircraft size, performance, operational suitability, cost, schedule, and development risk.
Sikorsky Aircraft Corporation, based in Stratford, Conn., is a world leader in helicopter design, manufacturing and service. Sikorsky is a subsidiary of United Technologies Corporation (NYSE: UTX - News), of Hartford, Conn., which provides a broad range of high-technology products and support services to the aerospace and building systems industries.
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It seems after the Commanche fiasco (wheres the threat) that Uncle Sugar would sit back a bit and smell the roses. There has to come a time where is it really necessary to haul more? Cant two or three Chinooks etc do a job with existing technology.
In the face of more urgent things here that require tons of money, I dont really see the need, maybe someone will get me up to speed real soon........... (Im not a big NASA fan either)
Fill us in Nick..........
In the face of more urgent things here that require tons of money, I dont really see the need, maybe someone will get me up to speed real soon........... (Im not a big NASA fan either)
Fill us in Nick..........
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Joint Heavy Lift, (JHL)
The US Army Aviation Applied Technology Directorate, in cooperation with its Joint Service and NASA partners, has awarded five 18-month Concept Design and Analysis (CDA) contracts for a Vertical Takeoff and Landing (VTOL) Joint Heavy Lift, (JHL) rotorcraft. In order of their design cruise speeds, the five concept vehicles chosen for study are the:
[list=a][*] Sikorsky X2C, X2 Technology Crane coaxial rotor (165 knots) [*] Boeing ATRH, Advanced Tandem Rotor Helicopter (165 knots) [*] Sikorsky X2HSL, X2 Technology High Speed Lifter advancing blade compound helicopter (245 knots) [*] Bell Boeing QTR Quad Tilt Rotor (275 knots) [*] Frontier Aircraft OSTR Optimum Speed Tilt Rotor (310 knots). [/list=a]
And, taking the competition to a higher level;
. . f. The Canadian Heavy Lift Joint concept (lots & lots)
Ladies and gentlemen place your bets.
[list=a][*] Sikorsky X2C, X2 Technology Crane coaxial rotor (165 knots) [*] Boeing ATRH, Advanced Tandem Rotor Helicopter (165 knots) [*] Sikorsky X2HSL, X2 Technology High Speed Lifter advancing blade compound helicopter (245 knots) [*] Bell Boeing QTR Quad Tilt Rotor (275 knots) [*] Frontier Aircraft OSTR Optimum Speed Tilt Rotor (310 knots). [/list=a]
And, taking the competition to a higher level;
. . f. The Canadian Heavy Lift Joint concept (lots & lots)
Ladies and gentlemen place your bets.
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That was good Dave and B.C. is notorious for the best smoke.........
In all seriousness, this government pisses away more money by accident than they do on purpose. Go out and but a few MI-26 aircraft and forget this .....
In all seriousness, this government pisses away more money by accident than they do on purpose. Go out and but a few MI-26 aircraft and forget this .....
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Is it possible to build such a huge co-axial system without the danger of a blade collision?
What will be the rotor diameter?
35m or 40m?
What will be the rotor diameter?
35m or 40m?
Last edited by hotzenplotz; 24th Sep 2005 at 00:57.
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Interesting thread...
Regardless of any supposed military application, i see the development of such technology only as a good thing. The likely commercial spin-off in the private sector will be faster more efficient rotorcraft - that has to be good. With another hurricane inbound to the gulf, a potentially faster SAR machine or the ability to deliver supplies point to point is a good thing. V22 may not have the performance to suit all requirements, but it has undeniably opened the door to new rotorcraft potential.
Well directed research always benefits the economy, since the engineers have to eat, drive cars etc. Besides, new start-ups usually result from the design techniques developed. The most immediate NASA spin off of the 60s space race is, after all, the computer i typed this on. Was (for example) Concorde a white elephant? As the basis for the latest russian mach 1.8 bizz-jets, i would argue not in the long run.
One thing i do not understand. Is coaxial genuinely capable of smooth transition from hover to high speed? Without HHC or other, i don't understand how the lower rotor can be optimised for all the upper rotor downwash velocity fields.
Mart
Well directed research always benefits the economy, since the engineers have to eat, drive cars etc. Besides, new start-ups usually result from the design techniques developed. The most immediate NASA spin off of the 60s space race is, after all, the computer i typed this on. Was (for example) Concorde a white elephant? As the basis for the latest russian mach 1.8 bizz-jets, i would argue not in the long run.
One thing i do not understand. Is coaxial genuinely capable of smooth transition from hover to high speed? Without HHC or other, i don't understand how the lower rotor can be optimised for all the upper rotor downwash velocity fields.
Mart
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Graviman. Better check out the russians again. Seems one of the best Gun platorms in the world (Kamov KA-50)is exactly what we are talking about here. Its not new technology, just a bit bigger.........
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Graviman,
Most people will agree that research and product development is a good think, assuming that there is a reasonable chance of success. Regrettably, IMHO the rotorcraft industry has shown little return for the R&D investments.
If interested, read patent US 6,641,365 for Optimum Speed Tilt Rotor at US Patent Search. Your hour long read and comments may say more about the viability of this idea than a multi-million dollar grant and sales presentation will.
If you're in a rush, read; http://www.frontieraircraft.com and; http://www.recce.com/
Most people will agree that research and product development is a good think, assuming that there is a reasonable chance of success. Regrettably, IMHO the rotorcraft industry has shown little return for the R&D investments.
If interested, read patent US 6,641,365 for Optimum Speed Tilt Rotor at US Patent Search. Your hour long read and comments may say more about the viability of this idea than a multi-million dollar grant and sales presentation will.
If you're in a rush, read; http://www.frontieraircraft.com and; http://www.recce.com/
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"If interested, read patent US 6,641,365 for Optimum Speed Tilt Rotor"
Long and tedious read, especially since it looks like frontieraircraft seems to have suffered from that low return...
They didn't really say all that much about the rotor contruction, other than it being epoxy carbon fibre and rigid rooted, but vRRPM is definately the way to go - for tiltrotors too by the looks of things. Using a carefully designed rotor planform/twist makes complete sense, and i'm not suprised they managed to take weight out over a constant chord design. It does show the future potential of the tiltrotor concept.
Did they ever demonstrate the technology? There were a lot of graphs, but these seemed more the result of the CFD study.
Mart
Long and tedious read, especially since it looks like frontieraircraft seems to have suffered from that low return...
They didn't really say all that much about the rotor contruction, other than it being epoxy carbon fibre and rigid rooted, but vRRPM is definately the way to go - for tiltrotors too by the looks of things. Using a carefully designed rotor planform/twist makes complete sense, and i'm not suprised they managed to take weight out over a constant chord design. It does show the future potential of the tiltrotor concept.
Did they ever demonstrate the technology? There were a lot of graphs, but these seemed more the result of the CFD study.
Mart
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B. Sousa,
"Its not new technology, just a bit bigger........."
Not really. The limits of speed for all helos is retreating blade stall. For most single rotors, the stall is a brick wall because they lose control when the retreating blade gives up the ghost. Coaxials get a bit faster because there is an up sweeping blade on each side, but when the down sweeping blades finally stall all the way, they flap wildly, and tend to clash with the other blade going in the opposite direction. Makes a noise complaint, to say the least.
The Sikorsky ABC and the X2 have highly rigid systems (about twice as stiff as BO-105!) so those blades stay in track even when stalled. This means that the rotors can be driven way past "normal" speeds. I have personally flown the ABC at 230 knots and it was a blast. Also, the rigid blades allow the two heads to get closer, reducing the drag quite a bit. Look at how separate the rotors are from each other on the KA-50 vice the X2 designs.
The KA-50 rotor is coaxial, for sure, but the top rotor has only 2% hinge offset, which makes it a soft, floppy rotor. There are rumors that at least two KA-50's have destroyed themselves and their crews in self-midairs.
These new Sikorskys are NOT the same technology at all. Keep your eye on them, I think they could be an answer to dave Jackson's dream, albeit without that intermeshing stuff!
Dave,
That patent is right up there with the Lord's Prayer on a Bar of Soap. All he did was increase the rotor diameter by 100% to raise the hover payload. He forgot to increase the size of the wing, and to study the elastic effects of this "small" change on the rest of the aircraft. BTW, look at the Ct/Sigma vs Mu he shows. For the ABC, max Ct/Sigma demonstrated was .30!! The ABC has nearly twice the maneuver capability of the best helo ever measured.
"Its not new technology, just a bit bigger........."
Not really. The limits of speed for all helos is retreating blade stall. For most single rotors, the stall is a brick wall because they lose control when the retreating blade gives up the ghost. Coaxials get a bit faster because there is an up sweeping blade on each side, but when the down sweeping blades finally stall all the way, they flap wildly, and tend to clash with the other blade going in the opposite direction. Makes a noise complaint, to say the least.
The Sikorsky ABC and the X2 have highly rigid systems (about twice as stiff as BO-105!) so those blades stay in track even when stalled. This means that the rotors can be driven way past "normal" speeds. I have personally flown the ABC at 230 knots and it was a blast. Also, the rigid blades allow the two heads to get closer, reducing the drag quite a bit. Look at how separate the rotors are from each other on the KA-50 vice the X2 designs.
The KA-50 rotor is coaxial, for sure, but the top rotor has only 2% hinge offset, which makes it a soft, floppy rotor. There are rumors that at least two KA-50's have destroyed themselves and their crews in self-midairs.
These new Sikorskys are NOT the same technology at all. Keep your eye on them, I think they could be an answer to dave Jackson's dream, albeit without that intermeshing stuff!
Dave,
That patent is right up there with the Lord's Prayer on a Bar of Soap. All he did was increase the rotor diameter by 100% to raise the hover payload. He forgot to increase the size of the wing, and to study the elastic effects of this "small" change on the rest of the aircraft. BTW, look at the Ct/Sigma vs Mu he shows. For the ABC, max Ct/Sigma demonstrated was .30!! The ABC has nearly twice the maneuver capability of the best helo ever measured.
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Nick,
As a sidebar to your comments;
The above patent US 6,641,365 and his previous patent US 6,007,298 are extremely similar. The principal difference is that the former patent is entitled 'Optimum speed rotor', whereas the latter patent is entitled 'Optimum speed tilt rotor'.
I agree. IMHO, his concept is impractical for hover and impossible for high-speed cruise.
That's the good news.
The bad news is that posting will never be as much fun, if we start agreeing.
Dave
As a sidebar to your comments;
The above patent US 6,641,365 and his previous patent US 6,007,298 are extremely similar. The principal difference is that the former patent is entitled 'Optimum speed rotor', whereas the latter patent is entitled 'Optimum speed tilt rotor'.
I agree. IMHO, his concept is impractical for hover and impossible for high-speed cruise.
That's the good news.
The bad news is that posting will never be as much fun, if we start agreeing.
Dave
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"...concept is impractical for hover and impossible for high-speed cruise."
Dave, you've lost me - why do you draw this conclusion? Agreed that a single rotor twist cannot be optimised for the full mission profile, but i understood that the design was simply to reduce the mass of a larger diameter rotor. This planform design could also be subject to active blade twist, with the right design approach.
One thing i have also never understood is why rotor tip rings have had such a limited appeal. For tail rotor this leads logically to fenestron, so better to start there. For main rotor the tips would need little structural mass (other than hoop stress) and would allow a 14% improvement in figure of merit. Basically the ring forces all the tip vortices to join up, the inflow being pulled in from a 30% larger diameter. Forward flight would equally benefit. What am i not seeing?
Mart
Dave, you've lost me - why do you draw this conclusion? Agreed that a single rotor twist cannot be optimised for the full mission profile, but i understood that the design was simply to reduce the mass of a larger diameter rotor. This planform design could also be subject to active blade twist, with the right design approach.
One thing i have also never understood is why rotor tip rings have had such a limited appeal. For tail rotor this leads logically to fenestron, so better to start there. For main rotor the tips would need little structural mass (other than hoop stress) and would allow a 14% improvement in figure of merit. Basically the ring forces all the tip vortices to join up, the inflow being pulled in from a 30% larger diameter. Forward flight would equally benefit. What am i not seeing?
Mart
Last edited by Graviman; 25th Sep 2005 at 17:30.
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Mart, The tip ring for the rotor is totally impractical, for many reasons, including drag, weight, structural concerns, sizing to accommodate flapping, and perhaps 20 more I left out. These quicly consume the "advantage" of a performance improvement. The anhedral tip is perhaps the only artifact of a tip loss prevention method that has stood up to practical considerations, and it took quite a bit of structural work to make it stay on.
The next nearest concept to a tip ring is Moller's shrouds, which make his tiny rotors seem to be a bit larger, so he gets chuckles from aerodynamicists instead of laughing.
The next nearest concept to a tip ring is Moller's shrouds, which make his tiny rotors seem to be a bit larger, so he gets chuckles from aerodynamicists instead of laughing.
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Graviman,
Hover:
A large diameter does result in a low disk loading. Carbon blades do provide a good strength-to-weight ratio. A slow speed rotor does allow the blades to operate at an angle of attack that is near the optimum L/D ratio. In fact, the earlier of the above two patents may have been applied to Frontier's [Boeing's] A-160 Hummingbird. It is a UAV single rotor helicopter that is intended to have loitering endurance.
Frontier's currently proposal would be ideal for hover if it was a simple side-by-side configuration, however it is a side-by-side that is marginalized by the tilt-rotor features.
High-speed cruise:
It is stated that this proposed craft has the highest forward velocity of the 5 contenders (310 knots). To achieve any semblance of fast cruise the above attributes of hover must be severely inhibited.
0 knots or 310 knots; take your choice. IMHO, this tilt-rotor ain't going to give customer satisfaction in both.
_______________________
As I recall, Boeing's initial proposal for Joint Heavy Lift (JHL) was a Side-by-Side helicopter.
Boeing is leaning toward the lateral Side-by-Side twin-rotor configuration.
Sikorsky is leaning toward the vertical Coaxial twin-rotor configuration.
The high ground in the middle is for Intermeshing and Interleaving twin-rotor configurations.
Hover:
A large diameter does result in a low disk loading. Carbon blades do provide a good strength-to-weight ratio. A slow speed rotor does allow the blades to operate at an angle of attack that is near the optimum L/D ratio. In fact, the earlier of the above two patents may have been applied to Frontier's [Boeing's] A-160 Hummingbird. It is a UAV single rotor helicopter that is intended to have loitering endurance.
Frontier's currently proposal would be ideal for hover if it was a simple side-by-side configuration, however it is a side-by-side that is marginalized by the tilt-rotor features.
High-speed cruise:
It is stated that this proposed craft has the highest forward velocity of the 5 contenders (310 knots). To achieve any semblance of fast cruise the above attributes of hover must be severely inhibited.
0 knots or 310 knots; take your choice. IMHO, this tilt-rotor ain't going to give customer satisfaction in both.
_______________________
As I recall, Boeing's initial proposal for Joint Heavy Lift (JHL) was a Side-by-Side helicopter.
Boeing is leaning toward the lateral Side-by-Side twin-rotor configuration.
Sikorsky is leaning toward the vertical Coaxial twin-rotor configuration.
The high ground in the middle is for Intermeshing and Interleaving twin-rotor configurations.
Last edited by Dave_Jackson; 26th Sep 2005 at 04:54.
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hotzenplotz,
Haven't seen any publicly-released images yet, but I think the general idea is that the tiltrotor will use a speed-adjustable hingeless rigid rotor system similar to that on the A160 Hummingbird VTUAV.
I/C
Haven't seen any publicly-released images yet, but I think the general idea is that the tiltrotor will use a speed-adjustable hingeless rigid rotor system similar to that on the A160 Hummingbird VTUAV.
I/C
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"The tip ring for the rotor is totally impractical, for many reasons, including drag, weight, structural concerns, sizing to accommodate flapping, and perhaps 20 more I left out..."
Nick, Good point well made. I was really wondering whether for a rigid rotor, such as will be used in the coaxial, a "bit of string" around the tips would improve figure of merit. The "bit of string" would be say a light flexible composite tube, with proportions chosen for minimum mass/unit_length for a given ability to trap the tip vortices. Only tensile strength/stiffness would really be required, assuming low RRPM droop did not cause interference in say a 3 or 4 bladed rotor.
The point about drag is well heeded. I did wonder about the magnus affect, but of course this only works in the forward portions (posibly causing unwanted ring distorsion). The tube would possibly need torsional stiffness for a specific aero sections. Keeping mass down thus becomes harder. It's just that other than Bell trying this on a 2-blade tail rotor, i was not aware of any main rotor studies.
----
"Frontier's currently proposal would be ideal for hover if it was a simple side-by-side configuration, however it is a side-by-side that is marginalized by the tilt-rotor features."
Which features are you refering to here, Dave?
"To achieve any semblance of fast cruise the above attributes of hover must be severely inhibited."
Agreed, that fixed twist will not be ideal for hover and high speed, but wouldn't that be less of a problem in tiltrotor? Not that i'm abandoning coaxial/intermesher in favour of tiltrotor BTW...
Mart
Nick, Good point well made. I was really wondering whether for a rigid rotor, such as will be used in the coaxial, a "bit of string" around the tips would improve figure of merit. The "bit of string" would be say a light flexible composite tube, with proportions chosen for minimum mass/unit_length for a given ability to trap the tip vortices. Only tensile strength/stiffness would really be required, assuming low RRPM droop did not cause interference in say a 3 or 4 bladed rotor.
The point about drag is well heeded. I did wonder about the magnus affect, but of course this only works in the forward portions (posibly causing unwanted ring distorsion). The tube would possibly need torsional stiffness for a specific aero sections. Keeping mass down thus becomes harder. It's just that other than Bell trying this on a 2-blade tail rotor, i was not aware of any main rotor studies.
----
"Frontier's currently proposal would be ideal for hover if it was a simple side-by-side configuration, however it is a side-by-side that is marginalized by the tilt-rotor features."
Which features are you refering to here, Dave?
"To achieve any semblance of fast cruise the above attributes of hover must be severely inhibited."
Agreed, that fixed twist will not be ideal for hover and high speed, but wouldn't that be less of a problem in tiltrotor? Not that i'm abandoning coaxial/intermesher in favour of tiltrotor BTW...
Mart