Sikorsky X2 coaxial heli developments.
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X2 pusher prop
First post to a great site.
I've got a question for all you smart folks and I realize that I may not have the proper knowledge to word this question so please ignore my ignorance.
The question is-looking at the Sikorsky X2 aircraft can anybody estimate how much thrust that pusher prop is creating? If so, can anybody tell me the formula of how you figure the thrust of a propeller?
Thanks, MjH
I've got a question for all you smart folks and I realize that I may not have the proper knowledge to word this question so please ignore my ignorance.
The question is-looking at the Sikorsky X2 aircraft can anybody estimate how much thrust that pusher prop is creating? If so, can anybody tell me the formula of how you figure the thrust of a propeller?
Thanks, MjH
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X2 Pusher Prop & Thrust Calculation
Welcome to the forum Rusty - I doubt you're really "Old" ! I'm sure that one of the Sikorsky guys can help you with the rated thrust of the X2's prop. I used to know one of the program pilots Kevin Bredenbeck so maybe you can try his name in the standard Sikorsky email format; [email protected]. Most of those guys are quite bright and also like to share their love of rotorcraft knowledge with others so he will probably give you more than you want or even need to know !
As for the formula; I used to have it in my old college aero textbook but its long gone. In simple terms, its just geometry and fluid mechanics with a few other minutae. Google is your friend - don't need to pull out the old textbooks anymore :-)
As for the formula; I used to have it in my old college aero textbook but its long gone. In simple terms, its just geometry and fluid mechanics with a few other minutae. Google is your friend - don't need to pull out the old textbooks anymore :-)
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MjH,
The thrust of a propeller is roughly 5 lbs per horsepower for relatively small aircraft.
The following are approximate values for the X2. The gross weight is 6,095 lbs. The power of the engine is 1,450 SHP. The X2's rotors maybe in a low-rpm powered state or in an autorotative state at maximum forward speed. It has been mentioned that the craft was using somewhere around 80% power at this speed.
The high parasitic drag of the X2 is one of it's primary limitations, since drag increases at the square of the forward velocity. Hypothetically, the X2 could just about takeoff and hover on its prop as a Tailsitter. 6,095 lbs / (1450 x 0.8) = 5.25 lbs per horsepower.
The following may provide you with a more exact answer.
I think that Aero Composites, Inc. provided the propeller.
The propeller specifications plus this article Theoretical Max Propeller Efficiency may be of value. The article was written by an engineer at CarterCopters.
If you get some information from Sikorsky, please post it. There is nothing better then the facts.
Dave
The thrust of a propeller is roughly 5 lbs per horsepower for relatively small aircraft.
The following are approximate values for the X2. The gross weight is 6,095 lbs. The power of the engine is 1,450 SHP. The X2's rotors maybe in a low-rpm powered state or in an autorotative state at maximum forward speed. It has been mentioned that the craft was using somewhere around 80% power at this speed.
The high parasitic drag of the X2 is one of it's primary limitations, since drag increases at the square of the forward velocity. Hypothetically, the X2 could just about takeoff and hover on its prop as a Tailsitter. 6,095 lbs / (1450 x 0.8) = 5.25 lbs per horsepower.
The following may provide you with a more exact answer.
I think that Aero Composites, Inc. provided the propeller.
The propeller specifications plus this article Theoretical Max Propeller Efficiency may be of value. The article was written by an engineer at CarterCopters.
If you get some information from Sikorsky, please post it. There is nothing better then the facts.
Dave
Last edited by Dave_Jackson; 10th Jul 2011 at 21:43. Reason: Corrected the speculation as to the state of the rotors during maximum forward speed.
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Dave and FlyHi, thanks to both of you for great answers. I will do some reading from those articles. I promise to post anything I find that's concrete, though I doubt Sikorsky will openly answer any pointed questions about their new toy (and I don't blame them for that
The last flight of X2
As reported on the Sikorsky homepage:
Award-Winning X2 Technology Demonstrator Takes its Final Flight - Program paved the way for upcoming S-97 Raider helicopter
Award-Winning X2 Technology Demonstrator Takes its Final Flight - Program paved the way for upcoming S-97 Raider helicopter
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From Flight:
I/C
A picture released by Sikorsky showed that the sail fairing was absent on the X2's final flight.
Sikorsky later explained that the sail fairing was sacrificed to apply more resources to meeting a "fairly aggressive" schedule for flying the first two S-97 prototypes within three years.
"We had planned to install and test the fairing but have since decided our focus needs to shift 100% to the S-97 Raider," Sikorsky said.
Sikorsky later explained that the sail fairing was sacrificed to apply more resources to meeting a "fairly aggressive" schedule for flying the first two S-97 prototypes within three years.
"We had planned to install and test the fairing but have since decided our focus needs to shift 100% to the S-97 Raider," Sikorsky said.
aka...they couldnt work the bugs out of its operation. Interesting as the sail fairing was one of the key peices of technology that differentiated the X2 from the XH59A. Had the XH59B been built and taken flight, it would have been largely the same aircraft as the current X2 minus all of the FBW controls.
Remember that something like 40% of drag was from the rotor mast, so flying without the highly developed sail fairing on it is a pretty big deal IMO.
One major concern for the X2 has got to be fuel burn in addition to noise signature. SAC has been mum on these points.
Remember that something like 40% of drag was from the rotor mast, so flying without the highly developed sail fairing on it is a pretty big deal IMO.
One major concern for the X2 has got to be fuel burn in addition to noise signature. SAC has been mum on these points.
Maybe the S-97 prototypes will allow them some time and opportunity to work the fairing issue.
From a late 2010 Sikorsky "Frontlines" release.
From a late 2010 Sikorsky "Frontlines" release.
S-97 Raider helicopter prototypes will feature twin coaxial counter-rotating main rotors (in place of one main rotor and a tail rotor) and a pusher propeller.
{Describes modular design, to run a small (six person) assault, or more fuel and run a recon/weapons mission}.
In addition to flying at nearly twice the speed of a conventional helicopter, the S-97 Raider prototype aircraft will incorporate other key performance parameters critical to combat operations — increased maneuverability, greater endurance, and the ability to operate at high altitudes.
Compared to other light military helicopters, the Raider prototypes are expected to significantly reduce turning radius and acoustic noise signature, while significantly increasing the aircraft’s payload, flight endurance and hot and high hover capability.
The company expects to conduct its first major program milestone — a preliminary design review — in 2011. First flight, projected in four years, could depend in part on the pace of development and customer need.
{Describes modular design, to run a small (six person) assault, or more fuel and run a recon/weapons mission}.
In addition to flying at nearly twice the speed of a conventional helicopter, the S-97 Raider prototype aircraft will incorporate other key performance parameters critical to combat operations — increased maneuverability, greater endurance, and the ability to operate at high altitudes.
Compared to other light military helicopters, the Raider prototypes are expected to significantly reduce turning radius and acoustic noise signature, while significantly increasing the aircraft’s payload, flight endurance and hot and high hover capability.
The company expects to conduct its first major program milestone — a preliminary design review — in 2011. First flight, projected in four years, could depend in part on the pace of development and customer need.
Those interested in this program might want to keep an eye on how steep DoD budget cuts are. This program may be at risk in the fight for dollars. (Recalling what happened to Comanche ... )
Lone
The fairing could be the issue, but it could also be that the processed the loads data, started getting chips in an xmsn, or found a crack or two in critical components.
Just a few weeks after stating the final goal and suddenly abandoning it for "manpower" indicates a more serious issue than taking a little time to install a fairing.
The Sultan
The fairing could be the issue, but it could also be that the processed the loads data, started getting chips in an xmsn, or found a crack or two in critical components.
Just a few weeks after stating the final goal and suddenly abandoning it for "manpower" indicates a more serious issue than taking a little time to install a fairing.
The Sultan
I would think that if the sail fairing was a big deal, and they hit their goals without it, it says they had a fair margin of performance. But, this is a rumor network, and a theory like that may not sound as fun as something more sinister. I'm sure none of my fellow Ppruners would just make something up and post it!
-- IFMU
-- IFMU
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I would think that if the sail fairing was a big deal, and they hit their goals without it, .......
And exactly what were these achieved goals??????
Dave,
From here:
Sikorsky X2 Technology
it says:
“The X2 Technology demonstrator program set out to accomplish four key performance objectives: low single pilot work load, low vibration, low acoustic signature, and speed – defined as cruise at 250 knots,” said Jim Kagdis, program manager for Sikorsky’s Advanced Programs. “There was a fifth key objective that remains a driving force to all that we do at Sikorsky: to preserve the legacy and pioneering spirit of our company founder, Igor Sikorsky, and to educate and inspire the next generation of engineers and aviation professionals. The Collier Trophy exemplifies this fifth objective, so it is hugely rewarding for the team to stand recognized for upholding the basic tenets on which Sikorsky Aircraft was founded. I am extremely proud of the team and our accomplishment.”
So to enumerate those goals from the above:
1) Low pilot workload
2) Low vibration
3) Low acoustic signature
4) 250 kts
5) Inspire the next generation
-- IFMU
From here:
Sikorsky X2 Technology
it says:
“The X2 Technology demonstrator program set out to accomplish four key performance objectives: low single pilot work load, low vibration, low acoustic signature, and speed – defined as cruise at 250 knots,” said Jim Kagdis, program manager for Sikorsky’s Advanced Programs. “There was a fifth key objective that remains a driving force to all that we do at Sikorsky: to preserve the legacy and pioneering spirit of our company founder, Igor Sikorsky, and to educate and inspire the next generation of engineers and aviation professionals. The Collier Trophy exemplifies this fifth objective, so it is hugely rewarding for the team to stand recognized for upholding the basic tenets on which Sikorsky Aircraft was founded. I am extremely proud of the team and our accomplishment.”
So to enumerate those goals from the above:
1) Low pilot workload
2) Low vibration
3) Low acoustic signature
4) 250 kts
5) Inspire the next generation
-- IFMU
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Goals:
That is a very insipid list of goals. Four of the five could apply to a lawn mower.
The predominant focus of the marketing was the 'targeted' 250-knot speed.
Therefore, where did this 253-knot 'record' come from; the Pitot tube, the local sheriff's radar gun, a desk in the marketing department? It certainly did not come from the Fédération Aéronautique Internationale, which Sikorsky had previously cited.
The predominant focus of the marketing was the 'targeted' 250-knot speed.
Therefore, where did this 253-knot 'record' come from; the Pitot tube, the local sheriff's radar gun, a desk in the marketing department? It certainly did not come from the Fédération Aéronautique Internationale, which Sikorsky had previously cited.
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Hi Nick,
As for achieved goals, I build a manufacturing company, got bored, sold it, and retired at 47. But this subject is of little relevance and is off-topic.
Want to have some technical conversations?
Dave
As for achieved goals, I build a manufacturing company, got bored, sold it, and retired at 47. But this subject is of little relevance and is off-topic.
Want to have some technical conversations?
Dave
Dave, are you interested in a technical discussion? 
From above:
IFMU says
If yes, I'd consider Dave Jackson enterprises both successful and inspirational.
(Oh, and where does one find these, at Lowes or at Home Depot? 
)
My neighbors would be much obliged, what with me cutting the grass in the mornings ...
Back to the fairing:
In program concept and implementation, it seems to me shortsighted to demand that the fairing be a serial, verus parallel, design criterion when you are building a scale prototype. It was proof of concept, was it not? Performance goals included the 250 knots, right? Goal met?
From where I sit, there is time to deal with the fairing as the "closer to production sized prototypes" go through the design and design reviews, don't you think?
Scope limitations in a program: a requirement.
From above:
IFMU says
1) Low pilot workload
2) Low vibration
3) Low acoustic signature
4) 250 kts
5) Inspire the next generation
Dave says2) Low vibration
3) Low acoustic signature
4) 250 kts
5) Inspire the next generation
That is a very insipid list of goals. Four of the five could apply to a lawn mower.
Technical question: was your manufacturing company an enterprise that build 250-knot, low vibration lawn mowers that could boast low pilot work load and low acoustic signature? If yes, I'd consider Dave Jackson enterprises both successful and inspirational.
(Oh, and where does one find these, at Lowes or at Home Depot? ) My neighbors would be much obliged, what with me cutting the grass in the mornings ...
Back to the fairing:
In program concept and implementation, it seems to me shortsighted to demand that the fairing be a serial, verus parallel, design criterion when you are building a scale prototype. It was proof of concept, was it not? Performance goals included the 250 knots, right? Goal met?
From where I sit, there is time to deal with the fairing as the "closer to production sized prototypes" go through the design and design reviews, don't you think?
Scope limitations in a program: a requirement.
If everything else is in place I would have thought this effort shouldn't have been too high and you could learn potentially important things early giving you time to work on it systematically without the ususal rush/stress/time limitations in the 'real' project.
Maybe the budget was simply consumed by then and it was not considered worthwhile...
Coming from an engineering background myself I feel with the engineers/designers who would have surely loved to test it.
Dave,
You taught me something. I had no idea what insipid meant. I have looked it up and am now one word smarter. Thanks!
In the context of the helicopter industry, I have a hard time understanding these to be insipid goals. In particular, the 250 kt goal. If a 250 kt helicopter doesn't get your fires burning, then your wood is wet!
-- IFMU
PS Nick good to see you back.
You taught me something. I had no idea what insipid meant. I have looked it up and am now one word smarter. Thanks!
In the context of the helicopter industry, I have a hard time understanding these to be insipid goals. In particular, the 250 kt goal. If a 250 kt helicopter doesn't get your fires burning, then your wood is wet!
-- IFMU
PS Nick good to see you back.
Last edited by IFMU; 21st Jul 2011 at 01:47. Reason: PS