Sikorsky X2 coaxial heli developments.
Is this the picture?
-- IFMU
Last edited by IFMU; 9th Dec 2007 at 00:16. Reason: tpyo
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Mart,
Walter Rieseler is referred to, in Germany at least, as the 'forgotten pioneer'.
I think that you will find his unique control system very interesting. Here is information on it;
IFMU,
The grass is always greener on the other side.
Dave
Walter Rieseler is referred to, in Germany at least, as the 'forgotten pioneer'.
I think that you will find his unique control system very interesting. Here is information on it;
- Wilford WRK Gyroplane
- On the NACA Search page and Enter Search Term 'TN-492'.
- US patent 1,975,124
IFMU,
The grass is always greener on the other side.
Dave
Last edited by Dave_Jackson; 10th Dec 2007 at 03:52. Reason: To give Mr. Rieseler his correct first name.
In searching for the picture, I found this:
But this looks like an old picture compared to the december issue of AIN.
But this looks like an old picture compared to the december issue of AIN.
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Unable to download NASA pdf of control system analysis, but yes it was ahead of it's time. It certainly demonstrates that a cost effective hingeless gyro is practical. Maybe even manouvreable.
I think part of the difficulty with modern hingeless rotors is that the rotor frequency is so much higher now, due to the higher speeds and lower rotor mass. This means that any rotor eigenmode is comparable to the rotor frequency, so there is inevitably lead angle required in the pitch link. Although the tip radius was quite small, those tip heavy blades would likely have all sorts of interesting modes.
Actually, there are days when i catch myself wondering whether you are right about laterally seperated rotors. It would push roll reaction times way down, since heli does not have to pendulate to new equilibrium. I have even pondered about smaller control only rotors, like Sikorsky's early VS-300! But these days a good SCAS control system can response shape the cyclic input to get a reasonable response. I think keeping the cost and weight of the machine down is more important.
It will be interesting to see how the X2 development engineers overcome the difficulties if the envelope is pushed above 250KIAS. Clearly active tip control will become critical to avoid blade divergence. I would be curious how much higher the blade 1st bending frequency is pushed too. So roll response may approach that of fixed wing...
I think part of the difficulty with modern hingeless rotors is that the rotor frequency is so much higher now, due to the higher speeds and lower rotor mass. This means that any rotor eigenmode is comparable to the rotor frequency, so there is inevitably lead angle required in the pitch link. Although the tip radius was quite small, those tip heavy blades would likely have all sorts of interesting modes.
Actually, there are days when i catch myself wondering whether you are right about laterally seperated rotors. It would push roll reaction times way down, since heli does not have to pendulate to new equilibrium. I have even pondered about smaller control only rotors, like Sikorsky's early VS-300! But these days a good SCAS control system can response shape the cyclic input to get a reasonable response. I think keeping the cost and weight of the machine down is more important.
It will be interesting to see how the X2 development engineers overcome the difficulties if the envelope is pushed above 250KIAS. Clearly active tip control will become critical to avoid blade divergence. I would be curious how much higher the blade 1st bending frequency is pushed too. So roll response may approach that of fixed wing...
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Mart,
In IFMU's article it says;
You mention;
Why does Sikorsky feel that 6,500 pounds is the lower end for ABC helicopters? There does not appear to be any technical reason for this remark. Perhaps, Sikorsky has no interest in them, or in other companies, building ABC helicopters with less than 6 seats.
_____________
Rieseler's means of producing 'Absolutely' Rigid Rotors by using aerodynamically balanced pitch instead of aerodynamically balanced flap is ingenious.
I'm going to look into it further, since it might be a logical step toward the UniCopter's and the Nemesis' Advancing Blade Concept. It will be posted as a separate topic on a new thread from this X2 thread if it continues to look good.
Dave
In IFMU's article it says;
Grant emphasized that the X2 is a demonstrator for a “suite of technologies” that might have applications for future-design civilian and military rotorcraft, but it was unlikely that the twin coaxial main rotor system could be applied to smaller aircraft with smaller rotors due to its rigidity and resultant weight. “You’re probably not going to see these applications in the 3,000-pound weight class,” he said. “This [6,500 pounds] is around the size we would want to be the book end for the low end of the weight class. It is a lot easier to go big.”
I think keeping the cost and weight of the machine down is more important.
_____________
Rieseler's means of producing 'Absolutely' Rigid Rotors by using aerodynamically balanced pitch instead of aerodynamically balanced flap is ingenious.
I'm going to look into it further, since it might be a logical step toward the UniCopter's and the Nemesis' Advancing Blade Concept. It will be posted as a separate topic on a new thread from this X2 thread if it continues to look good.
Dave
Last edited by Dave_Jackson; 9th Dec 2007 at 18:48.
Here's another similar picture I found on some German site:
and this one was from last year:
-- IFMU
and this one was from last year:
-- IFMU
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International Internet Theft Ring.
quadrirotor,
The Austrian (OOPS make that German) pilot of the little coaxial must have gone on a diet. This time he was able to keep the craft off the ground.
Are you here to steal back the picture I stole from you?
Or, are you the one who just stole IFMU's X2 picture.
Dave
The Austrian (OOPS make that German) pilot of the little coaxial must have gone on a diet. This time he was able to keep the craft off the ground.
Are you here to steal back the picture I stole from you?
Or, are you the one who just stole IFMU's X2 picture.
Dave
Last edited by Dave_Jackson; 10th Dec 2007 at 17:18. Reason: OOPS added
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IFMU,
It's nice to see the X2 in the flesh at last (or was this a mockup?). Somehow it looks all innocent there, despite what it is going to achieve. I'm always amazed how a pile of parts can slowly, but magically, become a machine in the hands of talented test fitters.
I bet it's starting to look the business at Schweizer now...
It's nice to see the X2 in the flesh at last (or was this a mockup?). Somehow it looks all innocent there, despite what it is going to achieve. I'm always amazed how a pile of parts can slowly, but magically, become a machine in the hands of talented test fitters.
I bet it's starting to look the business at Schweizer now...
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Wikipedia entry..
http://en.wikipedia.org/wiki/Sikorsky_X2
Artist conception of a potential armed high-speed escort/attack variant of an X2 aircraft. X2 technology is envisioned to be applied to a wide range of typical rotorcraft roles.
I think this one has a better handling, as she could have a vectorizing tail...
-- IFMU
Looking at those pix reminds me of the ill fated Cheyenne......too complex for what you achieve.
P.S. Jeff Pino seems to be slipping the date again...first flight was supposed to be before Christmas.
P.S. Jeff Pino seems to be slipping the date again...first flight was supposed to be before Christmas.
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Originally Posted by LupinIII
At an all-hands meeting, Jeff Pino claimed first flight target date is 1/15.
A bare rotorhead run was performed late last month.
A bare rotorhead run was performed late last month.
Take your time guys, and make it the success it deserves to be.
Us X2 fans have waited patiently this long...
At an all-hands meeting, Jeff Pino claimed first flight target date is 1/15.
A bare rotorhead run was performed late last month.
A bare rotorhead run was performed late last month.
I guess we'll find out, in another month!
-- IFMU
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IFMU, i can only speak from the perspective of having been involved in the design, analysis, testing & development of many ground vehicles for various industries (it still ain't helicopters 
). Any particular objective date will be more a target for the engineer's to aim towards. A well run project will adjust to the development activities, but will not dictate them.
Let's face it this is a complex helicopter program, not a train timetable!
). Any particular objective date will be more a target for the engineer's to aim towards. A well run project will adjust to the development activities, but will not dictate them.Let's face it this is a complex helicopter program, not a train timetable!
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Mart;
The originally promised date was late 2006.
Perhaps the Engineering dept. should set the Engineering dept's target date. Not the Hyperbole dept.
Perhaps you recall;
The originally promised date was late 2006.
You say;-
"Any particular objective date will be more a target for the engineer's to aim towards."
"Any particular objective date will be more a target for the engineer's to aim towards."
Perhaps you recall;
"They’re calling their cocktail of integrated digital, aerolelastic and compound technology the X2 and say that its unique co-axial/pusher prop design will do 250 KTAS knots by the end of 2006. ..............
......... Jeff Pino, now in charge of Sikorsky’s strategic programs put his people in special shirts, had a mock-up ready, and pulsed people’s cell phones to get them to come to a briefing.
There were some interesting sidelights: the legendary Marat Tischenko, head of Mil under the communist USSR rose to his feet to challenge Finger on making ‘a mistake’ by selecting the co-axial design.
Finger paused, then turned away, body language suggesting this was no time - no time at all - to engage in a debate on the esoterics. ................."
David S. Harvey
......... Jeff Pino, now in charge of Sikorsky’s strategic programs put his people in special shirts, had a mock-up ready, and pulsed people’s cell phones to get them to come to a briefing.
There were some interesting sidelights: the legendary Marat Tischenko, head of Mil under the communist USSR rose to his feet to challenge Finger on making ‘a mistake’ by selecting the co-axial design.
Finger paused, then turned away, body language suggesting this was no time - no time at all - to engage in a debate on the esoterics. ................."
David S. Harvey