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Sikorsky X2 coaxial heli developments.

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Sikorsky X2 coaxial heli developments.

Old 30th Jul 2008, 01:26
  #301 (permalink)  
 
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Some of the statements on this thread seem to assume different things. For example:

Originally Posted by Graviman
Nick, my confusion comes from the fact that XH-59 had two rotor speeds while X-2 has apparently a variable rotor speed.
I think it has been stated previously in this thread that the XH-59 had two rotor speeds, and I interpret the discussion as though there were a physical gear change, like a motorcycle or car. This seems odd. Then we get:

Originally Posted by NickLappos
Dave is right, the ABC cruised in autorotation at about 250 knots. The collective was raised so that the rotor rpm settled at about 88% Nr.
Now, does this imply that the gearshift was connected to the collective? Or they used collective pitch to control RPM just like any helicopter in autorotation? Or is there something more sinister going on, like the CVT (continuously variable transmission) in my 1971 Harley golf cart?

-- IFMU
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Old 30th Jul 2008, 04:55
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The attached page is from a document on the XH-59A ABC after a 128 hour flight test program.

The center paragraph in the right hand column is directly related to the subject of your post.



It has been said that the rotor hub constituted 50% of the craft's total drag. This combined with other information on this page could be related to the current subject.

Maybe the lower RRPM for high-speed flight was not actually 'geared' into to the craft. Maybe it was an aerodynamically generated rotor speed.


Dave
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Old 30th Jul 2008, 19:32
  #303 (permalink)  
 
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A long time ago but

As I recall, the transition to thrust augmented flight was relatively benign. For takeoff we set the collective at approximately 25-30% then performed a traditional airplane takeoff and transition using the thrust from the J60s. As the airspeed increased the Q from the PT-6s decreased to 0% and the rotor speed settled in at 88% with the freewheeling units disengaged. The transition from for forward flight was just as benign. We reduced the thrust from J60s. As the airspeed decreased the PT6 torques increased to bring the rotor speed back to 100%. We then adjusted the collect and proceeded to fly a traditional helicopter. All and all, an easy aircraft to fly. Back then I would have rated it an E ticket ride.
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Old 17th Aug 2008, 21:22
  #304 (permalink)  
 
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Some more information

X2TD Power Train:
- "The engine output shaft drives the input of a splitter gearbox mated to the rear of the coaxial gearbox through an overrunning clutch. The splitter gearbox drives the coaxial gearbox and a shaft that drives the auxiliary propulsion gearbox located in the tail. The variable-pitch auxiliary prop is therefore geared to the main rotors at all times."

Rotor lift/drag comparison between XH-59A and X2TD
- Additional technical information has been added to this page.
- More stuff can be added if requested.
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Old 18th Aug 2008, 17:00
  #305 (permalink)  
 
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Dave, that web page is getting interesting! Have you got the rest of that XH-59 document?

Jack, thanks for clearing up the confusion. With an overrun clutch allowing autorotation i can now understand an Nr of 88%. I imagine that the J60s did not produce much thrust at low speeds, so that the PT6s actually generated most of the "airplane" thrust (through the rotor). So you were using the collective to trim for level flight (or climb/descent) as the speed increased/decreased? Was there a particular speed where you found you were retrimming the collective more regularly?

CEFOSKEY, do tell! Has the bird made a hop yet, or did it just go light on the gear?

Last edited by Graviman; 20th Aug 2008 at 12:22.
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Old 18th Aug 2008, 21:44
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Mart,
Dave, that web page is getting interesting! Have you got the rest of that XH-59 document?
Yes. The page on Posting #303 is from 'An ABC Status Report'

These are the Technical Documents that I have;
Technical Documents on S-69 (XH-59) ABC:
Technical Documents on X2 TD ABC:


On this subject of Rotor Shaft Angle, this section has been added to the X2TD web page.

Dave
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Old 19th Aug 2008, 02:20
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Smile

CEFOSKEY

Thanks. The change has been made. That's; one error down, hundreds to go.

Apparently the craft went under a number of designations, such as; XH59, XH59A, S69, proposed XH59B,
but never S76

________________________

IFMU is probably going to ask Graviman;
how do you connect a turbojet to a turboshaft engine?
Use the turbojet as the compressor stage?


Dave

Last edited by Dave_Jackson; 19th Aug 2008 at 06:30.
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Old 19th Aug 2008, 03:32
  #308 (permalink)  
 
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Originally Posted by Graviman
I imagine that the J60s did not produce much thrust at low speeds, so that the PT6s actually generated most of the "airplane" thrust (through the rotor).
I would think the rotors and PT6's were decoupled from the J60's, so as the rotor RPM wound down the J60's would be singing their hearts out. After all, how do you connect a turbojet to a turboshaft engine?

-- IFMU
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Old 20th Aug 2008, 12:35
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Wow, and it's contained in its own con-di nozzle too! I gotta get me one of those...

IFMU, what i mean is that the J60 thrust would be very low at slow speeds, increasing with airspeed - this is a turbojet not the later turboshaft version. This is because the intake area is relatively small, so needs airspeed to get enough mass flow. So to get up to that speed the rotor would have done most of the work, even though the J60s were spooling themselves silly. That's why the collective at low speed is 25-30%, since the PT6s are doing most of the work. With airspeed the PT6 Q, and collective, goes down to zero as the J60 takes over providing the thrust.

PT6s and J60s are connected together by means of sitting in the same airflow.
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Old 21st Aug 2008, 12:24
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CEFOSKEY, this does my head in too. Jack Carson's comments are not dissimilar to the test pilot comments on the Lockheed XH-51 (similar to S69 with PT6 driving rotor and J60 Turbojets) and BELL 533 (T53 driving rotor and J69-T-9, later J69-T-29, turbojets), in that the rotor was providing most of the thrust at low speed. I read this in Prouty somewhere (i think).

Turbojet Thrust



Bell 533 - Wikipedia, the free encyclopedia
Lockheed XH-51 - Wikipedia, the free encyclopedia

Last edited by Graviman; 21st Aug 2008 at 12:39.
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Old 27th Aug 2008, 21:07
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X2 flew for the first time today...

HORSEHEADS, N.Y., Aug. 27, 2008 – Sikorsky Aircraft Corporation today successfully completed the first flight of its X2 TECHNOLOGY™ Demonstrator, maneuvering the prototype aircraft through hover, forward flight, and a hover turn, in a test flight that lasted approximately 30 minutes. Sikorsky is a subsidiary of United Technologies Corp. (NYSE:UTX).

Sikorsky Chief Test Pilot Kevin Bredenbeck conducted the test flight at Sikorsky’s Schweizer Aircraft Corp. rapid-prototyping facility in Horseheads, N.Y. The milestone culminated more than four years of design, development and testing of the Demonstrator aircraft’s suite of technologies that are intended to advance the state-of-the-art, counter-rotating coaxial rotor helicopter.

“Today’s achievement is the result of dedicated effort by the entire X2 TECHNOLOGY Demonstrator Program Team,” said James Kagdis, Program Manager, Advanced Programs. ”It is proof of the complete commitment by Sikorsky Aircraft to this program and to the exploration of innovation in aviation. We look forward to expanding the flight envelope for this Demonstrator and will continue to conduct market analysis to determine the next steps for this important program.”

The X2 TECHNOLOGY Demonstrator is designed to establish that a helicopter can cruise comfortably at 250 knots, while retaining such desirable helicopter attributes as excellent low speed handling, efficient hovering, and safe autorotation, combined with a seamless and simple transition to high speed.

Sikorsky President Jeffrey P. Pino said the successful first flight attests to the company’s commitment to excellence and to industry-leading innovation.

”X2 TECHNOLOGY has crossed a major threshold,” Pino said. “The team’s achievement sets the stage for the next series of tests eventually leading to maximum speed. It also sparks the imagination for what ultimately the technology can mean to the future of the rotorcraft industry. We are far from having a product, but closer than ever to realizing the potential.”
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Old 28th Aug 2008, 12:36
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Seriously well done X2 development team!!



Your fans will patiently wait, while the flight envelope is explored, to see what this new type of flying machine brings...

Mart


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Last edited by Graviman; 28th Aug 2008 at 12:53.
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Old 28th Aug 2008, 13:42
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Video please!...
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Old 28th Aug 2008, 16:30
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A photo:

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Old 28th Aug 2008, 17:44
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And the other one:

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Old 28th Aug 2008, 22:35
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.

You must all be seeing something I can't.

No retractable u/c, back end sits on a trolley when on the ground, counterote is old technology and looks like only a two person capacity?

The only use I can see is for business users and there are others already established on the market. However as a concept vehicle, it's another step forward.
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Old 28th Aug 2008, 22:51
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Understand that but other than improving technology? So, it can go faster - yes, why?
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Old 28th Aug 2008, 23:57
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Originally Posted by Glory View Post
So, it can go faster - yes, why?
Er, to get there sooner. Why else would you want any vehicle to travel faster...?
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Old 29th Aug 2008, 00:13
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Understand that but other than improving technology? So, it can go faster - yes, why?
The answers may be in this technical document from the AHS May 2008 Conference;

X2 Technology™ and Emerging Applications ~ by Eadie, Alber & Tinker


Dave
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Old 29th Aug 2008, 01:22
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From Aviation International News today.

Compound Sikorsky X2 Makes First Flight
Thirty-eight months after Sikorsky’s formal announcement of the X2 “technology demonstrator,” the compound helicopter made its first flight yesterday at the Sikorsky-Schweizer rapid prototyping facility in Horseheads, N.Y. During the 30-minute flight, Sikorsky chief test pilot Kevin Bredenbeck conducted slow forward flight, hover and hover turn maneuvers. The rear propulsor was not engaged during the inaugural flight, and the X2 reached a maximum forward speed of 20 knots, 10 to 15 knots sideways and 40 feet agl. More slow flight testing will be conducted at Horseheads before the X2 is transferred to Sikorsky’s larger West Palm Beach, Fla. flight-test facility. Sikorsky is self-financing the fly-by-wire X2 with an eye to deploying its key components in future manned and unmanned military helicopters. The X2 is designed to have a maximum forward speed of 250 to 265 knots. Power for the X2 comes from a single LHTEC–Light Helicopter Turbine Engine Company, a Rolls-Royce and Honeywell partnership–T800 turboshaft engine rated at up to 1,680 shp. The T800 drives the twin four-blade Eagle Aviation contra-rotating main rotors and the Aero Composites six-blade pusher propeller mounted at the end of the tailboom.
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