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Date: Jul 29, 2011
Advancing Blade Concept
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... or ABC. Having certain requirements in itself it was also a part of other programs, including the LHX and X-wing programs.

It was to develop aircraft using powered-lift technology, utilizing coaxially-placed rigid rotors, or even tilt-rotors to allow the aircraft to take off and land vertically, and transition to fixed-wing flight. At high speeds, the retreating blades of the coaxial configuration were offloaded, since most of the load was supported by the advancing blades of both rotors and the penalty due to stall of the retreating blade was thus eliminated. Not only did it eliminate the need for a rear anti-torque system, but didn't even need wings for high-speed flight.

Sikorsky XH-59A aircraft were the first demonstrators for this technology in 1973. It achieved a 184mph level flight speed as a standard rotor-wing, but with auxiliary propulsion it achieved 274mph. 

One of the aircraft crashlanded on August 24, but was then converted into a wind tunnel test article, tested in the NASA Ames Research Center full-scale wind tunnel in 1978. In 1982 they proposed the XH-59A be converted into the XH-59B configuration with two GE T700 engines and a ducted pusher-propeller at the tail, but they didn't go with it.

The X-2 is the latest in Sikorsky's effort in developing the technology. The demonstrators first flight was in August 2008, and despite being retired 15 days ago, the concept is currently being developed into the S-97 Raider scout-attack aircraft.



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Date: Jul 29, 2011
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The X-2 demonstrator was retired this month?!? I can't believe I missed this news!



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Date: Jul 31, 2011
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This is going to be a painfully general topic. So many firms and so many programs incorporated this concept into their projects, it could go on and on.



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Alan Dallas


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Date: Jul 31, 2011
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Westland did some studies on the ABC too. It was a part of a program to study a high-speed compoud helicopter (presumably supersonic) and its flight performance and risks. I dunno how far the studies went though. :P



-- Edited by Leela25 on Sunday 31st of July 2011 07:56:48 PM

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Date: Jul 31, 2011
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That was the SSRH and it was to study the blades at supersonic speeds. In order do do so a durable blade would be needed, because the standard type couldn't withstand the stress of supersonic speed. 

Now here's an interesting thing; as you know most of the shockwaves created by normal supersonic aircraft are left behind. Well in this case they move along the blades the further they accelerate. But this can cause the blades to lose performance, which also means loss of airflow, which means loss of control.

That and it would be noisy as hell.



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Matt L. Webber
555


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Date: Jul 31, 2011
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W.Z. Stepniewski's intermeshing-rotor (Synchropter) concept with ABC principle...



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:D

The Advancing Eggbeater Concept!! XD

I know, zzzz.



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555 wrote:

W.Z. Stepniewski's intermeshing-rotor (Synchropter) concept with ABC principle...


 

That's pretty cool. It would be much more aerodynamically clean than the common coaxial layout, and just might reduce the sound of the blades.



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555


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http://www.unicopter.com/Quiet_Rotorcraft.html

Good info on that concept.



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Date: Jul 31, 2011
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Leela25 wrote:

Westland did some studies on the ABC too. It was a part of a program to study a high-speed compoud helicopter (presumably supersonic) and its flight performance and risks. I dunno how far the studies went though. :P


 

As long as you got a good powerplant, a good slender fuselage, and transitional-type blades I have no problem with a rotorcraft exceeding the limit of 250 mph. Otherwise you are just asking for trouble.



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Date: Jul 31, 2011
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What about the S-69's record of 303mph? Sidewinder just covered that!



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No he didn't, but I'm already aware of it. This is not fair, because I was speaking about standard helicopters. The S-69 had help... advanced blades and auxiliary turbojets.



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But you just said trasitional blades. The S-69 was just fine without such a thing.



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Of course, but it wasn't a supersonic aircraft, was it? If you want that, you need durable blades that morph to fixed-wing, or otherwise ones that stow away into the fuselage.



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-airfoil- wrote:
555 wrote:

W.Z. Stepniewski's intermeshing-rotor (Synchropter) concept with ABC principle...


 

That's pretty cool. It would be much more aerodynamically clean than the common coaxial layout, and just might reduce the sound of the blades.


 

Just to let you know, you've covered this one before in the dreadful "uncategorized" thread. Thanks to Triple-Nickel, however, I now have an excuse to delete the post!



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Date: Aug 2, 2011
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The crashed prototype that was converted to a wind tunnel test model

Sikorsky XH-59A ABC (S-69) aircraft picture



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Date: Aug 2, 2011
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XH-59 prototypes



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Date: Aug 2, 2011
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Now here's a beauty. The XH-59 with a shrouded propeller;



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Matt L. Webber


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Date: Aug 3, 2011
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Wow..another one thrown in with the Commanche. So much for the Vertical Lift Consortium (VLC)


http://www.ivertical-lift.org

What's up with the industry Sarah??
I thought all the helo indutries were supposed to band together because DOD was pissed about wasted money and projects like the Commanche and now the X-2? That was the intent of the VLC was it not????????????? I know. You're an engineer and may not have a say so with the higher echelons in Boeing, but have you heard anything with regard to Boeing's part in the VLC?

Best Regards,

Dave



-- Edited by davh12 on Wednesday 3rd of August 2011 08:44:54 PM



-- Edited by davh12 on Wednesday 3rd of August 2011 08:45:57 PM

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Date: Aug 7, 2011
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Hi all

From old French "aviation magazine"



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touratier


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Date: Aug 7, 2011
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Hello touratier, wonderful scans. The second scan is a 3-view for the Sikorsky S-72 prototype that tested the rotor system of the RSRA requirement.



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Date: Aug 8, 2011
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Hi Cristalblue

You are true, sorry......one more

from aviation week

Bye 



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touratier


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Date: Oct 20, 2012
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I just stumbled across this...



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Flyboy's Site

mil


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Date: Jan 25, 2014
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The XH-59 with a shrouded propeller



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