Sikorsky X2 Coaxial Compound Helicopter Technology Demonstrator Aircraft Achieves 287.69 MPH: Is the Sikorsky S-97 Raider Compound Helicopter the U.S. Army’s Future Light Tactical Helicopter?

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By David Crane
defrev (at) gmail (dot) com

April 28, 2011
Last updated on 5/08/11.

The Sikorsky X2 Compound Coaxial Helicopter Technology Demonstrator Aircraft has been receiving a significant amount of positive media attention, lately, and for good reason. The X2 is a very interesting and seemingly highly-capable/high-speed dual-rigid-rotor compound helicopter prototype that achieved 250 knots (287.69 mph) in level flight at 70% power, last year, which is pretty damn impressive/fast for a helo. Not as fast as the Lockheed XH-51A Compound helicopter prototype, which reached 302.6 mph (unofficially) in 1967, mind you, but still fast.

The X2 utilizes two rigid counter-rotating main rotors (the “coaxial” part). The “compound” part is provided by the X2’s pusher propeller, which provides a significant amount of forward thrust. X2 Director, Flight Operations/Chief Test Pilot Project Test Pilot Kevin Bredenbeck certainly seems pretty hyped up about the X2’s capabilities, and who can blame him?

The Sikorsky X2 compound helicopter technology demonstrator aircraft arguably reprisents the closest a high-speed compound helicopter has come to going into production in a long time, probably since the excellent, formidable, and pretty damned fantastic Lockheed AH-56/AH-56A Cheyenne compound attack helicopter program bit the dust practically on May 19, 1969, and officially on August 9, 1972, due to political and financial factors. The production version/model of the X2 would be called the Sikorsky S-97 Raider “Light Tactical Helicopter” (PDF format), which would constitute the first in a new class of U.S. military combat helicopters. However, DefenseReview (DR) would like to see a full-size attack helicopter version of the design developed with the addition of short/stubby wings (not just the miniscule stubs shown in the S-97 concept images, but rather Lockheed AH-56-Cheyenne-type wings, i.e., real wings that actually do something) for additional lift/off-loading and weapons mounting/carriage (specifically, precision-guided rockets and missiles). DR hopes the X2/S-97 design can be scaled up and modified as we’re suggesting.

Let’s discuss the political factors involved in the Cheyenne’s unfortunate demise, for a moment. There were two factors: 1)U.S. Air Force pressure to kill it, and 2) supposed “changing Army doctrine”, which was most likely really just a result of factor one (U.S. Air Force’s enforcement of their high-speed/fixed wing hegemony). Both of these (again, most likely just cause and effect) were very bad and idiotic reasons to quash the program. According to a Summer 2006 Vertiflite article, “virtually all the problems with the rotor system were either solved or well on their way to resolution when the [Cheyenne] program was cancelled”, right before it was supposed to go into production. This “Cheyenne-was-perfected-before-getting-cancelled” assertion is backed up by Cheyenne technology director (Lockheed) Bob Wood, who told Defense Review the same thing during a phone interview with him. He basically said they had the Cheyenne all figured out (all safety issues solved) when they cancelled it.

So, why would the Air Force want to cancel the wonderful and highly-lethal Cheyenne? Insecurity and turf protection. Since the Cheyenne was extraordinarily fast and aeronautically capable (for a helicopter) and employed short “stubby” wings to offload the main rotor and provide additional lift, the Air Force was able to use the Johnson-McConnell agreement of 1966 to help affect the Cheyenne’s premature demise. The Air Force doesn’t like anything that can fly as fast and capably as the Cheyenne, and that utilizes fixed wings to help it to do so, particulary if that aircraft is highly-weaponized, and therefore highly-lethal. Think about it: an attack helicopter that can fly almost as fast as a Fairchild Republic A-10 Thunderbolt II “Warthog” ground attack/CAS (Close Air Support) aircraft (fixed wing), and play a similar ground-attack combat role. An AH-56A Cheyenne developmental prototype flew 253 mph (220 kt).

The Sikorsky X2 technology demonstrator’s coaxial counter-rotating dual-main-rotor design allows it to do away with both the tail rotor and stubby wings that were utilized by the Lockheed XH-51A and AH-56A by simultaneously providing addtional lift AND countering torque effect. However, why not go with both coaxial main rotors AND short/stubby wings for even more lift/off-loading and weapons mounting capability? Short wings come in pretty handy when you’re mounting precision-guided 70mm/2.75″ Hydra rockets and HellFire II missiles. Maximum weaponization/platform lethality is always a positive thing. The X2/S-97 Raider also takes advantage of all the technological advances made over the last 40 years to avionics, electronics, materials science, design software, and manufacturing and fabrication technologies and techniques.

Defense Review hopes the X2 prototype compound helo follow-on, the S-97 Raider (PDF format) light tactical helicopter, lives up to all the hype and is truly ready for primetime and not just another example of expensive military vaporware. If it’s viable for a reconnaissance/attack rotorcraft platform, and offers a combat capability above and beyond any/all existing Army rotorcraft, DR hopes the X2 eventually makes it to full-rate production for U.S. Army procurement/adoption in significant numbers. However, what we’d really like to see (in addition to X2 rollout) is the U.S. Army and Lockheed Martin scheme and collaborate to bring the AH-56 Cheyenne compound helicopter program back from the dead, U.S. Air Force be damned. The fact that the Cheyenne was actually perfected before it was unceremoniously cancelled all those years ago, combined with all of the technological advances that have taken place over the last four decades, should allow Lockheed Martin and the Army to develop an updated/upgraded Cheyenne for the future Army force that would blow the Boeing AH-64 Apache attack helicopter out of the water, or rather, the air. The Cheyenne appears to be a significantly larger aircraft (rotorcraft) than the X2, and it would provide some healthy competition that would provide the Army with more choices, aircraft number, and combat capabilities than just procuring and fielding the X2 by itself.

The fact is that the Cheyenne compound attack helicopter, once outfitted with all the latest and greatest avionics and weapons, can significantly outperform the Apache in virtually every respect and combat aspect. Anything/everything the Apache can do, the Cheyenne can do better and/or faster. The Apache was a big step backward from the Cheyenne with respect to both speed and overall flight performance. Defense Review sees no reason why a Cheyenne model can’t be developed that carriers AH-64D-type millimeter-wave radar targeting and weapons.

We’ll see if the Sikorsky S-97 Raider Light Tactical Helicopter (PDF format) somehow manages to make it past the U.S. Army’s aircraft procurement overseers in the U.S. Air Force, and eventually onto the Sikorsky assembly line.

Aurora Flight Sciences (AFS) has announced that it’s been selected by Sikorsky Aircraft Corporation (SAC) to design, develop, and build prototype S-97 Raider airframes.

Speaking of attack helicopters, a Sikorsky X2 attack rotorcraft is also on the drawing board.

By the way, whatever happened to the Piasecki X-49A Speeedhawk compound helicopter? That aircraft looked interesting.

Photo(s) Credit: Sikorsky Aircraft Corp. and Lockheed Martin Corp.

Company Contact Info:

Sikorsky Aircraft Corporation (SAC)
Email U.S. Military Sales:
Email Commercial/Intl. Sales:
Email Customer Service Engineering:

Paul Jackson
Communications Director
Sikorsky Aircraft Corp.
Office Phone: 203-386-7143

Marianne Heffernan
Communications Manager
Office Phone: 203-386-4373

Aurora Flight Sciences (AFS)
9950 Wakeman Drive
Manassas, VA 20110
Office Phone: 703-369-3633
Fax: 703-369-4514

Tom Clancy
Advanced Concepts and Tactical Systems
Aurora Flight Sciences (AFS)
9950 Wakeman Drive
Manassas, VA 20110
Office Phone: 703-331-1053
Fax: 703-369-4514

Javier de Luis
Research & Development (R&D)
Aurora Flight Sciences (AFS)
One Broadway 12th Floor
Cambridge, MA 02142
Office Phone: 617-500-4800
Fax: 617-500-4810

Patti Woodside
Public Relations (PR)
Aurora Flight Sciences (AFS)
9950 Wakeman Drive
Manassas, VA 20110
Tel: (703) 396-6304
Fax: (703) 331-1080

Lockheed Martin Corporation, Lockheed Martin
6801 Rockledge Drive
Bethesda, MD 20817-1803
Phone: 301-897-6000

© Copyright 2011 All rights reserved. This content/material may not be republished, broadcast, rewritten or redistributed without first receiving permission and providing proper credit and appropriate links.

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Sikorsky X2 Coaxial Compound Helicopter Technology Demonstrator Aircraft Achieves 287.69 MPH: Is the Sikorsky S-97 Raider Compound Helicopter the U.S. Army’s Future Light Tactical Helicopter? by

About David Crane

David Crane started publishing online in 2001. Since that time, governments, military organizations, Special Operators (i.e. professional trigger pullers), agencies, and civilian tactical shooters the world over have come to depend on Defense Review as the authoritative source of news and information on "the latest and greatest" in the field of military defense and tactical technology and hardware, including tactical firearms, ammunition, equipment, gear, and training.

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