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Experimental Helicopter?
Just What Does This Include?

How about the "Lockheed Experience" leading up to the Cheyenne helo? There is definitely some interesting experiments that were carried out in the Lockheed Skunk Works; such as the activity conducted under the leadership of Irven "Irv" Culver.
There was a Discovery channel program that included some of the history leading up to the AH-56A Cheyenne showing very interesting performance capabilities, potentially useful to the homebuilt helo pilot if these could be adapted without extreme penalties of cost or other trade-offs.

The picture below shows one of the features demonstrated by the XH-51A, which was a predecessor to the Cheyenne.

Note the extreme lateral c.g. capability. Ray Prouty (who provided the picture) stated in his recently published (HeloBooks) "Helicopter Aerodynamics" that this was a 15-foot side mounted boom. The Discovery program also had a video clip showing a probe extending out of the nose of a helicopter, which hover taxiied up to a man standing on the ground, who then jumped up and suspended himself from the end of the probe, demonstrating a very large fore and aft c.g. range.

How was this achieved? This is definitely the upside, what is the downside? The rotor head was of a "hinge-less" design. Prouty further states, the "hinge-less" design suffers from the characterization that "they all shook". Lockheed added a fourth blade and controlled the shaking to a more pilot acceptable level.

During the experimental phase a version labeled the CL-475 was built and used as a test bed for a lot of the initial experimentation that was occurring. During one significant event, while test flight ops were occurring at Edwards A.F.B, engine problems occurred while the ship was some distance out on the dry lake bed. By the time the problem was fixed the pilots were no longer around and the mechanic, though only fixed wing rated with no helo time, opted to fly the helicopter back to base rather than trailer it. The operation was done successfully. I would have a very hard time believing that story if it involved any helo I've flown.

Mr. Prouty's book describes the Advanced Mechanical Control System (AMCS) used in the Cheyenne. He claims some very positive properties can be found in this design.
My experience working in a Navy development lab has led me to believe that the gestation period for a good idea from the demonstration of a prototype, to it's use in the field can be more than 20 years.
(One of many examples: We had digital circuits operating at 327 megahertz in 1969 and not just in the lab). Hence I believe that there are a lot of good ideas already demonstrated, just laying about waiting for "Their Time".

BTW, anyone professing to be a helicopter fan who doesn't have Ray Prouty's book in a very dog eared condition, suffers from some credibility loss, or is very neat in reading and re-reading the book. (See the HeloBooks ad this issue.)

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