The Way Things Might Have Been

[Dave Jackson]

The only two production helicopters in the early 40's were the Sikorsky R-4B and the Flettner FL-282B. The intermeshing Flettner outperformed the single rotor Sikorsky in most categories, including top speed. Today the single rotor is the pre-eminent configuration, whereas the intermeshing configuration is at the point of extinction. Why?
Charles Kaman took up the German intermeshing (synchropter) configuration and married it to the Italian servo-flap flight control. It has been said that he attempted to develop the intermeshing helicopter using blade-root-pitch control, but found it unworkable. This is unusual in that the earlier Flettner FL-282B and the later Dick DeGraw Hummingbird both used blade-root-pitch control. One might assume that Charles Kaman, like most inventors, had an affinity for his own ideas.
It would appear that if 50 years ago the, easier to fly, intermeshing configuration had been allowed to develop, unencumbered by the 'servoflap' control, it might have been today's pre-eminent helicopter configuration.


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Dave J Project: SynchroLite.com

[helisphere]

The reason I heard for Kaman using the servo tab coupled with a non rotating blade root, was simply it was easier to make a blade torsionally soft than stiff (especially in those days). There are also structural advantages and control load and feedback advantages to controlling blade pitch from the outer end with a servo flap as opposed to the root with a mechanical pitch link. I don't think Kaman found root control unworkable, I think he found his way to be simpler.

As for intermeshers or co-axials I am a big fan but they do have some serious limitations with yaw control. I think those limitations could be over come though.

[This message has been edited by helisphere (edited 22 January 2001).]