Robinson considered compound R44

Frank Robinson says he studied a compound version of the piston-powered four-seat R44 Raven helicopter, but ultimately dropped the idea.

“It’ll work, but it didn’t give me the improvement in efficiency or performance in the speed range I wanted,” he says.

I was fortunate to spend 15 minutes with Robinson yesterday afternoon. The helicopter industry icon, now retired and turning 81 next week, was at the office on Torrance boulevard in Los Angeles, the location where he’s built Robinson helicopters since the 1970s.

Earlier in the day, we (Flight International) experienced Mr. Robinson’s latest and greatest, the Rolls-Royce powered R66 turbine, a helicopter that represents the culmination of his more than four decades of engineering in the industry – his swan song. (I’ll talk about all of that in later blog posts, and in Flight International’s 1March magazine, where we’ll have an R66 pilot report by Peter Gray and many other civil helicopter features.)

Here’s a picture I took of the R66 on 5 January from an R44 photo ship.

R66_5 Jan 2011.JPGWhen I asked Frank what he thought about the success of the Sikorsky X2 compound helicopter, he brought up the R44 project.

He never actually built one, but did a series of dive tests on the R44 to determine the extra power that would be needed. The configuration was to be the standard R44 with anti-torque rotor on the tail, but with a pusher propeller on the longitudinal axis as well to push speeds up to the 140-150kt range.

Too bad it didn’t play out.

Robinson continues to ponder electric power to this day. When asked about Sikorsky’s all-electric Firefly helicopter, which was supposed to have had first-flight by now, Robinson said that’s an area in which he is also very interested in, but not for the usual environmental reasons of saving gas and cutting emissions.

Robinson would like to use electric propulsion as a backup power mode to give single-engine helicopters an added safety margin compared to a twin. It’s brilliant – all the safety features without the added cost, weight and fuel burn…

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