The obvious difference between the piston-powered R44 and the turbine-powered R66 is the engine, but there are other features that make the R66 an entirely new machine, even though there's no mistaking that it is a product of Robinson Helicopter. At $798,000, the R66 is more expensive than the R44, but in finally becoming part of the turbine helicopter manufacturing family, Robinson has carved out a new niche in the light helicopter market.
Put an R44 and R66 side-by-side, and the key differences are immediately apparent: the R66's eight-inch taller mast and eight-inch wider cabin. Thanks to the angled installation of the Rolls-Royce RR300 that powers the R66, Robinson engineers, led by chief engineer Peter Riedl, were able to carve out a 300-pound, 18-cu-ft baggage compartment directly under the rotor mast, so cargo doesn’t have much effect on center of gravity location, according to chief test pilot Doug Tompkins.
Pilots like the baggage storage area under the R44 seats, and even though Robinson had to meet the latest dynamic seat crashworthiness standards, Riedl and his team were able to retain storage areas under four of the R-66’s seats (the fifth seat in the center rear has no storage). “We're the only manufacturer able to pass the latest crashworthiness and still retain some of our baggage space,” Tompkins said.
The R66’s hydraulically boosted flight controls are the same as those of the R44, except for longer parts for the taller mast. “As soon as they pick it up [into a hover], everyone says the R66 handles just like an R44, as far as controllability goes,” Tompkins said. Transitioning from the R44 to the R66 is mostly a matter of learning how to operate the engine.
The R66 tailrotor is two inches larger in diameter, so the total helicopter length is one inch longer than the R44. Tailrotor blades are about a half-inch wider in chord, and the tailrotor hub is redesigned to reduce vibration, with a thinner hub but beefier bolts. The R66 incorporates the “whale tail” auxiliary stabilizer used on the float-equipped R44. The tail keeps the nose from rising during autorotation. It was always part of R66 flight testing and provides better longitudinal stability.
When pushing open the step cover to climb to the top of the fuselage during preflight, LED lights turn on to light up the sight glasses for the hydraulic reservoir and transmission fluid. “Sometimes with the sun [shining] it’s kind of hard to see in there,” Tompkins explained.
Another improvement deserving attention is a handy airspeed limitation chart mounted on the cyclic for easy viewing during flight. The chart is printed on a plastic housing that rotates so the applicable temperature and limitations can easily be viewed, instead of having to squint at a hard-to-see sticker mounted elsewhere in the cockpit.
There’s more to the R66, including what Tompkins said is “very impressive” performance, thanks to the Rolls-Royce 300’s available power (300 shp, derated to 270 for takeoff and 224 max continuous). Most recently, Robinson has received certification of the R66’s air-conditioning system and plans are underway to offer emergency floats and a four-point seatbelt harness.