Westland built version of the Sikorsky S-51
Rotor diameter: 14.63 m
Length: 17.54 m
Weight: 2004 kg - Max.2675
Power: 1 Alvis Leonides 50 (540 hp)
Range: 482 Km
Acommodation: Pilot plus 4
No.Built: 149
Unless Nick Lappos says something to the contrary, all production Sikorsky helicopters have the same design philosophy relative to input of control to the rotorhead. On the S-51 the original design used mechanical jackscrews operated by cables and chains. In about 1949 or 1950 they were equipped with hydraulic servos. At about the same time they were equipped with metal blades. Some retained the wood three blade tail rotor and most were equipped with a two blade metal tail rotor.
I worked on two of them that were modified as above. The Greyhound Bus Company for VIP transport in the Boston area originally purchased these helicopters. The costs were too high so they were sold to the US Coast Guard and as such had a luxury look to them in the cabin area.