https://en.wikipedia.org/wiki/McDonnell_XHJH_Whirlaway

The McDonnell XHJH Whirlaway was a 1940s American experimental twin-rotor
helicopter designed and built by McDonnell Aircraft for the United States Navy.
It was the first successful twin-engined, twin rotor helicopter in the world.
The Whirlaway was the largest helicopter flown up to that time.

Role
Experimental twin-rotor helicopter

National origin
United States

Manufacturer
McDonnell Aircraft

First flight
27 April 1946

Number built
1

In 1944, the United States Navy issued a requirement for a large rescue
helicopter with capacity for ten occupants. The design was originally designated
XHJD-1; shortly after flying it was re-designated the XHJH-1. The XHJH-1 first
flew in August 1944, and had twin side-by-side 46 ft (14 m) rotors at the end of
pylon wings which turned in opposite directions. Each rotor was powered by a 450
hp (336 kW) Pratt & Whitney R-985 engine.

The sole XHJH-1 is held by the National Air and Space Museum.

Specifications

Length: 32 ft 2 in (9.80 m)
Powerplant: 2 × Pratt & Whitney R-985 , 450 hp (340 kW) each
Main rotor diameter: 2× 46 ft 0 in (14.02 m)

Performance
Maximum speed: 120 mph (193 km/h; 104 kn)
Cruise speed: 90 mph (145 km/h; 78 kn)
Range: 300 mi (261 nmi; 483 km)




*