Sikorsky is studying a stretched, higher weight UH-60X version of the S-70A Black Hawk to meet a US Army requirement to carry heavier loads. The stretched helicopter would have the same gearbox and rotor system as the Sikorsky S-92 Helibus, the first prototype of which is now undergoing flight testing.
"The first step would be to introduce these modifications for the Black Hawk, and then the Sea Hawk," says Sikorsky. The company is proposing that the standard H-61 fuselage would be stretched by 0.9-1.8m (3-6f t) , and the current twin 1,210kW (1,600shp) General Electric T700-700 turboshafts would be replaced by two 1,490kW CT7-8s.
The first S-92 prototype has been flying since December, and has expanded its flight envelope to a maximum level speed of 155kt (230km/h), sideward flight of 35kt, level turns at 30¹ bank angles at up to 150kt, pull-ups and push overs at up to 150kt, control reversals at up to 140kt and autorotation entry at 80kt.
Sikorsky says that a flight in late February was flown at the maximum gross weight of 10,900kg.
Five prototypes are planned for the 1,400h development programme. Aircraft No 1 is the ground test vehicle, which will carry out the 200h gearbox certification test among others. Aircraft No 2, now flying, will fly 340h.
Aircraft No 3 is intended as a systems test vehicle, flying for 432h, and is due to be delivered to West Palm Beach, Florida, in April. Aircraft No 4 will be an acoustics and options development platform, and will be the last of the five to fly in July 2000, logging 124h.
It will be preceded in the air by aircraft No5, which will be built to the utility transport specification and will fly at a maximum take-off weight of 12,000kg with an external load.
Source: Flight International
