Sikorsky S-76

https://en.wikipedia.org/wiki/Sikorsky_S-76

The Sikorsky S-76 is an American medium-size commercial utility helicopter,
manufactured by the Sikorsky Aircraft Corporation. The S-76 features twin
turboshaft engines, four-bladed main and tail rotors and retractable landing
gear.

The development of the S-76 began in the mid-1970s as the S-74, with the design
goal of providing a medium helicopter for corporate transportation and the oil
drilling industry; the S-74 was later re-designated the S-76 in honor of the
U.S. Bicentennial. Sikorsky's design work on the S-70 helicopter (which was
selected for use by the United States Army as the UH-60 Black Hawk) was utilized
in the development of the S-76, incorporating S-70 design technology in its
rotor blades and rotor heads. It was the first Sikorsky helicopter designed
purely for commercial rather than military use.

Role
SAR/utility helicopter

Manufacturer
Sikorsky Aircraft

First flight
March 13, 1977

Status
In service

Primary users
Bristow Helicopters
CHC Helicopter

Produced
1977-present

Number built
1,090 (All variants) as of June 2015

Unit cost

US$13 million (2014)


Variants
Sikorsky S-75

The S-76 is of conventional configuration, with a four-bladed fully articulated
main rotor and a four-bladed anti-torque rotor on the port side of the tailboom.
Two turboshaft engines are located above the passenger cabin. In the prototypes
and initial production aircraft, these engines were Allison 250-C30s, a new
version of the popular Allison 250 engine developed specially for the S-76, with
a single-stage centrifugal compressor instead of the multi-stage
axial/centrifugal compressor of earlier models of the engine, rated at 650 shp
(480 kW) for take-off. These engines are connected to the main rotor by the main
gearbox, a three-stage unit with a bull gear as its final stage rather than the
planetary gear used by previous generations of Sikorsky helicopters. This
arrangement gave 30% fewer parts and lower costs than a more conventional
design.

Specifications (Sikorsky S-76C++)

General characteristics
Crew: two
Capacity: seats 12–13
Length: 52 ft 6 in (16.00 m) from tip of main rotor to tip of tail rotor
Width: 10 ft 0 in (3.05 m) at horizontal stabilizer
Height: 14 ft 6 in (4.42 m) to tip of tail rotor
Empty weight: 7,005 lb (3,177 kg) in utility configuration
Gross weight: 11,700 lb (5,307 kg)
Fuel capacity: 281 US gallons (1,064 liters), with 50 or 102 US gallons (189 or
386 liters) available in extra auxiliary tanks
Powerplant: 2 × Turbomeca Arriel 2S2 turboshaft, 922 shp (688 kW) each
Main rotor diameter: 44 ft 0 in (13.41 m)

Performance
Maximum speed: 155 kn (178 mph; 287 km/h) at maximum takeoff weight at sea level
in standard atmospheric conditions
Cruise speed: 155 kn (178 mph; 287 km/h) maximum cruise speed is the same as
maximum speed
Range: 411 nmi (473 mi; 761 km) no reserves, at long-range cruise speed at 4,000
ft altitude
Service ceiling: 13,800 ft (4,200 m)

Avionics

Honeywell four-tube EFIS and Collins Proline II avionics suite
Four-axis fully coupled autopilot
Integrated Instrument Display System (IIDS)
Honeywell ground proximity warning system
Honeywell Primus weather radar
Dual comm/nav radios
Automatic direction finder
Dual attitude and heading reference system and air data computers
Radio altimeter
Mode C transponder
Dual VHF omnidirectional range (VOR) and Instrument landing system (ILS)
Distance measuring equipment
Cockpit voice recorder





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