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Bell HSL

The Bell HSL (Model 61) was a 1950s American anti-submarine warfare (ASW) helicopter manufactured by Bell Helicopter, featuring a unique tandem rotor design.

It conducted its maiden flight in 1953 and was adopted by the U.S. Navy in 1957.

Despite producing over 50 units, the helicopter was phased out by 1960 due to rapid advancements in helicopter technology during that era.

The helicopter was equipped with two main rotors positioned at each end of the fuselage tube, connected by a transmission system, and powered by a single Pratt & Whitney R-2800-50m 18-cylinder air-cooled radial engine.

Interestingly, the front rotor shaft was slightly positioned ahead of the pilots in the front cockpit.

The initial flight of the prototype Bell Model 61 took place on March 3, 1953, as it was specifically created to fulfil a need for an anti-submarine warfare helicopter by the United States Navy.

By June 1950, the Model 61 was declared the victor of the competition, leading to the procurement of three XHSL-1 evaluation aircraft.

Featuring a rectangular-section fuselage structure and a four-leg, six-wheel landing gear, the Model 61 was equipped with a Pratt & Whitney R-2800 radial engine situated in the aft fuselage.

The crew consisted of two pilots and two sonar operators.

Due to the pressing need, low-rate production commenced shortly after Bell secured a contract for three XHSL-1s.

The Navy later expanded the contract to include a minimum of 160 production aircraft, with 18 designated for the British Royal Navy.

A total of 234 bureau numbers were allocated.

However, due to development challenges leading to delays in meeting contract deadlines, only 50 aircraft were actually manufactured.

Despite all units being delivered, only a few were utilised after passing service tests and being accepted, primarily for airborne mine sweeping development.

The remaining aircraft were sent directly to storage and eventually decommissioned.

The HSLs were not employed for operational purposes.

Seven of them were allocated to the U.S. Naval Air Mine Defence Unit in Panama City, Florida, to assist in the development of airborne minesweeping.

The first one arrived in September 1956, and the last one was decommissioned in early 1960.

Variants

XHSL-1

Two experimental flight test and one static test article

HSL-1

Production version, 50 built.

Bell Model 61

Company designation for the HSL

Specifications

HSL-1

Crew

4 (search mission),

3 (attack mission)
Capacity

Hoist capacity

800 lb (363 kg)

Length

39 ft 11 in (12.17 m) (fuselage only)

Width

11 ft 6 in (3.5 m) (rotors folded)

Height

14 ft 6 in (4.42 m)

Empty weight

13,073 lb (5,930 kg)

Gross weight

16,958 lb (7,692 kg) (search mission)

16,853 lb (7,644 kg) (attack mission)

Max take-off weight

26,500 lb (12,020 kg)

Fuel capacity

450 US gal (375 imp gal; 1,703 L) maximum

Powerplant

1 × Pratt & Whitney R-2800-50 18-cyl.

Two-row air-cooled radial piston engine,

2,100 hp (1,600 kW) for sea level take-off at 2,600 rpm

Normal power at sea level,

1,900 hp (1,417 kW) at 2,400 rpm

Main rotor diameter

2 × 51 ft 6 in (15.70 m)

Main rotor area

3,840 sq ft (357 m2)

Blade section

NACA 0015

Performance

Maximum speed

124 mph (200 km/h, 108 kn) (search mission)

Cruise speed

96 mph (154 km/h, 83 kn) at 1,500 ft (457 m)

Range

350 mi (560 km, 300 nmi)

Combat range

140 mi (230 km, 120 nmi)

Endurance

3 hours, 30 minutes of loitering on search mission

Service ceiling

14,400 ft (4,400 m) at take-off weight with normal power

Absolute hover ceiling OGE

10,750 ft (3,277 m)

Rate of climb

1,475 ft/min (7.49 m/s) normal power, sea level, at take-off weight in forward flight

1,200 ft/min (6.1 m/s) in vertical flight with take-off power, sea level, at take-off weight in forward flight

Armament

Bombs

2x Mark 43 torpedoes

Avionics

Dipping Sonar

Sources

Bell Aircraft Since 1935-A J Pelletier.

bellflight.com

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