Sikorsky S-52

https://en.wikipedia.org/wiki/Sikorsky_S-52

The Sikorsky S-52 was a utility helicopter developed by Sikorsky Aircraft in the
late 1940s. It was used by the U.S. Navy, Marines, and Coast Guard. The S-52 was
the first US helicopter with all-metal rotor blades. A two-seater, it was
developed into the four-seat S-52-2. It was designated HO5S-1 by the U.S. Navy
and Marine Corps; HO5S-1G by the Coast Guard; and YH-18A by the Army.

Sikorsky Aircraft began designing the S-52 in late 1945. The prototype S-52,
first flown in 1947, was a two-seater and used a 178 hp (133 kW) Franklin
air-cooled flat-six piston engine.

The two-seat version was modified into the S-52-2, a four-seat helicopter using
a 245 hp (183 kW) Franklin O-425-1 air-cooled flat-six. It had a semi-monocoque
fuselage of pod-and-boom arrangement with a large bubble-like front greenhouse,
a three-blade rotor, and quadricycle fixed landing gear. The production S-52-3
(HO5S-1) incorporated a downward sloping (anhedral) v-tail stabilizer. It also
had sliding doors on the right forward and left rear sides, and a vertically
split front bubble, allowing the left half to swing open in a clamshell fashion.
The engine was placed at the aft end of the cabin and was canted forward 30
degrees to couple with the clutch and transmission. The pilot-in-command
occupied the right front seat.

The first American helicopter to have all-metal rotor blades, the prototype set
several speed and height records in 1948, including 129.6 mph (204.2 km/h) on a
3 km (2 mi) course, 122.75 mph (197.54 km/h) on a 1 km (1,100 yd) circuit, and
an absolute height of 21,220 ft (6,468 m). It was capable of hover out of ground
effect at 5,900 ft (1,798 m) or 9,200 ft (2,804 m) in ground effect. The S-52 is
widely believed to be the first helicopter to be looped, as flown by Harold E.
Thompson in 1949.

The S-52 also served as the basis of the turbine-powered S-59, which as the
XH-39, competed for and lost the contract that produced the Bell UH-1 Iroquois.
This aircraft differed in having a four-bladed rotor (against the S-52's three)
and retractable tricycle gear.


Role
Helicopter

Manufacturer
Sikorsky Aircraft

First flight
12 February 1947

Introduction
April 1951

Primary users
United States Navy
United States Army
United States Marine Corps
United States Coast Guard

Number built
93

Variants
Sikorsky XH-39
Vertical Hummingbird

The Navy operated the aircraft as a utility type, and it was used by the Marines
for observation and scouting in Korea, where the HO3S proved more popular. Four
S-52s were evaluated by the United States Army for utility use in 1950, as the
YH-18A, but not purchased in quantity.

Many of the former military HO5S-1 units were demilitarized, rebuilt, and
licensed as civil aircraft by Orlando Helicopters, who acquired the parts
inventory from Sikorsky.

Specifications

General characteristics
Crew: two
Capacity: two passengers or two stretchers
Length: 27 ft 5 in (8.36 m) (fuselage length)
Height: 8 ft 8 in (2.64 m)
Empty weight: 1,650 lb (748 kg)
Gross weight: 2,400 lb (1,089 kg)
Max takeoff weight: 2,700 lb (1,225 kg) (overload)
Fuel capacity: 62 US gal (230 l; 52 imp gal)
Powerplant: 1 × Franklin 6V6-245-B16F air-cooled six-cylinder
horizontally-opposed piston engine, 245 hp (183 kW)
Main rotor diameter: 33 ft 0 in (10.06 m)
Main rotor area: 855 sq ft (79.4 m2)

Performance
Maximum speed: 110 mph (177 km/h; 96 kn) at sea level
Cruise speed: 96 mph (154 km/h; 83 kn)
Range: 415 mi (361 nmi; 668 km)
Service ceiling: 15,500 ft (4,700 m)
Rate of climb: 1,300 ft/min (6.6 m/s)




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