Sikorsky H-19 Chickasaw (company model number S-55)

https://en.wikipedia.org/wiki/Sikorsky_H-19_Chickasaw

he Sikorsky H-19 Chickasaw (company model number S-55) was a multi-purpose
helicopter used by the United States Army and United States Air Force. It was
also license-built by Westland Aircraft as the Westland Whirlwind in the United
Kingdom. United States Navy and United States Coast Guard models were designated
HO4S, while those of the U.S. Marine Corps were designated HRS. In 1962, the
U.S. Navy, U.S. Coast Guard and U.S. Marine Corps versions were all redesignated
as H-19s like their U.S. Army and U.S. Air Force counterparts.

Development of the H-19 was initiated privately by Sikorsky without government
sponsorship. The helicopter was initially designed as a testbed for several
novel design concepts intended to provide greater load-carrying ability in
combination with easy maintenance. Under the leadership of designer Edward F.
Katzenberger, a mockup was designed and fabricated in less than one year.

The first customer was the United States Air Force, which ordered five YH-19
aircraft for evaluation; the YH-19's first flight was on 10 November 1949, less
than a year after the program start date. This was followed by delivery of the
first YH-19 to the U.S. Air Force on 16 April 1950 and delivery of the first
HO4S-1 helicopter to the U. S. Navy on 31 August 1950. A U.S. Air Force YH-19
was sent to Korea for service trials in March 1951, where it was joined by a
second YH-19 in September 1951. On 27 April 1951, the first HRS-1 was delivered
to the U.S. Marine Corps, and on 2 May 1951, the first S-55 was delivered to
Westland Aircraft.

1,281 of the helicopters were manufactured by Sikorsky in the United States. An
additional 447 were manufactured by licensees of the helicopter including
Westland Aircraft, the SNCASE in France and Mitsubishi in Japan.

The helicopter was widely exported, used by many other nations, including
Portugal, Greece, Israel, Chile, South Africa, Denmark and Turkey.

In 1954 the Marines tested an idea to enhance lift in hot and high and/or
heavily loaded conditions by installing a rocket nozzle at the tip of each rotor
blade with the fuel tank located in the center above the rotor blade hub. Enough
fuel was provided for seven minutes of operation. Although tests of the system
were considered successful, it was never adopted operationally.

The YH-19 prototypes featured a blunt aft fuselage and a single
starboard-mounted horizontal tailplane with a small vertical fin at its outboard
end. Initial production models added a large fillet-like fin behind the fuselage
and under the tailboom, and the tailplane configuration was changed to an
inverted "V" shape.

Early H-19 and HO4S variants were powered by a Pratt & Whitney R-1340-57 radial
rated at 600 hp (472 kW) and used a centrifugal clutch that automatically
engaged the main rotor when a preset engine speed was reached. However, the HO4S
was deemed underpowered in U.S. Navy service with this powerplant, so the
aircraft was re-engined with a 700 hp (522 kW) Wright R-1300-3 radial which the
U.S. Navy found to be adequate in an air-sea rescue role; the H-19B, HO4S-3,
HRS-3, and subsequent models would use this powerplant. The R-1300 models also
used a single horizontal tailplane in place of the early inverted "V" style, and
a new hydro-mechanical clutch gave smoother and more rapid rotor acceleration
during clutch engagement and allowed the engine to be started and operated at
any speed while disengaged from the transmission and rotors.

Early civilian and military S-55 models offered a folding 400 lb (181 kg)
capacity hoist above the starboard main cabin door, while later models could be
equipped with a more capable and reliable 600 lb (272 kg) capacity unit.
Starting with the introduction of the S-55C in October 1956, the tailboom was
inclined three degrees downward to provide more main rotor clearance during hard
landings; models equipped with the inclined tail also used an 8 ft 9 in (2.67 m)
tail rotor in place of the earlier 8 ft 8 in (2.64 m) unit.


Role
Utility helicopter

Manufacturer
Sikorsky

Designer
Edward F. Katzenberger

First flight
10 November 1949

Introduction
16 April 1950 (U.S. Air Force)

Retired
26 February 1969 (U.S. Navy)

Number built
1,728

Variants
Westland Whirlwind

Developed into
Sikorsky H-34

The H-19 Chickasaw holds the distinction of being the U.S. Army's first true
transport helicopter and, as such, played an important role in the initial
formulation of Army doctrine regarding air mobility and the battlefield
employment of troop-carrying helicopters. The H-19 underwent live service tests
in the hands of the 6th Transportation Company, during the Korean War beginning
in 1951 as an unarmed transport helicopter. Undergoing tests such as medical
evacuation, tactical control and frontline cargo support, the helicopter
succeeded admirably in surpassing the capabilities of the H-5 Dragonfly which
had been used throughout the war by the Army.

The U.S. Marine Corps made extensive use of the H-19 in the Korean War. It was
designated as the HRS in USMC service. Marine Squadron HMR-161 arrived in Korea
on September 2, 1951 with 15 HRS-1 helicopters. The new helicopter squadron
started operations upon arrival. On September 13, 1951, during Operation
Windmill I, HMR-161 transported 18,848 pounds of gear and 74 Marines onto a
ridge in the Punchbowl area. A week later HMR-161 shuttled 224 recon company
marines and 17,772 pounds of supplies to a remote hilltop in the same area.
Their performance continued to improve and in Operation Haylift II in February
23-27, 1953, HMR-161 lifted 1.6 million pounds of cargo to resupply two
regiments. Although HMR-161 helicopters were operating in hot landing zones they
did not lose any helicopters to enemy fire. HRS-1 helicopters were also used to
relocate rocket launcher batteries. Because rockets create much visible dust
when fired they make an easy target for enemy artillery. To reduce their
exposure, launchers and crews were moved twice a day. Each HRS-1 helicopter
carried four rocket launchers and extra rockets as external cargo, with the crew
in the cabin. The HRS-1 helicopter proved to be durable and reliable in Korean
service. One reportedly flew home after losing 18 in (46 cm) of main rotor blade
to a tree. HMR-161 reported 90% aircraft availability.

The U.S. Air Force ordered 50 H-19A's for rescue duties in 1951. These aircraft
were the primary rescue and medical evacuation helicopters for the USAF during
the Korean War. The Air Force continued to use the H-19 through the 1960s,
ultimately acquiring 270 of the H-19B model.

On 1 September 1953, Sabena used the S-55 to inaugurate the first commercial
helicopter service in Europe, with routes between Rotterdam and Maastricht in
the Netherlands and Cologne and Bonn in Germany.

The H-19 was also used by the French forces in the First Indochina War. A small
number of war-worn H-19s were given to the Republic of Vietnam Air Force in
1958, when the French military departed. These saw very limited service in the
early days of the Vietnam War, before being supplanted by the more capable
Sikorsky H-34 Choctaw.

The H-19 left U.S. military service when the CH-19E was retired by U.S. Navy
squadron HC-5 on 26 February 1969. Surplus H-19s were sold on the open market,
and civil interest was sufficient that Sikorsky (and later Orlando Helicopter
Airways) offered conversion kits allowing a military surplus H-19 to be
commercially operated under a standard Federal Aviation Administration type
certificate as an S-55B. Turboshaft conversions and a novel campervan-like
"Heli-Camper" conversion—featuring a built-in mini-kitchen and sleeping
accommodations for four—were also offered by aftermarket modification companies.

Specifications (UH-19C)

General characteristics
Crew: 2
Capacity: ten troops or eight stretchers
Length: 42 ft 2 in (12.85 m) fuselage length excluding tail and main rotors ;
(UH-19D 42 ft 3 in (12.88 m))
Height: 13 ft 4 in (4.06 m)
Empty weight: 4,795 lb (2,175 kg) (UH-19D 5,250 lb (2,380 kg))
Gross weight: 7,500 lb (3,402 kg) (UH-19D 7,900 lb (3,600 kg))
Powerplant: 1 × Pratt & Whitney R-1340-57 9-cylinder air-cooled radial piston
engine, 600 hp (450 kW)

(UH-19D Wright R-1300-3 Cyclone 7-cylinder air-cooled radial piston engine, 700
hp (520 kW))Main rotor diameter: 53 ft (16 m)
Main rotor area: 2,206 sq ft (204.9 m2)

Tail rotor diameter: 8 ft 8 in (2.64 m)

Performance
Maximum speed: 101 mph (163 km/h, 88 kn) (UH-19D 112 mph (97 kn; 180 km/h))
Cruise speed: 85 mph (137 km/h, 74 kn) (UH-19D 91 mph (79 kn; 146 km/h))
Range: 450 mi (720 km, 390 nmi) (UH-19D 385 mi (335 nmi; 620 km))
Service ceiling: 10,500 ft (3,200 m) (UH-19D12,500 ft (3,800 m))

Armament

None normally fitted ; H-19s used for armament tests at Fort Rucker were
experimentally equipped with a variety of automatic weapons and rockets. H-19s
in Southeast Asia were sometimes equipped with door-mounted .30 in (7.62 mm) or
..50 in (12.70 mm) calibre machine-guns for self-defence and suppression of enemy
fire near landing zones.



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