Sikorsky H-19/S-55 Chickasaw

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

The 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.

Major innovations implemented on the H-19 were the forward placement of the
engine below the crew compartment and in front of the main cabin, the use of
offset flapping hinges located nine inches (229 mm) from the center of the
rotor, and the use of hydraulic servos for the main rotor controls. These
features yielded an aircraft that was far more capable in a transport role than
previous Sikorsky designs.

Locating the engine forward allowed the main cabin to be located essentially in
line with the main rotor's rotational axis and close to the aircraft center of
gravity, making it easier to maintain proper weight and balance under differing
loading conditions. The impetus for this design choice was the recent rejection
of the Sikorsky XHJS by the U.S. Navy in favor of the tandem rotor Piasecki HUP
Retriever; the Navy had strongly objected to the necessity to use ballast in the
cabin-forward XHJS to maintain proper weight and balance, prompting Sikorsky to
seek single-rotor design alternatives that did not require this.


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 US 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. 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.

Specifications (H-19C)

General characteristics
Crew: two (pilot, copilot)
Capacity: ten troops or eight stretchers
Length: 42 ft 4 in (12.91 m)
Rotor diameter: 53 ft (16.16 m)
Height: 13 ft 4 in (4.07 m)
Disc area: 2206 sq ft (205 m2)
Empty weight: 4,795 lb (2,177 kg)
Loaded weight: 7,500 lb (3,409 kg)
Powerplant: 1 × Pratt & Whitney R-1340-57 radial engine, 600 hp (450 kW)

Performance
Maximum speed: 101 mph (88 knots, 163 km/h)
Cruise speed: 85 mph (74 knots, 137 km/h)
Range: 450 mi (391 nmi, 725 km)
Service ceiling: 10,500 ft (3,200 m)




*