Nederlandse Modelbouw en Luchtvaartsite

Dutch Modelling and Aviation

In Memoriam

Klaas Willem Jonker
† April 30, 2018

On Monday 30 April 2018, Wilko Jonker died after a long illness at the age of 58. He leaves behind a wife and two children. The Dutch military aviation and plastic modeling were his hobby and on this website he shared all the knowledge he has collected over the years. His hobby has been able to distract him from the persistent disease in his body until the last week of his life. The contacts with other hobbyists were a major support for him.

This website will be maintained by different people for as long as possible, so that other enthusiasts can continue to benefit from extensive content.

Sikorsky SH-34J/UH-34J


This model was developed based on specifications of the US Navy from 1952, drawn up for a larger successor to the Sikorsky H04S-3 (Sikorsky S.55). These had also to be suitable for anti-submarine warfare.
The contract for the construction of the prototype, equipped with a Wright R-1820 radial engine of 1137 kW was received in June 1952.
The first flight was made in March 1954 had and the new helicopter had received the designation XHSS-1.
The first production machine was its first flight on September 24, 1954.

The production version HSS-1 Seabat, equipped with "dunking sonar" and ASW equipment, first flew in August 1955 and was operational in August 1955.
The HSS-1N (SH-34J) was suited for night operations and for use in bad weather and was equipped with Doppler Navigation; automatic stabilization and ditto hoover possibility.

In January 1957, the only HSS-1F equipped with two General Electric T58 turbine engines, made its first flight.
HSS-1 / SH-34 and HSS-1N / SH-34J Seabats which were stripped of their ASW equipment were later designated as UH-34G, respectively UH-34J.

In 1962 the multiplicity of type definitions was standardized in the uniform DoD marking system.
The HSS-1 was designated as SH-34G. The HSS-1N received the designation SH-34J.

The United States Marine Corps in October 1954 placed an order for the HUS-1 Seahorse, which could carry 12 marines. This enter service in February 1957.
Four examples were adapted for use in the Arctic and were designated as HUS-1L (LH-34D)
Some HUS-1 aircraft were equipped with an inflatable float system and designated as HUS-1A.

The US Coast Guard also used a number of examples in use as HUS-1G.
After 1962 these were designated as UH-34D respectively UF-34E.

One HUS-1 was borrowed by the United States Army for evaluation purposes and in 1955 the United States Army ordered the utility transport version, H-34 Choctaw which could carry 16 men. 500 examples were delivered. From 1962 and on these were referred to as CH-34A and CH-34C and differed only in equipment.
In April 1955, the first of 437 new H-34A's entered service.
Later, another 21 HUS-1 were taken from the United States Marine Corps and these were designated H-34A.

The H-34A was the first helicopter safe enough for regular use by the US President.
  For this purpose the US Army established in 1957 the Executive Flight Detachment equipped with adapted Choctaws. These aircraft, designated VH-34A, were equipped with sound insulation, luxurious VIP interior design and modern communications equipment.

In 1960 followed a modification program for the H34A and B versions of the USAF and U.S. Army in order to standardize both types to H-34C.
Added were automatic flight stabilization and other improvements.
After 1962, about 190 H-34Cs and 179 H-34As were in use, these were designated as CH-34C and CH-34B. Some were later converted to VH-34C.

The H-34 was also built under license by Sud-Aviation which 110 units built for France plus another nine examples for Belgium.
Also Westland achieved the licensing rights in 1956 and developed the Wessex, a turbine version. Sikorsky continued to build the original version with radial engine.
Only in January 1970 Sikorsky announced conversion kits for retrofitting with the Pratt & Whitney PT6 Twin-Pac turbine engine. The first flight of the S-58T was on August 19, 1970.
The type certification was granted in April 1971.
Sikorsky built 153 conversion kits, until California Helicopter International bought the rights in 1981. Later also offered Orlando Helicopters conversions for the S-58.

The civilian S-58B and S-58D were passengers and freighter versions, and similar to their military counterparts. The S-58B could carry 12 passengers.
Until the end of production in January 1970 were 1820 examples built by Sikorsky in several versions.


XHSS-1 Seabat:
Three Sikorsky S-58s for evaluation by the  U.S. Navy, later designated as YHSS-1 and from 1962 as YSH-34G.
HSS-1 Seabat:
anti sub version for the U.S. Navy. From 1962 amd on designated as SH-34G; 215 examples built.
  • HSS-1F Seabat: One HSS-1 for research purposes equipped with two YT-58-GE; from 1962 and on designated as SH-34H.
HUS-1 Seahorse:
transport version of the HSS-1 for the U.S. Marine Corps, from 1962 and on designated as UH-34D, 462 examples built.
  • UH-34D: designation of HUS-1 after 1962; 54 examples new built.
  • HUS-1A Seahorse: 40 examples of HUS-1s equipped with floats, from 1962 and on designated as UH-34E.
  • HUS-1G Seahorse: Version of the HUS-1 for the  US Coast Guard, from 1962 and on designated as HH-34F; six examples built.
  • HUS-1L Seahorse: Four modified HUS-1s for used under polar conditions, from 1962 and on designated as LH-34D.
  • HUS-1Z Seahorse: Seven modified HUS-1s with VIP interior to be used by the  Executive Flight Detachment, from 1962 and on designated asVH-34D.
YHSS-1N Seabat:
Prototype of a modified HSS-1, from 1962 and on designated as YSH-34J.
HSS-1N Seabat:
Night- and bad weather version of the HSS-1 with improved avionics and autopilot, from 1962 and on designated as SH-34J, 167 examples built.
  • UH-34J: Stripped version of the SH-34J, al ASW equipment removed and used for training and transport .
  • HH-34J: Ex-USN UH-34Js used by the U.S. Air Force.
  • VH-34J: VIP version of the SH-34J.
U.S. Army version of the HSS-1 with a 1525 hp Wright R-1820-84, from 1962 and on designated as CH-34A; 359 examples built  plus 21 HUS-1 originating from U.S. Navy.
  • JH-34A: H-34A used for weapon tests.
  • VH-34A: VIP version of the H-34A.
H-34A conversion with minor changes; from 1962 and on designated as CH-34B.
version of H-34B with minor changes and converted H-34A; from 1962 and on designated as CH-34C.
  • JH-34C: CH-34C used for weapon tests.
  • VH-34C: VIP version of the CH-34C.
designation for aircraft with USAF serials, delivered under MAP and MDAP conditions to other countries.
commercial version of the basic transport version.
commercial version of the improved transport version.
Commercial passengers and transport version.
Commercial passengers and transport version
Commercial conversion with turbine engines: kits produced by Sikorsky, Orlando Helicopter and California Helicopter.


Technical information
Length with rotor 14,25 m Rotor diameter: 17,27 m
Height: 4,36 m Tail Rotor diameter: - m
Empty weight: 3754 kg Full weight: 5900 kg
Max. speed: 196 km/hr Cruising speed: 158 km/hr
Range: 400 km Service ceiling: 3500 m
Engine type: One Pratt & Whitney R-1830-43 Twin Wasp rated 1200 hp
Crew: Four

SH-34J: one torpedo

UH-34J: none