Back Sikorsky S-58 / HSS "Seabat" / HUS "Seahorse" / CH-34 "Choctaw"
1954

Sikorsky S-58

The first prototype of this widely used helicopter was designed to meet a 1952 requirement of the U.S. Navy for a larger and more up-to-date helicopter to replace the S-55 on anti-submarine patrol work. Designated XHSS-1, it flew for the first time on 8 March 1954, since when some eighteen hundred have been built for service in many parts of the world. The first production HSS-1 flew on 20 September 1954, and the type became operational in August 1955. Now designated SH-34G, it has the name Seabat and carries either dunking sonar search equipment or weapons for attacking submarines. Later Seabats are the SH-34J (previously HSS-1N) with automatic stabilisation and some equipment improvements, and the 'winterised' LH-34D (formerly HSS-1L). Examples of these three models are still in U.S. Navy service, although since their replacement by the SH-3 Sea King began, many have been converted to utility transports with UH prefixes.

The U.S. Marine Corps, with whom the S-58 is known as the Seahorse, have used the type since 1957 primarily for utility transport and for recovery duties connected with the U.S. satellite programme. The 12-passenger UH-34D and UH-34E (formerly HUS-1 and HUS-1A) are basically alike, the latter being an amphibious version with pontoons for landing on water. The VH-34D is a VIP transport. Army S-58's have the name Choctaw, the CH-34A and CH-34C differing only in the equipment carried, and have been in service since April 1955 as 16-seat transports or crane helicopters. Substantial numbers of military S-58 variants have been exported, and in mid-1967 were serving with the Federal German Army (one hundred and forty-four); the navies of Argentina (five), Brazil (five), France (twenty-six), Germany, Indonesia, Italy (eighteen), Japan (fourteen) and the Netherlands (twelve); and the air forces of Belgium (nine), Cambodia (three), Canada (four), France (one hundred and ten), Germany, Israel (twelve), Thailand (twenty) and South Vietnam (sixty). Those in French and Belgian service were manufactured in France by Sud-Aviation.

The commercial S-58B and S-58D are passenger/cargo transport helicopters comparable with their military counterparts. The 12-seat airline version, certificated by the FAA in August 1956, was built for Chicago Helicopter Airways (eight), New York Airways (three) and Sabena (eight). Production of the S-58 ended in December 1965 after one thousand seven hundred and sixty-six had been built by Sikorsky, but has since started again to fulfil additional U.S. orders and one from the Italian Navy for six SH-34J's. The turbine-engined development still being produced by Westland as the Wessex is described separately.

K.Munson "Helicopters And Other Rotorcraft Since 1907", 1968

Sikorsky S-58

Another winner for Sikorsky in the fifties was the Model S-58. The prototype was developed to meet a US Navy specification for a more advanced antisubmarine helicopter than the S-55. Designated XHSS-1, it first flew on 8 March 1954 and the first production aircraft, nicknamed "Seabat", was ready by September. The Marine Corps adopted it in 1957 as "Seahorse" and the Army in 1955 as "Choctaw". As a transport helicopter capable of carrying 18 combat equipped troops or a 1350kg load, the Choctaw was widely used in Vietnam. The Marines received about 500 of the S-58 in the utility version (HUS-1 and -1A).

In 1956, Westland acquired the license to build the S-58 and developed a turbine-engined version called the Wessex. Sikorsky continued producing the S-58 with the Wright radial engine; a turbine-powered conversion with a PT6T-6 Twin Pack did not become available until 1970.

G.Apostolo "The Illustrated Encyclopedia of Helicopters", 1984

Sikorsky S-58

The H-34 was originally developed to meet a Navy requirement for a single-engined medium helicopter that could replace the Sikorsky HO4S (S-55 / H-19) in the anti-submarine warfare (ASW) role. Designated the Model S-58 by Sikorsky and XHSS-1 by the Navy, the new aircraft incorporated several features that had first appeared on the S-55, including a nose-mounted engine and a cockpit located above and slightly forward of a spacious, box-like passenger/cargo compartment. However, the S-58 was larger and heavier than its predecessor, with a more powerful 1525hp engine and a completely redesigned, downward-sloping tail section. The S-58 also differed from the S-55 in having larger-diameter, four-bladed main and tail rotors and three-point, tail-wheel landing gear.

The prototype XHSS-1 made its first flight in March 1954, and the type entered regular Navy service in August 1955 as the HSS Seabat. A troop transport variant was simultaneously acquired by the Marine Corps as the HUS Seahorse, and one example of this type was loaned to the Army for service test and evaluation. The Army had placed preliminary orders for production H-34A troop transport variants of the Navy XHSS-1 in April 1953 and the performance of the borrowed Marine Seahorse, which was essentially identical to the H-34 version, confirmed the Army's belief that the type would be a vast improvement over the H-19s then in service.

The Army accepted the first of 437 new-construction H-34As in April 1955; an additional twenty-one HUS-1 aircraft transferred from the Marine Corps during Fiscal Year 1955 were also designated H-34A (though at least five further USMC Seahorses operated by the Army between 1955 and 1957 retained their original Navy Bureau numbers). The H-34A's performance was, as hoped, markedly superior to that of the H-19, as evidenced by the fact that in 1956 an early production example flown by Army Captains Claude E. Hargett and Ellis Hill set new world helicopter speed records on courses of 100, 500 and 1000km. The H-34A was also the first helicopter judged safe enough for routine use by the U.S. President, and in 1957 the Army organized an Executive Flight Detachment equipped with specially modified Choctaws. These aircraft were fitted with extensive soundproofing, plush VIP interiors, and upgraded communications equipment, and were designated VH-34A.

In 1960 Sikorsky began modifying Army H-34As (and Air Force H-34As and -Bs) to -C model standard through the addition of automatic flight stabilization systems and other detail changes. By January 1962 the Army had 190 H-34Cs and 179 H-34As in its inventory; under the Tri-Service designation system introduced later that year the aircraft were redesignated as, respectively, CH-34C and CH-34B. Several -C model aircraft were subsequently modified to VH-34C standard for VIP transport duties.

Though the CH-34 was arguably the most capable Army transport helicopter of the early 1960s (prior to the widespread introduction of the UH-1 Iroquois), it did not see extensive Army service in Vietnam. The Army's 1962 decision to deploy the Vertol CH-21 Shawnee to Southeast Asia instead of the faster and more capable Choctaw was based on two considerations. First, in accordance with then-current Army doctrine regarding the area-standardization of aircraft types, the CH-21 was already widely deployed in the Pacific area and the continental United States, whereas all but about thirty of the Army's CH-34s were based in western Europe. It was therefore logical and logistically preferable that the CH-21, which was considered acceptable if somewhat past its prime, should be chosen for deployment to Southeast Asia. The Army's second reason for sending the Shawnee rather than the Choctaw was a somewhat negative opinion of the Choctaw's combat survivability, a belief based on French experience in North Africa. French forces had used both the CH-21 and the CH-34 in Algeria, the former flown by the Army and Air Force and the latter by the Navy, and official evaluations had indicated that the Shawnee was more likely to survive multiple hits by ground fire than was the CH-34. The French belief that the location and 'fragile' construction of the Choctaw's fuel tanks made the craft extremely vulnerable to ground fire seemed to validate the U.S. Army's decision to deploy the Shawnee to Vietnam pending the introduction into widespread service of the UH-1 Iroquois. The approximately twenty Army H-34s that did eventually reach Vietnam proved no more vulnerable than any other aircraft in the theatre, however, and ably carried out issions ranging from combat assault to aeromedical evacuation and general cargo transport. Most of these twenty aircraft were turned over to the South Vietnamese during the course of the war, though a few were ultimately reclaimed by the Army prior to the final collapse of the Saigon Government.

The CH-34 Choctaw remained in frontline Army service well into the late 1960s, and was standard equipment in many Army Reserve and National Guard aviation units for considerably longer. Indeed, the last Choctaw was not officially retired until the early 1970s, by which time the type's duties had been divided between the UH-1H Iroquois and the CH-47 Chinook.

S.Harding "U.S.Army Aircraft since 1947", 1990

Sikorsky S-58 / HSS "Seabat" / HUS "Seahorse" / CH-34 "Choctaw"

Designed to overcome the range and offensive payload deficiencies of the anti-submarine HO4S version of the S-55, the Sikorsky S-58 was developed to a US Navy order for a prototype XHSS-1 placed on 30 June 1952. The nose engine position was retained for the 1137kW Wright R-1820 engine, but a completely new fuselage, four-bladed main and tail rotors, and transmission system were introduced, together with main rotor and rear fuselage folding to facilitate shipboard stowage. The prototype flew on 8 March 1954, followed by the first production HSS-1 Seabat (later SH-34G) on 20 September, and the type began to reach anti-submarine squadrons in August 1955. The HSS-1N (SH-34J) was developed for night operations, equipped with Doppler for navigation, automatic stabilisation and automatic hover coupler, while a single HSS-1F (SH-34H) flown on 30 January 1957, was powered by two General Electric T58 turboshafts. In 1960 five HSS-1Z (VH-34D) helicopters joined the Executive Flight Detachment for Presidential and VIP transport duties. Seabats stripped of ASW equipment for utility duties were designated UH-34G and UH-34J.

The US Marine Corps ordered the HUS-1 Seahorse (UH-34D) version on 15 October 1954; able to carry 12 Marines, this variant entered service in February 1957. Four HUS-1L (LH-34D) helicopters were modified for operation in the Arctic, while inflatable flotation gear identified the US Marines' HUS-1A (UH-34E) and the US Coast Guard's HUS-1G (HH-34F). The US Army ordered several hundred H-34A, H-34B and H-34C Choctaw helicopters powered by 1063kW R-1820-84 engines and each carrying 16 troops or eight stretchers in the medevac role, the first unit being equipped in September 1955. The type was exported widely and built under licence in France and the UK, the turbine-powered Westland product known as the Wessex. In April 1971 Sikorsky received FAA approval for the S-58T PT6A Twin Pac-powered turbine conversion for H-34 airframes. One hundred and forty-six conversions, or conversion kits, were produced until, in 1981, the rights were sold to California Helicopter International. Since then customers for the California Helicopter (Sikorsky) S-58T included New York Airways, the Indonesian and South Korean air forces (now retired) and the government and air force of Thailand. The S-58T is also in service in Argentina with the Presidential Aircraft Squadron. Small numbers were built of S-58B and S-58D civil passenger and cargo transport helicopters, a 12-seat airline version being operated by Chicago Helicopter Airways, New York Airways and SABENA. When production was terminated in January 1970, Sikorsky had manufactured a total 1,820 S-58s of all versions.

In addition to the California Helicopters version, Orlando Helicopters also offers S-58 conversions. An S-58 Heli-Camper, similar in fit to the OHA-S-55 Heli-Camper is available, powered by a Wright Cyclone R-1820-84 engine. A further Orlando S-58T conversion is the Orlando Airliner, an 18-seat all-passenger version with nine additional tinted windows fitted on each side of the cabin. Thus far, nearly 30 conversions have been completed.

D.Donald "The Complete Encyclopedia of World Aircraft", 1997

Developed to meet US Navy specification for more advanced anti-submarine helicopter. Designated XHSS-1, it made its first flight 8 March 1954; first production aircraft, nicknamed Seabat, flew 20 September 1954. The army and navy versions were generally similar, differing mainly in equipment and fuel capacity. Westland acquired licence to build S-58 in the UK in 1956 and developed turbine version under name of Wessex. Total of 166 also produced under licence by Sud-Aviation in France. First commercial deliveries of S-58C made in 1956-57. In January 1970, Sikorsky announced the design of kits for the conversion to turbine power by the installation of the Pratt & Whitney PT6 Twin-Pac. First flight of the S-58T took place 19 August 1970; FAA certification awarded April 1971. Total of 153 conversion kits manufactured by Sikorsky, but exclusive rights acquired by California Helicopter International in 1981.

VERSIONS

CH-34A/H-34A Choctaw: Transport and general purpose helicopter for US Army.

CH-34C (formerly H-34C) Choctaw: Similar to CH-34A, but with airborne search equipment.

LH-34D (HSS-1L) : Winterised version of Navy Seabat.

SH-34G (HSS-1) Seabat: Anti-submarine version ordered by US Navy 30 June 1952; accepted for service in February 1954.

SH-34J (HSS-1N) Seabat: Improved version of SH-34G.

UH-34D (HUS-1) Seahorse: Utility version for Marines; ordered 15 October 1954 and accepted for service January 1957.

UH-34E (HUS-1A) Seahorse: Version with pontoons for emergency operation from water.

VH-34D (HUS-1Z) : VIP transport version of Seahorse.

S-58B: Commercial passenger/freighter version.

S-58C: Commercial passenger-carrying version with two doors on starboard side of cabin.

Description applies to this version except where indicated.

S-58D: Commercial passenger/freighter version.

S-58T: Turbine conversion with Pratt & Whitney PT6 Twin-Pac, comprising two PT6 engines and combining gearbox; improved performance includes greater speed and lifting power, and better hot-and-high operation.

Westland Wessex: Licence-produced UK version.

CUSTOMERS: Sikorsky built 1,821 models, mostly for military customers, between 1954 and 1968; another 166 built by Sud-Aviation and 356 by Westland under licence.

DESIGN FEATURES: Four-blade all-metal main and tail rotors. Blades of main rotor interchangeable. Tail rotor has servo control. Main and tail rotor brakes.

FUSELAGE: Semi-monocoque structure.

LANDING GEAR: Conventional three-wheel undercarriage, with tailwheel at extreme rear of fuselage. Air-oil shock-absorber struts. Mainwheels have rotating struts to reduce drag and weight. Tailwheel is fully castoring and self-centring, with an anti-swivelling lock. Mainwheel tyres 11.00 x 12. Tailwheel tyre 6.00 x 6. Toe-operated mainwheel brakes. Track 3.66m. Wheelbase 8.75m.

POWER PLANT: One Wright R-1820-84 radial air-cooled engine, rated at 1,136kW for take-off (S-58C) or 1,342kW PT6T-3 Twin-Pac comprising two PT6 turboshaft engines side by side with combining gearbox. Engine is mounted behind large clamshell doors in nose of fuselage to allow complete accessibility from ground level. Fuel capacity is from 750 litres to 1,164 litres depending on model.

ACCOMMODATION: Pilot's compartment above main cabin seats two side by side with dual controls. Cabin normally seats 12 passengers. Up to eight stretchers can be carried. Sliding windows of pilot's compartment removable in an emergency. Cabin and cockpit air conditioned and soundproofed.

Jane's Helicopter Markets and Systems

*     *     *

FACTS AND FIGURES

- When he checked in for a Sabena S-58 flight, Igor Sikorsky was asked if his name was spelt like the helicopter's.

- US military designation changes in 1962 led to the HSS-1 becoming the SH-34G.

- 'Doughnut' bags could be fixed to the S-58 undercarriage to make it amphibious.

- US Army CH-34s maintained a constant patrol along the border of West Germany with Czechoslovakia and East Germany.

- The US Army-Marines Executive Flight Detachment used VH-34D aircraft.

- A total of 603 S-58s were delivered to the US Marines.


Technical data for Sikorsky S-58

Crew: 2, passengers: 12-18, engine: 1 x Wright R-1820 pistone engine, rated at 1137kW, main rotor diameter: 17.1m, length: 17.3m, height: 4.9m, take-off weight: 6350kg, empty weight: 3754kg, max speed: 198km/h, cruising speed: 158km/h, rate of climb: 5.6m/s, service ceiling: 2900m, range: 450km

Comments1-20 21-40 41-60
George Coleman, e-mail, 06.04.2008reply

I was a crewman in UH-34's at NAF Sigonella in 71-72. limited time in UH-2's. Looking for pictures of those aircraft, numbers 143950 and 145683 if possible

Donald Bailey, e-mail, 04.04.2008reply

I am the Donald Bailey who's comments are included above. I recently came across some photos of our HS-34G from Sigonella. I will be glad to E-mail them to you for inclusion in you web page. Please give me an address. The photos are legit and will not contain any viruses.

Don Bailey, 5244108

lxbfYeaa, e-mail, 14.03.2024 Donald Bailey

20

reply

XAVIER, e-mail, 18.02.2008reply

CAN ANY BODY HELPME IDENTYFING A CH-34A PARKED IN PUERTO RICO. IT USED TO BELONG TO THE ELECTRIC COMPANY (AEE) IN PR.
IS THERE A LIST ON THE WEB OF SURVEVING CH-34?
MANY THANKS

Richard, e-mail, 17.11.2007reply

Techincal information as I remember:
Our H34 was powered by an 1820-84c radial air cooled engine. Attached to the engine which was installed backwards in the aircraft was a giant cooling fan. Attached to that was a hyrdo-mechanical clutch assembly. A shaft continued upward to the main tranmission. When the engine truned 11.293 times, the rotor blades turned once. This was the primary function of the main gear box, to reduce the speed of the main rotors. Attached to the gearbox was the rotor head which consisted of a stationary star and a rotating star. These star assemblies transmitted blade change angles as input by the pilot. Three hydraulic actuators moved the star assemblies. The main rotor had droop stops as well as anti-flap stops. The droop stops prevented the blades from drooping down during shut down and hitting the tail assembly. The anti-flap stops prevented upward movement of the blades when stationery. These stops were actuated by centrifugal force as the rotor head rotated. As crewman we had to ensure that all these stops were out during engaging the rotors and in when dis-engaging the rotors. Out of the rear of the main transmission was another shaft which led to the tail rotor. It also had a disk brake for the rotor head with an efficiency of stopping the rotor heads in 20 seconds from a hovering RPM, (which is not that fast). Prior to the tail rotor shaft making its way out of the transmission compartment there was a belt driven oil cooler for the tranmission oil system. The shafts finally enter an intermediate gear box which changes the angle of drive upward toward the tail rotor. Changes in the tail rotor blades pitch was done by cables attached to the pilot's rudder pedals. Our model did not have a generator mounted on the engine, (as the SH-34's did), and ours was mounted on the main transmission.
To engage the rotors, after the engine has warmed up, the pilot turned on a hyrdaulic pump which forced hyrdaulic fluid into the hydro-mechanical clutch assembly. This fluid caused the rotor disk in the assembly to start to turn. Once a sufficient rotor RPM was reached, the pilot let off the throttle to idle and then brought it back up to speed. This now allowed centrifical force to engage the mechanical stops in the hyrdo-mechanical clutch. It was always necessary to shut off the hydraulic pump after mechanically engaging the rotors as it would make auto rotation impossible while the pump is running.
Pilot's controls consisted of a collective stick with a motorcycle type throttle at the end. Only the pilots stick had a starter button on it. The cyclic stick is what controlled the main rotor blade pitch to give the helo a direction of flight. The tail rotors were controlled by the rudder pedals. Keep in mind the physics of, "for every action there is an equal and opposite re-action", thusly the pilot had to use the rudder pedals to keep the main rotors from going one direction and the helo in oppos ...

Don Bailey, e-mail, 11.09.2007reply

I was an aircraft electrician on the (SH-34G) HSS-1 in HS-1 at NAS Key West from 1958 to 1961. After that I had the assignment of my life as the Plane Captain /SAR crewman at NAF Sigonella Sicily. Our first bird was 138464. We were told that we were getting a new Aircraft. It landed and to our surprise it was 138467. I also installed the first 'On Board'APU on the SH-34G. It was a Great aircraft and very reliable. Don Bailey 524-41-08 AE-2 /P-1 /AC. Funny how we can remember all of those old numbers.

Jerry, e-mail, 18.08.2007reply

I've got some photos of an old helo. Would you or your viewers be able to tell me more info on it? I think it's a Sikorsky S-58.

Richard, e-mail, 06.11.2007reply

We had 2 UH34's in VC-8, Roosevelt Roads, Puerto Rico and our primary mission was to recover target drones dropped by our DP2E's. These single jet engine drones were radio controlled and towed a target for pilot to practice gunnery. When the flight was over a giant parachute would open and it would descend into the ocean. When it finally hits the ocean, a 'wet switch' activates a small explosive in the parachute shroud and it is allowed to drop free of the drone, (most of the time). It was strictly a volunteer effort on our part to jump in and free it. (The Ryan Company donated a case of beer for every time we did it). 2 crewmen in the cabin, 1 for communication with the pilot while the other leaned out the door with a giant hook that was attached to the cargo sling of the helo. At times our wheels were in the water, so we had to be fast. Picking up one of those drones from the ocean was no strain on the H34 and as soon as the drone was out of the water and spun around facing into the wind, we were on our way home where we lowered the drone to some old tires. A crane was standing by to pick the drone up for a fresh water wash. As both a mechanic and aircrewman in the helo, we made sure everything was taken care of. We did not have any oil leaks, although the R-1820 burned about a gallon of oil during the flight. We only had one pilot and a crewman usually rode in the co-pilot's seat. There were times that the pilot would actually let us fly the helo on it's return trip. From Puerto Rico I moved to Pensacola Florida where we had H34's for SAR and once again I was a mechanic and crewman on the good old H34. It was a dependable aircraft which required very little maintenance other than a daily grease job on the rotor head. One of the bureau number was 145721 of one of our H34's in Puerto Rico.

Michael Krivensky, e-mail, 15.06.2007reply

If anyone has any pictures of the original CH-34 Executive Flight crew with LTC Howell please send it to me.

Phil, e-mail, 11.05.2007reply

Lots of good info here, but lacking in technical detail. It would be interesting and informative to see a drivetrain layout with a description. Same could be said for flight controls, landin gear, and rotor system.

Thor, e-mail, 29.04.2007reply

There is one here in Barra, Rio de Janeiro. I saw the Sea Horse but I didn't knew anything about it. It was bigger than I thought. Excelent and complete info about this helicopter. I only had seen in movies. Thank you, Thor

Jay, e-mail, 05.12.2006reply

The UH-34 was a good aircraft for its time. The R-1820 engine, though powerful for getting out of impossible landing zones, not only burned oil, it leaked it too. The best I heard was a half gallon of oil an hour. The worse was 2 gallons per hour. Now a days, the Environmental Protection Agency would require an impact statement for every landing this aircraft would make if it were still flying.
The aircraft had landing gear that was either called a Dog Leg or a Vee Leg, depending on when it was produced. It's easy to see the difference by looking.
It had a 24 volt system, but this was boosted at startup by a small gasoline engine (lawn mower type in the cabin) that turned a small generator. If the batt was good, the generator wasn't really needed.
The belly of the aircraft was a large series of rubber fuel cells, bolted together thru strutural walls. Fuel would flow easily thru this series of fuel cells, but if one of them began to leak, it was usually a bitch to find the source.
This engine burned 115 /145 Ava gas. Powerful, purple stuff.
After startup, the last thing done was to give the engine a final glance. Then close the clamshell doors and go flying. It was a good idea to do as once I saw avagas pouring down over a RUNNING engine. A fuel line leak in the engine section is very bad. Very bad indeed.
The need for changing a carburator on one of these engines caused a whole new section of the dictonary to be born. Words were used that had yet been defined, but you knew they were very bad words.
Cuss them and hate them if you want, but this was one aircraft that almost always got you home.

etienne, e-mail, 24.03.2007reply

Is it possible to know when it's last year in service, both for the Wessex and the sikorsky?
Thankyou

1-20 21-40 41-60

Do you have any comments ?

Name   E-mail


Virtual Aircraft Museum


All the World's Rotorcraft


Back AVIATION TOP 100 - www.avitop.com Avitop.com