|
Sikorsky S-58 / H-34 / HSS / Seabat / Seahorse / Choctaw  UH-34D
Designed to overcome the range and offensive payload deficiencies of the anti-submarine HO4S version of the S-55 / H-19, 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 1525hp / 1137kW Wright R-1820 engine, but a completely new semi-monocoque fuselage, larger-diameter four-bladed main and four-bladed tail rotors, and transmission system were introduced, together with main rotor and rear fuselage folding to facilitate shipboard stowage. The tail rotor has servo control and both main and tail rotors have brakes. Fuel capacity is from 750 litres to 1,164 litres depending on model.
With a completely redesigned, downward-sloping tail section, the S-58 also differed from the S-55 in having a three-point, tail-wheel landing gear. Air-oil shock-absorber struts. Mainwheels have rotating struts to reduce drag and weight and toe-operated brakes. 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.
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.
The HSS-2 was designed to meet US Navy requirements for a combined submarine hunter-killer helicopter for operation from carriers and shore basws. During flight testing, it proved its ability to hover over one point for more than three hours continuously, and to complete patrols of up to four hours with large fuel reserves. It entered service in September 1961. On February 1962 it became the first helicopter to set up an over-200 mph. The HSS-2 held all all four of the other major international helicopter speed records for distances up to 620 miles.
 HSS-2
Designated XHSS-1, it flew for the first time on 8 March 1954.
After evaluation of the XHSS-1 an initial ten were ordered. 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 includes the 'winterised' LH-34D (formerly HSS-1L). These models in U.S. Navy service were replacement by the SH-3 Sea King and many were converted to utility transports with UH prefixes.
Subsequent production orders totalled 427 (53-4475 to 4554, 54-882 to 937, -2860 to 2914, -2995 to 3050, 55-5241 to 5261, 56-4284 to 4342, 57-1684 to 1770, and 58-1721) included 21 transfers from the USN. Redesignated as CH-34A in 1962. In addition to redesignated ships, 21 H-34As were rebuilt as CH-34C.
The HSS-2 was designed to meet US Navy requirements for a combined submarine hunter-killer helicopter for operation from carriers and shore bases. During flight testing, it proved its ability to hover over one point for more than three hours continuously, and to complete patrols of up to four hours with large fuel reserves. It entered service in September 1961. On February 1962 it became the first helicopter to set up an over-200 mph. The HSS-2 held all all four of the other major international helicopter speed records for distances up to 620 miles.
One JH-34A was built; 53-4475. 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.
In 1959 a US Marine Corps HUS-1 served as a launching platform for the Martin Bullpup air-to-surface missle during a series of tactical assault trials at Chesapeake Bay.
 The Bullpup was claimed to be the largest radio-controlled missile ever fired from a helicopter.
A troop transport variant was simultaneously acquired by the Marine Corps as the HUS Seahorse. 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, 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 US Marine Corps ordered the HUS-1 Seahorse (UH-34D) version on 15 October 1954; able to carry 12 Marines or a 1350kg load, this variant entered service in February 1957. The Marines received 570 of the S-58 in the utility version (HUS-1 / UH-34D and -1A, 143961 to 143983, 144630 to 144654, 145713 to 145812, 147147 to 147201, 148053 to 148122, 148753 to 148822, 149318 to 149402, 150195 to 150264, 150552 to 150580, 150691, and 150717 to /150729) and 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 / UH-34E) are basically alike, the latter being an amphibious version (eight built, 144655 to 144662 and 32 converted from HUS-1) with pontoons for landing on water. Inflatable flotation gear identified the US Marines' HUS-1A and the US Coast Guard's HUS-1G (Redesignated as HH-34F in 1962). Four HUS-1L (LH-34D) helicopters were modified for operation in the Arctic. Production continued as redesignated UH-34D after 18 September 1962.
The six 1958 HUS-1G were converted HSS-1 for the USCG. The six, 1332 to 1336, and 1343, were redesignated as HH-34F in 1962.
Four HUS-1, including 144658, 145719, and 150220, were modified for Antarctic duty. They were redesignated as LH-34D in 1962.
Eight HUS-1, 147161, 147179, 147191, 147201, 148803, 148804, 148805 and 150691, were converted as HUS-1Z Presidential aircraft. They were redesignated as VH-34D in 1962.
A total of 603 S-58s were delivered to the US Marines.
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 Army accepted the first of 437 new-construction H-34As in April 1955, the first unit being equipped in September 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).
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.
The US Army H-34A, H-34B and H-34C Choctaw helicopters were powered by 1063kW R-1820-84 engines and each carrying 16 troops or eight stretchers in the medevac role. US Army CH-34s maintained a constant patrol along the border of West Germany with Czechoslovakia and East Germany. Army S-58's have the name Choctaw, the CH-34A and CH-34C differing only in the equipment carried.
H-34B were 1960 H-34A conversion, redesignated as CH-34B in 1962.
The H-34C, with SAR modifications, included 56-4305, -4331, -4333, 57-1692, -1698, -1709, and others. They were redesignated as CH-34C in 1962 along with 21 rebuilt and re-serialed H-34As (63-13190 to 13210. 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 including relocation of Battery, Invertors, and Aux Hyd Reservoir. 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. The VH-34D is a VIP transport.
Twenty-three UH-34D went to USAF for export to friendly nations (63-8248/8259, -13006/13014, and -13139/13140) and 44 to USN (152686, 153116/153133, 153556/153558, 153695/153704, 154045, 154889/154902, and 156592/156598), of which 10 went to USAFR as HH-34D with new s/ns (60-6913, -6923, 61-4488/4491, -4529, 63-7972/7974). In 1964 U.S. Marines flying the HUS-1 version of the S-58 saved 1,500 Vietnamese villagers from floodwaters. The aircraft also was used to recover the space capsule of Alan B. Shepard, Jr., America's first astronaut in space.
The CH-34 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. US Army CH-34s maintained a constant patrol along the border of West Germany with Czechoslovakia and East Germany. 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 missions 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. One SH-34G was exported to Germany; 152188.
SH-34J production in 1962 was for the USN (151729 to 151731, 152380 to 152381, and 153617 to 153622) of which several transferred to the USAF as HH-34J.
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. When production was terminated in January 1970, Sikorsky had manufactured a total 1,820 S-58s of all versions.
The S-58T was first flown on 26 August 1970 with P&WC PT6T-3 twinpack turboshaft engine. Kits were built by Sikorsky but 160 conversions were carried out by California Helicopter International.
Offering a 5,000-pound sling load, the Sikorsky S-58T has a 110 knots normal cruise, a 10-knot edge on both the 212 and the 205A. Furthermore, while all three aircraft can hoist a 5,000-pound sling load, the -58T can do it at higher altitudes. The S-58T manages a gross lift at 6,500 feet. After acquiring a licence in 1956 to manufacture the Sikorsky S-58 helicopter, Westland imported one of these aircraft in HSS-1 configuration. Given the British serial number XL722, this aircraft was test-flown for a time with its original 1525hp Wright R-1820-84 engine before being modified to accept a 1100shp Napier Gazelle NGa.11 gas turbine.
 Napier Gazelle powered Wessex first flight 17 May 1957 at Yeovil
In its new form it was flown for the first time on 17 May 1957, and was later joined by two pre-production Wessex HAS Mk.1's for Naval trials; the first of these flew on 20 June 1958.
Wessex features - Main and tail rotor each have four blades. Blades attached to hub by taper bolts. Main rotor blades fold manually. Rotor brake fitted. Shaft drive to main rotor through double epicyclic gear. Shaft drive to tail rotor through intermediate and tail gearboxes. Tail end folds to port and forward for stowage. Tail rotor carried at tip of vertical stabilising fin. Small horizontal stabiliser inset in leading-edge of fin.
All blades of light-alloy extruded spar and light-alloy bonded trailing-edge structure. The fuselage is a light-alloy semi-monocoque structure, with steel tube support structure for main rotor gearbox.
Landing gear is a non-retractable tailwheel type. All three units fitted with Westland oleo-pneumatic shock-absorber. Dunlop wheels, tyres and hydraulic disc brakes. Tubeless treaded mainwheel tyres, size 6.00 x 11. Tailwheel tyre size 6.00 x 6.
Compressor bleed air for heating. Ambient air circulation by fan. High-pressure hydraulic system for powered flying controls and 272kg capacity hoist. 24V DC electrical system, with two 6kW generators.
The HAS Mk.1, powered by a Napier Gazelle of 1,450shp (1081kW), went into production in 1959 for the Royal Navy as a submarine search and strike helicopter equipped with dipping Asdic and provision for one or two homing torpedoes. Powered by a 1450shp Gazelle Mk.161 engine, it began service trials with No.700H Flight in April 1960 and has since been delivered to Nos. 706, 737, 771, 815, 819 and 848 Squadrons. The first of these to commission, in July 1961, was No.815; the Wessexes of No.848 Squadron were for commando assault duties aboard H.M.S. Albion, having the ASW gear removed to make room for 16 troops or 8 stretchers and a medical attendant in the main cabin. Alternatively, a slung load of 1814kg can be suspended from an under-fuselage hook.
The original version was the Wessex HAS.Mk1, powered by a Napier Gazelle of 1,450shp (1081kW). The HAS.1 was undergoing service trials with No.700H Sqn during 1960, during which it first landed on an aircraft carrier.
The HAS.1 was supplanted by the Wessex HAS.Mk3 version popularly called the Camel because of its humpbacked search radar above the rear fuselage.
 HAS.1
The most extraordinary feature of the Wessex HAS.3 is the stack of avionics and anti-submarine gear that the Royal Navy has fitted it with; the latter consisting of radar and sonar equipment linked together by a small computer to give a “total picture”. All this is operated by a third crewman seated at the rear of the aircraft, in an area which looks like a second cockpit. The sophisticated radar is used for navigation as well as sub hunting.
In August 1964 it was announced that the Iraqi Air Force was acquiring 12 Wessex HC.2. The cost was to be $8m including spares. The Ghanaian air force ordered two Wessex Mk.53.
Much more important numerically is the Wessex HU.Mk 5 version, the Royal Marine Commando assault version. These twin-engine machines once numbered almost 100. The Navy's HU Mk.5, for which two orders were placed, entered service in summer 1964 as a commando-carrier assault transport.
In the early 1960s the RAF required a powerful general-purpose helicopter capable of troop-carrying, air ambulance and ground attack roles. And doors on each side of flight deck and on starboard side of cabin. Two flexible fuel tanks under cabin floor, total capacity 1,409 litres. Provision for carrying two 500 litre auxiliary tanks in cabin for ferry purposes. Refuelling point in starboard side of fuselage. Oil capacity 9 litres per engine, 19 litres in main gearbox.
Towards the end of 1959 two Whirlwinds joined the Queen’s Flight, designated HCC Mk.8, they had Alvis Leonides Major engines and special interiors.
 HCC Mk.8
 Westland Wessex HC Mk.2
The RAAF ordered 27 Westland Wessex Mk31B carrier-borne anti-submarine/search & rescue helicopter from Westland Aircraft Ltd in July 1961. The first was delivered on 1 Nov 1962 and the last on 4 Nov 1963. The HAS Mk.31's are similar to the HAS Mk.1 apart from their 1540shp Gazelle Mk.162 engines. Australia's navy anti-submarine duties started in August 1962.
Westland built 356 Wessex in all (including those for the civil market): the HAS Mk.1 version for the Royal Navy; the HC Mk.2 tactical transport version for the RAF; the HAS Mk.3 antisubmarine version with 1550shp Gazelle NGa.18 turbine; the HU. Mk.5 for various roles on the Navy's commando carriers; the HAS Mk.31 for the Royal Australian Navy; the Wessex Mk.52 for the Iraqui Navy (12); the Wessex Mk.53 for Ghana (3); the Wessex Mk.54 for Borneo and the Wessex Mk.60 commercial version. Seven Wessex Mk.60's have been built for Bristow Helicopters Ltd. These are 10-passenger commercial equivalents of the Mk.2 and operate in support of the oil and gas drilling rigs in the North Sea.
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.
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 HAS. Mk 1
Initial production version, developed for the Royal Navy, with one 1,450shp Napier Gazelle 161 turboshaft engine. Re-engined with a 1,100shp Gazelle NGa.11, flew for the first time 17 May 1957.
Westland Wessex HC. Mk 2
High-performance development of the Mk 1 with two coupled 1,350shp Bristol Siddeley Gnome Mk 110/111 turboshaft engines. Power limitation of 1,550shp at rotor head. Prototype converted from Wessex 1, flew for the first time 18 January 1962, and the first production model (XR588) 5 October 1962.
Westland Wessex Mk 3
Similar to Mk 1, but with 1,850shp Gazelle NGa.18 165 turboshaft engine.
Westland Wessex HCC. Mk 4
Queen's Royal Flight helicopter.
Westland Wessex HC. Mk 5
SAR helicopter of the Royal Air Force based in Cyprus.
Westland Wessex HU. Mk 5
Similar to Mk 2, for Commando assault duties from carriers of the Royal Navy. Design work began in April 1962 and construction of the prototype was started in May 1962. In service with A&EE (1) and 84 Squadron Akrotiri Cyprus (5).
Westland Wessex HAS. Mk 31
Generally similar to Mk 1, but with a 1,540shp Gazelle Mk 162 engine. Ordered for the Royal Australian Navy for anti-submarine duties from HMAS Melbourne.
Westland Wessex Mk 52
Similar to Mk 2, for Iraqi Air Force.
Westland Wessex Mk 53
Similar to Mk 2, for Ghana Air Force.
Westland Wessex Mk 60
Civil version in service with Uruguayan Navy.
Specifications:
Sikorsky S-58 / H-34 Choctaw
Engine: 1 x Wright R-1820, 1137kW / 1504 hp
Main rotor diameter: 56 ft / 17.1m
Length: 17.3m
Height: 4.9m
Max take-off weight: 6350kg
Empty weight: 3754kg
Max speed: 178 km/h / 150 kt
Cruising speed: 158km/h
Rate of climb: 5.6m/s
Service ceiling: 2900m
Range: 450km
Crew: 2
Passengers: 12-18
CH-34A/H-34A Choctaw
Transport and general purpose helicopter for US Army.
Engine: 1,525 hp Wright R 1820 84B/D piston.
Rotors: 4-blade main; 4-blade tail.
Operating speed: 40 - 128 knots
Mainwheel tyres 11.00 x 12
Tailwheel tyre 6.00 x 6
Wheel track 3.66m
Wheelbase 8.75m
Cabin length: 13 ft
Seats: 20
CH-34C / H-34C Choctaw
Similar to CH-34A
Operating speed: 40 - 128 knots
Mainwheel tyres 11.00 x 12
Tailwheel tyre 6.00 x 6
Wheel track 3.66m
Wheelbase 8.75m
Cabin length: 13 ft
LH-34D / HSS-1L Anti-submarine version ordered by US Navy 30 June 1952; accepted for service in February 1954.
Engine: 1,425 hp Wright R-1820
Mainwheel tyres 11.00 x 12
Tailwheel tyre 6.00 x 6
Wheel track 3.66m
Wheelbase 8.75m
Cabin length: 13 ft
UH-34D / HUS-1 Seahorse
Utility version for Marines; ordered 15 October 1954 and accepted for service January 1957.
Engine: Wright R-1820-84
Main rotor: 56'0"
Length: 46'8"
Max speed: 123 mph
Mainwheel tyres 11.00 x 12
Tailwheel tyre 6.00 x 6
Wheel track 3.66m
Wheelbase 8.75m
Cabin length: 13 ft
UH-34E / HUS-1A Seahorse
HSS-2
Engines: 2 x 1250 shp General Electric T-58-GE-8.
Main rotor diameter: 62 ft
Main rotor disc area: 3019 sq.ft
Length: 54 ft 9 in
Width over floats: 15 ft 8 in
Empty weight: 11,194 lb
Normal takeoff weight: 17,768 lb
Fuel capacity: 575 gal
Max speed: 148 mph at SL
Hover ceiling OGE: 6000 ft
Range: 535 mi
Weapon load: 840 lb
S-58B
Westland Wessex HAS.I
Engine: 1 x Napier Gazelle Mk.161, 1450 shp
Main rotor diameter: 56 ft
Length: 49 ft 11 in
Height: 15 ft 10 in
Main rotor disc area: 2460 sq.ft
Empty weight: 7600 lb
MTOW: 12,600 lb
Fuel capacity: 266 gal
Aux fuel capacity: 200 gal
Max speed: 132 mph at SL
Cruise sped: 115 mph
Sevice ceiling: 14,200 ft
Max range w/aux fuel: 600 mi Westland WessexHC Mk.2
Engine: 2 x Bristol Siddeley Gnome Mk.110 or Mk.111 turboshaft, 1007kW / 1350 shp total
Type 10 coupling gearbox
Rotor head rating: 1,550shp
Main rotor diameter: 17.07m
Length rotors turning: 20.04m
Height: 4.93m
Max take-off weight: 6123kg
Empty weight: 3767kg
Max speed: 212km/h
Range with max fuel: 769km
Crew: 1 -3
Capacity: 16 seats
Westland Wessex HC Mk.5
Engines: One Bristol Siddeley Gnome Mk 112 and one Gnome Mk 113
Type 11 coupling gearbox
Main rotor diameter: 17.07m
Length rotors turning: 20.04m
Height: 4.93m
Crew: 1 -3
Capacity: 16 seats / 1814 kg
Westland Wessex HU.Mk 6
|
