|Sikorsky S-65 / CH-53 Sea Stallion|
Currently the largest and heaviest helicopter in the western world, the S-65A is something of a hybrid, its fuselage being, in essence, a scaled-up version of that used on the S-61R, while its rotor and transmission system and certain other dynamic components are inherited from the S-64 Skycrane. It does not have the boat-type hull of the S-61R, but the flat-bottomed body is watertight and has similar sponsons amidships in which are housed fuel tanks and the main undercarriage members when retracted. The nosewheel is also fully retractable. Basic empty weight is reduced by the use of titanium in the rotor head. The S-65A carries a crew of 3 and can airlift 38 troops and their equipment, 24 casualty litters and 4 medical attendants, or some 3630kg of cargo within the fuselage. A let-down rear ramp provides access for such military loads as 2 jeeps, a Hawk missiles, or a 105mm howitzer and its carriage. A slung load of some 5900kg can be lifted on an under-fuselage hook.
In August 1962 it was announced that the S-65A had been selected as a new ship-borne heavy assault transport for the U.S. Marine Corps, with the military title CH-53A Sea Stallion. A prototype flew on 14 October 1964, and delivery of the first of one hundred and six production CH-53A's began in September 1966. Since January 1967 the Sea Stallion has been serving with Marine Squadron HMH-463 in Vietnam, and by that summer some thirty Sea Stallions had been delivered. Standard powerplant is the T64-GE-6 shaft turbine, though the 3080shp T64-GE-1 or 3435shp T64-GE-16 may be fitted. One CH-53A with standard engines has been flown at a gross weight of 20865kg, of which 9072kg was payload.
A second military variant is the HH-53B, flown for the first time on 15 March 1967. This version has 3080shp T64-GE-3 engines and certain features, such as a rescue hoist, jettisonable auxiliary fuel tanks and a telescopic in-flight refuelling probe, not found on the CH-53A. It also has defensive machine gun positions fore and aft. The HH-53B is employed by the Aerospace Rescue and Recovery Service of the U.S. Air Force, and delivery of an initial batch of eight, ordered in September 1966, began in June 1967. Two of these aircraft are stationed at Cape Kennedy in connection with the Apollo manned spacecraft programme.
Parallel with the military variants, Sikorsky have had under development a commercial model of the S-65A. This is currently envisaged with 3435shp T64 engines and an enlarged pressurised fuselage to seat 67 passengers.
K.Munson "Helicopters And Other Rotorcraft Since 1907", 1968
Using much of the experience gained with the S-61 and the dynamic components (rotor, transmission and anti-torque rotor) of the S-64 flying crane, Sikorsky designed a new family of helicopters designated S-65, various versions of which have been developed. On the basis of the S-61R project for the Marines, the American company proposed the S-65A with a completely redesigned, large-capacity fuselage, capable of transporting 37 equipped troops or 24 stretchers with 4 medical attendants. The US Navy, which is responsible for acquisitions for the Marines, announced the choice of the S-65A in August 1962.
The CH-53 Sea Stallion had the six-blade rotor and tail rotor of the S-64 flying crane, driven through the same transmission by new General Electric T64 engines. The fuselage no longer had the boat-type hull of the S-61, although it could land on water with two stub wings acting as stabilizers and containing the fuel tanks and, at the back, the bay for the fully retractable main landing gear units. The cargo hold, equipped with a loading ramp and an automatic loading and unloading system (which can be operated even when the helicopter is in flight), can take two jeeps, antiaircraft missiles with their fire control systems or a 105mm howitzer.
The first Sea Stallion flew on 14 October 1965, and delivery of the first 106 helicopters began in September 1966. The aircraft were assigned to Marine Squadron HMH-463 in Vietnam in January 1967. At that period, it was the largest helicopter in the Western world. On 17 February 1968, a CH-53A with modified T64 engines took off with a gross weight of 23540kg and a 9925kg payload, establishing an unofficial record. On 23 October of the following year a Sea Stallion demonstrated surprising manoeuvrability when it performed a series of loops and rolls with Lt.-Col. Robert Guay of the Marines and Sikorsky test pilot Byron Graham at the controls, carrying a gross weight of 12250kg. During these manoeuvres, the helicopter supported from -0.2 to 2.8g.
The Sea Stallion also aroused some interest in other countries where there was a requirement for a helicopter for troop transport. Thus the S-65A was also ordered by Germany, where it was built under license by VFW-Fokker as the CH-53G. Another eight aircraft, modified for use in hot/high conditions, were exported to Israel.
In September 1966, the USAF also ordered this big helicopter for its rescue service to assist space programmes and recover pilots from war zones. The eight HH-53B ordered for the USAF were known as "Super Jolly Green Giants" and fitted with in-flight refuelling probes, jettisonable auxiliary fuel tanks, rescue hoists and all-weather avionics. Fifty-eight of the subsequent HH-53C variant with uprated turbines (3435shp each) were built. After having used the early production aircraft, the US Marine Corps also asked for more powerful engines to be installed, and the result was the CH-53D with 3925shp T64-GE-423 engines. In this version, the tail and rotor could be folded back automatically, and a high density cabin layout was available to accommodate 64 troops, equivalent to the S-65C export version. A total of 265 CH-53As and Ds were built for the Marines; the last left the factory on 31 January 1972.
To complete its experiments with the RH-3A, the US Navy borrowed nine CH-53Ds from the Marines, fitted with devices for the detection, sweeping and neutralization of all types of mines. This variant was designated RH-53D, and 30 were produced for the US Navy and six for the Iranian Navy. The RH-53 has 1900 liter supplementary fuel tanks, a 270kg hoist and 11340kg cargo hook. At the beginning of 1973, these helicopters were used by US Navy Task Force 78 for Operation Endsweep, to free the North Vietnamese ports of mines.
The latest version of the S-65 to be built is the CH-53E Super Stallion for the US Navy. This is a much modified version with three 4380shp General Electric T64-GE-416 engines and strengthened transmission to withstand the increase in power. The fuselage is about 2m longer than that of the CH-53D and the tail pylon is canted to port. The main rotor has also been improved and has seven composite blades (its predecessor had six light alloy ones). Thirty-three CH-53Es were initially ordered by the Marines and 16 by the US Navy. The type is still in production.
G.Apostolo "The Illustrated Encyclopedia of Helicopters", 1984
For US Marine Corps use Sikorsky developed the Sikorsky S-65 heavy assault transport helicopter as the CH-53 Sea Stallion, first flown on 14 October 1964. It incorporated some components used in the S-64 Skycrane but had a watertight hull and was powered by two 2125kW General Electric T64-GE6 engines. It had rear-loading doors, and among the specified loads were a 105mm howitzer or 38 combat-equipped troops. The initial production version was the CH-53A, delivered from September 1966, but the CH-53D introduced in March 1969 had 2927kW T64-GE-413 engines. A specialised minesweeping version, the RH-53D, was first flown on 27 October 1972. HH-53B and HH-53C SAR variants were built for the US Air Force, the former equipped to a standard similar to that of the HH-3E and powered by 2297kW T64-GE-3 engines; it was first flown on 15 March 1967. More powerful 3,925kW T64-GE-7 engines powered the improved HH-53C, the same powerplant being installed in the CH-53G produced for the German army. Two S-65Oe rescue helicopters were delivered to the Austrian air force in 1970.
Work began in 1971 on an enlarged version with a lengthened fuselage, a new rotor system and three 3266kW T64-GE-416 engines. The US Navy contract covering two prototypes and subsequent flight test was awarded in 1973, and the YCH-53E flew for the first time on 1 March 1974; the first CH-53E Super Stallion delivery to the US Marine Corps took place on 16 June 1981. Since 1982 Sikorsky has been developing the MH-53E mine countermeasures variant. It incorporates major equipment changes and has much enlarged sponsons to carry an additional 3785 litres of fuel.
YCH-53A: winner of the HH(X) competition, two prototype CH-53As were completed for US Navy evaluation, by March 1966; first flight made by second aircraft (BuNo. 151614) on 14 October 1964, powered by two T64-GE-6 turboshafts
CH-53A: initial production version for US Marine Corps, deliveries commencing in September 1965; accelerated deployment to South East Asia made after improvements to engine intake filters, defensive armament, crew armour and external lifting capability; selected T64-GE-1 engines retrofitted for extended running at maximum power output when necessary; fitted with hardpoints for towing mine-sweeping gear from 34th aircraft onwards; used by USAF for crew training and later for covert operations in Vietnam and Laos (seven aircraft borrowed from and returned to Navy); 139 built
RH-53A: 15 dedicated mine-counter-measures versions delivered to the Navy via the Marine Corps; re-engined with T64-GE-413 turboshafts; rectangular frame mounted on rear ramp to tow mine clearing sled and rear view mirrors fitted on either side of the nose; used to clear North Vietnamese mines during Operation Endsweep in 1973; RH-53As replaced by RH-53Ds in Navy service and aircraft returned to Marines
TH-53A: former USMC CH~53As used by USAF from 1989 onwards to train MH-53 crews at Kirtland AFB, NM; at least three aircraft in use, stripped of most equipment and camouflaged
HH-53B: eight aircraft similar to CH-53A but delivered to USAF Aerospace Rescue and Recovery Service to supplement HH-3s in South East Asia; refuelling probe relocated to starboard side of nose, pylons fitted to allow carriage of external fuel tanks; armed with three pintle-mounted GAU-2A/B 7.62mm Miniguns and powered by T64-GE-3s, later replaced by T64-GE-7s; quickly supplemented by HH-53Cs and re-assigned to CONUS, the last four HH-53Bs were modified to MH-53J standard in the late 1980s
CH-53C: 22 aircraft built for heavy-lift duties with the USAF; fitted with sponsons and external tanks as developed for HH-53C, it was similar in most respects to this version but lacked a refuelling probe; replaced CH-53As on loan from USMC for covert operations in Laos; later operated by TAC and USAFE; seven surviving CH-53Cs brought up to MH-53J standard in late 1980s
HH-53C: refined version of HH-53B, 44 of which were built for USAF ARRS for combat rescue; dubbed 'Super Jolly Green Giant'; dispensed with bracing struts fore the external pylons, and included additional crew armour, and better radio fit to facilitate operations with HC-130 tankers; RHAW and IR jamming systems introduced as a result of experience in North Vietnam during 1972; HH-53Cs used in support of Apollo space missions for emergency capsule rescue; HH-53Cs remained in USAF service until late 1980s when all were converted to MH-53J standard
S-65C-2 (S-65O): export version of CH-53C, two of which were delivered to the Austrian air force in 1970; later retired from use due to operating costs and passed on to Israel in 1981
S-65-C3: only other export version of H-53, delivered to Israel from 1969; corresponding to HH-53C, 33 aircraft supplemented by two additional S-65s from Austria in 1981; surviving aircraft now being upgraded by IAI subsidiary MATA Helicopters
CH-53D: improved version of CH-53A fitted with new transmission increasing hot-and-high performance, first flown on 27 January 1969; 124 built
RH-53D: first flown 27 October 1972; 30 aircraft (named Sea Stallion) specifically developed for anti-mine warfare in the light of positive experience with RH-53A; fitted with an initial powerplant of two T64-GE-415s, RH-53D also differs from RH-53A by inclusion of refuelling probe, automatic flight control system, more powerful cargo hook, and rescue winch; armed with two'swivel-mounted 12.7mm machine-guns; six delivered to Imperial Iranian navy before the fall of the Shah
VH-53D: two CH-53Ds delivered to USMC for VIP transport
CH-53G: aircraft built under licence by VFW for a German army order for 135 examples, later reduced to 110; 20 assembled by VFW-Fokker entirely from US-supplied components, then progressively increasing indigenous sources; total includes two US-built CH-53Gs; first German-assembled aircraft delivered on 11 October 1971, entered service in-1973
YHH-53H: first aircraft to be fitted with 'Pave Low Ií, in trials for a projected night/ all-weather combat rescue/infiltration mission; fitted with early low-light TV system which proved inadequate, though the first successful night rescue was made with an improved system in December 1972, in Laos; aircraft later modified to 'Pave Low II' standard, with external sponsons and tanks
HH-53H: eight HH-53Cs and YHH-53H modified to definitive 'Pave Low III' standard; delivered between 1979 and 1980 and fitted with FLIR, TF radar, INS, computer generated moving map display, RHAW and chaff/flare dispensers; later re-designated MH-53H
MH-53H: redesignation and modification of HH-53H under the Constant Green programme; all 'Pave Low III' aircraft now being modified to MH-53J standard
MH-53J: modification of 31 HH-53Bs, CH-53Cs and HH-53Cs and modernisation of MH-53Hs to produce 'Pave Low III Enhanced'; fitted with digital databus, improved transmission, T64-GE-415 engines and 453kg of titanium armour; MTOW increased from 19050 to 22680kg; those modified from HH-53Bs retain braced external tank pylons of first Super Jollys
D.Donald "The Complete Encyclopedia of World Aircraft", 1997
On 27 August 1962, it was announced that Sikorsky had been selected by the US Navy to produce a heavy assault transport helicopter for use by the Marine Corps. First flight was made 14 October 1964, and deliveries began in mid-1966.
CH-53A: Initial version utilising many components based on those of the S-64A Skycrane, but powered by two General Electric T64 turboshaft engines and has a watertight hull. A full-size rear opening, with built-in ramp, permits easy loading and unloading, with the aid of a special hydraulically operated internal cargo loading system and floor rollers.
Typical cargo loads include two Jeeps, or two Hawk missiles with cable reels and control console, or a 105 mm howitzer and carriage. An external cargo system permits in-flight pick-up and release without ground assistance.
The CH-53A is able to operate under all-weather and climatic conditions. Its main rotor blades and tail pylon fold hydraulically for stowage on board ship.
CH-53D: Improved CH-53A for US Marine Corps, the first of which was delivered on 3 March 1969. Two T64-GE-413 engines, each with a maximum rating of 2,927kW. A total of 55 troops can be carried in a high-density arrangement. An integral cargo handling system makes it possible for one man to load or unload 1 ton of palletised cargo a minute. Main rotor and tail pylon fold automatically for carrier stowage.
Last CH-53D (the 26th built) was delivered on 31 January 1972. All but the first 34 CH-53s were provided with hardpoints for supporting towing equipment and transferring tow loads to the airframe, so that the US Marine Corps could utilise the aircraft as airborne minesweepers, giving an assault commander the capability of clearing enemy mines from harbours and off beaches without having to wait for surface minesweepers. Tow kits installed in the 15 CH-53Ds operated by the US Navy Squadron HM-12 included automatic flight control system interconnections to provide automatic cable yaw angle retention and aircraft attitude and heading hold; rearview mirrors for pilot and co-pilot; tow cable tension and yaw angle indicator; automatic emergency cable release; towboom and hook system with 6,803kg load capacity when cable was locked to internal towboom; dam to prevent cabin flooding in emergency water landing with lower ramp open; dual hydraulically powered cable winches; racks and cradles for stowage of minesweeping equipment; auxiliary fuel tanks in cabin to increase endurance.
CH-53G: Version of the CH-53 for the German armed forces, with T64-GE-7 engines. A total of 112 were produced, the first of two built by Sikorsky being delivered 31 March 1969. The next 20 were assembled in Germany from US-built components. The remainder embody some 50% components of German manufacture. Prime contractor in Germany was VFW-Fokker, whose first CH-53G flew 11 October 1971. Deliveries completed in 1975.
HH-53B: Eight ordered by USAF in September 1966 for Aerospace Rescue and Recovery Service. The first of these flew 15 March 1967, powered by 2,297kW T64-GE-3 turboshaft engines. Withdrawn from service.
HH-53C: Improved version of the HH-53B, with 2,927kW T64-GE-7 engines, auxiliary jettisonable fuel tanks each of 1,703 litres capacity on new cantilever mounts, flight refuelling probe, and rescue hoist with 76m of cable. External cargo hook of 9,070kg capacity. First HH-53C was delivered to the USAF 30 August 1968. A total of 72 HH-53B/Cs was built. Withdrawn from service.
HH-53H Pave Low III: Special operations version for combat rescue and recovery. Eight converted to MH-53J Pave Low III.
MH-53J Pave Low III Enhanced: US Air Force upgrade of Special Operations Forces combat rescue and recovery fleet; 31 HH-53Bs, HH-53Cs and CH-53Cs converted at NAS Pensacola, Florida, beginning 1986, to MH-53J Pave Low III Enhanced; similar to 11 HH-53H Pave Low III produced earlier, eight survivors of which also converted to MH-53Js; programme completed in 1990. Modifications include Texas Instruments AN/AAQ-10 nose-mounted FLIR, inertial navigation, Doppler radar, computer-projected map display, Navstar GPS, Texas Instruments AN/APQ-158 terrain-following/avoidance radar in offset nose radome, chaff/flare dispensers, Loral AN/ALQ-157 IR jammer on each outrigger pylon, 454kg of extra titanium armour plating and Collins AN/AIC-3 intercom; armament includes three 7.62mm or 12.7mm machine guns firing through windows on each side and from open rear ramp. Power plant is two 3,266kW General Electric T64-GE-415 turboshafts; maximum T-O weight increased to 22,680kg. Further upgrades planned to improve combat effectiveness and service life.
MH-53M Pave Low IV: Internal upgrade featuring new avionics and defence aids, including an integrated AP-102A weapon systems computer to speed up target acquisition. All 39 existing MH-53J Pave Low III's are expected to be converted.
RH-53D: Specially equipped mine sweeping version for the US Navy and Iran.
TH-53A: Training version in service with the USAF.
YCH-53E: Three-engined development of the CH-53D.
VH-53D: Presidential helicopter of US Marine Corps.
S-65-Oe: Two ordered in 1969 by Austrian Air Force and delivered in 1970. Used for rescue duties in the Alps, they have the same rescue hoist as the HH-53B/C, fittings for auxiliary fuel tanks and accommodation for 38 passengers. Withdrawn from service.
S-65C: Commercial intercity helicopter proposal based on military CH-53.
Yasur 2000: Upgrade of 30 Israeli Air Force CH-53Ds by IAI. Improved avionics and structural changes to extend service life. Other modifications include internal auxiliary fuel tanks, flight refuelling boom, rescue hoist, crashworthy seats and cockpit armour.
DESIGN FEATURES: Rotor system and transmission generally similar to those of S-64A Skycrane, but main rotor head is of titanium and steel, and has folding blades.
STRUCTURE: Fuselage is a conventional semi-monocoque structure of aluminium, steel and titanium. Folding tail pylon. Large horizontal stabiliser on starboard side of tail rotor pylon.
LANDING GEAR: Retractable tricycle type, with twin wheels on each unit. Main units retract into rear of sponsons on each side of fuselage. Fully castoring nose unit. Mainwheels and nosewheels have tyres size 25.65 x 8.50-10, pressure 6.55 bars.
POWER PLANT: Normally two 2,125kW General Electric T64-GE-6 turboshaft engines, mounted in pod on each side of main rotor pylon. The CH-53A can also utilise, without airframe modification, the T64-GE-1 engine of 2,297kW or the later T64-GE-16 (mod) engine of 2,561.5kW. Two self-sealing bladder fuel tanks, each with capacity of 1,192 litres, housed in forward part of sponsons. Total fuel capacity 2,384 litres.
ACCOMMODATION: Crew of three. Main cabin accommodates 37 combat-equipped troops on inward-facing seats. Provision for carrying 24 stretchers and four attendants. Roller-skid track combination in floor for handling heavy freight. Door on starboard side of cabin at front. Rear-loading ramp.
Jane's Helicopter Markets and Systems
Technical data for Sikorsky CH-53D
Engine: 2 x General Electric T64-GE-412 turboshaft, rated at 2926kW, main rotor diameter: 22.02m, fuselage length: 20.5m, height: 7.6m, take-off weight: 19050kg, empty weight: 10650kg, max speed: 315km/h, cruising speed: 278km/h, range with payload: 2075km, rate of climb: 11m/s, service ceiling: 6220km, internal (external) payload: 3710kg (9070kg)