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Sikorsky Giant Helicopters: S-64, S-65, & S-80

v1.0.0 / 01 jun 04 / greg goebel / public domain

* The development of turboshaft engines in the 1950s provided truly adequate powerplants for heavy-lift helicopters. Using such improved technologies, the Sikorsky company developed a series of large turbine-powered helicopters, beginning with the twin-engine "S-64 Skycrane", which led to the twin-engine "S-65 Sea Stallion" and then its three-engine derivative, the "S-80 Super Stallion". This document provides a history and description of the Sikorsky giant helicopters.


[1] S-60 / S-64 SKYCRANE / US ARMY CH-54A & CH-54B TARHE
[2] S-65 ORIGINS / US MARINE CH-53A & CH-53D SEA STALLION
[3] US NAVY RH-54A & RH-54D SEA STALLION
[4] USAF HH-53B, HH-53C, & CH-53C
[5] USAF PAVE LOW: HH-53H / MH-53H, MH-53J, TH-53J, MH-53M
[6] S-65 IN FOREIGN SERVICE
[7] S-80 ORIGINS / US MARINE & NAVY SERVICE / JAPANESE SERVICE
[8] S-80 UPGRADES
[9] VARIANT SUMMARY
[10] COMMENTS, SOURCES, & REVISION HISTORY

[1] S-60 / S-64 SKYCRANE / US ARMY CH-54A & CH-54B TARHE

* In May 1958, Sikorsky began work on an experimental "flying crane" helicopter, the "S-60", derived from the S-56 (HR2S-1 / H-37 Mohave) heavy-lift helicopter. The S-60 inherited the S-56's rotor system and twin "power modules", each with a Pratt & Whitney (P&W) R-2800 Double Wasp radial piston engine, but had a stripped-down fuselage with long "taildragger" landing gear that allowed it to straddle cargoes. The crew operated from a glass-in nose module; the copilot could swing his seat around to face the back to keep an eye on sling loads, controlling the helicopter in this position with an alternate set of controls. The S-60 had an automatic stabilization system to allow it to hover precisely, using inputs from a sidestick controller system.

The S-60 performed its first flight on 25 March 1959. It was intended only as a proof-of-concept demonstrator, since the company believed that a production machine would need to be powered by turboshaft engines to provide greater lift capability. Igor Sikorsky envisioned his flying crane carrying specialized modules or "pods", such as a field hospital or a radar station, as well as general heavy cargoes.

To investigate the S-60's ability to carry slung loads, Sikorsky had a test platform built, which he and two of his senior engineers took a ride on early in the flight test program. The two engineers found the ride somewhat nerve-wracking, but Sikorsky -- then about 70 years old -- simply strolled around the platform, checking the cable tension, as calmly as if he had been walking around on the ground. This was almost certainly not showing off; Sikorsky was a cultivated person with an old-world sense of dignity. However, he had also been a pioneer of flight in the days when flying was entirely dangerous, and no doubt it felt good to revisit some of the thrills of the good old days.

In any case, the company demonstrated the S-60 to the US Army and US Navy during 1960. The military had already worked on the development of flying crane helicopters in the early 1950s, though they were unable to bring a machine to production. The Navy was interested in demonstrations of S-60 towing a minesweeping sled, and particularly interested in demonstrations where it hauled cargoes between ship and shore.

* With the Navy intrigued by the idea, Sikorsky began to move ahead on the production machine. The first obstacle was that a suitable turboshaft powerplant wasn't available. There were two engines under development that seemed like they could be adapted to the task, including the General Electric (GE) T64 turboshaft and the P&W JT12 turbojet. The problem with the GE T64 was that it had a front power shaft, and Sikorsky required a rear power shaft. GE didn't feel there was enough of a market to justify developing another major variant of the T64. The problem with the JT12 was that it would require substantial work to turn it into a turboshaft. However, both Sikorsky and P&W were members of the United Aircraft (UA) industrial group, and senior UA managers immediately committed to turning the JT12 into a turboshaft.

The S-60 was lost in a crash in April 1961, but by that time the prototype for the turboshaft-powered "S-64 Skycrane" was already being built. The US military hadn't provided as much support as hoped for, but the West German government had decided to evaluate the S-64 and bought two of the first three machines built, the third being retained by Sikorsky for development testing.

The initial prototype had a general configuration along the lines of that of the S-60, but was a generally new machine. The cockpit had accommodations for pilot, copilot, and a rearward-facing crane operator / assistant pilot, plus folding seats for two passengers. It was powered by twin P&W JFTD-12A turboshafts with 3,020 kW (4,050 SHP) each, and had a six-bladed main rotor system and a four-bladed tail rotor. The tricycle landing gear had single wheels on each assembly. There was a retractable tail bumper.

The S-64 performed its initial flight on 9 May 1962. The Germans didn't place orders following their evaluation, but the US Army became interested enough in the machine to place an order for six "S-64A" helicopters for evaluation in June 1963, with the service designation "YCH-54A Tarhe". They were similar to the prototypes, but had production P&W T73-P-1 (notice the military designation) turboshafts with 3,360 kW (4,500 SHP) each.

The evaluation went well, and was followed by orders for 54 full-production "CH-54As". This order was followed by one for 37 "CH-54Bs", featuring uprated P&W T73-P-700 engines with 3,580 kW (4,800 SHP) each; dual instead of single main gear wheels; and structural improvements to permit greater lift capacity. The CH-54B had actually been built under US Navy sponsorship as part of a dubious scheme to deliver Polaris strategic missiles to submarines at sea, but it fell well short of its load targets and the Navy never bought any S-64s. The last of the S-64s built for the US Army was delivered in 1972.

   SIKORSKY S-64 / CH-54B TARHE:
   _____________________   _________________   _______________________
 
   spec                    metric              english
   _____________________   _________________   _______________________

   main rotor diameter     21.95 meters        72 feet
   fuselage length         21.41 meters        70 feet 3 inches
   footprint length        26.97 meters        88 feet 6 inches
   height (tail rotor)     7.75 meters         25 feet 5 inches

   empty weight            8,725 kilograms     19,235 pounds
   max loaded weight       19,050 kilograms    42,000 pounds
   maximum speed           205 KPH             125 MPH / 110 KT
   range                   400 kilometers      250 MI / 220 NMI
   _____________________   _________________   _______________________

The Army deployed the type to Vietnam in 1965, initially sending four of the YCH-54A evaluation machines, and found it very useful for delivering heavy equipment, and particularly for retrieving downed aircraft. Some sources claim it was also used to clear helicopter landing sites in jungles by dropping large bombs, though this this mission, known as "Commando Vault", was usually performed by C-130 Hercules transports.

However, the Tarhe was expensive, with a cost at least seven times greater than that of a Bell UH-1 Huey helicopter, and Sikorsky's concept of using modular pods turned out to be more of a logistical nuisance than a benefit in field military operations. Ironically, its modular design concept proved inflexible: the military wanted a helicopter that could be used as a skycrane and a transport, not one that had to be fitted with a special module for transport operations.

Operational losses were low, however, with one shot down and eight lost in mishaps in eight years of combat operations. There were problems with engine ingestion of fine dust and sand on hot and dry days, and so in 1967 Sikorsky developed a basket-like inlet cover, the "Engine Air Particle Separator (EAPS)", that sucked in air in a spiral flow to toss most of the dust and sand out of the inlet. EAPS was fitted to CH-54s in the field.

The Tarhe was retained in Army National Guard service until the early 1990s. It was not only used for military exercises, but also for fire-fighting, carrying a big water bucket on a sling. The Tarhe was finally replaced by the Boeing CH-47C Chinook, somewhat to the regret of the crews, who had found the Sikorsky machine to be capable and highly reliable.

In 1968, Sikorsky introduced a commercial variant, the "S-64E", and sold about ten of them for oil drilling, construction, logging, and forest fire fighting operations. However, the type was too expensive to operate to see much civil service. The Skycrane still remains in limited service for fire-fighting and forestry operations.

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[2] S-65 ORIGINS / US MARINE CH-53A & CH-53D SEA STALLION

* Although Sikorsky's high hopes for the S-64 didn't pan out, the company was able to use the basic technology to build a much more successful helicopter. In 1960, the US Marines began to seek an replacement for their old S-56 piston-powered helicopters, originally working with the other three US armed services on the "Tri-Service VTOL transport", which would eventually emerge as the Vought-Hiller-Ryan XC-142A tiltwing. The word "eventually" is significant, because the design became more elaborate and the program stretched out. The Marines finally decided that they couldn't get a workable machine in a satisfactory timeframe and dropped out. This was just as well, because the XC-142A, although a very innovative and capable machine, would never enter production.

In March 1962, the US Navy Bureau of Weapons, acting on behalf of the Marines, issued a request for a "Heavy Helicopter Experimental / HH(X)". The specifications dictated a load capability of 3,630 kilograms (8,000 pounds) with an operational radius of 185 kilometers (100 NMI) at a speed of 278 KPH (150 KT). The HH(X) was to be used in the assault transport, aircraft recovery, personnel transport, and medical evacuation roles. In the assault transport role, it was to be mostly used to haul heavy equipment.

In response, Boeing Vertol offered a modified version of the Chinook; Kaman offered a development of the British Fairey Rotodyne compound helicopter; and Sikorsky offered what amounted to a scaled-up version of the S-61, with twin GE T64 turboshafts and the dynamic system of the S-64, to be designated the "S-65". Kaman's proposal quickly died when the British government dropped its backing of the Rotodyne program. Competition between Boeing Vertol and Sikorsky was intense, with the Boeing Vertol having something of an edge because the type was being acquired by the US Army, but Sikorsky threw all it had into the contest and was awarded the contract in July 1962.

The Marines originally wanted to buy four prototypes but ran into funding problems. Sikorsky, determined to keep the deal, cut their estimate for development costs and said that the program could be done with two prototypes. The military bought off on the proposal, and in September 1962 Sikorsky was awarded a contract for a little under $10 million USD for two "YCH-53A" prototypes, as well as a mockup and a ground-test airframe.

The development program did not go entirely smoothly, due to a shortage of engineering resources plus various failures of subcontractors and the government, but these problems were gradually overcome. There was also the problem that US Defense Secretary Robert S. McNamara was pushing "commonality" between the armed services and pressuring the Marines to obtain the Chinook anyway, but the Marines managed to convince McNamara's people that the Chinook couldn't meet requirements without a lot of expensive changes.

All these obstacles overcome, the first YCH-53A performed its initial flight at the Sikorsky plant in Stratford, Connecticut, on 14 October 1964, about four months behind schedule. The Marines had already placed an initial production contract for 16 machines in September. Flight trials went more smoothly than expected, helping make up for the lost time in development, and the type entered USMC service in September 1965 as the "CH-53A Sea Stallion". The Marines were in such a hurry to get the CH-54A that they accepted it for service even before trials were completed. A total of 141 CH-53As were built, including the two prototypes.

The CH-53A used a fuselage design along the lines of that of the Sikorsky S-61R / Jolly Green Giant series. The CH-53A had passenger doors on each side of the fuselage behind the cockpit; a power-operated rear loading ramp; sponsons on each side of the rear fuselage; and tricycle landing retractable landing gear, with twin wheels on all gear assemblies and the main gear retracting into the sponsons. The fuselage was watertight, though the machine did not have a boat hull, was not really intended for amphibious use, and only landed on water in emergencies. Fuel was carried in tanks in the sponsons, with the bottom tank self-sealing to protect it from ground fire. Up to five 1,136 liter (300 US gallon) ferry tanks could be installed inside the fuselage.

The CH-53A featured the six-bladed main rotor and four-bladed tail rotor proven on the S-64. To conserve space on board naval vessels, the tail boom and the rotors folded. Sources are confusing on the tail boom and rotor folding, making it unclear if this was a feature on all S-65 variants, specifying automatic or manual folding mechanisms in an irregular pattern. It appears that folding was featured to all shipboard variants; tail boom folding was generally or always manual; and rotor folding was generally automatic.

The rotor system was initially driven by twin GE T64-GE-6 turboshafts providing 2,125 kW (2,850 SHP) each, with one engine on each side of the forward fuselage. It was later produced with the T64-GE-1 with 2,300 kW (3,080 SHP) and then the T64-GE-16 with 2,600 kW (3,485 SHP). Controls were mechanical, backed up by two independent hydraulic servo systems and an automatic flight control system (AFCS). The EAPS inlet scheme was fitted to production machines, which were also fitted with a pintle mount in a hatch on each side of the fuselage for an M-60 7.62 millimeter (0.30 caliber) machine gun, and carried 205 kilograms (440 pounds) of armor to protect the crew and vital mechanical systems.

The CH-53A could carry a crew of 4 -- pilot, copilot, crew chief, and "aerial observer" -- and 38 troops; 24 litters with medical attendants; an internal cargo load of 3,630 kilograms (8,000 pounds); or an external load of 5,900 kilograms (13,000 pounds) on the single-point sling hook. The internal cargo bay was 9.14 meters long by 2.29 meters high by 1.98 meters wide (30 by 7.5 by 6.5 feet), and featured a roller system and tie-downs built into the floor. The CH-53A was a very capable machine and it set several performance records; it could even perform loops and rolls.

* The CH-53A arrived in Vietnam in January 1967 and proved useful, eventually recovering even more downed aircraft than the CH-54, and in fact there are claims that the number of aircraft recovered paid back more to the USMC than the price of all S-65s obtained by the Marines. The S-65 was clearly much more along the lines of what the military really wanted than the S-64 and soon eclipsed it.

Heavy lifting in tropical climates demanded more power, however, and so the Marines decided to acquire an improved variant, the "CH-53D", with uprated engines, originally the T64-GE-412 with 2,755 kW (3,695 SHP) and later the T64-GE-413 with 2,930 kW (3,925 SHP); an uprated transmission to take advantage of the more powerful engines, capable of handling 5,640 kW (7,560 SHP) on two engines and 2,820 kW (3,780 SHP) on one engine; and a revised interior to permit a load of 55 troops.

Initial flight of the CH-53D was on 27 January 1969, with initial service deliveries later in that year. A total of 124 CH-53Ds were built, plus another two "VH-53D" VIP transports, with were fitted with plush accommodations and used by the Marines for the US presidential flight. The VH-53Ds were eventually replaced by Sikorsky S-70 "Presidential Hawks".

   SIKORSKY S-65 / CH-53D SEA STALLION:
   _____________________   _________________   _______________________
 
   spec                    metric              english
   _____________________   _________________   _______________________

   main rotor diameter     22.02 meters        72 feet 3 inches
   tail rotor diameter     4.88 meters         16 feet
   fuselage length         20.47 meters        67 feet 2 inches
   footprint length        26.9 meters         88 feet 3 inches
   height (tail rotor)     7.59 meters         24 feet 11 inches
   height (rotor head)     5.22 meters         17 feet 2 inches

   empty weight            23,485 kilograms    10,655 pounds
   max loaded weight       19,050 kilograms    42,000 pounds

   maximum speed           315 KPH             195 MPH / 170 KT
   service ceiling         6,400 meters        21,000 feet
   range                   415 kilometers      260 MI / 225 NMI
   _____________________   _________________   _______________________

Although aircraft nicknames are always a tricky subject, nicknames associated with the H-53 series include "Hog", "Pig", "Piggy", "BigIron", and "Shitter", the last because its engines apparently tend to run dirty and smudge up the tailboom.

Later production CH-53Ds featured a "Blade Inspection Method (BIM)" scheme to detect hard-to-spot cracks in its metal rotors. BIM involved pressurizing the interior of the rotor blades; if pressure was lost, a red indicator on the rotor blade tip was tripped. Later, the BIM system was connected to a cockpit display. BIM reduced the need to swap out rotor blades on a routine basis, and some sources hint the scheme was retrofitted to CH-53As and possibly even CH-54s.

The CH-53D served alongside the CH-53A through the rest of the Vietnam War, with both types performing a final service at the end of the conflict in performing evacuations of personnel from Saigon and Phnom Pehn. The Marines lost 19 S-65s in Vietnam, including 9 destroyed in combat and ten wrecked in accidents. The older CH-53As had all been phased out by the early 1990s, but the CH-53D remains in service. Ultimately the Marines hope to replace their S-65s with the Bell-Boeing MV-22 Osprey tiltrotor, but the Osprey has gone from obstacle to obstacle and the time frame for replacement has steadily slipped out.

In the modern era, CH-53Ds are fitted with defensive countermeasures, with an AN/ALE-39 chaff-flare dispenser containing 30 cartridges on each side of the tail boom, as well as an AN/ALQ-157(V)2 infrared countermeasures (IRCM) set. It is unclear if countermeasures were fitted in production or added later. CH-54Ds are now generally armed with twin 12.7 millimeter guns, typically the M2 / XM218 Browning, instead of the lighter M-60. Whether the more modern GECAL 50 3 or 6 barrel Gatling-type gun has been fitted is unclear, though it seems plausible as it provides a much higher rate of fire than the famously plodding, if extremely well-proven and effective, Browning.

* In 1989, some of the CH-53As being retired by the Marines were passed on to the US Air Force for training, with these helicopters redesignated "TH-53As". The TH-53As were stripped of most operational equipment and painted in USAF camo colours. The topic of the S-65 in USAF service is covered in later sections of this document.

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[3] US NAVY RH-54A & RH-54D SEA STALLION

* All but the first 32 of the CH-53As built had hardpoints for towing minesweeping gear. Following an evaluation, in 1971 the US Navy arranged for the transfer of 15 CH-53As with hardpoints from the USMC to the Navy for the "airborne mine countermeasures (AMCM)" role. Since towing a minesweeping sled requires a fair amount of power, these 15 Navy CH-53As were reengined with T64-GE-413 turboshafts with 2,930 kW (3,925 SHP) each, and redesignated "RH-53A".

The RH-53As were also fitted with rear-view mirrors to allow the flight crew to keep an eye on the minesweeping gear; twin Browning 12.7 millimeter (0.50 caliber) machine guns to detonate mines whose anchor cables had been cut; and a frame that stuck out from the rear loading ramp to keep the tow cable from snapping up into the tailboom or tail rotor. The mirrors and the frame could be easily removed when the RH-53As were used in their secondary transport role. Minesweeping gear used by the RH-53A included:

These RH-53As, aided by some USMC CH-53As that had been temporarily modified as minesweepers, performed an extended series of sorties from February through July 1973 during OPERATION ENDSWEEP, which involved the removal of mines planted in North Vietnamese waters as required by the dubious "peace treaty" signed between the US and North Vietnam in early 1973.

* The RH-53A was only intended as an interim solution until the Navy obtained the more powerful CH-53D for the AMCM role. The first RH-54D performed its initial flight on 27 October 1972 and deliveries to the Navy beginning in the summer of 1973, with a total of 30 acquired in all. Once the RH-53Ds were in service, the RH-53As were handed back to the Marines and restored to CH-53A configuration.

The RH-53D had the Browning guns, rear-view mirrors, plus cargo-ramp frame used by the RH-53A, and towed the same AMCM gear. The main improvement was fit of more powerful engines, originally the T64-GE-413A with 2,930 kW (3,925 SHP) as used on late CH-53Ds, but then the T64-GE-415 with 3,265 kW (4,380 SHP), as well as the stronger transmission system of the CH-53D. The RH-53D also featured a number other improvements over the RH-53A:

AN/ALE-39 chaff-flare dispensers were fitted to the RH-53D, possibly as a retrofit. The RH-53D could be operated in the transport and SAR roles as secondary missions.

The RH-53D did not see service in Vietnam, but it was used for clearing Israeli-laid mines from the Suez Canal and Egyptian coastal waters after the Yom Kippur / Ramadan conflict in 1973, in OPERATION NIMBUS STAR in April 1974 and OPERATION NIMBUS STREAM in July 1975. The RH-53D was also used to clear mines during the Persian Gulf convoy operations in the late 1980s, in OPERATION INTENSE LOOK and OPERATION EARNEST WILL.

The RH-53D also played a major if notorious role in OPERATION EAGLE CLAW, the ill-fated attempt to rescue hostages from the American Embassy in Teheran, Iran, on 24:25 April 1980. EAGLE CLAW was badly planned and executed. Eight RH-53Ds were assigned to the mission, to be flown in without markings, but they were obtained from regular operational units whose commanders were not informed that the machines were needed for a highly critical operation. As a result, the unit commanders passed on the RH-53Ds that they could most easily spare, meaning their hangar queens and gremlin nests. Worse, they ran into a sandstorm during insertion and three failed en route. The mission was scrubbed, but then one of the others drifted into a C-130 in the dark at the DESERT ONE site in Iran, resulting in the deaths of eight Americans. The mission was called off and all the other RH-53Ds were then destroyed or abandoned.

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[4] USAF HH-53B, HH-53C, & CH-53C

* The US Air Force liked their Sikorsky S-61R / HH-3E Jolly Green Giant long-range combat search and rescue (CSAR) helicopters very much, and so were very interested in the more capable S-65. In 1966, the USAF awarded a contract to Sikorsky for development of a minimum-change minimum-change CSAR variant of the CH-53A. The "HH-53B", as it was designated, featured:

Early HH-53Bs featured T64-GE-3 turboshafts with 2,300 kW (3,080 SHP), but these engines were later upgraded to T64-GE-7 turboshafts with 2,930 kW (3,925 SHP). Five crew were standard, including a pilot, copilot, crew chief, and two pararescuemen.

While waiting for delivery of the HH-53Bs, the Air Force obtained two Marine CH-53As for evaluation and training. The first of eight HH-53Bs performed its initial flight on 15 March 1967, and the type was performing CSAR missions with the USAF Aerospace Rescue & Recovery Service in Southeast Asia by the end of the year. The Air Force called the HH-53B the "Super Jolly". It was used for CSAR, covert combat operations, and "snagging" reentry capsules from photo-reconnaissance satellites.

* The HH-53B was essentially an interim type, with production quickly moving on to the modestly-improved Air Force "HH-53C" CSAR variant. The most visible difference between the HH-53B and HH-53C was that the HH-53C dispensed with the fuel-tank bracing struts. Experience with the HH-53B showed that the original tank was too big, adversely affecting performance when they were fully fueled, and so a smaller 1,705 liter (450 US gallon) tank was adopted in its place. Other changes included more armor and a more comprehensive suite of radios to improve communications with C-130 tankers, attack aircraft supporting CSAR actions, and aircrews on the ground. The HH-53C was otherwise much like the HH-53B, with the more powerful T64-GE-7 engines.

A total of 44 HH-53Cs was built, with introduction to service in August 1968. Late in the war they were fitted with countermeasures pods to deal with heat-seeking missiles. As with the HH-53B, the HH-53C was also used for covert operations and snagging reentry capsules, as well as snagging reconnaissance drones. A few were assigned to support the Apollo space program, standing by to recover an Apollo capsule in case of a launchpad abort, though such an accident never happened.

* In addition to the HH-53Cs, the Air Force obtained 20 "CH-53C" machines for more general transport work. The CH-53C was apparently very similar to the HH-53C, even retaining the rescue hoist, the most visible difference being that the CH-53C did not have an inflight refueling probe. Since CH-53Cs were used for covert operations, they were no doubt armed and armored, just like HH-53Cs.

The Super Jollies made headlines in November 1970 in the unsuccessful raid into North Vietnam to rescue prisoners-of-war from the Son Tay prison camp, as well as in the operation to rescue the crew of the freighter MAYAGUEZ from Cambodian Khmer Rouge fighters in May 1975. The Air Force lost 17 Super Jollies in the conflict, with 14 lost in combat -- including one that was shot down by a North Vietnamese MiG-21 on 28 January 1970 while on a CSAR mission over Laos -- and three lost in accidents.

The HH-53B, HH-53C, and CH-53C remained in Air Force service into the late 1980s. Super Jollies operating in front-line service were painted in various camouflage color schemes, while those in stateside rescue service were painted in a natty overall gray scheme with a yellow tailband. A good number of Super Jollies were converted into Pave Low special-operations machines, the subject of the next section.

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[5] USAF PAVE LOW: HH-53H / MH-53H, MH-53J, TH-53J, MH-53M

* The USAF's Super Jollies were excellent helicopters and were appreciated by the service, but they were more or less daylight / fair weather machines, and downed aircrew were often inconsiderate enough to get into trouble at night or in bad weather. A limited night / foul weather sensor system designated "Pave Low I" based on a low-light-level TV (LLLTV) imager was deployed to Southeast Asia in 1969 and combat-evaluated on a Super Jolly, but it left much to be desired in terms of reliability.

In 1975, an HH-53B was fitted with the much improved "Pave Low II" system and redesignated "YHH-53H". This exercise proved much more satisfactory, and so eight HH-53Cs were given a further improved systems fit and redesignated "HH-53H Pave Low III", with the YHH-53H also upgraded to this specification. All were delivered in 1979 and 1980. Two of the HH-53Hs were lost in training accidents in 1984, and so two CH-53Cs were brought up to HH-53H standard as replacements.

The HH-53H retained the inflight refueling probe, external fuel tanks, rescue hoist, and three-gun armament of the HH-53C; armament was typically a Minigun on each side, and a Browning 12.7 millimeter gun in the tail to provide more reach and a light anti-armor capability. The improvements featured by the HH-53H included:

The FLIR and TFR were mounted on a distinctive "chin" mount. The HH-53H could be fitted with 27 seats for troops or 14 litters. The upgrades were performed by the Navy in Pensacola, reflecting the fact that the Navy handled high-level maintenance on Air Force S-65s. In 1986, the surviving HH-53Hs were given an upgrade under the "Constant Green" program, featuring incremental improvements such as a cockpit with blue-green lighting compatible with night vision goggles (NVGs). They were then reclassified as "special operations" machines and accordingly given a new designation of "MH-53H".

* The HH-65H proved to be a good thing and the Air Force decided they wanted more of it, coming up with an "MH-53J Pave Low III Enhanced" configuration. The general configuration of the MH-53J is similar to that of the HH-53J, the major change being fit of twin T64-GE-415 turboshafts with 3,265 kW (4,380 SHP) each, as well as more armor, giving a total armor weight of 450 kilograms (1,000 pounds). There were some avionics upgrades as well, including fit of a modern Global Positioning System (GPS) satellite navigation receiver. A grab-bag of 31 HH-53Bs, HH-53Cs, and CH-53Cs were upgraded to the MH-53J configuration, in 1986 through 1990, with all MH-53Hs upgraded as well, giving a total of 41 MH-53Js.

The MH-53J went into service with the Special Operations Command (SOCOM) in 1987, which became (as far as the USAF was concerned) the Air Force Special Operations Command (AFSOC) in 1990. The MH-53J was used during the invasion of Panama and saw extensive service during the Gulf War, where it was used to insert Special Operations teams deep in the Iraqi desert to hunt for Iraqi "Scud" ballistic missiles. It has since been used in other conflicts in this era of "dirty little wars".

The Air Force has run the MH-53J fleet through a series of upgrades, including a "service life extension program (SLEP)" that not only will keep the machines in service longer, but increased their top load capacity by 45%. Another upgrade fitted the MH-53Js was a folding tail boom and automatic main blade folding for shipboard storage and air transport.

In the late 1990s, six older MH-53Js were modified for use as trainers and given the new designation of "TH-53B". 25 other MH-53Js were fitted with an improved defensive avionics suite and a datalink terminal and redesignated "MH-53M". The Air Force is expecting to replace the type with the CV-22B Osprey tiltrotor, but as mentioned that program has been moving along slowly and the MH-53M will remain in service for a few more years.

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[6] S-65 IN FOREIGN SERVICE

* The S-65 has obtained a good number of export sales. In the late 1960s, West Germany began a competition for a helicopter to replace Piasecki H-21 Flying Bananas and Sikorsky H-34s in West German Army service, and awarded a contract to Sikorsky for the "CH-53G", basically a CH-53D without refueling probe or external tanks, in June 1968. Sikorsky provided two machines directly, and then provided kits to a group led by VFW-Fokker for the construction of 20 more. Initial flight of a German-assembled CH-53G was on 11 October 1971, with the type going into West German Army service in 1973. 90 more CH-53Ds were built in West Germany with a decreasing level of Sikorsky content, for a total of 112 machines in West German service.

In the summer of 2003, the German Parliament approved an upgrade for the German Army's CH-53 fleet. The T64 engines were to be upgraded to increase power and improve reliability.

* There were a number of other foreign S-65 operators:

Sikorsky gave some thought to selling the S-65 for commercial operations, even modifying a CH-53D to an airliner demonstrator configuration under a US National Aeronautics & Space Administration (NASA) contract. This "S-65C" machine, also known as the "Ride Comfort Research Aircraft (RCRA)", was used for tests for two decades, but it did not lead to a commercial variant or commercial sales. Nobody ever managed to sell a truly heavy helicopter on the commercial market without losing their shirts on it.

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[7] S-80 ORIGINS / US MARINE & NAVY SERVICE / JAPANESE SERVICE

* Although the S-65 proved a better solution to military needs than the S-64, the S-65 still lacked adequate lifting power for really satisfactory use as a flying crane. Lifting aircraft could be troublesome, and it didn't have as much power as desired for the minesweeping role. Towing a sled could be troublesome, particularly in rough seas.

In October 1967, the Marines issued a Specific Operational Requirement (SOR-14-20) for a helicopter with a lifting capacity 1.8 times that of the S-65 that was still able to fit on amphibious assault vessels. The Navy was also interested in such a machine for the "vertical replenishment (vertrep)" role, to resupply ships at sea by air. At roughly the same time, the Army began looking for a "Heavy Lift Helicopter (HLH)" to replace the CH-54.

Sikorsky had been working on an enhancement to the S-65, which acquired the company designation of "S-80", even before issue of the requirement, with this configuration featuring a third turboshaft engine and a more powerful rotor system, and proposed this solution to the Marines in 1968. The Marines liked the idea since it promised to deliver a good solution with a minimum of delay, and funded development of testbed machine for evaluating the more powerful rotor system.

In the meantime, the Army was working on their HLH in parallel, focusing on a Boeing Vertol proposal that was something like a scaled-up Chinook, and there was political pressure for all three services to obtain a common solution. In September 1970, US Defense Secretary Melvin Laird dictated that the services would all acquire the Army HLH candidate, but the Marines and Navy protested that the Army HLH was simply too big to operate off of landing ships. This was easy to demonstrate, and so at the end of 1971 Congress gave the Marines and the Navy the approval to go their own way and acquire the Sikorsky proposal, and a contract for two "YCH-53E" prototypes was quickly issued. This was fortunate, because the Army HLH would be axed in late 1974.

* The first of the two YCH-53Es performed its its initial flight from the Sikorsky plant in Stratford on 1 March 1974. The airframe was basically that of the S-65, but with three T64-6E-415 turboshafts, the third engine being nested on the back of the machine behind the rotor shaft, the engine intake sitting to the left of the rotor shaft. The engines featured anti-icing systems. A Solar gas-turbine auxiliary power unit (APU) was fitted between the forward engine inlets for engine starting and ground power. (It is unclear if S-65s also had an APU.)

The S-80 also featured:

The S-80 could carry up to 55 troops, though it was generally assigned the heavy cargolifting role. It had an internal cargo capacity of 13,610 kilograms (30,000 pounds), and a sling load capacity of 16,330 kilograms (36,000 pounds). Sling loads could be carried by either the traditional single center-mounted cargo hook, or by a new twin cargo hook arrangement, with a hook fore and aft.

The first prototype was wrecked in a ground accident. While the prototypes were built with a wide-span, low-mounted symmetrical tailfin, flight control problems led to refitting the second machine with of a distinctive new tail assembly, with the tailfin canted to the left by 20 degrees and an inverted-gull asymmetric tailplane mounted on the right. This change was used in production S-80s.

The initial pre-production "CH-53E Super Stallion" flew on 8 December 1975. This was the first machine in the S-65 / S-80 series to feature a digital instead of analog flight control system, with the digital system used in all following S-80s. The first production contract was awarded in 1978, and service introduction followed in February 1981. The USMC built up their inventory of the machine and found it very useful for aircraft recovery, as well as transport of artillery, light armored vehicles, and the like. Despite its size, its speed and agility were regarded as outstanding. The digital flight control system prevented the pilot from overstressing the machine. The CH-53E provided excellent service during the Gulf War. The US Navy also liked the CH-53E and acquired it in small numbers for shipboard resupply. The Marines and Navy acquired 177 between them.

   SIKORSKY S-80 / CH-53E SUPER STALLION:   
   _____________________   _________________   _______________________
 
   spec                    metric              english
   _____________________   _________________   _______________________

   main rotor diameter     24.08 meters        79 feet
   tail rotor diameter     6.10 meters         20 feet
   fuselage length         22.35 meters        73 feet 4 inches
   footprint length        30.19 meters        99 feet
   folded length           18.44 meters        60 feet 6 inches
   height (tail rotor)     8.66 meters         28 feet 5 inches
   height (rotor head)     5.32 meters         17 feet 6 inches

   empty weight            15,070 kilograms    33,225 pounds
   max loaded weight       31,640 kilograms    73,500 pounds

   maximum speed           315 KPH             195 MPH / 170 KT
   service ceiling         5,640 meters        18,500 feet
   ferry range             2,075 kilometers    1,290 MI / 1,120 NMI
   _____________________   _________________   _______________________

CH-53Es could carry twin-gun armament and were fitted with the AN/ALE-39 chaff-flare dispensers, just as with the RH-53D. Most or all CH-53Es were later refitted with cockpit lighting for NVG compatibility; a Hughes AN/AAQ-16 FLIR or "Helicopter Night Vision System (HNVS)", on a somewhat "tacked-on" mount on the left side of the nose; new radios and a GPS receiver; and pilot seats with improved crash protection. Interestingly, apparently CH-53Es were evaluated with air-to-air missiles (AAMs) for self-defense, with one Sidewinder or two Stinger AAMs carried at the end of each sponson. Details of the evaluation are unclear and this fit has apparently never been used operationally.

* The Navy was very interested in the S-80 for the AMCM role, and acquired a variant optimized for that task, designated the "S-80M" or "MH-53E Sea Dragon". It differs from the CH-53E most visibly in having absurdly enlarged sponsons to provide substantially greater fuel storage and endurance. It also retained the inflight refueling probe of the CH-53E, and could be fitted with up to seven 1,136 liter (300 US gallon) ferry tanks internally, though it can't carry external tanks.

The MH-53E digital flight-control system includes features specifically designed to help towing minesweeping gear. The Sea Dragon is equipped with mine countermeasures systems like those of the RH-53D, including the twin machine guns, with modern additions such as the AN/ALQ-160 acoustic countermeasures system; an AN/ALQ-166 magnetic mine hydrofoil sled; and a Northrop "Airborne Laser Radar Mine Sensor (ALARMS).

The initial "YMH-53E" prototype was a conversion of a pre-production CH-53E, without the oversized sponsons, and performed its first flight on 23 December 1981. The first pre-production machine performed its initial flight on 1 September 1983, with service deliveries beginning in June 1986 and service introduction in April 1988. The Navy obtained a total of 46 Sea Dragons, with these machines operating almost exclusively in the AMCM role, since the Navy had acquired CH-53Es for the transport role. Most or all of the surviving RH-53Ds were also converted back to the transport role.

There was a plan at one time to acquire six S-80s as VIP transports for the Presidential flight, with these machines to be designated "VH-53F". However, the contract was cancelled and no VH-53Fs were ever built.

* Although Sikorsky promoted an "S-80E" export variant of the CH-53E, the "S-80M-1" export variant of the MH-53E is the only variant of the S-80 series that found a foreign buyer, with 11 obtained by the Japanese Maritime Self-Defense Force (JMSDF). The initial buy was ordered in 1983, but due to political problems the first one was not delivered until 1989. The Japanese Sea Dragons are very similar to their US Navy equivalents, but lack the inflight refueling probe. The Japanese Sea Dragons have a secondary transport capability and may be assigned disaster-relief missions, which are a high priority for the Self-Defense Forces.

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[8] S-80 UPGRADES

* The US Marine Corps are currently planning a service-life extension program to keep 140 of their 160 CH-53Es in operation until at least 2025. Sikorsky has proposed a new version, tentatively designated the "CH-53X", and the Marines are interested. The main improvements in the CH-53X would be new engines and cockpit layout. The current candidate for a new engine is the Rolls-Royce Allison AE1107, which is also used on the Osprey. General Electric would also like to bid on a new engine. The new engines would require modifications of the intakes and exhaust, and addition of full-authority digital engine control (FADEC).

The new cockpit could be derived from either the V-22, or the new upgraded Bell UH-1Y Huey, which will be in service with the Marines in a few years. Other possible changes for the CH-53X would be all-composite rotors, an all-electric blade fold scheme, and an improved external cargo handling system.

Sikorsky has also pitched an improved CH-53 to the US Army, with the improved machine similar to the proposed CH-53X, but would incorporate an even more modern turboshaft engine, now being developed as part of the Pentagon's "Integrated High-Power Turbine Engine Technology" program. The Army could upgrade CH-53Es being retired by the Marine Corps, or could buy new-build machines. However, new-build machines may be hard to get if the Army waits too long, since the CH-53 production line is scheduled to be shut down once the eight final production aircraft are delivered to Turkey.

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[9] VARIANT SUMMARY

* The following table gives the types and numbers of Sikorsky giant helicopter variants:

   variant built converted  notes 
   _____________________________________________________________________

   S-64 SKYCRANE:
   _____________________________________________________________________

   S-60        1         -  Sikorsky piston-powered demonstrator.
   S-64        3         -  Three protos, one for West Germany.
   S-64E     ~10         -  Commercial variant. 
   YCH-54A     1         -  US Army evaluation machine.
   CH-54A     54         -  US Army production machines.
   CH-54B     37         -  More powerful US Army variant.

   subtotal  106            Including S-60 demonstrator.
   _____________________________________________________________________

   S-65:
   _____________________________________________________________________

   YCH-53A     2         -  S-65 prototypes.
   CH-53A    141         -  USMC transport.
   RH-53A      -        15  CH-53As loaned to US Navy for AMCM.
   TH-53A      -         ?  CH-53As passed on to USAF as trainers.

   HH-53B      8         -  USAF Super Jolly CSAR machines.
   HH-53C     44         -  Improved USAF Super Jolly CSAR machines.
   CH-53C     10         -  USAF transports, similar to HH-53C.

   CH-53D    124         -  More powerful USMC transport.
   VH-53D      2         -  CH-53D VIP transports.
   RH-53D     36         -  AMCM variant, 30 for USN, 6 for Iran.

   YHH-53H     -         1  HH-53B modified with all-weather avionics.
   HH-53H      -        10  All-weather Super Jolly upgrades.
   MH-53H      -         8  Upgraded HH-53H.
   MH-53J      -        41  Improved MH-53H configuration machines.
   TH-53B      -         6  Old MH-53Js converted to trainers.
   MH-53M      -        25  MH-53Js with further improvements.

   CH-53G    112         -  CH-53D for German service.
   S-65C-2     2         -  CH-53Oe for Austrian service.
   S-65C-3    33         -  HH-53C for Israeli service.
   S-65-?      8         -  Machines for Turkish service.

   subtotal  522            
   _____________________________________________________________________

   S-80:
   _____________________________________________________________________

   YCH-53E     2         -  S-80 prototypes.
   CH-53E    177         -  Transports for USMC & US Navy. 
   MH-53E     46         -  Sea Dragon AMCM machines for US Navy.
   VH-53F      -         -  VIP transport, not built.
   S-80M-1:   11         -  Sea Dragons for Japanese JMSDF.

   subtotal  236            
   _____________________________________________________________________

   TOTAL     864
   _____________________________________________________________________

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[10] COMMENTS, SOURCES, & REVISION HISTORY

* As is so often the case, I thought this would be a fairly straightforward writeup, and it turned out to be about twice as long as I expected it to be. I can only recall seeing an S-65 once, or at least I think it was an S-65. I was down at Fort Hood, Texas, in 1973 and 1974, and was wandering around on the post when I got to witness a huge helicopter taking off. I wasn't that familiar with the Sikorsky family at the time and all I knew was that it was a Sikorsky Green Giant of some sort, but though the memory is vague I don't think it was an S-61R. I do remember the awesome threshing of its big main rotors.

I also have vague, if much more recent, memories of spotting civilian S-64s flying around above the woods while I was driving through the mountains of Montana. However, I am unable to recall any of the details. Incidentally, those readers who took notice of the term "gremlin nest" in the text should be aware that this is not military slang -- it's my own little phrase.

* Sources include:

* Revision history:

   v1.0.0 / 01 jun 04 / gvg
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