v1.1.1 / chapter 2 of 2 / 01 may 10 / greg goebel / public domain
* The success of the twin-engine S-65 led to consideration of a derivative with three engines, which emerged as the "S-80". It was also very successful, and remains in production in the 21st century.
* 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 through 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 could still 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. 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 giant Army HLH was simply too big to operate off of landing ships. That was obviously true on the face of it, 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. The Army HLH would be axed in late 1974.
* The first of the two YCH-53Es performed 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-GE-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, and 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. Although 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 preproduction "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; the digital system would be used in all following S-80s. The initial production contract was awarded in 1978, with service introduction following in February 1981. The USMC built up 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, thanks to its excess of power 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
S-80s 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 differed 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 couldn't carry external tanks.
The MH-53E digital flight-control system included features specifically designed to help tow minesweeping gear. The Sea Dragon was 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 was 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 were very similar to their US Navy equivalents, but lack the inflight refueling probe. The Japanese Sea Dragons had a secondary transport capability and could be assigned disaster-relief missions, which are a high priority for the Self-Defense Forces.
* The US Marines have obtained improved armament for their CH-53Es, purchasing a quantity of M3M GAU-21 12.7 millimeter machine guns from FN Herstal of Belgium. The GAU-21 could fire all available 12.7 millimeter ammunition, while offering a higher rate of fire and greater reliability than the venerable Browning M2. The Marines have plans to use the M3M GAU-21 on their other helicopters. In another upgrade program, Marine CH-53Es are being fitted with an AN/AAQ-29A forward-looking infrared (FLIR) imager with three levels of zoom magnification, for use in piloting at night or in bad weather.
The Marines had been planning to upgrade most of the their CH-53Es to keep them in service, but this plan stalled. Sikorsky then proposed a new version, originally the "CH-53X", and in early 2006, the USMC signed a contract for 156 machines as the "CH-53K", with the order later expanded to 200. The Marines are planning to start retiring CH-53Es in 2009 and need new helicopters very quickly. Flight testing of the CH-53K is expected to begin in 2011, with introduction to service in 2015 and final deliveries in 2022.
The CH-53K is a general redesign of the S80. The main improvements are new engines and cockpit layout. The engines will be GE38-1B turboshafts providing 5,595 kW (7,500 SHP); they will require design modifications of the helicopter's intakes and exhaust, and will be complemented by a new elastomeric hub system and composite rotor blades. The end result is expected to be much improved "hot and high" operation.
The new cockpit will be based on the "Joint Interoperable Cockpit", which defines a digital "glass" cockpit scheme like that of the Bell UH-1Y Huey, now going into USMC service. Other changes for the CH-53K include an improved external cargo handling system, survivability enhancements, and improvements to extend service life. The CH-53K will have over twice the lift capacity and radius of action of the CH-53E, and will have cargo hold 30 centimeters (a foot) wider to allow it to carry a Humvee vehicle internally. However, the CH-53K will feature new stubby composite sponsons to cut overall width by 1.83 meters (6 feet), giving the machine a narrower footprint for shipboard operations.
* 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.
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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 - 6 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.
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.
subtotal 514
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S-80:
_____________________________________________________________________
YCH-53E 2 - S-80 prototypes.
CH-53E 177 - Transports for USMC & US Navy.
CH-53K - - Future S-80 for USMC.
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
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TOTAL 856
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* 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
v1.0.1 / 01 may 06 / gvg / Cleanup, CH-53K.
v1.0.2 / 01 mar 08 / gvg / Minor update.
v1.0.3 / 01 apr 09 / gvg / Minor corrections.
v1.1.0 / 01 dec 09 / gvg / Went to two chapters, added corrections.
v1.1.1 / 01 may 10 / gvg / Minor update.
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