Back Sikorsky S-56 / CH-37 Mojave / HR2S

Sikorsky S-56

The Sikorsky S-56 came into being as an assault transport for the U.S. Marine Corps, although some 60 per cent of those eventually built were to meet U.S. Army orders. The original requirement was for an assault transport helicopter capable of air-lifting 26 troops and their equipment. The S-56 was Sikorsky's first twin-engined helicopter, although the traditional single main rotor layout was retained, this being a 5-blade unit designed to be able to sustain the aircraft in flight with one blade shot away. For several years the S-56 was the western world's largest and fastest military helicopter, and held two height-with-payload records from 1956-59. It was also the first production helicopter to have a retractable main undercarriage, this being housed at the extremities of the small stub wings in the pods containing the engines. Loading of the aircraft was via clamshell nose doors, giving access beneath the flight deck to the 53.80m3 cabin in a similar manner to the fixed-wing Bristol 170 Freighter. A winch capable of hoisting 907kg at a time was fitted in the cabin roof to assist the loading of cargo.

The U.S. Navy placed an order in May 1951 for a prototype XHR2S-1, which was flown for the first time on 18 December 1953. The first of sixty HR2S-1's was flown on 25 October 1955, deliveries to Marine Corps Squadron HMX-1 starting in July 1956. A small batch of these aircraft were modified as HR2S-1W patrol aircraft with a huge AN/APS-20E search radar under the nose and additional crew members for radar picket duties. In 1954 an HR2S-1, redesignated YH-37, was evaluated by the U.S. Army, from which followed orders for ninety-four similar aircraft as H-37A Mojave for general transport duties.

Production of the S-56 ended in May 1960, but Sikorsky were engaged until the end of 1962 in converting all but four of the H-37A's to H-37B (later CH-37B) standard. Improvements in this version included the installation of Lear auto-stabilisation equipment and the ability to load and unload while the helicopter was hovering. The Navy and Marine S-56's became CH-37C's under the 1962 designation system. Some later production S-56's had 2100hp R-2800-54 engines.

The S-56's rotor and transmission systems were utilised in the development of the abortive Westland Westminster and Sikorsky's own S-60 and S-64 crane helicopters, but hopes of selling the S-56 on the commercial market were not realised, due mainly to the high operating costs of a piston-engined machine of this size, and a proposal to fit Lycoming T55 gas turbines was not adopted.

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

Sikorsky S-56 / CH-37 Mojave / HR2S

Immediately after the S-55 had entered production, Sikorsky began working on the design of a larger helicopter, intended as an assault transport for the Marines. A twin-engine solution was chosen, and to save cabin space, it was decided to house the two large radial engines in outboard nacelles, from which two drive shafts linked up directly with the reduction gear assembly which drove the big five-blade metal rotor. The large cargo bay had a hoist capable of lifting a one tonne load. The main landing gear wheels retracted, but the tailwheel was fixed.

Some of the 60 aircraft ordered by the Marine Corps were converted into radar patrol craft (military designation HR2S-1W), with a bulbous dielectric radome under the nose, but this transformation was unsuccessful. The Army ordered 91 aircraft, designated H-37A "Mojave".

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

Sikorsky S-56 / CH-37 Mojave / HR2S

Sikorsky originally developed the Model S-56 twin-engined heavy lift helicopter in response to a 1950 Marine Corps requirement for an assault transport able to carry twenty-three fully equipped troops. In 1951 the Navy ordered four XHR2S-1 prototypes for USMC evaluation, and the first of these made its maiden flight in December 1953. In 1954 the Army borrowed one of these preproduction machines, designated it the YH-37, and subjected it to rigorous operational and maintenance evaluations before returning it to the Marines. On the basis of the large helicopter's excellent showing during the Army evaluation, Sikorsky was in late 1954 awarded a contract for nine production H-37A Mojaves. The first of these reached Fort Rucker during the summer of 1956, at about the same time the HR2S-1 naval variant was entering regular Marine squadron service. The Army subsequently placed orders for a further 85 H-37As, and all ninety-four aircraft were delivered by June of 1960.

At the time of its introduction into the Army inventory the H-37A was the largest helicopter in U.S. military service. It was also Sikorsky's first multi-engined helicopter, and in developing it the company chose to break with then-current industry practice by using a single five-bladed main rotor instead of two fore- and aft-mounted tandem rotors. The Mojave's designers chose not to locate the aircraft's engines in the upper section of the fuselage, as was common with most other contemporary heavy lift helicopters, but instead placed the 1900hp Pratt & Whitney radials in nacelles fixed to the ends of short shoulder-mounted stub wings; the engine nacelles also accommodated the machine's fully retractable, twin-wheeled main landing gear legs. The H-37's innovative engine arrangement gave the craft an unobstructed cargo bay of nearly 1500 cubic feet, large enough to carry three Jeeps, twenty-four stretchers, or up to twenty-six fully-equipped troops. The Mojave's nose section was equipped with large clam-shell doors which allowed vehicles to be driven straight into the cargo area, with the cockpit placed above and slightly to the rear of the doors to ensure good visibility forward and to the sides. The H-37's tailboom was very similar in appearance to that of the H-34, in that it sloped downward toward the tailwheel and ended in a sharply upswept vertical tail unit carrying a four-bladed anti-torque rotor.

In 1961 Sikorsky began converting the Army's H-37As to -B model standard by installing automatic flight stabilization systems, crash-resistant fuel cells and modified nose doors. All but four -A model aircraft were eventually converted; in 1962 these were redesignated CH-37A, while the modified machines became CH-37B. Records indicate that the Army also evaluated one of the Navy's two radar-equipped HR2S-1W airborne early warning (AEW) aircraft. This machine (BuNo 141646) retained the AEW variant's large chin-mounted radome and AN/APS-20E search radar, and was operated in Army markings and two-tone 'Arctic' paint scheme.

The CH-37 was developed just prior to the widespread adoption of the turbine engine as a standard helicopter powerplant and, as a result, the type was forced to rely on larger, heavier and less powerful pistons. This did not prove to be an insuperable handicap, however, for the Mojave ultimately proved to be a more than capable heavy lifter when properly employed. Perhaps the best illustration of such employment occurred in Southeast Asia during the summer and fall of 1963. In June of that year four CH-37Bs were temporarily deployed to Vietnam to assist in the recovery of downed U.S. aircraft. By the following December the Mojaves had recovered an estimated $7.5 million worth of equipment, most of which was sling-lifted out of enemy-dominated areas virtually inaccessible by any other means. That the CH-37 did not see more extensive service in Vietnam is primarily the result of its replacement in the Army inventory by the turbine-powered Sikorsky CH-54 Tarhe, a machine that weighed slightly less than the CH-37 but which could carry nearly four times as many troops or five times as much cargo. The last CH-37 was withdrawn from Army service in the late 1960s.

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

Sikorsky S-56 / CH-37 Mojave / HR2S

Developed to meet a US Marine Corps requirement for a large assault helicopter to carry 26 troops or military vehicles, for which clamshell nose-opening doors were provided, the Sikorsky S-56 was the first Sikorsky twin-engined helicopter. Two 1417kW Pratt & Whitney R-2800-50 Double Wasp engines (1566kW R-280054s on late production aircraft) were mounted on stub wings, and the nacelles also housed the main legs of the retractable landing gear, the first application of this feature in a production helicopter. The prototype XHR2S-1 flew on 18 December 1953 and 60 production machines were delivered from July 1956. Two HR2S-1W . helicopters were converted for US Navy early warning operations with AN/APS-20E radar under the nose. US Army evaluation of an HR2S-1, under the designation YH-37, resulted in orders for 94 H-37A Mojave helicopters which went into service, initially with 4th Medium Helicopter Transportation Company, in February 1958. Modernised H-37As redesignated H-37B (later CH-37B), were redelivered to the US Army from 1961.

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


- Mojaves were replaced by the CH-54 Tarhe, which weighed less but could lift five times as much cargo as the CH-37.

- In all, 150 S-56s were built; a prototype, 55 for the USMC and 94 for the Army.

- 1959 saw the first overseas H-37 deployment, by the Army to Germany.

- Army H-37As entered service with the 4th Medium Helicopter Transportation Company in February 1958.

- The H-37A had a fuselage capacity large enough to hold three Army jeeps.

- The Army briefly evaluated one of the two HR2S-1Ws in 'Arctic' colours.

Photo Gallery 

An Army H-37 sits in the Arizona desert with its clamshell nose doors open and a jeep 4x4 light truck driving out. The Marines were able to operate these relatively large aircraft from helicopter carriers as well as from shore bases and in the field.

A U.S. Marine Corps HR2S-1 twin-engine helicopter lifts an experimental automatic artillery weapon weighing 3,000 pounds. Twin external drop tanks are also fitted. This was Sikorsky's first helicopter with twin engines, which, mounted externally, allowed for maximum internal cargo space.

Sikorsky S-56

Technical data for S-56

Engine: 2 x Pratt & WHitney R-2800-54 turboshaft, rated at 1565kW, main rotor diameter: 21.95m, fuselage length: 26.80m, height: 6.71m, take-off weight: 14074kg, empty weight: 9457kg, max speed: 209km/h, service ceiling: 2652m, range: 235km

Comments1-20 21-40 41-60 61-80 81-100
Willie Mahan, e-mail, 23.01.2022reply

I was a Crew Chief on CH 37's in Korea in 65-66 with the 19th Trans Co. Before going to Viet Nam with the 119th AHC. When I came home from my Viet Nam I worked for Southern Airways in the test flight section. And joined the Texas Army National Guard as a Platoon Sgt / Crew Chief on CH 37's for 2 years before we got CH 47A . Then I went to work full time for the guard (May 72 - Dec 2004). We deployed to Desert Storm . I retired as First Sgt.

Willie Mahan, e-mail, 23.01.2022reply

I was a Crew Chief on CH 37's in Korea in 65-66 with the 19th Trans Co. Before going to Viet Nam with the 119th AHC. When I came home from my Viet Nam I worked for Southern Airways in the test flight section. And joined the Texas Army National Guard as a Platoon Sgt / Crew Chief on CH 37's for 2 years before we got CH 47A . Then I went to work full time for the guard (May 72 - Dec 2004). We deployed to Desert Storm . I retired as First Sgt.

Jim Settle, e-mail, 15.08.2020reply

Last of the Deuces in South Vietnam. 1St MAW, MAG16, Sub Unit One at Marble Mountain just outside of Danang. Commanding Officer was Major Richard Hawley. About 54 years ago. I was 18.

Stephen Sanders, e-mail, 21.06.2020reply

I was a Crew Chief on an H-37 Mojave at Ft. Benning from 1956-1959. I applied to the VA for disability for hearing loss and tinnitus due service related high H-37 noise level. Turn down once, applying again. Please help me fight the VA. Anybody else have similar experience?

Don Cunneen, e-mail, 21.04.2020reply

I was in the 4th av co from 1967 thru 1968 in the signal shop as the radio teletype operator. I remember the company clerk was Mike Merrill. Wondering if anyone else is from those days.

Anonymous, 12.02.2022 Don Cunneen

Don, I flew in the 90th Avn Co in Illesheim your sister company. I am looking for some flight crew that recall one of your Mojaves that crashes i believe in 67 or 68 that could fill in information for me please i found out the flight engineer was paralyzed and perhaps 12 years back. Here is my info
Paul Sanders


Donald Nelson Gatewood, e-mail, 21.04.2020reply

Does anyone remember about the mid to late 1960's when about a dozen CH-37's were sold, transported aboard a U. S. Navy carrier to South Korea? My father was in charge of the transfer and accompanied the helicopters from the West Coast to S. Korea. My brother has a few pictures of the helicopters wrapped in white water proof wrapping onboard the carrier.

Walt Woodrow Atwood, e-mail, 05.01.2022 Donald Nelson Gatewood

I sent you an email from this website. Did you receive it????
Walt Atwood


Donald Nelson Gatewood, e-mail, 21.04.2020reply

Does anyone remember about the mid to late 1960's when about a dozen CH-37's were sold, transported aboard a U. S. Navy carrier to South Korea? My father was in charge of the transfer and accompanied the helicopters from the West Coast to S. Korea. My brother has a few pictures of the helicopters wrapped in white water proof wrapping onboard the carrier.

Walter Woodrow Atwood, e-mail, 30.12.2021 Donald Nelson Gatewood

PS: I do have a few pictures from my tour with the 19th Trans I am willing to share. The ship that transported us was a the USNS CORE. It was a flattop and had also taken a boatload of H-21's to Korea before us, as I suppose many more similar missions.


Walter Atwood, e-mail, 30.12.2021 Donald Nelson Gatewood

I joined the Army in 1961 for helicopter mechanic training. I ended up being trained on the CH-37 at Ft Rucker. Was assigned to the 19th Trans at Fort Benning. We deployed with 16 Mojave's to Korea in 62. I was a PFC at the time. Served my 13 months and extended in Korea until my DEROS. I remember your father and a few other of the pilots whom I had a high regard for. I was there when they sought volunteers to take four of the helicopters to Viet Nam. One of my closer friends was Marshall J. Angel who lost his life there when one of the ships was shot down. I can't tell you how many games of Pinochle I played against him and his best friend Bobby Summers, but it was a lot. They were good.
After returning from Korea, I reenlisted and was assigned to Lakehurst, NJ where the labs from Ft. Monmouth had their aviation detachment. The "Guppy", modified for a large radome, was there and the reason for my assignment. Probably didn't fly over a few hours while I was assigned there. Went to flight school after that which started a whole new episode of my career. I loved the Mojave. Great helicopter and rewarding to work on. All much to do with the great NCO's and Pilots in the unit.
Walt Atwood


Donald Nelson Gatewood, e-mail, 21.04.2020reply

My father was CW4 Clarence N. Gatewood. He was stationed at Illeshiem, Germany. I was 12 yo at the time and remember Germany well. I also remember him flying at the White Sands Missile Range retrieving missiles from mid air. He went on to pilot CH-47's and CH-54's during to separate tours to Vietnam. My father retired in Albuquerque, New Mexico in 1977 where he and my mother lived until his passing in 2004.

H D Cotta, e-mail, 12.03.2018reply

I flew CH-37B in the 4th AVN from late 69 until we flew the last one on active duty to Coleman Barracks where it was turned in Sept /Oct 70. Great old aircraft, and some nice people.

Paul Sanders, e-mail, 12.02.2022 H D Cotta

H D Cotta, I was a flight engineer on Ch37 Mojave's but with 90th AVN Co out of Illesheim, Germany. I am looking for flight crew member or someone that recalls one of the 4ths Avn Mojaves crashing in 67 or 68. Please contact me.
Paul Sanders


Tom Palshaw, e-mail, 13.02.2021 H D Cotta

I was stationed in Finthen Germany with the 245th Trans. I arrived in 1969. There was a CH-37 in the hangar. It had been there for 6 months before I got there and flew out 6 months after I arrived. We all stopped to watch it leave. The New England Air Museum had one but sadly it was destroyed in the tornado of 1979.


Bob Walker, e-mail, 03.02.2018reply

19th Avn Co 66-68 Flight line driver part time dispatch mail room clerk mess clerk 2 1 /2 driver for mess hall. CWO Kanode and CWO Cox were guys I would do anything for. Still fond memories of my 18 mo in country.

Lynn Miller Sp 4, e-mail, 28.12.2017reply

Worked the flight line off an on from 1962-1964. 54th Tans Co. 154th Det. Ft. Sill, Ok. Much air time. also Drove jeep for HQ. 1st Sgt. Orr. Have been looking for Sp 5 Robert "shorty" Sanders Crew chief from Georgia. Sp 4 Sam Stamper, from Ky or Tn?? We flew to Texas to pick up Air Force wrecked air planes in the desert. Remember war game near Darlington NC we were working with blue army and the red army to trasport eather or. Many other great times.

gary haas, e-mail, 17.11.2017reply

I was in the 4th 1964 to 1966 1st Drunckenenmiller CO major Nichols,Hanau Dachau,Schliesheim ,Munich,Germany were different towns we billet.On flight status flew alot on the 37 never let us down !

Tom Walker, e-mail, 03.08.2020 gary haas

I meant Schleisheim, when I rotared back to Germany I then went to Nelligen Barrecks


Tom Walker, e-mail, 03.08.2020 gary haas

Do remember George PIO from Hawaii. I was assigned to the 4th in 1965 thru June 1966 when I was reassigned to the 196th in Ft. Sill which left for for VN as a unit. In the Munich where we had barrack there was myself, George Pio and one other that I can't recall his name but he was given a GI shower because he was so nasty. When we arrived at the Nelligen barrack I you, myself and George share a room.
My phone number is 417 207 1098


James P Landers, e-mail, 28.08.2017reply

I was stationed in Hanau Germany, Fligerhorst,I was a company clerk serving under SGT 1st Class Perry R Druckenmiller & Major Roland Nichols. I was in the 4th Avaitation Company / 152 Detatchment & the 8th Aviation Battalion. We moved the company & H27 Mohjaibe aircraft to Schliesheim air field, Munich Germany. Our company was transferred to Vietnam and anyone with 90 days of duty left went to Vietnam and anyone with less than 90 days went stateside. I had 62 days left in my tour. I roomed with Keer and Guy McCabe & had a fried name Felton Joshua. I shipped over and back on the General Darby with Charles Taucer from LA and we became great friends. I had many other great and dear friends. I stayed in contact with SGT Druckenmiller who lived in Emmaus PA and we stayed in contact until his death. We had 18 H37's and two Bells in the company. I opened the hanger every morning, made coffee for all the Warrant Officers, did morning reports, made sure that every soldier in the company got a Good Conduct Metal when he left our unit and went stateside. I did the duty roster for KP and Air Field Guard etc. etc,

Bob Craig, e-mail, 20.02.2017reply

I was in 19th Trans at Ft Benning, Korea 1962 o via the Core. Mr Gatewood was a pilot during this time. Rotated back in 1963. Great period.

doug menzhuber, e-mail, 18.09.2016reply

Worked on the ch-37 will I was stationed in Germany from 1963 to 1965.

otis richardson, e-mail, 05.04.2016reply

ch 37 995

russell gilbert, e-mail, 08.03.2016reply

served /army /4th avn co nellingen germany nov 65to nov.68 looking for other crew chief /flight engineers ch37 have hearing loss /looking for e-mails &names of other-crew members w /same problem. applied for disability /turned down 1time /reason given -not servise connected. thanks russ gilbert @

Joe Boyko, jr., e-mail, 28.02.2016reply

I just found a large photo album from when my father was stationed in Bamberg Germany, 1958-63, 100th lt truck company (road-runners). Several photos of H-37's with my father, one, with standing on the landing gear. My father passed away when I was 11 years old, so I never got to hear anything from his years in Germany. My mother just went into a retirement apartment, so she gave me the album she discovered while moving from her house. we'll thanks to this site, I know what model bird it is.

william r kinstler, e-mail, 27.02.2016reply

I was a crew chief on the h-37 b mojave at the 19 th transportation co. 1964 and part of 1965 tail no was 655 Flight engineer was jim holzer we recovered the remains of the two crew members grahm and ely whos chopper tail no 640 crashed they bunked in the same hut that i did it was a sad day for sure . After korea i was stationsed at fort bliss texas but lived and worked at Holloman air force base started out as crew chief them was flight engineerwe recovered missels that were launches ad landed in dessert White Sands Missel Range hung out in town outside base ALAMOGORDO New Mexico. Got discharged got married then moved back to ohio Had the pleasure of meeting alot of great people and seeing alot of places.

Russell Gilbert, e-mail, 12.02.2016reply

I was in Germany (Nellingen Concern) 4th AV from 1966-68. I was Crew chief and also flight engineer on CH 37's. Looking to find other who was in during that time frame. I have a serious hearing problem and need some info as well. Thank you!!

Paul Sanders, e-mail, 12.02.2022 Russell Gilbert

Russell, i also was a flight engineer on ch37 Mojave's but with the 90th Avn Co in Illesheim,Germany . I am looking for someone who can recall and give me info on one of you 37's that crashed in 67 or 68 . If you or you know some on have them get in contact with me. Oh and yes I do believe anyone that flew on a Mojave we all have hearing loss they didnt give me anything on my claim either.
Paul Sanders


Stephen Sanders, e-mail, 21.06.2020 Russell Gilbert

Please see my new comments related to hearing disability.


1-20 21-40 41-60 61-80 81-100
Do you have any comments ?

Name   E-mail

Virtual Aircraft Museum

All the World's Rotorcraft