Marine Corps Rotary Aircraft
During the early stages of helicopter development, when helicopters were able to lift just slightly more than their own weight, the military services were eagerly seeking to obtain a variety of larger, more useful helicopters. The youthful helicopter industry expressed optimism, although at times unrealistic, in its ability to meet the military requirements. The development of the helicopter program within the Marine Corps was sparked by the foresight and imagination of the officers of the period. While early helicopters provided stepping stones for an orderly progression of the program, the slowness of the technical advances and the periods of financial austerity after World War II and Korea prevented the Marine Corps from developing the vertical envelopment concept as rapidly as desired. The program gained interest and momentum, however, as a result of the success of helicopters in Korea.
The commissioning of Marine Helicopter Squadron 1 (HMX-1) in 1947 at Quantico, Virginia, is often cited as the official beginning of rotary-winged aviation within the Marine Corps. Interest by the Marine Corps in the capabilitie s and potentialities of rotary-winged machines, however, dated back some 15 years prior to the commissioning of HMX-1. It was in the early 1930s that the Marine Corps evaluated the Pitcairn OP-1 autogyro to determine its potential military value. Field tested in Nicaragua during 1932, the four-bladed, stubby-winged aircraft was found suitable only for liaison purposes and medical evacuation of the lightly wounded. Considered by those in Nicaragua as unsafe to fly when carrying loads in excess of 200 pounds, the OP-1 soon disappeared from active Marine Corps inventory.
The world's first practical helicopter appeared in 1937 in Germany. This was the Focke-Achgeles 61a which had two main rotors mounted side-by-side on outriggers extending from an airplane-type fuselage. The FA-61 had good control; it was once flown inside a 100-by-300-foot exhibition hall in Berlin by a woman pilot, Henna Reitsch. In 1939 Igor I. Sikorsky, a Russian-born aircraft designer and builder, successfully test flew the first practical helicopter in the Western Hemisphere. This was the Vought-Sikorsky 300 (VS-300), a 28-foot, 3-bladed main rotor helicopter with an open cockpit and powered by a 4-cylinder, 75-horsepower engine.
After the disappointing performance of the auto-gyro during the 1930s, Marine Corps interest in rotary-winged aircraft was not fully revived until 1943. During that year Marine officers from Division of Aviation (DivAvn), Headquarters Marine Corps (HQMC) sat as members of a joint Navy-Coast Guard-Marine Corps board to discuss formation of a program for the use of Sikorsky R-4 and R-6 helicopters. It was not until June 1946, however, that the first official action to institute a Marine Corps helicopter program began.
While Army aviation had been growing since before the end of the Second World War, it was the Marine Corps which first produced systematic doctrine for the employment of the new rotary-wing technology. The Corps began to study the use of helicopters in response to its observations of the CROSSROADS nuclear tests at Bikini Atoll in the Marshall Islands in 1946. These indicated that naval forces would be very vulnerable to nuclear attack unless widely dispersed, but such dispersal would preclude the Marines' primary mission-amphibious assault-at least by conventional means. The Marines set out to resolve this problem, lest they be left without a raison d'etre, and found their answer in the speed and range of the helicopter.
Lieutenant General Roy S. Geiger, Commanding General, Fleet Marine Forces, Pacific (CGFMFPac) viewed the atomic bomb tests at Bikini Lagoon as the Commandant's personal representative. In his report of 21 August 1946, he expressed to the Commandant his opinion concerning the effects the atomic bomb might have on Marine Corps doctrine during the post-World War II period. General Geiger stated that "since our probable future enemy will be in possession of this weapon, it is my opinion that a complete review and study of our concept of amphibious operations will have to be made." General Geiger went on to say, "It is quite evident that a small number of atomic bombs could destroy an expeditionary force as now organized, embarked, and landed . . . I cannot visualize another landing such as was executed at Normandy or Okinawa."
Marine Commandant, General Alexander A. Vandegrift, therefore, ordered the Marine Corps School (MCS) to begin work on establishing doctrine for the use of helicopters in amphibious operations. The Commandant acted swiftly by referring General Geiger's letter to a special board composed of three major generals, staffed with a Secretariat of three officers. The three-member Secretariat agreed that the mass destructive capability of the atomic bomb and the vulnerability of a massed amphibious landing force made dispersion a necessity - but only at the risk of defeat through slow and piecemeal commitment of forces ashore. In order to disperse the landing force sufficiently and still, equally important, have a reconcentration of forces at the point of contact with the enemy, a new mode of assault was needed as a supplement to the existing amphibious landing craft.
To solve this problem, the committee considered a variety of means to achieve a rapid buildup of assault forces ashore including transport aircraft, gliders, and parachutists. Transport aircraft would require prepared airfields which, in most cases, would not be available within the objective area. Gliders likewise required a clear and flat area in which to land and discharge troops. Assault by employing parachutists was discarded because of the difficulty in maintaining unit integrity. The use of troop and cargo carrying submarines appeared to offer a better solution than any of the airborne methods previously mentioned.
The Secretariat also considered the employment of the helicopter which, appearing to be superior in its characteristics to all other assault vehicles, offered a practical means of overcoming the effects of dispersion while concurrently reducing exposure of the amphibious task force. The Secretariat members knew that the performance of the helicopter was discouraging, but the relative primitive state of helicopter development did not deter their enthusiasm for its application.
The idea of using large assault transport seaplanes [TRSP] also received considerable attention by the Secretariat - a sort of "flying LST." But like the helicopter, a seaplane of the size needed for carrying troops and their equipment was not in existence. The Secretariat, nevertheless, concluded that a mixture of these large flying boats and helicopters would be the most promising combination, with the helicopter appearing to be the real "answer to the amphibious prayer."
In early December 1946, the study had progressed to the point where the principal recommendations could be foreseen and the Secretariat sent their report to the Special Board for approval. The Special Board submitted to the Commandant on 16 December 1946 an advanced report, recommending that "two parallel programs be initiated which would provide for the development of both the transport seaplane and a transport helicopter."
Commandan Vandegrift briefly defined the Marine Corps' plan for what later became known as the Vertical Assault Concept for Amphibious Operations and the premises upon which it was based. "Carrier-based transport helicopters. . . offer all the advantages of the conventional airborne operation but few of the disadvantages. They can be operated from aircraft carriers now in existence with cover and preparatory fires on landing areas provided by their aircraft from the same force... With a relatively unlimited choice of landing areas troops can be landed in combat formations and under full control of the flanks or rear of a hostile position. The helicopter's speed makes transport dispersion at sea a matter of no disadvantage and introduces a time-space factor that will avoid presenting at any one time a remunerative atomic target. It should be noted also that transport helicopters offer a means for rapid evacuation of casualties, for the movement of supplies directly from ship to dump and for subsequent movement of troops and supplies in continuing operations ashore."
The the Marine Corps School (MCS) "Helicopter Board' defined the Marines' assault helicopter as a vehicle capable of lifting 15 to 20 fully armed marines and, in 1948, prepared a plan for a Marine helicopter wing with 240 such aircraft capable of transporting a Marine regimental combat team in a single lift. The Marine Corps also established an experimental helicopter squadron, designated HMX-1, to develop helicopter assault doctrine in amphibious operations in parallel with the work of the MCS Helicopter Board. Unfortunately, no such machine as that envisaged by the Helicopter Board existed and HMX-1 at first had to make do with the HO3S-1 which could lift no more than two fully equipped Marines, in addition to its pilot.
MCS published its helicopter doctrine manual in November 1948 as Amphibious Operations-Employment of Helicopters (Tentative) or amphibious operations manual Phib-31. This remained the standard Marine doctrinal publication for the tactical use of helicopters throughout the Korean War. Phib-31 was to form the basis for the Marines' "vertical envelopment' concept, adopted in February 1951, by which initial Marine assaults are "all helicopter' affairs with the Marines landing to the rear and on the flanks of the enemy. The beach is then cleared from the rear and only when it is secured do reinforcements and supplies come in by boat "over the beach.'
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