The Largest Security-Cleared Career Network for Defense and Intelligence Jobs - JOIN NOW

Military


HCH [Model 86]

When the HRH was ended, the jet-tip rotor development continued on another design, the Model 86 or XHCH-1. This was to be a 35,000 lb ship-to-shore flying crane. McDonnell received a contract in 1952 for three prototypes, but the project was cancelled in January 1959.

The XHCH was designed to carry loads for very short distances as a flying crane with the capability of operating off aircraft carriers and being used for replenishment operations, lifting unflyable aircraft, and in general support of amphibious operations. Its payload was expected to be 15,000 pounds lifted over a distance of 20 miles, and in an "overload " condition, capable of carrying 25,000 pounds. Its demise, like that of the XHRH-1, eventually came as a result of insufficient funds to carry out development of the power plants, rotor head, and rotor blades.

During the developmental period of the XHRH-1, Commandant Cates had made repeated requests to CNO for the continuance of development funds as the helicopter appeared to offer the Marine Corps a greater assault lift capability than the HR2S. Nevertheless, the CNO had remained impervious to the Commandant's requests and pinned all hopes for success of a heavy helicopter on the XHCH.

The Navy-funded McDonnell's XHCH-1 failed primarily because the state of power plant and transmission development had not advanced sufficiently to match the demand. During 1956-1958, the US Army Transportation Research and Engineering Command (TRECOM) actively studied the technical aspects of flying crane helicopters. Research contracts to conduct design and cost analysis were let to leading aircraft manufacturers. TRECOM examined the flying crane concept and evaluated the conclusions reached by the several manufacturers.

One of the most significant conclusions was that the flying crane had singular requirements and design considerations which were not inherent in helicopters then in operation, and was very sensitive to changes in design, operating radius, and payload. For each payload and range combination there was an optimum power plant (shaft drive/tip-jet drive) and rotor (single, tandem, quad) combination.

Flying cranes were very large, very heavy aircraft. Rotor diameters on the order of 120 feet and empty weights in excess of 30,000 pounds were representative of flying cranes designed for payloads of 12 tons and operating radii of 50 nautical miles. A pure flying crane helicopter would have been of little value to the Marine Corps as there was only a limited opportunity for its useful employment in combat and, because of its size, it was difficult to load in amphibious shipping.

To satisfy the requirement To satisfy the requirement for heavy lifts without a true flying crane, it was envisioned that a heavy cargo helicopter could be stripped of its auxiliary power unit, communications/navigation equipment, and other removable equipment and operate with a reduced fuel load and minimum crew. It then could become a flying crane, of sorts, capable of lifting five or six tons of external cargo for a tactically significant distance.

Handicapped by not having a flying crane, the Marine Corps' course of action would be to continue to make up light loads, and sectionalize heavy items of equipment, and employ the future CH-53 8,000-pound payload helicopters in a limited flying crane role until technology could produce a smaller, more versatile, and efficient crane helicopter.



NEWSLETTER
Join the GlobalSecurity.org mailing list



 
Page last modified: 07-07-2011 02:32:55 ZULU