Unseen 1940s airplane designs of Hughes Aircraft, part 2: the Models 31 and 32 assault gliders

Despite the end of World War II, transport gliders remained an integral part of the US Army's planning, as evidenced by the fact that the Army wished to have future transport gliders designed for long-range flights with a towing speed of 200 mph (322 km/h) and to be capable of being stored and maintained, the latter which required that a transport glider be built using a metal monocoque airframe or welded tubing with a metal covering rather than wood and fabric in construction. With this in mind, the Air Service Technical Command of the US Army Air Force on January 11, 1946 announced a competition for two new all-metal assault gliders capable of being towed by powered transports at 200 mph (322 km/h), a 'light glider' able to carry an 8,000 lb (3,632 kg) payload and a 'heavy glider' capable of carrying a 16,000 lb (7,264 kg) payload. 

Three view-drawings of the Hughes Model 31 light transport glider (left) and Model 32 heavy transport glider (right) from the project documents (courtesy of National Archives)

To satisfy official USAAF requirements for an all-metal transport glider, in the early spring of 1946, the Hughes Aircraft Company envisaged a light assault glider design with the company designation, Model 31, and it later proposed a heavy assault glider under the designation Model 32. The two designs were to be divided into three modules, with the forward section (including the cockpit) to be made out of phenolic-infused glass fiber panels, and the center and aft fuselage sections would utilize aluminum monocoque construction. The Model 31 had a clear-view nose comprising Plexiglas panels, and a hinged, upward-swinging rear fuselage to facilitate easier access to the cargo compartment, while the Model 32 had a solid nose section and would use a full-width ramp on the lower surface of the upswept rear fuselage for loading war material into the cargo bay. The Model 31 was 72 feet 5 in (22.09 meters) long with a wingspan of 73 feet 6 in (22.42 meters), a height of 26 feet 6 in (8.08 meters) (40 feet 2 in (12.25 meters) with tail raised), a wing area of 900 ft² (83.61 m²), and a gross weight of 15,500lb (7,037 kg). By contrast, the Model 32 was to have a length of 87 feet 3 in (26.61 meters), a wingspan of 90 feet (27.45 meters), a height of 33 feet 1 in (10.09 meters), a wing area of 1,360 ft² (126 m²), and a gross weight of 28,190 lb (12,798 kg). The Model 31 accommodated up to 30 troops or 24 stretchers and the Model 32 would have been capable of accommodating nearly twice as many troops as the Model 31.

By mid-April 1946, the Hughes Model 31 along with the Bell D-44 and Douglas Model 1028 proposals were submitted to the USAAF's light assault glider competition (the Chase MS-7 light transport glider design that became the XCG-18 had been envisaged shortly before the ASTC requirements and thus was excluded from the light assault glider competition). The Model 31 was judged by the Army Air Force to have very deficient minimum stall speed, a poor cockpit arrangement, inadequate space for cargo storage, and a small number of troops and litters possible of loading compared to the Douglas Model 1028, and on June 14, 1946, the USAAF declared the Douglas design the winner of the light assault glider competition, and designated it XCG-19. Of course, the XCG-19 only got as far as the mock-up phase and the XCG-18 prototype was nearing completion when the Army Air Force canceled the XCG-19 program in March 1947 due to a tight budget, but that's another story. The Hughes Model 32, for its part, was submitted for evaluation by the Army Air Force in June 1946 along with the rival Bell D-45, Chase MS-3, and Douglas Model 1029 designs, and on July 8 the Model 32 along with the Bell and Douglas submissions lost the heavy assault glider competition to the Chase MS-3, which was eventually designated XCG-20. Having lost the light and heavy assault glider competitions, Hughes left to focus on both the XF-11 and H-4 programs before abandoning fixed-wing aircraft development after 1947, when it turned its attention to helicopters, electronic systems, and guided missiles.

References:

Cox, G., and Kaston, C., 2019. American Secret Projects 2: U.S. Airlifters 1941 to 1961. Manchester, UK: Crécy Publishing.

Norton, W. J., 2012. American Military Gliders of World War II: Development, Training, Experimentation, and Tactics of All Aircraft Types. Atglen, PA: Schiffer Publishing.