Little-known Northrop flying wings of 1940s-early 1950s, part 3: commercial and military transport designs

For over four decades, US aerospace companies like Boeing, Lockheed Martin, and Northrop Grumman (in concert with NASA) have tinkered with the notion of blended wing body (BWB) aircraft that could be used as airliners, air freighters, or airlifters, recognizing that a BWB design could offer greater carrying capacity and better fuel efficiency than conventional American long-range airliners like the Boeing 747, 777, and 787. However, the notion of adapting a flying wing or blended wing body design for use as a commercial airliner, cargo carrier, or airlifter is not a recent phenomenon; in the late 1940s and early 1950s, the Northrop Corporation investigated the possibility of using flying wings to carry passengers and cargo, producing the first designs for commercial flying wings.

*McDonnell Douglas (absorbed by Boeing in August 1997) tinkered with studies for flying wing/BWB designs that could carry hundreds of passengers or freight loads beginning in the late 1970s. Boeing took stewardship of design studies into passenger and commercial freight BWB aircraft that McDonnell Douglas had conceived beginning in 1988 after acquiring McDD in 1997, so I've omitted mention of McDonnell Douglas in the first paragraph of the post for convenience.

Rising Cold War tensions and the aftershocks of the Berlin Airlift prompted the United States Air Force to stress the importance of strategic heavy airlift in overseas US military operations, considering that World War II had seen American troops ferried to Europe and the Pacific via troopship. The Douglas C-74 Globemaster I and Boeing C-97 Stratofreighter designed in the WW2 era came too late for the war, but the USAF learned the hard way when dealing with the question of hauling large loads of troops and military equipment to faraway war zones in a short space of time. Meanwhile, mass air freight was very much in its infancy, with air freight being carried out largely by mail planes, and the technology of the jet airliner had just come into being with the first flight of the de Havilland D.H.106 Comet in 1949. Perhaps sensing the growing importance of heavy airlift in the post-WW2 era and the vastly enhanced carrying capacity offered by a flying wing/BWB design, Northrop decided to look into adapting its flying wing designs for use as airliners, air freighters, and airlifters.

Left: Cutaway view of the interior of the airliner version of the Northrop YB-49 flying wing jet bomber
Right: Interior of the mock-up of the airliner version of the YB-49

Beginning in the late 1940s, Jack Northrop investigated adapting the YB-49 flying wing jet bomber for use as a jet airliner. His company hired a Hollywood film studio to make a film touting the benefits of a jet airliner based on the YB-49, including the creation of a full-size mockup complete with rolling food carts and beautifully dressed actors posing as passengers. The airliner version of the B-49 would have had accommodated 50-80 passengers. However, the proposed flying wing airliner wasn't taken seriously by the airline industry in light of longitudinal instability experienced by the YB-49 during flight testing, so it never went beyond the drawing board. If Northrop had managed to get its airliner derivative of the B-49 into the hardware phase, it would have been the first US jetliner rather than Boeing 707, considering that the YB-49 derived flying wing airliner was envisaged around the time that Boeing proposed America's first design for a jetliner, the Model 473.

Left: Northrop cargo pod-carrying flying wing transport design study, 1949
Right: Three-drawing of a Northrop flying wing transport with four Allison T40 turboprops, April 1950

As I mentioned in the post about the EB-35B, Northrop had conceived a transport version of the XB-35 under the N-10 designation, but that project never came to fruition. However, by 1949, thanks to the Berlin airlift having highlighted the importance of strategic heavy airlift, Northrop returned to adapting the N-9 series for used as strategic airlifters, this time proposing a spree of flying wing airlifter designs powered by turboprop engines. One Northrop flying wing airlifter design dated April 27, 1949 had the same wingspan and outer wing panels as the B-35 and B-49 but was powered by two Allison T40 turboprops and had a raised center section housing a 75-foot long cargo pod that could accommodate either 84 combat troops or a bombardment crew and nuclear weapons (drawings in Chong, p. 69, and Cox & Kaston, p. 174). An alternative airlifter design, powered by two Northrop XT37 turboprops, retained the flat wing profile and wingspan of the N-9 development lineage and was to carry two cargo pods outboard of the T37 turboprops. Northrop's designs for cargo flying wings for the commercial market were basically based on the N-31 medium bomber design in terms of a forward fuselage section protruding from the wing and came in two iterations, one powered by four Allison T40s and another with two T37s. The Northrop commercial flying wing freighters dispensed with the external pods for cargo carriage and instead relied on hauling transit vans and they both had a cruising speed of 380-400 mph (612-644 km/h) as well as a higher aspect ratio wing to deliver greater fuel economy and range (Cox and Kaston, pp. 175-176). The T40-powered flying wing freighter was 102 feet 9 inches (31.32 meters) long with a wingspan of 184 feet 2 inches (56.11 meters), a wing area of 5,018 square feet (466.68 sq. meters), and a payload of 70,000 pounds (31,751.5 kg). The Turbodyne-powered proposal would have had the same wingspan as the B-35 and B-49 but with a slightly longer fuselage measuring 80 feet 2 inches (24.43 meters) in length, and it was to carry a payload of 66,000 pounds (29,940 kg).

Despite a marketing blitz by the Northrop Corporation trumpeting the advantages of its commercial and military cargo flying wing designs, unsurprisingly, neither the US Air Force nor the civil aviation industry had any genuine interest in these flying wing projects. And if minimal customer interest weren't enough, the Allison T40 turboprop that would have powered the four-engine Northrop flying wing transport proposals was beset by teething troubles and proved to be a complete engineering failure when it came to usage on several aircraft it powered, including the Convair P5Y and R3Y Tradewind flying boats, Douglas A2D Skyshark attack aircraft, Republic XF-84H Thunderscreech, and North American XA2J Super Savage prototype carrier-based strategic bomber. Nevertheless, the design philosophy embodied by Northrop commercial flying wing freighter designs of 1949-1950 lives on in the many designs for flying wing and blended wing body designs that have been worked on (and continue to be investigated) since the late 1970s by Boeing, Lockheed Martin, McDonnell Douglas, and Northrop Grumman.

References:

Chong, T., 2016. Flying Wings & Radical Things: Northrop's Secret Aerospace Projects & Concepts 1939-1994. Forest Lake, MN: Specialty Press. 

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