Northrop YB-35
The Northrop YB-35 was a flying-wing heavy bomber developed for the U.S. Army Air Forces from a 1941 requirement for a bomber able to reach Germany from North America. First flown in June 1946, it carried its crew, fuel and bombs inside one wing of 172 ft span, powered by four piston engines driving pusher propellers. Gearbox and propeller problems kept test flying to a minimum, the production contract was cancelled, and the Air Force ended the programme in 1950 after converting several airframes to the jet-powered YB-49. Every example was scrapped and none survives.
Why It Mattered
Jack Northrop believed that an aircraft built as a single wing, with no fuselage or tail, would be more efficient than conventional tailed aircraft. His small N-1M test wing first flew on July 3, 1940, and showed that the all-wing idea could be controlled in the air. In 1941 the U.S. Army, fearing it might have to fight a transatlantic war, wanted a super-bomber that could carry 10,000 pounds of bombs to Germany from North America. The B-35 was Northrop's answer: the flying-wing idea built at full size as a prototype heavy bomber.
Design Notes
The YB-35 carried everything inside a single thick wing of 172 ft span, with no separate fuselage or tail section. Four Pratt & Whitney R-4360 reciprocating engines, buried within the wing, drove pusher propellers at the trailing edge. Control without a tail had been worked out on the small test wings, where elevons in the trailing edge gave the pilot pitch and roll control. Four larger N-9M models were built and flight tested to explore the big wing's stability and handling before it flew.
Operational History
The first XB-35 flew on 25 June 1946, from Northrop's Hawthorne field to Muroc Lake in California. Gearbox and propeller-control trouble grounded the aircraft in September 1946, after only three test flights totalling just over three hours. Testing never escaped the propulsion problems: the engines overheated and the propeller shafts vibrated, and the two XB-35s managed only 36 hours of flying in all. The production contract was cancelled, leaving only two experimental XB-35s and thirteen service-test YB-35s on order. The first YB-35 did not fly until 15 May 1948, and only the first YB-35 is reported ever to have flown. Most of the remaining airframes went instead to jet conversion as YB-49s, the wing's second life, and the Air Force ended the all-wing program in May 1950.
Afterlife
The YB-35 never entered service, and none was kept: the Air Force reported that all of the XB-35s and the YB-49s were scrapped by 1953. Under agreements reached in 1949, the two XB-35s and the first two YB-35s were marked for scrapping, while other airframes fed the jet conversion programme. The last full-scale wing, a YB-35A converted to the jet reconnaissance YRB-49A, was authorized for reclamation in November 1953. No complete YB-35 survives; the type is known now only from reports and photographs.