XB-35

XB-35
Name	Northrop XB-35
Role	Experimental flying wing bomber prototype
Manufacturer	Northrop Corporation
First flight	1946
Status	Prototype; program canceled
Primary user	United States Army Air Forces
Number built	4 (two XB-35, two YB-35 partial conversions)

XB-35 The XB-35 was an experimental flying wing heavy bomber prototype developed by the Northrop Corporation for the United States Army Air Forces during and after World War II. Designed to exploit low-drag aerodynamics, the XB-35 program involved pioneering work in tailless aerodynamics, turboprop propulsion plans, and large-scale structural innovation but was ultimately superseded by conventional designs and the jet age. The program intersected with major figures and institutions such as Jack Northrop, the Wright Field test community, and the postwar transition to the United States Air Force.

Design and development

Northrop initiated the XB-35 project under contract with the United States Army Air Forces in 1941 as a response to specifications that also produced designs like the Boeing B-29 Superfortress and the Consolidated B-32 Dominator. Led by designer Jack Northrop, the company explored concepts previously studied in the Northrop Gamma and earlier tailless experiments that traced lineage to the interwar Heinkel and Horten work. The XB-35 design sought to integrate the powerplants, fuel storage, and bomb bays within a thick, cantilevered wing skin, echoing research at Langley Research Center and practical developments at Wright-Patterson Air Force Base. Contract modifications after V-E Day shifted priorities as contemporary projects such as the Boeing B-47 Stratojet and emerging jet propulsion programs altered funding and strategic emphasis.

Technical description

The XB-35 employed a large, low-aspect-ratio flying wing planform with a crew compartment embedded in the wing and four pratt & whitney-driven counter-rotating pusher propellers in buried engine nacelles. Structural concepts included shear-web spars and integral fuel tanks influenced by work at Douglas Aircraft Company and Lockheed laboratories. Flight control used split drag rudders and elevons, concepts similar to those later refined on research platforms at NASA. Its intended systems suite included navigation and bombing equipment analogous to installations on the Boeing B-29 Superfortress and radio systems compatible with Mitchell-era avionics suppliers. Aerodynamic features overlapped with contemporary tailless studies from de Havilland and stability research at Caltech and Massachusetts Institute of Technology.

Operational history

Prototypes were constructed and flown under the oversight of United States Army Air Forces testing organizations based at Wright Field and later evaluated by personnel from the newly created United States Air Force. The XB-35 program encountered delays due to wartime resource shifts and engine development problems linked to producers like Allison Engine Company and General Electric. Early flights occurred in the late 1940s and coincided with advances in rival programs such as the Convair B-36 Peacemaker and Boeing B-50 Superfortress, which shaped procurement decisions. Political and industrial dynamics involving Congress appropriations, Secretary of War oversight, and competition with firms like Convair influenced the program's operational trajectory.

Evaluation and testing

Flight testing at Wright Field and follow-on assessments by test pilots with ties to Lockheed and McDonnell revealed handling challenges, vibration and gearbox issues, and complications with propeller reverse torque effects similar to problems experienced on early turboprop projects. Test engineers referenced wind-tunnel data from NASA Langley Research Center and structural fatigue investigations comparable to studies at Bell Aircraft Corporation. The program produced valuable flight-test data on stability, control integration, and low-speed handling that paralleled experimental work on the North American X-15 and maintenance practices later codified by the Federal Aviation Administration.

Variants and proposed derivatives

Several derivative concepts and conversions were proposed, including a jet-powered flying wing that would have paralleled development paths pursued by Boeing and Convair for strategic bombers such as the Boeing B-52 Stratofortress. Planned variants included YB-35 service-test conversions and projected improvements incorporating turboprop and early turbojet installations akin to engines from Pratt & Whitney and Rolls-Royce. Competing proposals by other manufacturers for large strategic platforms, including studies at Douglas Aircraft Company and Martin Company, influenced the cancellation of many planned XB-35 derivatives. Later, some concepts were revisited in classified studies funded through Air Force Systems Command and in think-tank reports circulated among institutions like RAND Corporation.

Legacy and influence on later aircraft

Although the XB-35 never entered production, its innovations influenced later tailless and stealth concepts developed by organizations such as Northrop Grumman and research at NASA Ames Research Center. The program's integration of payload, propulsion, and structure presaged the blended-wing-body studies that informed designs like the B-2 Spirit and experimental work by Boeing and Lockheed Martin. Flight-test data from the XB-35 supported aerodynamic modeling used by researchers at Massachusetts Institute of Technology and Caltech and informed structural approaches adopted on later large transports including the Lockheed C-5 Galaxy. The XB-35 remains a milestone in the lineage connecting interwar tailless pioneers such as Heinkel and Horten to modern stealth and blended-wing developments championed by companies like Northrop Grumman and research centers such as NASA.

Category:Experimental aircraft