The Secret Origins of America’s First Supersonic Bomber
The Convair B-58 was the first American bomber designed to fly supersonically for a significant portion of its mission. Its development was long and unconventional, rooted in concepts that were far ahead of the engineering capabilities of the time.
From Interceptor to Delta Wing Pioneer
Near the end of World War II, Consolidated Vultee began studying a ramjet-powered interceptor designated the XP-92. American engineers sifting through captured German aeronautical research discovered that swept and delta wings showed great promise for supersonic flight. The XP-92 was initially designed with swept wings, which were soon replaced by delta wings—offering superior high-speed performance and structural integrity without additional stabilizers.
Wind tunnel tested in 1946 and mocked up in early 1947, the XP-92 featured a fat cylindrical fuselage built around a single ramjet engine, 60-degree swept delta wings, and one large delta vertical stabilizer. However, rapidly improving turbojets rendered the ramjet-powered concept obsolete, and the program was terminated in August 1948.
A turbojet-powered derivative, the XF-92A, flew the following month and became the first true delta-winged manned aircraft to fly under its own power. Although capable of breaking the sound barrier only in a dive, it validated delta wing flight control at transonic speeds.
The Supersonic Bomber Concept
Parallel to the interceptor work, Consolidated Vultee launched the massive GEBO (Generalized Bomber) study in 1946, examining reportedly 10,000 strategic bomber configurations. One concept explored in depth involved a supersonic jet bomber carrying a large bomb/fuel pod, lifted by a B-36 for most of the journey—a practical workaround for the era’s chronic jet fuel limitations.
In 1948, now rebranded as Convair, the company proposed a two-component aircraft to both the US Air Force and Navy. The Navy variant responded to BuAer Outline Specification OS-115, which required cruise speeds of at least Mach 1.2, a cruising altitude above 40,000 ft, a mission radius of no less than 1,700 nautical miles, a maximum weight of 100,000 lb, and a 10,000 lb atomic bomb payload.
Two-Component Architecture
The system consisted of a manned bomber and an expendable pod. The manned component carried two crew, one afterburner-equipped turbojet, and 3,125 lb of fuel. Its fuselage had a roughly triangular cross-section with a nose inlet bifurcating around the tandem cockpit—clearly a relative of the XP-92, sharing similar wings and vertical tail geometry.
The expendable pod housed three turbojets in a triangular tail cluster, 5,208 lb of fuel, bomb-aiming radar, and the atomic weapon itself. After bomb release, the pod was simply jettisoned—it had no control surfaces or thrust vectoring, making any standoff weapon role impossible.
Navy vs. Air Force Variants
The Navy version launched directly from a carrier deck—specifically the planned CVA USS United States-class supercarrier—using jettisonable landing gear and RATO bottles. The Air Force version was carried under a B-36, allowing higher launch altitude and greater mission radius, and required no landing gear on the pod.
Once airborne, both variants performed identically. The composite aircraft cruised at Mach 1.3 using all four turbojets combined, with a maximum speed of Mach 1.6 before pod separation. After releasing the pod, the single-engined manned component returned at Mach 0.9 at 50,000 ft. The B-36 extended the total mission reach to approximately 4,000 miles from base.
No defensive armament was fitted — at Mach 1.5, the aircraft was considered immune to Soviet interceptors and surface-to-air missiles of the period.
Training Considerations
Landing with the pod attached was not feasible, which would have made routine training prohibitively expensive. Convair proposed a dedicated trainer variant replacing the pod’s radar, warhead, and most of its fuel with a retractable tricycle undercarriage, allowing composite landings while acknowledging that handling characteristics would differ significantly from the return-leg configuration alone.
This article is from the book “Secret Cold War Designs – US Supersonic Bomber Projects” by Scott Lowther, available here.
