CONVAIR XB-46 Jet-Powered Medium Bomber Prototype
The CONVAIR XB-46 Medium Bomber was an American response to the arrival - and success - of the German wartime Arado Ar 234 Blitz jet-powered bomber.
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American authorities were not blind to the advances in military combat aircraft being made by the Germans during World War 2- particularly in their operational use of the Arado Ar 234 "Blitz" jet-powered bomber. The system, introduced during September of 1944, was fast enough to out-fly ground-based defenses as well as airborne interceptors and was used in both the traditional bomber role as well as fast reconnaissance. 210 of the type were produced before war's end but not nearly enough to make an impact on Germany's worsening fortunes during the conflict.
With that said, there was born an initiative on the part of the United States Army Air Forces (USAAF) to provide an all-modern, high-flying jet-powered medium bomber capable of reaching out to 1,000 miles and carrying a considerable war load. This prompted responses from the usual industry players of which Boeing, CONVAIR, Martin and North American proved the most notable. Respectively, the designs became XB-47, XB-46 (CONVAIR "Model 109"), XB-48, and XB-45 with only the XB-45 seeing serial production as the B-45 "Tornado" and XB-47 outshining them all as the production-minded B-47 "Stratojet".
In January of 1945, as World War 2 still raged in Europe and the Pacific, a mockup by CONVAIR was approved and a contract order for three prototypes followed in February. At the same time, the company was furthering another attack platform - the XA-44 (becoming the "XB-53" some time later) - and this played poorly into USAAF plans as its post-war defense budget was reeled in during the worldwide military drawdown that followed the surrender of Japan in August (1945). While the advanced, forward-swept-wing XA-44 was favored over the XB-46, both were allowed to continue along their respective development paths albeit through some revision of both product lines between CONVAIR and the USAAF: funding of two of the proposed XB-46 prototypes now became funding for two XA-44 prototypes. The USAAF ultimately rebranded in 1947 to become the United States Air Force (USAF).
The XB-46 held a conventional design arrangement as bombers of the period went. The nose section held the bombardier behind a plexiglass nosecone and the flight crew - pilot and copilot seated in tandem - were under a single-piece teardrop-style canopy with little framing used to provide excellent vision out-of-the-cockpit. The wing mainplanes were set at midships and were straight, high-mounted appendages each featuring an underslung engine nacelle. The fuselage was of an elegant design form and made extremely aerodynamically refined which served the speeds involved rather nicely. The empennage was capped by a single vertical tail fin and low-mounted horizontal planes. A tricycle undercarriage complete the look of this most modern bomber airplane.
Power was to come from 4 x Allison J35-A-3 turbojet engines developing 4,000lb of thrust each and in the assumed B-46 production forms, this was to be supplanted by 4 x General Electric J47 turbojets of 5,200lb thrust each for improved performance.
Internally, the aircraft was slated to carry a war load of up to 22,000lb in the way of conventional drop ordnance. There were also plans to introduce a twin-gunned "stinger" emplacement at the tail showcasing 2 x 0.50 caliber heavy machine guns through a powered Emerson Electric Company turret sporting an APG-27 remote-controlled sighting system.
As finalized, the XB-46 held a maximum speed of 545 miles per hour, a cruising speed near 440 miles per hour, a range out to 2,870 miles and a service ceiling up to 40,000 feet.
First flight for the XB-46 occurred on April 2nd, 1947 and initial results were largely positive though not without issue. Tests continued into September of that year with 64 flights being recorded though, in August, the USAF had terminated its interest in the CONVAIR product as the Boeing XB-47 had progressed to its expectations. The XA-44 / XB-53 product followed in cancellation, this during 1949, and the arrival of the B-47 also affected production totals of the competing XB-45 / B-45.
On the whole, the XB-46 proved a sound bomber design and only the sole flyable prototype XB-46 was ever completed. Its airframe was eventually scrapped over the years but it continued in testing various components under the USAF banner into late 1950.