The Lockheed-Vega XB-38 was a prototype for an improved version of the Flying Fortress using inline liquid cooled engines to guard against any shortage of the standard R-1820s used on the B-17.
Vega had been involved in the B-17 production programme since 1941, completing its first B-17F-1-VE on 4 May 1942. Soon afterwards, on 10 July 1942, Vega was given a contract to produce an improved version of the B-17, using the 1,425hp Allison V-1710-89, an inline liquid cooled engine. To save time Vega used the Boeing-built B-17E they had been sent as a pattern aircraft for their own B-17 production as the prototype. The new engine was carried on the standard B-17 engine mounting, with the oil cooler placed below and behind the spinner and radiators in the leading edge of the wings between the nacelles.
In order to allow for fair tests, the remotely controlled Bendix turret originally installed on the aircraft was replaced with a dummy Sperry ventral turret. Other equipment was removed to make space for test instruments.
The XB-38 began a programme of flight trials on 19 May 1943. The first five flights went well, but after the sixth the aircraft had to be grounded for repairs. The ninth flight ended in disaster, when No.3 Engine caught fire. The two test crew, Bud Martin and George MacDonald baled out, but their parachutes failed to open properly and MacDonald was killed.
Despite this setback plans were put in place to produce a version of the XB-38 that combined the standard bombing role with the escort gunship role planned for the YB-40 Flying Fortress. However this plan was rejected by General Hap Arnold in August 1943, after the YB-40 concept was rejected. Instead Vega switched to production of the more powerful and better armed B-17G. The XB-38 was actually slower than the standard B-17F which it was meant to have replaced.
Engines: Four Allison V-1710-89, inline liquid cooled engine
Power: 1,425hp each
Wing span: 103ft 9in
Length: 74ft 9in
Height: 19ft 1in
Empty weight: 38,235lb
Loaded weight: 58,000lb
Maximum weight: 63,300lb
Maximum speed: 292mph at 25,000ft
Cruising speed: 192mph
Service ceiling: 25,100ft
Normal range: 2,260 miles
Maximum range: 2,480 miles
Lockheed Aircraft Since 1913, René J Francillon