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Boeing XB-38 Flying Fortress

United States (1943)

Detailing the development and operational history of the Boeing XB-38 Flying Fortress Strategic Heavy Bomber Aircraft Prototype.

 Entry last updated on 2/10/2017; Authored by Staff Writer; Content ©

  Boeing XB-38 Flying Fortress  
Picture of Boeing XB-38 Flying Fortress Strategic Heavy Bomber Aircraft Prototype

The Boeing XB-38 was a study involving the classic B-17 Flying Fortress heavy bomber arranged with liquid-cooled inline piston engines - only one example was completed and lost during testing.

The success and availability of the Boeing B-17 "Flying Fortress" heavy bomber in World War 2 (1939-1945) meant that there were many related projects centered on getting more out of this Boeing product. The XB-38 was a short-lived program by the company to test the feasibility of replacing the original B-17's air-cooled radial piston engines with Allison inline piston types. A B-17 airframe was pulled from the existing stock and modified in this way and the prototype served in several flights before several major issues ended the program in full.

The engine of choice became the Allison V-1710-97 turbosupercharged V12 liquid-cooled inline piston engine of 1,425 horsepower. These were set across four individual nacelles with two engines per wing (as in the original B-17 arrangement). One major, physical difference in the installations was in their streamlined appearance as air-cooling was no longer necessary in the liquid-cooled powerplants. This gave the B-17 a unique look as the three-bladed propellers now sat on large, conical spinners. Beyond this physical change, the bomber retained much of its original form (and function).

In testing, the aircraft was able to make 327 mph and cruise at 226 mph. Range was out to 3,300 miles and service ceiling reached 29,600 feet. The aircraft was made faster than previous iterations of the B-17. However, the trade-off was in a lower service ceiling which was a poor quality for a strategic bomber to have. In comparison, the popular B-17G production model reached a maximum speed of 287 mph and cruised at 182 mph but the service ceiling was substantially higher at 35,600 feet.

Two key issues served to end the XB-38 program: Firstly the V-1710 engine being a standard fit on several other important fighter products of the war including the Lockheed P-38 "Lightning" and the North American "P-51" Mustang (A-models). As such, the availability of these powerplants would be in question should the XB-38 have entered serial production for there was already much demand for the engines elsewhere. Secondly the sole prototype was lost during the ninth flight of its test phase. On June 16th, 1943, one of the engines caught fire resulting in a bailout by the crew and the aircraft crashing. With nothing to show for the efforts, the XB-38 was written off and the project cancelled.
Any available statistics for the Boeing XB-38 Flying Fortress Strategic Heavy Bomber Aircraft Prototype are showcased in the areas immediately below. Categories include basic specifications covering country-of-origin, operational status, manufacture(s) and total quantitative production. Other qualities showcased are related to structural values (namely dimensions), installed power and standard day performance figures, installed or proposed armament and mission equipment (if any), global users (from A-to-Z) and series model variants (if any).
Boeing XB-38 Flying Fortress Specifications
National Flag Graphic
United States
Year: 1943
Type: Strategic Heavy Bomber Aircraft Prototype
Manufacturer(s): Boeing Company - USA
Production: 1
Supported Mission Types
Ground Attack
Close-Air Support
Airborne Early Warning
Electronic Warfare
Aerial Tanker
Passenger Industry
VIP Travel
Business Travel
Special Forces
Crew: 10
Length: 73.98 ft (22.55 m)
Width: 103.84 ft (31.65 m)
Height: 19.19 ft (5.85 m)
Empty Weight: 34,745 lb (15,760 kg)
MTOW: 64,000 lb (29,030 kg)

Installed Power
4 x Allison V-1710-97 turbosupercharged V12 liquid-cooled inline piston engines developing 1,425 horsepower each.

Standard Day Performance
Maximum Speed: 326 mph (525 kph; 283 kts)
Maximum Range: 3,299 mi (5,310 km; 2,867 nm)
Service Ceiling: 29,593 ft (9,020 m; 5.60 mi)

10 x 0.50 caliber Browning heavy machine guns along various positions of the aircraft including a dorsal turret, belly turret, tail emplacement, and nose and beam positions.

Internal bomb load of 6,000lb.

Operators List
United States (cancelled)

Series Model Variants
• XB-38 - Base Series Designation; one example completed.

Supported Weapon Systems
Graphical image of an aircraft medium machine gun
Graphical image of an aircraft heavy machine gun
Graphical image of an aircraft conventional drop bomb munition