XB-39 Superfortress

Infobox Aircraft
name = Boeing XB-39 Superfortress


caption =
type = Test-bed bomber aircraft
manufacturer = Boeing
designer =
first flight = 1944
introduced = n/a
retired =
status = Never mass-produced
primary user = United States Army Air Forces
more users =
produced = 1944
number built = 1
unit cost =
variants with their own articles = The Boeing XB-39 Superfortress was a United States prototype bomber aircraft, a single example of the B-29 Superfortress converted to fly with alternative powerplants. It was intended to demonstrate that the B-29 could still be put into service even if the first choice of engine, the air-cooled Wright R-3350 radial engine, ran into development or production difficulties.

Starting life as the first YB-29 delivered to the United States Army Air Forces, it was modified by the US manufacturing company General Motors to use Allison V-3420-17 liquid-cooled twin-V12 inline engines. Testing on it began in early 1944. Since no very serious problems with the R-3350 developed, and most flaws of the B-29 were worked out by the time production began, the B-39 was not ordered into production.

pecifications (XB-39)

aircraft specifications

plane or copter?=plane
jet or prop?=prop

crew=10: pilot, co-pilot, flight engineer, bombardier, navigator, radio operator, side gunners (two), top gunner, and tail gunner
length main=99 ft 0 in
length alt=30.18 m
span main=141 ft 3 in
span alt=43.05 m
height main=27 ft 9 in
height alt=8.46 m
area main=1736 ft²
area alt=161.3 m²
empty weight main=74,500 lb
empty weight alt=33,800 kg
loaded weight main=120,000 lb
loaded weight alt=54,000 kg
max takeoff weight main=133,500 lb
max takeoff weight alt=60,560 kg

engine (prop)=Allison V-3420-11
type of prop=liquid-cooled V24 engines
number of props=4
power main=2,100 hp
power alt=1,600 kW

max speed main=405 mph
max speed alt=351 knots, 648 km/h
range main=6,290 mi
range alt=5,460 nm, 10,060 km
ceiling main=35,000 ft
ceiling alt=11,000 m
climb rate main=
climb rate alt=
loading main=69.12 lb/ft²
loading alt=337.5 kg/m²
power/mass main=0.073 hp/lb
power/mass alt=121 W/kg

guns=
** 8× .50 in (12.7 mm) Browning M2 machine guns in remote controlled turrets
** 2× .50 in (12.7 mm) machine guns in manual turrets
** 1× 20 mm (0.787 in) M2 cannon in tail
bombs=20,000 lb (9,000 kg)

ee also

aircontent
related=
* B-29 Superfortress
* XB-44 Superfortress
* B-50 Superfortress

sequence=

lists=
* List of bomber aircraft
* List of military aircraft of the United States

see also=

References

Notes

Bibliography

* Jones, Lloyd S. "U.S. Bombers, B-1 1928 to B-1 1980s". Fallbrook, CA: Aero Publishers, 1962, second edition 1974. ISBN 0-8168-9126-5.

External links

* [http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=2588 XB-39 on USAF Museum site]