Bell H-12

infobox Aircraft
name = R-12 (Model 48)
type = five/eight seat utility helicopter
manufacturer = Bell Helicopter



caption = YR-12B / YH-12B
designer =
first flight = 1946
introduced =
retired =
status =pre-series
primary user = United States Air Force
more users =
produced =
number built = 13
unit cost =
developed from = Bell 47
variants with their own articles = The Bell R-12 (Model 48) was an American 1940s military utility helicopter built by Bell Helicopter company.

Development

During 1946 Bell Helicopter began development of a new helicopter, much larger, that Model 47. It was partly basing upon its construction, first of all, a rotor system, and was basically a scaled-up version of Model 47. The basic variant was civilian Model 42, but the United States Air Force got interested in the design and ordered development of its military variant, Model 48. Two prototypes were ordered as the XR-12. It was powered by a 540 hp Pratt & Whitney R-1340-AN-1 radial engine and seated five. A production batch of 34 helicopters was ordered, under a designation R-12A, but it was cancelled afterwards. Another enlarged prototype (the XR-12B, Model 48A) with seats for eight and a more powerful 600 hp R-1340-55 engine was also ordered. It was followed by ten pre-series helicopters YR-12B, with a redesigned cabin, with a glazed nose, instead of car-like nose [ [http://www.aviastar.org/helicopters_eng/bell_48.php Bell Model 48] ] . With a change in designation system the helicopter was re-designated the H-12. Test were not satisfactory, there were initially problems with a main rotor, and none were ordered.

Variants

;XR-12:prototype, redesignated XH-12, two built.;R-12A:production version, 34 on order cancelled.;XR-12B:prototype with more powerful engine and increased seating, re-designated XH-12B, one built.;YR-12B:as XR-12B but with R-1340-55 engines, re-designated YH-12B, ten built.;XH-12:XR-12 re-designated in 1947.;XH-12B:XR-12B re-designated in 1947.;YH-12B:YR-12B re-designated in 1947.

Operators

;USA
*United States Air Force

pecifications (XR-12B)

aircraft specifications
plane or copter?=copter
jet or prop?=prop
crew=2
capacity=8
length main= ft
length alt= 12.06 m )(fuselage
span main= 47 ft 6 in
span alt= 14.48 m
height main= ft
height alt= 3.43 m
area main= 1,772 ft²
area alt= 164.62 m²
airfoil=
empty weight main=
empty weight alt=
loaded weight main= lb
loaded weight alt= 2854 kg
useful load main=
useful load alt=
max takeoff weight main= 6,286 lb
max takeoff weight alt= 2851 kg
engine (prop)=Pratt & Whitney R-1340-55 Wasp
type of prop=radial piston
number of props=1
power main= 600 hp
power alt= 447 kW

propeller or rotor?=rotor
propellers=1
number of propellers per engine=1
propeller diameter main=
propeller diameter alt=

max speed main= 105 mph
max speed alt= 169 km/h
cruise speed main= 90 mph
cruise speed alt= 145 km/h
never exceed speed main=
never exceed speed alt=
stall speed main=
stall speed alt=
range main= 300 miles
range alt= 483 km
ceiling main= ft
ceiling alt= 3960 m
climb rate main= ft/s
climb rate alt= 2.28 m/s
loading main=
loading alt=
more performance=
armament=

ee also

aircontent

related=
*Bell Model 47
*Bell Model 42
*Agusta-Bell AB.102
similar aircraft=
*Sikorsky H-19
lists=

see also=

References

* Andrade, John M. "U.S.Military Aircraft Designation and Serials since 1909". Leicester, UK: Midland Counties Publications, 1979. ISBN 0-904597-22-9.
* The Illustrated Encyclopedia of Aircraft (Part Work 1982-1985). London, Orbis Publishing.
* [http://www.aviastar.org/helicopters_eng/bell_48.php Bell Model 48] retrieved 2-6-2008

External links

* [http://www.aviastar.org/helicopters_eng/bell_48.php Bell Model 48] - description, photos and drawings