Bell H-12 - Misplaced Pages

R-12/H-12
YH-12B
General information
Type	Military utility helicopter
Manufacturer	Bell Aircraft
Status	Pre-production
Primary user	United States Air Force
Number built	13
History
First flight	1946

The Bell R-12 (later redesignated H-12; company Model 48) was an American 1940s military utility helicopter built by the Bell Helicopter company. The design did not go into full production, but over a dozen prototypes were used for various tests and projects.

Design and development

During 1946, Bell Helicopter began development of a new utility helicopter, the Model 42, much larger than the Model 47, which utilized a scaled-up version of the Model 47's rotor system. Three prototypes were built, but serious rotor problems and complexity of mechanical systems precluded production. The initial Model 42 variant was civilian, but the United States Air Force ordered the development of its military variant, the Model 48. Two prototypes were ordered as the XR-12, powered by a single 540 hp (403 kW) Pratt & Whitney R-1340-AN-1 radial engine and featuring seating for five. Of very similar construction to the Model 42, the Model 48 had a shorter rotor mast. A production batch of 34 helicopters was ordered, under the designation R-12A, but cancelled in 1947.

Another enlarged prototype (the XR-12B, Model 48A) with seats for eight plus two pilots and a more powerful 600 hp (447 kW) Pratt & Whitney R-1340-55 engine was also ordered, followed by ten pre-series YR-12B helicopters, with a glazed nose, instead of the car-like nose of the Model 42 and XR-12. While under flight test the helicopter was redesignated the H-12, but the results were not satisfactory, as there were major problems with the main rotor due to blade weaving and poor rotor governor performance.

Operational history

Journalists and news reported examine a Model 12, which was used to survey the area after a nuclear test in Nevada. April 21, 1952.

No production H-12 aircraft were built but the prototypes and preproduction aircraft were used for various test and development programs.

It was unofficially known as the "Fat Boy".

Variants

Model 42: Bell's initial foray into the civilian luxury helicopter market, seating five. Three prototypes were built but serious problems precluded production.
Model 48: Company designation for the military version of the Model 42, given the designation R-12. Two built as XR-12s and a production contract for 34 was cancelled in 1947.
Model 48A: The more powerful derivative of the Model 48 with a 600 hp engine and ten seats. One XR-12B/XH-12B prototype was produced and a preproduction batch of ten were also built as YR-12B/YH-12Bs
XR-12: Prototype, redesignated XH-12, two built.
R-12A: Production version, 34 on order canceled.
XR-12B: Prototype with more powerful engine and increased seating, redesignated XH-12B, one built.
YR-12B: As XR-12B but with R-1340-55 engines, redesignated YH-12B, ten built.
XH-12: XR-12 redesignated in 1947.
XH-12B: XR-12B redesignated in 1947.
YH-12B: YR-12B redesignated in 1947.

Operators

United States

United States Air Force

Specifications (XR-12B)

Data from Bell Aircraft since 1935

General characteristics

Crew: one
Capacity: nine
Length: 56 ft 9 in (17.30 m)
Height: 11 ft 3.25 in (3.4354 m)
Gross weight: 6,286 lb (2,851 kg)
Powerplant: 1 × Pratt & Whitney R-1340-55 Wasp 9-cyl. air-cooled radial piston engine, 600 hp (450 kW)
Main rotor diameter: 47 ft 6 in (14.48 m)
Main rotor area: 1,772 sq ft (164.6 m)

Performance

Maximum speed: 105 mph (169 km/h, 91 kn)
Cruise speed: 90 mph (140 km/h, 78 kn)
Range: 300 mi (480 km, 260 nmi)
Service ceiling: 12,800 ft (3,900 m) Service ceiling
- Absolute ceiling: 15,000 ft (4,572 m)
- Hover ceiling: 4,350 ft (1,326 m)

References

Notes

^ Pelletier 1992, p. 92.
Pelletier 1992, p. 91.
Helicopter History and Aerodynamics. Randolph Air Force Base, Texas: Headquarters, Air Training Command, United States Air Force. 4 January 1961. p. 15. Retrieved 27 December 2024.
"Bell Model 48". aer.ita.br. Archived from the original on 24 December 2012. Retrieved 18 October 2014.

Bibliography

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, 1985.
Pelletier, A.J. Bell Aircraft since 1935. London: Putnam & Company Ltd., 1992. ISBN 1-55750-056-8.

External links

Copter Ferry Hops To The Front – Popular Science (December 1950)
The Unknown Helicopter – Vertical

v t e Bell Aircraft and Bell Helicopter/Bell Textron aircraft
Manufacturer designations	1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 (I) 39 (II) 40 41 42 43 44 45 46 47 J 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70–100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131–199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 214ST 215 216 217 218 219 220 221 222 223–229 230 231–248 249 250–300 301 302–308 309 310–359 360 361–399 400 401–405 406 407 408 409 410 411 412 413 414 415 416 417 418–426 427 428 429 430 431–439 440 441 442 443 444 445 446 447 448 449 550–504 505 506–524 525 526–532 533 534–539 540 541–547 548 549–575 576 577–582 583 846–598 599 600–608 609 610–645 646 647–679 680 681–910 911 912–917 918 D-188 D-255 D-292
Fighter aircraft	YFM-1 P-39 XFL P-59 P-63 P-76 XP-77 XP-83
Target drones	PQM-56
Attack helicopters	207 Bell AH-1 Singles Twins AH-1Z 309 YAH-63 360
Observation and utility helicopters	H-13 H-13J UH-1 UH-1N UH-1Y TH-57 OH-58 TH-67 ARH-70
Commercial helicopters	47 47J 204 205 206 210 212 214 214ST 222 230 407 412 427 429 430 505 525
Tiltrotors	V-22 V-247 V-280 AW609 TR918 QTR
UAVs	MQ-8C
Non-production helicopters	400 417 440
Experimental aircraft	ATV 201 533 D-188 D-255 D-292 FCX-001 L-39 LLRV/LLTV X-1 X-2 X-5 X-14 X-16 X-22 XF-109 XP-52 XV-3 XV-15
Names	Airabonita Airacobra Airacomet Airacuda Arapaho BigLifter Cobra Creek Eagle Eye Fire Scout GlobalRanger Huey HueyCobra Invictus Iroquois JetRanger Jet Ranger X Kingcobra KingCobra Kiowa LongRanger Osprey Quad TiltRotor Ranger Sea Cobra Sea Ranger Sioux Sioux Scout SuperCobra Super Huey Super Transporter Twin Huey TwinRanger Valor Venom Vigilant Viper Zulu Cobra
Unknown/not assigned

United States helicopter designations, Army/Air Force and Tri-Service systems

Numerical sequence used by USAAC/USAAF/USAF 1941–present; U.S. Army 1948–1956 and 1962–present; U.S. Navy 1962–present

Army/Air Force sequence
(1941–1962)

Prefix R-, 1941–1948	R-1 R-2 R-3 R-4 R-5 R-6 R-7 R-8 R-9 R-10 R-11 R-12 R-13 R-14 R-15 R-16
Prefix H-, 1948–1962	H-5 H-6 H-9 H-10 H-11 H-12 H-13 H-13J H-15 H-16 H-17 H-18 H-19 H-20 H-21 H-22 H-23 H-24 H-25 H-26 H-27 H-28 H-29 H-30 H-31 H-32 H-33 H-34 H-35 H-36 H-37 H-38 H-39 H-40 H-41 H-42 H-43 H-44 H-45

Tri-Service sequence
(1962–present)

1962 redesignations	H-13 H-13F H-13J H-19 H-21 H-23 H-25 H-34 H-37 H-43
New designations	H-46 H-47 H-48 H-49 H-50 H-51 H-52 H-53 CH-53/E/K HH-53/MH-53 H-54 H-55 H-56 H-57 H-58 H-59 H-60 UH-60 SH-60 HH-60 MH-60 H-61 H-62 H-63 H-64 H-65 H-66 H-67 H-68 H-69 H-70 H-71 H-72 H-73
Alternate sequence	H-1 AH-1/J/T/W/Z UH-1/N/Y H-2 G H-3 CH-3/HH-3 SH-3 H-4 H-5 H-6 AH-6 MH-6 OH-6
Non-sequential	H-90 H-92 CH-92/VH-92 H-139

Not assigned

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