Engineering:General Electric J87
The General Electric J87 was a nuclear-powered turbojet engine designed to power the proposed WS-125 long-range bomber. The program was started in 1955 in conjunction with Convair for a joint engine/airframe proposal for the WS-125. It was one of two nuclear-powered gas turbine projects undertaken by GE, the other one being the X39 project.[1]
Design and development
The J87 was a large turbojet, designed to operate as a paired unit, with a nuclear reactor power section. The complete power-plant was given the project designation X211.[1]
The X211 was a relatively large multiple turbojet engine of conventional layout, save for the combustion chambers being replaced by a nuclear reactor where half of the total air-flow through the turbojet sections was used for direct-cycle cooling of the reactor. The J87 components featured variable-stator compressors and chemically fuelled afterburners and a single nuclear reactor to supply heat to both J87 engines.[1][2]
Several arrangements for the X211 were studied but eventually the paired J87 was chosen and development was started at General Electrics Evendale factory. The air by-passed around the XMA-1A nuclear reactor passed through can-style combustion chambers arranged around the core, used for starting, burning normal jet fuel to ensure cooling air flow for the reactor as soon as it was started-up. The reactor core sat in the middle of the combustion section, fed with cooling air from a large plenum chamber. Heated exhaust air was collected by another plenum chamber to be fed to the turbine sections. Testing of the X211 was confined to the XJ87 turbojet sections.[1]
In 1956, the United States Air Force (USAF) decided that the proposed WS-125 bomber was infeasible as an operational strategic aircraft. In spite of this, the X211 program was continued for another 3 years, albeit with no target application. It was finally terminated in mid-1959 and by 1961, all funding for nuclear propulsion was removed.[1]
The competing Pratt & Whitney indirect-cycle engines used J91 turbojet sections in the X287 and X291 projects, which were also cancelled with the demise of the nuclear-powered bomber program.[1]
Specifications (single J87)
General characteristics
- Type: Afterburning direct-cycle nuclear turbojet
- Length: 41 ft (12 m)
- Diameter: 80 in (2,000 mm) +
- Dry weight: 15,745 lb (7,142 kg) turbojet section sans reactor
Components
- Compressor: 16-stage variable stator axial compressor
- Combustors: Direct-cycle air-cooled XMA-1A nuclear reactor
- Turbine: 3-stage axial turbine
- Fuel type: Nuclear (JP-4 to start)
Performance
- Maximum thrust: 27,370 lbf (121.7 kN) 34,600 lbf (154 kN) with afterburner
- Overall pressure ratio: 14:1
- Bypass ratio: 50% by-passed reactor
- Air mass flow: 425 lb/s (193 kg/s)
- Turbine inlet temperature: ca 1,800 °F (980 °C; 1,260 K)
- Power-to-weight ratio:
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Carpenter, David M. (2003). NX-2. United States: Jet Pioneers of America. ISBN 9780963338792. http://leehite.org/anp/documents/NX-2_ANP_1951-1961_Convair_Nuclear_Propulsion_Jet.pdf. Retrieved 10 November 2014.
- ↑ "Nuclear Powered Aircraft History + Smallest Nuke Power Plants". https://xenophilius.wordpress.com/2009/07/23/nuclear-powered-aircraft-history/.
- ↑ Gunston, Bill (2006). The development of jet and turbine aero engines (4. ed.). Sparkford: PSL. p. 156. ISBN 0750944773.
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