General Electric J87
| J87 | |
|---|---|
| |
| Cutaway drawing of the WS-125 testbed aircraft, showing its two J87 engines. | |
| Type | Nuclear powered afterburning turbojet |
| National origin | United States |
| Manufacturer | General Electric |
| Number built | at least 2 |
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
[edit]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)
[edit]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)
References
[edit]- ^ a b c d e f g Carpenter, David M. (2003). NX-2 (PDF). United States: Jet Pioneers of America. ISBN 9780963338792. Archived from the original (PDF) on 10 November 2014. Retrieved 10 November 2014.
- ^ "Nuclear Powered Aircraft History + Smallest Nuke Power Plants". xenophilius.wordpress.com. Archived from the original on 21 December 2014. Retrieved 10 November 2014.
- ^ Gunston, Bill (2006). The development of jet and turbine aero engines (4. ed.). Sparkford: PSL. p. 156. ISBN 0750944773.