Bristol Theseus

The Theseus was the Bristol Aeroplane Company's first attempt at a gas-turbine engine design. A turboprop delivering just over 2,000 hp (1,500 kW) was chosen rather than compete with companies that were already developing turbojets. A heat exchanger to transfer waste heat from the exhaust to the compressor exit was necessary to meet a requirement for a fuel consumption comparable to a piston engine. The heat exchanger was abandoned after tests showed it had a high pressure loss and saved much less fuel than had been expected.[1]

Theseus
Preserved Bristol Theseus
Type Turboprop
Manufacturer Bristol Siddeley
First run 18 July 1945
Major applications Handley Page Hermes

As well as being one of the first engines to feature a free propeller turbine, the Theseus was the first turboprop in the world to pass a type test in January 1947.[2] Following 156 hours of ground runs and the receipt of a test certificate from the Ministry of Supply on 28 January 1947, two Theseus engines were fitted in the outer positions of a four-engined Avro Lincoln for air tests.[3] After ground and taxying test the Lincoln first flew on 17 February 1947.[3]

The engine was also installed in two Handley Page Hermes 5 development aircraft.[4]

It was soon superseded by the Proteus design with more power.

Applications

Bristol Theseus on public display

East Midlands Aeropark Castle Donington.

Variants
Theseus Series TH.11
Variant without heat exchanger
Theseus Series TH.21
Variant with heat exchanger
Theseus 502

Specifications (Theseus Th.21)

Data from Aircraft Engines of the world 1946[6]

General characteristics

  • Type: Mixed compressor turboprop with matrix heat exchanger
  • Length: 106 in (2.69 m)
  • Diameter: 48 in (1.22 m)[7]
  • Dry weight: 2,310 lb (1,050 kg)

Components

  • Compressor: 8-stage axial + 1-stage centrifugal compressors feeding the combustion chambers through a heat exchanger
  • Combustors: 8 x stainless steel can combustion chambers
  • Turbine: 2-stage axial + 1-stage axial free turbine driving the propeller
  • Fuel type: Kerosene (R.D.E. / F / KER)
  • Oil system: pressure feed to bearings, dry sump, 40 S.U. secs (13 cSt) (Intavia 620) grade oil

Performance

  • Maximum power output: 1,950 bhp (1,450 kW)@Sea Level Static, ISA plus 500 lbf (2.22 kN) residual thrust[7]
  • Overall pressure ratio: 5:1[8]
  • Air mass flow: 30.0 lb/s (13.61 kg/s)[8]
  • Specific fuel consumption: 0.57 lb/equiv. hp/h ( kg/equiv. kW/h)@ Max Power, 300mph, Sea Level, ISA[7]
  • Specific Fuel Consumption : 0.5 lb/equiv. hp/h ( kg/equiv. kW/h)@ Max Power, 300mph, 20000ft, ISA [7]
  • Thrust-to-weight ratio:
  • Maximum flight rating: 2,350 hp (1,750 kW) equivalent at Max Power, 300mph, Sea Level,ISA[7]
  • Maximum flight rating: 1,500 hp (1,100 kW) equivalent at Max Power, 300mph, 20,000 ft (6,100 m),ISA NOTE:Equivalent Power defined as Propeller Shaft Power plus (Jet Thrust * Flight Velocity/Propeller Efficiency) [7]

See also

References

Notes
  1. Turbojet History And Development 1930-1960 Volume 1, Antony Kay2007, ISBN 978 1 86126 912 6, p.139
  2. http://www.flightglobal.com/pdfarchive/view/1947/1947%20-%200602.html
  3. "Theseus Air Testing - First Bristol Airscrew Turbines Fly in a Lincoln : Some Features Discussed". Flight: 270. 27 March 1947.
  4. Gunston 1989, p.34.
  5. Test bed only
  6. Wilkinson, Paul H. (1946). Aircraft Engines of the world 1946. London: Sir Isaac Pitman & Sons. pp. 284–285.
  7. Practical Mechanics, February 1947, p.172
  8. Practical Mechanics, January 1947, p.116-118

Bibliography
  • Gunston, Bill. World Encyclopedia of Aero Engines. Cambridge, England. Patrick Stephens Limited, 1989. ISBN 1-85260-163-9
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