Rolls-Royce Soar

Soar
Rolls-Royce Soar on display at the Rolls-Royce Heritage Trust, Derby
Type	Turbojet
Manufacturer	Rolls-Royce Limited
First run	January 1953
Developed into	Rolls-Royce RB108

The Rolls-Royce RB.93 Soar, also given the Ministry of Supply designation RSr., was a small, expendable British axial-flow turbojet intended for the UB.109T cruise missile use and built by Rolls-Royce Limited in the 1950s and 1960s. Like all the company's gas turbine engines it was named after a British river, in this case, the River Soar. It was also produced under license in the US as the Westinghouse J81.

Design and development

The Soar was developed as part of the Short Range Expendable Bomber cruise missile program of 1950. This called for a surface-to-surface missile similar to the V-1 flying bomb but jet-powered to provide much longer range, and using a new radio navigation system to give it the required accuracy at these extended ranges. Two designs were proposed, Bristol Aircraft's Blue Rapier and Vickers-Armstrongs' Red Rapier.

Red Rapier was selected as the winner after Winston Churchill returned to power in late 1951. The Vickers concept was similar to the original V-1, with a mostly cylindrical fuselage, straight wings, and conventional tail surfaces. Power was provided by three small engines located at the tips of the tail surfaces. Rolls-Royce was selected to build the engines, whilst the Telecommunications Research Establishment (TRE) began development of the guidance system. Designed to be expendable, the powerplant had a design life of 10 hours for a Red Rapier flight time of about 1 hour (range 400 nautical miles at 475 knots).

Red Rapier had been conceived as an emergency program as it was believed the Soviets were planning to start a war in 1953, before the Royal Air Force's new jet-powered bombers would be in service. As the date approached and it became clear no such attack was looming, combined with the good progress on the V-bomber designs, the program, now known as UB.109T, was cancelled. By this time the engine was running and was demonstrated at the Farnborough Airshow in 1953 on each wingtip of a Gloster Meteor flying testbed.

Applications

Development of the Soar continued for a time despite the cancellation of the UB.109T program. It was the smallest aero-engine ever made by Rolls-Royce and was an extremely simple engine with very few parts. Its starting and control systems were almost non-existent. Lessons learned in producing the Soar at low weight and cost would be applied to the next light-weight engine, the RB108 lift engine.

Looking to power a target drone design, Lockheed contracted Westinghouse to provide a similar engine. They licensed the Soar from Rolls, as the Westinghouse J81. This powered the AQM-35 missile.

It was also employed as an auxiliary powerplant for the Italian Aerfer Ariete fighter design and also considered as a JATO powerplant for other aircraft.

The Soar project was cancelled in March 1965, at a reported total cost of £1.2 million.

Specifications (RB.93 Soar)

Data from Rolls-Royce Aero Engines

General characteristics

• Type: Single-spool turbojet
• Length:
• Diameter: 15.8 in (401 mm)
• Dry weight: 267 lb (121 kg)

Components

• Compressor: 7-stage axial
• Combustors: Annular
• Turbine: Single stage

Performance

• Maximum thrust: 8.05 kN (1,810 lbf)
• Overall pressure ratio: 4.9
• Air mass flow: 13.47 kg/s (30 lb/s)
• Thrust-to-weight ratio: 6.97

See also

Related development

• Rolls-Royce RB108

Related lists

• List of aircraft engines

References

Bibliography

• Gunston, Bill. World Encyclopedia of Aero Engines. Cambridge, England. Patrick Stephens Limited, 1989. ISBN 1-85260-163-9
• Gunston, Bill. Rolls-Royce Aero Engines. Cambridge, England. Patrick Stephens Limited, 1989. ISBN 1-85260-037-3

External links

• Image of a Rolls-Royce Soar
• Image of the same engine from another angle