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Object of the Month

Viper Jet Engine

The Armstrong Siddeley Viper is a British turbojet engine developed and produced by Armstrong Siddeley and then by its successor companies Bristol Siddeley and Rolls-Royce Limited. It entered service in 1953 and remained in use with the Royal Air Force, powering its Dominie T1 navigation training aircraft until January 2011.

jet engine


This weeks marks the anniversary of the first ground tests of the jet engine in Rugby.  On 12 April 1937 the tests began at the British Thomson-Houston work, Brownsover Hall, Rugby led by the pioneering inventor Frank Whittle.

Whittle's account of that time gives an indication of the danger involved.

I had the fuel pump switched on.  One of the test hands then engaged the starter coupling (which was designed to disengage as soon as the main rotor on the engine over-ran the starting motor) and I gave hand signals to the man on the starter control panel.

The starter motor began to turn over.  When the speed reached about 1000rpm I opened the control valve which admitted fuel to a pilot burner in the combustion chamber, and rapidly turned the handle of the hand manetro to ignite the finely atomised spray of fuel which this burner emitted.  An observer, peering through a quartz observation window in the combustion chamber, gave me the full "thumbs up" sign to show the pilot flame was still alight.

I signalled for an increase on speed for the starter motor, and as the tachometer indicated 2000 rpm I opened the main fuel control valve.

For a second or two the speed of the engine increased slowly and then, with a rising shriek like an air-raid sire, the speed began to rise rapidly, and large patches of red heat became visible on the combustion chamber casing.  The engine was obviously out of control.  All the BTH personnel, realising what this meant, went down to the factory at high speed in varying directions.  A few of them took refuge in nearby large steam engine exhaust casings, which made useful shelters.

I screwed down the control valve immediately, but this had no effect and the speed continued to rise, but fortunately the acceleration ceased at about 8000 rpm and slowly the revs dropped again.  Needless to say this incident did not do my nervous system any good at all.  I have rarely been so frightened.

Testing continued at Rugby until BTH insisted that further trial runs had to be conducted at a site away from the factory.  Work therefore moved to a disused foundry near Lutterworth.

Sir Frank Whittle's genius is remembered in Rugby near the entrance to Caldecote Park with a sculpture by  Stephen Broadbent.

Find out more about Sir Frank Whittle at the Warwickshire Archives