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Canberra WK163 - 60th Anniversary

by Ian Homer. Posted to category: General

of World Altitude Record flight

60th Anniversary of Canberra WK163's World Altitude Record flight - THIS MONDAY 28th August.

This August 28th commemorates 60 years since a Napier product help achieve the world aeroplane height record in 1957.  Fitted with a Napier Double Scorpion aircraft rocket engine, English Electric Canberra WK163 flew to a height of 70,310 feet (21,350 metres) around 20miles south of Shoreham-on-Sea.  The following is an edited article extracted from This Is Napier Vol.1, No. 2 1958.

Nose section to leading edge on Scorpion Canberra WK163. 27.9.1957


Up 70,310 feet by SCORPION

For the third time in four years, Great Britain has set up a new world altitude record for aeroplanes.  On 28th August 1957, Napier’s Chief Test Pilot, Mike Randrup, flying an English Electric Canberra fitted with a Napier “Double Scorpion” aircraft rocket engine, reached a height of 70,310 ft., beating the previous record, also held by a Canberra, by more than 4,000 ft.

Randrup was accompanied by Walter Shirley, Deputy Chief Engineer of Napier’s Flight Development Establishment, which was responsible for the design and development of Scorpion rocket engines.  They took off from Luton, home of the F.D.E., late in the afternoon and headed for Portland Bill, on the South Coast.  They then turned east where, at 44,000 ft., a few miles south of the Isle of Wight they turned north-east, at the same time bringing the “Double Scorpion” into action.  Three minutes later they had gained another 26,000 feet, and captured the record.  They were then about twenty miles south of Shoreham-on-Sea.

When it reached 70,000 ft., the Canberra was still climbing at a rate of some 8,000 ft. a minute, but the aircraft’s flying characteristics made it inadvisable for the pilot to go higher.  He therefore levelled off, shut down the rocket engine and began his descent.  The Canberra is a “sub-sonic” aircraft and has a comparatively low maximum safe flying speed.  At 70,000 ft. its stalling speed and its maximum safe flying speed are separated by a mere 20 m.p.h.  The pilot had to keep within this slender margin, or the adventure might have ended in disaster.  Every foot of additional height would have made his position more perilous.

During the final stages of the climb, practically all the Canberra’s thrust came from the “Double Scorpion”.  In that rarefied atmosphere, the two Rolls-Royce Avon turbojets could do little more that maintain the aircraft’s electrical and hydraulic services and cockpit pressurisation system.

Randrup reached his maximum height over the sea for two reasons.  Height records are measured from sea level, and the Canberra carried a radio altimeter which converts the time taken for an electrical impulse transmitted from an aircraft to reach the surface and for its echo to return into distance.  Previously, records were made from the evidence of standard altimeters, which convert pressure into height, and which take no account of the height above sea level of the earth’s surface beneath the aircraft.  The radio altimeter gives the height as a continuous reading on an oscillograph, which the pilot can see and which is photographed by cine-camera to provide proof of the achievement when the claim is submitted for official confirmation.  Atmospheric pressure does not fall at a constant rate with height, so the reading of a standard altimeter has to be corrected for pressure variation before the true height can be found.  The radio altimeter’s accuracy can be determined beforehand, or subsequently, by calibration with a special type of theodolite.

Being a branch of the Ministry of Supply whose contract the Scorpion is being developed, the RAE, Farnborough lent and installed the radio altimeter.

Map of Course, Height & Flight of Canberra WK163. 28.8.1957

Randrup and Shirley wore special clothing consisting of a partly pressurised helmet, and an inflatable jerkin to safeguard themselves against the hazards of a cockpit pressurisation failure.  If a pressurisation failure occurs, the jerkin is inflated automatically.

This clothing was designed in collaboration with the Royal Air Force Institute of Aviation Medicine, Farnborough, which has made a special study of high altitude flying problems, and from which Randrup and Shirley received valuable assistance and advice.

Airborne testing of the “Double Scorpion” in the Canberra began on 20th May 1956.  In the following 12 months, firings took place at steadily increasing heights, and when the development programme brought the Canberra within striking distance of the existing height record the decision was taken to make an official attempt to break it.  The Royal Aero Club, as representatives in the UK of the Federation Aeronautique Internationale (the body which homologates records) was asked to send a team of observers to Luton and, if the record were broken, to submit the figure to the F.A.I. for confirmation.

Canberra WK163 with Scorpion Rocket. 13.8.1957

Basically, the Scorpion rocket engine follows the general principles of the earlier missile rocket engines which Napier’s Flight Development Establishment built for the Ministry of Supply.  Structurally, however, they are different.  The missile engines were built for a short life and be easy to service and maintain.  In this respect, the Scorpions adequately meet the official specification; they can sustain many hundreds of firings, and their main components can be taken out and replaced without so much as breaking a pipe line.

Napier Double Scorpion Rocket Engine under WK163. 12.8.1957


No details can yet be given of the “Double Scorpion’s” performance but it has been disclosed that the rocket uses High Test Peroxide as its oxidant and standard turbine kerosene or gasoline as fuel.  This combination of oxidant and fuel is self-igniting and, unlike other combinations, does not need a high-energy spark plug or other type of ignitor to start combustion.  It is also safer, because the H.T.P. acts as a purge to prevent the accumulation of fuel in the combustion chamber.

To start the engine, a supply of H.T.P. is passed through a catalyst which decomposes it into free oxygen and super-heated steam.  This drives a small turbine with a double-ended shaft.  One end of the shaft carries the oxidant pump and the other the fuel pump so that the relationship between the two flows remains constant at all speeds.  The sequence is so timed that the main oxidant flow begins before the fuel flow.  After leaving the pump, the oxidant passes through a cooling jacket round the combustion chamber, and then through a catalyst which decomposes it into free oxygen and super-heated steam.  This enters the combustion chamber and creates the right conditions of temperature and pressure for the ignition of the fuel.  Before entering the combustion chamber, the fuel is used to cool the burner head.  When the rocket engine is shut down, the fuel flow stops first, and allows the H.T.P. to purge the combustion chamber ready for the next firing.

The Scorpion can be stopped and started any number of times at any height so long as fuel and oxidant are available. One advantage of the system is that special tanks for the fuel are not needed; the rocket can draw upon the aircraft’s supply.


Napier Double Scorpion Rocket Engine as fitted in WK163. 21.8.1957


Most of the honour and glory of the record must go to Randrup and Shirley, who made it, but there are a number of others who are entitled to bask in a reflected glory.  The record was the outcome of some first-class teamwork, in which many took part, although only a few can be mentioned here.

Ultimate responsibility for the rocket development programme falls upon the manager of Napier’s Flight Development Establishment, Mr C.L. Cowdrey, who first joined Napier as an apprentice at the age of 15.  Before his apprenticeship had been completed, World War I broke out and he joined the Royal Flying Corps.  After the war he spent varying periods with Fairey Aviation, Hawker Aircraft, and Rolls-Royce, re-joining Napier when the Flight Development Establishment was transferred from Northolt Airfield to Luton Airport in 1940.  He has been its manager ever since.

Another member of the Luton Staff who has had close association with the Scorpion’s development is Mr K.H. Greenly, the F.D.E.’s Chief Engineer.  He came to Napier in 1936, was transferred to Luton in 1944, became Project Designer in 1948, and was later appointed Chief Installation Designer.  His appointment as Chief Engineer was made in 1953.

Napier Double Scorpion Rocket Engine as fitted in WK163. 21.8.1957

Much credit must go to Mr E.W. Davies, the Chief Designer of the Flight Development Establishment.  He joined Napier direct from college in 1937, worked first in the Installation Drawing Office at Acton and was transferred to Luton to join the design team there.  He was appointed Assistant Designer (Propulsion) in 1950, and Chief Designer in 1957.

Mr E.W. Davies, the Chief Designer of the Flight Development Establishment stands next to WK163. 2.9.1957


Shirley’s working career began at the Royal Aircraft Establishment, Farnborough, where he was a Scientific Officer specialising in fuel and oil systems and the flight development of power plants.  He joined Napier in 1947 and became a member of the rocket design team at Luton in 1949.  In 1952 he was appointed Chief Technician, in 1956 Chief Development Engineer in charge of Scorpion engine development and design, and in 1957 Deputy Chief Engineer.  While at the R.A.E. he learned to fly and has now logged more the 450 hours as a pilot and 300 hours as a flight test observer.  He, probably, has contributed more to the development of the Scorpion than anyone else.


Randrup & Shirley wearing High Altitude Flying Suits by WK163 with Scorpion Rocket. 19.8.1957


Now 44, Randrup has been a pilot for nearly 22 years.  He learned to fly at the Kent Flying Club, Bekesbourne, near Canterbury, and before the Second World War managed a small air charter company operating from Heston, an airfield on the outskirts of London which is no longer in use.  He served with the Royal Air Force throughout the war, first as a flying instructor, then with Fighter Command, after which he tested production Spitfires at Hamble.  He became a test pilot at the R.A.E., and afterwards commanded the Engine Research and Development Flight there.  He left the R.A.F. in 1946 with the rank of Squadron Leader, and took up the appointment he still holds.

The record which he and Shirley set up was not in any way a stunt, but resulted directly from the work upon which they were engaged.  The programme called for a flight to 70,000 ft., so to 70,000 ft. they went – officially observed.


Canberra WK163 in front of the Napier Hanger at Luton. 2.9.1957


The Napier Power Heritage Trust has kindly shared this article and images from its archives with us on this special anniversary.  They hold many original images of WK163 and the development of the Scorpion rocket engine, which they have made available to us in support of our joint aim to see WK163 fly once again.  The Trust’s many interests cover all aspects of the 200 year history of D. Napier & Son Ltd including its many exploits in the aeronautical industry.  To find out more about the Company history and many achievements, or to become a member of the Napier Power Heritage Trust please visit their website or its Twitter feed at D Napier & Son Ltd



Layout drawing Scorpion Canberra. 24.10.1956



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