Silver Bullet (Sunbeam land speed record car)

Infobox Automobile generation


name =Silver Bullet
manufacturer =Sunbeam of Wolverhampton
production =one
body_style = Land speed record car
layout =
platform =
engine = Two Sunbeam 2,000hp supercharged V12 aero engines, totalling 48 litres
transmission =
wheelbase =
length =
width =
height =
weight =
fuel_capacity =
designer =

The Sunbeam "Silver Bullet" was the last attempt on the land speed record by Sunbeam of Wolverhampton. It was built in 1929 for Kaye Don. Powered by two supercharged aero-engines of 24 litres each, it looked impressive but failed to achieve any records. cite web
title=A History of Sunbeam
url=http://www.sunbeam.org.au/history/] cite web
title=Silver Bullet photo
url=http://www.sunbeam.org.au/history/bullet.jpg
format=photograph]

Sunbeam's 1927 200 mph land speed record won with the Sunbeam 1000HP had been broken by 1929, and the company decided to build a car capable of reaching 250 mph so as to recover it. Only aero engines offered enough power to do this, and such a car would also provide a test bed for developing a new generation of Sunbeam aero-engines.

Sunbeam 2,000 hp engine

Sunbeam decided to develop a new aero engine of 2,000 hp, and the car would be powered by two of them.

This new engine was a water-cooled V-12 with a 50° angle between the banks. Ideal balance usually favours an angle of 60°, but this choice made the engine narrower overall. Cylinder bore was 140 mm and stroke was 130 mm, for a capacity of 24.02 litres. This oversquare geometry was a first for Sunbeam, but encouraged a high-revving and thus more powerful engine.

The engines were supercharged, using a large centrifugal blower, geared to 17,000 rpm. This was increasingly common aero engine practice of the time, in both the Napier Lion and the Rolls-Royce R-type, but again was a first for Sunbeam.

When installed in the record-attempt car the engines had an unusual cooling system using melting ice rather than a radiator. This avoided the drag of an open radiator, but obviously could only cool for as long as the ice lasted. It was a workable system for land speed records, used by the contemporary Golden Arrow and more recently by the JCB Dieselmax. "Silver Bullet" had an 11.5 cu.ft ice tank, filled with 5.5 cwt of ice before each run, and a one gallon mixing tank in the nose. cite web
title=The 2,000 HP Sunbeam
url=http://www.localhistory.scit.wlv.ac.uk/Museum/Transport/planes/SunbeamEngines11.htm
publisher=Wolverhampton Museum of Industry]

Photographs

Photographs of the car are rare, although there are some at the Brooklands photo archive. These show it outside Delaney & Sons. garage, a popular location for racing in this era. cite web
title=Outside the Delaney & Sons Sunbeam-Talbot garage
url=http://www.brooklandsarchives.com/Gallery_D1/target18.html
publisher=Brooklands photo archive] Some also show close-ups, including the innovative rear aerofoil that could be adjusted to generate downforce. cite web
title=Nose-on view
url=http://www.brooklandsarchives.com/Gallery_S2/target40.html
publisher=Brooklands photo archive] cite web
title=Rear three-quarter view, aerofoil raised
url=http://www.brooklandsarchives.com/Gallery_S2/target39.html
publisher=Brooklands photo archive] cite web
title=Rear views, aerofoil lowered
url=http://www.brooklandsarchives.com/Gallery_S2/target41.html
publisher=Brooklands photo archive]

Specifications

pistonspecs

type=12-cylinder liquid-cooled 50° vee piston aircraft engine
bore=140 mm (5.512")
stroke=130 mm (5.118")
displacement=24.01 litre (1465.4 cuin)
length=
diameter=
width=
height=
weight=
valvetrain=
supercharger= centrifugal single-impeller at 17,000 rpm
turbocharger=
fuelsystem=
fueltype=
oilsystem=
coolingsystem=water from melting ice
power=2,000 hp (claimed) 4,000 hp for the car

specpower=
compression=
fuelcon=
specfuelcon=
oilcon=
power/weight=
designer=Louis Coatalen

Unsuccessful record attempts

Competition for the land speed record in between Segrave's Golden Arrow and Malcolm Campbell's new Bluebird was fierce, so the car was built quickly, working around the clock in shifts. This left little time for thorough static testing of the engines, made even worse as only two engines were ever built and so the only engines available for testing were the race engines themselves. "Silver Bullet" first appeared in public on 21st February 1930.

Following the other teams, the first record attempt was to be made on Daytona Beach, in Florida, with Kaye Don driving. The car arrived at Daytona on the 8th March and Louis Coatalen himself on 16th. The record attempts went poorly though, with engine reliability problems and the car proving difficult to control. The fastest speed attained was 186 mph, well below Sunbeam's own record of three years earlier.

After the team returned home, further attempts were made to improve the car with testing on Pendine Sands. cite web
title=History of Pendine
url=http://www.sandspeedwales.co.uk/5907.html] cite web
title=Silver Bullet, nose on
url=http://www.sandspeedwales.co.uk/mediac/400_0/media/DIR_48968/Kaye~Don~32$282$29.jpg
date=1932
format=photograph] cite web
title=Silver Bullet, side on
url=http://www.sandspeedwales.co.uk/mediac/400_0/media/DIR_48968/Kaye~Don~1932$282$29.jpg
date=1932
format=photograph]

Sunbeam aircraft engines had never recovered from the financial effects of the end of the Great War.cite web
title=The End of an Era
url=http://www.localhistory.scit.wlv.ac.uk/Museum/Transport/planes/SunbeamEngines12.htm
publisher=Wolverhampton Museum of Industry] Coupled with the Depression of the 1930s, Sunbeam simply could not afford a competition program of this scale. Although other UK car companies even did well in this period, Sunbeam did not and went into receivership in 1935.

The "Silver Bullet" was sold to Jack Field, a Southport hotelier and garage owner. He tested the car on Southport beach, scene of Segrave's earlier success with the Sunbeam Tiger, but couldn't solve its problems and eventually the car was scrapped. cite web
title=The "Silver Bullet"
url=http://www.localhistory.scit.wlv.ac.uk/Museum/Transport/Cars/Sunbeam/Bullet.htm
publisher=Wolverhampton Museum of Industry]

See also

* Sunbeam 1000HP
* Golden Arrow

References