Blue Bird CN 7

from Wikipedia, the free encyclopedia

The Blue Bird CN 7 is a gas turbine- powered British record-breaking car that Donald Campbell first attempted to break the land speed record for automobiles in 1960 . The vehicle that had an accident and was damaged to the point of being unusable was refurbished and Donald Campbell succeeded on July 17, 1964 in setting a speed record of 648.709 km / h on the salt bed of Lake Eyre in Australia .

Blue Bird CN 7

Four and a half years to build the world's most expensive car

Campbell announced the intention to break the land speed record in 1956, and construction began in the same year. The order for this was awarded to Norris Brothers Ltd., based in Burgess Hill ( Sussex ) . (the "N" in the type designation "CN 7" ), because it had already delivered its record boat. In Coventry at Motor Panels Ltd. the vehicle was assembled. The construction was also supervised by Leo Villa, who had already worked as chief mechanic at Malcolm Campbell . From the days of Campbell senior came the car name "Blue Bird" , which was still used , and which he had decided on after visiting the Maeterlinck play of the same name . With the involvement of around 70 companies based in the country as manufacturers of special parts required for the car and as sponsors , Campbell's project did not remain a private matter, but became a decidedly British cause.

All the technical innovations available at that time were used and the car was equipped with every available electronic device. A display was projected onto the cockpit glazing from the inside , which provided information about the target and actual values ​​when accelerating - too much power could cause the wheels to spin and the car to roll. A Proteus 705 aircraft engine was converted for torque reduction on both sides and installed in a shell body , the air resistance of which was optimized by means of wind tunnel tests at Imperial College . The car should neither be sucked up nor pushed down by the air flowing along it - the latter would have improved grip, but would have overloaded the tires. A vertical tail fin was dispensed with in order to reduce aerodynamic drag; the task of stabilizing the car should be taken over by the protruding wheel covers. The Dunlop tires themselves were tested well for 765 km / h and with speeds corresponding to 800 km / h. Braking was carried out at top speeds by means of brake flaps attached to the rear of the car ; below 600 km / h, pneumatically operated disc brakes were used.

At first glance, the power-to-weight ratio was good: John Cobbs Railton Special (634.3 km / h) had around 2500 hp available to move his 3150 kg, the Blue Bird was initially a little heavier at 3600 kg, but had a 4250 hp performing turbine drive. However, a competitor, the Challenger I of the American Mickey Thompson , had an engine power in the region of the Railton Special with a weight of only 2080 kg. The Challenger I was simply pushed by an auxiliary vehicle to start, whereas the Proteus turbine was started from the outside with batteries.

Back from Bonneville with scrap and no record

He felt far superior to his admired garage builder competitors, whom he called “ hot rod boys” and in whose projects a factor of ignorance, according to Campbell, always left an incalculable risk even after repeated tests. But “imponderables” in Campbell's design were addressed by someone who had to know: Jack Brabham asked how he wanted to immediately notice the swaying of the rear end of the 9-meter vehicle in the seated position and keep it under control. The test took place on September 16, 1960 on the Bonneville Flats . Campbell had approached high speeds over the previous two weeks and now wanted to undertake a run that was specifically intended to be an acceleration test. Around a speed of 550 km / h he wanted to react to an incipient skid and did it excessively. The Blue Bird CN 7 overturned, flew through the air and hit the right side in such a way that both wheels were torn off. Campbell survived injured. “Hot-rod boy” Thompson had had similar experiences during these days and knew the antidote: If you started sliding on the salt, you should let the car take its way and then slowly bring it back to the track, one by one.

Success in Australia with the second attempt

Contrary to initial fears, the car did not have to be written off completely; together with the turbine, other parts could be reused. Sir Alfred Owen , the owner of Motor Panels , had offered to build another Blue Bird for Campbell immediately after the accident, and the interest group of British suppliers went along with them without hesitation. The car presented in 1962 ( "CN 7/62" ) did not cost another 4 million dollars and differed from the 1960s model in two details: The completely transparent canopy had been replaced by a solid synthetic resin part with a small viewing window and was located at the rear a 2.35 m high stabilizing fin. Skidding was usually the result of the wheels spinning, so "CN 7/62" received limited slip differentials . Precautions were taken to ensure that the large wheels could not saw through the body of the car in the event of an accident. All of this was reflected in a car weight of 4,300 kg; there was no longer any question of a good power-to-weight ratio.

Since a disadvantage in Bonneville was apparently the shortness of the route, British Petroleum had proposed Lake Eyre as an alternative, which was difficult to reach via unpaved roads in unfavorable terrain and was 720 kilometers north of Adelaide . Ideally, the road there could be 27 kilometers long, but the conditions in 1963 and 1964 were the exact opposite of ideal. Rainfalls, which were unusual for the local climate, had softened the salt and left the Blue Bird traces five centimeters deep. He drove as if the handbrake was on. After nerve-wracking months in which a lot of work went into preparing the slope, Donald Campbell was nevertheless able to increase the world record for wheel-driven land vehicles to 648.709 km / h on July 17, 1964.

The car has been on display at the National Motor Museum in Beaulieu (England) since 1972 .

Technical specifications

General data

Wheelbase: 4110 mm
Front / rear track: front and rear 1670 mm
Ground clearance: 96 mm
Dimensions L × W × H: 9120 × 2440 × 1445 mm
Car weight: 3600 kg to 4300 kg

Drive source

Type: Bristol-Siddeley Proteus 705 gas turbine , converted to take off power also at the rear end, power turbine independent of the compressor part
Power: 4250 hp at 11000 rpm
Fuel tank: 2 tanks of 96 liters each ("CN 7/62" a 60 liter tank)

Power transmission

Drive: all wheel drive
Coupling: No
Transmission: Single stage, David Brown final drives 3.64: 1 with spiral bevel gears ; front drive via freewheel , non-positive drive at the rear

landing gear

Frame: Main frame support made of perforated aluminum profiles, body as a monocoque made of sandwich panels with a honeycomb core , outer skins made of 1.2 mm sheet metal (light metal alloy), support core made of synthetic resin-bonded 0.05 mm sheet metal (light metal alloy), 19 mm high, 6 mm mesh width
Axes: Hydropneumatic running gear with wheels individually suspended from wishbones, spring shock absorber units from Girling
Brakes: Brake flaps arranged at the rear for speeds of over 600 km / h, including internal pneumatic disc brakes from Girling.
Steering: Burman steering gear, recirculating ball screw operated by chains and pinions
Bikes: Dunlop disc wheels made of steel, removable rim
Tires: 7.0 × 41 by Dunlop, 1321 mm outside; 0.5 mm natural rubber protector on a carcass made of four-ply artificial silk

Picture gallery

  • Blue Bird CN 7

  • Blue Bird CN 7

  • Blue Bird CN 7

swell

Individual evidence

  1. ↑ Donald Stevens: Bluebird CN7: The Inside Story of Donald Campbell's Last Land Speed ​​Record Car , Veloce Publishing, Poundbury 2010, p. 35

Web links

Commons : Bluebird-Proteus CN7  - collection of pictures, videos and audio files