DONALD CAMPBELL

After Sir Malcolm Campbell's death at the end of 1948, Donald Campbell took up a number of land and water speed challenges. Through K4, to K7 and the CN7, the logical progression (taking into account the US rocket cars) was to wrestle those records back to Britain. If DC had survived the K7 flip, we wonder how long it would have been before the speed king got the courage to strap himself into the cockpit of the CN8 - or if Tonia might have talked him out of it.

THE ROCKET CAR

The Bluebird Mach 1.1 or CMN-8 was a design for a rocket-powered supersonic land speed record car, planned by Donald Campbell but thwarted by his subsequent death during a water speed record attempt in Bluebird K7 in early 1967.

Donald Campbell decided a massive jump in speed was called for following his successful 1964 LSR attempt in Bluebird CN7. His vision was of a supersonic rocket car with a potential maximum speed of 840 mph, referred to as Bluebird Mach 1.1. Norris Brothers were requested to undertake a design study.

Campbell, ever superstitious, chose a lucky date to hold a press conference at the Charing Cross Hotel on 7 July 1965 to announce his future record breaking plans, responding to the record set by Craig Breedlove:

“ ... In terms of speed on the earth’s surface, my next logical step must be to construct a Bluebird car that can reach Mach 1.1. The Americans are already making plans for such a vehicle and it would be tragic for the world image of British technology if we did not compete in this great contest and win. The nation whose technologies are first to seize the “faster than sound” record on land will be the nation whose industry will be seen to leapfrog into the 70s or 80s. We can have the car on the track within three years" ”

Bluebird Mach 1.1 was to be rocket-powered. Ken Norris had calculated using rocket motors would result in a vehicle with very low frontal area, greater density, and lighter weight than if he went down the jet engine route. Bluebird Mach 1.1 would also be a relatively compact and simple design. Norris specified two off-the-shelf Bristol Siddeley BS.605 rocket engines. The 605 had been developed as a take-off assist rocket engine for military aircraft and was fuelled with kerosene, using hydrogen peroxide as the oxidizer. Each engine was rated at 8,000 lbf (36 kN) thrust. In Bluebird Mach 1.1 application, the combined 16,000 lbf (71 kN) thrust thrust would be equivalent of 36,000 bhp (27,000 kW; 36,000 PS) at 840 mph (1,350 km/h).

The compact size of the rocket motors enabled Norris to design a vehicle with a very low cross-sectional area. A dart-like configuration was chosen, with two closely paired front wheels behind the nose-mounted cockpit and two rear wheels 8 ft (240 cm) apart, faired into stabilising fins. The design was expected to be inherently stable in a straight line. The main structure of the car was both elegant and simple, yet it would ensure significant torsional strength and also allow separate storage of the two liquids used as the propellant. The main chassis would be a flat box-like structure with internal rib strengthening, not unlike the chassis of Bluebird CN7. This would provide the frame to which were attached the rocket engines, one above and one below, as well as the propellant tanks – hydrogen peroxide on top, kerosene underneath. The frame would also house the torsion bar rear suspension. Clad in a slim pencil-shaped body with rear outrigger fins, the vehicle would feature a recumbent driving position. The wheels were to be machined from solid aluminium billets. As they were not required for propulsion, but merely to support the car, there would be no need for tyres.

Various dimensions were considered and eventually a full-scale mock-up of the car was built measuring 27 ft 8 in (843 cm) long, 8 ft 6 in (259 cm) wide at the rear wheels, with an overall height of just 3 ft 7 in (109 cm). Ground clearance was projected to be only 4.5 in (11 cm), giving Bluebird Mach 1.1 a very low centre of gravity and roll centre. The predicted weight was 1,600 kg (3,500 lb) including propellants. Bluebird Mach 1.1 would thus have a power-to-weight ratio of 22,000 bhp (16,000 kW; 22,000 PS) per tonne.

After Campbell's death, the project continued at a low key for some years, still involving Leo Villa, with Norris as Design Consultant from 1968-1971. In 1973, Nigel McKnight became involved, but failed to raise the necessary sponsorship.

The model disappeared and its present whereabouts are unknown. It was possibly buried in building foundations, along with the wrecked sponsons of the Bluebird K7.

The project is little-known today, although some model makers offer replicas and there is much (light hearted) speculation as to how the vehicle may have looked in its final form.

SPECIFICATIONS

This is a model of the rocket powered CMN8 Bluebird that was never to be, but was very much on the cards. The CMN8 was a very clean design that shares rear wheel features with other vehicles. The land missile was mocked up full size and kept on Donald's drive for a while. Who knows, one day there may be a JW9 rocket/jet powered car - perhaps after a few more haggis and the sound of the bagpipes to a full moonlit night.

THE ROCKET AGE

It all began with Hitler's V1 rocket during World War Two. A rocket engine, or simply "rocket", is a jet engine that uses only stored propellant mass for forming its high speed propulsive jet. Rocket engines are reaction engines and obtain thrust in accordance with Newton's third law. Since they need no external material to form their jet, rocket engines can be used for spacecraft propulsion as well as terrestrial uses, such as missiles. Most rocket engines are internal combustion engines, although non-combusting forms also exist, such as hydrogen peroxide engines.

All current spacecraft use chemical rockets (bipropellant or solid-fuel) for launch, though some (such as the Pegasus rocket and SpaceShipOne) have used air-breathing engines on their first stage. Most satellites have simple reliable chemical thrusters (often monopropellant rockets) or resistojet rockets for orbital station-keeping and some use momentum wheels for attitude control. Soviet bloc satellites have used electric propulsion for decades, and newer Western geo-orbiting spacecraft are starting to use them for north-south station-keeping and orbit raising. Interplanetary vehicles mostly use chemical rockets as well, although a few have used ion thrusters and Hall effect thrusters (two different types of electric propulsion) to great success.

Rocket engines as a group have the highest exhaust velocities, are by far the lightest, but are the least propellant efficient (have the lowest specific impulse) of all types of jet engines.

ROCKET SAFETY

Rockets have a reputation for unreliability and danger; especially catastrophic failures. Contrary to this reputation, carefully designed rockets can be made arbitrarily reliable. In military use, rockets are not unreliable. However, one of the main non-military uses of rockets is for orbital launch. In this application, the premium has typically been placed on minimum weight, and it is difficult to achieve high reliability and low weight simultaneously. In addition, if the number of flights launched is low, there is a very high chance of a design, operations or manufacturing error causing destruction of the vehicle. Essentially all launch vehicles are test vehicles by normal aerospace standards (as of 2006).

The X-15 rocket plane achieved a 0.5% failure rate, with a single catastrophic failure during ground test, and the Space Shuttle Main Engine managed to avoid catastrophic failures in over 350 engine-flights.

SIR MALCOLM CAMPBELL'S BLUE BIRDS

Sunbeam

Napier Lion

Rolls Royce

K3

K4

DONALD CAMPBELL'S BLUEBIRDS

K7

CN7

CNM8