1000 mph Car

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Strapped into a custom built seat, Andy Green prepares for the ride of his life. The pancake-flat desert stretches out for miles ahead. The computer indicates all systems are normal. He eases off the brakes and puts his foot down on the throttle. The jet engine roars into life. In precisely 42.5 seconds he’ll be travelling 1000 mph. In a car.

“It’s almost impossible to tell the difference between going supersonic in a car and in an aircraft,” says Green. He is the only person on Earth who can say that from personal experience. Green was a fighter pilot for the UK Royal Air Force for 20 years, and he is also the fastest man on wheels. In 1997, driving a vehicle called ThrustSSC, he set the world land speed record of 763 miles per hour, becoming the first and only person to break the sound barrier in a car (761 mph under standard conditions). Now, together with the Bloodhound SSC design team, he’s attempting to do it all over again, and then some.

This time there’s competition. A three-way race is developing, with two other teams, one from North America and the other from Australia, vying to wrest the record from the Brits. The first step will be to break the existing record and get past 800 mph. If that succeeds, the next stage is to attempt 1000 mph (1609 kilometres per hour). “That’s what we’re designing the car for,” says Ron Ayers, chief aeronautic engineer on the Bloodhound project.

All three competing vehicles have wheels, brakes and a steering wheel, but that’s pretty much where the similarity with conventional cars ends. Getting up to the speed of sound and beyond poses challenges that a normal car will never encounter, requiring some radical design and engineering.

For example, the wheels of a 1000 mph car will need to rotate at over 10,000 revolutions per minute, many times faster than on an ordinary car. This rate of spin entails an acceleration of almost 50,000 g at the rim, generating forces that would easily tear conventional wheels apart. Instead, this car will need wheels of solid titanium, or more likely carbon-reinforced aluminium. What’s more, as the vehicle approaches the speed of sound, it produces a frontal shock wave which liquefies the earth ahead, so the wheels end up carving through ground, rather than simply rolling over it. On top of all that, beyond 250 mph, airflow starts to become a more important consideration in controlling the vehicle than traction on the ground. At this speed, the wheels begin to behave like rudders or aerofoils, and driving the car becomes more like controlling a speedboat or flying an aircraft. “Our biggest single concern is to make sure the vehicle stays on the ground,” says Green.
As the car approaches the speed of sound, it produces a shock wave which liquefies the earth ahead

Creating a “car” that takes account of all these factors means exploring unchartered territory in aerodynamics and vehicle mechanics. “No one has ever designed a car to go this fast before,” says Green, “so we’ve got to develop and test, develop and test… it’s an ongoing research project.”

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Green hits 79 mph. At this stage he would be eating the dust of an average sports car, but Bloodhound is an automotive wolf in sheep’s clothing. Green holds steady, and 5 seconds later unleashes the first of his secret weapons: an afterburner which dumps extra fuel into the jet engine, stoking it up to full power.

Bloodhound SSC will use a retired Eurofighter jet engine to provide the first-stage thrust for the car. In that respect it resembles ThrustSSC, which was powered entirely by two jet engines. But according to Ayers, that set-up won’t be good enough to reach 1000 mph. “The large front inlets [for the jet engines to take in air] on ThrustSSC produced huge shock waves at supersonic speed,” he says. “This means we couldn’t get any more than a 5 per cent increase in speed using that design.”

The joint US-Canadian team, North American Eagle, begs to differ. They are going entirely with jets. Instead of designing a car from scratch, they have taken the fuselage of a scrapped F-104 Starfighter aircraft, added the engine from an F-4 Phantom supersonic fighter-bomber bought from a surplus seller, and bolted on some wheels. “We know the aircraft can do around 1500 mph, so if we can do just half of that on land we’re already pretty close to the record,” says Ed Shadle, the car’s driver and co-owner.

Unlike their competitors, North American Eagle is already built and rolling. Shadle has done 27 runs so far, pushing the car to 400 mph to test the parachute systems and brakes, and to collect data to model what will happen at higher speeds. He is now refining the wheels and aerodynamics. “We’re hoping to go after the record on the Fourth of July 2010,” he says.

As yet he doesn’t know where that attempt will be made, because his decision to go with jets alone has presented him with a very difficult problem: the sheer length of track he will need to accelerate to 1000 mph and then decelerate to a stop. The terrain has to be as flat as glass; any bumps might send the car off-track