Right now, on a dry lake bed in Black Rock, Nevada, two teams are locked in a fierce competition. Using exotic, jet-propelled vehicles, they’re striving to break the sound barrier–on land. In the process, they’re pushing technology to its limits.
What makes the competition even more interesting is the contrast between the two teams. On the one side is the Thrust SSC (SSC stands for SuperSonic Car), whose design was carefully modelled using computers and wind tunnels before it was ever built. On the other side is the Spirit of America, whose genesis was a little more, well, informal. “Yeah, we modeled the car,” says crew chief Dezso Molnar. “We modeled it for about 42 seconds on a napkin.”
There’s a long history of this kind of rivalry and contrasting philosophy in land speed record attempts. The first official record was set on December 18, 1898, by Count Gaston de Chasseloup-Laubat of Paris, who drove an electric Jeantaud automobile at a speed of 39.24 miles per hour in Achères, France to prove that the car, designed by a Parisian carriage maker, worked well.
Within a month, Belgian engineer Camille Jenatzy drove his electric car “la Jamais Contente” (the Never Satisfied) along the same stretch of road at 41.42 mph–and whereas Chasseloup-Laubat’s car was an ordinary street vehicle, Jenatzy had specially designed his car just for speed, encasing it in a smooth, torpedo-shaped shell.
That launched a competition between the two men that lasted for several months, and culminated in Jenatzy’s record of 65.79 mph on April 29, 1899.
Since then, the Land Speed Record has advanced by fits and starts, along with technology–as indicated by the changing modes of propulsion. Jenatzy’s 1899 record, set in an electric car, fell in 1902 to a steam-powered car, nicknamed “The Whale,” driven by Leon Serpollet to 75.06 mph on April 13. Before the end of that year, the record (76.08 mph) belonged to an internal-combustion car, driven by William K. Vanderbilt, Jr. (Steam made a comeback, though; a Stanley Steamer set the record at 121.57 mph in 1906).
The record first soared above 100 miles per hour on July 21, 1904; climbed above 200 mph in 1927 (on the hard-packed sands of Daytona Beach, Fla., which would be difficult today, since all the kids on spring break would have a hard time getting out of the way), and, by 1935, had gone above 300 mph (on the salt flats of Bonneville, Utah).
By 1947 the record was within a hair of 400 mph, but that milestone wasn’t reached until August 5, 1963, when the record rose to 407.45 mph. The car? The Spirit of America, the ancestor of the car now aiming for the sound barrier in Black Rock. That first Spirit of America was also the first jet-powered, free-wheeling car to make the run. And most remarkable of all, the driver was Craig Breedlove–who today, at age 60, is back at the controls of the new Spirit of America. Breedlove was also the first man to break the 500 mph barrier (October 15, 1964) and the 600 mph barrier (November 15, 1965). Now he’d love to add the 700 mph barrier, and, most of all, the sound barrier (765 mph) to his resume.
Breedlove doesn’t hold the current Land Speed Record, though. It belongs to Richard Noble, who drove a car called Thrust 2 to 633.468 mph on Ocrtober 4, 1983. Thrust 2 was the predecessor of the Thrust SSC, and Richard Noble once again the man behind the new attempt, although, unlike Breedlove, he’s not driving this time.
As befits their very different design procedures, the Spirit of America and the Thrust SSC are very different cars. The philosophy behind the Thrust SSC is to maximize stability at high speeds. That’s the main reason it’s powered by not one but two jet engines. The Rolls Royce Spey turbojets, taken from an F-4 Phantom jet fighter, produce about 25,000 pounds of thrust each, giving the car the equivalent of more than 100,000 horsepower, but they also keep the vehicle stable by adding mass–lots of mass: Thrust SSC, even though it’s made of lightweight aluminum, carbon fiber and titanium, weighs 10.2 tons, making it the heaviest car ever built. At 54 feet long and 12 feet wide, it’s also the largest car ever built.
Computers were used to study the airflow and pressure distribution over and under the vehicle. The biggest challenge with high-speed cars is keeping them from becoming airborne. To prevent lift, the Thrust SSC has a pointed nose that droops toward the ground, which helps control the flow of air under the car. It also has vortex generators along the side designed to add turbulence to the air flowing along the fuselage and direct it along the shape of the car, special wings that can be adjusted between runs to change the weight distribution between the front and back wheels, and wheel struts that are carefully shaped to force the rear of the car down. A tail plane provides additional downward force on the back of the car; it, too, can only be adjusted between runs, because of the rules governing land speed record attempts.
Thrust SSC boasts more than 100 sensors that collect data such as air pressure and the loading of the car on the wheels. This information is store in an on-board four-megabyte hard drive for analysis after the run. Other sensors deliver data directly to the pits via radio during the run. Some of these sensors feed information to a computer that instantly alters suspension settings and other factors without any input from the driver–which, in the case of the Thrust SSC is former RAF fighter pilot Andy Green. (Green, who helped design the cockpit for the car, made sure that it includes a machmeter, an indicator usually found in supersonic airplanes that measures airspeed in terms of the speed of sound–Mach 1.)
The Spirit of America team finds Thrust SSC’s heavy reliance on computer and computer-modelling interesting, but they think their more intuitive, seat-of-the-pants approach is more likely to be successful. They’ve been carrying out remote-controlled runs to find out exactly what their car will do, believing that all model testing will tell you is whether or not you’ve made a good model, not how a real car will perform in the real world.
The Spirit of America is a relative lightweight compared to the Thrust SSC. It weighs “only” 9,000 pounds, and is ten feet shorter and four feet narrower. It’s powered by a single jet engine, a General Electric J79 which also came from a Phantom jet, which, modified to run on ordinary unleaded gasoline instead of jet fuel, produces 45,200 horsepower. Although the Spirit of America team also uses on-board sensors to find out what happens during a run, their car doesn’t have any computer-controlled suspension pieces.
The Spirit of America also steers from the front, like an ordinary car. The team has hands-on experience to prove that that steering system works well; during an attempt last year, at 675 mph, one side of the car lifted up, and Breedlove was able to bring it under control and level it out, making the world’s fastest right-hand turn in the process. Nobody knows exactly why one side of the car lifted; one theory is that shock waves on the underside of the car caused unequal lift, so since that run, various changes have been made to slow the flow of air under the car.
So how are the respective cars performing out in Black Rock? On Saturday, Thrust SSC reached a speed of 400 mph on one attempt and 554 mph on a second, but in both cases the engines were shut down prematurely by the computer, which detected something wrong–exactly what, the team doesn’t know yet. Meanwhile, Spirit of America conducted a short test sprint at 313 mph. The Spirit of America team is rebounding from financial problems, a damaged engine (it sucked in an object on September 6) and high winds and a dust storm last week. So far Spirit of America has only reached 328 mph, while Thrust SSC has run as fast as 625 miles per hour. There’s still a long way to go, and nobody knows which car has the technological edge, which will be the first to reach 700 mph, which, if either, will be the first to break the sound barrier–and what will happen when they do.
The Thrust SSC team has computer projections telling them what should happen. Craig Breedlove prefers to find out for himself.
