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Spirit of America - test run - Bonneville

The World's Fastest Automobile Race

Sports Car International Magazine
By Sam Low

The World Land Speed Record
The date is October 15, 1964. Craig Breedlove pilots Spirit of America
I through the flying mile at Bonneville's land speed record course. As he exists the speed traps at over 550 miles an hour, flame extends twelve feet beyond the car's jet exhaust. A white plume of salt rises from her wheels. In the cockpit, Breedlove presses a button to ignite a powder charge in a parachute canister at the car's tail. He feels a slight tug as his braking chute opens. Then nothing. The chute has failed. Streaking past a marker indicating three miles of track remaining, the speedometer indicates 460 miles an hour. Craig deploys his emergency chute. Nothing. At the end of the track, he tries his disc brakes. His foot goes to the floor. Shaped to slip easily through the air, Spirit of America continues off course with great velocity, glances off a telephone pole, climbs an earthen dike that constrains a pool of water, and flies. The vehicle skips across the pool in a series of ever tightening arcs and comes to rest, nose down, with her cockpit in six feet of water. Breedlove emerges unscathed and with a new world record of 526.277 miles an hour. A few months earlier, Glenn Leasher had perished in the wreckage of his jet powered car. In 1963, Athol Graham died when his City of Salt Lake crashed on the same course.

Craig - his dogs - and the media

Time warp forward thirty-one years to October 21st, 1996. Breedlove, now 59 years old, still looks the youthful "Captain America" who captured the land speed record five times and set a record of 600.61 MPH in 1965. He is a PR man's dream - handsome, articulate impassioned. Craig first traveled to the Salt Flats on the window ledge of a '46 Ford hot rod driven by a neighborhood teenager. He was then fifteen. From that moment he has focused his life on the land speed record - often at the expense of family and personal fortune. Now, after a thirty year enforced leave of absence when public interest shifted away from speed, Craig has created a new Spirit of America to break the record which, in the interim, has been set by Englishman Richard Noble at 633 miles an hour.

Spirit is unloaded from transporter

Spirit of America
Every engineer knows that it's a mistake to anthropomorphise a machine, yet with Spirit of America the temptation is irresistible. Pure white, 44 feet from tapered nose to her stainless steel afterburner, she resembles a rocket ship that addresses the earth rather than the havens. Air intakes that feed her 43,000 horsepower General Electric J79 jet engine protrude from each flank and rise gracefully, like a Vulcan's ear, to a point. A dorsal fin arcs serenely aft, then spirals home like the knurl of an upturned Stradivarius - a steering vane. Two rear wheels of very large diameter are encased in pods which are cantilevered for stability and raked back for aerodynamic efficiency. The pods terminate in a scimitar's curve. This new Spirit of America was fashioned by Craig Breedlove with a vision that proportioned equal weight to speed and beauty.

Riding in Spirit's sloping nose, Breedlove intends not to just beat Noble, but to be the first to exceed 700 miles an hour. Then, in what many regard as a fool-hardy extreme, he will accelerate fast enough to penetrate the sound barrier. It is a challenge that Richard Noble has accepted. He, too, has built a car capable of supersonic speed which he calls "Thrust SSC (supersonic car)" after the original machine, Thrust II, which propelled him to the world record. Should either of these men realize their intent, they will be exploring what scientists call a technological and scientific frontier.

The Sound Barrier

Dr. Seymour Bogdonoff is the Robert Porter Patterson professor of Aerospace Engineering at Princeton University. He is 75 years old, slender, with active gray eyes and an open face. Bogdonoff was a scientist with NACA (the organization that later became NASA) during the period when aircraft were approaching the speed of sound for the first time.

"There is an eerie parallel between what is taking place today with these land speed cars and what happened in the air during the forties," Bogdonoff told me in his cramped office at Princeton's Gas Dynamics Laboratory. "There was no sound barrier. It was an ignorance barrier. We tried to push planes designed for 400 miles an hour through the air at 700 miles an hour and they crashed."

"Imagine you are walking and that at the same time you are singing a song," Bogdonoff explains. "The notes of the song spread out in a circle around you at the speed of sound. Sound waves are infinitesimal pressure disturbances. They fan out ahead of you. Now imagine that you are riding in a car, and you speed up. Those waves ahead of you are still going faster than you are but now they are closer together. Behind you, the waves are further apart because you are moving away from them. If you accelerate to go as fast as the sound waves, all those waves end up right there with you. Each of them is infinitesimal, but if you stack a whole batch of them up, they become finite. They become a shock wave."

When a modern airplane goes fully supersonic, the shock wave trails away from the craft much like the wake of a boat. Behind the shock wave, air pressure increases dramatically. When the wave whacks the ground, the pressure change is felt as a sonic boom which may be powerful enough to shatter windows. Modern supersonic aircraft fly high to reduce the impact of their shockwaves, but when a land speed car achieves supersonic speeds only inches from the earth's surface, the resulting pressure increase may lift the vehicle off the ground. The ensuing flight would be dramatic, of rather short duration, and almost certainly fatal. "Breedlove and Noble are trying to accomplish a very dangerous thing," Professor Bogdonoff told me. "If they don't know what they're doing, it's going to be like those poor pilots we killed in the late forties."

Technician checking Spirit's electronics

Black Rock
The small town of Gerlach, Nevada, population 350, huddles against the flank of the Granite Mountains. It is a monotonous landscape that presents muted earth tones as far as the eye can see. North of the town the land continues in its unbroken flatness but now shifts color from yellow and tan to a gray pallor which marks the beginning of the Black Rock Playa - alkaline silt - in some places reported to be 10,000 feet deep, all that remains of ancient Lahontan Lake which formed at the end of the last ice age. The dried and caked lake bottom, eighteen miles long from northeast to southwest, is the world's perfect land speed record track.

On October 21st, 1996, I travel to Black Rock to observe Craig Breedlove and his team as they attempt to set a new land speed record. Crew chief Dezso Molnar takes me on a tour of the car. I am quickly made to appreciate that its elegant design stems from a simple motto, "keep it simple, stupid." Take the brakes, for example. The car will be slowed from top speed by a parachute that will pop out of its nest under the jet engine, pretty standard fare for high speed vehicles. But to come to a stop, Craig has employed a novel device.

"Down here we have what we call our Fred Flintstone Brake," says Dezso, pointing to a metal ski protruding from Spirit's nose. It is designed to extend and drag on the ground once the parachute has bled the car's speed to about 75 miles an hour.
v "The brake is hydraulically actuated. It will dig into the dirt or whatever. This car has very low drag and a lot of mass, nine thousand pounds, so it will just cruise and cruise and cruise if we didn't have something to stop it."

Although it may seem a simple device, the ski brake is an example of the way Craig thinks through every detail of his car and often comes up with novel solutions. To stop a car with normal brakes, a pad of heat resistant material acts on discs attached to the wheels which, in turn, act through their contact patches on the ground. Adding up the area of the contact patches of all of Craig's wheels gives about 200 square inches. But the ski brake will spread more than 240 square inches of material to the ground, and it will do so directly, without any intermediary actuating devices like calipers or pads or discs. The brake is both simpler and more effective.

"Getting a car like this going is not the problem," Craig says, "it's getting it stopped. It takes about a mile just to shut off the engine when I'm traveling a mile every six seconds. The car is a voracious consumer of distance. It eats land."

Spirit at Bonneville

The Fury of the Wind
In spite of the fact that Richard Noble and Craig Breedlove have been locked in an advanced form of technical combat for years, their obsession with speed has also created a unique bond. It is like that shared by the cognoscenti of odd subjects, a love of frogs, say, or plasma physics, to which you must add the bond of shared danger. In 1983, when Richard Noble was attempting to set a new land speed record, Craig traveled to Black Rock to watch. He ended up by helping.

"I remember that when Richard was trying to break the record he was having trouble getting beyond about 620 miles an hour," Craig recalls, "so I talked with him about the angle of attack that would be necessary to offload some downforce to get the record. We went from a zero angle of attack to .028 positive, a fraction of a degree positive, and then I left. He went through the record on the next run. He was "land bound." Until some of the rolling drag was reduced, the car was not capable of exceeding the record."

The force of the air acting on a vehicle increases with the square of the vehicle's speed, so a slight misalignment of a record car with the wind may cause it to either lift - to fly - or to press down on the ground with such force that rolling drag inhibits its speed. By increasing Thrust's angle of attack very slightly, Noble increased lift to reduce rolling drag and take the record. But that infinitesimal adjustment, only .028 of a degree, was a calculated risk. Reflecting back on the moment, Richard Noble says, "Thrust II nearly flew. We got to within seven miles an hour of takeoff and at those speeds with dynamic pressures of ¾ of a ton for every square foot of body work, it would have been a 40 G takeoff."

Noble's new car has twin engines slung on either side of it's fuselage so it presents rather large surfaces for the air to work against. To accommodate the difficulty of aerodynamically trimming Thrust SSC, Noble has designed what he calls "an active ride" system. Sensors mounted on the wheels detect the amount of aerodynamic force pressing down on them. They feed that data through a ganglia of wires into a computer which assesses the car's balance in microseconds and sends orders to hydraulic mechanisms to raise or lower the tail of the car - to adjust the angle of attack - or, as Noble puts it, the incidence of the car to the wind.

"We can vary incidence at any mach number or increment of mach number," Noble says. "At mach .9 we might find a minus quarter of a degree of incidence is appropriate and at mach .93 we might want a different ride incidence. We are optimizing the car for changing running conditions."

Breedlove, on the other hand, has designed a car that does not address the wind with large surfaces. Spirit is pencil thin, it's underbody rounded. He does not employ "active ride," but he does have numerous aerodynamic surfaces that can be adjusted to control its balance at the beginning of each run.

Spirit of America base station

A Perfect Run

Black Rock, Nevada. On Wednesday, October 23rd, a rain shower slicks the playa, then dries quickly under the baking sun. At 3:15 PM Craig shoehorns into Spirit's cockpit and takes her to 441 miles an hour on the first high speed test. With the exception of a slight case of parachute misbehavior, the car performs flawlessly.

During the night, a low pressure system moves down from Canada. A finger of disturbed weather extends across the Black Rock desert, bringing rain. In the morning, ragged clouds scud over Gerlach and water stands in ugly gray puddles. The results of the previous day's run buoy the team's spirits, but winds sweeping off the Granite Mountains gust to 60 miles an hour. The desert is closed.

"Waiting, it's one of the most difficult things we have to do," a crew member tells me. "But the record should be ours if the weather will just cooperate."

Shock Waves
But Breedlove and Noble are after more than merely setting a new speed record. Both men want to be the first to break the sound barrier on land - the ultimate test of technical ingenuity and human courage. "It's something that I've had years to think about," Breedlove once told me, "every single aspect of it. I go to bed almost every night thinking about it and I wake up the next morning with the same thought in mind."

One of the things that most occupies the minds of both Breedlove and Noble are those shock waves that will stream off their vehicles when they reach the speed of sound. It's the same phenomenon that caused pilots and scientists to think of an invisible "barrier" that destroyed aircraft trying to go supersonic in the '40's.

Many of the incidents experienced by early experimental airplanes actually occurred before they went supersonic, at speeds between Mach point eight and Mach one, a dangerous regime that aerodynamacists call "the transonic zone," where local shock waves form on an aircraft's control surfaces. Such local shock effects can be expected to cause problems for both Spirit of America and Thrust SSC. Spirit of America, for example, uses control surfaces similar to an aircraft's to achieve aerodynamic balance - trim tabs mounted on the trailing edge of wings which encase its two rear axles. If Spirit's nose is pitching up, Breedlove will deflect the trim tabs down. If the nose pitches down, the tabs will be adjusted up. At high speeds, the craft's aerodynamic balance depends both on the precise positioning of these trim tabs and a smooth flow of air over them. But in the transonic zone, the air is almost never smooth.

Consider Spirit of America as it approaches the speed of sound, about 760 miles an hour on an average Fall day. Imagine that she is doing 700. Air particles speed up as they pass over the curved surface of her rear axle wings. Imagine now that they exceed the speed of sound and a local shock wave appears - it's a little one, so in itself it's not very dangerous - but what happens next is. At the shock wave, air pressure soars, which disturbs the orderly flow of air over the wing and causes eddies to form, nasty swirling vortices of air which spill over Breedlove's trim tabs. "If the air is not attached to the wing in a nice orderly flow, the trim tabs may be in a region where there is very little air flow over them and so they will not work as Breedlove designed them to," says Seymour Bogdonoff. Depending on a variety of factors this will, in turn, cause the nose to pitch up or down, and Spirit of America will attempt to travel to China - either by piercing the earth or by achieving orbit.

Pressure Reversals

Both Breedlove and Noble are convinced that they experienced local shock waves during previous record runs. The phenomenon occurred at only about 600 miles an hour, well below the speed of sound. In both cases, the shock waves seem to have built up beneath the car where the air is sped up as it is compressed between the car's bottom and the ground. At subsonic speeds, this produces an area of low pressure which sucks the car to the pavement, an effect called downforce which is used by modern racing machines to increase traction. But this effect may actually reverse as the car approaches the speed of sound.

"At lower speeds, you get a venturi effect beneath the car and a venturi gives you suction and suction sucks the car down, " says John Ackroyd, the designer of Richard Noble's earlier record setting car. "On our record car, we had plenty of downforce, enough to be driving the wheels into the desert and costing us a lot of drag. But that seriously reversed when the air beneath the car went supersonic. It's a fact that a supersonic venturi, far from creating suction, creates pressure and pressure beneath the car creates lift. The minute we hit a very high speed, you could see the dust spurt out sideways from underneath because the pressure was rising there and pumping the dust out."

The effect of this pressure reversal could of course be catastrophic. Imagine either car proceeding at near supersonic speeds, perfectly balanced by the flow of air over their surfaces, with just enough air pressure forcing them down so they will not fly - but not so much pressure that they are slowed by rolling resistance. Now imagine that a pressure reversal occurs beneath the car, perhaps substantially pitching the car's nose up into the fierce stream of wind…

Breedlove, as usual, has adopted a common sense approach to dealing with this problem. Spirit's underbody sections are both rounded and vee-shaped which, he hopes, will give the increased pressure less surface to work on.

Noble's critics argue that Thrust SSC's large flat bottom will provide an ideal surface for even the slightest pressure change to react against and hence increase danger as the car enters the transonic zone. But noble is sanguine. He has tested his car using advanced computational fluid dynamics, a computer program that solves for the flow of air over its surface and plots where shock waves will form. He has also affixed a 1/25th scale model on a rocket sled and run it at supersonic speeds over the ground, measuring the effect of the shock waves on the model. The two different techniques produced the same result, giving Noble confidence that he knows exactly what will happen when Thrust II enters the transonic zone.

When I asked Noble what this research revealed, he told me, quite reasonably, that the results had to be kept secret until after the "race" had been won. But by using a calculated scientific approach, both Richard and his aerodynamacist, Ron Ayers, are convinced that they have indeed achieved a revolutionary understanding of supersonic air flow. "The idea of a vee-shaped fuselage (like Spirit's) means nothing," says Ayers, "because nobody who shaped it that way actually knows what happens with the shockwave. But we do. Through the rocket test I know exactly what happens to the airflow under the car and to the shockwaves. It's like we've tackled the problem head-on, where others have tended to shy away from it and avoided actually investigating it."

If it is fair to liken science to a river of knowledge, then Richard Noble and Craig Breedlove stand on opposing banks of the river. It is not just that they are two very different personalities, but that they have arrived at the river by traveling through vastly different terrain. Breedlove represents an American path toward speed which curves through the rough and tumble yet immensely pragmatic world of drag racing. In England, where such sport is almost non-existent, Noble has taken a route which lofts through the theoretically charged realms of aerospace research.

"Richard is trying to scientifically model the physics of supersonic travel," Craig once explained to me, "but using a tiny scale model and questionable theory is setting yourself up to get bad data - and bad data is worse than no data at all."

Craig Breedlove shoehorns into Spirit


The Record Run
Black Rock, Nevada, Sunday, October 27th. After four days of rain, the sun once again bakes the surface of the desert. At 1:27 PM, Craig Breedlove takes Spirit of America on a perfect run to 562 miles an hour. The record now seems within easy reach - only eighty miles an hour away. Weather forecasters predict that Monday will bring calm winds and mild temperatures; but satellites also detect winter storms poised to sweep across Nevada. There will be one day, and one day only, to set the record.

At 7:30 AM on Monday morning, an ambulance proceeds across the lake bed without raising dust. It is below zero. Ice crystals sheen the desert surface. Team engineer Walt Sheehan is in a pickup truck with the heater blowing across sheets of graph paper on which he has plotted a curve that predicts Spirit's speed at various distances. He is concerned with such matters as engine thrust and aerodynamic drag, but what most occupies his mind is the car's aerodynamic balance. The team has retained the wing settings that worked at 562 miles an hour, but how will they perform in the transonic zone?

Spirit's first record run is defeated when the afterburner, a device that increases power by injecting fuel into the car's fiery exhaust, does not light. At the east end of the track, The car is turned around. Sheehan increases fuel pressure to coax the burner to function.

At 11:45 AM, as Craig straps into Spirit's cockpit, the radio crackles, a report from the west end of the track: "You have a wind of one five down the course."

Someone says, "does that mean fifteen knots or only one and a half?"

The radio, which has been cutting out all day, remains silent. The wind is still at this end of the track so the crew assumes a knot and a half of head wind. Perfect conditions.

At 11:54 AM, the car explodes down the desert leaving a stream of dust and flame. Entering the flying mile, Spirit strays slightly to the left of the course. Craig corrects. Suddenly, the car swerves right, lifts its right wheel 45 degrees and veers sharply off the track. In the cockpit, Breedlove fights to regain control, battling forces in excess of six Gs - six times the force of gravity. With hands as heavy as lead, he reaches for the fuel cutoff switch.

From the air, a spotter plane radios that the car is out of control, that it's sliding on its side, that Craig appears to be having difficulty shutting down the engine. The pilot watches helplessly as Spirit completes the world's fastest U-turn and heads back the way she had come. He sees Craig deploy Spirit's parachute. This time, it works.

Later, on-board computers revealed that Spirit of America was going 675 miles an hour when Craig lost control. Had she continued on course, Craig would have broken Noble's record.

It's still too early to tell what caused the accident. Perhaps local shock waves, forming on the rear wings, disturbed the car's delicate aerodynamic balance. Some observers saw a puff of dust under the car's rear wings. A pressure reversal may have occurred beneath the car. Craig is certain the after burner produced excessive much thrust which caused him to modulate the throttle. This may have destabilized his rocketing machine. Haste is one certain culprit. With only one day to set the record, the team abandoned its cautious plan of incremental speed increases. And there's one other thing: the wind speed just before Craig launched was fifteen knots - one-five, not one point five. When Craig discovered that particular error he said, "I would never have launched if I'd known that. Wind - that's the most basic taboo of all."

The team has now returned to their base in California to ponder and to rebuild. In the Fall of 1997, they will return, but it's almost certain that this time Spirit will share the desert with a hostile camp. On November 12th, at Al Jafr, Jordan, Thrust SSC achieved a top speed of 331 miles an hour followed by a problem with her rear wheel steering system. Flooding of the desert caused the English team to abort further runs. But according to Noble, Thrust will be ready to directly challenge Spirit of America at Black Rock when the land speed course opens on September 2nd. Always the master of sound bites, he calls it "the world's fastest automobile race."

The photographs that accompany this article were taken at an earlier test run at Bonneville

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