Converting a Mach 2 jet fighter into the fastest car in the world is not as easy as it sounds.
When experienced racer Ed Shadle and aircraft plant manager Keith Zanghi caught wind of a junked F-104 Starfighter airframe and fuselage sitting in an aircraft dealer's hangar in Maine, the idea of breaking the world land speed record seemed a no-brainer. They'd just take the wingless 1950's fighter, slap a simple but reliable five-wheel suspension under it, and then find and install a version of the aircraft's original jet engine. After all, the airframe and skin, as well as the engine, were designed for Mach 2.2.
How hard could it be to top 763 mph (Mach 1.02)? Eight years and at least $300,000 later, the two are still working out the kinks in their Spanaway, Wash., shop (landspeed.com). But they're confident their efforts and those of their all-volunteer crew will soon pay off. So, after more then two decades of the Brits holding the world land speed record, the title will return to North America.
FROM FIGHTER TO RACER
Shadle and his team started off with a real bargain: A proven supersonic frame and aerodynamic body that took millions to develop and build, but only cost them $25,000, plus $3,000 shipping. The F-104, originally designed by Kelly Johnson at Lockheed, was the first plane to fly Mach 2. An F-104 also set the world speed record of 1,404.19 mph in 1958. Coincidentally, the airframe Shadle purchased (tail number 56-0763) did duty as a NASA chase plane on the X-15 project in the mid-1960s.
The team repaired and modified the damaged fuselage, filling and blending the wing roots into the fuselage, and adding a horizontal stabilizer. They also painted and rewired it, installed new hydraulics and a suspension and steering system, and added several devices that will slow the car after its nearly 800-mph run.
The most important component they had to install was the engine, an LM-1500. Fortunately, S&S Turbine Services Ltd., St. John, B.C., was able to supply the team with two such engines. They use a stock engine for test runs and have a souped-up version for the run at the record, and both now have functional afterburners. Getting one of these engines in and out of the Eagle is relatively simple because the airframe was designed for it.
The LM-1500 is the industrial gas-turbine version of General Electric's J79, the engine originally used in F-104s, as well as F-4 Phantoms and B-58 Hustlers. The 17-ft-long, 3,600-lb LM version, however, is most often used in the gas industry to pump natural gas. It generates about 18,200 lb of thrust or 42,5000 hp when using an afterburner.
The engine is based on a single-shaft design with variable-incidence stator blades in the high-pressure compressor stages. The blades are linked mechanically and controlled by the fuel pump. They change angle and the amount of air they move so the compressor does not pull in too much air and over-heat the rear stages of the engine.
"Once we get the blades dialed in and adjusted, they're no problem," says Robin Sipes, owner of S&S Turbines and a vital member of the Eagle team. "But you have to be dead-on with the adjustment or they give you trouble. If they aren't operating properly, the engine is not at peak efficiency."
"And when you bring up the rpms, the combination of the air-inlet design and variable blades sends weird howling noises out of the engine," says Shadle. "It's kind of strange, but sexy, too."
For the enhanced engine, Shadle and his team resized the fuel nozzles and coated them, along with several other internal components, with zirconium. The coating keeps the fuel cooler and more condensed, so they can run more fuel through the engine and boost power by about 15%. The combustors were also changed out for low-smoke, high-output versions found on J79s.
The team doesn't use engine bleed air and only one of two mounting points for hydraulic pumps. Hydraulics power the steering, brakes, and several other systems. A battery driven electric pump provides backup hydraulics.
General Electric, the company that made the engine, has been less than helpful. "They never tested the engine for an application like ours so they don't officially approve of what we're doing," says Shadle. "They even refused to sell us technical manuals because they contend we are not using the engine for its intended purpose. We have to prowl the junk-yards and mobilize our network of contacts for parts and information. This makes parts hard to get and expensive if you can find them. A hydraulic pump, for example, goes for $9,500. So the whole team is really a bunch of scroungers."
The engine burns Jet A or kerosene, and will likely use it for the record run. But liquefied natural gas might be used instead. Right now, the souped-up engine burns about 25 gpm during idle, 80 gpm at max power, and 180 gpm at max with the afterburner. During testing, the car has been fueled with about 380 gallons of Jet A.
"We'd like to load up with just the fuel needed for one run," says Shadle. "That way, I won't have to worry about a couple hundred gallons of fuel slamming to the front of the tank when I slow down. We have to make two runs in opposite directions to get our efforts certified, so we could use the 1-hr turnaround allowed between runs to refuel."
Shadle says he will not use the afterburner to get the car rolling. But once the car hits 200 mph, he will likely use if for the extra boost. Even without the afterburner, the Eagle should take off at 2.5 gs. And with the afterburner switched on, acceleration should climb to 4 gs, rocketing the car to 800 mph in about 4 miles. If more power is needed, or if a suitable surface that long is unavailable, the team is considering adding a small rocket engine, similar to a jet-assist take-off unit (JATO) capable of putting out another 8,000 lb of thrust for a short time.
In test runs with the stock engine on a 5,000-ft runway, the Eagle has hit 310 mph.
WHEELS AND SUSPENSION
To make the jet fighter into a car, Shadle and his team added a suspension in the back. They built and installed a spacer plate sandwiched between the tail-cone and fuselage. It is the main weight bearing point and all rear suspension parts attach to it. The rear wheels just turn freely, so the suspension is relatively simple. Struts run from the main landing gear bay to the hard-point then to the axle. "But we found we were stressing the struts quite hard, so I shortened them to 28 in., and they seem to work better. The suspension actually got simpler as we moved along."
Up front, Shadle took out all the hardware from the front-landing-gear bay. He also took out the stringers, the metal reinforcements usually under the skin, and reattached them on the outside of the skin. This left him clean surfaces for mounting his steerable front wheel. The front wheel uses a trailing axle configuration; a large, nitrogen-filled shock absorber and two hydraulic actuators provide steering. "Depending on how I move the stick, the wheel can move 2.5° left or right."
The Federation Internationale De L'auto-mobile (FIA), the French organization that certifies international automotive speed records, mandates that cars have four wheels on the ground. So Shadle added another stubby axle and two wheels directly under the keel midway between the front and rear wheels.
The FIA also requires that cars have steering on two wheels. "Well I have steering on three," says Shadle. "The front wheel provides most steering, but I can apply brakes to the rear tires individually. So if I want to make a hard right turn, for example, I apply brakes to the right rear tire."
"The whole suspension is adjustable from the driver's seat, so I can add weight to the front to improve steering, and raise or lower the front end as well," notes Shadle.
For test runs under 350 mph, the Eagle team managed to scrounge up some old Starfighter wheels and F-15 tires. A Starfighter wheel is used up front with custom made wheels by Kodiak Motor-sports and Eagle Machine, Abbotsford, Canada, on the rear. "I'm not sure exactly where the mid wheels came from, but they are 22 ply and rated to 239 knots," says Shadle.
For high-speed runs, the team constructed 200-lb wheels machined from solid billets of aluminum. They won't use tires. The wheels can be easily damaged and have a tendency to damage surfaces they're driven over, including salt flats like those in Bonneville, Utah. "The Bureau of Land Management doesn't like those grooves, even though they disap-pear with the next rain," says Shadle. "That's like worrying about ski tracks in the snow."
Running aluminum wheels on salt flats would also send crippling vibrations through the airframe. That's why the Eagle team plans on setting the land speed record at Black Rock Desert in Nevada or Edwards Air Force base in California. In either place, they would be running on a dry lakebed. "Both places are extremely flat and smooth, and the ground has a little give or cushion," says Shadle.
The Eagle team has reservations about the aluminum wheels. "Our FE analyst says the wheels should hold together at 800 mph, but only for a few passes," says Shadle. "That's not good. It doesn't give us much of a safety margin. And we think they will distort at high speeds."
Shadle's major criticism of the wheels is that they are too conical. "I want them flatter, with the mass more centered." So there's a good chance the team will have to spend another $20,000 for a set of improved wheels.
TIME TO STOP
Another critical aspect of a safe run at the record is bringing the Eagle to a controlled stop from 800 mph. The team has a layered approach to handle that. The first step will be deploying the speed brakes built into the Starfighter. Two 4.88-sq-ft panels extend out from the fuselage, creating drag and slowing the car. This shouldn't overstress the speed brakes since they were designed to extend when the jet was flying Mach 1.8.
Next comes the parachute. It, or they, attach to the arresting-hook mounting point, another piece of original equipment on the F-104 airframe. Each parachute gets packed in a deployment bag and shot out of a mortar at the appropriate time. When it reaches the end of the line, the bag strips away, letting the parachute stretch out. "But it can't open until the reefing linecutters cut the lines, which controls the chutes' opening and ensures a good blossoming," notes Shadle.
The team has a 15-ft-diameter low-speed parachute for runs under 350 mph. It's the same as that used on a Northrup F-5 jet fighter. For runs up to 400 mph, the team will use a pair of 16-ft parachutes, like those used on the SR-71. And for the record run, they have several 8.75-ft chute rated to 900 mph and designed for missile recoveries.
Of course ratings aren't always honest. "Our Kevlar reefing lines for the parachutes are rated for 80,000 lb pull force, but in tests, we couldn't get them to hold together past 60,000 lb," says Shadle. "So we'll design and use the parachutes so that they won't generate more than 60,000 lb."
The next braking method relies on rare-earth magnets. Two discs, one for each rear wheel and each carrying four strong magnets, slide laterally on a spline shaft on the rear axle. An aluminum rotor is bolted to the inside of both rear wheels. To help stop the Eagle, the discs are moved outward toward the spinning wheel and rotor. This creates eddy forces in the rotor, which try to stop the rotors and wheels from spinning. It also generates heat and electricity. The rotor absorbs the heat, possibly melting, without harming the wheel. "When the magnets are within 0.125 in. of the rotor, we get about a 98% lock up," explains Shadle. "But if we back them off to 3 in. away, there's no braking at all."
If the magnets create too much heat, a valve opens and water is sprayed on the rotor.
Finally, the front wheel has the original F-104 disc brakes. "But applying the brake too early could disable my steering. So I probably won't use it above 300 mph," says Shadle.
Currently, the NAE team plans on making more test runs at Edwards this October to iron out the kinks and evaluate various components and systems, then going for a record in the fall of next year.