On the Edge: Got a Fast Car

A team will attempt to shatter the world land speed record, with a GPS/GLONASS receiver riding the controls.

photo: GPS/GLONASS

In summer 2010, a team of 44 volunteers will attempt to shatter the world land speed record of 763 miles per hour (2 mph faster than sound) by hitting 800 on the speedometer. To 
ensure that the North American Eagle takes it to the limit efficiently and safely, the team captures performance data from 70 sensors, locked to position, 
velocity, and time coordinates  by an onboard GNSS receiver.

An old Lockheed F-104, a ’60s era Mach II fighter, rescued from a scrap dealer in Maine seemed to have the mark of greatness somehow still on it, amid the fuselage holes and grafitti. A team of volunteers converted the plane into a supersonic car: one expert machined the solid billet aluminum wheels, another rebuilt the General Electric J-79 engine, another devised a magnetic braking system. Over three years, the team replaced 40 percent of the plane’s skin panels, 5,000 rivets, the front suspension, and the steering and hydraulics systems.

The 56-feet-long, 13,000-pound car features Magna Force Lev-X magnetic brakes, a stock engine that outputs 42,500 horsepower, burning 160 gallons of fuel per minute in afterburner mode, and a backup 52,000-hp engine.

At supersonic speeds, anticipating and controlling the car’s reactions to physical stresses become critical. explains Steve Wallace, data-acquisition engineer: “Stuff happens when you get up to the speed of sound. Shock waves affect the aerodynamic balance of the vehicle, and when you’re flying six inches from the ground, aerodynamic unbalance becomes very important.” Wallace and the team must ensure that the car does not burrow into the ground or lift any of its wheels while in motion; either would be detrimental to record-setting and driver safety.

Accelerometers, strain gauges, piezoelectric sensors, inertial gyros, airspeed and air-pressure sensors, and more all generate streams of data, stored on a laptop computer mounted behind the car’s cockpit. Wallace accesses the system in real time via an Ethernet wireless umbrella of routers mounted on 20-foot-tall towers spaced at 2½-mile intervals alongside a 14-mile track at Black Rock Desert, Nevada. After a test run, he downloads the data to his computer, correlates time and location, then exports to a spreadsheet.

GNSS makes speed measurement more reliable and accurate. “We have a lot of sensors, but one sensor I don’t have is for vehicle speed,” he says. “This is a thrust vehicle; the wheels aren’t driven, so realistically, the wheels are never going as fast as the ground. Measuring airspeed is not a bad way of [measuring vehicle speed], but it’s very noisy. The data are all over the place and you have to do a lot of smoothing and averaging. With GNSS, it’s dead nuts — a great way of getting information I need, fast, without looking at accelerometer data. I can’t think of a more valuable tool to understand what’s happening from a sense of motion of the vehicle in general.

“If we had a $10 million budget, we could buy a ground-tracking radar unit like the Air Force uses, but that ain’t gonna happen. We can get just as good data with this as with a $10 million system, so why go any further?”

The project could provide further practical engineering benefits. The team likens this research to that of the 1960s space program, which benefited development of computers, cellular phones, and microwave ovens.

Manufacturers

A dual-frequency Topcon PG-A1 antenna and Euro 160T OEM receiver collect GPS/GLONASS signals at 20 Hz. A Euro 160T mobile control board rides in the car’s electronics bay. A GB-1000 receiver collects static reference data.