Back in 1965, Lee Breedlove set the women's land speed record on Utah’s Salt Lake Flats with an average speed of 308.51 mph (496.49 km/h) over four runs. That record stood for 48 years until this month, when Jessi Combs smashed it in her 52,000 hp North American Eagle Supersonic Speed Challenger with a speed of 392.954 mph (632.39 km/h).

On October 9, running out on Oregon’s 13 mile (20.9 km) Alvord Desert course, which is essentially a dried out lake bed, TV celeb Jessi Combs' first pass in the North American Eagle (NAE) Supersonic Speed Challenger delivered a top speed of 371 mph (597 km/h). Rules require racers to complete two passes within a one hour time frame and on the second run using the Eagle’s afterburner to full effect, Combs hit a speed of 440.7 mph (709.25 km/h), producing a record breaking average speed of 392.954 mph (632.39 km/h). The Eagle’s afterburner does provide the pilot a short burst of instant power, essentially doubling output from an already impressive 52,000 hp.

The converted F-104 Lockheed Starfighter that Combs pilots once actually served as a chase plane for both the record breaking X-15 experimental jet and the SR-71 Blackbird. Retaining its original intake ducts but sporting smaller wings to retain speed stability, the NAE racer now weighs in at 13,000 lb (5,896 kg) and measures 56 ft (17.07 m) from nose to tail and just over 7 ft (2.1 m) across at the widest point on the engine intakes.

Propelled by a General Electric LM-1500 Turbojet engine, the NAE crew increased the engine’s stock output by 10,000 hp from the leisurely 42,000 hp used for low speed test runs, up to the current 52,000 hp. But with great power comes great mileage degradation. North American Eagle reports the jet's appetite for fuel at idle to be in the 40 gallons/minute (151 L/min) range, but when under full throttle the Eagle vaporizes out 80 gallons/minute (302.8 L/min). Kick in the afterburner and another 10 gallons (37.8 L) disappears out the Eagle’s oversized, military grade tailpipe every minute.

As the Federation International de Automobile (FIA) is the governing body for land speed records, strict rules regarding engines and wheel configurations had to be followed in order to properly qualify. The FIA rules require the vehicle to be considered a “car” sporting four wheels. So in order for the Eagle to blast across at the lake bed at subsonic speeds, solid billet aluminum wheels were chosen. Solid aluminum wheels not only reduce rolling weight but remove traditional concerns regarding centrifugal forces associated with rubber tires. The solid wheel system also allows the driver to focus on “piloting” the ground based fighter rather than having to drive it.

Inside the cockpit, Comb’s surroundings, like most race cars, are sparse and minimalistic. Instrumentation is limited to engine temperature gauges, fuel and oil pressure gauges and the all important air speed indicator and mach meter. The steering wheel is a joystick, providing tail and rudder control at speeds similar to its airborne brethren. Unlike traditional fighter jets where oxygen is supplied to the pilot, the NAE team went with a simpler system using a scuba diving tank to provide compressed air.

The NAE crew hopes to break the existing land speed record of 761 mph (1,225 km/h) in the Eagle in 2014, this time with team owner Ed Shadle at the stick. In the meantime, Jessi Combs next plans to chase down the existing female speed record of 512 mph (824 km/h) achieved in 1976 by stunt woman Kitty O’Neil in a three-wheeled racer.

Watch Jessi's 440 mph run via the vid link.

Source: Land Speed