In 1983, Richard Noble drove Thrust2 at 1019.465 kilometres per hour (633.466 miles per hour) across the Black Rock desert in Nevada,
USA, to become the current World Land Speed Record holder. Richard has now assembled a team to design and build a new car to break both
his own record and the sound barrier. The result, ThrustSSC, is powered by two Rolls-Royce Spey 205 jet engines and will have a top speed
of greater than 850 mph or Mach 1.15.
NPL’s Force Section has provided the Thrust SSC team with assistance in the monitoring of several forces within the car. Two of the most critical forces to be monitored are the suspension down-force and the engine thrust.
Analysis of data recorded during the runs of Thrust 2 revealed that, had the car been driven 7 mph faster, its nose would have lifted causing a fatal crash. In order to keep the car on the fine line between ‘flying’ and ‘mining’ over subsonic, transonic, and supersonic speeds, instrumented links are now incorporated in the front suspension. The outputs from these NPL designed force transducers are fed to an active control system which adjusts the car’s pitch so as to maintain a constant down-force.
For the driver to be able to steer the car in a straight line, the thrusts of the two engines must be equal. It is therefore necessary to make accurate in-car measurements of the thrust developed by each engine. NPL created a Finite Element Analysis model of the ex-Phantom jet fighter engine mounts. This was used to determine the most effective position for the bonding of strain gauges so as to measure the load applied to the mounts.
NPL is also currently investigating the problems involved in measuring the speed of Thrust SSC as it travels over the measured mile. Precise measurements of distance and time interval are required. Optical methods are susceptiable to changes in refraction index of the atmosphere induced by humidity and pressure variations - obviously a large pressure wave will be generated as Thrust SSC breaks the sound barrier.
More details about the NPL can be found at http://www.npl.co.uk
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