The ThrustSSC objective for today was to achieve the first ever supersonic FIA World Land Speed Record with two independently audited supersonic passes over the measured mile within the mandatory 60 minute period. The runs were to be numbers 61 and 62 and the timekeeping is by the United States Auto Club under FIA approval.
If successful this would achieve a World First in terms of an authoritative and independently audited supersonic speed.
Previously on Run 59 (7th October) driver Andy Green and ThrustSSC had peaked at an unofficial speed of Mach 0.98 (98% of the speed of sound).
Run 61 started at the South end of the 13 mile track heading North. The car entered the measured mile at 11:22:27 and the following speeds were achieved:
At the mid point of the track the watching press and television journalists reported a sonic boom. The USAC Timekeepers announced a Mach No of 0.996. During the turnaround procedure which involves reloading the brake parachutes, refuelling the car and inspection, it was found that an LVDT (linear variable displacement transformer) had been damaged. This was replaced in situ - but the time taken lost the opportunity for a new World Record.
By this time ThrustSSC was on the Black Rock desert track and encroaching into the Spirit of America's allocated slot. Very generously the SoA team offered to give up their right in order to allow ThrustSSC a chance at the supersonic record.
Run 62 was started at the North end running South. During the acceleration phase the port afterburner failed to light and the afterburner ignition sequence of both engines had to be recycled losing 0.5 mile in acceleration distance. The car entered the measured mile at 14:03:43 and the following speeds were achieved:
|Mach No (mile)||1.007|
Witnesses reported clear and distinct booms - and one of the teams Pegasus microlight desert surveillance aircraft flying near to the track reported a supersonic crack like a shotgun and a substantial vertical disturbance as the aircraft was hit by the shockwave.
During the deceleration phase driver Andy Green reported a double brake parachute failure, which meant that the car would overrun the South end of the track. In fact the overrun was only 1 mile - and working against the clock, the turnaround team Team 2 managed to recover and reposition the car ready for the return run. The parachute failure was caused by damage to the nylon attachment strop due to burning from the cars 40ft afterburner flames.
The profile of Run 63 was identical to Run 62 and despite the delays caused by the overrun ThrustSSC entered the measured distance at 15:04:28 and achieved the following speeds:
|Mach No (mile)||1.000|
Again the shockwaves and sonic booms were reported by witnesses both at the measured distance and also on the surrounding hills. Due to time lost in repositioning the team failed to gain the first true supersonic FIA Land Speed Record by just 49.479seconds.
Andy Green commented: "The Car becomes unstable at around Mach 0.85 as the airflow starts to go supersonic underneath the vehicle and requires very rapid, precise steering inputs to keep it on the white guide line. The Car becomes slightly more stable above Mach 0.9 and can then be steered fairly accurately through the measured mile. For the first time to-day, the shockwaves formed visible moisture on the front of the Car, which could be seen from the cockpit and which moved back along the body as the Car accelerated. The Car then remains reasonably stable as it accelerates through Mach 1, with the rate of acceleration dropping off as the vehicle generates the huge shockwaves which cause the sonic boom. At the end of the measured mile the power is reduced and the Car slows down at over 20mph per second; the Car is again unstable at Mach 0.85 (around 600 mph) as it slows. The chute is deployed at around 550mph, quickly reducing the speed to below 300mph when the drive is effectively over and I can relax and enjoy the view before shutting down the engines and using the brakes to stop next to the recovery crew."
Operations Manager Adam Northcote-Wright stated: "You can make a record any day-but you can only make history once."
Following the success of the days two supersonic runs, the ThrustSSC design team will meet tomorrow (14th) morning to review the data and the results of the inspection of the ThrustSSC car. Provided they are confident about condition, performance and risk the intention is to run ThrustSSC again to achieve the first FIA supersonic record, possibly within the next 24-48 hours. The weather conditions are typical of a high pressure system and the good weather can be expected to continue for the next 2-3 days.
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