Thrust SSC - Supersonic Race Update

Issue 130 Lead Article - 5th June 1997

Homeward Bound

by Jeremy Davey, ThrustSSC Webmaster and Satellite Communications Manager

Exercise: Jordan2
Objective: Prove ThrustSSC to 600mph on the Jafr Desert
Timescales: Return to the UK as soon as humanly possible to maximise the time available for raising funds to go to Black Rock


ThrustSSC charges across the Jafr at 540mph
(ThrustSSC charges across the Jafr at 540mph. Photo: Jeremy Davey. Image taken with a Fujifilm DS-515A Digital Card Camera)

Yesterday was a most exceptional day for ThrustSSC - before most of our fellow Britons had even had their morning showers, it had stormed across the Jafr Desert in Jordan at some 540mph. The sight was truly awesome - I have never seen a World Land Speed Record car at such speeds before, yet ThrustSSC looked entirely at home as it charged single-mindedly across the sun-baked mudflats.

There was no doubt that Andy Green had done an exceptional job - he is learning all the time about the handling of the car as it achieves ever increasing speeds, and today was a testament to his exceptional abilities. Towards the end of the run as the car slowed first on parachute, then on brakes as the parachute's effect lessened, he noticed that the steering was more difficult than usual. Not so much as to be overly concerning, but noticeable as he kept the car within 10 feet of the white line marking his course.


Back in the Aireshelta for checking
(Back in the Aireshelta for checking. Photo: Jeremy Davey. Image taken with a Fujifilm DS-515A Digital Card Camera)

The first indication of a problem came when the recovery team tried to jack up the rear end on its tow-dolly to return it to the Aireshelta. The jack would not fit underneath - had the active suspension gone wrong and left the rear of the car lower than it should be?

Back at the Pit Station everything seemed good, and the onboard video cameras had achieved good footage, albeit with a couple of unfortunate failures. As the Design Team met to go over the results of the run, it was jovially suggested to Adam Northcote-Wright that he should start rectification work immediately if he was to be ready for the next days runs. I wrote my piece for the Internet, slotted in some nice pictures from the Fuji Digital Camera (beats developing, printing and scanning any day) and transferred it from the development server to the live Web Site.


The failed bracket from below
(The failed bracket from below. Photo: Jeremy Davey. Image taken with a Fujifilm DS-515A Digital Card Camera)

Then came a bombshell. The rear suspension had been damaged during the run. The car was examined carefully and the data logs studied, and the story became clear. It was all summarised in one of Jerry Bliss' graphs showing the suspension loads against distance. Everything was fine until the peak of 540mph when a bracket taking the load from the hydraulic ram on the leading rear wheel gave way. Effectively that wheel was no longer taking any of the car's weight. The active suspension's computers immediately compensated - fully extending the ram and taking all the load on the trailing rear wheel, and as Andy decelerated it held on for five seconds before the load cell between the ram and the hub gave way.


The trailing wheel hydraulic ram (left) and ride height sensor
(The trailing wheel hydraulic ram (left) and ride height sensor. Photo: Jeremy Davey. Image taken with a Fujifilm DS-515A Digital Card Camera)

With nothing to take any load on the trailing rear wheel at all, it was simply along for the ride- a fact borne out by the tracks on the desert. The already damaged support bracket of the leading wheel took over the load as ThrustSSC slowed to a stand. Such was the cause of Andy Green's difficulties and the reason the rear end of the car had ended up lower than it should.


The failed bracket from above
(The failed bracket from above. Photo: Jeremy Davey. Image taken with a Fujifilm DS-515A Digital Card Camera)

So why did the bracket fail? We know the Jafr Desert is much harder and rather bumpier than the car was designed for - Black Rock averages around 9 on the California Bearing Ratio scale, Jafr is off the gauge. Throughout the design of ThrustSSC Glynne Bowsher has always, when in doubt, erred on the side of caution. Indeed, to quote him yesterday evening: "Thank goodness it's built like a tank!" The battering of the higher speed runs and repeated blows as the car jumped over humps and troughs finally got the better of the fitting.


The bent ride height sensor on the leading rear wheel
(The bent ride height sensor on the leading rear wheel. Photo: Jeremy Davey. Image taken with a Fujifilm DS-515A Digital Card Camera)

The upside is that the frame of the car is unharmed, and the number of miles it achieved with the bracket collapsed amply demonstrates the incredible stability and failsafe design of the vehicle. The downside is that the rectification work required cannot be completed in a few days. It is clear to the Design Tteam that we have gone as fast as is safe on the Jafr course - higher speeds on the hard, bumpy surface would inflict further damage.


The rear wheels supported by jacks while the problem is investigated
(The rear wheels supported by jacks while the problem is investigated. Photo: Jeremy Davey. Image taken with a Fujifilm DS-515A Digital Card Camera)

The decision also must take into account the intense heat in Jordan. It is getting hotter by the day, and even a week's delay would mean that ThrustSSC would have to be run ever closed to dawn. The very real possibility exists that by the time the repairs are completed, it will not cool down enough to allow running of the car.


Jeremy Bliss explains the sequence of events to the team
(Jeremy Bliss explains the sequence of events to the team. Photo: Jeremy Davey. Image taken with a Fujifilm DS-515A Digital Card Camera)

The team are saddened by the abrupt end to what had seemed a never-ending series of successes, but yesterday evening's team meeting was remarkably upbeat. We have had problems before, and no doubt there will be many to follow, but everyone is fully aware of the incredible achievement of making nine runs in just thirteen days. The evening was spent partying until the early hours (yes, my head does hurt) and making sure that everyone has the requisite team haircut...

Jordan2 has produced an excellent result - as many of the team as possible will now head back to the UK as soon as possible so that they can prepare for Black Rock. There is huge confidence in the car now - confidence that will be crucial as we raise the funds for this September's head to head against the Spirit of America team.





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