Thrust SSC - Engineering

Driving ThrustSSC - The Jordan Experience

by Andy Green, Driver of Thrust SSC

We’ve been back from Jordan for a while now, most of us catching up on the day-jobs, analysing the results of the Jordan runs and preparing the Car for its next desert trip. Now that we’ve had time to think about what we achieved, here are a few thoughts on what it was like driving Thrust SSC in Jordan.

The Climate

ThrustSSC at speed passing 'Fecher' track markers
(ThrustSSC at speed passing 'Fecher' track markers. Photo: Jeremy Davey. Digital camera courtesy of Canon (UK) Ltd)

The Al Jafr desert is in south-eastern Jordan, near the Saudi Arabian border. It is about 2500 feet above sea level and very hot in the Summer (if you want to see how hot, watch the film ‘Lawrence of Arabia’ - Jafr is the desert where Omar Sharif comes riding out of the mirage). Fortunately for us, it starts to cool down in October and although the sun was a problem during the day, the temperature was generally bearable and it was lovely and cool at night. However, if you insist on wearing thick black layers of fire-proof clothing and strapping into a black cockpit in the middle of the afternoon, you rapidly find that you can boil eggs in your underwear (during one of our engine tests, I opened the cockpit between runs and felt a lovely cool rush of air... it was 28 degrees C outside, so you can guess at the temperature inside!).

Andy Green driving the Land-Rover painting lines
(Andy Green driving the Land-Rover painting lines. Photo: Jeremy Davey. Digital camera courtesy of Canon (UK) Ltd)

Marking the Desert

The Jafr desert is flat, featureless and very hard, so marking it was going to present something of a problem. Fortunately the Jordanian Air Force came up with the solution of using quick-lime mixed with water to produce a white, environment-friendly (and cheap!) way of marking lines, which was spread from a very old Land Rover with terrible steering - it was much harder driving the Land Rover in a straight line at 20 mph than it was to follow the line later in the SSC at 320 mph! This gave me a very clear mark to follow - so no excuses if I wasn’t keeping the Car straight.

Driving on the Desert

The first look I would get at the track before each run was from the Jaguar Firechase - this would be driven down the track about half-an-hour before each SSC run to check the track was clear and that nothing had been dropped by the Bedouin trucks which cross the desert at all hours of the day and night. I had 2 reasons for wanting to drive the Jaguar on the track inspection - firstly, it was a good way to remind myself of the features (crossing tracks, etc.) that I would see; secondly, and more importantly, unlike the SSC it is air-conditioned!

The Run Schedule

For each run, there was a detailed run schedule so that we could learn the maximum amount about the Car performance, the systems and the desert. As an example, the first run schedule went something like this:

ThrustSSC's instrument display
(ThrustSSC's instrument display. Photo: Chris Cowell)

Sounds like a lot for one run? Yes - and this is only a list of the highlights - I still had to monitor the engines, suspension and the rest of the systems as well as control the Car while I was doing all of this. Since this was going to use up a fair amount of desert, I also had to make sure that the Car stopped in plenty of time. It proved very difficult for me to judge where I was on the desert, so one of the changes we are making for next time is to have a distance-to-go indicator on the instrument panel... once again, Robert Atkinson has come up trumps with the perfect display and the electronics to drive it. As a temporary measure in Jordan, I had the Firechase positioned 4 miles from the end of the desert and the recovery team at 2 miles to go, each giving a radio call as I passed them.

It was not essential that I remembered all of the numbers since the data system should be recording all of the figures, but the more information I could bring back from each run the better, so that Ron, Glynne and Jeremy could analyse exactly what had happened (and then tell me what I had done wrong, of course!).

Driving the Car

So much for the plan; what was it actually like? The easiest way to answer that is to describe one of the runs and Run 16, the second run we did in Jordan, is a good example. The first run, Run 15, had only achieved two-thirds of the run profile above, because the steering was thrown out of true when the Car hit a crossing track during the run; this was made worse by the hard suspension settings we were trying on the first run. Run 16 gave us a chance to check the figures from the Run 15, to finish off the profile and to try softer suspension settings.

The run itself had been delayed for a gusting cross-wind; I wanted to make sure that it was not going to get any worse. The delay was not unwelcome amongst the team - it gave us a chance to have some lunch! Half-an-hour later, it was run time. After checking the Car externally, I started to strap in while Paul Remfrey fitted the parachute explosive squibs. I completed the rest of the cockpit checks and started the 2 mighty Spey engines - this is very quiet in the insulated cockpit, but deafeningly loud outside. With the engines running and the checks complete, I arm the parachutes and Paul pulls out the chocks with a light-hearted ‘Have fun!’ over the radio. A final check of the cross-wind at the Pit Station, 4 miles away in the middle of the track, and then Jayne gives me permission to roll:

Left foot off the brake, then ease the right pedal gently down to start the Car rolling, accelerating slowly to avoid sucking too much desert dust and debris into the engines (although we don’t have to worry too much - the Spey is a very tough engine). I put in a couple of gentle steering inputs to check the steering response on the desert, after the last set of adjustments, and comment on the video that the steering feels heavier at slow speed.

At about this time, several of the hydraulic warnings came on, together with the audio alarm to tell me there was a problem. I had to answer several questions: How serious was the problem? Did I have to abort the run for the failure? If not, could I continue the run with the remaining systems? Was there anything I could do to rectify the problem? I cancel the alarm with my left hand and immediately look at the hydraulic pressure gauge, which was down at 1000 psi instead of the usual 2000 psi - this was the reason for the warning. Was the pressure falling or rising? (if it was falling, it could be a leak and I would have to abort immediately). As I look, it starts to recover again and at the same time, over the roar of the engines, I hear the sound of the engine hydraulic pump cavitating - air in the hydraulic system. I comment on the video ‘Hydraulic warnings - ignoring them’ and then, as the system pressure was now back up to 2000 psi, I switch on the electric pump as a back-up to the engine pump. We reviewed the video later: total time since the warning first came on was just over 3 seconds. Not bad, but I’ll have to be quicker than that for the very high-speed runs.

As the Car approaches 80 mph, I increase the power to achieve the desired 95% engine rpm (about half of the maximum engine power) and let the Car accelerate up to 220 mph. The surge of power as the engines reach 95% is amazing - and this is only half of what it can do! 220 mph arrives very quickly and I throttle the engines back to idle to measure the deceleration drag at 200 mph (about -0.1 ‘g’ in the cockpit; we get a much more accurate reading later from the on-board recorders). Then on with the brakes, using my left foot - the right stays on the throttle pedal in case I need to shut the engines down in a hurry. Braking gently at first (I don’t want to lock the wheels this early!) to slow the Car down to around 160 mph, I watch the brake temperature rise towards 400 degrees C - barely warm for carbon discs!

The second part of the acceleration is up to 320 mph using maximum dry power - known as military or ‘mil’ power. This is about 60% of the Car’s total power - but it still feels impressive! Rapidly I’m up to over 300 mph, which is slow for a Car like this... but a lot faster than I’ve ever driven before. Again selecting idle, I measure the deceleration at 300 mph, which is a lot more than at 200 - from this run and the previous run, Ron now has the drag at 100, 200 and 300 mph so he can get to work on predicting performance figures for future runs, and the all-important safe stopping distances in case we have a problem. Now time to get some more brake information for Glynne. I put the brakes on more firmly this time, watching the temperatures carefully. Two seconds later the ‘WB TEMP’ (Wheel Bearing Temperature) caption comes on - an indication of a warm wheel bearing somewhere on the Car. I am certain that this is because of heat from the brakes, but don’t take any chances. Cancelling the audio warning with my left hand, I stop braking and then put my left hand back on the steering wheel to deploy one of the parachutes. Sure enough, we later find out that there is no problem with the bearings and that we just had the temperature warnings set slightly too sensitive - which is fine by me, that’s the safe way to do it.

The chute deploys very crisply - it’s out in less than 2 seconds, just as the Firechase crew call ‘Four miles to go’ which means I have plenty of room to stop. We are using the ‘triple’ chutes - 3 high-speed chutes linked together - for these low-speed development runs, and they are very effective, quickly bringing me to a stop, still with almost no effect from the cross-wind... I don’t know what I was worried about, this Car is as solid as a rock! As I slow down I am getting another audio warning intermittently - it is an ‘OIL’ caption, warning of low oil pressure on one of the engines. Watching the caption closely as the Car slows, I think it is a loose wire on the warning system for the right engine (and sure enough, that’s what we find later on that day). Once I’m happy, I shut the engines down (they’ve had long enough to cool, which is good for them) and let the Car roll to a stop.

‘SSC stopped’ goes out over the radio, relayed by Jayne to the rest of the team - they can all relax now, the Car has successfully completed another run. The fire and recovery crews surround the Car and the work starts again for the next run. I start writing down everything that happened - later I will write a run report to let all of the team know what went on.

After I’ve made sure that all of the Car’s systems are safe and switched everything off, I get out and go to find the Firechase - they carry a stock of cold drinks and I need one! Then it’s time for the hardest part of the day - the press conference. A swarm of reporters and cameramen descend on the Car, finally breaking free from Richard who has been doing a wonderful job of controlling them up to now, all wanting to ask their question first: How fast did you go? How did it feel? How fast will you go tomorrow?... and so on. I explain this was a very successful run, achieving all that we wanted to test the Car at this stage. They can’t understand why we won’t go for the record tomorrow, or at the very least the day after!

ThrustSSC at speed on Run 16
(ThrustSSC at speed on Run 16. Photo: Jeremy Davey. Digital camera courtesy of Canon (UK) Ltd)

So what did we achieve on that run? A new fastest speed for the SSC, 320 mph on the cockpit gauge, which measures air-speed: that equated to 331 mph across the ground. A few minor warnings during the run, which were all easily fixed, and a lot of new data on the Car’s performance and its systems, all of which makes it safer to run next time. Most importantly we’ve shown the world that Thrust SSC, the most powerful Car in the world, is one step nearer to the ultimate land speed record - Mach One!

What Next?

The Car is now undergoing modifications at Farnborough - we are using all that data we collected to improve an already excellent Car still further. We’ll be back on the runway testing the changes in a few weeks, then it’s back to Jordan for some serious speed. In the meantime we’re also going to paint the Car - yes, finally it will be all black - and take it to the Tomorrow’s World Live exhibition at the NEC (19-23 March - come along and say hello). In September we’ll be in the Black Rock Desert, Nevada, where Richard set the current 633 mph record (which is the second-longest standing Land Speed Record in history!), to go for the sound barrier - after all, it’s not called SSC for nothing!

Andy Green, February 1997

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