Yesterday was an extraordinary day - everyone was on an incredible high after the SSC reached a peak speed of 624mph on the second run, then just after two o'clock Richard Noble called everyone together in the Aireshelta for an announcement. The Spirit of America team were in financial difficulties - if they remained unresolved, they would have to pull out of the race. Faces in the inflatable hanger were long - we have all been through the mill of money shortages on our project and know what this situation feels like. Indeed, barely a month ago there was serious doubt about whether ThrustSSC would make it to Nevada. No-one wanted the race to end like this - we are here for a competition, and the Spirit of America team are good friends.
Work carried on at the Desert Pits however - last night the main server engine for the Web Site was moved to Digital's Dascombe Road site in Boston, Massachusetts, to enable it to handle the extraordinary load it is now experiencing. The site was copied onto DAT tape in Newbury, England, then flown by Concorde to New York and on to Boston - the current joke is that "the Site has gone supersonic, when will the car?" As well as a cluster of machines now sending you the pages, Digital have installed two "T3" lines - each giving around 44 megabits per second of capacity. As soon the site was loaded onto the new machines we copied in the updates we had made since the tape was cut and put the system live. I admit I had been nervous about making such a move at a peak time - but the Digital people did an extraordinary job of the move, and there was no impact on service whatsoever. The rate of growth of the accesses is currently exponential - and we are now in a very strong position to handle this demand. The change should be completely transparent to you - please continue to access the Web Site in your usual way, and we hope you enjoy it!
Back to record breaking. Today we have two runs planned. Because of the problems with one of the onboard computers yesterday we are repeating the second run. Starting at Mile 1, Andy Green will accelerate to 570mph indicated before throttling back and holding his speed steady through the measured mile. According to Ron's computer predictions, he will stop at Mile 12.
The second run will be rather different. Now that speeds have exceeded Mach 0.8, run profiles will be controlled by Mach number instead of indicated air speed. This can have an interesting effect, because it could lead to us progressing through our run profiles, but running at a lower speed on one run compared to the run before.
Aerodynamicists and aircraft enthusiasts can skip the next few paragraphs, but for the rest of the readers, I'd like to explain about Mach numbers and related speeds. Your Mach number is your speed relative to the speed of sound. Mach 1 is the speed of sound, Mach 2 is twice the speed of sound, and so on. Our second run today will be to Mach 0.85 - 85% of the speed of sound. The speed of sound varies by temperature - not pressure as is often quoted. To be exact, the speed of sound is proportional to the square root of the absolute temperature (and that's as complex as this explanation gets!).
At the speeds we have been running at to date, profiles by air speed have been the right option - the air speed has been the significant factor in ensuring the car is progressing in safe increments. Now, as we approach the speed of sound, the Mach number is the critical figure - as the development and movement of shock waves around the car is dependent on that figure. Hence we will be asking Andy to drive according to the Machmeter, not the ASI.
This means that in particular circumstances, a run at higher Mach number can occur at lower airspeed. For example if one run is at say, Mach 0.95 (we'll use the usual shorthand of M=0.95) in the high temperature air of a Black Rock afternoon, that might give a ground speed of 725mph. If the next run was in the cool air of a Black Rock morning, M=0.96 - higher up the scale - might only be a ground speed of 710mph. We would be moving forward in our development program, but the speeds would not be higher. From a scientific point of view - and ThrustSSC is a research vehicle as well as a World Land Speed Record car - the next few weeks should be very interesting.
I've digressed from today's activities again. It's 0908hrs and ThrustSSC has been rolled out to the start at Mile 1. Roll-out was somewhat delayed: after yesterday's problem with one of the onboard computers, Systems expert Jerry Bliss has been working hard to resolve the problem, with much rewriting of code, and more time was required this morning to ensure that all is well.
After yesterday's problems with low flying and landing light aircraft a NOTAM (Notice To Airmen) has been issued and Jayne is broadcasting a request to stay clear of the desert. The various aircraft in the area are responding well, and one requests the barometric pressure. Jayne obliges, but the British use millibars while the local standard is inches of mercury. Andy taps a few keys on a calculator - and the converted figure is transmitted.
It's hardly worth mentioning, but this is a run day so we have had a problem with one of the Palouste air-starters. Our healthy unit has been mounted on a trailer for the long trips to the north end of the desert to avoid the wheel problems we were experiencing with the long tows. In the meantime arrangements have been made to borrow a unit off the National Air Guard for use on record runs - we can manage with our troublesome second unit for now, but cannot risk problems later on.
At 0914hrs the SSC comes on the air. Andy Green exchanges greetings with Run Controller Jayne Millington in the Pit Station, requesting air temperature and pressure which she provides. At 0925 Jayne checks that everyone is ready while Firechase charges North to take up position opposite the Merlo at Mile 7. Three minutes later Andy reports: "This is SSC, two minutes." Jayne responds: "SSC, copied. All stations, two minutes to roll." Firechase arrives at its alloted location.
SSC requests wind speed. "2 o'clock, variable, 3mph" responds Jayne, looking at the Desert Pits weather station. It's a still morning - dust is hanging in the air and the Merlo's flag hangs limply on its pole.
Finally Andy reports: "SSC ready to roll."
"SSC, you are clear to roll. All stations, SSC is rolling."
The dust begins to rise about the haze at the south end of the desert as ThrustSSC accelerates. The radio barks: "SSC, aborting". It enters the measured mile at high-speed, and passes with its parachute stretched out behind. Firechase and the recovery team roll towards the slowing jet-car as it comes to a stand at Mile 9.5 - there is still a lot of fuel on board.
At 0934 Andy reports that SSC has stopped. Jayne acknowledges and reports that Firechase and Recovery are on their way. Barely a minute later Rob Hemper comes on the radio: "Pit Station, Pit Station. Recovery are at SSC." "Copied. Thanks." "Mobile Recs" requests and receives permission to join the car.
Finally at 0937 the awaited call comes: "Pit Station, SSC. The car is safe." Once again Jayne relays to all stations. Pegasus lands next to us with the Castrol cameraman on board. The pilot, John Fack, informs us that the right-hand (leading) rear-wheel was off the ground from the middle of the measured mile. Inevitably your mind starts to wonder at the cause - even when the suspension bracket failed in Jordan the unladen wheel left a mark.
Nick Dove radios in - there will be no second run. Andy reports that 'Comp 1' had failed again - this time at 500mph at Mile 4.4. Abort had been at Mile 5, reaching a peak speed of 550mph before the engines spooled down. The long tow home begins behind a Supacat, while Jerry starts to analyse the data.
So why only one rear wheel track? 'Comp 1' looks after the active suspension, 'Comp 2' being responsible for the hydraulics and pressure sensors. With the run aborted the two rear suspension struts themselves slowly, the one for the trailing rear wheel slightly ahead of the leading rear wheel's. Andy reported that he was still able to steer the car, and the tracks confirm that the SSC was no more than 2-3 feet off line at any time.
By the time we are back in the Pit Station Jerry has been able to take a good look at his data. Although the run was aborted, he has some excellent results - the car is developing positive downforce and a rear-suspension adjustment that he had suspected would be necessary has been shown to be so. The rear suspension has two distinct positions, one three inched above the other - to date the arms have been mounted in the upper set, they will now be moved to the lower points. The idea of this arrangement is to give a greater range of adjustment than is available in the active suspension if the data from the sensors indicates that a different setting is required.
Next stop is lunch, courtesy of Castrol who have arrived with their caterers, followed quickly by a long photocall. The car is cleaned off and the team gathered for pictures by Alain Ernoult. Possibly the worst one was wearing the Castrol fleece jackets and fleece overalls - in the mid-day Nevada sun!
We will run the car again on Thursday morning. In the intervening four days everyone will have a day off, while the track preparations continue, and the car is attended to. On the engineering side the rear suspension height adjustments will be made, and a problematic power supply will be replaced. The problem line of code in the software has been found and has already been fixed. The opportunity will also be taken to undertake planned chassis checks. People are starting to look tired - so a few mornings without getting up at 4 o'clock will do us all some good...
The competition to break the sound barrier on land is looking up again, too. We understand that Craig Breedlove has succeeded in securing the necessary funds and will be back tomorrow or Monday to resume his running. The timekeepers arrive to set up on Monday - this is getting interesting!
 |
 |
 |
||
| Sponsored by | This site best viewed with Microsoft Internet Explorer 3 | |||
 |
 |
 |
||