Thrust SSC - Mach 1 Club

Frequently Asked Questions

With all of you writing in and asking the team questions, we thought we'd add a section to post the most popular questions and the answers that the team members gave. Please keep the questions coming in - the Team really enjoy receiving and replying to them!

To: Ron Ayers, Thrust SSC's Aerodynamicist

How will you stop it?

By a combination of parachutes and brakes. As Andy backs off the throttle after coming out of the measured mile, the enormous aerodynamic forces will begin to slow the car immediately. In this state, things are pretty unstable, since tons of air that would normally be passing through the engines spill out of the front around the air intakes, so military design parachutes intended for supersonic speeds will be deployed at about 700mph. These will quickly bring the speed down to 400mph at which point the ‘low speed’ parachutes will be deployed. Once Andy sees 200mph on the speedometer, he can then use the carbon fibre brakes designed by Glynne Bowsher to bring things to a halt. If the low speed chutes fail, the carbon discs (derived from a those used on the Boeing 757) can be used for an emergency stop. There are four discs on the front and two on the rear, so plenty of stopping power is on tap.

To: Thrust News

What sort of fuel does it use?

‘Normal’ aviation will be used, although the exact mixture has yet to be determined. Basically kerosene, the fuels are commonly designated as JPA in civil guise or numbers such as JP1 through to JP6 for military use. Thrust carries 300 gallons of the stuff in two 150 gallon tanks mounted immediately behind the cockpit. About 240 gallons will be used on each run - not surprising when you consider that at full power it will be burnt at the rate of 5 gallons a second!

To: Ron Ayers, Thrust SSC's Aerodynamicist

Given the great leap forward for the LSR that Thrust SSC will bring, how much higher do you think the record could go? Also if you had unlimited resources, what would your idea of the ultimate record car be?

The ultimate speed limit is a very interesting question. However, I would point out that when the first record was set in 1898 (I believe the record set was 39.24 mph), any suggestion that 100 mph could be reached would have been dismissed as science fiction. In fact, that so called 'impossible barrier’ was achieved as early as 1904.

We have a habit of defining ultimate limits in terms of our current technology. We forget that technology moves on so the limit is itself pushed back. You can see from this that I believe that there are no absolute speed limits, although attempts to break the record will become ever more infrequent as the cost of mounting the attempts gets more expensive.

With Spey jet engine in Thrust SSC we are pushing to the limits the engine technology that is currently available to us. But the Spey is a 30 year old engine as no-one entrusts LSR teams with expensive and secret, state-of-the-art engines. This suggests that in, say, 2025 the EJ200 engine from the European Fighter Aircraft may be available to us. The EJ200 has a much higher thrust/weight ratio than the Spey and I would estimate that this could give an LSR of 1000 mph.

However, such a speed would depend on other developments. For instance the forged aluminium wheels on Thrust SSC would explode at that speed as the radial acceleration at the rims would be about 50,000g! So we need to find a material with a greater strength/weight ratio than aluminium. Composite materials may not be the answer as they do not normally show good resistance to abrasion - and there would certainly be severe abrasion on a desert at 1000 mph. Wheel bearings and their lubricants would also need to be considered. Despite these problems, I still say that the question is not ‘if’ but 'when'.

To: Thrust News

How much does the car weigh?

Original estimates were somewhere in the region of 7 tons, but it’s clear that the completed vehicle fully laden (ie with fuel and driver) will be around 9 tons. This seems like an enormous increase, but in fact is not that suprising or significant . Bear in mind that this is both the prototype and the actual record vehicle (there is no such thing as a pre-production record-breaker!) so calculating the exact weight beforehand is an almost impossible task.

The design principle is that this is a safe car that goes fast, not the other way around, so given the enormous power of the engines, the build team could err on the side of increased safety where necessary, rather than having to build to an exact weight limit. Power is more than adequate since the twin Speys produce power equivalent to 3 Royal Navy frigates!

Interestingly, Craig Breedlove has experienced the same weight increase situation with his single engined car and although it is lighter than Thrust (about 6 tons), the overall power to weight ratio broadly similar.

To: Thrust News

I thought that a car called the Budweiser Rocket had gone supersonic already?

The rules governing the LSR call for two runs to be made in opposite directions of the same measured mile or kilometre, both runs to take place within one hour. The LSR is the average of both average speeds as recorded using internationally certified timing equipment As described elsewhere on this server, rockets are a viable alternative to jets for high speed attempts but with one major drawback - the amount of fuel that they consume!

In 1979, a team led by Hal Needham provided driver Stan Barrett with a Bill Frederick-designed 3 wheeled rocket car, and announced their intention of breaking the Sound Barrier. Unable to sustain power throughout the measured mile as required by the rules because of fuel thirst, or to refuel the car for a return run within one hour, they elected instead to buck the rules and aim for a peak speed only through a 50 ft timing trap. In fact, even that was ignored, speed instead being calculated by using data from a military ground tracking radar system. After a series of runs, a claimed peak speed of 739.666mph was announced.

There is no doubt that Stan Barrett travelled briefly in excess of 700mph and that he is a very brave man, since photographs taken at top speed clearly show both rear wheels off the ground. Be that as it may, it was not over a measured mile or kilometre, two runs were not made and it did not use accredited timing methods. Peak speed only was the objective and even then, there was no sonic boom.

To: Thrust News

How do I get tickets to see the unveiling of the car?

Right now we're still working out the final details of where and how that will take place, so can't give you the information you need just yet - sorry.

To be honest we hadn't planned on selling tickets, but rather making sure that the launch venue could cater for a special event for Mach 1 Club members. We'll let you know as soon as we can.

We've been holding Open Days for club members throughout the last year, catering for about 400 at a time, and we'll continue to fit these in whenever we can throughout the coming year. As a club member, you can register for a free place on one of those visits, although we cannot guarantee an exact time.

One way to make sure that you see the car on one of its shakedown runs in this country is to join as a Gold card member.

To: Ron Ayers, Thrust SSC's Aerodynamicist

How fast will it accelerate and what g forces will be involved?

Calculations suggest 0-600 in 16seconds and 0-850 in 40 seconds. Pretty stern stuff, but in fact, apart from a brief initial spike that could approach 5g, 3g initial acceleration will be the order of the day, tailing off to about 1g as the car continues accelerating through the measured mile. 1g is about the fiercest level you would expect from the most potent roadgoing vehicle. 5 or 6g negative is expected as the parachutes are deployed to slow down. Fast jet pilots like Andy Green are well used to coping with forces such as these.

To: Andy Green, Thrust SSC's Driver

How you feel about being the driver of the first car designed to break the sound barrier? Do you feel any fear due to the uncertainty of such an attempt, or is it just viewed purely as a challenge?

As you can imagine, I am tremendously excited about the prospect of driving Thrust SSC to a new, supersonic, Land Speed Record. It is very thrilling to be part of the team which will achieve a world first - there aren't many left, and we're going after one of them.

As far as being afraid of the risks goes - no, I am not worried about it. Land Speed Record breaking is not as dangerous as most people think - Britain has held the record for longer than any other nation and only one Briton has ever been killed attempting it (Parry Thomas, in 1927 on Pendine Sands). We have the safest, most stable and best-researched design ever created for the attempt and I would argue that we also have the best team ever assembled for the job, lead by Richard Noble himself, current holder of the LSR, who has been above 600 mph on 11 occasions and makes it sound boring! We have done a great deal of work to ensure that there is none of the uncertainty that you referred to in your question; we're not going into the unknown, only the unexplored - and it's going to be quite a trip.

To: Richard Noble, Director of Thrust SSC

Exactly what do you anticipate the maximum speed of Thrust SSC will be, once all developments and testing have been completed?

The car was designed to break the Sound Barrier, which means achieving an average speed of about 750mph over a measured mile or kilometer. Since the speed of sound varies slightly with altitude and temperature, it's difficult to be precise, but at Black Rock (fixed altitude!) on an average day, we expect the speed of sound to be 747mph.

Two runs must be made within an hour of each other, each in different directions, but over the same measured mile or kilo. The average of the two speeds must beat the existing record by 1% to be ratified.

So, if the average speed is 750mph, then it follows that the peak speed must be much higher and so we have researched all mechanical and aerodynamic design for ThrustSSC up to 850mph. This gives us sufficient leeway to ensure that we clearly exceed Mach 1. It would be extremely upsetting to beat the record but only achieve, say 730mph, and miss our prime goal.

From his aerodynamic research, Ron Ayers believes that the car would work successfully at 1,000mph, but this would need a mass of additional mechanical testing. The loads and pressures on components at this speed are enormous and tend to grow exponentially, so the research needed is daunting. As an example, at 850mph the solid wheels will spin at 8,500rpm and will undergo radial pressures in excess of 35,000g!! Speeds of 1,000mph would almost double that pressure.

At 850mph (Mach 1.1) we believe that there is a great deal of power left and therefore more performance potential. Once we get to 850, provided the additional power is there, then we will research and modify the car for faster speeds.

To: The Thrust SSC Team

Would anyone involved with the project be interested in giving a presentation to a society I am involved with?

We are always interested in giving both public and private 'roadshow' presentations! As well as giving us the opportunity to inform the public about Thrust SSC, such occasions are always very useful for finding what people think of our project.

Editorial note: Please contact the Team via the Internet at if you would be interested in organising a roadshow presentation about Thrust SSC.

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