Welcome to Mach 1 News, the newsletter produced exclusively for all those of you who want to follow Richard Noble and his team in their quest to make Thrust SSC the first car to travel faster than the speed of sound. This truly is the last of motoring's great frontiers so join with us and follow them as they prepare for history in the making.
Most people would recognise the names of Edmund Hilary and Roger Bannister as history-makers in their respective fields, but who was the second person to climb Everest, or the second man to run a mile in under four minutes ? Their efforts were every bit as admirable as those of Hilary and Bannister - but they weren't the first and so their fate is to stand forever in the shadow of those who were. So it is with the Sound Barrier. Charles 'Chuck' Yeager, was the first man to fly faster than the speed of sound in 1947 and history still awaits the person who can follow in his footsteps on land.
Richard Noble aims to be that man, and as the holder of the existing Land Speed Record at 633.468mph driving his Roll-Royce Avon powered jet-car Thrust 2 across the dried up lake bed of the Black Rock Desert , Nevada in 1983, he is well qualified to do so. The car he will use is a fifty foot long high-tech projectile running on solid aluminium wheels and powered by two Rolls-Royce Spey engines giving 50,000lb of combined thrust. The work of Richard Noble, Ron Ayers and Glynn Bowsher, this radical design features a tubular steel and carbon composite structure with totally unique rear wheel steering and takes rec
The story behind the project that created Thrust SSC really starts back in the days when Thrust 2 was being designed. A talented engineer by the name of John Ackroyd took a basic layout devised by Richard Noble and developed it along a number of themes. Tentative designs for a supersonic car were shelved when it became clear after wind tunnel tests that one of the interim designs, the one that became Thrust 2, had outright record potential in it's own right. In fact, the basic layout very closely resembled that of a car built by Art Arfons called the Green Monster, a car that had held the record itself in the Sixties. Of course, the rest is history, as the team successfully returned the Land Speed Record to Great Britain for the first time since Donald Campbell briefly held it with Bluebird in the early Sixties.
The situation since then has been very akin to that which existed just prior to the Sound Barrier being broken in the air for the first time, when performance had reached a plateau and designers scratched their heads searching for the breakthrough that would allow quantum leaps in performance to be achieved. Plenty of people came forward with ideas, and while others took the plunge and developed existing themes to try to better his record, Richard Noble sat back for a long while before considering what action to take next. In truth, as the existing record holder, there was not much he needed to do until it became clear that the whispers emanating from one or two potential projects on either side of the Atlantic had some real substance to them , substance that would provide exactly the challenge needed to be the first man to go ground level supersonic.
In the USA, five times record holder Craig Breedlove had planned a supersonic rocket car in the Seventies, but problems associated with fuel supply and wheels and tyres had left it at mock-up stage only, until a switch to jet power three years ago finally persuaded corporate America to provide Craig with the funds to build his challenger. The unveiling of Spirit of America - Sonic Arrow, takes place in Detroit almost concurrently with Thrust SSC.
The other challenger is closer to home, and one that is potentially the biggest threat of all since it is the brainchild of Ron Dennis and McLaren International, the company whose Formula 1 team dominated Grand Prix racing for so long securing the talents of such eminent racers as Alain Prost and of course, the late Ayrton Senna. McLaren have been working away in almost total secrecy for over two years, and just before Christmas 1993 they invited journalists to their Woking headquarters to spring a major surprise by unveiling a full size mock-up of their intended supersonic car . The car was designed by a small team headed by Dr Bob Bell, and will be called Maverick, a name that derives from the department set up to develop it, McLaren Advanced Vehicles.
With growing interest in his record, Richard Noble forged an agreement with Castrol to fund a supersonic car research programme. Castrol of course, have been involved in record-breaking since the days of Sir Malcolm Campbell and Sir Henry Segrave in the Twenties and Thirties, and as major sponsors of Thrust 2 are no strangers to the Land Speed Record. After six months hard work, the research showed that the team had a potential winner on it's hands and the green light was given to move ahead with the full-size car.
The result of all their endeavours will soon be there for everyone to see. But getting the car built is only the first step on the road to making history. The real test comes when Richard Noble points it's needle sharp nose towards the Black Rock mountain at the far end of the desert that bears it's name, and lights up the afterburners on Rolls-Royce Spey engines.
THE SOUND BARRIER
When Richard Noble fires up it's mighty Rolls-Royce Spey jet engines and drives Thrust SSC across the Black Rock Desert at speeds in excess of the speed of sound, he will finally break through a barrier which many at the dawn of the jet age believed to be impregnable and one which gave rise to the popular phrase - the Sound Barrier.
Of course we now know, thanks to the efforts of pioneering pilots such as Chuck Yeager in the Bell X-1 rocket aircraft in the late Forties, that strictly speaking there is no such thing as the Sound Barrier, the speed of sound being regularly exceeded since then by a variety of military aircraft and even the odd passenger plane - hands up all those who've flown on Concorde! Nevertheless, it is still true that strange things happen when the flow of air over the surface of an aircraft moves from the transonic to the supersonic region. But do the lessons learnt at high altitude and the rules developed from them apply at ground level? That's what Richard Noble and his project team have to find out.
Problems associated with flying close to the speed of sound first became apparent during the Second World War when aircraft such as the Hawker Typhoon and Republic P-47 Thunderbolt began displaying some alarming characteristics in steep high-speed dives, dives that sometimes resulted in tail assemblies and other parts breaking off as a result of the severe buffeting encountered. Research showed that rather than flowing smoothly over and under the wing at these speeds, the air had a tendency to build up, or compress, ahead of it, sending severe vibrations through the airframe and causing a massive increase in aerodynamic drag. Thus the notion of some sort of invisible Sound Barrier was born, a notion perpetuated in popular films and books of the period.
Imagine trying to force the water from a one inch diameter garden hose turned on at full power into the end of a ¼inch diameter waterpipe and you'll get a graphic illustration of what compressibility means! The water, like the air compressing against a wing, builds up into a cone-shaped shock wave that has nowhere to go except outwards.The aircraft designers and aerodynamicists sought to solve the problem in a number of ways. Higher speeds were achieved by delaying the effects of compressibility, first by the use of swept wings developed by the Germans for their Me262 fighter, and then by the use of much thinner section wings allowing the air to once more pass easily across the surface.
The real breakthrough came with the advent of jet and rocket engines. Until then, only a handful of people had experimented with fairly crude solid fuel rockets attached to modified gliders for short duration flights, while the concept of a piston engine driving a large propellor to drag the aircraft through the air had been developed almost to it's limit. The point about thrust propulsion was that apart from removing the drag of the now redundant propellor, even in it's infancy power outputs equalled those of fully developed piston engines, power outputs quickly pushed up to undreamt of levels by designers keen to exploit this new technology.
All of this theory came to fruition on 14 October 1947 when Captain Charles 'Chuck' Yeager took the bright orange, Bell-X1 research aircraft beyond the speed of sound for the first time. The short, thin wings attached it's bullet-shaped fuselage were propelled through the air by rocket rather than jet power and having built up speeds slowly over successive flights, Yeager finally broke through the Sound Barrier, while those watching on the ground were the first to hear the characteristic sonic boom as the cone-shaped shock wave reflected from the Bell X-1 bounced off the earth's surface.
But just how fast is the speed of sound and what will the Land Speed Record stand at when Thrust SSC and Richard Noble have done their stuff? Well, that's where things get a little tricky. Generally speaking, sound travels at about 1000 feet per second or 761 miles per hour, but this can vary enormously according to air density, which in turn is affected by both temperature and altitude. The higher you go, the thinner and colder the air gets, thus effectively slowing down the speed of sound to anywhere between 620 - 700 miles per hour. Even at a fixed altitude, for instance the track at Black Rock, air density and thus the speed of sound will vary according to ambient temperature. Still with me? Since Thrust SSC will be running on the same track as it's predecessor Thrust 2, calculations based on that car's performance, the likely air temperatures and the height above sea level, indicate that the speed of sound should be around 747 miles per hour. That is definitely not hanging around!
When the sonic boom from the shock wave reflected off Thrust SSC finally resounds across the surface of the Black Rock Desert, Nevada, USA, Richard Noble will be the first man to go ground level supersonic, an achievement that many rate as more challenging than that of Chuck Yeager in the air. As we said, history in the making.
THRUST SSC DESIGN PRINCIPLES
"On the face of it, the World Land Speed Record might seem simple: obtain the most powerful engine available to you, assemble a team of specialists prepared to take career risks, build the smallest practical car, ferry the whole outfit to a remote desert track 6,000 miles from home...and have a go." That was Richard Noble speaking in the foreward to the 1985 book "Land Speed Record" by Cyril Posthumus and David Tremayne, a book that is generally accepted in LSR circles as the definitive textbook on the subject. But as Richard pointed out later on, it isn't quite as simple as that.
Designing any car usually involves compromises of one sort or
another and in that sense, although the rules allow almost unlimited
freedom of choice, record-breakers are no different. As Richard
said in the foreward quoted above, the most powerful engine available
is a good starting point, but what about wheel size and layout,
weight, fuel load, driver location and the surface on which the
completed projectile which take a shot at writing it's name into
the record books? No matter where you start in any of these areas,
an optimum solution for one major aspect of the design usually
leads to a less than perfect solution in at least one of the others.
Such is the lot of record-car designers.
Let's try and follow the thought processes that led to the design that finally emerged as Thrust SSC. And since Richard mentioned engines, then that's as good a place as any to start. From the very earliest days of record-breaking the most affordable and reliable way to secure the abundant power necessary has been to use an aero-engine. Very few engines have been designed specifically for record-breaking since the time in 1910 when Fiat installed a massive 28 litre airship engine in a car and set a trend that continues to this day. When piston-engined, wheel-driven cars gave way to thrust, two distinct camps appeared, those who favoured rockets and those who favoured jets.
In 1970 Gary Gabelich set a rocket-propelled record of 622.407mph in the Blue Flame and ushered in a design concept that many felt pointed the way forward towards the Sound Barrier. The advantages of rockets are enormous in that the engine itself is a model of simplicity and lightness compared to a jet and since it does not need an air-intake to feed it's chemical reaction, the cross sectional area of the car is limited only by the width of the driver's body. Thus the concept of a long needle nosed, lightweight projectile with closely coupled front wheels and outrigged rear wheels was born.
But for all their many benefits, rockets also have enough drawbacks to give any potential LSR aspirant many a sleepless night. For a start their appetite for fuel is gargantuan, which means that most of the given length of the vehicle will comprise fuel tankage. As speeds increase, so more and more fuel is needed, which in turn increases weight, which in turn means that more fuel is needed, which means..........and so on and so on. Another unwelcome by-product of the rocket's fuel thirst is the dramatic change in weight from full to empty in a few seconds, a weight change likely to make a rocket-car more unstable rather than more stable the faster it gets. All of which leads to the inevitable conclusion that jets are an altogether more feasible proposition. After evaluating a number of available options, the team secured four of only twelve Rolls-Royce Spey 205's ever built. A specially developed version of the Spey 202 fitted to the RAF and Navy Phantoms, it fitted the bill perfectly.
With that decision made, the next step was to calculate the sort of power that would be needed to travel ground level supersonic. This is where the first of the trade-offs occurs in that one big engine in order to reduce cross-sectional area would be ideal. However, that means that the driver either has to be located way out in front of the engine or to one side as with Thrust 2. Option one was out not only for reasons of safety, but also because it is very difficult for the driver to sense changes in pitch and yaw sitting that far forward. Option two was also a non-starter this time because it would mean a major increase in cross-sectional area and therefore drag.
The answer when it came was straightforward: follow the maxim of "too much power is just enough" by using two engines and then mount the driver between them. This central driving location in the middle of the car gives good feel for what's going on and if built as a single integral unit with the engines, provides the best possible level of secondary safety for the driver in the event of an incident. Although secondary safety is vital, it is far more important to place the emphasis on primary safety by designing a vehicle that runs straight and true in the first place without any tendency to lift it's nose at speed.
The way this is achieved for Thrust SSC is to locate most of the weight - that is the engines - towards the front of the car and then use a tailplane assemply mounted right at the rear to exert enough aerodynamic drag to pull the car straight if it strays off-line. The combined effects of the centre of gravity towards the front of the vehicle and the aerodynamic drag exerted on the tailplane assemply at the rear, gives the design the same sort of basic stability that ensures that a dart hits the dartboard pointy bit first! The principle is exactly the same.
As is explained elswhere in this newsletter, fixed front wheels on either side of the engine pods give Thrust SSC a stable track, while the offset, tandem, steered rear wheels mounted in the narrow chassis section at the back keep them well out of the way of the engines' exhaust and dispense with the need for any sort of outrigging device on which to mount them.
The final piece of the design jigsaw are the wheels themselves. Hard-won experience gained running Thrust 2 at Bonneville and Black Rock on solid aluminium wheels provided a fund of data that proved invaluable when Glynn Bowsher sat down to pen those to be used this time. I well remember a conversation with Bluebird designer Ken Norris when he explained how easily people forget that total drag is the sum of aerodynamic drag exerted on the vehicle itself and the rolling drag caused by the contact between the wheels and the track surface. In many cases rolling drag can account for 50% of the total drag.
The trick, of course, is to design a wheel that will give sufficient grip to exert control but not dig into the surface enough to incur an unacceptable drag penalty. This a highly complex area not totally governed by the design of the wheel, since the weight of the vehicle itself and the downforce needed to keep it on the ground also tends to push the wheels into the surface. Conversely, at speed, air rushing under the car produces lift and effectively lightens loads causing the wheels to plane across the surface, thus reducing drag - that is if you get it right! As with every other aspect of Thrust SSC the team are confident that they have got it right.
The acid test comes when the big black car runs for the first time, but if the phrase "if it looks right, it is right" ever applied to anything then surely it applies to Thrust SSC, the car that literally should be faster than a speeding bullet.
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