'I was recently looking at the old visitors' book from the original Thrust 2 stand at Motorfair back in 1977,' said Richard Noble, the prime mover behind the Castrol-sponsored Thrust SSC challenge for a supersonic land speed record. 'And somebody had written: "Why aren't you using rear wheel steering?" And I thought, "That was probably some madman!"'
Yet Noble's dramatic new projectile will have precisely that: rear wheel steering. And Glynne Bowsher, the man who conceived the idea, is very sane.
Rear wheels mounted in tandem is not new in record breaking. They were tried with great success in the early Sixties in an unusual front-wheel drive car, Pollywog, designed and built by Bob and Bill Summers, who would later break the wheeldriven land speed record with their quadruple-engined car Goldenrod. But Thrust SSC breaks completely new ground by steering with them.
When you think of how forklift or dumper trucks behave, even at low speed, it's easy to appreciate why this bizarre concept has caused many raised eyebrows in the automotive world, and why even Noble himself was a little taken aback when it was first suggested. But Bowsher, the quietspoken Welshman behind the idea, is adament that it is the right way to go, and puts forward some highly convincing arguments.
'The fundamental problem is that if you put the wheels at the front of SSC, you simply haven't got the room to steer them because they are tucked into the nacelles which house the engines and, even more importantly shape their air intakes. You get a big problem with the space for the intakes, the suspension and the steering. You could increase the diameter of the nacelles, of course, but if you do that you are going to increase the drag factor enormously which will naturally affect the maximum speed.
'The only answer was rear-wheel steering, which also solves potentially severe problems with the front wheel bearing arrangement and the provision of adequate brakes.'
The idea had many factors in its favour, but perhaps the most chilling was another negative for the conventional alternative that Bowsher describes in his understated manner. 'All steered wheels on a vehicle are effectively gyroscopes, and though the effect on a road car may be small, on SSC the turning effect at maximum speed would generate forces large enough to threaten to overturn the car. Steering from the rear eliminates this risk, because the wheels have lower inertia and lower forces acting on them.'
Following a feasibility study carried out at Leeds University, Bowsher commandeered a relative's Mini and converted it to rear-wheel steering, and after tests at the Motor Industry Research Assocation's grounds Noble and, later, SSC pilot Andy Green, became convinced they were on to a winner.
Bowsher is a veteran of record breaking, although his previous involvement has centred more on trying to put a stop to high speed. His role with Noble's record-setting Thrust 2 was to design and oversee the construction of Lucas-Girling disc brakes capable of bringing a four tonne car to a halt from speeds as high as 200mph (322kmh), without melting themselves through the massive amount of heat generated.
He succeeded admirably in this task, and in 1982, the year before Noble broke the record, his brakes had an unscheduled emergency test. This came during the final runs at RAF Greenham Common in June, just before Thrust 2 was due to be sent out to Nevada, when Noble kept the power on a fraction too long and ran out of runway as his low-speed parachute failed immediately as he deployed it. He had to slam on the brakes at 300mph (482kmh) and keep the wheels locked at 140 (225) as his only hope of stopping in time. All four of the tyres used during such low-speed runs were shredded to the canvas, but though the brake discs and pads showed signs of an enormous excessive workload, they continued to work perfectly when tested later.
'Glynne is so quiet you can almost overlook him at times,' Noble once said, 'but he really did do one hell of a job with Thrust 2!'
This time Bowsher has played a far greater role in the design of Thrust SSC, though one would be hard pressed to discover this from him. Bowsher continues to keep himself firmly in the background, far preferring the position of backroom boffin to front-of-stage orator. Once Noble and aerodynamicist Ron Ayers had formulated their concept and put it through its initial tests to verify shape and stability, and once Castrol had provided the seed capital that was so crucial in helping things to proceed, there came the moment when Noble needed somebody to do the detail design. With Thrust 2 Bowsher had done his work quietly, and spent his spare time drooling over his other great love, the huge trains that ran freight across the vast American deserts.
'But did you ever see his reports?' Noble said. 'They were the most superb reports, very, very concise.'
Now Noble called Bowsher at home near Birmingham, England, to see if he would be interested in designing wheels that could carry a seven tonne car travelling at 850mph (1368kmh). Bowsher quickly produced drawings for the solid metal wheels that were wider and bigger than Thrust 2's, but on which the stresses had been halved.
At this time he also became involved with designing the backbone spaceframe chassis, on the outside of which the two Rolls-Royce Spey engines are hung. Noble, who hadn't quite expected such versatility, was both surprised and delighted.
'Glynne is incredibly capable, I think the thing with Thrust 2 was that he tended to stay in the background and did his brakes, because that was his area. But he's just taken this thing, and it's absolutely staggering what he has achieved.'
Having thrown his hands up in horror when Bowsher first suggested rear wheel steering, Noble now believes it is the only answer for keeping Thrust SSC on course at at 850mph (1368kmh).
'You know I really do prefer it. It's very, very accurate on the modified Mini that we tested, and you can position the car absolutely on line and hold it there the whole way round a track. I said to him: "Glynne, you're a genius! It really works!"'
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