I like to dig into a vehicle’s engineering, but talking to Green about the design of the Bloodhound was a wholly different experience to the average automotive technical briefing.
Judging by the conversation with Green, trying to run a wheeled vehicle - powered by both a jet engine and a three-bore rocket - up to 1000mph and stopping it again requires a huge grasp of higher-level physics and maths.
Green tears into explaining the huge engineering challenges with rapid-fire reference to fundamentals you might vaguely remember from school.
Indeed, I heard him use the term ‘the area under a curve’ when taking about the calculations they needed to do when working on slowing the Bloodhound down. It’s the first reference to that concept I’ve heard since my ill-fated attempt at O-level maths in 1983.
But Green’s contribution is not just about a fundamental understanding of the physics of challenge. He’s also the best person in the world to advise on the design of the Bloodhound because of his experience with Thrust SSC.
Safety-critical areas such as the steering stability, the ability of the suspension to cope with minor dips in the desert surface (which could translate into a 30 tonne loading on the components) and how to keep the rear wheels on the ground (the rear of Thrust SSC famously lifted off), benefit massively form Green’s input.
He is, of course, the only man on earth who has experienced driving beyond the speed of sound. Perhaps his key experience in Thrust SSC was what he described as ‘hitting a wall’ as the vehicle made its 763mph maximum.
Bloodhound’s engineers named the phenomenon ‘spray friction’. As the Thrust SSC accelerated, a huge shockwave was created under the car, which ‘exploded’ the surface of the desert. The resultant plume of debris thrown up caused huge drag around the rear end of the car, preventing it from gaining more speed.
Which is why the Bloodhound is a svelte machine. With a very small footprint, out-board rear wheels and a nice upright rear end, Green should avoid sucking up the desert behind him.
And Green needs as few things to worry about as possible. He told me that once the Eurofighter’s jet engine gets him up to around 350mph, he lights up the rocket engine and should run up to 1000mph in just 20 seconds. And then, he has to slow the Bloodhound back to standstill without losing control or running out of track.
So not much pressure, then.