Bloodhound SSC

Serving RAF pilot Andy Green is again in the hot seat for a new bid to push the LSR to 1,000mph - faster than even a jet aircraft has flown at low level

Having got ourselves lost in Bristol trying to find the SS Great Britain, the Editor and I have now wandered into a small office and are surrounded by young soldiers preparing for some sort of job interview. Written on the door is ‘Bloodhound SSC Project: Reception’, but this is not quite what we expected. Anxious to not be signed up for a covert mission to Mali or somewhere equally hazardous, we swallow our pride and ask if anyone knows where we can find the Bloodhound Land Speed Record car workshop.

It turns out to be just around the corner, in a large building that previously housed part of the maritime museum. Inside there are more soldiers and, on a very substantial jig, what looks like part of a submarine. It is, we are told, the lower mid-section of the Bloodhound SSC. The car that the team hopes that next year will crack 1,000mph on a specially prepared dry lake bed ? the Hakskeen Pan in South Africa. A thousand miles an hour? Is this sensible? After all, Britain already holds the land speed record, achieved in Thrust SSC in 1997. Its driver, Andy Green, set the record at 763.035mph, breaking the ‘sound barrier’ in the process. Why does the same team, led by again Richard Noble, want to raise the bar even higher?

The answer is that the Bloodhound SSC project’s primary goal is to inspire a new generation of engineers. Youngsters growing up in the 1950s and ’60s were witness to incredible feats of British engineering: the Vulcan, Concorde and numerous fighter jets... and the sight of a Lightning standing on its tail in full reheat at the end of Farnborough’s runway must have sent dozens of youngsters scurrying back to the physics lab, eager to get into the industry that produced this amazing machine. Just as the Apollo manned space missions in the 1960s gave rise to a massive increase in students applying to study physics and engineering at US universities.

NO SECRET PLANS OR DESIGN

We are allowed to photograph everything and there are no white sheets hiding secret assemblies. Thousands of schoolchildren are following the Bloodhound project; taking part in their own projects and building their own models. They’re even able to download engineering drawings from Bloodhound and pin them up on classroom walls for inspiration. There is much to excite in this project and I defy anyone who loves engineering and technology to argue. Whatever fields excite you, there is something in Bloodhound to grab the attention.

First, we have its jet engine. Thrust 2, which in 1983 Richard Noble drove to grab the land speed record for Britain, achieved its 633mph thanks to a surplus Rolls-Royce Avon jet engine. Thrust SSC, the car Green drove in 1997, used a pair of Rolls-Royce Speys that had once lived in the tail of an F-4 Phantom, and like the Avon were rescued from the scrapheap. Bloodhound, however, is using a Eurojet EJ200 (a development of a Rolls-Royce experimental engine) supplied directly by the MoD. The engine, and the two spare units that came with it, are test units that have enough time left on them for Bloodhound’s purpose.

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Using two jet engines wasn’t going to work because the amount of drag created by the size of air intake required to feed the engines air would have dramatically limited Bloodhound’s top speed. That and the length of track that would be required to allow the gas turbines to accelerate the car to 1,000 mph. The solution chief engineer Mark Chapman and his team came up with was to use a rocket engine in parallel with the gas turbine. The EJ200 accelerates Bloodhound up to 300mph, at which point the rocket engine fires to continue accelerating the car. And here we come to the part where Goodwin wishes he’d paid a little more attention in chemistry lessons. (The head nods but the brain is furiously trying to understand the science.)

Bloodhound’s rocket motor is the work of one of my heroes: Daniel Jubb. Jubb says that “I don’t remember a time in my life when I wasn’t fascinated by rockets”. At the age of thirteen, he and his grandfather set up The Falcon Project ? a company that develops rockets. The pair used the Army’s missile test range at Otterburn in Northumberland until one of their rockets exceeded the site’s 20,000ft altitude limit. Today The Falcon Project is based in California and supplies units to the US military among others.

Jubb has designed for Bloodhound a hybrid rocket motor that uses HTP (High Test Peroxide) as an oxidiser. Up to 800mph the rocket engine will run as a single-fuel unit in which the HTP passes over a solid catalyst and decomposes into steam and oxygen, which escape out of the nozzle, producing thrust ? lots of thrust. To speed Bloodhound beyond 800mph, the hot steam and oxygen are passed over a solid fuel pack that burns and produces vapour, and with it extra thrust. The solid fuel is HTPB (hydroxyl-terminated polybutadine), which is a type of rubber similar to that used in aircraft tyres. Jubb has added various other elements to the fuel to speed up the burn rate. At full power, operating both as a liquid and solid fuel rocket, Jubb’s fantastic firework produces 27,000lb of thrust; 7,000lb more than the jet engine.

The rocket is as thirsty as it is powerful. During the run it will swallow one tonne of hydrogen peroxide. And now we come to one of Bloodhound’s systems that is closer to my patch and easier for me to understand. Delivering just under one tonne of liquid in twenty seconds requires quite some fuel pump. The team looked at using various systems to pump the fuel but settled on a conventional internal combustion engine, albeit one from the world of Formula One. The engine is a Cosworth V8 that produces around 750hp at 18,000rpm. It drives a centrifugal pump that ironically first saw service on a 1960s Blue Steel missile. This unit is designed to run at 11,000rpm, so there’s a reduction gearbox sandwiched between the engine and pump.

FASCINATING MIX OF PEOPLE

There’s a fascinating mix of people working on the Bloodhound SSC project (just over thirty full-timers work at the Bristol premises), with an interesting diversity of background. Mark Elvin is a design engineer who started out at Westland as an aircraft technician apprentice, moved up to the drawing office and in 1999 left to join the Williams Formula One team. After a stint working on railway engineering he felt the need for ‘an exciting working environment’ and joined Bloodhound. Over a coffee Elvin talks me through the Bloodhound’s chassis.

Like the powertrain it’s an interesting mix of different technologies. Starting at the front of the car we have the nose, cockpit and the EJ200’s air intake ? a masterwork in aerodynamics and fluid flow science from Ron Ayres, chief aerodynamicist on Thrust SSC and probably the most knowledgeable person on the planet when it comes to building the fastest landcraft in the world. Made from carbon fibre, this section is moulded in a single piece. The team has in the workshop for trial fitting a dummy glass fibre version of the part called a ‘flash’: the proper carbon fibre piece is currently in the autoclave. Like most of the Bloodhound’s components, the composite section is being made by an outsider supplier, one of hundreds that are providing services either at cost or less.

The lower section of the chassis, which you can see mounted upside down on its jig, is formed from sheet steel wrapped around aluminium bulkheads machined from billets and strengthened by steel sills. Steel sheet rather than aluminium is used because a soft alloy would not be able to withstand the battering received as it passed over the desert floor at 1,000mph.

In the sheet steel floor are cut access holes reinforced with machined aluminium surrounds. The largest is the access panel through which the Cosworth engine is fitted. If anything should go wrong with the motor it can easily be removed and swapped for a spare; although that’s unlikely for an engine that will be operating for the equivalent of a warm-up lap at a grand prix. The rocket engine itself is mounted in a tube at the rear of the chassis. At the end of each run ? for the record to count Bloodhound has to make a run through a measured mile (the track itself is twelve miles long) and then return in the opposite direction within sixty minutes ? the rocket engine will be removed and replaced with a fresh engine complete with its solid fuel ‘grain’. The initial design had the rocket engine sitting piggy back on top of the jet engine but during computer simulation the team discovered that the nose was trying to bury itself in the ground. This could have been fixed by using adjustable winglets to the side of the nose but the risk of an actuator failing or a computer malfunction ruled it out as too dangerous. Instead, the EJ200 is placed on top of the rocket. There’s little penalty as far as centre of gravity goes as the rocket engine sits low in the chassis and is easier to package than a gas turbine.

The jet engine itself is mounted in a superstructure that’s much more aerospace than motorsport. There’s a conventional skin, bulkheads and stringers. Likewise the tail, according to Elvin, is very similar in design to that used on a Hawk trainer. Tried and trusted technologies there. Very different to our next subject; wheels.

MADE FROM A NEW AIRCRAFT ALLOY

Wheels have been an issue for land speed record cars since the sport was invented. Like Thrust 2 and Thrust SSC Bloodhound is using aluminium wheels with a v-shaped rim that cuts almost like a boat’s hull into the lake bed’s surface. The tricky bit is that at 1,000mph they will be turning at 10,200rpm and at this speed there will be a force of 50,000G at the rim. The wheels are made from a new type of aircraft alloy that’s stamped by a 30,000 tonne forging press from a billet into a disc. The forgings are produced by German company Otto Fuchs (who made Porsche’s famous wheels) and then finished by Castle Engineering in Glasgow.

One of the most complicated parts of the project has been designing and incorporating the various systems. Some things are not as simple as they might seem. The EJ200 jet engine, for example, has a very advanced control system that in fact throws up a few issues. One is that the engine’s ECU knows when the Eurofighter’s undercarriage is down and not being able to detect an undercarriage at all, let alone one that is up or down, upsets it considerably. To get around the problem the team have had to write special software to reassure the engine that all is well. There was a concern that the Bloodhound’s three-G deceleration might strain turbine blades that on the Typhoon only experience high forward acceleration forces. No, said Rolls-Royce; it will be fine. The braking system itself is a three-part system. Below 200mph steel brake discs slow the vehicle (carbon fibre discs are no good as they shatter at high rpm). High speed braking is done by airbrakes backed up by two independent parachute systems.

Now, back to the army. In one corner of the workshop can be heard the fizzing noise of a TiG welder. It’s being operated by Lance Corporal Graham Sargeant, REME, one of a group of army engineers on secondment to the project. It’s a fantastic cross-pollination of experience. For Sargeant it’s an insight in to a world quite different to the one he’s used to. “I’ve been hugely impressed by the amazing standard of hand skills of the guys working on the project.” The Bloodhound regulars must in turn be very impressed by the maturity and skill of this youngster who has been in the unusual position of going into a combat zone with a rifle in one hand and a spanner in the other. That’s one of the army’s motives for placing personnel in the Bloodhound project: it hopes that youngsters will realise that army engineers and technicians do rather more than change lorry wheels in the desert.

Later this year the team will prepare to run Bloodhound on an as yet unnamed airfield runway in the UK. The aim, running on new old stock English Electric Lightning tyres, is to get the vehicle up to around 250mph to test systems and controls. All being well they will then ship out to Africa in 2014 to try to push the land speed record to a new extreme. There are rival teams working in America and Australia. But, in truth, nobody can match the experience and knowledge of our British team. I was one of those who doubted that breaking the sound barrier was possible. I wouldn’t want to risk wagering a packet of crisps against them succeeding in this latest challenge. And neither, I suspect, would the thousands of schoolchildren who are both following and involved in the project.