The news that Geely has become Bloodhound’s main sponsor has reignited interest in the supersonic project’s 1,000mph record attempt.
The backing means that Richard Noble, Andy Green and the rest of the Bloodhound team now once again look set to hold the world’s attention at Hakskeen Pan in South Africa with a daring and accomplished feat of British ingenuity.
Geely is the largest privately-owned automotive company in China. It owns Volvo Group and also makes London black taxis. The company is providing enough money to clear Bloodhound’s debts and pay for its ongoing costs.
Bloodhound’s first 800mph record attempt will take place during October next year. A second run to take the car to 1,000mph is planned to take place during 2018.
Bloodhound’s project director Richard Noble says: “People now understand that Bloodhound is going to happen. Geely brings financial resources to bear, will share the technology and enable us take Bloodhound’s message to a much larger global audience.”
Tests with the rocket engine and mono propellant are planned for next June, followed by a low-speed run in Newquay, Cornwall during the summer. For the 1,000mph run in 2018, the single rocket fuelled by mono propellant has to be replaced with a cluster of three hybrid-fuel rockets so that the Bloodhound car can reach the higher speed.
Next October’s record attempt will take place 20 years to the month after Bloodhound’s predecessor, Thrust SSC, set the existing land speed record of 763.035mph. That 1997 achievement is the longest-standing record in the history of land speed records.
The team’s focus is naturally on whether the Bloodhound car will reach the required speeds, and there is an inordinate amount of impressive engineering going on to support the effort to reach this target. There are lots of examples of the depth of UK engineering expertise and capability within the sub-component parts of the Bloodhound car.
The manufacture and assembly of the car requires a level of precision that is normally only reserved for jet fighters. The company that is supplying the measurement equipment to Bloodhound also works with BAE Systems to make the Eurofighter Typhoon fighter aircraft.
Accurate assembly
Bloodhound’s engineers and technicians are using the latest 3D laser-scanning and measurement equipment to verify that components, sub-assemblies and body parts are manufactured to the correct size, and also to ensure that everything is assembled to within an accuracy of the width of a human hair, 0.05mm.
Jon Kimber, product line specialist at Hexagon Manufacturing Intelligence, says: “This level of accuracy is essential to reaching 1,000mph and coping with the speeds, aerodynamic forces and loads. The technology simply wasn’t available with the Thrust cars.
“The real key is to have that high level of accuracy and precision alignment all over the car, for all the individual parts. We even measured Andy Green to produce the seat. Without this precision, the car couldn’t run.”
The fin is the hardest working that has ever been built on any vehicle, adds Kimber. If it is just 1mm out when it is fitted onto the body of the vehicle it could create massive turning moments that could be disastrous for the record attempt.
Hexagon has supplied a Leica laser tracker for measuring Bloodhound. The system uses a combination of a tripod-mounted camera, lasers, reflector targets and handheld devices to obtain highly precise measurement data using horizontal and vertical angles and distances.
All of the car’s parts are measured, point by point, to build up a 3D point cloud, which can then be verified against the 3D CAD designs using software.
The same system will be used when the car is reassembled after being transported, first for the trial runs and then for the final run in South Africa. Embedded targets on the car and a 20-point auto-measure software routine will ensure that parts are reassembled precisely relative to each other.
“It’s not the only check, but you want as many checks as possible when running a 1,000mph car,” says Kimber.
Benefits of Bloodhound
Hexagon’s involvement in the project underpins the entire enterprise, from the initial production of the car to the final run. As well as having the satisfaction of being involved in such an inspiring project, Kimber says the company has received lots of tangible benefits from its participation.
“We do a lot of commercially sensitive work, and it’s great to be able to use open and free intellectual property to help promote the company’s capabilities,” he says. “It’s also opened doors and reinforced our existing relationships.”
Just as important as the car’s assembly is the slowing down after the run, not least to the driver Andy Green, who says, “getting to 1,000mph is optional, slowing down afterwards is compulsory!”
The brakes have three main systems: air brakes, parachutes and wheel brakes.
Detailed design and engineering experience has paid dividends with the parachute system. Marlow Ropes of East Sussex, which has been operating since 1807, is supplying the ropes that will connect the parachute to the car. This seemingly simple job presents a difficult challenge.
Paul Dyer, technical manager at Marlow Ropes, says: “The job of the rope isn’t just slowing the car down. It also needs to mitigate the impact of the deceleration from the parachute. When the parachute explodes out of the can at 800mph it picks up kinetic energy before it deploys. It’s that energy that has to be dissipated.
"We are designing around a 130kN, 13-tonne shock load and a steady-state deceleration of around 90kN, 9 tonnes of force."
Each of the ropes will be 10m long, 3.2cm in diameter and weigh 15kg. They will be made of nylon, which Dyer says still represents the “state-of-the-art” for energy dissipation. But the ropes will also feature a length of fabric called Technora, a Kevlar-like material. This piece of fabric will be put in at the end of the ropes near the attachment points of the car.
Weak link
The section of Technora is a redundant safety measure. If the parachute deploys above the speed of 800mph, the shock load would be more than the attachment point could take. The weak link of fabric will tear, ensuring the entire back section of the car isn’t torn away by the force of the parachute deploying. Technora is being used because of its resistance to heat – the attachment points are mounted near the rear of Bloodhound’s rocket engine, where the temperature could reach 6,000°C.
Dyer expects the specification of the rope to change after the test runs: “There are some considerable unknowns around when the parachute deploys. When the runs happen the system will be tweaked and the size may be lowered,” he says.
Just as vital as braking is supplying the fuel to the engines. The fuel system has a main jet tank and two auxiliary tanks. There is also a very small petrol tank to power the auxiliary power unit for the peroxide pump.
The fuel tanks are being supplied by Advanced Fuel Systems, which provides similar tanks to motorsport, including Formula One. The main fuel tank for Bloodhound is not a metal box, but a “bag” manufactured from a strong, flexible composite of nylon and polyurethane. The bag can deform if an accident occurs to allow the fuel to be moved away from the trouble spot but remain contained.
The outer structure is made of the composite, and is manufactured by using a method similar to a wet lay-up process, allowing the company to form it to a more tailored shape and get a more optimal fit. Bloodhound’s acceleration will create 2.5G, pushing all the fuel to the back of the tank. As with the ropes, the most challenging aspect is what happens when the car starts decelerating.
Jonathan Tubb, managing director of Advanced Fuel Systems, says: “At the end of the measured mile, during the deceleration process, the jet engine still needs to be running because it’s consuming a huge amount of air at the front of the car. If it wasn’t running, the air would be stalling against the compressor, spilling out of the front of the intake. The car would become unstable.”
Managing fuel movement
Inside the tank the 3G created by the deceleration will affect the position of the fuel, effectively tilting it upwards 72°. To ensure that the fuel is at a point in the tank where it can be used, engineers have devised a series of internal louvres, which hold the fuel in place.
“It’s quite complex,” says Tubb. “The fuel moves backwards under gravity because of acceleration. As that becomes deceleration the gravity acting on the louvre closes the slats, pushing the remaining small amount of fuel forward that is trapped.
“We start with 550 litres of fuel. About the time the car’s decelerating there might only be 60 litres left, but it’s vital that it can be picked up. With our pump system it can be.”
Engineers have used a combination of simulation, computational fluid dynamics and practical tests to develop the tank. Most of it has now been built and the engineers are looking at the leakage in the louvres and ways to optimally fill the tank.
Advanced Fuel Systems also supplied the fuel system for Thrust SSC. Tubb says: “The material density for a similar strength is less this time and the louvre system is more complex. But the packaging has also been a real challenge. Bloodhound is a huge car, so you’d think there is plenty of room, but it’s incredibly tight in there.”
Tubb agrees that there have been benefits for his company from being involved with Bloodhound. “We get brand awareness and the project has this wider appeal, which is great,” he says. “Engineers everywhere love it and want to know more about it, and we can tell everyone about our role, which for us is quite rare. It opens a lot of doors and gives us a lot of credibility.”