vol 8, issue 10

UK companies contibuting to the 1,000mph car

14 October 2013
By Sean Davies
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Bloodhound record breaking car graphic

British engineering features highly under the skin of the 1,000mph car

Bloodhound diffuser floor

The interior components are painstakingly machined from aerospace-grade aluminium

Bloodhound steering wheel exploded view

The steering wheel was initially designed in clay to achieve a perfect fingerprint fit for Green

Bloodhound SSC carbon fibre monocoque

The carbon fibre monocoque provides a strong core for the car, weighing six tonnes dry (seven-and-a-half fuelled)

Bloodhound SSC Rolls Royce engine

Three engines power the Bloodhound, featuring single crystal blades and wide-chord aerofoils

When Andy Green attempts to break the land speed record in South Africa in 2015 his Bloodhound car will be showcasing an array of UK engineering excellence under its skin.

It was just over 15 years ago that Andy Green powered Thrust SSC to a shade over 763mph on Nevada’s Black Rock Desert to improve on his own land speed record. But when Green sets foot on South Africa’s Hakskeen Pan in 2015, breaking that record will not be enough. The plan is to shatter the record and top the 1,000mph mark with his Bloodhound jet/rocket hybrid. In early summer of 2015 the car will take to the runways of the UK’s Newquay airport before being flown directly to South Africa to start carrying out high-speed testing. That year the team will limit itself to breaking the land speed record before analysing the data and returning the following year with a fully hybrid rocket car to reach 1,000mph.

“The whole thing about this is the challenge,” Mark Chapman, chief engineer on the Bloodhound Project says. “If you wanted to just break the record, to get an 800mph car, then you could take ThrustSSC out of Coventry Museum, pimp it a bit and you could probably get that car to 800mph.

“There is such a leap to go from 760mph to 1,000mph, it is completely unknown. That is the whole ethos of this project as we are an educational project. It had to be genuinely difficult and challenging and this is why we are doing it.”

Rules of the game

Formula One has a rules and regulations book the size of a telephone directory, but the land speed record rules are four lines on a single sheet of A4. The car has to be driven; it has to be in full control of the driver; you have to do the run in two directions for a measured mile within an hour; and you have to leave wheel tracks.

For Thrust SSC assessors had to walk along the measured mile to check that there were indentations and that it had in fact stayed on the ground the whole way through. “For the speed we will be doing that is almost irrelevant as - although we will definitely stay on the ground - we will also achieve the air speed record as well in that we will go faster than any aircraft has at that altitude. Even if you had a jet fighter, there isn’t a jet fighter that has gone that quickly at that altitude before. We will travel about 25 per cent faster than the aircraft that we get the jet engines from, the Eurofighter Typhoon.”

It is almost six years since Chapman joined the Bloodhound project and in that time he has guided the project from a blank sheet of paper to the stunning car that is taking shape at the team’s headquarters.

That design has always been a moveable feast, evolving as expertise from suppliers is incorporated into the master plan.

The original plan was for a pure rocket car before it developed into a jet and rocket hybrid, but with a completely different configuration to what we see now. It had a split intake and was much longer, coming in at around 20m in length. The front wheels were tandem, one in front of the other, in an attempt to try and keep it as narrow as possible. “Myself and Brian Coombs, the lead mechanical design engineer, started on the same day,” Chapman says. “We spent the first couple of months trying to work with something that was better packaged as the original car was so big.”

The jet engine was always planned to be the Rolls-Royce EJ200, although initially they were not sure how to get hold of one. The original car had an MCT V12 normally aspirated engine, but as time went on that changed to a Cosworth F1 powerplant.

One of Chapman’s first tasks was to convert all the early work into CAD models to allow different configurations to be assessed as well as for stress and aerodynamic analysis to be carried out. The CAD work was undertaken on Siemens NX PLM software along with other packages for stress such as Altair HyperWorks.

“We carried out a quick six-week trade study between a whole range of different options,” Chapman adds. “Some were open-wheelers, some were with Andy Green in a very low-seated positions, others with him in a very upright position and some even had him in front of the front wheels.

Aircraft, racing car and spaceship

“It was almost starting with a clean sheet of paper then configuring the packaging adding Andy Green, two engines and the car engine into the space and seeing what kind of shapes we could come up with. Then we would do a sort of matrix on these concepts for stability for drag and different variables that we had to consider before coming up with a winner.

“Within eight weeks we had a car, which, if you squinted, looks much like the car we have now. The main difference is that after about a year we decided to swap the jet and the rocket. This solved dynamic stability issues; when the rocket was fired it would have buried the nose in the ground. Swapping the two engines around worked better because both those thrust lines straddle the centre of gravity and it made the car a lot more stable during the transition between pure jet and then combined jet and rocket at the same time.”

Free from the constraints of the traditional automotive platform or tooling restrictions, the team had only to worry about adhering to the most aerodynamically efficient form manageable. “It was all about juggling it, but function drove it,” Chapman says. “There were some early studies with chief aerodynamicist Ron Ayers where we were going back to 1950s and 1960s aircraft design where they were doing very low-drag transonic designs. Some of the car design has been driven by the research done at that time on what we call ‘anti-drag’ bodies.”

Unique, challenging, unconventional. The project has been labelled with these and many other metaphors, but it certainly requires a different way of thinking. The engineering team needs the ability to solve complex engineering problems, often without the safety net of industry practices. “This project is part racing car, part aircraft and part spaceship,” Chapman adds. “We have got a very wide range of people and with the skill set we need for this project people have dabbled in lots of different of things. We have guys who are ex-Williams F1, guys who are ex-rail systems, and it is much more about the engineering skill and gut feel of the people we work with.

“This project is simply so different that we need people who, either through breadth of experience or having worked on more unusual projects, have had those blinkers removed and are really prepared to think about unusual challenges.

“We have had some challenges on this project where it has been really hard to come up with any answer; we couldn’t see a resolution. We had to go back and look over the questions we were asking and then change those questions into something that we could answer and accepting compromise on certain parts of the vehicle.”

The team relies heavily on the expertise of suppliers - more aptly described as partners. For the companies involved in the project it is not about financial gain; the vast majority work free of charge or at a substantially reduced rate. For them it is about showcasing their talents outside the restrictive world of top-level motorsport, aerospace and defence where their achievements are hidden by non-disclosure agreements.

Challenges of speed

“We will shortcut a lot of what most companies will do. We have come up with the design, handed it to the manufacturer for design review and we try to get that process working an awful lot earlier to use their expertise and industry knowledge to influence how we design things.

“[Given that] we are not fixed to exactly what we have to do, if someone comes to us with an idea on how to change something we can adapt. We are constantly updating and releasing new designs and there is an opportunity for them to have their input.”

Unlike a Formula One team, which can take its car on the track and test endless parts at full speed, running on this project will be strictly limited. In fact the car will only ever go 1,000mph twice - maybe three times - in its whole life. “We will need to rely on a lot of computational methods. We have actually just completed, at AMRC, some testing for the pull rods where we tested them for fatigue and strain.

“But we can’t try out a 1,000mph run before we actually put Andy in the car so the whole run profile is built up of gradually increasing the speed, but then also using the data, as we get it off the car, to correlate our computational models.

“Every time we go a bit quicker we will then check the data off the car with what the computer predicts we should see, and provided they stay correlated we will keep increasing the speed. If they start to diverge we would then look at why this was happening, and then make the model better to reflect the reality of what we actually see and then use that as a way to predict what we expect to see moving forward again.

“The continuous process as we approach 1,000mph is to make sure that our computational model matches what we see in reality. It is very much that we will learn all this information to improve all the modelling and go forward with those.”

If they succeed in topping the 1,000mph mark it could signal the end of further record attempts as Chapman explains. “There is a limit. There are factors, like wheels, where there may be a point that you simply cannot make a wheel that will withstand the forces.

“However, the biggest problem is actually slowing the car down and finding a length of desert to allow the car to run on. It is relatively easy to accelerate quickly, but to slow the down is bigger challenge than getting it up to speed. You can’t use wheel brakes, you have to use air brakes and parachutes, and there is a limit to how much of a car you can open out into the wind and just relying on aerodynamics to slow you down.” 

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Bloodhound Hybrid

1 Body parts are machined from high-grade aluminium and include complex forms such as machined latticework and aerodynamic sculpting.

2 The biomimetic, 3D-printed steering wheel includes haptics and a fingerprint fit for its driver.

3 Wheels will be the only point of contact between the car and the desert and are made from pure aluminium to withstand the heat.

4 The complex wiring loom will interface several hundred sensors from all over the car.

5 Bloodhound requires three engines to propel it, meaning lower fuel consumption was an important factor during design.

6 Achieving an aerodynamic, light and strong body for the vehicle took 1,000 hours, using seven layers of carbon fibre.

Bloodhound Partners, part 1

Six of the UK's top engineering companies are playing an integral part in engineering Andy Green's 1,000mph land-speed dream.

High-value machining: Nuclear AMRC

For the intricate task of machining body parts out of solid blocks of aerospace-grade aluminium the Bloodhound team turned to Nuclear AMRC at Sheffield University, formed as part of the government's Low-Carbon Industrial Strategy.

Seven parts are being produced on the giant machining centres at Sheffield. The main component is the rear sub-frame. This is the assembly that holds the car's rocket engine and provides stability. These are large parts that will be holding some 120,000N of thrust. One such part is the diffuser floor. This features a complex pattern of latticed pockets on the top side, with an aerodynamically sculpted reverse. It will sit beneath Bloodhound's hybrid rocket engine, and provide the downward force to keep the car on the ground as it reaches 1,000mph.

Four parts are being produced on the HEC1600 horizontal machining centre, with the remaining three parts made on the Hermle C60 U MT five-axis machining centre.

It took almost 200 hours of machining on the Hermle to produce the finished diffuser floor. The 55kg diffuser floor contains just one-ninth of the metal in the original 480kg aluminium billet provided by Alcoa.

"The biggest challenges were the deep pockets, which are up to 155mm deep," says Mathew Challinor, NC programmer at the Nuclear AMRC. "This is very challenging for tooling, as you need a tool that has a length of 15 times its diameter. Fixturing was also a challenge, as we had to avoid vibrations in such a slender aero-like structure, while making sure the part was held securely.

"The learning curve for a machine with the capabilities of the Hermle is very steep, but the Bloodhound project has allowed us to make rapid progress. We have been able to really push our roughing cycles to reduce our times and also test the rigidity of the machine. With the complexity of some of the Bloodhound parts, the finishing operations will really show the Hermle's full simultaneous five-axis potential."

The Hermle's on-machine probe has also been a great asset, Challinor notes. "That's allowed us to perform on-machine verification on critical features, and to check they conform to drawing before the parts leave the machine," he says. "The data we're collecting will be used to benefit future projects."

Steering a passion: Cambridge Design Partnership

Design consultancy Cambridge Design Partnership is finalising the design of the steering wheel for manufacture. The initial steering-wheel design was created by the Bloodhound team using a number of novel design techniques including bio-mimicry and crowd-sourcing, with early concepts being developed in clay from driver Andy Green's hand imprints in the triple-layer fire-proof gloves he will wear.

These initial concepts were optimised for driver ergonomics and reaction time, whilst creating a design ready for manufacture. A whole range of considerations have been included, from the shape of the handgrips to the haptics and location of the buttons and switches which operate the jet and rocket engines as well as parachutes and communications systems.

The steering wheel is manufactured using the latest titanium 3D printing technology which facilitates complex geometry and a high strength to weight ratio, offering great freedom in both form and ergonomics.

Bloodhound Partners, part 2

Keep on running: Castle Precision Engineering

One of the greatest engineering challenges that the Bloodhound team faced was designing and manufacturing wheels that can survive the forces at 1,000mph. The wheels will be the only point of contact between the 135,000hp jet and rocket powered car and the South African desert.

The 90kg, 900mm diameter solid aluminium wheels will spin up to 177 times per second at top speed, withstanding a load of 50,000 radial G at the rim while, as the 7.5 tonne jet and rocket powered car blasts across its South African desert racetrack in 2013 and 2014.

They are the product of a three-year study by Bloodhound engineers and renowned aerospace company Lockheed Martin UK. The challenges the team had to overcome included creating a design that would not fly apart when turning 10,200 times per minute, and which could be manufactured to incredibly tight tolerances with zero distortion.

"Our background and experience of manufacturing critical aero engine components means we have the investment, skills and the expertise to deliver on the highly critical nature of these wheels," Marcus Tiefenbrun, managing director of Castle Precision Engineering, says. "Our involvement on the project forms an integral part of our own drive to encourage and attract the next generation of talented young people into engineering. This is vital to the rebalancing of the economy and UK industry that is based on innovation and high-value manufacturing."

Looming challenge: DC Electrics

DC Electronics' involvement with the Bloodhound project is to provide the wiring harnesses for both the land-speed record challenger and the associated support vehicles. They are also supplying its electric power steering motor and control ECU for the Bloodhound.

"To date we have supplied the power and data harnesses for the lower chassis assembly," David Cunliffe, director of DC Electric, says. "Most of the data systems are Ethernet and the main challenge here was to find a suitable cable that could withstand the production procedure as these cables were installed prior to the final skin being applied and the whole lower chassis then being placed in an oven to be cured.

"Many hours of cooking test pieces were carried out until a suitable cable was selected. All wiring harnesses have been colour coded so that systems can be very quickly identified when the vehicle is out in the field should the need for maintenance or rectification be required."

The power-steering system comprises a moto/gearbox, control ECU and a dual channel strain gauge and amplifier that is fitted to the steering column. Dual-channel sensors are used for built-in redundancy. The turning force applied at the steering column is measured and fed into the control ECU, this in turn powers the motor/gearbox that is mounted inline between the steering column and steering rack to rotate in the required direction and speed.

"The most complex part of the project is still to be undertaken, which will be interfacing the several hundred sensors located across the vehicle with all of the control computers," Cunliffe adds. "From our side no specific new technology has been designed for our part of the project (including the steering system which we use on Le Mans race cars)."

Bloodhound Partners, part 3

Jet power: Rolls-Royce

Three engines power the Bloodhound – a Falcon hybrid rocket engine, a Cosworth CA2010 F1 engine, and a Eurojet EJ200, a highly sophisticated military turbofan normally found in the engine bay of a Eurofighter Typhoon.

The EJ200 is a twin-shaft reheated turbofan, with three low-pressure and five high-pressure compressor stages, powered by two single-stage turbines. The combustor is annular with airspray injectors. The engine reheat system features a three-stage manifold system and a convergent/divergent nozzle. Engine control is by an integrated Full Authority Digital Engine Control (FADEC) system.

The technology of the EJ200 engine makes it smaller and simpler in layout than current powerplants of a similar thrust class while giving it lower fuel consumption and an unprecedented power-to-weight ratio.

Among the most advanced features of the EJ200 are a fan design that gives high stability without IGVs, the application of blisks, wide-chord aerofoils, single crystal blades, an airspray combustion system, and an integral FADEC providing low pilot workload.

Perfect body: URT

URT has now completed construction of the car's carbon-fibre monocoque. This is where Andy Green will sit when he aims to become the first person to drive at more than 1,000mph.

URT spent more than 1,000 hours producing this major chassis section, with the help of equipment previously used in building the pods for the British Army's Foxhound light-protected patrol vehicle. Stretching from the tip of the nose to the air intake, the monocoque houses the cockpit and controls and has to carry a rocket oxidiser tank containing 1,000kg of hydrogen peroxide, the front suspension and steering sub-assembly, and the jet engine intake.

The monocoque is about 20mm thick, with a seven-layer carbon outer skin,'foam core and five-layer carbon inner skin. Lightweight but ultra-strong, this will provide the strength in the centre of a car weighing 6,000kg dry, 7,500kg with fuel.

It will experience aerodynamic loads of up to 12,000kg per square metre and have to withstand acceleration and deceleration loads of up to 3G – equivalent to the forces generated by going from 0-60mph, or 60-0mph, in just one second.

"When I'm sitting in the cockpit of the Bloodhound SSC, I'll know that it has been built by the best in the world," Andy Green says. "These guys work with Formula One teams on a daily basis and the Bloodhound SSC's monocoque has been manufactured using the same equipment that was used on the Foxhound military vehicle – that's incredibly reassuring."

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