LSR: Bloodhound SSC Technical Galleries

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    LSR: Bloodhound SSC Technical Galleries

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    Craig Scarborough posted in
    Everything Technical

    As the Bloodhound project has progressed, last October the Land Speed Record (LSR) car reached a milestone, as it made it first Jet powered runs on a runway in Newquay, England. This project has evolved from the same team that broke the sound barrier in Thrust2 and are now aiming for another record at 1000mph.

    To achieve this, the vehicle is very different from Richard Nobles previous projects, by having both jet and rocket power to propel Pilot Andy Green to this incredible speed. This is very much a ‘car’, there’s four wheels, a cockpit, chassis and suspension, but any similarity soon becomes blurred as the vehicle’s design is part racecar and part jet fighter. Behind the long nose, starts a carbon monocoque, visually similar to an oversize F1 car, then behind this starts an aircraft-like structure of aluminum bulkheads and rivetted skins.

    Inside this rear structure sits three power units, the aforementioned Jet, three rockets and additionally a powerful motor to drive the pump to feed oxidiser into the rockets. Any project of this scale and complexity changes over time, so while the Jet has always the Rolls Royce EJ200 from the European Typhoon jet fighter, but the Rocket spec has changed from a single to a triple set up. Then the pump motor has been re-specified three times, from a Race engine, to a Cosworth F1 engine, then a supercharged Jaguar road car engine and now the plan is to use an electric motor powered by batteries in the nose cone.

    Again the “is it a car, is it a plane?” analogy is applied to other aspects of the car, there is pull rod suspension akin to that raced in F1. Then, there’s supersonic aerodynamics that could be applied to a plane, but of course Bloodhound runs at a few millimeters above ground level, no plane does that! To keep the vehicle stable at speed is an active system, but one affecting the aero surfaces, rather than the suspension, as on a racecar.

    I’ve been lucky to follow the project for several years, so to mark the first runs, I’ve compiled a series of galleries to show the car in its current state of build in Newquay this year and the construction stages back at the Bristol headquarters over the past few years.

    Monocoque

    Quite possibly the largest carbon monocoque produced for a car, the Bloodhound tub is certainly larger than a F1, LMP1 or Supercar. Only when Andy Green is sat in the drivers seat, do you realise the scale of this part! Forming the front section of the car’s structure, the tub houses the cockpit, front suspension and forms the jet-pipe inlet above the cockpit. The tanks flanking the cockpit sides hold cooling water, for the Combustion engine that was planned to drive the rocket fuel pumps.

    Rear Structure

    Behind the carbon tub, the car is formed with an aircraft-like construction. Huge machined aluminium bulkheads span the body, which are then tied together with titanium skins and stringers. Riveting the skin to the structure has been an enormous task, each hole needing to be drilled, countersunk, be-burred and temporarily held with ‘cleco’ fasteners before final riveting. IT was formed in upper and lower halves, before the two were assembled together.

    Suspension

    The car has double wishbone pull-rod suspension on all four corners, while recognisable as typical racecar setup, but due the weight and speed of the car, the components are oversized for strength. At the front the suspension assembly mounts to an aluminium structure boded to the carbon tub. This part being the ‘goats head’ due its resemblance in shape.

    Outboard there are aluminium uprights, these also form part of the AP-Racing brake caliper, which for the airport runs used carbon discs. The wheels were forged specially for Bloodhound by Lockheed in the USA, rubber tyred wheels were used for the airport runway tests, but will be replaced with solid aluminium wheels for the runs in the desert. Their ‘tread’ profile forms a slight “V” in the centre, at speed the wheel will ride up through the sand, so that just the tip of the wheel profile runs through the sand.

    Cockpit

    Formed into the carbon tub, the cockpit is another part-car and part-jet fighter feature. Sat in a Racecar style carbon seat (No ejector seat!) in his Alpinestars race suit boots and Arai helmet, Green’s head is rested between typical racecar style foam padding within thin carbon skins. The view out of the closed cockpit is formed from a forward screen built into the tub, then the removable cockpit hatch cover has small viewing ports built into its sides. The controls are largely Aircraft style with the yoke handlebar control, made by 3D printing in titanium. While the foot pedal controls the jet, the rocket firing is achieved with a trigger on the steering yoke. The slide controls to the side of the seat are for the parachutes and there’s a foot pedal for the brakes. With three LCD screens and a host of control buttons, there’s still space for a paper check list, notebook and ballpoint pen! While as time-is-of-the essence and timing critical to make the two measured passes across the FIA timing equipment, Rolex supply the cockpit clock and team’s watches

    Rolls Royce Jet

    Mounted to the aluminium bulkheads high up in the rear structure and fed by the inlet over the cockpit. The Rolls Royce EJ200 jet engine with afterburner will quickly push the car to over 200mph, in the Newquay tests, this speed was reach with just over two seconds of thrust. According to Green that’s 9 tonnes of thrust! The jet will continue to run throughout the run to the top speed.

    Multipack Rocket

    Not mounted for the runway test are the rockets, there will be three rockets fitted inside the lower section of the rear structure. These Nammo rockets are designed to lift European satellites into space. They will fire to accelerate the car from about 400mph providing some 12 tonnes of thrust, at this point the car will accelerate at 2g, gaining 40mph per second! Being hybrid rockets, they use both a solid fuel and an oxidiser, these being synthetic rubber and Hydrogen Peroxide (HTP). The rubber sits within the rocket body and the liquid HTP is pumped through into the rocket. At 200mph Green will prime the rocket with the left hand trigger on the steering yoke, the electric motor pumping the oxidiser to heat up the unit up to 600c, then with the right trigger he will fire the rockets to full thrust.

    HTP Pump

    It’s odd with so much incredible technology in the Bloodhound car, that a key talking point is the fuel pump. But at 1000mph this is no simple pump! To feed the Hydrogen Peroxide (HTP) fast enough into the three rocket motors needs some seriously throughflow, so the pump has had several specification of motor, each able to drive the pump at 40l per second. The spec signed off and built for the runway tests, even though it wasn’t required, was for a Jaguar Supercharged V6 engine. Hence the car had a large space inside the front of the rear structure for the motor, plus fuel tank, airbox inlets and cooling tanks. The cooling tank flank the cockpit, these would have held cold water to feed through the engine, as it wasn’t aerodynamically practical to feed a water radiator. The shaft-driven huge pump will now have an electric motor, with batteries positioned in the nose, which will aid weight distribution.

    Feeding the pump that feeds the rocket motors, is a huge tank to hold enough HTP to last the entire run. Made in stainless steel and with a 1000l capacity, the HTP tanks sits in the back of the monocoque.

    Aerodynamics

    As the target 1000mph top speed is well over the sound barrier at sea level, the aerodynamics have to cope with subsonic, transonic and supersonic air speeds. The team have already exceeded the sound barrier, so there is already experience within the team of these particular issues. Again, the team turned to aerodynamicist Ron Ayres, with a CV that includes the Victor “V” bomber and various British defence missile programmes.

    Critical in allowing the car to break through the sound barrier is the nose controlling the shockwave around the car as the car reaches speed where the air is incompressible. Thus, the car sports a long pointed nose, further issues then arise, if the shockwave passes under the car the forces rip up the desert surface, as evident on the Thrust SSC runs. With Bloodhound the shockwave is better managed, the air under the car is near ambient pressure, keeping the sand pristine below as it passes over. Over the nose, the jet engine needs to breathe subsonic air, so the shape of the upper front bodywork surfaces slow the air down to 550mph.

    Managing the cars load at the wheels, keeping it neither pressed into the desert surface nor becoming airborne, the rear tail plane (missing from the Newquay test) will be actively controlled to manage wheel load at around 1.5 tonnes. Then there’s a tall fixed tail fin to maintain yaw stability.

    Slowing the car from 1000mph, initially the cars inherent drag will slow the car at 3g. 1000mph down to 940mph will take about a second, down to 880mph will take bit over a second. At 800mph the air brakes come into play, they also provide around 3G deceleration. High speed parachutes can be deployed from around 650mph, these each give a sudden 1.5g deceleration. Finally, at around 200mph the wheel brakes will halt the car to a standstill in about a mile.

    Newquay Runs

    The Newquay week saw the engine fire in the chassis for the first time, the car being tethered to prevent it running away. Then the first dynamic runs, with the only the jet powering the car. The runs on the Friday, where attended by a huge diverse crowd and the media. The car towed the taxi way before Green and the engineers completed a thorough system check around the car. Then the external generator powered the jet engine’s starters, the EJ200 quietly firing and spooling up to idle. Then Green taxied around the runway before turning with a surprising tight turning circle to the start of the, now closed, runway.

    Barely pausing from the taxi, he opened the throttle and afterburner for two seconds and the car shot down the runway, reaching in excess of 200mph. Green completed two such runs before parking the car to cool down before the media again descended around the car for more interviews.

    The half-finished look of the car can be explained by the runway-specific rubber tyres being too large for the final bodywork to fit over.

    Video clips

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    0:09

    High speed run

    Play video
    0:33

    Taxi run

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    Comments (2)
    • Pretty sure the wheels were not actually forged in the USA. And Thrust2 did not break the sound barrier.

      1 month ago
    • Great write up Craig. Top Work!

      1 month ago
      1 Bump
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