Bloodhound SSC Show Car unveiled in India

THE TECHNOLOGY BEHIND BLOODHOUND SSC        

According to a press release issued earlier, in June 2014 the cockpit of the vehicle was unveiled. Hand crafted by URT Group using five different types of carbon fibre weave and two different resins, the monocoque has taken more than 10,000 hours to design and manufacture. Sandwiched between the layers of carbon fibre are three different thicknesses of aluminium honeycomb core (8, 12 and 20mm), which provide additional strength. At its thickest point the monocoque comprises of 13 individual layers but is just 25mm in cross section.

The structure weighs 200kg and bolts directly to the metallic rear chassis carrying the jet, rocket and racing car engine. The carbon front section will have to endure peak aerodynamic loads of up to three tonnes per square metre at 1,000mph (1,609kph) as well the considerable forces generated by the front wheels and suspension. It will also carry ballistic armour to protect the driver should a stone be thrown up by the front wheels at very high speeds. The roof of the cockpit has been designed to create a series of shockwaves that will channel the air into the Eurojet EJ200 jet engine.  If supersonic air reaches the jet engine fan blades, the airflow will break down and the engine will ‘choke’ (known as a ‘surge’). This can generate huge changes in pressure that could damage both the jet engine and Car, hence Bloodhound SSC using shockwaves over the canopy to slow the airflow from over 1,000mph (1,609km/h) to just 600mph (643km/h) in a distance of around one metre.  Deflecting winds travelling five times faster than a hurricane will, however, cause additional noise and vibration to be transmitted into the cockpit. The cockpit is positioned in front of three incredibly loud motors: the jet, a cluster of hybrid rockets and the racing car engine that drives the rocket’s oxidiser pump. Collectively they will generate a noise level estimated at 140 decibels. Much of the noise will be directed backwards, away from the driver, and above 750mph (1,207km/h) the car will out-run its own sound waves. However, the Project’s engineers still anticipate that shockwave and jet intake noise levels may produce over 120 decibels inside the cockpit. Andy will wear an in-ear communications system specially made by Ultimate Ear to protect his hearing and to ensure that he can communicate with Mission Control.

Bloodhound has a highly specialised windscreen custom-made by PPA Group from acrylic. The plastic is heated, stretched and then two layers are bonded together to create a 25mm section, thicker than a fighter jet’s windscreen and sufficient to withstand an impact with a 1kg bird at 900mph (1,448km/h). Due to the oblique angle the windscreen is set at, the driver will in fact be looking through 50mm of curved plastic. The key challenge has therefore been to make the screen robust while maintaining absolute visual clarity. Andy has drawn on his experience of flying fast jets and driving World Land Speed Record winners Thrust SSC and JCB Dieselmax to design the dashboard and cockpit layout. Good ergonomics are vital given that Bloodhound SSC will cover a mile in 3.6 seconds, or 150m in the (300 millisecond) blink of an eye.

The central screen shows the speed in miles per hour and Mach number (Mach 1 being the speed of sound), calculated by GPS, plus jet engine and rocket outputs. Dynamic speed indicators help Andy to judge when to fire the rocket and deploy the braking systems. Wheel loads are also given prominence. Bloodhound does not use aerodynamic downforce, as a Formula 1 car does, while lift at the nose or rear axle must also be avoided at all costs. The need to carefully balance forces throughout its 1000mph speed range is one of the major reasons why shaping the Car has taken 30 design-years.

The left-hand screen shows hydraulic pressures and temperatures in the braking and airbrake systems, while the one to Andy’s right provides information about the three engines, including temperatures, pressures and fuel levels. Together, the EJ200 jet engine and Nammo hybrid rockets produce around 210 kN (21 tonnes) of thrust, equivalent to 135,000 thrust hp, or 180 F1 cars, and Andy will monitor their status at key points during each run.

Bloodhound’s dash also features two precision-engineered analogue Rolex instruments: a chronograph with built-in stopwatch, and a speedometer graduated up to 1,100mph (1,770km/h). The speedometer is a vital back-up to allow the car to be stopped safely should the digital dashboard fail, while the chronograph will help to time the start-up and cool-down of the jet, and help to monitor the performance of other systems. Tested to withstand the severe vibration at 1,000 mph and the desert heat, these bespoke Rolex instruments are unique to Bloodhound SSC.

Andy enters his office via a carbon fibre hatch, 500mm in diameter, just below the jet air intake. At full power, the EJ200 fan sucks in 65 m3 of air per second, so the hatch will be fastened using latches able to withstand loads of 2.5kN (quarter of a tonne) to prevent it from getting ingested into the engine.

The instrument panels have been coated with a special non-reflective grey paint to provide the optimum background colour against which to see the gauges and controls, while the cockpit walls are white to maximise the available light in the cockpit. The Car also has interior lights, as Bloodhound SSC will often be prepared before dawn, when the desert will still be dark and temperatures around freezing.  During the day ambient temperatures will approach 40ºC (104ºF) though Bloodhound SSC will most likely not run in conditions above 25ºC (77ºF) as the metallic sections of the car will get too hot for the team to handle and the jet engine is inefficient when burning hot, less dense air.  Cockpit temperature is still expected to approach exceed 35ºC (95ºF), so external air conditioning will be used to cool it prior to each run, though this is primarily for the comfort of the electronics, not the driver.

Andy will keep Bloodhound SSC on course using a bespoke 3D printed titanium steering wheel, shaped to his hands and finger reach.  Buttons on the front control the EMCOM radio, airbrakes and parachutes, while triggers on the rear of the handgrips prime and fire the rockets.  BLOODHOUND engineers developed several design evolutions of the wheel, the last of which was finalised for manufacture by Cambridge Design Partnership. Bloodhound has a conventional steering rack with a 30:1 ratio (compared to a normal car of around 15:1) though its long wheelbase makes for a very large turning circle: 240 metres, compared with 10 metres for a typical family hatchback.

Bloodhound SSC has pedals like a regular car, though once again, they are custom designed for Andy. The right-hand pedal throttles the EJ200 jet engine and will be used to start the car moving. The left pedal controls the wheel brakes and will be used to slow the car at speeds below 200mph (321km/h). The wheel brakes will only contribute about one percent of the total braking effort, reducing the stopping distance by around half a mile.  Braking speed is critical, as using the wheel brakes above 200mph (321km/h) will exceed their energy capacity and set fire to them.

Driver safety has been the prime design and engineering objective throughout Bloodhound’s gestation and the team has worked closely with motor racing’s governing world body, the Fédération Internationale de L’Automobile (FIA) to create the best safety cell in the history of motor sport.