Final countdown: the supersonic cockpit of the land speed racing car bloodhound SSC has finally been unveiled, as an all-out assault on the 1,000 mph record draws ever closer through the eyes of driver andy green, editor brian wall gets an inside view.
Using five types of carbon fibre weave and two different resins, the monocoque, handcrafted by URT Group, has taken more than 10,000 hours to design and manufacture. Sandwiched between the layers of carbon fibre are three varying thicknesses of aluminium honeycomb core (8, 12 and 20mm), which provide additional strength. At its thickest point, the monocoque comprises 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 I ,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 in excess of 1,000mph 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 sound levels expected in and around BLOODHOUND SSC are being carefully evaluated. 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 outrun its own sound waves. However, the project's engineers still anticipate that shockwave and jet intake noise levels may produce more than 120 decibels inside the cockpit. Andy Green 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 SSC also 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 Ikg bird at 900mph (1 ,448km/h). Due to the oblique angle the windscreen is set at, the driver will be looking through 50mm of curved plastic. The key challenge has therefore been to make the screen robust, while maintaining absolute visual clarity.
ndy Green 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 I being the speed of sound), calculated by GPS, plus jet engine and rocket outputs. Dynamic speed indicators help him judge when to fire the rocket and deploy the braking systems. Wheel loads are also given prominence. BLOODHOUND SSC does not use aerodynamic downforce, as a Formula I 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.
Inside Andy's 'office', the left-hand screen shows hydraulic pressures and temperatures in the braking and airbrake systems, while the one to his right provides information about the three engines, including temperatures, pressures and fuel levels. Together, the EJ200 jet engine and Nammo hybrid rockets produce around 2 10 kN (21 tonnes) of thrust, equivalent to 135,000 thrust hp, or 180 F I cars, and Andy will monitor their status at key points during each run. BLOODHOUND SSC's dash also features two precision-engineered analogue Rolex instruments: a chronograph with built-in stopwatch, and a speedometer graduated up to 1, I 00mph (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 time the start-up and cool-down of the jet, and help monitor performance of other systems. Tested to withstand both the severe vibration at 1,000 mph and desert heat, these bespoke Rolex instruments are unique to BLOODHOUND SSC.
LIGHTING THE WAY
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 65m3 of air per second, so the hatch willsixbe 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 coloured white to maximise the available light within.
The car also boasts interior lights, as BLOODHOUND SSC will often be prepared before dawn, when the desert is still dark and temperatures are around freezing. During the day, ambient temperatures will approach 40[degrees]C ( I 04[degrees]F), though BLOODHOUND SSC will most likely not run in conditions above 25[degrees]C (77[degrees]F), 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 35[degrees]C (95[degrees]F), 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 SSC engineers developed several design evolutions of the wheel, the last of which was finalised for manufacture by Cambridge Design Partnership, BLOODHOUND SSC has a conventional steering rack, with a 30: I ratio (compared to a normal car of around I 5: I), though its long wheelbase makes for a very large turning circle: 240 metres, compared with 10 metres for a typical family hatchback.
The cockpit is also a showcase for the extraordinary skills of UK manufacturing. The BLOODHOUND SSC Project is being supported by a whole raft of world-class companies that share its ambition to inspire a generation to follow science and engineering--by building, and racing, the most extraordinary car in the world.
Over to Andy Green: "It was great to see the cockpit finished and unveiled in public. This is my 1 ,000mph office', which 1 first started to design over six years ago. The design approach for the cockpit was a simple one. I need to see over the nose [so he knows where he's going!], so that fixes my eye height. With large acceleration and deceleration forces, I want to sit as upright as possible, so the seat sits right down on the cockpit floor. The centre cockpit display screen needs to be just below my eye line, so I can easily scan between the track and the speedometer etc. The steering wheel needs to be low enough to see the screens over it. My legs need to be fairly straight, to keep clear of the bottom of the steering wheel, so the pedal box is as far forward as possible, while the seat is as far back as possible.
"Five years ago, we built a cockpit mockup to make sure that everything would fit. Once the mould for the cockpit outer shell (the carbon fibre 'monocoque') was complete, we made a second mock-up from this mould to refine the position of the seat, windscreen, instrument panels and so on. Then the huge load-bearing sills inside the cockpit were added, reducing the room for instrument panels.
"The internal handle over my head for the cockpit hatch was added, reducing the headroom available. The rear cockpit bulkhead grew a 'bulge' to fit the huge HTP tank fitted just behind the cockpit.
"All of this was drawn in the 3D computer model and appeared to fit--just--but there's only one way to be sure. Hence my relief ... when it all came together and showed that it all does fit--just."
To make that easier to understand, just take a look at the amazing BLOODHOUND SSC video tour of the controls by going to: http://www.bloodhoundssc.com/news/\inside-andy-greens-1000mph-office.
And also the 360 degree photo view of the cockpit at: http://www.bloodhoundssc.conn/cockpit360.
The cockpit will also be the centre for the world's fastest outside broadcast studio. "Our long-term goal is to bring science and technology to life for a new generation of young engineers," states Andy Green.
"To do that, we're going to stream live in-cockpit video, and technical data, through the internet every time we run BLOODHOUND SSC. The aim is that, wherever you are in the world, you can watch exactly what we're doing, live."
The key to streaming live video from a car doing 1,000 plus mph, for the first time in history, is the new MTN mast network surrounding the track on Hakskeen Pan, in the Northern Cape of South Africa, which means sharing the experience with what will no doubt be a massive global audience.
Another major step forward recently for BLOODHOUND SSC was the spin test of the desert wheel. The wheel is a solid aluminium disc, about 91 cm in diameter and weighing some 95 kg. At maximum speed, the wheel will spin at over 10,000 rpm--170 times per second--and the wheel rims will experience an outward acceleration of 50,000 times the force of gravity. 50,000 radial 'G' is why they are made from solid forged aluminium, as there is no tyre in the world that can survive that kind of load.
The wheels were forged by Otto Fuchs last year (if you haven't seen it already, have a look at the video, it's truly fascinating--http://www.bloodhoundssc.com/news/fastest-wheels-history).
"These incredibly strong discs, known as 'cheeses', are then machined by Castle Precision to the very precise shape that Lockheed Martin (UK) helped us to develop," explains Green.
"All well and good, but at high speeds the wheels are safety critical, so how can we prove that this unique design will cope? Step forward Rolls-Royce, who gave us the use of their engine spin test rig.
"We spun the wheels to 10,496 rpm. Strange things happen at these speeds. The wheel grows very slightly under the 50,000 G load (it was this growth that we were measuring). It also gets quite warm. Above 6,000 rpm, the wheel was heating up by one degree per second, peaking at 92 degrees C. The good news is that wheel behaved exactly as we expected, so it passed the test." So, huge relief all round!
With the wheel shape proven, Castle can manufacture the rest of the desert wheels for 2015. "All we need now is the rest of the car to bolt them to and that's coming along very nicely," Andy reports.
Cockpit apart, the upper chassis panels are all but complete. "Timken has supplied all the steel wheel bearings [3 per wheel, in matched sets] for our runway tests, we've received all 200 plus bits for the airbrake systems, the jet engine fuel tank, a marvel of carbon fibre complexity, has been delivered and vehicle assembly is pressing ahead," he states. The countdown is gathering pace."Next year's test runs are starting to feel closer all the time."
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|Date:||Sep 1, 2014|
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