In the attempt to break the 1000mph land speed record, Bloodhound SSC has grown a split personality, never quite sure if it's a car, plane or even a power drill. Progress has been made with the project since we last spoke to them, with the two halves of the chassis now complete, along with the cockpit. I visited the Bristol Technical Centre to view the 'car' and talk to its fearless 'driver', Andy Green.
Arriving at the Bloodhound SSC Technical centre in Bristol, you're reminded of the area's aviation history as the unit is directly opposite the old Westland Helicopter factory. The Lynx Helicopter was made there, and is itself a speed record holder. Given Thrust SSC, the Bloodhound's forebear, was produced in the same unit, there must be something in the water around there.
Inside their anonymous unit, a dedicated team hired from the previous Thrust SSC project, Motorsport and Aviation are designing, machining and assembling this unique car. Funded by major brands such as Rolex and the 1K club, supporters get even greater access to the development of the project. Support also come from British universities -- Swansea University researched potential sites where the car will make its record breaking run, for example. Just about every flat surface around the globe was checked before Hakskeenpan in the South African Desert was selected. Bloodhound will run there in 2015 and again in 2016 in the process of getting up to the 1000mph record.
To reach this speed the car will need to break the sound barrier and keep accelerating. To achieve a speed that no aircraft is yet able to reach at this altitude (aircraft fly at altitude where the air is thinner, for less drag) Bloodhound needs as Jeremy Clarkson puts it, power! So the vehicle has three engines, with each engine taken from a different engineering discipline -- space, jet fighters and race cars.
Starting with a jet engine taken from the RAF's Eurofighter Typhoon, alone it provides 60Kn of thrust -- or, 40,000hp.
This is then joined at higher speeds by a solid fuel rocket. Burning rubber as the fuel, it will produce an incredible 123Kn of thrust.
So where does the third engine come into play? A V12 race car engine providing 700hp does not directly drive the car at all; instead it's attached to a pump, to feed the liquid HTP oxidiser through a catalyst into the solid fuel rocket. The HTP is used in order to provide the oxygen to burn the rubber solid fuel, with some 1000l of it being stored in a tank. Incredibly, this huge volume of liquid will be emptied by the pump in just 17 seconds.
Half Car, Half Plane
Housing these engines is the chassis, which is as greater dichotomy of technology as the engine set-up. To qualify for a land speed record this must be a car, thus its needs wheels and a driver. But its concept goes well beyond known car designs; it is literally half car, half plane. The split between the two halves is just behind the jet air inlet.
The rear half is almost entirely aircraft technology. The chassis made from CNC Machined aluminium bulkheads and stringers, with a titanium skin bonded and riveted to it. The drilling, counter sinking and riveting of the skin to the chassis is a skilled and labour-intensive job. Fortunately the Bloodhound team is supported by the Army's Royal Electrical & Mechanical Engineering Regiment. Their engineers, more used to servicing Chinooks in Afghanistan, are seconded to the project and have undertaken a large proportion of the detail fitting and machining of the rear aircraft-like structure.
Inside this skeleton sits the jet engine and the rocket below it. Ahead of the rocket lies the racecar engine and pump, along with a large water tank to cool the engine in place of air-fed radiators for less aerodynamic drag.
Ahead of this, the driver and HTP fuel tank sit cocooned inside an F1-style carbon fibre monocoque. Albeit the safety cell is somewhat scaled up from its racing cousin. Carbon fibre has been used for its strength and ease of shaping, although separate bodywork will also form the front wheel arches and nose cone.
Finally Bloodhound has unveiled the cockpit design, where RAF Fighter Pilot Andy Green will sit and control the car on its high speed runs. As this is his domain, Green has been responsible for its design; everything has been done to meet his needs for each run. Bearing in mind the rest of the car's design, it is again a mix of car and plane, with a bit of wrist watch and power tool mixed in.
With his seat, belts and race suit, Green will be very much in the mould of a racecar driver.
But the dashboard is far more jet fighter-like, with three LCD screens providing Green with the status of every system on the car. One display is very much like sat nav for the run. A vertical bar with coloured sections and flags shows him where he is on the run; when to fire the rocket, and when to deploy the parachutes, in order to get the run perfectly inline with predictions. Of course if these screens fail, he will need to gauge the speed he is travelling at in order to bring the car back safely to a halt. So Rolex has created a bespoke GPS Speedo for him, going from 0 to 1000mph, naturally.
There is also a matching Rolex Chronometer, as both record breaking runs must be completed within the hour.
Controlling the car and its engines are down to surprisingly conventional means. The jet engine is at the command of the left foot pedal and the right pedal controls the hydraulic brakes. (There's no clutch pedal on the Bloodhound.)
Steering is via an aircraft-style yoke control. Despite being over 13 metres long, the car will need a surprising amount of steering to keep it online during the run. For familiarity the aircraft yoke was chosen, and has been designed and moulded to Green's very own hands. To make the part, it was 3D printed in Titanium, then fettled to a perfectly smooth finish by Bloodhound's own engineers.
The yoke also houses the controls for the rocket, requiring a search for a button that can cope with heat and vibration. The response from the team's electrical department was a power drill, devices that provide on-off control under heat and vibration every day. Green was even invited to visit the local DIY store a pick one he liked. These have been integrated into finger triggers behind the hand grips.
Other cockpit controls include the safety cut off lever for the rocket and jet fuel, plus the parachute, which are all operated by the lever and cable arrangement.
Above his head is the carbon fibre canopy, looking like a post-war nuclear bomber. He will only need a clear view ahead, as the track is marked with a white line of vegetable dye to mark its centreline. But the reason for the solid canopy is its need to cope with shockwaves forming over the cockpit at supersonic speeds. With the car doing speeds of 1000mph, the jet engine still needs to ingest air at some 550mph, so the cockpit creates shockwaves to decelerate the air before entering the jet's inlet. Air going from 1000mph to 550mph in the space of a few meters is loud -- just check out this clip here.
Driving the Bloodhound, by Andy Green
"It all starts with 20 minutes of system checks. The race car engine is idling, the jet engine is idling. By now the canopy is sealed and probably quite warm in there and getting warmer, I don't mind as I'm concentrating.
Mission control is on the trailer, an RAF air traffic controller is in contact with all of the people involved -- in total, there are probably 40-50 different units around the desert.
I check the wind all the way down the track. We also have spotters all the way down the track. There's quite a lot of wildlife in South Africa; there's not much of it out in the desert, but it does come in some quite large packages. It doesn't matter how high the fence is, the nubuck here will jump a 4m high fence, so we won't be able to keep them out. Now, as long as they aren't on the track when I start, there is nothing fast enough on the planet to get in the way before I've gone past.
Recovery crews and rescue crews are ready, the 12m track is clear. I will call ready and I will get a clear to roll.
I'll lift off the brakes. Once it starts rolling forward it's initially quite sluggish. I'll wind the jet engine up to max turbine speed, as that's winding, then I'll get up to maximum reheat, that's up to nine tonnes of thrust.
Approaching 200mph I pull the trigger on the left of the steering wheel, this will then close the clutch between the race car engine and the HTP pump. It's just enough to heat up the catalyst pack, to get it up to 600c when it's generating oxygen. That will take 3-4 seconds; it will set light to the solid rocket fuel, that's effectively lighting the pilot light on the rocket.
I'm now waiting for the speed needles to reach the pink sector, which is the full power for the rocket needed to reach whatever speed we need before the measured mile. I squeeze the right hand trigger, and still have my foot flat on the jet. That's 9 tonnes of thrust and 12 tonnes of the thrust from the multipack rocket. The car will then start to accelerate at 2g, that's 40mph per second -- its going to be quite brisk.
It's marginally stable at max acceleration, if it's going to be unstable it's going to be at 300-400 mph.
I'm still following the 12m vegetable dye spray line down the desert. Approaching the measured mile simply marked by another line across the desert, that's 3.6s for the mile.
Then I release the triggers on the rocket that will shut it down, and throttle back on the jet. Then just the drag of the car will produce a 3g deceleration, so a 1000mph down to 940mph will take about a second, down to 880 will take a bit more than a second as the drag's already coming off.
Down to 800mph I start to crack open the airbrakes; they are scheduled to keep deceleration to about 3g. At about 650mph I'll pull a parachute out that will give another 8-9 tonnes of drag instantaneously that will be a snap 1.5g. That will slow the car to about 200mph, which is wheel brake speed with about 1m to go to the end of the run."