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Andy Green Diary: The desert wheel

A British team is developing a car that will be capable of reaching 1000mp/h - 1610km/h. Powered by a Eurofighter-Typhoon jet engine the vehicle will try to crack the world land-speed record. It's called Bloodhound and wheels24 has been tracking development.

"Data is key to pushing the boundaries – work out what you need and build it in from the start." That was the advice we got from former Nasa astronaut Neil Armstrong when he visited the Bloodhound technical centre in Bristol, UK  in 2010.

This was our plan, but it was great to hear it confirmed by the first man to walk on the Moon. The reality seemed a long way off at the time, but suddenly it’s here and we’re building the sensors into Bloodhound SSC.

400 HIGH-SPEED SENSORS

The plan for the whole car involves around 400 high-speed sensors, measuring everything from air pressure (in over 100 places, to validate our airflow modelling), through to structural loads, and even my heart rate while I’m driving at 1000 mph (I voted against this one and lost). Each one of these sensors will be recorded at 500 Hertz (500 times a second) so we can analyse the data in detail.

At peak speed in Bloodhound SSC the air will be tearing past at 450 metres per second so working out what happens on each run will be vital. It was this sort of approach that got Armstrong to the Moon in 1969. Our previous world record in 1997 when Thrust SSC went supersonic was the first time this sort of data-intensive approach had been used for record-breaking.

The technology was more basic with over 100 sensors measuring temperatures, pressures and load at only 80 Hertz or less. That was enough for us to be able to keep the car safely on the ground, and to set the first supersonic world land-speed record.

Data helps with more than just keeping the car on the ground. The straight-line performance of the car – in other words, how fast it will go – can also be determined from the data. Since this is the whole aim of the world land-speed record it’s important stuff. But it’s more even than that.

Our performance expert Ron Ayers has spent more than 20 years analysing performance data from every available source, going back to the 1920s. As a result I believe he can predict more accurately than anyone alive just how fast a Land Speed Car will go, and how long it will take to stop.

It’s Ron’s huge expertise, honed during the Thrust SSC project, which gives us the confidence that we can reach the astonishing speed of 1000 mph. His performance programme is based around a calculation spreadsheet 100 columns across and well over 1000 lines deep.

At this point you may be harbouring a small ‘so what?’ Why does it matter where we stop? The reason is in the rules for the world land speed record. In order to set a record, you have to do two runs within 60 minutes.

DESERT WHEELS


For Bloodhound, that means doing a racing pit-stop on something as complicated as the space shuttle. Stopping a mile or two from the right place will cost time which puts the crew under huge pressure to hurry, which isn’t safe when you’re getting ready to do 1000 mph. Something as simple as stopping the right place can make my job a lot safer.
 
This is a safety-critical part of the car as it will be subject to huge pressures at 1000 mph (around 1.7 bar), which will exert a ‘bursting load’ on the intake of around 29 tonnes. If the intake bursts, then it will take the upper bodywork with it, which could then leave me poorly placed. To make sure that the intake is up to the job, we’re going to pressure-test it.

As we inflate a huge air bag inside the intake, the strain gauges will measure the movement (or ‘strain’) in the carbon-fibre structure. This will confirm that it can cope with the full 1000 mph load, and more. These strain gauges will remain in place for the life of the car, so that we can monitor structural health at every stage of its life.

At the Bloodhound technical centre I finalised the details of the drag parachute system, which will undergo final testing before we fit the first system into the car. While I was there, we had a delivery – the first desert wheel has arrived.

The 95kg disk will spin at around 10 200 times a minute 170 times per second at 1000 mph, subjecting it to loads of 50 000 times the force of gravity. Rolls-Royce is going to spin the wheel on its old engine test rig and, as you would expect, we’ll fit it with instruments. This will validate all of our computer modeling and prove that the wheel will cope at more than 1000mph.

Until next time, cheers, Andy
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