Under pressure to break the land speed record

| Environmental Testing

The Bloodhound LSR car combines engineering skills and innovation to prepare for its attempt on the land speed record

Environmental test and measurement technology is playing a leading role in breaking new land speed records

The Bloodhound Land Speed Record (LSR) could be one of the great engineering achievements for the UK in the new decade. Years of design, preparation and stretching engineering disciplines to their limits have resulted in a successful set of tests that pave the way to a record breaking run that is scheduled to take place in Autumn in 2021.

The current Land Speed Record is held by Andy Green, who piloted Thrust SSC to 763mph (1227kph) in 1997. Green is part of the Bloodhound LSR project and expects not only to break his existing record, but also to follow up with a run topping 1000mph.

The latest testing that’s been performed with Bloodhound LSR took place in October and November 2019 at Hakskeenpan in Northern Cape, South Africa. There, the car reached first of all 500mph then 628mph, easily achieving the targets set for these crucial tests.

Engineering Trials

The testing in South Africa took place to prove the engineering integrity of the build and compare actual performance to that, which had been modelled. After an initial run at just 100mph to test the control functions, the vehicle’s engineering was stretched at higher speed runs. These high speed test runs were carried out using a Eurojet EJ200 jet engine but for the record run, a Nammo rocket engine will be used.

According to the Bloodhound LSR team, the project is a showcase of engineering at its very best. To break the record, absolute precisions is required in every aspect of what is done, starting with the design and then in the manufacture and assembly of the car.

The testing in South Africa needed to prove that the driver is able to control the car with extreme accuracy and immediate response as there is no room for error at such high speeds.

Additionally, engineers were able to gather a whole range of key data about the car, plus other information needed to plan everything related to the record-breaking runs next year. This includes how the wheels interact with the desert, validation of the computational fluid dynamics (CFD) models and testing the parachutes.

It was important in the tests so see how the car behaves when slowing down and stopping from a number of target speeds, building up to and beyond 500 mph (800 km/h) in each run by increments of 50 mph (80 km/h).

The team examined how much drag the car creates in a number of scenarios and at various speeds, using the wheel brakes, one or both of the drag parachutes, and with the giant airbrakes locked into position.

Pressure Measurement

An understanding of the all-important aerodynamic performance of the car is crucial in achieving the new land speed record. The Bloodhound LSR team enlisted the help of UK measurement specialist, Evolution Measurement and their principal, Scanivalve, to provide pressure measurement expertise.

Assistant Aerospace Engineering Professor Ben Evans from Swansea University and PhD student Jack Townsend joined the Bloodhound team in the desert to help analyse the gigabytes of performance data from each of the runs.

They were able to monitor the data from 192 pressure sensors on the car and compare the real data against the predicted Computational Fluid Dynamics (CFD) models to see how closely they marry up, an exercise that was designed to reveal the amount of drag experienced by the car on each run.

A key aim of these tests is to provide valuable data allowing the refinement of the CFD models, which will in turn improve the accuracy of future modelling. Bloodhound engineers will use the data to validate the next run profile, allowing safe increments in speed as the real vehicle data is compared with its ‘digital twin’.

The data will also help determine the size of the rocket that will be fitted to the car for the attempt to set a new world land speed record in autumn 2021.

Evolution Measurement Managing Director, Paul Crowhurst said, “We are excited to be a part of engineering history. This is an amazing project and we were delighted that our partners at Scanivalve Corp were able to support the team with the technology.

According to Addison Pemberton of Scanivalve Corp, the pressure measurement instrumentation donated to the project was used to survey aerodynamic down forces on the vehicle to ensure safe operation at these very high speeds.

The ZOC pressure scanner can withstand brutal test environments and its use on this project demonstrate its strength and capability in delivering valuable data in extremely harsh conditions.

High Correlation

After the tests, Evans and Townsend found there was a 90% correlation between the real-world data and models generated before the runs using computational fluid dynamics (CFD).

Now, the remaining 10% of the data is being studied to refine the predictions and strengthen the team’s knowledge of transonic airflow. However, the otherwise high level of correlation has given the Bloodhound team great confidence in the aerodynamic shape of the car and confirmed plans to fit winglets to the tail fin to manage the vertical downloads on the rear wheels.

The data has also confirmed the drag the car experienced at transonic speeds. Crucially, this indicates the power needed from the rocket to propel the car through the sound barrier (approximately 760mph, 340m/s) and into the record books. The data shows a 50-60kN monopropellant rocket is required.

Engineering Showcase

A key element of the latest land speed record attempt is to showcase the engineering capabilities required to push new boundaries and to encourage young people to take up careers in STEM (Science, Technology, Engineering & Mathematics) subjects.

According to the Bloodhound LSR team, the project is helping to push boundaries and demonstrate pioneering new technologies with many aspects of the car having required engineers to think in new ways and manufacturers to develop novel production and testing methods.

Already, there have been many spin-offs from the project, including technology development, pushing the limits of materials science, validation and improvement of computational models.

Commenting on this aspect of the project, Ian Warhurst, CEO of the car’s owner Grafton LSR Limited, states that the project has inspired so many people over the last 10 years, including both students and the wider engineering community.

“Engineers like solving problems and theorising about what happens when you pass the limits of known understanding. We look forward to continuing this inspiration into the future,” he concludes.

Zero-Emission Rocket

For the world land speed record challenge, the Bloodhound LSR team has chosen a zero-emissions rocket. Powered by concentrated hydrogen peroxide, the rocket will be used alongside the world’s best jet-fighter engine when the car attempts to reach speeds beyond 800mph in South Africa in the third quarter of 2021.

Nowegian company, Nammo has designed a compact, zero-emissions rocket to be used as a launch motor to put small satellites into space. The size and power of this rocket makes it ideal for use in Bloodhound LSR.

The Nammo rocket is a ‘monopropellant’ design that uses concentrated hydrogen peroxide (water with an extra oxygen molecule – H2O2) as the oxidiser. This is pumped at high pressure through silver gauze, which acts as a catalyst, causing it to decompose into super-heated steam (600°C) and oxygen. The steam and oxygen are channelled through a nozzle to generate thrust. There is no fuel ‘combustion’ and therefore no flame nor any chemically harmful waste generated by the rocket from each run. Bloodhound LSR will be steam powered!

Work is also underway to optimise the auxiliary power unit needed to pump the rocket’s oxidiser. Rather than the originally specified 550bhp V8 internal combustion engine, this will be an electric motor and battery pack of comparable power, using technology only available very recently.

The Bloodhound team is also exploring the possibility of running the Rolls-Royce EJ200 jet engine on bio-fuel instead of Jet A fuel, further reducing the environmental impact of operating the car.

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