transport statistics


Test-firing of the Bloodhound SSC rocket engine in a live streamed data collection run


Going places A


From rocket testing to rapid transport systems,


Felix Grant investigates statistics and data analysis


in transport


s a child I lived, for a while, on open plains where (like all my schoolmates) I was fascinated by glimpses of how transport might


be in our future. Te P1127 (an experimental VSTOL aircraſt that would later become the Harrier); the Belvedere (a twin rotor helicopter, already aging and soon to be swept away by the Chinook); and, most exciting of all, something which we heard but never saw. Tis gave rise to one of my earliest serious


data gathering and analysis projects: a notebook in which I religiously recorded details of everything mechanical that moved and, with particular attention to detail, involved rocket test firings. Te date, time and direction for every roaring launch, every thud of a concrete warhead returned to earth, went into my little book. Aſter a while, though I didn’t know the term


‘data analysis’, I was able to tell my friends with fair accuracy when the next launch was likely to be, how long the flight would take and where the impact would probably be. Tese rockets had mysterious names like Honest John, Tor, Tunderbird and


www.scientific-computing.com


Bloodhound. Fiſty or so years on, another rocket bears the Bloodhound name, but without the warlike aura. Tis one aims to transport a human being, not an explosive charge, in an attempt upon both the land and low-level aviation speed records at 1.4 times the sea level speed of sound. At the same time, it is generating data and methods for spin-off into wider scientific and technological theatres, and scientific computing is at its heart. Te Bloodhound missile was, strictly


speaking, not a rocket at all. Its flight was powered by two ramjets, but rocket boosters were used to generate the initial airspeed necessary for those ramjets to ignite. Te new bloodhound also uses multiple engines, but here the relationship is reversed: the rocket provides the primary propulsion, with a jet engine serving as the initial accelerator. Te jet engine is one designed for the Eurofighter; and


One-off


‘This car is a one-off; the time and resources in any other project of this magnitude would require many people and be many times the cost. MathWorks gives us the tools that allow us to rapidly prototype the design with fewer resources. One of the biggest benefits is the fact we can do hardware in loop testing – this is invaluable in the timescale we have got, and it probably would not be possible without it.’ Joe Holsworthy, Bloodhound systems engineer


the rocket is a hybrid design, burning synthetic rubber solid fuel with a liquid HTP (high test peroxide) oxidiser reacting with a fine silver mesh catalyst. Tere is also a third engine, designed for Formula One racing cars, which serves as a fuel pump delivering the HTP to the rocket at the required pressure (more than five and a half million Pascals). All of this (even without other components


such as a custom-designed gearbox) adds up to what Coorous Mohtadi of MathWorks summarises as an ‘extremely harsh environment with a mixture of technologies in close proximity, which would under any other circumstances probably not be combined.’ Well-known soſtware names are found throughout the Bloodhound SSC literature, and MathWorks is prominent. A complex set-up means data collection is


highly stressed. Every component is operating in unknown conditions, placing existing manufacturer and operator data outside useful bounds – Rolls Royce, for instance, has accumulated plenty of data on the jet engine, but in an aircraſt where none of Bloodhound’s complex ground and interactive thrust vibration patterns would have existed. Te data gathering is essential to


performance optimisation, but configurability requirements not present in the original roles of the components render normal redundancy insurance measures impossible. Collection is at one millisecond resolution; remember that at maximum car speed that represents roughly half a metre displacement, with everything controlled by a human driver’s reactions. Each


DECEMBER 2012/JANUARY 2013 9


Olympus


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