tag:theconversation.com,2011:/africa/topics/land-speed-record-10262/articlesLand speed record – The Conversation2019-08-28T20:01:47Ztag:theconversation.com,2011:article/1223212019-08-28T20:01:47Z2019-08-28T20:01:47ZHow fast can a human cycle? With aerodynamic help, the 300km per hour barrier seems easily within reach<figure><img src="https://images.theconversation.com/files/289793/original/file-20190828-184234-1xoqopx.png?ixlib=rb-1.1.0&rect=3%2C0%2C829%2C435&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">With aerodynamics out of the equation, it's possible to go really, really fast.</span> <span class="attribution"><span class="source">YouTube/Euronews</span></span></figcaption></figure><p>British cyclist Neil Campbell <a href="https://www.bbc.com/news/uk-england-essex-49393888">recently set a new record</a> for the men’s “fastest bicycle in a slipstream”, clocking up a breathtaking 280km per hour. </p>
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<figcaption><span class="caption">Neil Campbell’s record-breaking performance.</span></figcaption>
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<p>This record involves bringing a cyclist up to speed in the wake of a towing vehicle, then releasing the bike and timing the rider over a 200m distance. The overall record stands at 296km per hour, <a href="https://www.guinnessworldrecords.com/world-records/426619-fastest-bicycle-speed-in-slipstream-female">set in September 2018 by Denise Mueller-Korenek</a>, who was towed by a dragster on Utah’s Bonneville Salt Flats.</p>
<p>But just how much can these high cycling speeds can be attributed to human performance? Does it take a supreme athlete to maintain that speed after release, or is the vehicle really doing all the hard work? And if so, does that mean even faster records are possible? </p>
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Read more:
<a href="https://theconversation.com/yes-there-is-a-limit-to-athletic-ability-physics-8343">Yes, there is a limit to athletic ability – physics</a>
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<p>By considering the energy supply and demand involved in Campbell’s new men’s record, we can begin to appreciate the relative contributions from human and machine. For this record, energy comes from both the car’s fuel combustion and from human power. </p>
<p>The power required to maintain a given speed depends on the resistive force acting against the rider’s forward motion. On a flat course at a constant speed, there are two key components:</p>
<ul>
<li><strong>aerodynamic resistance</strong>, also known as aerodynamic drag </li>
<li><strong>rolling resistance</strong>, which broadly covers the friction between wheels and road, the friction in the wheel bearings, and the efficiency of power transmission from the pedals through the chain to the wheels. </li>
</ul>
<p>Crucially, aerodynamic resistance <a href="https://www.cambridge.org/core/journals/journal-of-fluid-mechanics/article/drag-kings-characterizing-largescale-flows-in-cycling-aerodynamics/1E4A39549041D3A8F9C9033BC269C5D0">increases with the square of air speed</a>, which means it increases very rapidly as the speed increases. Rolling resistance, meanwhile, increases linearly with speed, which means it increases much less rapidly as speed rises.</p>
<p>Benjamin Thiele, lead systems engineer of the Monash Human Power Team at Monash University, explains it like this:</p>
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<p>Basically, if you want to cycle fast and you had the option to exclude one of the resistive forces from the physics, you would be wise to remove the aerodynamic component. </p>
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<p>To put this in context, in elite level track cycling (where there are obviously no cars to hide behind!), aerodynamic drag typically accounts for <a href="https://journals.humankinetics.com/view/journals/jab/14/3/article-p276.xml">about 95% of the total resistive force</a>.</p>
<p>Thus the towing vehicle in Campbell’s record attempt helped him in two crucial ways. First, it brought him up to speed, thus reducing his energy expenditure during acceleration. </p>
<p>Second, the car’s slipstream attachment (basically a cross between a spoiler and a tent, behind which Campbell positioned himself during the ride) removed much of the aerodynamic resistance that would otherwise become insurmountable at such dizzying speeds.</p>
<p>By riding in the vehicle’s wake, the rider will experience both low relative wind speeds and low aerodynamic resistance. In fact, if the rider is positioned correctly, the air flow in the car’s wake can actually generate a <a href="https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930091542.pdf">propulsive aerodynamic force</a> – effectively, the vehicle “drags” some air behind it, and the rider can thus be sucked along with it.</p>
<p>What about the physical demands of maintaining that speed after the tow release? This primarily depends on the size of the gear being used, and of the rolling resistance that needs to be overcome. By my calculations, and assuming aerodynamic drag behind the tow car is negligible, hitting 300km per hour (the next big milestone for both the mens’ and womens’ slipstream records) would require the rider to maintain a power output of 600-700 watts for the 2.4 seconds it would take to ride through the 200m time trap.</p>
<p>This seems achievable enough, given Tour de France riders can put out more than 1,000W for a <a href="https://www.cyclingweekly.com/news/racing/data-reveals-the-most-powerful-sprints-of-2018-and-the-numbers-are-pretty-mind-blowing-359140">full minute or more</a>.</p>
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Read more:
<a href="https://theconversation.com/the-aerodynamics-of-a-tour-de-france-time-trial-29568">The aerodynamics of a Tour de France time trial</a>
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<p>So the tow vehicle is really the crucial factor, rather than the rider’s physical performance. In fact, if the rider were to pull out of the slipstream after being towed up to 300km per hour, the energy demand to maintain this speed would be on the order of 100 kilowatts – roughly the performance of a high-powered motorcycle!</p>
<h2>What about unassisted cycling records?</h2>
<p>Given the crucial importance of overcoming aerodynamic drag, it’s no surprise elite cycling teams invest so much into <a href="https://link.springer.com/article/10.1007/s12283-017-0234-1">aerodynamics research and development</a>.</p>
<p>In fact, the aerodynamics of conventional bicycles and riding positions are far from optimal. This is evident when we compare speeds achieved on conventional bicycles with those of a “faired recumbent human-powered vehicle”. This is a modified bicycle on which the rider lies down in a recumbent position, with the pedals at the front, inside an aerodynamic covering called a fairing.</p>
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<a href="https://images.theconversation.com/files/289736/original/file-20190828-184229-kma0y6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/289736/original/file-20190828-184229-kma0y6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/289736/original/file-20190828-184229-kma0y6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/289736/original/file-20190828-184229-kma0y6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/289736/original/file-20190828-184229-kma0y6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/289736/original/file-20190828-184229-kma0y6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=753&fit=crop&dpr=1 754w, https://images.theconversation.com/files/289736/original/file-20190828-184229-kma0y6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=753&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/289736/original/file-20190828-184229-kma0y6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=753&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">A faired recumbent bicycle designed, developed and manufactured by Monash University students.</span>
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<p>The speed record for such a vehicle over a 200m distance currently stands at <a href="https://www.popularmechanics.com/technology/a22946/human-powered-speed-record-aerovelo/">144km per hour</a>. This is about twice as fast as peak speeds achieved during velodrome sprints on a conventional track bicycle. </p>
<p>David Burton, manager of Monash University’s <a href="https://www.monash.edu/research/infrastructure/platforms-pages/wind-tunnel">wind tunnel research facility</a>, says elite cycling has “already exhausted the low-hanging fruit when it comes to gaining a competitive advantage through aerodynamics”, given the rules and constraints of the sport in terms of equipment design and rider position. </p>
<p>But he adds there are still some high-tech research avenues to improving performance, including “advanced experimental testing techniques and highly resolved numerical simulations of the flow fields around cyclists”.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/289738/original/file-20190828-184234-1xopel6.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/289738/original/file-20190828-184234-1xopel6.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/289738/original/file-20190828-184234-1xopel6.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=231&fit=crop&dpr=1 600w, https://images.theconversation.com/files/289738/original/file-20190828-184234-1xopel6.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=231&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/289738/original/file-20190828-184234-1xopel6.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=231&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/289738/original/file-20190828-184234-1xopel6.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=290&fit=crop&dpr=1 754w, https://images.theconversation.com/files/289738/original/file-20190828-184234-1xopel6.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=290&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/289738/original/file-20190828-184234-1xopel6.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=290&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Experimental and numerical techniques being employed by researchers at Monash University, The Australian Institute of Sport and Cycling Australia to optimise elite level cycling performance.</span>
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<p>As we have seen above, there is probably still the potential for even greater speeds when it comes to slipstream-assisted cycling. I suggest it’s within the realm of current elite-level human performance to achieve speeds approaching 400km per hour when enveloped in the wake of a vehicle.</p>
<p>Perhaps the challenge ultimately then becomes a psychological one: would anyone dare attempt it?</p><img src="https://counter.theconversation.com/content/122321/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Timothy Crouch does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>British cyclist Neil Campbell has set a new men’s speed record for slipstreaming behind a car. But his speed of 280km an hour, while breathtaking, has not taken human cycling performance to the limit.Timothy Crouch, Experimental Aerodynamicist, Monash UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/623062016-07-22T06:25:03Z2016-07-22T06:25:03ZHow to build a 1,000mph car (by the scientists behind it)<figure><img src="https://images.theconversation.com/files/130950/original/image-20160718-2150-1nahbsx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">BLOODHOUND SSC during construction at the Bloodhound Technical Centre, Avonmouth, summer 2015.</span> <span class="attribution"><span class="license">Author provided</span></span></figcaption></figure><p>It was a staggering feat, a car that went faster than the speed of sound. On October 15 1997, Andy Green travelled across the Black Rock Desert, Nevada, in the <a href="http://www.landspeedrecord.org/thrust-ssc-andy-green/">Thrust SSC at 763.035 mph, or Mach 1.02</a>. Two decades on, that record remains unchallenged. Until now.</p>
<p>Back in 2007, a small team of British engineers headed up by Richard Noble and Andy Green decided to have a pop at the world land speed record once more. This time, their sights were set on 1,000mph. A rocket scientist was brought in to design the largest hybrid rocket system ever developed in the UK, a structural engineer was brought in to design the car’s internal structure and I was invited to join the team along with Ron Ayers to ensure that this car would, indeed, remain a car and stay firmly planted on the ground. Ron and I would be responsible for the aerodynamic design of the car. It would be called <a href="http://www.bloodhoundssc.com">BLOODHOUND</a>.</p>
<p>I must confess that none of us anticipated back then that it would take quite so long to get to this point. Ambitious engineering projects, however, do have a habit of overrunning. This particular one, completely dependent on sponsorship and operating through a major global recession, has been no different. </p>
<h2>A leap of faith</h2>
<p>So, here we are. We have completed the extensive <a href="http://link.springer.com/article/10.1007/s00158-012-0826-0">seven-year design process</a>, including multiple <a href="https://www.researchgate.net/publication/303800132_Aerodynamic_optimisation_of_the_rear_wheel_fairing_of_the_land_speed_record_vehicle_BLOODHOUND_SSC">design iterations and optimisation cycles</a>.</p>
<p>We have built the car and revealed the real thing to the world. We have even practised the loading of the car onto the transporter plane soon to take us to our high speed test site on the Hakskeen Pan in South Africa.</p>
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<figcaption><span class="caption">Building BLOODHOUND in 90 seconds.</span></figcaption>
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<p>We have also recently signed a major new sponsorship deal which means that the funding is now in place to start the vehicle testing. We will finally discover whether or not all of our design and modelling work has been correct. This is the moment that the adventure gets real. Did we get it right?</p>
<p>You might be concerned that we are about to attempt a 1,000mph land speed record when all of our understanding of the car’s aerodynamic behaviour has been done using computer modelling – in a “virtual wind tunnel”. We have not done real world wind tunnel testing or rocket sled testing to double check our results. Bear in mind that if we’ve got this wrong then we could easily generate sufficient lift to project BLOODHOUND SSC skywards. Equally, too much downforce and we might find ourselves with the world’s fastest plough.</p>
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<img alt="" src="https://images.theconversation.com/files/131114/original/image-20160719-7913-rzsyxa.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/131114/original/image-20160719-7913-rzsyxa.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=445&fit=crop&dpr=1 600w, https://images.theconversation.com/files/131114/original/image-20160719-7913-rzsyxa.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=445&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/131114/original/image-20160719-7913-rzsyxa.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=445&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/131114/original/image-20160719-7913-rzsyxa.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=559&fit=crop&dpr=1 754w, https://images.theconversation.com/files/131114/original/image-20160719-7913-rzsyxa.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=559&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/131114/original/image-20160719-7913-rzsyxa.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=559&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">BLOODHOUND SSC design evolution from concept (config 0) through to final design (config 13).</span>
<span class="attribution"><span class="license">Author provided</span></span>
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<p>Back in the 1990s, when computer modelling was the primary tool for the aerodynamic design of Thrust SSC, extensive validation of the computer model was undertaken using a scaled model of the car strapped to a rocket sled. Comparison of data originating from the scaled rocket sled model and the computer predictions gave the Thrust SSC engineers the confidence they needed to press ahead and build the car.</p>
<p>This time we are doing things differently. Computational aerodynamic modelling has come so far in the last 20 years that this time around we will be using the car itself to <a href="http://onlinelibrary.wiley.com/doi/10.1002/num.20644/abstract">validate the computer model that was used to design it</a>.</p>
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<img alt="" src="https://images.theconversation.com/files/131115/original/image-20160719-8008-1btpgy3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/131115/original/image-20160719-8008-1btpgy3.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=296&fit=crop&dpr=1 600w, https://images.theconversation.com/files/131115/original/image-20160719-8008-1btpgy3.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=296&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/131115/original/image-20160719-8008-1btpgy3.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=296&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/131115/original/image-20160719-8008-1btpgy3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=372&fit=crop&dpr=1 754w, https://images.theconversation.com/files/131115/original/image-20160719-8008-1btpgy3.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=372&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/131115/original/image-20160719-8008-1btpgy3.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=372&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Computer model pressure predictions (Mach 1.3) and surface pressure sensor locations.</span>
<span class="attribution"><span class="license">Author provided</span></span>
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<p>But don’t worry, we won’t be heading out to our test site in South Africa and telling Andy to “put his foot down” straight away. Over the next couple of years, starting with “low speed” runway testing at Newquay’s AeroHub in Cornwall we will slowly be increasing the speed of our test runs. The surface of the car itself is covered with about 200 pressure sensors and data from these sensors will be compared with the computer model predictions that were used to design the car in the first place.</p>
<h2>Driving through the sound barrier</h2>
<p>One of my jobs after each run will be to check this mass of data and help decide whether or not we have the confidence in the computer model to try going a little faster on the next run. Of course, my hope will be that the computer model predictions and the car’s sensor data track neatly next to each other as we increase the car’s speed. But this is now the real world and there might be times when we have to (metaphorically) put on the brakes and ask ourselves some difficult questions. This, perhaps, will require us to tweak the computer model or even tweak the car’s design itself.</p>
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<figcaption><span class="caption">BLOODHOUND SSC testing date is announced.</span></figcaption>
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<p>And we want to keep everyone involved and engaged in this process. All of the data coming from the car’s sensors will be made available to the public after every run so that you can help us with this data analysis. We will be <a href="http://www.bloodhoundssc.com/bloodhound-tv">streaming the test runs live across the internet</a> so you can follow our progress every step of the way.</p>
<p>The adventure is certainly now getting very real indeed …</p><img src="https://counter.theconversation.com/content/62306/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ben Evans receives funding from RAEng, EPSRC and Fujitsu. He is affiliated with EESW (Engineering Education Scheme in Wales). </span></em></p>Preparing BLOODHOUND to break the world land speed record … and how you can take part.Ben Evans, Lecturer, Swansea UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/479762015-09-24T05:27:30Z2015-09-24T05:27:30ZHow to build the world’s fastest car<figure><img src="https://images.theconversation.com/files/95879/original/image-20150923-2652-1q65nz4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Flock/Bloodhound</span></span></figcaption></figure><p>In 2016, a team of engineers and adventurers will travel to the South African desert and attempt to become the first people to drive a car at 1,000mph. The British-made vehicle, <a href="http://www.bloodhoundssc.com">Bloodhound SSC</a>, is designed to smash the current world land-speed record of 763mph to become the fastest car ever built.</p>
<p>Amazingly, this incredible target isn’t even the project’s main goal. Breaking the land-speed record is nothing new for the UK, which has held the title for 79 of the past 100 years – and continuously for the last 32 years, most recently with [Thrust SSC](http://www.guinnessworldrecords.com/world-records/land-speed-(fastest-car), driven by Andy Green. But when Green, along with previous record holder Richard Noble and the then science minister Lord Drayson, <a href="http://www.bloodhoundssc.com/story">launched Bloodhound</a> in 2008, their aim was to inspire the next generation of problem solvers to put their great talent into science, technology, engineering and mathematics.</p>
<p>The other goal, of course, was to challenge the country’s engineers to complete a world-class research and development project. But how do you even start to design and build a car that is hundreds of miles an hour faster than any other the world has ever seen? There are three main things to consider. Is it slippery enough? Is it powerful enough? And is it strong enough? </p>
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<h2>The slippery subject of aerodynamics</h2>
<p>Anyone will know just from flying a kite that there is great power in the moving air. That’s fine if you are working with the airflow but with Bloodhound we will be trying to push against it faster than the speed of sound. Pushing an object through the air creates a tremendous amount of <a href="http://www.universetoday.com/73315/what-is-air-resistance/">resistance force</a> and the greater the frontal area of the object, the higher that resistance will be.</p>
<p><a href="http://www.thrustssc.com/thrustssc/Engineering/envttest.html">Thrust SSC used</a> two jet engines to provide the power. These operate by sucking air in from the front, compressing it, burning fuel, and forcing it out the back to create thrust. This kind of design needs a large frontal area so the jet engines can scoop up enough air. But analysis showed a design like this would never be able to reach 1,000mph. The frontal area would generate so much resistance that you would never be able to produce enough power with current technology to counter it. Instead we had to design a vehicle with a smaller frontal area and that required the use of a rocket engine (more of that later).</p>
<p>To check the aerodynamics, a computer model was run at the University of Swansea using a system known as <a href="http://aero-comlab.stanford.edu/Papers/SympTransIV_DACAJ.pdf">computational fluid dynamics</a> (CFD). This enabled the team to understand how the car shape would respond to airflow over the bodywork at low speeds (subsonic), as it approached the sound barrier (transonic), and high speeds (supersonic). As a result, we were able to simulate more than 150 designs to ensure that we had a stable vehicle at any speed.</p>
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<figcaption>
<span class="caption">World’s biggest model kit?</span>
<span class="attribution"><span class="source">Stefan Marjoram/Bloodhound</span></span>
</figcaption>
</figure>
<h2>Powering the beast</h2>
<p>Because of the need for a small frontal area, two jet engines would be impossible. The solution was to combine a single jet engine with <a href="http://www.nasa.gov/audience/forstudents/5-8/features/nasa-knows/what-is-a-rocket-58.html">rocket power</a>. Rockets can produce incredible power either by burning a mix of liquid fuel and liquid oxygen or by lighting an explosive mixture of solid fuel and oxidiser. The problem with both these models is the chemicals. Liquid oxygen is very difficult to manage and must be kept at -182°C. Rockets with solid fuel, once started, cannot be stopped until all the fuel is consumed. Once again a third way was needed.</p>
<p>We selected a <a href="https://www.nammo.com/what-we-do/technology/hybrid-propulsion/">hybrid rocket</a> that uses very pure hydrogen peroxide (the stuff you may use to lighten your hair) as an oxidiser and a rubber grain as a fuel. This meant we could turn off the flow of oxidiser and stop the explosion, producing a controllable rocket.</p>
<p>But this created another problem: how to get the oxidiser into the rocket. With a solution suitable for a land-speed record, we used a high-powered Jaguar sports car engine to power a fuel pump that is able to deliver 1000l of peroxide to the rocket in 20 seconds. These three engines together should be enough to get us to 1,000mph.</p>
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<h2>Keeping it together</h2>
<p>Another concern is that all of the components of the car are subjected to huge pressures. For example, the outside of the wheels spin so fast that they generate a force 50,000 times greater than the Earth’s gravity. That means that each gram of material has an effective mass of 50kg. Meanwhile, the shaft that drives the fuel pump must carry considerable torque while moving a liquid that would erode many materials.</p>
<p>To overcome these challenges, the wheels were forged from a single block of high-grade aluminium. This ensured the grains of metal that made up the block were all aligned, reducing the chances of a defect or a rupture. The body shell of the car has been manufactured from carbon fibre to ensure a light but incredibly strong structure. And the fuel pump drive shaft is manufactured from <a href="http://cartech.ides.com/datasheet.aspx?i=103&e=55">Custom 465</a>, a material that is chemically unreactive but strong enough to turn the pump. We then thoroughly tested each component to replicate the forces it will experience during the record attempt.</p>
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<a href="https://images.theconversation.com/files/96022/original/image-20150924-17062-wytaz3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/96022/original/image-20150924-17062-wytaz3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/96022/original/image-20150924-17062-wytaz3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/96022/original/image-20150924-17062-wytaz3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/96022/original/image-20150924-17062-wytaz3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/96022/original/image-20150924-17062-wytaz3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/96022/original/image-20150924-17062-wytaz3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/96022/original/image-20150924-17062-wytaz3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The finished car. No where do we find a parking space?</span>
<span class="attribution"><span class="source">Stefan Marjoram/Bloodhound</span></span>
</figcaption>
</figure>
<p>All of these problems show how designing and building a car like Bloodhound requires a huge wealth of expertise. From the chemists who develop the materials to the engineers who work out how to manufacture the components and integrate them into a single working system, breaking the land-speed record is a cooperative project involving many more people than just the driver. When the car makes its nerve-biting record attempt in 2016, it’ll be as if they’re all in the cockpit with him.</p><img src="https://counter.theconversation.com/content/47976/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Phil Spiers receives funding from Innovate UK
Phil Spiers is a Fellow of the Royal Aeronautical Society</span></em></p>One of the engineers behind Bloodhound, the UK’s anticipated world land speed record attempt, explains how they created a car to reach 1000mph.Phil Spiers, Head of structural testing, Advanced Manufacturing Research Centre, University of SheffieldLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/255102014-05-16T05:16:26Z2014-05-16T05:16:26ZScientists at work: designing the fastest car on the planet<figure><img src="https://images.theconversation.com/files/48167/original/5bgdk4rx-1399633341.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">How fast?</span> <span class="attribution"><span class="source">Bloodhound SSC</span></span></figcaption></figure><p>Apart from a brief break in the 1960s and 1970s, British engineering and drivers have played a <a href="http://en.wikipedia.org/wiki/Land_speed_record#Records">dominant role</a> in setting the land speed record in the fastest cars on the planet. Starting from Lydston Hornsted’s Benz No. 3, which broke the record to reach 124mph exactly 100 years ago, to the current land-speed-record holder Andy Green’s Thrust SSC, which crossed the supersonic barrier to reach 763mph in 1997.</p>
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<p>Now the people behind Thrust SSC have set themselves an even more challenging target to reach the land speed record of 1,000 mph in a new car called Bloodhound SSC. The target date for achieving it is 2016 and it will be attempted in the Hakskeen Pan in South Africa, where they have created a track that is 12 miles long and two miles wide.</p>
<p>The hope in doing this is to inspire a new generation of British engineers and scientists, promote British engineering around the world and spin out technologies that will affect the design of engineering applications and bolster the UK economy.</p>
<h2>How to stay on the ground</h2>
<p>It is now seven years since I first sat down with Ron Ayers and Richard Noble, who led Thrust SSC. In that meeting, we discussed the idea and, specifically, aerodynamic challenges of taking a land-based vehicle to 1,000 mph. It was soon after that bizarre encounter that the picture below turned up on my desk at Swansea University (where I was completing a PhD at the time). </p>
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<a href="https://images.theconversation.com/files/47138/original/drqq6dm7-1398673217.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/47138/original/drqq6dm7-1398673217.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/47138/original/drqq6dm7-1398673217.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=410&fit=crop&dpr=1 600w, https://images.theconversation.com/files/47138/original/drqq6dm7-1398673217.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=410&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/47138/original/drqq6dm7-1398673217.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=410&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/47138/original/drqq6dm7-1398673217.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=515&fit=crop&dpr=1 754w, https://images.theconversation.com/files/47138/original/drqq6dm7-1398673217.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=515&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/47138/original/drqq6dm7-1398673217.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=515&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Early artist’s impression of the yet-to-be-named’ Bloodhound LSR vehicle.</span>
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<p>A key question when starting to design Bloodhound was: how can we keep the car on the ground? This is important because cars at such speeds are at the risk of taking off, much like how airplanes do. For comparison, a typical passenger plane takes off at about 150mph. Of course the thrust offered to planes is meant for it to take off, but for cars going at 1,000mph, any mistake in the aerodynamics would mean disaster. Although this hasn’t happened in recent attempts of speed records, an example from 1967 when Donald Campbell tried to reach a water speed record illustrates what could go wrong.</p>
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<p>Technology developments and the bravery of drivers have kept creating new land speed records all through the last century. Even though the first record was set in an electric powered car, most of the first half of the century worth of records were then dominated by piston engine driven vehicles. These internal combustion engines, as they are known, are found in almost all modern petrol or diesel cars. Using these engines the record could be reached only up to 400 mph. </p>
<p>To push beyond, car builders needed more power. That is when they turned to jet engines and rockets to take over the job of propelling these vehicle. This was also the time when, as speeds kept going up, the resistance caused by air became too important to ignore. Aerodynamics of cars became critical in a successful land speed record attempt.</p>
<h2>Faster, stronger, sleeker</h2>
<p>Aerodynamics is the study of the flow of air moving over bodies and the forces it induces on that body as a result. The mathematical equations that describe this phenomenon are so complex that until supercomputer arrived, a few decades ago, nearly all aerodynamic studies had to be conducted as experiments in wind tunnels or rocket sled tests. </p>
<p>However, now we are able to get remarkably accurate mathematical models by solving these equations using supercomputers. With greater processing power, computers can run “virtual” wind tunnel testing. The flow must be modelling right down the to chaotic turbulence in the flow happening at tiny length and timescales.</p>
<p>But while working on the problem, we realised that keeping the nose of the car down might not be the real problem. In fact, provided that the height of the nose above the ground is just right we have been able to keep the front of the car almost lift neutral by ensuring that the flow rate under and over the nose is balanced. Instead the problem was keeping the rear of the car on the ground due to the strong shock waves generated by the large, outboard rear wheels and suspension.</p>
<p>This unforeseen aerodynamic behaviour led to the 6-month rear suspension optimisation study that resulted in the “delta fairing” design, recently published in the <a href="http://pid.sagepub.com/content/early/2014/03/14/0954407013511071.full.pdf+html">Journal of Autmobile Engineering</a>. This design effectively protects the base and underside of the vehicle from the high-pressure cushion created on the rear wheel when the car overcomes the sound speed barrier. Without the delta fairing design, the Bloodhound would lift off the ground at approximately Mach 0.9 (90% of the speed of sound), much like Campbell’s vehicle did in 1967.</p>
<h2>Feel for numbers</h2>
<p>In those early front room conversations we had not anticipated that getting the twin intake bifurcated (split dual intake) duct in the original design to deliver a suitable flow to the EJ200 jet engine compressor face across the entire speed range would be so difficult. This eventually led us to revert to a single intake above the cockpit canopy.</p>
<p>In those early days we had no real “feel” for how stable the car would be, which in turn meant we didn’t really have an idea of how big the fin would need to be to “keep the pointy end pointing forwards” in the words of Andy Green, our driver.</p>
<p>For the first few iterations of aerodynamic design, where we were almost completely focused on the question of what the external shape of the vehicle should be like and still answering trying to figure out if is 1000mph is even possible, we were constantly being surprised by the aerodynamic performance that the computer simulations were predicting. That was not a little nerve-wracking. I would regularly turn up to engineering design meetings, face the rest of the engineers, and my report would be something along the lines of “this is what the simulations are saying… I have no idea why…give me time”. </p>
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<figcaption>
<span class="caption">A recent Bloodhound CFD flow visualisation showing stream ribbons, and pressure colour contours.</span>
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</figure>
<p>We have been on quite a journey of engineering design. The image below shows the design evolution from 2007 to the current design (config 12). One thing that you should be able to spot from this view of the design evolution is that as we have been homing in on an optimum shape. The extent of the geometric-shape changes have been getting smaller and smaller. Anyone who has used any form of trial and error, which is essentially what we do in engineering design, will be familiar with this. But, more importantly, what else has been happening is that the aerodynamic effects of making changes to the geometric exterior have become increasingly predictable.</p>
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<a href="https://images.theconversation.com/files/47145/original/52qvv6rn-1398673565.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/47145/original/52qvv6rn-1398673565.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/47145/original/52qvv6rn-1398673565.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=510&fit=crop&dpr=1 600w, https://images.theconversation.com/files/47145/original/52qvv6rn-1398673565.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=510&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/47145/original/52qvv6rn-1398673565.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=510&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/47145/original/52qvv6rn-1398673565.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=641&fit=crop&dpr=1 754w, https://images.theconversation.com/files/47145/original/52qvv6rn-1398673565.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=641&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/47145/original/52qvv6rn-1398673565.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=641&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Design evolution of the external shape of BLOODHOUND from config 0 to config 12.</span>
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</figure>
<p>In fact, with the most recent, and subtle, changes to the exterior of the vehicle, Ron and I have been able to confidently predict the impact on aerodynamic performance intuitively and have then used computer simulations check those intuitions. As an aerodynamic designer this is a much happier position to be in.</p>
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<span class="caption">Stream surfaces capturing the complex flow downstream of the Bloodhound as airbrakes deployed.</span>
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<p>But as we get close to vehicle testing that is to happen in 2015, the question is going to be whether this predictability will continue. As an academic researcher, hoping to learn as much as possible about the behaviour of computer simulations in extreme applications, in some senses, I hope the answer to that is negative. It would be more interesting to have a new set of questions to puzzle us. But, for now, we must be patient and get Bloohound built. A new land speed record needs to be made.</p>
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<p class="fine-print"><em><span>Ben Evans works for the Bloodhound SSC project, which is partly funded by the EPSRC.</span></em></p>Apart from a brief break in the 1960s and 1970s, British engineering and drivers have played a dominant role in setting the land speed record in the fastest cars on the planet. Starting from Lydston Hornsted’s…Ben Evans, Lecturer, Swansea UniversityLicensed as Creative Commons – attribution, no derivatives.