Research update

June 2, 2011

Science is ever moving and ever changing, and we’re always finding new things. In this article I’m revisiting some of my past topics with some recent research.



The structure of skin
One of my first articles on thatscienceguy discussed the structure of human skin and how the sun’s radiation affects it. Skin is the largest organ in the human body, and has a critical role in protecting our body from external threats and stopping excessive water loss. The outermost layer, called the stratum corneum, can actually act like a sponge and absorb quite large amounts of water depending on the humidity of the surrounding environment. This ability to absorb water means it needs to be quite flexible, however it needs to balance this flexibility with being robust enough to be able to protect the deeper layers of skin and organs underneath.



Researchers from the Australian National University examined the structure of the stratum corneum to try to understand how its structure allows these dual roles. They found that the keratin filaments which provide skin its structure have a remarkable three-dimensional weave which allows individual fibres to wind and unwind. While the fibres can individually wind and unwind, they do so cooperatively to allow the stratum corneum to breathe without losing structural strength.

The weaving of keratin in its condensed form. From Evans M.E. and Hyde S.T. 2011

The weaving of keratin in its expanded form. From Evans M.E. and Hyde S.T. 2011



Male motor skills
The study which I rated as the strangest of last year investigated the perfect male dance moves to attract women – they even produced videos which demonstrated these moves. Needless to say, it was quite a popular topic!



I explained the importance of that study by likening it to courtship displays by other animals – the males will put on a ‘show’ to demonstrate their prowess to the female, and in the case of humans, dancing may well be one of our courtship displays. But the question remained why exactly do animals (including humans) put on these courtship displays, what exactly are they exhibiting?



Studying the manakin bird, researchers from the University of California Los Angeles found that the female birds preferred to mate with males who performed the courtship display at greater speeds, and were able to tell differences measured in the milliseconds. The speed and energy exertion required by the male to do this courtship display means they have extremely fast heart rates. From this the authors suggested that the courtship display is actually a demonstration of the male’s motor skills, coordination and cardiovascular qualities, and so being able to do it faster shows that the male is stronger and has better quality genes.



And for those wondering what the manakin bird is, from QI:



Sexual attraction
Back at the start of April I blogged about the science of sexual attraction, and in the intervening two months new research has been released which is worth examining.



In the original articles I wrote about the effects testosterone has on males and their attraction to women, and attractiveness to women. Now, new research has shown that men who have higher testosterone are flirtier. Remembering back, testosterone is important for competition between males, so researchers increased men’s testosterone levels by making them compete in computer tasks. The men who showed the highest increases in testosterone as a result of the competition subsequently showed more interest in the woman, made more eye contact with her, smiled more and talked more about themselves. So the testosterone increases induced by competition makes men more attentive to women – maybe this means the best plan before a big date is to do something competitive.



Males have also been found to be able to distinguish whether a female is fertile just from looking at her face. Back in the original articles I wrote how oestrogen levels, which rise during ovulation, slightly change the shape of a woman’s face, making it more rounded and considered as slightly more attractive. Using macaques (a species of monkey), new research has shown that men can recognise these signs of a female’s fertility, but only in faces they are familiar with. Researchers showed male macaques images of females faces which had been classified as being pre-ovulation, during ovulation, or post-ovulation (they found these stages out from measuring the female’s hormones). The male macaques were able to tell the difference between the faces of during ovulation and pre-ovulation, however they could only tell the difference if they were familiar with the particular female. When showed images of an unfamiliar female, they couldn’t tell the difference.



Little is known about the molecular reasons for sexual preference, but research published recently in Nature has investigated how chemicals in the brain may affect who we find attractive. Serotonin, also known as 5-HT, is known to have a huge effect on mood – in fact the most common drug treatment for depression works by making serotonin last longer in the brain. The researchers found that male mice normally prefer female over males as mates. However, when the same breed of mice was modified to make them unable to produce 5-HT, the males lost their sexual preference. When these mice had their 5-HT production restored to normal levels they regained their preference of females over males. This research is the first to show that 5-HT may be involved in sexual preference, and raises the question of whether other brain chemicals are involved in sexual preference.


Lapping dogs
And finally, another update from the strangest research studies from last year, this time the study which examined how cats drank. They found then that cats used the back of their tongues, skim over the surface of the liquid, and then pull rapidly upwards into their mouth. The surface tension would lift the liquid with their tongue straight into their mouth. This seemed much more refined than the simple scooping method that dogs use.



But do dogs really just scoop liquid? It turns out that comment was premature, as new research has now found. Using high speed video it has now been found that dogs too use a very similar method as cats, picking up liquid with the back of their tongue and relying on surface tension and inertia to keep the liquid in place. The liquid travels with the tongue through the oral cavity into the oesophagus, with the tongue then pressing up against the roof of the mouth to prevent the liquid from falling out.



You can see it all in action in these videos:

This is a 300 fps video of a dog lapping. It seems to show spooning of liquid into the mouth but X-ray video tells a different story. From Crompton A.W. and Musinsky C. 2011




This video shows that, contrary to published accounts, dogs do not scoop liquids into their mouths with a spoon-shaped cavity that forms in the ventral surface of a backwardly directed tongue tip. As in cats, an aliquot of liquid adheres to the dorsal surface of the tongue tip and is transported into the oral cavity as the tongue is rapidly withdrawn. From Crompton A.W. and Musinsky C. 2011

SKA: The technical aspect of a mega project

May 17, 2011

SKA is not only about astronomy. The technological advances just to bring SKA to fruition, never mind its operation, will have wide-ranging benefits for everyone.



The SKA project will cost approximately $3 billion to build, and $150 million per year thereafter to run, with a projected lifespan of 50 years. Additionally, around $300 million dollars will be spent developing data networks to link the telescope sites and central processing sites. However, in preparation Australia has spent around $100 million building several pathfinder telescopes. Should the SKA project site be awarded to Australia, these pathfinder telescopes will be joined by the main SKA arrays starting in 2016, with initial data collection beginning in 2019. The building of SKA itself is not expected to be completed until 2024, however data collection and analysis can begin as soon as elements come on-line during the constructino phase. Obviously building a project on this scale will result in considerable employment, materials and transport needs during the construction phase.

CSIRO’s SKA trial ASKAP Antenna, March 2010. Image courtesy of the CSIRO


One of the most mindboggling statistics of the SKA project is just how much data it will produce. Every minute it is in operation enough data will be gathered to fill one million CD’s, which if stacked, would form a pile 1km tall. Another way of considering this data production is that the amount of data passing through the SKA network will be the equivalent of the amount of data flowing around the entire internet. To handle this immense amount of data new data networks will need to be built. A fibre optic network will need to be constructed to link all the SKA locations together for the sole use of the SKA. In fact the National Broadband Network being built in Australia will provide some of the infrastructure required for SKA, however should the NBN not proceed the SKA project will need to build their own network. Advances in the design and construction of these fibre optic networks are one of the potential non-astronomical benefits that SKA will provide as engineers find new ways to overcome any difficulties encountered.



Radio astronomy has helped develop data networks previously. It was through experiences with radio astronomy projects that researchers at the CSIRO were able to develop wi-fi technology which is currently used by nearly every portable device worldwide. SKA will likely produce similar advances in data networks which will feed into common use.



Obviously with this amount of data needing processing, considerable computing power is required. This is another area in which SKA will drive innovation and advancement, as the central supercomputers required to compile and analyse data will need to be able to process around 100 petaflops per second. This processing speed is 50 times faster than the current most powerful supercomputer, and the equivalent of around one billion desktop pc’s. Similarly, the immense amounts of data collected by each telescope will need to be refined before entering the data network. According to Peter Quinn from the Australia and New Zealand SKA project, this will require a supercomputer at each location just to carry out initial refining. As 3000 supercomputers would be prohibitively expensive, newer, faster and cheaper computer processors need be developed, technology will feed down into home computers.

An artist’s impression of the Pawsey High Performance Computing Centre for SKA Science at Perth’s Technology Park. Image courtesy of Woodhead/CSIRO.

Advancements in communications between sites will also need to be developed. Radios and conventional mobile phones would not be able to be used near the SKA sites due to the radio interference they would cause. Similarly, a rail line running near the sites requires new communications networks to allow trains to communicate with controllers. It is unrelated necessities such as these which sometimes throw up the most interesting challenges for engineers. When developing the Very Large Telescope in Chile, floodlights from a (relatively) nearby mine were being picked up by the extremely sensitive optical telescopes. To overcome this, the engineers from the telescope approached the mine and offered to redesign their lighting system. The result was no interference for the telescope, and a more efficient lighting system for the mine who were able to save money from reduced energy costs.



The advancements in technology from SKA won’t be limited to computing and communications however. The power generation needs of a project like SKA will be huge, far more than can be sourced from the current grid. Using conventional power generation will also result in considerable levels of pollution. Therefore, one of the challenges for the SKA project will be to develop green electricity generation facilities. Again, advancements in that field will flow down to common use. Simialrly, development of new processors to fulfil the computing requirements will include making them more energy efficient, technology which could potentially be incorporated into many home and office appliances.



These, and other advancements in technology, materials and engineering will all flow from the SKA project. Even if Australia is not awarded the right to host SKA, it is likely they will still be able to contribute in these other areas, as well as being an integral part by providing the scientific knowledge required for maximising the value of the data output. There is very little risk of the hardware becoming obsolete either, as the entire project is designed to be able to be upgraded throughout its lifespan to become more sensitive, more efficient, and more adept at processing data.



The SKA project is one of the most important scientific undertakings in history, with the potential for the results to be far more significant than those produced by the Large Hadron Collider. This project will expand our knowledge of the universe, our place in it, and how we formed unlike any project before, and do so while developing technology which will greatly benefit our day to day life. It is, quite simply, one of the most important scientific experiments ever attempted, and one which we should all be excited about.

SKA: Something Kinda Awesome

May 16, 2011

Astronomy is one of the oldest sciences, with pre-historic civilisations examining the sky and the motion of stars and planets. Since then the technology has improved constantly, but now an ambitious project will truly push the boundaries of our understanding of the universe by building the world’s largest telescope. This telescope won’t be a single telescope – instead over 3000 individual radio telescopes will together form a telescope on a scale never seen before – the Square Kilometre Array. The SKA project is an international collaboration which is currently made up of 10 members (but is expected to grow), with a select committee from the International Council of the SKA currently deciding where to host it. The two options are southern Africa and Australia and New Zealand, with a decision expected by the end of 2011.



There are 3 types of telescope used in astronomy, optical, radio and infrared, with each type of telescope needs to be located in specific areas which provide the perfect conditions. Optical telescopes, for example, need to be located in a region which has no outside light sources such as the glow from cities. They are also obviously best suited in regions which have clear skies with few clouds to obscure the images. A further complication is that the atmosphere of Earth actually distorts the optical image, so ideally optical telescopes are placed as high in the atmosphere as possible to reduce the amount of distortion, such as on top of mountain ranges. The Hubble Telescope takes this concept to the extreme by being placed outside of the atmosphere, allowing it to take incredibly detailed images.



The main requirement for the location of a radio telescope is for very little background radiation, such as telecommunications or radio and television transmissions. This means they must be placed far from civilisation, and the deserts of southern Africa or Western Australia are ideal for these reasons. During preliminary assessment of the locations for the SKA testing revealed that the background radio transmissions in the WA deserts were extremely low, significantly less than those in Africa in fact. According to Peter Quinn, one of the senior members of the Australian SKA bid, this should put the Australian site at a distinct advantage.



What radio astronomy measures
Stars release radiation over the entire spectrum of wavelengths, meaning they need to be detected by all three types of telescope to form a whole picture of the universe. Radio astronomy measures the high frequency wavelength radiation released by stars.

CSIRO’s SKA trial ASKAP Antenna, March 2010. Image courtesy of Phil Dawson, CSIRO

There are several basic measurements radio telescopes can achieve. If radiowaves being released from a star are being measured constantly, dip sharply, then return to their previous levels, it is highly likely that there is a planet orbiting that star. This dip in radiation is the point when the planet moves in front of the star, temporarily shielding the telescope from the radiowaves emitted from the star. Using this basic principle, astronomers are able to measure the size of planets, the speed they are travelling, and how long it takes for them to complete an orbit of the star.



Galaxies can affect each other similar to tides in the ocean. When they approach each other, move away, or merge, they can change the shape of other galaxies through massive magnetic forces. These changes in shape result in differences in their radiowave emissions, allowing astronomers to understand the structure and shape of galaxies, as well as how they interact, and understand more about these magnetic forces which shape the universe.



Using radiowaves and the Doppler Effect, astronomers can also examine the movement of objects in the universe. The Doppler Effect says that the frequency of waves, whether they are radiowaves, soundwaves, or visible light waves, changes as objects move. As an object approaches, the waves are closer together, however once the object passes the waves become spread out. This is why a siren on emergency vehicles is high pitched as it approaches (short wavelengths), and then the sound changes to a lower pitch as it passes (long wavelengths). The speed at which an object is travelling changes the distance between the waves, with a faster object causing longer wavelengths. Astronomers apply this principle to measure the speed of objects in the universe. If an object is moving away, by measuring the wavelength of the radiowaves coming off it they can calculate the speed of the object. From the speed it is moving, they can then measure the distance from the telescope, allowing precise measurements of the size of solar systems, galaxies, and the universe as a whole.



The SKA will also be able to search for intelligent life throughout the universe. This can be accomplished by detecting and examining the formation of Earth-like planets. Additionally, the sensitivity of the SKA may allow the detection of extremely faint radio transmissions being released by other civilisations. Our Earth gives off radiowaves from human activities, and it may be possible that other intelligent civilisations also release similar radiowaves.

Artist's impression of dishes that will make up the SKA radio telescope. Image courtesy of Swinburne Astronomy Productions and the SKA Program Development Office.

Possibly one of the most interesting applications of radio astronomy is understanding the formation of the universe during the big bang. This concept of essentially looking back in time seems confusing to many people, but is based on quite a simple principle.



Imagine you are looking at a person standing right in front of you. The time it takes for the light (which is what you see) to go from them to you is extremely short. If you then take a step back, it takes slightly longer for light from them to reach you. The further back you stand, again, the longer the light takes to travel from them to you. Now if you were to stand an incredibly long way away, the light would take a long time to reach you, however the image you see would be how they looked when that light left them on its way to you. In the time it has taken to travel that extremely long distance however, the person will have aged, but you will still be seeing them as they were when the light first began its journey. So, you are effectively looking back in time – you are looking at an image when they were younger than they actually are due to the length of time taken for the light to travel across the distance.



The same principle applies in astronomy. An object an extremely long distance away will have released radiowaves an extremely long time ago, but because of the time it takes for those radiowaves to travel across the distance, we are only receiving them now. So what is being detected now was released from a star many millennia ago. If you can detect radiowaves which were released from further away, the older those radiowaves are, and essentially the further back in time you are seeing. It is possible that radiowaves which were released during the big bang, or as astronomers refer to the time just after the big bang, “First light”, are only being received on Earth now from objects extremely far away.



By measuring these extremely old radiowaves we will be able to form a picture of the events which shaped the universe. The further back astronomers can detect will provide more and more information, however they are hopeful that a project on the scale of SKA will be able to detect radiowaves from “First light”, and resolve just what occurred during and just after the big bang to form the universe.



To measure objects further away, the telescope needs to have a larger collection area. However, the distance away you can measure and size of the collection area aren’t a direct relationship; rather they exist as an exponential relationship. This means that to measure something 10 times further away, the collection area of the telescope needs to be 100 times bigger. This is where the SKA comes in to play. With 3000 telescopes each of 15 metres diameter the SKA has a collection area, as the name suggests, of one square kilometre. In short, this is substantially bigger than any telescope project ever built before, and will give astronomers unprecedented sensitivity.

Artist's impression of dishes that will make up the SKA radio telescope. Image courtesy of Swinburne Astronomy Productions and the SKA Program Development Office.

By spacing the telescopes further apart astronomers can also increase the resolution of the images they produce. Having telescopes placed far apart, but still linked, will give incredibly sensitive and high-quality images. The proposal siting SKA in the WA outback will have outstations positioned as far away as New Zealand. The proposal siting SKA in Africa cannot match this spacing, and therefore would not be able to produce images of as high quality.

Potential SKA array station placement in Australia and New Zealand. Image courtesy of the CSIRO

The SKA is one of the most ambitious science projects ever attempted. Next article will talk about some of the technical requirements for such a project, but we’ll leave the final words of this article to Peter Quinn, who when discussing what effect SKA will have on our understanding of the universe said “I think we’ll be surprised and find something we never expected.”



Thanks to my friends at the RiAus and Peter Quinn from the Australia and New Zealand SKA project. More information is at www.ska.gov.au

The 1000mph Challengers

May 4, 2011

Bloodhound isn’t alone in aiming for the 1000mph mark. An Australian effort, headed by perennial land speed record challenger Rosco McGlashan, is also putting together a car which they hope will break the barrier. And in trademark McGlashan style his car sports a very Australian theme, named the Aussie Invader 5R.

Aussie Invader 5R. Image by Mike Annear http://www.mikeannear.com

The design of Aussie Invader 5R
The first noticeable design feature of the 5R is the rounded pencil-like shape, in comparison to the more squared off shape of Bloodhound SSC. Part of this design is due to aerodynamics, the other is due to ingenuity and resourcefulness. In order to keep costs down the body will be made of a 40-foot long high grade steel pipe provided by an oil drilling supplier and steel company. A raised area on the rear third of the car contains the driver’s cockpit, electrical systems and braking parachutes, while a V-shaped underbody has been designed to deflect shockwaves bouncing off the ground, reducing their buffeting effect and increasing the stability of the car.

Aussie Invader 5R from the front. Image by Mike Annear http://www.mikeannear.com

One potential drawback of this narrow pencil-like design in the need to set the front wheels very close together. Such an arrangement, while being good for aerodynamics, may make the car quite unstable and difficult to keep in line. Supersonic cars have a tendency to wander, and such a close set track may make Aussie Invader 5R difficult to control.



The body shape and aerodynamics have been designed using CFD by the Fluid Dynamics Research Group at Curtin University, Perth, Western Australia. Using their know how and expertise built from working with the Jordan Formula 1 team, Aussie Invader’s aerodynamicist Dan McKeon has developed a shape which should be very “slippery” and yet provide good stability.

CFD Pressure chart. Image by the Fluid Dynamics Research Group, Curtin University. http://fdrg.curtin.edu.au/

This CFD simulation shows where pressure builds up on the car’s body, creating drag and instability. One advantage of the close-set front wheels is the reduced area creating drag at the front, indicated by the red area under the nose. The rear wheels also create a large amount of drag, and create an areas where shockwaves will likely form. These high drag and shockwave forming areas could potentially be lessened by creating streamlined cowlings such as those seen on the rear wheels of Bloodhound. The wide-set rear wheels are important for stability, so narrowing the distance probably wouldn’t be an option.



As mentioned, the V-shaped underbody should aid stability by deflecting shockwaves bouncing off the ground. An important part of designing a car such as 5R is understanding how the shockwaves will form and interact with the car. The image below shows that shockwaves are expected to form from the nose and the rear section of the car, with a small shockwave forming from the start of the driver’s canopy.

Shockwave formation at approximately 900mph. Image by the Fluid Dynamics Research Group, Curtin University. http://fdrg.curtin.edu.au

A considerable amount of work has gone into designing the front nose. 7 options were investigated using CFD to create a shape which lessens shockwave formation, does not create lift, nor downforce which would result in drag. Subtle differences in nosecone shape were found to have profound changes to the airflow around the car, and in some cases critical differences which could upset the stability of the car at supersonic speeds. In one instance, a nose shape which drooped twards the ground and was almost flat underneath was found to create downforce, but also created drag (shape 5 below). These characteristics were due to a slowing of the air speed over top of the nose cone which increased the downward pressure on the car. By reducing the amount of droop the airflow over the top of the nosecone was smoothened, preventing this area of slow air and reducing the amount of downforce and the amount of drag (shape 6). Just by extending the length of this nose the airflow was again smoothened, reducing drag by around 30% without any noticeable loss of downforce (shape 7). From optimising the shape of the nosecone not only did the engineers reduce drag and increase the stability at the nose by smoothening the airflow, this smoother airflow also potentially reduced shockwave formation further down the car.

Nose design evolution. Image by Dan McKeon http://www.aussieinvader.com/the_CFD.php

Engines
Apart from the differences in shape and design, there is a very big difference in the way Aussie Invader 5R and Bloodhound SSC will be powered. Rather than going for the combination jet-rocket design of Bloodhound, the 5R will be powered only by a rocket developed by New Zealand based Rocket Lab.

Cutaway image of Aussie Invader 5R's rocket. Image by Mike Annear http://www.mikeannear.com

The design of the 5R’s rocket is based on that of the Atlas rocket used by NASA and is expected to produce around 62,000 lbs of thrust, or the equivalent of 200,000bhp. This makes it around 50% more powerful than Bloodhound’s two engines, which together will produce the equivalent of around 135,000bhp.



The design they have developed uses two liquid fuels rather than the liquid and solid fuel combination used by Bloodhound. A similar design had been considered, but owing to cost and restrictions on the import of hydrogen peroxide the plan was dropped and a new design developed. Instead, a liquid fuel (bio kerosene) and a liquid oxidiser (liquid oxygen) are combined in the combustion chamber and ignited to produce thrust. The complication of this design is that the fuel and oxidiser won’t spontaneously combust in the way the solid fuel and oxidiser used by Bloodhound would. Instead, a third liquid, TEA, is also injected into the engine to ignite and maintain ignition of the engine.



The way the fuel is delivered into the jet engine is a particularly clever piece of design. The team have done away with fuel pumps, and instead the liquid fuels are forced into the engine using pressurised helium. In essence, the pressurised helium is fed into the fuel tanks from one end, pushing the fuel out the other. To start this process, valves at the engine end of the fuel tanks are opened, and the fuel is pushed through and into the engine by the pressurised helium. Because the amount the fuel valves are opened can be controlled, the fuel flow rates can also be controlled, allowing the throttling of the engine and control over the amount of thrust being produced.



This design of the engine for 5R is notable for its few moving parts, which they hope will ultimately be more reliable through its simplicity.

Cutaway image of Aussie Invader 5R. Image by Mike Annear http://www.mikeannear.com

The cutaway picture above shows the packaging of the 5R. From the front, the large tank is the liquid oxygen reservoir, with the pressurised helium tank behind it responsible for forcing the oxidiser into the engine. Behind a bulkhead is the cockpit and safety roll cage for the driver, with the bio-kerosene fuel tank and helium pressure tank behind another bulkhead. The liquid fuel and oxidiser are piped from their tanks into the rocket engine at the rear of the car. Parachutes and electrical systems are contained in the raised section behind the cockpit, above the bio-kerosene tank and rocket engine.



Should all go as planned, the engine should be able to power the car to its maximum velocity in around 20 seconds. Once at 1000mph the driver will then have to throttle back to 75% power, enough to stop acceleration but maintain speed. After leaving the timing area the driver will reduce power in increments until at a safe speed to deploy the air brakes, parachutes and wheel brakes. The reason for reducing power slowly is to avoid the sudden reversing of g-forces which would occur if the power was immediately cut. As discussed in What it takes to go 1000mph Part 2, this sudden reversal of g-force can cause the driver to black out, potentially causing him to lose control of the car.



Rosco McGlashan and his team are currently building the Aussie Invader 5R and hope to be able to have a tilt at the record at about the same time as Bloodhound. With Aussie Invader planning on running at desert locations in the United States or in the north of Western Australia, there may well be a race to reach the mark between the two teams running simultaneously in two locations. While there is no guarantee either team will reach 1000mph, these two engineering adventures will inspire the next generation of engineers, and that should be considered a success in itself.

What it takes to go 1000mph – Part 2

May 3, 2011

Last article examined the major components of the Bloodhound SSC car – the engine and body. However every part of the needs to be optimised to a level of perfection, and this article examines the wheels and braking systems, as well as the effects Bloodhound SSC will have on its driver.



Wheels
They seem like an insignificant part of the car, however the wheels are a critical component. Traditional wheels and rubber tyres just cannot withstand the forces generated by the speeds that land speed record cars travel at, necessitating solid wheels. Thrust SSC used solid aluminium wheels, however the team found that stones were getting embedded in the metal, and the forces was making the metal warp and literally grow around the stones, making them a permanent part of the wheel. Obviously for Bloodhound SSC, something stronger was required.

Cut away image of Bloodhound SSC showing the rear wheels and close-set front wheels. Image from Evo magazine

When Bloodhound SSC runs at 1000mph, the wheels will be spinning around 10,000 times per minute, and undergo forces of around 50,000g. To withstand these forces the wheels are made of solid titanium and weigh around 137kg each. So unique are these wheels and the forces they will undergo, they are being tested at a facility which normally tests power station turbines, and will also have stones fired at them to test how well they resist debris getting embedded.



Braking
Regular car-type brakes are really only effective below around 250mph, so other mechanisms to slow the car are required. Probably as you suspect, the team will use parachutes to slow the car, however, again, these are only safe to use below around 600mph. To bring the car down to a speed appropriate for parachutes, Bloodhound SSC will rely on airbrakes, similar to those found on an aircraft.

Thrust SSC testing its parachute braking system in the 1990's. Image by Bloodhound http://www.bloodhoundssc.com

The problem with aerodynamic drag braking, such as airbrakes and parachutes, is that drag changes depending on speed – the faster an object is going, the higher amount of drag it will have. The flipside of this is that if you’re relying on drag to slow a car, the slower the car is travelling, the less braking force you will have. As a result, Bloodhound will deploy more braking systems as the car slows to maintain a constant level of deceleration.



Driver Andy Green explains the braking procedure:
“1000 mph: close the throttle – deceleration rate is 3’g’ initially, then falls off rapidly
800 mph: start to deploy the airbrake, gradually increasing its area to try and maintain 3’g’ deceleration through the transonic region (800 down to 650 mph)
Below 600 mph: deploy a ‘chute to increase the deceleration rate back up to 3’g’.
Below 400 mph: deploy a second ‘chute if required.
Below 250 mph: apply the wheel brakes as required to stop at the end of the track, ready for the turn round.”



Under normal circumstances the braking procedure will take 4.5 miles to bring the car to a standstill, however in an emergency the car can be stopped in less distance. Should the airbrakes fail the parachutes can still arrest the car in the 4.5 miles by themselves, however should the parachutes fail the car will overrun the test track (extra space is allocated as an emergency run off area).



Cmdr. Green sums up the development of the car, “This is an engineering adventure. We don’t know exactly what’s going to happen. All sorts of things might occur, but they’re unlikely to be catastrophic.”



Effects on the driver
Catastrophic, unlikely, but exciting? Definitely. When the rocket is engaged at around 300mph, Andy Green will experience around 3g of acceleration. This level of acceleration will force his blood into his head, and will fool his body into making physiological changes to try to reduce the blood pressure, such as increasing the size of his blood vessels. While this effect will not have any major effects on Green at the time, when the car starts deceleration he will undergo around 3g of force in the opposite direction – forcing blood into his feet. Because his body has made the physiological changes to reduce blood pressure including the dilation of his blood vessels, this effect will be larger than normal with more blood draining from his brain than he would normally experience under a similar force. So while the actual forces he will undergo wouldn’t normally be enough to cause him to black out, in combination there is the chance his brain will become starved of blood and he will pass out.

During acceleration blood is forced into the head. Image by Bloodhound http://www.bloodhoundssc.com

During deceleration blood is forced towards the feet. Image by Bloodhound http://www.bloodhoundssc.com

The other effect of these forces is that Green is at risk of becoming extremely disorientated. Human balance is controlled by fluid in the ears. Under these acceleration and deceleration forces the fluid in Green’s ears will be forced around, with the effect that under acceleration he may think the nose of the car is lifting, and under deceleration that the nose is digging down. While these forces do actually exist in a normal car, they won’t in Bloodhound SSC. To overcome this disorientation Green will literally have to remind his body that these feeling are an illusion and to try to ignore them.



Adding to this disorientating effect by the acceleration and deceleration forces is the extreme vibration going to be felt by Green. There are two sources of vibration in the Bloodhound car, the engine and the ground. From these two sources, and with effectively no consideration given to driver comfort, the vibrations will be so bad it is likely that Green will not be able to focus and track any of the dashboard displays. While the team has tried to design the cockpit to overcome this effect, it certainly won’t be a smooth, or easy, ride.

Cut away image of Bloodhound SSC highlighting the driver's position. Image from Evo magazine

While Green’s career as a fighter pilot in the RAF and previous drives in Thrust SSC has helped him prepare for the forces he will experience, he has been doing extra training by flying his plane around England… upside down.

Artists impression of the Bloodhound SSC. Image by Curventa and Siemens

On October 4th 1983 after his record breaking Thrust 2 run Noble told the world he had done it “for Britain, and for the hell of it.” With Bloodhound inspiring the next generation of scientists and engineers his intentions are more – ahem – noble, and certainly more ambitious. But it would a brave person to bet against him and his team when they begin their attempts in 2012.



For more information about the Bloodhound project, visit www.bloodhoundssc.com

Some interviews for these articles were carried out by Rob Widdows for Motorsport magazine and Ollie Marriage for Evo magazine.

What it takes to go 1000mph

May 2, 2011

The star components of the Bloodhound SSC car are obviously the engines. Not content with the one jet engine that Richard Noble used on Thrust2, or even the two jet engines used on Thrust SSC, Bloodhound has 3 engines.



Engines
The first engine which will be used by Bloodhound on its runs is a jet engine from a Eurofighter Typhoon, the primary fighter jet of the Royal Air Force. The team have been lent three of these jet engines by the Ministry of Defence, and they are the only engines of this type not in the possession of a national government. As a result the exact specifications of the engine are kept under tight wraps; however we do know that it produces around 13,500lb of thrust, or around 20,000lb with the afterburner lit. In other words it’s an extremely powerful engine, however in the Bloodhound car its role is to power the car from standstill to 300mph. Even powered by a jet engine it won’t be a fast acceleration, with 0-100mph expecting to take around 15 seconds. A fast Ferrari will do the same acceleration in half the time, while the Bugatti Veyron (one of the fastest road cars in the world) takes a little over 5 seconds.


It is what happens after 300mph that sets Bloodhound SSC apart from anything before it. At this point the rocket engine is engaged. Releasing 25,000lb of thrust and running for a 20 second burn, on top of the 20,000lb provided by the jet engine, the car will literally rocket to 1000mph, reaching the mark just 40 seconds after beginning its run. Over this 40 second period the car will have travelled around 6 miles.

Rear view of Bloodhound showing the jet engine and rocket engine outlets. Images by Curventa and Siemens.

The rocket providing this thrust is created by Daniel Jubb who, at just 26 years of age, is one of Europe’s top rocket engineers and sports one of Europe’s most resplendent moustaches. With his company Falcon Projects, Jubb has developed the largest hybrid rocket ever designed in Europe. The engine, measuring 45cm in diameter, contains 1130kg of a synthetic rubber called HTPB as a solid fuel. When fired, liquid hydrogen peroxide is injected into the rocket chamber where it reacts with silver coated nickel discs, producing water, oxygen and immense amounts of heat (around 600°C). This heat causes the solid fuel to spontaneously combust, which provides the actual thrust. This type of rocket is able to be easily shut-down by stopping the flow of hydrogen peroxide into the reaction chamber, allowing an important safety feature.

Daniel Jubb and the 45cm rocket designed for Bloodhound. Image by Bloodhound http://www.bloodhound.ssc

And the third engine? That is a Formula 1 racing engine provided by Cosworth, and provides no thrust for the car at all. Instead, Bloodhound SSC uses this Formula 1 engine as a pump for the liquid fuel powering the rocket engine. During its 20 second burn time the rocket will require 963 litres of hydrogen peroxide fuel, or 48 litres per second. Considering a conventional fire hose will deliver around 6 litres of water per second, the need for a super-powered fuel pump is obvious. In addition to running the fuel pump, the Cosworth F1 engine provides power for the electrical and hydraulic systems.

The Cosworth CA2010 F1 race engine alongside the full size BLOODHOUND SSC Show Car. Photograph by Flow Images

Together, the rocket engine and jet engine will give Bloodhound SSC a total power output equivalent of 135,000bhp (brake horsepower). As a point of comparison, your daily car probably has between 100-250bhp, and a fast road car has around 400-500bhp. A Formula 1 engine, such as the Cosworth running the fuel pump and auxiliary systems in Bloodhound SSC has around 750-800bhp.

Artists impression of Bloodhound SSC with both engines engaged. Image by Curventa and Siemens

But power alone won’t ensure success, and arguably the most important design considerations are given to the body and aerodynamics.


Aerodynamics

The design of Bloodhound SSC has been carried out using computational fluid dynamics, or CFD. Computational fluid dynamics, as the name suggests is a computer based simulation of how fluids (which includes air) flows around objects. By computing how the air flows around the car’s shape engineers can calculate how much drag, lift or downforce the shape is producing. From this, they can also calculate its stability, and beginning to develop the shape until it has the characteristics they seek.


CFD is used by many industries, such as aerospace in the designing of aircraft, and more related, Formula 1 teams use CFD to design their cars. In fact, one team (Marussia Virgin Racing) is using only CFD to design their car, while the other teams use CFD and then re-examine the results using physical wind tunnels. The CFD demands of designing a car such as Bloodhound are so great that the computers responsible for running the programs have more computing power than the English Meteorological Office.

A CFD simulation of Bloodhound SSC. Image from Evo Magazine, copyright of Swansea University, Curventa and Siemens

The aerodynamics of a car such as Bloodhound are absolutely vital. Any moving object transmits sound waves, which travel away from the body. When these waves meet air molecules, it effectively acts as a warning to the air that an object is moving and it needs to start moving out of the way. When the object is moving at the same speed, or faster than these sound waves (i.e. supersonic), the air doesn’t get a warning an object is moving towards it, and the sound waves that normally transmit this warning begin to literally bunch up in front of the moving object. These bunched up waves create shockwaves, which people call the ‘sonic boom’. As these shockwaves form, the air stops moving smoothly over the surface of the car but are constantly changing with every shockwave.


Further complicating supersonic aerodynamics is not the flow of air below the speed of sound and above the speed of sound, but rather the flow of air over objects at the speed of sound. As an object goes through the speed of sound, some air will be flowing just above the speed as sound and some will be flowing just below the speed of sound. This creates conditions in which the airflow is highly unstable, with the number and position of shockwaves constantly changing, meaning everything about the aerodynamics of the car is constantly changing as it passes through this transonic point. A large part of the design of Bloodhound SSC has been centred on how these shockwaves travel over the car, and also interact with the ground surface. Sonic shockwaves have the potential to seriously affect the car, so understanding them and how they form around the car is crucial.


The body of the car needs to be designed to be completely neutral in downforce and lift. A shape which gives downforce will push the wheels into the ground, causing more drag and slowing the car. Conversely, a shape which causes lift will have the obvious effect of the car being extremely unstable and potentially taking off. In fact, one early shape was calculated to result in 12 tons of lift. Considering the car weighs 6.5 tons, this would have a spectacularly undesirable outcome.

Bloodhound SSC after aerodynamic development. Image by Curventa and Siemens

Since the first design sketches were produced in 2008, Bloodhound has been through more than 13 different configurations. One of the most serious problems with some of the initial designs was the layout of the engines, which had the rocket engine placed above the jet engine. When the rocket was triggered, this configuration forced the nose violently downwards. The simple solution was to swap the engines, with the jet engine now above the rocket. However this then meant that the rocket would in fact dig a trench in the ground behind the car, necessitating a slight nose-down angle of the rocket to raise the plume.


Traditionally, land speed record cars have had a large fin to provide directional stability – i.e. to help keep the car running straight. One interesting feature of the Bloodhound SSC car is its surprisingly small vertical fin. The problem is that a fin too large will be overly affected by crosswinds, so a balance needs to be struck. The Bloodhound engineers have developed their car in such a way that the car is stable enough to be able to downsize the fin and reduce the dangerous effects of crosswinds.

Bloodhound SSC from the side, highlighting the small size of the vertical stabiliser. Image by Curventa and Siemens

The engineers have now developed the design to a point where they believe all the characteristics of the car will be ideal. Chief engineer Mark Chapman explains, “What we’ve got is zero lift at Mach 1.3 (990 mph), although there might be some instability on the way to that speed.” The nature of the car and the speeds at which they will be travelling at means that the car will be unstable at some speed, and the challenge was to make it unstable at low speeds but steady at high speeds, when stability is critical. Stability when the car reaches the speed of sound is one of the most vital characteristics of a car such as this, as the car is encountering air traveling at the speed of sound, as well as above and below the speed of sound. As the car is encountering air at different speeds it places different forces on the car, and it is at this transition phase when the car needs to be at its most stable to overcome these buffeting forces.


Next article will continue looking at the technical requirements of a land speed record car and the design features of Bloodhound SSC.