Category: Engineering and Technology


When we’re little (and in some strange cases, into adult hood), the story of Father Christmas, the fat old man adorned in red and white robes, pervades our lives, (hopefully) making us think about our actions due to the threat of being branded a “naughty child” and getting coal as a present instead of that new PlayStation game you really wanted. However, there comes a time in every child’s life where they learn the truth of Christmas. The truth that an old man doesn’t break into you’re house, leaving gifts, but that instead your parents quietly hide presents in the loft until you’ve gone to sleep on Christmas eve.

And for those of you that still believe, sorry, but the truth hurts.

But, as a bit of an annoying child, one thing always puzzled me, if this legendary man DID exist, how would he get around the world, and all its good children, in only one night? would it even be possible?

Well lets start with the children. There are roughly 2 billion under 15’s on earth at any one time (lets assume this is the point you stop believing in farther Christmas and start buying people gifts instead, you cheapskate). However, since St Nick does’t visit children of Muslim, Hindu, Jewish or Buddhist (except maybe in Japan) religions, this reduces the workload for Christmas night to about 33% of the total, around 660 million children, and with a global average fertillity rate of around 2.5 children per woman (and therefore household) this amounts to about 250 million households, assuming there is at least one good child in each.

Now, farther Christmas has circa 31 hours (if we include things like the rotation of the earth and differing time zones) to make his round trip of the world and its homes, this works out as 2240 visits per second. That is to say, St Nick has around 1/2500 th’s of a second to park up on your roof, break into your house, fill your stockings, place your presents, eat any food left for him, get out again and reach the next house.

Assuming these 250 million homes are evenly distributed around the world (which, of course, they wouldn’t be), we’re now talking 0.23 miles per household, a minimum trip length of 131.1 million miles, without diversions around storms, aeroplanes or mountains.

This means our dear old Father Christmas has to be travelling at a speed of around 1175 miles per second (4,226,000 miles per hour) this is about 5500 times the speed of sound. In comparison, the fastest ever man made object is the Helios space probes, which orbit the sun with an average speed of 44 miles per second, your run of the mill reindeer can run at about 0.00416 miles  per second (15 miles per hour).

The payload of the sleigh adds another interesting element. Assuming that each child gets nothing more than a medium sized LEGO set (two kilograms), the sleigh is carrying over 500 thousand tons, not counting Father Christmas himself. While on land, a conventional reindeer can pull around 150 kilogrmas. Even granted that flying reindeer can pull 100 times this, St Nick would need more than 8 or 9, he would need 33,000 of them. This increases the payload even further, adding another 5000 tonnes to the sleigh. This makes it similar in weight to the Seawise Giant, the longest ship ever built, and by many standards, the largest man made, self-propelling object ever.

500,000 tonnes moving at 1175 miles per second is going to produce a lot of air resistance. It would be equivalent to a spacecraft re-entering the earth’s atmosphere 168 times faster than its supposed to. As a result, the reindeer would almost instantly evaporate into a superheated cloud of atoms and molecules.

Not that it matters much, since St Nick, as a result of accelerating from a dead stop to 1175 miles per second in 0.0004 seconds, would be subjected to acceleration forces of 22 million g’s. A 115 kilogram Father Christmas (which seems ludicrously slim) would be pinned to the back of the sleigh by 217 million newtons of force, instantly crushing his bones and organs and reducing him to a quivering blob of pink goo.

Therefore, if Father Christmas did exist, he doesnt now.

Hope you had a good Christmas, and happy new year!

Alex Davis

References:

http://www.indexmundi.com/world/demographics_profile.html

http://worldchristiandatabase.org/wcd/

http://www.un.org/esa/population/

New Eyes on the Sun: A Guide to Satellite Images and Amateur Observation by John Wilkinson

http://www.tribuneindia.com/1999/99jul11/sunday/head3.htm

A Game of Swords

After reading far too much of the excellent Song of Ice and Fire series, I decided to look a little deeper into the knight’s best friend: A sword! I will not only be looking at the techniques used to create some of history’s most notorious weapons, but I will be exploring the physics behind them, from molecular structures to forces and pressure. This is A Game of Swords!

Anyone who’s anyone (when it comes to weaponry) knows that the most important part of any edged weapon is the quality and design of the blade. There’s no point slashing at your opponents with blunted edges, and you’ll never pierce anything if you have an inferior tip, so how can we go about ensuring that our sword is going to start sharp and stay sharp? The first thing to look at is the material you are using. The most ancient swords, used by the Mayans and Aztecs, were little more than wooden clubs with obsidian chips laid along each edge. Obsidian, made up of Silicon Dioxide with mixed oxides of Magnesium and Iron, is a more a metallic glass than a pure metal. It is this glass like quality that makes it great for sword making, as it is extremely brittle, and will fracture into very sharp pieces. This is all very well, if you happen to live near a long dead volcano, but for the tribes-people of Europe there had to be another way to forge a weapon. The ancient Greeks relied heavily on bronze weaponry, as this alloy of Copper and Tin was strong, sharp and easy to make. Due to the metals used, it was very easy to cast and forge into weaponry. Even late into the iron age, Roman officers carried finely decorated bronze swords into battle. The eponymous Roman sword is the Gladius, which was a very simple double-edged blade with a (relatively long) sharpened point. These swords were primarily designed for underarm stabbing, as in the heat of battle there is very rarely enough space to swing anything larger than a shortsword! The Gladius and its cavalry equivalent, the Spatha, dominated the battlefield for centuries, allowing the Romans the flexibility that they needed, as it only used one hand, the famous rectangular roman (or its rounded sister for mounted combat) shield could be held in the other, offering ample protection for infantry and cavalry alike.

The blades of the common soldiers were actually cast from iron at first, as the early methods of casting it created rather brittle weapons that were prone to breaking. Iron was however much more abundant than copper and tin, and smithies soon started pioneering new techniques to create stronger blades. In East Asia, the metal was often forged from special Tamahagane steel, made from different mixtures of iron sand, which creates an incredibly strong mixture of alloys, perfect for each individual part of the blade. This steel was then folded upon itself repeatedly, creating an edge sharp enough to split a bullet in two (http://www.youtube.com/watch?v=OBFlYwluqMk – skip to about 45-60 seconds to see the slo-mo footage). Steel is so strong because of its crystalline structure, which is created when molten iron is mixed with Oxygen. This is because iron ore contains a lot of carbon atoms. When the iron is cast it will lose some of these carbon atoms, but the more there are, the more brittle the iron becomes. By controlling the amount of oxygen that flows across the steel, the hardness and potential sharpness can be controlled, allowing the smithies to tailor-make their raw forging material. If the steel is more malleable, it can be forged into a stronger weapon, with more interesting curves, but may blunt a lot quicker. In this way a sword can be made from composites of flexible and inflexible steels, with sharp, brittle edges and a flexible body. This is the point at which sword making reaches its zenith.

But now we have our alloys, how do we decide what sort of sword we want? Should our sword be held in one hand, or two? A light sword is good, but would a heavier sword cause a more devastating blow?  The answers to these questions are largely situational, but there may be a physical reason to choose one weapon over another. It all comes down to how much pressure you can apply, and how much pressure your opponent can resist. Pressure is simply the force applied, divided by the area that it is applied to, so greater force equals greater pressure, right? But the force in a sword swing comes mainly from momentum (and therefore the weight) of the sword. So if we want a greater force we’ll need a bigger sword, but a bigger sword means you’ll need to be stronger to actually do anything with it. This is all very well if you’re the knight with the rippling muscles, but what if you’re the poor gangly footsoldier? In that case, would it not be easier to reduce the area that the force is applied to? Especially if your opponent is wearing plate armour and heavy chain-mail, you’ll need something that has a chance of piercing through all those layers (and hopefully your opponent). This is where pointing swords, such as the Rapier come into play. These allow a great deal of pressure to be applied by stabbing forward with the tip of the sword. The smaller and sharper the tip, the greater piercing power your sword has, and the more likely your enemy is to get a bellyful of steel! most of these swords still had two sharpened edges, just in case, but occasionally, a soldier would be so confident of his thrust that his sword would have no edge at all!

Let us suppose we have our stocky knight in his heavy plate armour, with a big, heavy broadsword. On the other side of the field we have the gangly footman, épée in hand, dressed in some cheap chain-mail and an ill-fitting helmet. The knight is a sure bet, right? Wrong! Let us say that the knight’s armour can withstand a direct hit of 2000 pascals of pressure on his breastplate. In anyone’s terms that’s an awful lot of pressure. Now the footman’s épée has a finely crafted tip, 0.5 millimetres across, and his sword weighs about a kilogram. Our footman, quick as an arrow, lunges at our knight with an acceleration of  10 metres per second per second. Newton’s second law states that F=ma, so our footman hits the knight with a force of 10 Newtons. That might not sound like a lot, and in everyday terms it isn’t, but when we feed this value into our pressure equation (bearing in mind the standard length unit is metres), we get a value of 20000 Pascals! Ten times more than the knight’s armour can withstand! Needless to say, the footman would need to give his sword a bit of a clean before he sheaths it again. The outcome might have been different if the knight hadn’t been encumbered with such a heavy broadsword, and indeed, when using a heavy weapon it is always best to be accurate, and better to be well prepared!

Thus we have seen how versatile the humble sword can be, ever the choice of officers and laymen alike, the humble blade served us well for thousands of years. We can see that swords, as well as strategies, can be adapted to suit any situation, and now know that as long as your blacksmith is good enough, you’ll never go unarmed or unprepared!

Harry Saban – The Octave Doctor (Phd Pending)

Sources:

Wikipedia (We’ve all done it, so don’t judge me!) – History of Swordmaking and Steelmaking.

http://www.ehow.co.uk/about_6638014_atomic-structure-steel.html – Atomic Structure of Steel

Armstrong

On the Saturday 25th August, 2012, one of the greatest explorers of modern history tragically passed away. Neil Armstrong.

Known worldwide as the first person to set foot upon an alien world, little general knowledge exists about his early, pre-Apollo life, becoming famous only after his famous moon walk, a fame he hated and publicly shied, becoming a recluse in his later years. However, before all of this he was an accomplished boy scout, a US Navy pilot, a US Air Force test pilot and, for a short period, a university professor.

Before becoming an astronaut, Armstrong was a United States Navy officer and served in the Korean War aboard the USS Essex as an armed recon pilot where, on one sortie, his plane was severely damaged by enemy ground fire, causing him to lose 3ft of his planes right wing. However, against all the odds, Armstrong managed to limp home in his damaged craft and eject into friendly territory.. After the war Armstrong returned to university graduating from Purdue University with a BSc and completed graduate studies at the University of Southern California, gaining his MSci in aerospace engineering. After graduating he served as a test pilot at the National Advisory Committee for Aeronautics High-Speed Flight Station, based at Edwards air force base. Here Armstrong flew several famous craft, including the Bell X-1B and the North American X-15, showing massive potential in both engineering and as a pilot.

Armstrong’s first step towards becoming an astronaut occurred when he was selected for the US air forces Man in Space Soonest programme, a very imaginatively named enterprise to place a man in space before those pesky Russians. In November 1960, Armstrong was chosen as part of the pilot consultant group for the Boeing X-20 Dyna-Soar, a military space plane, and on March 15, 1962, he was named as one of six pilot-engineers who would fly the space plane when it got off the design board.

In the months after the announcement that applications were being sought for a second group of NASA astronauts, Armstrong became more and more excited about the prospects of both the Apollo program, and of investigating a new aeronautical environment. Armstrong’s astronaut application arrived about a week past the June 1, 1962, deadline. Luckily Dick Day, with whom Armstrong had worked closely at Edwards air force base, saw the late arrival of the application and slipped it into the pile before anyone noticed.

On September 13th 1962, Armstrong got the call asking him if he wished to join NASA’s Astronaut corps as part of what was known as the ‘New line’. He jumped at the opportunity, and the rest they say, is history. Neil Armstrong went on to become one of the most famous NASA astronauts in history, becoming the world’s first civilian astronaut, performing the world’s first manned docking of two piloted spacecraft, and of course, being the first man to walk upon the moon.

 

By Alex Davis

Sources:

http://www.nasa.gov/missions/research/neil_armstrong.html

http://en.wikipedia.org/wiki/Neil_Armstrong

http://www.guardian.co.uk/science/2009/jul/09/apollo-astronauts-walking-moon

The fantastic accomplishment of the Curiosity probe landing on mars has once again turned the world’s eyes towards the heavens (if we forget about the Olympics for a moment of course). Using this recent feat of human ingenuity and resourcefulness and a recent trip to the Kennedy space centre for inspiration I’ve decided to write a short piece on the history of human exploration in space, with a post soon to follow about the Curiosity probe, I hope!

Exactly 70 years ago, Wernher von Braun watched on as his brainchild, the V-2 sub-orbital ballistic missile, became the first man-made object in human history to leave the atmosphere and enter, by today’s standards, outer space. In the words of Walter Dornberger, the head of the V-2 rocket programme

“This third day of October, 1942, is the first of a new era in transportation that of space travel…”

Three years later, 1945, at the onset of operation Paperclip and operation Backfire, the American and British scramble for Nazi weaponry and technology, hundreds of V-2 rockets were secretly shipped back to the US, along with some of the Third Reich’s most able minds. For nearly a decade after this, nothing happened, there was little advancement on the German designs and schemes as both western and eastern scientists struggled to come to grips with the sheer complexity and intricacy of the Nazi engineering, but that was soon to change

While the Americans and British were messing with rockets little more advanced than large fireworks, with the fantastic German scientists side-lined for matters of national pride, something interesting had been happening on the far side of the iron curtain…

Using some of this stolen Nazi tech, the Russian space programme, after languishing behind the rest of the world for several years, suddenly kicked into high gear. For years the Soviet cosmodromes had been churning out successful rockets in the forms of the R-1, R-2, R-5 and R-7 families, but here the Russians hit a stumbling block, where do they go from here? The Americans provided them the perfect answer. On 29th July 1955 the U.S. President Dwight D. Eisenhower announced that the United States would launch an artificial satellite during the International Geophysical Year of 1957. Terrified that the Americans would use this satellite as a spy satellite, or worse, the Russians rushed into action, planning, designing and building a fully functioning satellite in just over two years, and on the 4th October 1957 they launched the world’s first satellite into low earth orbit, Sputnik 1. The space race had begun.

Apollo 11 launches from pad 39 A

Skip forward 10 years, to 1967, and Von Braun’s greatest achievement sits atop a launch pad, aimed for the sky, the Saturn V rocket. Even to this day the Saturn V holds several records, for being the tallest, most powerful and the heaviest rocket ever produced. For several years the Americans had trailed behind the Russians in the great space race, relying on reverse engineered technology for their flawed and unreliable Vanguard class rockets, but after the Soviet success of Sputnik the Americans panicked and at the orders of the government, placed Von Braun and his team in direct command of rocket design for the Americans. Almost instantly the American space programme began to pick up speed, and with the declaration in 1961 by John F. Kennedy of the national goal of “landing a man on the Moon and returning him safely to the Earth” there seemed like there could be no stopping the Apollo space programme, the Americans method of placing a man on the moon. Even with its fantastic and, at the time, outlandish goals Apollo succeeded despite the major setback of a 1967 Apollo 1 cabin fire that killed the entire crew during a pre-launch test. Six manned landings on the Moon were achieved. A seventh landing mission, the 1970 Apollo 13 flight, failed in transit to the Moon when an oxygen tank explosion disabled the command spacecraft’s propulsion and life support, forcing the crew to use the Lunar Module as a “lifeboat” for these functions to return to Earth safely. But despite all of this, at Apollo’s discontinuation, NASA declared the programme as “a success”.

This success of landing a man on the moon signalled the end of the space race between the US and Soviet Russia, but it was by no means the end.

The next major breakthrough was Salyut 1, the world’s first space station. Beaten to the moon by the Americans, Russia began to concentrate its resources on sustaining a manned low earth orbit. Although this goal wasn’t achieved truly successfully until Salyut 3 (Salyut 1 was left to fall out of orbit after one crew couldn’t dock successfully and another died on re-entry, Salyut 2’s flight control system failed and an unexplained incident where four solar panels were torn off the craft meant the station was left without power or a way of controlling it, this was again left to re-enter and disintegrate). Salyut 3’s main purpose was as a spy satellite and as a result It tested a wide variety of reconnaissance sensors, returning a canister of film for analysis. On January 24, 1975, after the station had been ordered to deorbit, trials of the on-board 23 mm anti-satellite cannon were conducted with positive results at ranges from 3000 m to 500 m, the departing crew reported that a target satellite had been successfully destroyed.

The latest hurdle crossed in space station building has been with the ISS (international space station), an international collaboration of five space agency’s: the American NASA, the Russian Federal Space Agency, the Japanese JAXA, the European ESA, and the Canadian CSA.

While all of this continues in low earth orbit, countless satellites and probes have been sent deep into the solar system. Some of the most famous ones being the Viking probes of mars, the first man-made objects to successfully land on the red planet and the Voyager probes, currently the furthest man-made objects ever (voyager 1 has recently entered the heliosheath and is predicted to enter interstellar space sometime around 2015). And recently there’s a new one to add to this very exclusive list, the Curiosity Mars probe, the largest and most advanced probe to ever land on another planet. The size of a small car and powered by a nuclear reactor, the Curiosity probe hopes to give us new insights into the history of mars, and whether there has ever been life on the red planet. It plans to do this by incinerating rocks with an on-board laser and analysing the gas given off to detect organic particles and elements and molecules that could support life.

Now we’ve had the most recent, and now we move onto the future. The future of space exploration is a tricky beast to wrestle with, as no one’s quite sure what’s coming. No-one could have predicted the sheer speed at which we progressed from Wernher von Braun’s V-2 rocket, only seventy years ago; after all, we’re now planning manned missions to mars! But there is one group of people who’ve had a go. Project Daedalus was a study conducted between 1973 and 1978 by the British Interplanetary Society, the oldest society of its type, to design a plausible unmanned interstellar spacecraft. Intended mainly as a scientific probe, the design criteria specified that the spacecraft had to use current or near-future technology and had to be able to reach its destination within a human lifetime. The proposed design revolved around a hydrogen-3 pellet driven nuclear-pulse fusion rocket to accelerate to 12 per cent of the speed of light. Aimed at Barnard’s star the probe would carry 18 smaller micro-probes, with an aim to study the atmospheric configuration, the magnetic field strength, and to send back pictures of the star system and its planets, sending this data back to earth via the main probe, which would use its massive 40 metre engine bell as a communications antenna. However, due to its incredible speed, the probe would be unable to stop, hurtling on through space for the rest of its life.

And that’s that, a quick flyby tour of the human exploration of space and where we might be going with it. And to add I would love to have included everything in this article, from Yuri Gagarin and Laika the dog to the British Black Arrow project and America’s plans for a habitable mars base, but, alas, I have a word count to keep to, but if you really want, you could always look them up yourself?

Alex Davis

 

Webography

http://en.wikipedia.org/wiki/Voyager_1

http://en.wikipedia.org/wiki/British_Interplanetary_Society

http://en.wikipedia.org/wiki/Project_Daedalus

http://en.wikipedia.org/wiki/Salyut_program

http://www.bis-space.com/

http://www.nasa.gov/mission_pages/apollo/index.html

http://www.astronautix.com/project/salyut.htm

http://voyager.jpl.nasa.gov/

In this country we have a proud history of aeronautical firsts. We’re responsible for creating the first allied jet aircraft, the Gloster Meteor, the world’s first fully vertical take-off and landing capable aircraft, the Siddeley Hawker Harrier, and even the world’s first jet airliner, the De Havilland comet (which was built in Hatfield don’t you know). But now we have the chance to make another first, to design and build the world’s first, commercially viable space plane.

In terms of the aerospace industry, reaction engines, a small British engineering firm based in oxford, is reasonably new to the scene, but it is already making huge waves in a world dominated by giants such as Boeing, Lockheed Martin and NASA. Their most recent innovation is the SABRE engine; a revolutionary combined cycle, air breathing rocket engine. Simplified, the engine works by burning liquid hydrogen fuel.  At ground level, and in the atmosphere, this fuel is burnt using the oxygen from the air, much like a conventional jet engine accelerating the plane to nearly Mach 5.5, or five and a half times the speed of sound. However, when the craft reaches a higher altitude where the density of the air is not sufficient to continue combustion the air intake of the engine is closed and the engine begins to inject liquid oxygen into the hydrogen mixture, creating, in a sense, a rocket engine, increasing the crafts speed to escape velocity. This radical idea means that it’s just as easy for the craft to travel from London to Sydney, like a typical jet airliner, as it is for it to travel from Cape Kennedy to the International Space Station.

As a practical use for this engine, reaction engines are in the process of designing SKYLON, a reusable, cheap to run space plane. In theory SKYLON should be able to take off from a conventional runway, fly directly into orbit and then return and land on the same runway, much like a conventional aircraft. This creates a huge reduction in operating costs as now special infrastructure or technology is needed to launch the aircraft, no fancy launchers, ramps or launch pads, simply a long stretch of tarmac. This makes it almost 100x cheaper than conventional technology and as a result it can be purchased and used by countries such as Britain that don’t have the money or space to build a dedicated launch site. As a further endorsement for SKYLON the ESA (European space agency) has given the project their stamp of approval, saying “…the SKYLON vehicle can be realised given today’s current technology and successful engine development” and have donated around £1 million to the project fund, enough that they can now begin to build and test various parts of the SABRE engine, such as the engine pre-cooler, which cools the hypersonic air entering the engine down from nearly 1000 degrees centigrade to around -150 degrees centigrade.

This craft is a revival of British ingenuity not seen since the times of the British space project in the late 1960’s and could be a fantastic way of bringing this country to the forefront of world leading technology.  However, not everything is fine and dandy. It is predicted that for the project to be completed funding in the region of £7-12 billion will be needed, and in such a tough economic climate, money like this is hard to come by, and with the last British space programme, the black arrow rocket project, being killed off from a withdrawal of funding, it’s a real possibility that this fantastic idea, may never actually get off the ground.

Sources:

http://en.wikipedia.org/wiki/Skylon_(spacecraft)

http://en.wikipedia.org/wiki/SABRE_(rocket_engine)

http://www.reactionengines.co.uk/

http://www.bbc.co.uk/news/science-environment-17851603

By Alex Davis