Automatic Parking on Mars

Rover landed
Go Curiosity. Courtesy NASA

 

The Lad watched the NASA website on the morning of Monday, August 6th 2012. There was a live feed from the Flight Control Room in Pasadena as the Mars lander Curiosity was finally deposited on the surface of Mars.

This was no mean feat, for one reason, as the lander was a vehicle as big as a car. For another reason, several other attempts to put vehicles onto Mars have failed. Students should note that, famously, there was a crash landing rather than a controlled descent cost hundreds of millions of dollars. The cause? The calculations supporting the descent were based on a confusion of metric units with imperial units.

Hasn’t every practising engineer suffered something similar? Luckily he or she will not have done it in such a crucial situation or, if so, will have managed to recover the error before disaster was committed to paper or, worse, hardware. Such a risk is exactly the enemy with which the engineer wrestles every day. She or he tries to haul pride out of the successful design of a large or small project. It is a major part of what every engineer does. Then it is not an error in an exam question; it is real.

Curiosity systems
Some of the systems on Curiosity. Courtesy of NASA.

 

One of the most difficult features of the engineering task was communication with the craft as it approached Mars. Quite simply, Odyssey, carrying Curiosity, could hear no radio instruction for 14 mins even at the speed of light and could not return any data, as to what it is doing for example, for the same period. It had to operate automatically, deciding what to do from its own pre-programmed instructions and its own instrumentation resources.

Another remarkable difference between this Martian landing and the Moon landings was the engineering of the descent process. These differences were true engineering and not science. Curiosity was very heavy [nearly 1000kg or one ton] yet needed, with only limited stored energy, to be able to move over the Martian landscape for at least a Martian year. Every part of the vehicle had to be highly efficient in its function with not a gramme to spare.

They set the delivery design criterion to limit the landing shock to be no greater than those which they were expecting as it roved over the boulders and pot holes in the Mars landscape. The vehicle would have, inescapably, to be designed to resist these anyway.

Curiosity was too massive for gas-filled shock absorbing balloons. The design engineers could not justify heavy, mechanical, shock absorbers. They would be used only during the landing and be, ever after, dragged around as so much dead weight. How about retro-rockets firing away merrily right down to the surface under the computer control of a modern radar altimeter? The problem with this is that the violent dust storm kicked up would damage or destroy the vehicle control and scientific systems. Their solution is remarkable.

In the Entry Descent and Landing [EDL] phase, Mars gravity began accelerating the vehicle, Odyssey, towards Mars at many thousands of miles per hour. But then the resistance of the Martian atmosphere was used to slow it down. It converted the vast, kinetic energy of Odyssey into red heat at the face of the conical vehicle. So far so good; we have done it a thousand times before when bringing craft back to Earth. Trouble is that because the Mars atmosphere is much, much thinner than that of the Earth; we can lose only a relatively small amount of the kinetic energy. So, when it gets to be very low and close to the surface it is still going at a hell of a lick. So a giant parachute is then deployed to slow it down some more. That is alright too, for we have done this successfully many times before on Earth. Then though, we were landing in the sea or had heavy shock absorbers.

So what now for the engineers? Now they come to the stickiest bit. Yes, retro-rockets were used to bring the vehicle to zero velocity. The thing is that it was designed so that, when it came to a halt, it was not on the ground. It was several metres above it: here it solemnly hovered too high for the rockets to kick up too much dust. Now break out the Sky Crane. Curiosity left Odyssey and was slowly lowered by nylon rope tethers to the ground.

Sky Crane
Lower away! courtesy of NASA

 

This is how NASA described the process.

In the depicted scene, the spacecraft’s descent stage, while controlling its own rate of descent with four of its eight throttle-controllable rocket engines, has begun lowering Curiosity on a bridle. The rover is connected to the descent stage by three nylon tethers and by an umbilical providing a power and communication connection. The bridle will extend to full length, about 25 feet (7.5 meters), as the descent stage continues descending. Seconds later, when touchdown is detected, the bridle is cut at the rover end, and the descent stage flies off to stay clear of the landing site.

Engineers realise that even the reliable connection and release of nylon rope cannot be a simple task. The risk of a failure needs to be vanishingly small when you are designing a tether mechanism with a billion dollar payload hanging on it. The mechanism MUST work when instructed by a computer after months in space. How would you do it?

Then what happens when the rockets of the Sky Crane are expended? Does it simply fall on top of Curiosity? Noooo! The engineers have designed it to do the ‘Flyaway’ where it scoots off to one side some way away. It is not clear to The Lad however whether, after this, it resembles anything more than a fast-food packet thrown out of a car window.

Congratulations to the engineers of NASA and its contractors for an excellent job. So far! They are hoping that Curiosity will not impose the proverbial fate on the NASA cat for many months to come and so is The Lad.

The Lad has to thank the NASA website for some of the background. Remember, this post contains only the simplest of discussions of only one of the problems faced by the engineers. Without any exaggeration, there will have been thousands and thousands of other problems and optimisation decisions. This Is Engineering.

Engineering is one of the three drivers advancing the human race. This blog describes real professional engineering as it is in the real world. It is not well served by the current media. An engineer is posting: not a ‘scientist’. Its target is the career seeker and also the general public.

The Master ‘Speaks’?

Last night The Lad was delighted to see his Master, Brunel, star in the 2012 Olympic Opening Ceremony.

Danny Boyle, the film director, was the guiding spirit of the ceremony. While some of it was somewhat eccentric, at least, none was PR, journalistic or political boiler plate. There was a true artistic intelligence in charge. At least, that is, till Sebastian Coe and Jacques Rogge shouldered their way in for a drone. Any way, you could see where the £27M went.

One of the set-pieces, seeking to show something of the UK self-image, was a giant coup de theatre representation of the whole Industrial Revolution. It included fiery furnaces, steam engines and full height factory chimneys and a cast of, truly, thousands.

And there, marching through the throng, came Isambard Kingdom Brunel: or, rather, his avatar Kenneth Branagh fresh from his TV detective gig as the gloomy Swede, Kurt Wallander. It also seemed to The Lad to show the thoughtful spirit of Boyle to give a starring part also to the living Sir Tim Berners-Lee, inventor of the World Wide Web.

A couple of puzzles though. First, he was shown to be still wandering the earth at the same time as the Suffragettes. Second, Isambard’s only words were not his own but those of Shakespeare’s The Tempest. Artistic license, The Lad supposes

That led to the question of whether, with his education, would he have been familiar with or capable of quoting Shakespeare? Certainly The Lad thinks that, if any profession is capable of appreciating the great playwright, so too should the engineer. His dealings with forces in the real world will make him appreciate the way that the world is lubricated by great Art.

Naming Convention 03 – A Rebuttal

David Evans did not agree with the points made here and here before. You remember that he is the Membership Director of the British Computer society [BCS] and has commented in the last two posts. This time he responds:

As I inferred previously, it is very important to me that engineers and engineering principles are at home in BCS. They are a critical component (but not the only component) of what this field actually is.

He insists that The Lad is in error.

Computing is sometimes pretty abstract, but not as disconnected from the physical as you suggest. Code is at the end of the day not abstract mathematics, but instructions that will be transduced into physical effects in both light and matter. By definition, code designed to be run will have a physical impact. It can also be argued as the application of computer science, and as such gets back to the core of engineering as the application of science (though predicated of course on computer science being an accepted term). Through those arguments, and potentially others, software engineering is full-blooded engineering, and benefits from the application of the well-developed fundamental principles of engineering common across all fields.

 The Lad notes that his definition of engineering is not the ‘application of science’ but the ‘manipulation of forces’ [for the benefit of human kind]. Thus it is in the earliest days of the Athenian Navy trireme and Roman aqueducts, engineering existed before they had the benefit of science as we currently know it.

I’d also challenge whether the entire body of what you’re currently calling engineers would be comfortable with the suggestion that they are so disconnected from organisations and people. I think both from a design and implementation perspective, people (their behaviours, the impact on them) are often very important to engineers and engineering projects.

This is a valid point that he had not made plain. The truth is that any engineering project has to take proper account of the ‘human environment’. Otherwise it will be deemed, correctly, a failure.

In summary though, The Lad still defines the engineering product as something you can touch. If you cannot then – it is mathematics, or science or logic or philosophy. Or perhaps something else entirely…

… Something else entirely.

David Evans also pointed to a piece by Jeannette M. Wing, President’s Professor of Computer Science, Computer Science Department, Carnegie Mellon University, USA. The Lad will go along with her. As David said “It is essentially an argument for computing as its own discipline rather than a slave to engineering or mathematics.”

A single small quote from Professor Wing’s piece that gives a flavour without The Lad doing her too much injustice is that she says computational thinking has many characteristics, but one is:

[It] Complements and combines mathematical and engineering thinking. Computer science inherently draws on mathematical thinking, given that, like all sciences, its formal foundations rest on mathematics. Computer science inherently draws on engineering thinking, given that we build systems that interact with the real world. The constraints of the underlying computing device force computer scientists to think computationally, not just mathematically. Being free to build virtual worlds enables us to engineer systems beyond the physical world.

Gathering up some loose ends

Or should it be some loose nuts and bolts? The mention of Meccano in the previous post in the picture of Maurice Wilkes and the differential analyser brought The Lad up short for a moment

Meccano and proto-engineers go together in the world view of the generation of The Lad’s father. In this ancient view, it was a pre-requisite that all engineers originally wore the short trousers and built models in Meccano of such unlikely complexity as the Forth Bridge or a Steam Shovel see below and a previous post.

Meccano cover
This work has been released into the public domain by its author, Steve Johnson. This applies worldwide.

 

Gulp! Do such echoes of Wilkes and a previous generation persuade The Lad that the origins of IT involved engineering, albeit of the model genus? Would he have to alter his stance on the variable relationship between IT and engineering?

Scratches head.

Ah, yes. We know what to say… No change in the IT stance – because Wilkes’s machine was analogue. Moving quickly on.

The Name of Engineering on TV

There was a BBC2 “Engineering Giants programme on Sunday 15 July 2012. It was the first of a new series exploring how large machines work. The programme watches, in the words of the Sunday Times, a 14 year-old Boeing 747 jumbo jet being taken apart and re-assembled. In engineering reality, it really means that it was stripped down, examined, repaired as necessary and re-assembled.

It was a pretty good programme considering the dearth until recently of programmes addressing any sort of engineering. Let there be more such.

Pity they called everyone in shot ‘engineers’ when all [except two presenters] were technicians. Yes, all were of the engineering profession. There are many in the profession but not all are engineers. The aircraft designers and those who specify the test standards [none of whom appeared] are the engineers.

Though both are members of the ‘medical profession’ no one refers to nurses as doctors or vice versa. Solicitors and barristers are distinct members of the legal profession.

So to are, in the engineering profession, engineers, technicians and mechanics amongst others. They are not to be confounded.

Oh Lord! I’m tiring! Let us leave that battle to another day.

The Lad suspects that this thread is running out of steam for the moment or, at least, running the risk of trespassing on the goodwill of our reader. She needs a return to a post on ‘engineering-engineering’ and away from ‘name-engineering’. We can come back to it when there is something more to add.

Let The Lad move on for the moment to the next post on the swimmer.

Naming Convention 02 – The Answer?

The Lad held forth in the last post on the use of the name of Engineer in IT. This was based upon a self-awarded mandate. This stemmed from his being a coarse engineer: alumnus of an ancient school who, since time immemorial, have wrestled with forces in the natural world. The conclusion was that there were engineer practitioners in certain IT fields such as chip and disc drive design. He argued that the practitioners in those other IT fields of software design and systems analysis are not engineers.

Some will find this stemming from woeful ignorance or, at least, patronising. Both will tend to ignore any views from here and are fully at liberty to do so. But let us not take this hard line for a moment.

It’s all very well to knock something down; it is at least courteous and professional to make an attempt to replace it.

The name ‘cyber wrangler’ will, quite likely, be dismissed as not serious. The Lad quite likes it as It does seem to have a certain ring to it; besides, he invented it. Trouble is; that ring seems to be like something from the Discworld of Terry Pratchett.

in the view of David Evans Membership Director of the British Computer Society [BCS], It helps when searching for an accepted name, to have a significant back history to survey and learn what one’s profession is about. He seems to be right. He tells a story showing a complete dichotomy of approaches.

In my first IT role during a year out before University, I remember vividly the MD of the company telling me we were Lloyd’s of London people first, IT people second – and he had a background as a claims manager and was a Lloyd’s name. We deliberately dressed, acted, spoke, and to some extent thought like our customers, while the companies such as ICL (who we were competing with very effectively) had people who deliberately identified themselves away from the customer – wearing Mickey Mouse ties and other things like that which almost offended their customers. Our customers treated us as partners and more like fellow human beings than they did other suppliers who they saw more as a necessary evil. Sure, we knew the technology, but what made us special was that we knew the business of our customers. I’d imagine that’s an experience shared by a lot of people in this sector.

David points out that, contrary to the IT workers, all engineers have a centuries-long list of role models. Amongst these Isambard, The Lad’s Master, is relatively recent in that long line. The dichotomy in the story that David told seems to be evidence of an accepted role model.

David goes on to say

[The Lad identifies himself] with an engineer born more than 200 years ago…and it is a positive, emotive identification and one I’d imagine is shared widely amongst engineers who otherwise might have little in common. What identity or figure unites the IT profession? It’s too early to tell.

He mentions as a possible role model Sir Maurice Wilkes. He, on the far right in the picture below, was supervising post-doctoral students as early as 1937. He played a part in much computer development throughout the latter half of the 20th Century; yet who died only in 2010 aged a mighty 97. He certainly influenced many people in IT over many decades.

Maurice Wilkes et al
Maurice Wilkes and his post-docs. By permission of Wikipedia

The machine in the picture was a prototype, Meccano, analogue, Differential Analyser. This was only some 5 yrs before the first electronic machines were conceived and would consign the Analyser to oblivion. Or at least to that vale of mathematical oblivion that consists of a New Zealand Meccano club that has sought to rebuild the machine.

But then he goes on to say things that seem to be significant in terms of whether it is engineering. This is David again:

Some people may identify themselves as engineers to differentiate themselves from others they see as cowboys. Some IT people view themselves as hybrids – do they work in IT or in financial services, for example. … all I know is that people have differing views and seem to hold them for reasons linked to emotion as much if not more than a rationale.

I think for the average IT professional it is so much more about people and organisations. An over-focus on the technology can be a major encumbrance, because most of the issues we see are not to do with the technology. … For many IT people what they are doing is shaping their organisations, and shaping experiences. …

… They enable other professionals to have the right resources at the right point. For example, better use of information is one of the biggest opportunities in clinical practice – from research to safety to decision support. The legal profession will be radically altered by technology, enabling new business models and supply chains (it just hasn’t happened yet).

These aspects seem to be about making organisations work more efficiently through the use of IT. This is not engineering.

The Lad helped to create a small MS Access database application to reflect the existing Garden Design business tasks as it was carried it out. He had also been swept up in the rolling thunder of the introduction of an entirely new organisation in a global company to accept SAP. Two different projects indeed.

Where do we go from here?

The Lad was recently reading a fascinating book called Turing’s Cathedral – The Origins of the Digital Universe by George Dyson. http://www.penguin.co.uk/nf/Book/BookDisplay/0,,9780718194505,00.html?strSrchSql=Turing/Turing’s_Cathedral_George_B._Dyson .

In the very earliest days of the USA side of computer development in 1944, some of the guys working on ENIAC were Eckert, Mauchly and Goldstine who all went on to great things in the industry that later developed. With them [according to Dyson’s book, p74] was “28 yr old Arthur Burks(a logician and philosopher turned electronic engineer for the duration of the war)” That was it! It struck me like a hammer-blow. That was exactly what the software design profession is: the profession is entirely that of practical or Applied Logic.

There it is. A descriptive title dating from the earliest IT days adopted, I believe, by one of the pioneers. The name has a fantastic pedigree where it could be used to describe the greatest ancient philosophers who rank with Newton and Einstein.

Software professionals: not engineers but Logicians. Is there any support for that name?

Let us draw this thing to an end as it is getting to sound too much like politicking. This is just what the tasks of engineering are not about. Good Lord! The Lad is almost regretting seeing the Eric Schmidt, Google speech. Almost.

What’s the Naming Convention 01?

The Lad was delighted to read that the head honcho of Google – no less – was pressing the importance of engineering. This was still true even in the present world, said Eric Schmidt, Chairman of Google, in his speech the other day at the Science Museum, London. To many of his clients that present world is cyberspace. The only way seemingly to get a copy of the speech is to approach Anoek Eckhardt, Communications & Public Affairs Manager, Google UK & Ireland at Email:anoek@google.com

It was very wide-ranging of course but it was in a part towards the end that his very words were:

“Pure Science is a crucial ingredient, but it’s only when theory is applied that you have the recipe for economic success. As Edison put it, the value of an idea lies in using it.

That’s why engineering is so important – it is, by definition, applied science. While astronomy inspires us to reach for the stars, we rely on avionics experts to take us there.. Physics helps explain the behaviour of subatomic particles; nanotechnology uses them to make things. Materials science determines the properties of things we build with; structural engineers apply that knowledge to design things that won’t fall down.

Unfortunately, engineering still has an image problem. It’s high time to move beyond the oily tag stereotype and show engineering in its true modern light.”

What a marvellous statement, as a whole, to emanate from Google. The Lad had a minor quibble about ‘space flight relying on “avionics experts”. Avionics is a shortened form of ‘aviation electronics’. It is an important component of the space project but a wide range of disciplines is needed to get anywhere in Space. But let us move on.

But then The Lad noted also that he referred to

“…the role of engineers in developing ….. video games, texting and social networking,….” as well as “Only 2% of Google engineers …”

This blog is about topics in such as mechanical engineering, civil engineering, electrical engineering, chemical engineering, etc., etc. It has a working definition for such as these which involves natural forces in the world. This blog has addressed this before. Go to ‘The Engineer as Rock God’   http://isambardkingdom.com/?p=4 .

The Lad then asked himself the question whether it is generally accepted, not just in Google, that every professionally qualified IT professional in any speciality [coder, circuit designer etc., etc.] is titled an Engineer? His first thought was that coding is more akin to mathematics or accountancy or the Law rather than engineering.

But then chip design on the other hand seemed clearly an engineering discipline grounded on electrical forces and a type of production engineering. The design of hard disc drives, with their seemingly never-ending increase of storage size, he thinks must involve components of the highest accuracy and of minute size but is engineering nonetheless.

David Evans Director, Membership for British Computer Society, http://www.bcs.org/ , [BCS] which is the Chartered Institute for IT, answered the questions whether the BCS has an official position on the title or whether it could advise on current usage. It transpired that here, with this question, we were stepping lightly into an area freighted with emotion. Highlights of what, in a very full and exclusive discussion, he told us are:

“Interesting question! This is without a shadow of a doubt a very emotive topic for our members, our sector, and for the engineering community as a whole. …

 We offer CEng [Chartered Engineer as offered by many other Engineering Institutions] licensed through the Engineering Council, but as a Chartered body ourselves we offer Chartered IT Professional [CITP]. http://www.bcs.org/content/ConTab/79 … There are … people who are very clearly in the CITP domain and others who are clearly in the CEng domain.

We are very clear that it is necessary for us to have CITP, as there are people who are IT professionals who would have no affinity with or interest in CEng, but are very much the sort of people who should achieve a Chartered status.”

The highlights of what a member also told us are:

“While UK-SPEC lays out the competencies for an engineer, … being an engineer is as much about identity and attitude as it is about competency … to some degree a state of mind. … for the average IT professional it is so much more about people and organisations. … IT professionals enable organisations to function, change, grow and adapt. … engineers will always be part of the profession, and engineering will always be the close cousin.”

Dame Wendy Hall is Professor of Computer Science at the University of Southampton and was Head of the School of Electronics and Computer Science.  http://users.ecs.soton.ac.uk/wh/  She is clearly a power in Global IT and, with her current research interests being the Web, her views carry great weight. She wrote directly to The Lad that:

“I am convinced that software engineering is indeed a branch of engineering. Software engineers build things. The things they build have to be robust, reliable, efficient, effective etc., etc

The robustness and reliability of software is of vital importance in many applications (can mean the difference between life and death) and so software engineering as a discipline must be taught in accordance with the principles of what it means to be a chartered engineer just like any other branch of engineering.

… being CEng means more [than CITP] to me. … we teach a degree called Computer Science but it is to all intents and purposes a Software Engineering degree and I’m very proud that … our students are qualified achieve the award of CEng.

Computer Science is … both a science and engineering. … it has a proper place in the panoply of engineering disciplines.”

Here is an intellectually powerful, highly distinguished academic who is, both a CEng and, also wants to be an engineer. Respect! Genuinely, engineers must be very grateful for this, and accept it graciously. The Lad certainly does. Lord knows; there are so few engineers of the status of Professor Hall apparent to the popular consciousness.

Well there you have it. We have three distinguished practitioners regarding themselves as engineers and two of them have taken significant time to wrestle with our question for us. What are we to make of it? What is there to be said?

Statements and questions follow. Discuss.

Robustness and reliability in the practice and drafting of a law can mean the difference between life and death but is not engineering.

Is not the ‘art of the possible’ in coding governed mostly by the mathematical logic of the mathematician?

Does a hard-nosed, results-oriented attack on obstacles in any endeavour make it engineering?

Can the chip manufacturer or the designer of a high speed printer be a member of the same profession as coder or designer of a server operating system?

Is the cabinet maker a member of the same profession as the toolmaker of her planes and chisels.

No more an author is a printer or bookmaker.

How true is it that “Software engineers build things.”? Should not “things” have more substance than software “objects”?

Has the title ‘School of Electronics and Computer Science’ got it about right?

It has been more difficult to write this post than any other so far. The Lad moved easily into pompous sermonising: there came rolling phrases and solemn cadences about misuse of language, naming conventions, wanting being not enough and so on for several, heavy paragraphs without end coming into sight.

But to hell with it: it’s really simple.

The word ‘engineer’ began with those who began devising and building structures to generate or convert existing forces to replace human, animal or wind and water power with something more convenient. Engines, see?

To repeat: up until recently all those engineers (undoubted engineers – such as civil, electrical, mechanical, hydraulic, etc. etc.) have each waged the one common, fundamental struggle. It is that of dealing with forces already existing in the natural world to bend them to the benefit of humankind. This common feature must, therefore, be the fundamental criterion for inclusion under the aegis of the term.The only exceptions have been those writers who would, describing individuals or tasks, use the term to picture a practical person in some sort of analogy.

Those who design and build physical computers or components are wrestling with electromagnetic forces in electronic components and materials. They are, thus, engineers. However, those who conceive the software structure and write the instructions are not dealing with forces in the natural world. They can only be engineers in some analogy: treating with ‘forces’ of logic in some Platonic world of Ideals.

Then, consider the infinite plasticity of Turing’s Universal machine. What could be more remote from the challenges of the natural world and its real, physical working materials? These challenges and materials comprise the world of the engineer. Ergo! The workers in Information Technology systems design and software programmers are not engineers.

This is not to suggest in any way that the software and systems tasks that they face are easy. Indeed, in some ways, due to the almost infinite size of the field of endeavour; the logical intensity of a complex program and the consequences of error [NatWest, 2012 and spacecraft – say no more] the tasks provide the highest intellectual challenge.

Sorry, not to say bold, to turn Google away,

What to call them is the topic of the next post. Here is a teaser: in what way will this image will be part of it?

Teaser
In the Public Domain (EU and US)

The Go-to People for ship shifting

Spoiler alert! A bilious fragment of truth follows. It is not the whole story but The Lad will defend it from those who will feel that it must be attacked.

The ‘slebs’ of high and low culture are celebrated in the media with acres of print and hours of video coverage. Those who harness the natural world so that it has some surplus, to support the rest of the  human race go relatively unsung.

Driving along the North Wales coast at Easter 2012, The Lad caught a glimpse of a ship, the MV Carrier, grounded in a storm a few days before. The TV news announced that they would seek to re-float it after they had emptied the tanks of fuel oil. It was not a large ship but it was the size of two or three cricket pitches sat against the rocks and weighed perhaps a couple of thousand tonnes. “Shift that ship!” Who do we go to? We go to the men and women who matter. They are the engineers and mariners. They, as far as is possible in this harsh world, are the ones who apply methods beyond the ken of most others to pull irons from the fire.

There are a million possible examples those who have supported the Human Race in its battles with the harshness of the World. Here’s just two at random.

Championed by my guvnor, Isambard Kingdom Brunel, Sir Joseph Bazalgette designed and built the great sewers along the London Thames Embankment. This vanquished both the killer, cholera, which threatened the inhabitants of London and also the stench that violated the Houses of Parliament. It allowed that vast city to continue to thrive and move on to organise mercantile trade and the Empire that brought wealth to England. Building ships on a production line in the Venice Arsenale, a place in itself strangely unreported in English, that on the other hand was well reported, brought wealth to the Medici’s and supported the artists and musicians of the Renaissance.

Without those who make things the artists would be found only in the depths of a cave scratching and smearing colour on the walls. The writers reduced to muttering tales to the tribe by the light of a flickering fire whilst hunching a stinking skin closer round their shoulders. That is before they are dragged out to help the community hunt down or gather some food.

I am briefly embarrassed by being reminded that this piece was written one hundred years to the day that RMS Titanic set sail on its first, and tragically, last voyage. Is this fact a hostage to fortune and the literati? All I can say is that no product of the human mind can be perfect especially when under the control of another human being.

We know that this piece has just been a cameo irritant. Lighten up! It’s scratched that itch for the moment and we need to move on to something more considered.

Here you can see the Dutchmen, Smit. What a marvellous, blunt, simple name for engineers! They are the real marine engineers, naval architects and mariners who do amazing things. No connection , by the way, except of admiration. The Lad has seen, at a distance, some of the things that they can do in moving enormous structures across the sea and then, believe it or not, a mile or more across the land. They have done some work on the notorious ‘Costa Concordia.

So! “Schubert Lab”?

Then why not “Dyson Lab”, or Lovelace, Faraday, Bamford?

The great composers of classical music are celebrated as intellectually subtle, with wide achievements that buttress our civilisation, and enrich our culture.

A series of ‘Schubert Lab’ programmes recently on Radio Three featured experts and were for the interest of the lay–person. They spoke of the keys and chords; not in general but digging deeply into named pieces of music,. The programmes must have totalled something like 3 hours over 8 days in a Schubert strand that was 200 hours overall.

One of them, for example, discussed Schubert harmonies. Laura Tonbridge, an academic, spoke to Tom Service of a song that describes a journey and then he went to the meta-level by suggesting the journey that ends six years later as another song also about a journey. Then Jonathan Cross, a pianist talked about harmonies in another song that “sets up the home key of E minor ….. and then suddenly just by changing one note he moves the bass down a semi-tone and ….the [whole song] as if flips through the other side of a mirror”.

This is no aberration: many programmes scattered throughout the 24 hours on Radio Three operate at this level. It is powerful, technical, professional stuff with no patronising. There is no pandering to an audience that is without knowledge of music theory and notation; it is aimed at those who revel in subtle, new ideas. No dumbing-down here then. And – it’s before the watershed.

The great engineers are equally subtle, with wide achievements that buttress our civilisation, and enrich our culture. Yes. Yes, alright! So too are scientists. If this is a disturbing, unacceptable idea, it is because we hear in our education and the media so little of the detail of the engineers’ work, achievements and satisfactions. There is, in this field, nothing similar to the Schubert Lab other than, possibly, ‘The Material World’ on Radio Four.

Why not have expert, practising engineers speaking of their work, the whys and wherefores?

The Dam designer could describe what the choices are in choosing the type of dam [concrete arch, earth], how to build it without it being washed away as fast as they work, and what she has to consider before the water is finally held back.

A contemporary engineer can describe fibre composite materials and their unusual, non-isotropic properties and what he applies them to.

The discovery or invention of stainless steel has tremendous resonance in the modern world. There are many others to choose from. Some stories could be told by the engineer responsible, others from longer ago could be related by an insightful, modern engineer.

There will be intensely satisfying Eureka moments. It even happens in Mathematics: how many have heard how Poincare had his? He was working on a theory in complex functions and a massive insight came to him just as he stepped up onto the platform of a bus. Its connection to non-Euclidean geometry rose from his subconscious like the filmic Jaws from the sea. It’s the Arrêt De Bus Poincaré now.

Where is the Commissioning Editor – OK. – for Radio Four or BBC Four perhaps?

 

Follow the Money

Once upon a time, long before the title of a Chartered Engineer was even a twinkle in its Daddy’s eye, the MIMechE’s and the AMIMechE’s ruled the mechanical engineering roost, and the Institute of Mechanical Engineers required The Lad to study “The Engineer in Society”. They had in mind to make the tyro engineer look up from his drawing board and slide rule and to recognise that he needed to know that were other aspects to the world.

He had to learn about what motivated a work force. That he had to have scruples and not seek to diddle others. There were some economic aspects to engineering.

Stuff like that.

Nowadays, the Institutions and the Engineering Council rely on the Universities to cover that. Which they duly do, see

http://www3.imperial.ac.uk/mechanicalengineering/study/subjects/year2/me2hmbe

The Lad did not think that they had quite got it nailed then and still does not. The twin of or undercurrent to the profession is wider than that. It is Commerce. It goes as far back as engineering if you consider the Roman Empire with its civil engineering of aqueducts and its commerce across the Empire.

Others have said that an engineer is someone who makes something for a dollar that anyone can make for five dollars. Though over-simple, it emphasises an important point. For the real engineer, economics is intimately bound up with the physical forces with which he or she wrestles. Engineering is ancient but so also is the trading that generates the wealth that funds it.

The Assassination at Bruges

Bruges in the 1120’s was already an amazingly thriving and bustling centre of trade for the whole of Northern Europe. It generated new wealth where it traded in wool, cloth, furs and jewellery. Count Charles the Good was the man who administered the rule of law in all Bruges that so facilitated the storm of trade. You can be sure that, in this financial ferment, engineers would have been busy designing ships, harbours and port machinery to keep the pot boiling.

On Wednesday 2 March, 1127, the Count was assassinated leading to great fears about its effect on trade. We know that the terrible news reached the merchants in London in only 2 days having been carried a distance as the crow flies of 150 miles. This distance, mind, was entirely over the wintry, wild North Sea covered under sail; no mean feat even today. The Lad finds this so remarkable in that it was only 60 years after the Battle of Hastings and King Henry I was on the English throne.

The Seljuk Sultans

While Bruges was in the north east of Europe, in the far south east of Europe where it butted up against Asia, there were the Seljuk Turks. Their enlightened, tolerant government and culture was at its height in the mid-1200s. The Seljuk Empire spanned the ancient trade routes of Anatolia, the famous Silk Road, the camel trails along which the riches of Persia and China were carried to the markets of Europe, and vice-versa.

With trade came wealth, so the Seljuk sultans worked to encourage, increase and protect commerce by road. They improved roads and had their civil engineers and builders build hundreds of beautiful caravanserais to encourage trade with the east.

These huge stone buildings were made to shelter the caravaneers, their camels, horses and donkeys, and their cargoes, to keep them safe from highwaymen and to provide needed travel services.

The typical Seljuk caravanserai is a huge square or rectangular building with high walls of local stone. There are fine images at http://www.turkeytravelplanner.com/architecture/SeljukCaravanserais.html .

Through the main portal, you pass the room of the caravanserai’s manager and enter a large courtyard. Around the sides of the courtyard, built into the walls, are the service rooms: refectory, treasury, Turkish bath, repair shops, etc.

At the far end of the courtyard from the main portal is the grand hall, a huge vaulted hall usually with a nave and three side aisles. The hall is usually lit by slit windows in the stone walls and a cupola above the nave. The hall sheltered goods and caravaneers during bad winter weather.

Caravans were received into the caravanserai each evening, and were welcome to stay free for three days. Food, fodder and lodging were provided free of charge, funded by endowments courtesy of the building’s wealthy Seljuk founder who had also given money for the building’s construction and for its maintenance.

Our Twenty First Century Motorway Service Stations do not benefit from the comparison!

The Merchant of Prato and the Milanese

‘The Merchant of Prato: Francesco Di Marco Datini: Daily Life in a Medieval Italian City by Iris Origo’ is one of the earlier classics of the literature in this field of economic history. It tells how the Merchant began in 1350 his path to a commercial fortune. In 1350 Edward III was on the throne of England and was a power in Western Europe.

 “While kings and princes grappled and made alliances and betrayed and made other alliances, then grappled again, the merchants established their own quietly competent international estate.”

In another book ‘Hawkwood’ by Frances Stonor Saunders there is a pithy, summary of the situation only 10 years later.

Milan was favoured by the merchants who trafficked goods between Lombardy and the great fairs of Champagne and Lyon. It was the merchants who had organised the routes through the Alps, collaborating with local authorities to police the roads, erect bridges and establish posts high in the mountains where their members could find protection from weather and brigands.

http://www.faber.co.uk/work/hawkwood/9780571219094/

All this was referring to Chaucerian times in and around the year 1360.

Note that Stonor goes on, in another accurate summary raising the shades of the contemporary engineers, to write

Milan’s trade was her lifeblood, and her bloody trade was arms, which evolved through access to locally produced iron, large quantities of charcoal from Alpine stands of timber, and the fast-flowing streams to operate tilt hammers and polishing mills.

The relationship of engineering to the Military-Industrial Complex of Eisenhower in the 20 Century foreshadowed here is an important topic that needs to be addressed in another post.

Today

Merchants and commerce are those who engineer the economics of our world into some sort of working order. Then Banking and its offshoots of derivative trading appear and are tending to de-stabilise economic activity.

Despite this, just remember the intimate involvement of engineering and commerce. Argue, if you want, whether commerce is the tool of engineering or engineering is the tool of commerce. Alternatively, symbiosis could be argued. The Lad unsurprisingly holds strongly to the primacy of engineering.

Super Puma Down III

Cracks and Cleanliness

The metallurgist calculated that the markings in the crack had been advancing for between 36 and 100 flying hours before failure. He found this from the marks [behaving almost like tree rings] on the fracture surface. If he could have looked at the fracture on the other piece of the gear [never found], he may have found that more than 100 flying hours could have elapsed.

So, it looks like it was a problem internal to the material of the planet gear that caused it to break up. Rather, that is, than damage introduced externally to the component or outside the mechanism.

What materials does an engineer work with? With what does he design structures? Nowadays, it is most frequently with metals. On some occasions though, he may need to specify a natural material like wood [such as a building structure of internals] or a non-metallic [like fabric for the O2 Arena roof or carbon fibre or plastics for racing car bodies]. For this post however, we will confine ourselves to considering metals.

What is it that is important about metals? Most often it is the raw strength of the material; how great the force is that is required permanently to deform it. Once permanent deformation starts to happen in a component from overload; then we do not know where it will stop. The engineer wants to avoid that. However, there are other strength aspects of metals that may, in certain tasks, trump raw strength such as fatigue strength, creep or toughness. Some metal alloys can be said to specialise in these different capabilities.

A very frequent cause of engineering failures in aircraft is fatigue. That is a failure caused by the repeated application of a stress that is smaller than the ultimate stress that will break a component with a single application. Fatigue is, by definition progressive and usually releases small pieces of metal before final failure. A failure of this type is one of which helicopter designers are extremely wary. It is compressive failure in the bearing race under the balls or rollers, called spalling. It is mainly for such chips that the magnetic chip detectors are seeking.

It helps to understand how to choose a suitable material for a design if we allow ourselves a little over-simplification. For an engineering material, just as for a recipe for something to eat, there are certain defined ingredients and a definition of how they are prepared and treated [cooked?]. For the engineer and metallurgist their chosen material is defined by two aspects. There are the ingredients which are chemical elements [mostly metals but not always]. Then there is the preparation sometimes flattening, [not unlike rolling the pastry for food] or shaping or cutting, and, usually, some form of heating and cooling.

Every material that we use can be had in different grades starting from some form of the raw and passing on up to some form of the extremely pure or refined. From the former to the latter the cost invariably increases. This is not unusual. It is true for a range of fabrics passing from coarse, denim for a pair of jeans to fine silk for a shirt. So it is for metals used in engineering from pig iron to single crystal, nickel alloy for a turbine blade. Such a turbine blade can easily be rated, in terms of the skill with which it is made and its value, as the equivalent of a Fabergé Egg.

Although most workaday components are not made from pig iron; they are at least from mild steel which is. In somewhat simplified terms, iron that had been melted together [alloyed] with around 0.2 % carbon. Most metals however include several components; frequently ten or more. Each has to be carefully controlled; present in the right amount. In the old phrase, to be not too little and not too much. Such alloying components have an important effect on the properties of materials. As we said above, usually it is strength that the engineer looks for but she may be seeking other things such as corrosion resistance or even electrical properties.

These, then, are the materials. What about their preparation?

As we have seen, metal alloys are complex assemblies of crystals. The properties of even a given alloy composition may vary depending on exactly how, on a microscopic scale, the components are arranged. Heating in an oven and cooling carefully is a frequent method for arranging the components of an alloy to provide the grade of strength that the designer decides is necessary.

Another aspect of the preparation is to ensure sufficient cleanliness. The raw materials in the form of ores or scrap often contain traces of other elements or compounds of carbon as impurities. These, after melting, may gather at the crystal boundaries. They may also gather in slightly larger quantities where they force crystals a little apart and are called inclusions. Both will be a weakness or stress concentration. For most components this is only a theoretical weakness. The weakening will either be small or extra material may be designed in.

However, this is cannot be done for some other components that are under greater stresses or where the consequences of failure are too great. For these there is no space for extra material or stress concentrations cannot be allowed to encourage fatigue failure. Aircraft components frequently fall into this category and thus do Main Gear Box planet gears. Because of this, the engineer needs materials that have vanishingly small numbers of inclusions and oxides in the material that she specifies. Clearly, good housekeeping in the production process is essential. But there is one powerful process by which material can be cleaned up. This process is actually two and together they go by the dodgy acronym of VIM/VAR, which stands for Vacuum Induction Melting and Vacuum Arc Re-melting. Good technical data can be found at http://www.cartech.com/productliterature.aspx?id=1246.

Both processes ensure that whilst ever the steel is molten, it is under vacuum to ensure that gases in the atmosphere do not help form brittle compounds that would get mixed in. The feed stock for the VIM part is melted by electrical Induction from coils wrapped around a crucible. It. The end product of this VIM part is a precisely correct alloy composition and also ingots that are of the right size and shape for the next process. The VIM furnace looks like the following.

vim furnace from Timet.com
Vacuum Induction Melting furnace timet.com

 

However, another important feature of high integrity materials is the small size of the crystals. Normal heat treatment can, if it is extended over too long a time, make crystals grow. If we treat the alloy in such a way as to make the crystals small or ‘refined’, the denser network of grain boundaries makes it stronger. The VAR part does just this.

Here the electrodes that come from the VIM process are again melted in the vacuum, but this time by an electric arc. A diagram of such a furnace is shown below. That is, though, not the clever bit. The secret of making small crystals comes from the way that the newly molten pool of alloy is made to re-freeze or solidify. This can be summarised as “very carefully”. The electrode insertion in the crucible; the rate at which it is withdrawn; the electric current supplied; the rate of cooling water flow; and more; will all be controlled simultaneously. This control will ensure, firstly, that the crystals are carefully formed at the right temperature and, secondly with careful cooling, they will then be frozen at a suitable size without being allowed to grow too large.

schematic simple VAR furnace
Vacuum Arc Re-melting furnace

 

The end product is an extremely expensive material that has a micro-structure that is so fine, clean and refined that, compared to a batch of the same alloy before treatment, it is a Premier League football pitch compared to a farm meadow.

The material of the Super Puma planet gear as designed was marketed as a material that could be VAR treated or not. If it had been then there should have been no inclusions or oxides to cause a crack. Is this a case where, despite the best efforts, some unpleasant defect still slipped through? The forensic examination of the gear said that the material composition was correct but does not explicitly say that the treatment had been checked. Could it be that this one component had been made from the correct material but which had not had, as the manufacturer’s specification allows, the VAR treatment? http://www.tatasteeleurope.com/file_source/StaticFiles/Business%20Units/Engineering%20steels/16NCD13.PDF

There might be a case for reviewing the design of the planet gear. It is currently one piece doing two jobs; the inner part is a bearing race and the outer part is the gear. As we saw a crack passed from the bearing part and into the gear part and cracked the component asunder. There could be a case, it seems at first sight, to try and squeeze a separate gear shrunk onto a bearing race into the admittedly small space available. Thus the interface between the two would act as a crack stop avoiding this type of failure.

The time that the crack took to propagate to failure whilst only one chip was detected reminds us that although in-service inspection methods must be robust, they must also be sufficiently sensitive. They must detect the deterioration of a critical component before the ability of the component to carry its design load is compromised. In this sad case, those methods did not. A major plank of a safety case is that any damaged material is released from the outside of the components. In this accident, almost certainly, the fatigue failure began and progressed until the last minutes or seconds entirely within the planet gear. Thus it was contained under its surface and away from the oil flow.

All in-service inspection methods must be such that they can always be relied upon to provide advance notice of problems. The other way lies instant catastrophe.

The engineer designers always have to be eternally vigilant about the giant forces that they harness. Those forces allow us to speed about our business. But if they escape their bounds then they revert, in an instant, to savage cruelty and destruction. So it was at six minutes to one o’clock on April 1st 2009 when the drive exploded and the uncontrolled power flung the men on G-REDL from the heights to the depths in less than a minute.

References

Much of the interpretation and all of the engineering background in these three posts are the responsibility of Isambard’s Lad. Most of the facts and all but three of the images come from the Report on the accident to Aerospatiale (Eurocopter) AS332 L2 Super Puma published by the Air Accident Investigation Branch, Department of Transport, UK. http://www.aaib.gov.uk/sites/aaib/publications/formal_reports/2_2011_g_redl.cfm

Engineers’ responsibility

Engineering is one of the three drivers in the advancement of the human race. This blog aims to give to career seekers and also to the general public a taste of how this might be so. They are not well served by the current media. It is an engineer posting: not a ‘scientist’. It describes real professional engineering as it is in the real world usually in the present and occasionally as it was in the recent past.

For comment on this post use the ‘Leave a comment’ link below. For general comment on the blog, contact us at isambardslad@isambardkingdom.com .

Super Puma Down – II

CSI Metallurgy

 

So! There were chip detectors fitted and working on that day, 1st April 2009, in the gearboxes of the Super Puma G-REDL. How was it then that they had given virtually no warning that the main gearbox was a time bomb that was about to explode at any minute?

Mike M, in the business, told the Lad that a helicopter was mostly a flying collection of gearboxes. The passenger cabin is not much more than an appendage bolted to the engines and the mechanisms.

Gearbox and speeds
This shows the gears to the Main Rotor

 

For most engineering, structural failures, the earliest symptom is a crack. It, mostly, begins to open at the surface of a component. It extends, speedily or slowly, into the interior of the piece, some pieces [chips] breaking away as it does so. Final failure occurs when the crack makes the component unable to carry out its function. has not got enough sound material in its cross-section that is not cracked to cohere under tensile stresses. There is another type of failure that is particularly relevant to a helicopter. Underneath a rapidly rotating ball or roller in a bearing track [race], pieces of the track can begin to crumble away. This does not often proceed to fracture of a race as it is due to compressive stresses. These tend to keep the part pushed together rather than as tensile stresses tend to pull the component apart

The AAIB report tells us, in summary.

One chip had been found on one of the detectors some days before. The mechanics consulted the manual as to what should be done. They thought that it was just a piece of scale. They spoke to the manufacturer’s engineers by phone and email. At each end of this communication channel there misunderstandings as to what had been found, what had been done, had not been done and what should be done. The upshot was, terribly, nothing further was done because no significance was attributed to the ‘piece of scale’ In fact it was bearing steel – of dreadful import. 

In the middle of the last flight, one of the eight planet gears abruptly shattered into massive fragments.

One fragment was over-run by the next planet gear. If it had been the size of a matchstick, a piece of metal would, at the speed of this gearbox, have been crushed, passed through and flung out. There would have been some damage to the gear teeth but no more. This fragment however was of an awful, irresistible size. In the subsequent examination of the wreckage it was never found but everything else was. The size of the gap of its absence tells us in itself a grim story. It would have been a hellish boulder the size of a man’s fist: quite uncrushable. It burst through the strong metal shell of the gearbox outer case, splitting it like an over-ripe tomato with a shattering explosion.

The crew saw the emergency, on-screen warning of the catastrophic fall in oil pressure to almost zero. Two seconds later the craft ceased to respond to any flight controls. The grip of the gearbox on the main rotor was broken. The helicopter rolled and yawed and pitched as though it were a paper windmill in the hand of a child. Twenty seconds later the rotor lifted – free – away from the fuselage; it tilted and then hacked and severed the helicopter tail and its control rotor. The rotor then spiralled away into the air; freed from the burden of the fuselage. What was now left, the cabin and engines together, streamlined like an egg: plunged uncontrollably towards the sea far below, carrying the desolate passengers and crew.

As there had been only one chip found in the oil system, how did the failure start and progress without many more? Call in the metallurgists.

The metallurgists are the brothers in arms of the engineers. Tony T told The Lad that he had the best job in the world, as a failure metallurgist in an engineering organisation with an international reach. He travelled widely to study forensically a variety of failures. Luckily, none of his problems involved loss of life but even if they had, perhaps he would have helped with an understanding as a kind of memorial. If the study of metals appeals to you, go for metallurgy.

Metals are complex structures when you look at them with a microscope. Most people imagine, if asked, that even at that level metal is smooth like a bar of chocolate is smooth. Far from it. Solid metals are crystalline. In a crystal, the overwhelming numbers of atoms are lined up neatly in rows, sheets or repeating patterns. Tiny examples of crystals of this sort are sugar and salt. However a piece of metal is not one single crystal. It is almost always made up of millions of tiny crystals jammed together and each adhering to its neighbours.

Why is this? When the metal is molten, every atom is rushing madly about in all directions. As it cools, pairs of atoms begin to adhere to each other in millions of places, called nuclei. Then other atoms arrive and stick to the first two but only in a neat, repeating array. Imagine 4 footballs: three touching each other to form a triangular pattern and the fourth sitting on top and in the middle of the triangle below.. Such an arrangement could extend as far as you like if you have enough footballs. As the atomic pattern grows, forming a crystal, it continues until it hits another nearby. This is happening in all the nuclei but in a direction depending on the orientation of the first pair of atoms. Each crystal array is at a different angle to that of its neighbour. Thus as the metal cools, each of the millions of atoms in a single crystal is rushing to slip into its place in the pattern. Until, thud, – thud, – thud – and every crystal is jammed up against its neighbours and the whole mass jerks into a solid, rigid mass of thousands and millions of crystals.

In recent, two or three decades some special components such as aero-engine gas turbine blades have each been made of a single crystal. But this can be done only with enormous difficulty, technical cleverness and great expense that are not justified for any other components.

In addition to the conventional processes that are equivalent to standard police work or ‘boots on the ground’ Lots of cutting, polishing and etching with acid to show the structure under the microscope.

Then they zoomed in on the critical areas. The materials engineer has an army or techniques and instruments to study his materials??? Because of the critical importance of the investigation of this accident, she brought to bear some of the Special Forces of the army. There was conventional optical microscopy but also 3D surface optical mapping, 3D X-ray tomography, high resolution Field Emission Scanning Electron Microscopy, and (FESEM) Transmission Electron Microscopy, TEM.

The pictures below show the view, like a geologist overflying a mountain range, of the fracture surface that they had to study to tease out answers.

 

Raw fracture
This is the metallurgist's first sight through a microscope at low magnification
Fracture with areas defined
After a lot of close examination, the metallurgist decides that these areas of the fracture had different causes

 

One of the significant, engineering features of the planet gears is that the bearing track or race and the gear teeth are all in one piece. As we have said before, most of the stresses caused by the bearing rollers are mainly compressive and tending to close any cracks; but here’s the rub, with the integral gear teeth much of the stress field produced is tensile and crack opening. The result with the two fields is that in this double function component, once a crack has crept beyond the race stresses, it enters the gear, tensile stress region opening and, perhaps accelerating. It can eventually pass through the whole gear pinion and break it into pieces.

The morphology [the shape] of the fatigue crack in the second stage planet gear, 13. suggested that it had initiated from a point at or close to the surface of a highly loaded section of the bearing outer race,

The following pictures show a 3D view of their conclusions.

3D image for crack origin
The metallurgist, after much work, was able to calculate the origin of the crack.

 

Ultimately, this suggests to The Lad that the failure and any chips began, if not entirely internally, then at least, within the compressed area of the gear pinion material body. The result? Nothing – no crack – broke the surface to provide chips until the fracture was almost complete and only minutes away from catastrophe.

What can we do about this problem, this type of behaviour? Let’s look at this in the next post.

Engineers’ responsibility

Engineering is one of the three drivers in the advancement of the human race. This blog aims to give to career seekers and also to the general public a taste of how this might be so. They are not well served by the current media. It is an engineer posting: not a ‘scientist’. It describes real professional engineering as it is in the real world usually in the present and occasionally as it was in the recent past.