Posts in Category: Engineering

Not so High Speed 2

Sunday 3rd February 2013







Posted In: Engineering Tagged: | 2 Comments

Of plans gone awry

Saturday 28th January 2012

About 18 months ago I graduated with a pretty good degree in Civil Engineering, from a pretty good university. In the last few months, I’ve also graduated from an MSc course in one particular part of Civils, again from a pretty good university. During the last year – and particularly the last few months since I finished my masters – I’ve been looking and applying for jobs within that industry. Had a few interviews too, but for whatever reason got nowhere. Lately, I’ve become bored of being skint, so I decided to look for a part-time job, something to do/earn money while I keep applying for “proper” jobs.

And, well, that’s sort of what I’ve done. I’ve taken what is essentially a part-time job, that I know will give me work for the majority of the year. But as part time jobs go, it’s a bit good…

I’m going to be working for a tyre company. Specifically, in the motorsport part of the company. Providing support to their customers in the World Endurance Championship. So basically, I’m going to go to a load of races, getting paid for it, and getting involved in engineering some of the cars that are taking part.

So I’ll be working at races at Sebring (Florida), Spa-Francorchamps (Belgium), Le Mans, Silverstone, Interlagos (Sao Paulo), Bahrain (or wherever they decide to reschedule it), Fuji (Japan) and somewhere in China. And I’ll also hopefully be involved in a bit of testing; I already know that I’ll be going to a tyre test in February, most likely at Monza.

So, my initial plan of “finish uni, get a civil engineering job” has sort of gone awry; I don’t know if this job will lead to any future work (although I get the impression that it possibly could), and of course I’m now not entirely available to start a “normal” office-based engineering job until about November, when the WEC season ends. But, well, I can’t say I’m really complaining…

I still find it slightly amazing that I had a few interviews for jobs that I should really be ideal for given my experience and my qualifications, and got nowhere. But somehow I’ve landed a job that’s completely different to what I’ve done before. Again, I can’t say I’m moaning; at least one of the companies I’ve interviewed for in the last 6 months is now in trouble. And, er, in this job I get to work in motorsport!

And that still hasn’t really sunk in. The way I keep looking at it is: I’ve wanted to go to the Le Mans 24 Hours for years. I’m going this year, and I’ll be in the pitlane for the race. I’ve been to spectate at the Silverstone 6 Hours for the last couple of years, this year I’ll be working there. It’s all a bit unreal really.

So that’s what I’m doing this year. I’m very excited.

Posted In: EngineeringMotorsport Tagged: | 2 Comments

The perils of poor UI

Sunday 15th January 2012

You might remember that a couple of years ago, an Air France plane crashed into the Atlantic. Recently, Popular Mechanics ran an article which explained the causes of the accident using data from the aircraft’s black box. In the immediate aftermath of the accident, it was assumed that something on the aircraft must have failed as it passed through a storm. In fact, that turned out to be wrong; the aircraft was mostly fine, and the pilots “flew a perfectly good plane into the ocean”.

According to the article (which is fascinating, I really urge you to read it), the pitot tubes on the surface of the aircraft (airspeed sensors) became iced over, which meant that the pilots lost the airspeed indicator. Without this data the autopilot couldn’t fully function, and so it partially disengaged. While this went on, one of the pilots decided to put the plane into a climb, which caused it to stall (a sudden reduction in the amount of lift generated by the plane’s aerofoils). When this happened, the pilots tried to continue climbing; the wrong response, and it ultimately caused the plane to lose altitude.

The pilots on commercial aircraft such as this are highly trained, so why, when the plane started to stall, did one of them do precisely the opposite of what he should have done?

‘…the reason may be that they believe it is impossible for them to stall the airplane. It’s not an entirely unreasonable idea: The Airbus is a fly-by-wire plane; the control inputs are not fed directly to the control surfaces, but to a computer, which then in turn commands actuators that move the ailerons, rudder, elevator, and flaps. The vast majority of the time, the computer operates within what’s known as normal law, which means that the computer will not enact any control movements that would cause the plane to leave its flight envelope. “You can’t stall the airplane in normal law,” says Godfrey Camilleri, a flight instructor who teaches Airbus 330 systems to US Airways pilots.

But once the computer lost its airspeed data, it disconnected the autopilot and switched from normal law to “alternate law,” a regime with far fewer restrictions on what a pilot can do. “Once you’re in alternate law, you can stall the airplane,” Camilleri says.

It’s quite possible that Bonin had never flown an airplane in alternate law, or understood its lack of restrictions. According to Camilleri, not one of US Airway’s 17 Airbus 330s has ever been in alternate law. Therefore, Bonin may have assumed that the stall warning was spurious because he didn’t realize that the plane could remove its own restrictions against stalling and, indeed, had done so.’

In normal flight, the computer systems try to make it easier to fly the plane. But once the computers stopped getting inputs from some sensors, those systems disengaged and so altered the behaviour of the aircraft. And so it’s conceivable that efforts to make the plane safer by making piloting the aircraft easier – by simplifying the controls and handing some responsibility to the computers – may have actually contributed to this accident. There could be a number of reasons for that; the change from normal to alternate law may have been unintuitive or non-obvious to the pilots. Or perhaps its simply that taking some of the responsibility for flying the plane away from pilots for the majority of the time causes them to become complacent – to think that the plane couldn’t stall – or meant that they weren’t sure how to react when the computers couldn’t help them. How sensible is it to introduce inconsistent behaviour into any control system, let alone that for a commercial aircraft?

Hang on though, there’s more than one pilot flying the plane. When the aircraft began to stall one of them behaved incorrectly, but this is partly why there’s more than one pilot. Why didn’t the other pilot spot the mistake, and do something to solve it? Well, the Popular Mechanics article also picks up on another part of the plane’s control mechanisms which may have contributed to this:

‘Unlike the control yokes of a Boeing jetliner, the side sticks on an Airbus are “asynchronous”—that is, they move independently. “If the person in the right seat is pulling back on the joystick, the person in the left seat doesn’t feel it,” says Dr. David Esser, a professor of aeronautical science at Embry-Riddle Aeronautical University. “Their stick doesn’t move just because the other one does, unlike the old-fashioned mechanical systems like you find in small planes, where if you turn one, the [other] one turns the same way.” Robert has no idea that, despite their conversation about descending, Bonin has continued to pull back on the side stick.’

The two pilots didn’t know what each of them were doing. So one pilot was pulling back on the controls – the wrong thing to do in a stall – and the other one had no idea.

One one level, I’m simply amazed that this can happen, that the pilots can be unaware of what each other is doing. But then, I also imagine that this is a fairly stressful situation – being thrown around in an aircraft during a storm, with all sorts of alarms sounding – and that within that situation, irrespective of your training, it’s kind of easy to make a mistake.

What I mostly find interesting about this accident is that it was essentially caused by human error, and by the way that humans interact with the aircraft. By that, I mean that the pilots made several mistakes; they shouldn’t have been near the storm in the first place, and they should have acted differently once they reached the storm. But those human errors were, in part, brought about or exacerbated by the aircraft’s control systems.

In other words, this accident was in no small part caused by poor user interface design. The built-in inconsistency between normal and alternate law which possibly confused the pilots at a time when they didn’t have the capacity to deal with the confusion, and the asynchronous controls which hindered communication between the pilots. Because of these things, competent pilots flew a perfectly operable aircraft into the Atlantic Ocean.

These are things that most engineers probably wouldn’t think about. We’re technical people – that’s why we’re engineers – so we think about numbers, about science, about the basic mechanics that underlie how something works. But that’s not the only thing that’s important about a design; it’s also important to consider how people are going to use the thing you’re making. This is applicable to most designs, whether you’re making an aircraft or a building or a phone.

In this case we’ve seen something particularly interesting happen, since the designers have tried to make the plane easier to fly, by delegating some control to autopilots in normal law. But it appears that simplifying the controls might have actually contributed to the accident by confusing one of the pilots. This seems somewhat unintuitive; if we make something easier to use then it seems fair to reason that we also reduce the likelihood of someone using it wrong, and so make it safer. But it’s human nature to be lazy, so when you tell someone that they ordinarily don’t need to think about a particular variable, then they probably won’t think about it at all.

Now I don’t point this out to make an argument against any of the control systems that Airbus build into their aircraft (although, really, asynchronous controls? Isn’t that just obviously a bad idea?), or against making things simpler. Airbus probably know what they’re doing (“probably” being the operative word*). The point is that working out how someone will use something is just as important as figuring out how to make something work; it’s something that should be obvious, but that I suspect is often seen as a secondary consideration.

The designers of the aircraft obviously have thought about this, and their solution was to try to make it simpler to use by hiding some of the complexity from the pilots in normal law; but does that really make it simpler to fly the plane? Perhaps in normal flight, but I suspect that we’d like our aircraft to be designed with abnormal flight in mind as well. And in that situation, perhaps what would really make things simpler is a way of helping the pilots to deal with the complexity, rather than trying to shield them from it and presenting them with unnecessary changeability when that is not possible.

* The Airbus A380 is big, and so Airbus tried to make it as light as possible. To do that, they’ve used carbon fibre reinforced plastic in certain parts of the structure, notably the wings. Carbon fibre: light! strong! stiff! notoriously brittle! Er, hang on a minute…

When I read that they’d used composites, I wondered whether it’d be a great idea. My main concern was durability: would the material start to crack after a certain number of cycles? Imagine my absolute lack of surprise when it was reported recently that Qantas and Singapore Airlines have discovered that there are cracks on the wings of some of their A380s… Airbus say that it’s not important, the cracks are on non-critical parts of the aircraft (although.. really? I highly doubt that it’s designed to crack). I’m sure they’re right, but it’ll be an interesting one to watch.

Posted In: Engineering Tagged: | 5 Comments

Another hybrid?

Sunday 4th December 2011

At first glance, electric cars seem to be a good idea. Certainly at current prices, using electricity seems to be a relatively cheap way of fuelling a car. And for many people, who mostly use their car to make short journeys, the range issue isn’t generally a problem.

However, most people also use their car for occasional long trips. For example to visit friends or relatives who don’t live locally. And so although people generally only make short trips, they still need it to be able to make longer journeys on occasion. I think this is probably one of the major barriers preventing wider uptake of electric cars at the moment (price being another big one; a comparable EV typically costs 50-100% more than the alternative conventionally-powered car). Even if you only make short trips 95% of the time, most people don’t want to buy or rent another car for the other 5% of the time.

But perhaps there’s a way to have the best of both worlds. At the moment, certain cars have a “hybrid” system. Here, a traditional internal combustion engine (ICE) provides power in the first instance, and this is supplemented by an electrical system which collects energy which would otherwise be wasted (in braking etc). Seems like a good idea, although I do find it surprising that many of the cars which use this system don’t actually seem to do it very well. For example in the real world, a Prius only seems to be about as efficient as other mid-size cars (e.g. the Ford Mondeo or the BMW 3-series) which use reasonably-sized diesel engines, and are much less efficient than many smaller cars which use small engines with forced-induction. Only the Prius is more harmful to the environment, once you take into account the materials used to manufacture the hybrid system…

I reckon that this might be the wrong way to go about making a hybrid drivetrain. Rather than having a drivetrain that is mostly ICE and partly electric, why not have the balance the other way?

By that I mean, rather than fit an ICE drivetrain with a slimmed-down electric drivetrain, why not fit a small engine to an electric drivetrain? So for short journeys you can run solely from the batteries, which you can then charge as you need. But then if you want to make a longer journey – or if you run out of electricity – you can fill up with petrol or diesel and start the engine.

I can’t see too many downsides to this. It’d be harder to package and would increase the weight slightly, but I guess that this is only the same problem as is faced with the drivetrain on other types of hybrid. But in this solution, the car gets the best of both worlds.

Of course, I’m not a mechanical engineer so there could be problems I haven’t foreseen; perhaps there’s a good reason why no-one uses this drivetrain (if that’s correct. Maybe some cars do, and I just haven’t heard of them). But I really can’t think of many negatives which would outweigh the obvious benefits: EV efficiency for smaller journeys, and ICE range for longer ones.

All this being said, has anyone actually worked out whether EVs really are more efficient than cars with an ICE? Or does using an electric drivetrain simply move the location at which fuel is consumed away from the vehicle? I actually don’t know the answer to this, although if making a journey using an electric car costs less per mile, I guess that’s a good hint.

Posted In: CarsEngineering Tagged: | 3 Comments

Thinking about climate change

Wednesday 23rd November 2011

Climate change is a significant topic that affects the lives of pretty much every living human. As such, discussions about the subject can often get quite heated, with two distinct camps. One side says that climate change is caused by carbon dioxide emissions, and that the consequences for humanity will be absolutely dire. The other side seems to claim that the climate isn’t changing, or that the other side are making things up. To stoke up their claims both sides resort to bad science, misrepresentation of good science, and lots of good old ad hominem attacks. Here are a few things which we know to be true, at least as far as we can be sure about these things:

  1. Climate is changing. It always has, it always will.
  2. Global temperatures have risen.
  3. CO2 levels in the atmosphere have risen in the last circa 200 years, driven by industrialisation.
  4. CO2 is a greenhouse gas. Its presence in the atmosphere does have a warming effect (we’re dependant upon this for our survival!)

Sensible discussion of the topic has to start from at least these facts, as they represent the state of our current knowledge. It is ridiculous to claim that any of these 4 are untrue, because as far as we know all the evidence suggests that they’re not. But equally, sensible discussion of this topic cannot simply stop here. Because these facts raise some questions which need to be answered before we can devise any meaningful response to this issue:

  1. To what extent does CO2 cause changes in temperature? If there is x amount of CO2 added to the atmosphere, what is the corresponding change in temperature?
  2. To what extent is this a problem? What is the cost of doing nothing to stop climate change?
  3. If we can find ways to reduce/stop CO2 emission, what are the costs of doing so?

To think about those three questions, I’ll break them down into the appropriate subject areas. Question 1 is about the science, about working out what’s happening with the climate. Question 2 is about how we can deal with the effects of climate change and the cost of doing so, and so is really about engineering. And the heart of the third question is about reducing the reliance on energy sources which cause CO2 to be emitted (as energy use is the principal cause of CO2 emissions).


When we’re talking about climate, we’re talking about a huge, chaotic system. To start to understand how it works, we’re talking about modelling the flow of fluids (namely water and air) across the entirety of the Earth’s surface, taking into account countless different variables and the way they interact with each other. This is really hard to do, at least with any accuracy. And it’s really hard to look at such a system and to derive the effect that one particular variable has (namely CO2 concentration). So to come back to the first question I posed. Do we know the extent to which CO2 causes warming? No, we don’t. We can run all kinds of models to find some sort of estimate, yes, but finding out whether that model is accurate is not a trivial problem.

There’s lots of confusion about this, it seems. One side of the climate debate tries to make out that climate change is caused by anything but the activities of mankind, whilst the other is pretty set on the idea that it’s all down to CO2. Both sides vilify the other, and that doesn’t really make any sense. We can’t yet say – with any certainty – what effect the CO2 generated by our activities is having on the environment; but CO2 is a greenhouse gas, so it really isn’t a leap to say it’s having some effect.

A good example of this problem can be found when we examine the temperature change over the last decade, and compare it with the change in CO2 concentration in the atmosphere:

Temperature data are global averages from the HadCRUT3 dataset of temperature records. CO2 concentrations recorded at Mauna Loa Observatory, Hawaii.

The basic theory is that CO2 is causing mean temperatures to increase, and yet looking at the above graph, it’s rather hard to find such a relationship. HadCRUT and BEST both show that there has been no warming in the last decade (in fact, the HadCRUT data used here show that mean temperatures have decreased very slightly), even though CO2 concentration has steadily increased. More than likely, we can’t draw too many conclusions from this; 10 years is quite a small period of time when discussing climatic events which take place over a significantly longer amount of time. But at the very least, it causes us to question the claims about the significance of CO2. Because if CO2 really is as dangerous as we’re told, has such a dominant effect that we need to make drastic steps to reduce the amount we emit, we really should have seen accelerated warming in this period.

Now, for the sake of clarity, I am most definitely not saying that CO2 does not cause warming at all; simply that we haven’t properly quantified the warming effect that’s caused by our CO2 emissions. And that, whilst the temperature rose during the 20th century, we probably don’t know the whole story of why that happened; most likely it’s been caused by a number of things, and human activity could be a large or a small component (for instance, we know that solar activity has increased during the last few decades). Climate is variable, it always has been and it always will be, and so there isn’t a steady baseline to make comparisons from. We can’t say that CO2 and temperature have both risen, therefore increased CO2 has caused the temperature rise; it simply isn’t that straightforward. And it’s rather foolish to dedicate lots of resources to the cessation of CO2 emission, when we don’t know whether that really is causing unnatural climate change.


So. For the sake of argument, let’s ignore everything I’ve just said. Let’s make the assumption that CO2 is driving climate change, and that if we continue to pump it into the atmosphere it’ll cause a global temperature rise that will cause the environment to change. How could we deal with that?

Fundamentally, this is a problem about the maintenance of the natural and built environment. That’s not a new issue, we’ve been doing this for millennia, and engineers have been doing it using a scientifically rigorous approach for centuries. It’s what Civil Engineering is all about, and we’ve gotten pretty good at it by now. So, let’s look at one particular issue that is likely to be a problem, should global temperatures continue to rise: higher sea levels.

The first step in solving an engineering problem is to work out what exactly the problem is, so we’ve got to find out how much the sea is likely to rise. At the moment, the consensus seems to be that the sea level will rise between 75cm and 2m in the next 100 years. It’s quite hard to visualise what that looks like, what that really means for us. Happily it’s quite easy to model this, to see which bits of land will be flooded after a given change in sea level:

Map of British Isles with 2m rise in sea levels. Areas of land which are below the increased sea level are shaded blue. Source:

Not a particularly significant change, actually. The worst-affected area is landlocked anyway, so I guess it might not be encroached by the sea, although flooding may become more likely. But if we really wanted to, these are problems which we can easily solve. If a place is under threat from a 2m sea level rise, then we can build a dyke (or similar) to stop it from being flooded. If flood risk in a region is increased, then there are lots of techniques we can use to deal with that too. Or, in some cases it might be best to simply move away from the areas which are likely to flood, as there’s still plenty of higher land left. None of these approaches should really be that costly, certainly in comparison to some of the alternatives.

These problems can be solved, and in many cases are already being solved. It’s also worth mentioning that on the global scale, climate change might actually cause positive effects in some locations, for example by moderating the climate of places which are currently very cold. And so when we examine these issues to try to think about how to deal with the possible effects of climate change, it quickly becomes apparent that this is something that we know how to do, and that climate change really isn’t the end of the world.


Now let’s go even further with our assumptions by saying that we’ve decided that we should try to reduce the amount of CO2 we emit. The largest cause of anthropogenic CO2 emission is the burning of fossil fuels for energy. Therefore to make a meaningful reduction in emissions, we must use alternative sources of energy as much as possible.

Several countries have agreed to targets to reduce their CO2 emissions, and there are several policies which are in place to try to achieve this. Firstly, there are high taxes on CO2 emission, in order to discourage activities which cause pollution. There are also subsidies available for the production of certain (supposedly) sustainable sources of energy – wind power, solar power, etc. – to encourage people to install these facilities. And to try to make current fuels “greener”, a certain amount of bio-ethanol is blended with petrol and diesel used for transport.

There are problems with this: it’s expensive, and often grossly unfair. Taxes on energy affect everyone; directly in the price we pay for transportation, heating and electricity, and indirectly in the price we pay for goods. You might argue that, well, we’re wealthy, and we can afford it. And we probably can. If we think it’s an acceptable trade-off, then we can probably afford to sacrifice some luxuries, or lose a certain amount of investment – and jobs – even with the current state of the economy. It makes life difficult for ourselves, but not impossible.

Subsidies are less excusable. It’s the classic argument that subsidies distort the market and make it less efficient. Which is a good argument; we want to use alternative sources of energy when it’s actually efficient to do so, not just because we think we should, as that simply makes energy more expensive than it needs to be. This is also deeply unfair, as it benefits those who can afford to invest in “green” energy, at the expense of those who cannot. Frankly, I think it’s inexcusable to drive up energy prices for the majority with a scheme to provide cheap energy to the minority who are wealthy enough to buy into the scheme.

On the subject of unfairness, there’s also a broader point to be made. Firstly, we’re telling poorer parts of the world that they need to not emit CO2, but often the only affordable sources of energy available in such parts of the world are those which cause lots of CO2 to be emitted. So in a way, we’re asking less developed parts of the world to stay undeveloped, to stay poor. Which limits access to things like healthcare and education in those parts of the world, and so undoubtedly causes a huge amount of damage (or rather, it would if they all listened to us).

On top of this, we impose “green” policies which directly cause actual damage. For example, the requirement that fuels be blended with bio-ethanol has had the effect of raising the price of some foods. This increased price has meant that some people simply haven’t been able to afford to eat, which is thought to have caused at least 192,000 extra deaths last year. Some of the poorest people in the world are being starved because we want to burn their food to reduce our CO2 emissions. Whatever your views on climate change, that should make you mad.

What should we do?

The point that I’m trying to make is that our approach to climate change needs to be more intelligent. The science is very complicated, and probably not well-understood enough to be the basis of policy decisions which can have profound effects. We cannot say with confidence that we are the cause of the changes in climate that we observe.

Given this, it seems sensible to have a different approach to dealing with climate change: to analyse the costs and the benefits of the situation, to work out what really is the best course of action.

The cost of doing something about the possible threat of anthropogenic climate change is massive, as it calls for a fundamental change in the way we do things. It calls for us to abandon the sources of energy which allow us to access many of the resources we need to maintain our standard of living, and it calls for us to deny poorer parts of the world the opportunity to grow and develop and improve their basic standard of living. That is a massive cost. Given that the modest things we’ve already done have resulted in hundreds of thousands of deaths, it’s scary to consider the possible cost of doing more.

Additionally, the potential benefits of reducing CO2 to combat climate change are comparatively small. All we’d do is avoid a certain amount of engineering work which would be required to adapt to the changing environment. It’s not clear that we’d save all that much; the built environment will need to be maintained in the coming years regardless of climate change, and so all we’d do is change the parameters of problems that need to be solved anyway. But solving those problems becomes infinitely easier if we maintain our access to cheap, abundant energy.

Fundamentally, it seems to me that our response to the possible threat of anthropogenic climate change is wholly disproportionate. We’re causing more harm than we could ever hope to stop; we’re spending lots of money (and causing lots of deaths) for solutions that might not work, for a problem that probably isn’t that severe. Whatever way you slice it, that isn’t an intelligent trade-off.

Posted In: EngineeringPolitics Tagged: | 2 Comments

This is worth a listen

Monday 4th April 2011



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Friday 18th March 2011






Sigh sigh sigh.


Sigh ad infinitum…

Posted In: EngineeringPolitics Tagged: | 1 Comment


Sunday 6th February 2011

In the last week, the 2011 F1 season got under way, with the start of pre-season testing. The best bit of this is that we get to see all the new cars, and so get to have a look at what clever new bits and pieces they’ve got.

The new McLaren was unveiled on Friday, and it’s pretty interesting. I wrote last year about my admiration for their design, and this year I had pretty much the same reaction.

Some background: F1 cars have various aerodynamic appendages which work to push them to the ground, which gives them such immense grip. One of these parts is the rear diffuser, which sits at the bottom of the car at the rear, and increases the velocity of air moving under the car so as to reduce the pressure and create downforce (they used to run full-length venturi tunnels under the car, and one team even went so far as to use a fan to suck air from under the car). In the last two years, the teams have used a loophole in the regulations to make their diffusers bigger, to give the car more downforce and so more grip. This loophole has now been closed, so more grip needs to come from the rear wing to make up the difference.

To aid this, McLaren have shaped the sides of the car to maximise the clean flow of air to the wing. The result looks pretty weird (the “L” shape sidepods; compare that with last year’s car, which had more conventional air inlets in the sides), but it’s absolutely logical. It’s a relatively small detail, and one that the other teams didn’t spot, but it’s a brilliant idea and a beautiful piece of engineering.

No idea whether it’ll work in practice though, as the car hasn’t been tested! Either way, it’s a very nice idea.

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China and Stuff

Monday 31st January 2011







Posted In: EngineeringPoliticsRant Tagged: | 10 Comments

Wedding, Water, Waffle

Tuesday 9th November 2010










Posted In: EngineeringMotorsportProcrastinationStuff Tagged: | 2 Comments