Professional Engineering

Silver lining for the skilled
The news coming out of the global automotive industry is not good, and there must be many automotive workers in the UK wondering what the future holds for them. While times are obviously tough, there are silver linings out there for skilled engineers.
Firstly, there will be a future for motor manufacturing in the UK. Demand will increase, especially for exports, now that the pound has weakened. Skilled engineers have been in very high demand and will be again once the current slump starts to abate.
Importantly, though, there are job opportunities for skilled engineers if they are prepared to work in other industries. This may involve some re-skilling, but in areas such as defence and power generation there is still an urgent need for skills.
Engineers must be prepared to be flexible, and relocation may be necessary. However, there is no reason why many can’t find employment elsewhere, with the government having a crucial role to play in supporting skills training for these people.
Only weeks ago we were worrying about a skills shortage. This underlying shortage still exists, so let’s make sure that skilled engineers leaving the automotive, capital plant, construction and domestic appliance industries are snapped up elsewhere.
Jonathan Lee
Stourbridge, West Midlands

Trust science, not instinct
It is an insult to the scientific literacy of its readership that PE continues to print nonsense such as Herbert Evans’ letter on atmospheric heat capacity (PE 12 November).  
Evans misunderstands the fundamental mechanism of climate change, which is the reflection, absorption and emission of radiation at different wavelengths by different gases in the atmosphere.
It is temperature, not heat, that drives evaporation (hurricanes, droughts), changes the solubility of the oceans (anoxia), and melts ice caps and methane-soaked permafrost (sea level rise, and more climate change).
Heat capacities are of course parameters in any dynamical model of a thermal system, and it is an appalling dismissal to suggest that climate scientists haven’t heard of the things. Here Evans has strained out a gnat and swallowed a camel: it is the oceans that provide most of the thermal inertia, not the air, and certainly not the carbon dioxide.
The willingness to arrive at grand conclusions from nothing more than engineering instinct, bypassing the vast stores of data, reams of analysis and years of hard work by a great many others, is a special sort of arrogance to which engineers are particularly prone. I take a contrary view of professional respect. I believe that climate science is complex, and should be attempted by those who are willing to read; that legions of climate scientists are not, in fact, on the make; and that my duty as an engineer is to find a way out of the mess very clearly identified by others.  
However, if the engineering profession prefers to follow Evans’ example, I will retrain as a plumber. At least then I won’t be embarrassed by the title.
Dr Alastair Martin
Edinburgh

We must behave like professionals
While complaining at the lack of (perceived) status of professional engineers, William Brunger also complains that he is no longer allowed, by law, to carry out tasks associated with specialist engineering trades (Letters, PE 12 November).
If Brunger (and many others before him) continue to insist that we be allowed to behave as tradespeople, is it any surprise that there is confusion as to the correct use of the term “engineer”, and that many tradespeople are given the label “engineers”?
As professionals we should, of course, have a good understanding of how many everyday pieces of equipment work, but it doesn’t follow automatically that we have the necessary knowledge and skills to carry out repair and modification without the appropriate (accredited) training and practical experience. I know how a Boeing 747 works, but I would never attempt to repair one!
Let me draw a parallel with another profession: I was taken ill in the summer and happened to be in the company of a couple of GPs and a couple of surgeons. While these professionals very kindly tended to my needs, they were perfectly happy to hand me over to the more appropriately trained and skilled paramedics on the arrival of the ambulance.
Status is an issue, but we have to behave like professionals if we expect to be treated like professionals. When my oil-fired central heating system needs servicing, I call an appropriately qualified plumber to service it – and I’m pleased that my salary as a professional engineer means that I can afford to do so.
Robert Hayes
York

Modern image welcomed
Will people stop complaining about the logo change? As engineers we are supposed to be continually improving and changing things. I am not for needless change but, as someone in their early twenties, I think the new logo really freshens up the brand and tries to promote that engineering is very much a part of the modern day, not some old and dusty practice.
Second, the cruise control argument. Several readers have pointed out that this raises fuel consumption, and that, by maintaining speed up a hill, the mpg will fall. However, if you assume that most drivers leave their foot in the same position, when they drive downhill they are going faster. So what mpg you may lose on the uphill you gain on the downhill.
Simon Stockford
Penwortham, Lancashire

Reflections on mirror drag
Bob Johnson argues that wing mirrors (more usually called door mirrors these days!) should be removed from car designs (Letters, PE 29 October). This would reduce aerodynamic drag, but not by as much as might be assumed.
For instance, on a reasonably aerodynamic saloon door, mirrors probably account for less than 2% of the vehicle drag; but this can rise to 6% for a large sport-utility vehicle (SUV).
In raising the example of the Aptera, the importance of not confusing the non-dimensionalised drag coefficient –
CD = FD/(½rV2A) – with the drag force (FD) is illustrated. The size of the object (in this case, by convention, the projected frontal area, A) must be accounted for in any comparison. So, when comparing vehicles of different sizes – or vehicles and door mirrors – the drag area (CD.A) should be used.
I estimate that the Aptera has at least 25 times the frontal area of a single large European SUV door mirror. On this basis, even with its remarkably low drag coefficient, it is likely to experience more than 10 times the drag force “caused by one big wing mirror”.
Adrian Gaylard
Chair, UK Automotive Aerodynamics Forum
Gaydon, Warwick

A bit of debunking is called for
Longstanding readers may remember that some 10 or 20 years back a sort of submerged paternoster with a series of bellows sealed by weights was debated at length. The weights extended the bellows on the side of upward motion and compressed them going down. Hey presto, energy for nothing from the imbalance of flotation!
The simple-mindedness of the scheme was quickly debunked but then, believe it or not, a lengthy debate ensued concerning means of eliminating the shortcomings before, mercifully, it was all put to rest with mathematics. Was it a joke? I am not charitable enough to allow it, so hopefully we shall be spared our blushes by not having a repetition.
Perhaps it will make us feel better to know that even top physicists nod: most if not all will have heard of the length contraction according to relativity, and that it is surrounded by several “conundrums”, one of which concerns two spacecraft connected by a cable in breakdown towing fashion.
As they accelerate to the speed of light, will the cable snap? At first airing among a group of the highest and mightiest, there was a split of opinion, although it is not recorded that blows were struck. A bit of lateral thinking, taking the steps from long, thin ship to long, waisted ship, to a waist thin enough to be a cord seems to be the way to approach it. John Major coined an appropriate if unfortunate phrase.
John Gayfer
Alcester, Warwickshire

Danger we must live with
David Clayton claims that “there is no safe level or threshold of ionising radiation exposure” (Letters, PE 12 November). Perhaps readers would like to consider these quotes from the BEIR VII report that he cites:
“The committee judges that the balance of evidence from epidemiologic, animal and mechanistic studies, tend to favour a simple proportionate relationship at low doses between radiation dose and cancer risk. Uncertainties on this judgment are recognized and noted in the BEIR VII report.
“BEIR VII concludes that the scientific evidence is consistent with the hypothesis that there is a linear, no-threshold dose-response relationship between exposure to ionizing radiation and the development of cancer in humans. And while this implies that even small doses have the potential to cause harmful effects, those risks at low doses are very small.”
Regarding non-cancerous diseases, the committee concluded that: “Radiation appears to increase the risk of diseases other than cancer, particularly cardiovascular disease, following high doses in therapeutic medicine and modest doses in A-bomb survivors. However, there is no direct evidence for increased risk at low doses and data are inadequate to quantify this risk if it exists.”
In other words, the available evidence does not disprove the “linear no-threshold” theory, but neither does it provide conclusive proof, rather a judgement that is subject to uncertainty. It may be that, in a truly radiation-free world, human life expectancy would be several hundred years.
However, since there is no escape from background radiation, and the dose from a nuclear power programme is minimal, why lose any sleep over it? No one can add a single hour to his life by worrying (to slightly misquote the Bible), but excessive concern about the odd micro-sievert could take years from it...
Brian Rowney
Manchester 

Nuclear switch-off
Your article about the substantial delays to the repair work being carried out on the Hartlepool and Heysham 1 nuclear reactors highlights the fallacy that it is only renewable sources of generation which provide intermittent output (News, PE 15 October).
The capacity factor of wind generation is chiefly dictated by wind resource and not technical reliability. My strong feeling is that it is more likely that the wind will blow between now and “early 2009” than that British Energy will finish their work ahead of schedule.
Chris Carless
Kintbury, Berkshire

Speaking up for ourselves
One good “scoop” requires another. The appearance on the BBC, in prime time, of an acknowledged expert advising the public about the future risks and opportunities for our power supplies, against the background of the IMechE headquarters, should have given some of the publicity we need.
This occurred on 12 November. I hope that this was, or will be, just a start to reusing the people of our profession through the media.
Albert Etchells
Inkberrow, Worcester