Almost any piece of engineering is more complicated than it appears to the untutored eye. That is as true of a single component as it is of a complex system.
Whereas the engineer may discover ways for a component not to perform as she designed it, it is also vital that a system be studied with its many components interacting. The engineer may find that, in a system, every component may behave perfectly in itself yet still those components interacting may give problems.
System engineering is is an important subject and many engineers wrestle with and study the performance of complete or partial systems. It is very difficult too.
It is a fact of simple statistics that many components interacting offer many, many possible combinations of ways to go wrong or just not perform as planned. That also means that it is so very easy to imagine what it is that is giving the problem. Beware of getting fixed on such an idea: for it can just as easy for it to be wrong.
The Lad’s car was losing water, but only a certain volume – not all of it. Then there was the strange bubbling in the coolant tank. On hearing this, the garage mechanic said that’s probably a leaking header tank; that model is prone to it. OK, some things now seemed to hang together. The garage ordered a new header tank. Took a few days as it had to come from abroad. That with the labour costs as well took it to about £150. Drove off. System still leaked.
Then we looked – instead of making such an easy, unexamined assumption. It wasn’t the header tank. It was the radiator. Ooooohhh Noooo. Not one our finest moments – not the way an engineer should do it. The seemingly significant point that not all the coolant disappeared – but only a certain amount – was not significant at all. Only a little disappeared because we were checking frequently – it would all go eventually. Radiator replaced and problem solved!
Comet 1 – The face of triumph and tragedy.
On a much more serious level but many years ago, was the Comet crash problem. When one crashed losing many lives, they held an enquiry. Wreckage was inaccessible at the bottom of the Mediterranean. The designers developed several ideas for the possible cause and designed ways to put each right. The Abell Committee concluded that:
“Although no definite reason for the accident has been established, modifications are being embodied to cover every possibility that imagination has suggested as a likely cause of the disaster. When these modifications are completed and have been satisfactorily flight tested, the Board sees no reason why passenger services should not be resumed.'”
The Air Safety Board concluded that:
It realises that no cause has yet been found that would satisfactorily account for the Elba disaster…… Nevertheless, the Board realises that everything humanly possible has been done to ensure that the desired standard of safety shall be maintained. This being so, the Board sees no justification for imposing special restrictions on Comet aircraft.
Sixteen days later another Comet crashed in the Mediterranean taking with it all the passengers and crew. There was fatigue failure between two openings in the top of the fuselage that had not been considered.
The authorities did not know what the cause of the first accident was but let the aircraft fly again with passengers. Hindsight is a marvellous thing but The Lad believes that the authorities should only allow an aircraft to fly after a crash
WHEN THEY KNOW THE CAUSE AND THAT THE PROBLEM IS PUT RIGHT
Is this too strong? Do the current Regulators follow this principle?
A small machine needs a continuous supply of oxygen. Chemistry is too complex. Why not pull it from the air all around us. No shortage of raw material.
Absorption (a) and adsorption (b) mechanism. Blue spheres are solute molecules.
Chemists tell engineers about adsorption [see diagram] Note though, that our process b) is gas to solid not liquid to solid as shown Nitrogen gas clings to some fine powders. Pass air over the powder; nitrogen is trapped and out comes pretty pure oxygen.
But there is a problem, so the engineer comes up with a clever solution that is not science but quintessential engineering.
Concentrated oxygen gas is needed for many uses in the modern world. Industrial processes such as steel making, engineering cutting, medicine and others need vast tonnages of the stuff. Modern steel production needs oxygen by the tonne; as do many large-scale chemical processes.
This school chemistry toy process of potassium chlorate or hydrogen peroxide is not going to give that. Engineers use cryogenic air separation to extract it from the air. For this, in simple terms, air is cooled down till it is a liquid and then very carefully allowed to warm up and at-196C [if it is at atmospheric pressure] the nitrogen boils off leaving, the liquid oxygen (which boils at -183C) behind
On a slightly smaller scale it is needed for oxy-acetylene cutting torches and supplies for whole hospitals. Here, although still produced cryogenically, it is distributed to customers in enormously heavy, forged steel bottles.
On a smaller scale still, many people with breathing problems need extra oxygen to live. They need pure oxygen all the time in a form that they can breathe. Sometimes, for use by one person it comes in quite small bottles say only about 20cm long but, even so, it is still quite heavy to carry for any length of time.
Similarly, extra oxygen is needed to keep the transplant liver of the recent post alive throughout its journey, be that 2 hrs or 30 hrs. Machine portability also meant low weight was very important. Doing it cryogenically would be too heavy and power hungry.
The answer for the engineer was an oxygen concentrator using adsorption.
The fine powders have an enormous surface area for the gas to cling. But air contains a staggeringly large number of nitrogen atoms. When the area is coated by nitrogen, more nitrogen passes through and contaminates the oxygen stream. It must be regenerated to free the old nitrogen.
But for an hour of oxygen, chemists tell us we will need an enormous heap of powder. This is possibly acceptable in a large plant with room for a big machine: but not for continuous oxygen for a liver transplant machine or an ill person to carry.
This brings us to the crux of the problem. Either we arrange a heavy container of a very large quantity of powder to give us long life before oxygen supply stops for regeneration. Or we have a small light container of powder that has a short life before oxygen supply stops for regeneration. Apparent stalemate.
The engineer’s insight was to use two very small containers at the same time. Air is pumped through the first container of zeolite powder until the powder is saturated and nitrogen comes through. So we stop using the first and start pushing air through the second. While the second is doing its job, the pressure in the first is dropped and the powder regenerates by releasing the nitrogen it has adsorbed. Then when the second is saturated, the first is now ready to take over and the second can regenerate.
So it is that small, light containers can produce a continuous supply of oxygen. Here is a good graphic. Now that’s engineering!
Without going into a lot of detail, absorption is that to absorb one substance within another. An example is of sugar being absorbed into a cup of coffee and being very difficult to separate again. Adsorption, on the other hand, is where one substance clings, fairly lightly, to the surfaces of another. Some say that, although not seen by The Lad, if a cube of pressed carbon powder is dropped into a glass of dyed water the colour will be removed as the dye clings to the surfaces of the carbon powder. But, crucially, this process can be relatively easily reversed: vigorously shake the glass of water and carbon and the colour will return to the water. This is regeneration.
Engineering is one of the three drivers advancing the human race. This blog describes professional engineering in the real world as 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.
At the back of many of these posts lurks the definition as well as the name of the engineer. From the earliest posts to the more recent , The Lad implies a definition of what makes an engineer and what does not .
The core is that the engineer works with the various forces that exist in nature to turn them to the advantage of all humanity. At first, the ‘forces’ aspect seemed to be sufficient. Then recently he saw a newspaper [what else?] carry a picture of roustabouts on an oil platform and called them engineers. It is clear that they are vital workers, but, although central to the oil industry and estimable for their herculean work in terrible conditions, to all except the media they are not engineers.
Such proud men probably do not call themselves ‘engineers’.
Why not? For aren’t they are wrestling with those natural forces in the massive rig and drill steelwork and the weather? Not half! Something similar can also be used to promote car mechanics to the ranks of engineers. A spanner and a hydraulic car lift certainly consist of natural forces, don’t they? They surely do.
The definition of the engineer, as The Lad knows her, needs to reflect how the roustabout and the mechanic are not engineers.
The mechanic and the roustabout do not design the equipment on which they work. This is the crucial difference.
The posts also implied that the benefit ought to be to all humankind. There are two difficulties here. One is to ask who knows whether an engineering artefact is really a benefit to all or only to some and also whether, in the long or medium term, it could damage. The other is that the engineering may be of benefit to some that are not of humankind. Think of a salmon ladder in civil hydraulic works or modern enclosures in a zoo.
Let us leave out Humankind. Let it stand as ‘benefit’ with the implication of ‘as best we know and can’.
So! Here we have it.
Update, June 22, 2013 – Realised that essential Production Engineering is not subsumed in the definition. To clear this most succinctly, the word ‘forming’ is added
Engineering directs for benefit any or all of the processes of imaginative conception, design definition, forming or analysis of devices or structures that use any of the forces acting in the universe.
3D printing is appearing more and more often in the media. Admittedly, it is mostly in the more excitable screeds, but nonetheless a lot of people see it as a game changer. But then they would: writing about it makes media content to sell. A more technical name is stereo-lithography. This gives a clue as to how the idea works. It is like printing slightly different images on successive sheets of paper from your printer. Cut out each image and stack them up and glue them together and, lo, you eventually get a solid shape.
This is how the 3D process works. Image thanks to Materialgeeza.
Some internet enthusiasts claim that it will let anyone make anything and everything in their office or even their bedroom. “Buy nothing ever again: just copy it from the internet.” They are apparently almost wetting themselves in their excitement.
Others on the other side of the divide forecast the end of the world as we know it. Anyone will be able to make guns from freely available data files from the internet. Horrors! Even that device has to have at least one metal part – the firing pin. Made from a nail, since you ask. The Lad would be wary of going near to such a weapon being used, let alone lifting it near to his head and firing it at someone Wouldn’t you be wary of it exploding into a myriad pieces like an old blunderbuss? Or even one part splitting under the propellant forces, taking your face with it.
The fact that 3D printers currently cost a fortune and are large is the central problem at present. This may not always be the case though; they may follow the same path as computers whose prices dropped like a stone over the years. The picture is of a simple machine.
This is a simple version of a 3D printer. Image thanks to Bart Dring
Actually the idea has its uses now. No doubt more will appear in time. Because it is expensive and fairly slow and available only in a small range of not very capable or strong materials, its main use is to produce models of hardware straight from CAD designs on the computer. Prototyping it’s called: making model parts without complex machining set-ups.
OK. Let’s get down to the nitty-gritty-the essentials. Yes, it’s engineering again. It’s all about the material of the parts. How much of your world is made of plastic. Yes, quite a lot but nowhere near everything. Even in your computer, the heart of the nerd’s world, much is made of metal especially the strong, structural parts and the electrically-conducting parts. Most load-bearing things everywhere are metal. Of those that are not, the majority are composite materials; not yet possible stereographically. Also, see the gun firing pin mentioned above. Many of those metal parts have to be heat treated too to give them enough strength.
The Lad’s view is that it is likely that the process will be a nine-day wonder like fluidics. What is fluidics? A previous erstwhile Great New Technology that came to very little. Ask any engineer active in the Sixties.
The last post told how customers, scientists and engineers interact. This is the story of the engineer.
The surgeon and the scientist asked the design engineers, Team Consulting, to design and make a machine to do the job in the real world. This was to become the OrganOx® metra™. The finances meant the prototype must be operating in 9 months.
Stuart Kay, Project Manager, led the engineers’ design team. There was a lot to learn about the problem.
“[The customer] had some outline user and product requirements,” Stuart told The Lad. “ and knew what the basic fluid circuit needed to be like, there were a lot of verifiable requirements that needed to be un-earthed in order to ensure that [the customer and designers] had a common understanding of the end goal.”
To avoid problems later the Project Manager always writes a Design Specification. This records all the many dimensions, operating features and power requirements.
In existing transplant technology, the liver sits at 4˚C without nutrition or oxygenation for up to 12hrs. Some livers have features that mean, although they are otherwise perfectly usable, they cannot be cooled like that and still be re-used. Cooling can itself sometimes damage a healthy liver; and, during its journey, certainly no one can tell how well it is surviving.
The new technology keeps the liver at body-heat, ‘feeds’ it and supplies it with oxygen. This alows more livers to be usable; they last for up to twice as long and can be checked for survival during the journey. In simple terms, the plan is to keep the liver beavering away outside the body doing what livers do inside the body, while it was being moved. That way we can even measure that it is doing a digestive job properly.
Any design of a machine using body fluids has special problems. Blood can clot on surfaces or be damaged in a pump. Everything must be kept absolutely sterile. These problems are not new though: some have been overcome before by designers of heart-lung and dialysis machines. So they save time and money by using existing, proven pumps, valves and pipework. All wetted parts are single use and disposable to keep everything sterile.
The blood circulating has to have quite a lot of oxygen as it is used up by the liver. Normal, steel, bottles of compressed oxygen are too heavy. What’s to do? Extract it from the air as we go along-that’s what. The existing, brilliant, engineering idea of a Concentrator leads to a much lighter assembly. That will be another post soon.
The machine has to feed, preserve and monitor the health of the liver. Firstly, there is the rather beefy power for the pumps and heater; and, secondly, the delicate listening and sampling systems checking the performance of the liver. The electronic system engineers have to take great design care that the great, bouncy, power supply does not electronically deafen and interfere with the sensors.
Then there is the system engineering. The engineer cannot just plan to have all the components bolted together. She has to think clearly and deeply about how to get them to work together. Standard parts may need ‘tuning’. As a very simple example, think of a system full of liquid that has a standard temperature-measuring switch for a standard heater. If that system contains a transplant organ, a simple switch off at the right temperature could result the organ temperature overshooting or undershooting. The engineer may have to arrange always to switch off a little ‘early’ or a little ‘late’. Only this way can the possibility of damage to the transplant organ be avoided.
This kit does not sit lazily in a laboratory; it has got to be moved safely from hospital to hospital. There must be not the slightest damage either to the system or the payload. It all has to fit into one trolley with a protective shell. They designed an elegant transport and protection frame which is lowered into a neat, tubular chassis with castors.
The designer has to decide how best to manufacture machine parts, and, vitally, how the technicians can service the machine to high standards. As Stuart wrote to The Lad, “The only way to achieve this is with a dedicated and highly skilled engineering and design team, and we had one. We hit the 9 months target, and the system worked beautifully.”
All in all, this is a marvellous piece of engineering. If this stuff appeals, remember that you, female or male, could join such a team.
The Lad is grateful to Stuart Kay, Project Manager and Team Consulting for their informative help. Top notch engineers.
Engineering is one of the three drivers advancing the human race. This blog describes professional engineering in the real world as 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.
Here we have a job lot of three, small but egregious media errors.
Spyker
There was a piece in the paper on one of those wild sports cars that are either never built or only half a dozen are claimed at around £1Million each.
It is called the Spyker B6 Venator. Designing a car-any car-involves defining the details of engine, suspension, body and chassis, transmission, electronic control and much else besides. That is a massive, engineering task.
Victor Muller claims to be the designer of the Venator. It appears that he started as a lawyer and since has been the owner of several firms ranging from marine salvage to fashion. Not impressive qualifications for a car designer.
That designer claim is probably only as valid as that of a child drawing a car. “It’s got a really big engine … y’know; lots of small wheels… er, machine guns at the front and … a boot full of footballs.Yeah!”
It sounds like an ego-driven dream.
Miranda
The other day Miranda Krestovnikoff, a zoologist and usually reliable TV presenter, had a piece on learning from other species. How do those little tree frogs cling to a wet leaf? Not only that, they can then stop clinging and off they walk. Marvellous.
Miranda spoke, on The One Show , to Professor Anne Neville, of Leeds University, who told us she is investigating how the little creatures do it. This splendid skill could let a tiny machine that she and her team is designing cling to a surface inside the human body and even move around. Such a device could carry a video camera to show a surgeon using keyhole surgery exactly what she is doing as she works.
Our zoologist called Professor Neville and her team, ‘scientists’.
No, they are ‘engineers’. Professor Anne Neville is a qualified and very senior engineer and is Chair in Tribology and Surface Engineering, School of Mechanical Engineering. Check her out. If this is called a quibble, then The Lad must ask if a zoologist would be embarrassed to confuse a shark and a dolphin.
Engineers design machines and scientists investigate the natural world. Engineers designed the system and created the valves in Miranda’s SCUBA gear and scientists investigated nitrogen in the blood and wrote the diving tables she uses when diving for TV.
Solid smoke
It’s maddening. Engineering is mostly ignored, but then, when it does come up, it is often treated like this. This is an example of Bower Bird syndrome [attraction to shiny baubles]. I am sorry but it was The One Show again. It’s nothing personal; just the limitations of the sad, viewing habits of The Lad.
Advocates claim the name Aerogel for a weird type of stuff. It appeared in an item on unusual materials fronted by Marty Jopson. Marty comes over-as always-with an engaging screen presence and calls himself a ‘Science Bloke’ and started out as a props designer.
Aerogel is a remarkably low density foam hence its nickname of ‘solid smoke’. Marty marvelled over it and gave one of his demonstrations. Now these are normally very enlightening and very interesting. This time, he showed a small block of the foam with a chocolate resting on the top of the block. He lit a blow torch and passed it underneath and played the flame on the bottom of the block for a few seconds. The Lad has to be honest: he did not time it but can assure you that it was, undoubtedly, shown on screen for no longer than 15 seconds. Glass fibre insulations blanket could, probably, perform similarly.
Perhaps you have never heard of the ‘solid smoke’ before? No? The Lad had but is not surprised. He had assumed that it had been invented somewhere around the 1980’s. Looking into it he was surprised to find that its precursor had been invented in the 1930’s – over 80 years ago.
Why have you not heard of it? This engineer will tell you why. It is because it is useless. Now, now Lad, don’t exaggerate: it has been said to have been used in those hotbeds of value-for-money – NASA spacecraft. Many years have passed without a job. It is one of those curious things that are sometimes tagged as a “Solution in search of a problem.” Note that the only organisations making it are universities. The Lad has been unable to find a single commercial organisation offering the stuff for sale.
Next Time
Look at real, valuable engineering innovations instead. One is the OrganOx matra which is the subject of my next two posts. Do not allow yourself to be led by the nose to marvel, uncritically, at space-filling items either journalistic or foam.
Boeing 787 Dreamliners are still grounded around the globe in February 2013 after the lithium ion battery problems became very bad in January 2012. Boeing says currently that it expects the aircraft to be back in service in late March or April. Something similar, but on a smaller scale, has happened before with laptops bursting into flames because of their lithium ion batteries.
This is the sort of problem that an engineer can face when any of her creations takes to the sky or arrives in numbers in the big, bad world. It may an aircraft, a car or a washing machine. It is what sometimes comes after the creative struggle of the Design process. Of course she hopes that the problems are not too terrifyingly large.
Now here, though, we have dozens of planes grounded for months and each worth two hundred million dollars [according to the Boeing website]. Nonetheless, dealing with similar things on a smaller scale are part of his job description for any engineer.
What information that seems to have seeped into the public prints is that the Lithium Ion batteries have not been adequately cooled and have taken fire. This is not something that aeronautical engineers want to happen to their babies. The aircraft designers or their colleagues, the Power Electronics Engineers, will be looking to see if some fault external to the batteries was the cause or whether the batteries installation has been designed too close together or whether the cooling systems designed for them are not sufficient.
The Lad is not a battery design expert, but he knows that lithium ion batteries are more like little furnaces rather than the EVEREADY, zinc oxide dry-batteries of his boyhood ‘tin’ torch. We can discover that like a boxer, pound for pound, these batteries are six times better than the standard lead acid battery in a car. This feature is gold dust for plane design engineers. But as a consequence of this, the lithium components are bursting with energy and therefore can get very hot. This, together with the essential [but flammable] solvent, means that a battery if it is hard-driven is continually on the verge of losing control to a runaway reaction and getting either very hot or even bursting into flames.
If it is a battery cooling problem for a modern airliner the solution will not be simple. No one can just say let us move them apart from each other or away from other bits of kit so that then they won’t get so hot. An aircraft may look large roomy and smooth from the outside.
An early DreamLiner at Farnborough Air Show
In truth, inside there is packed a 3D maze of structure, engines, fuel tanks and cargo…sorry, passengers. Below is a picture that gives an indication of the complexity of the structure even before all the rest of the kit is installed.
An early Production Engineering Test Rig
Agreed! It is not a very informative graphic but it is the only one that seems to be available. Remember, that the Dreamliner has much clever engineering to allow the use of vast amounts of non-metallic components in its structure. How they do this is a close Boeing secret and not one they are likely to share with anyone in public anytime soon.
Certainly, the plane will be crammed inside with frames and stringers between which the batteries will be shoe-horned into their position. What is to be done then in these jam-packed spaces? Currently, rumour has it that
“Boeing has proposed insulating the battery’s lithium-ion cells from one another to prevent fire spreading, encasing the battery in a fire-proof shell and installing sensors.
It also proposes a venting mechanism to remove fumes which led to the emergency landing.”
The view of The Lad is that this can only be seen as a ‘workaround’ rather than a definitive solution which should involve arranging for the batteries not to over-heat. We can only await events.
A final thought on those ‘events’ is that, if the experience of The Lad is anything to go by, major problems like this will be astonishingly more complicated than The Lad is able to deduce in this post. The points that he makes above will only be the beginning of the beginning.
Such problems will have a large team entirely devoted to solving them. Such a team will consist of dozens of engineers. There will be design and development engineers, metallurgists, electrical and electronic engineers. As a team, they will be working, certainly, seven days a week and probably 24hrs a day. That’s what engineers do: their best efforts sometimes produce a problem so then they have to race to solve it. All the while that they struggle, massive present and future costs result in cash haemorrhaging straight down the drain – to waste.
Note that, while Boeing may say all will be well by March or April, at least one major customer airline expecting to be without its planes till May. So – that the above Boeing team list does not include the groups of programme guys working at the airlines. They are struggling to arrange replacement flights for passenger already booked to fly in planes are no longer available. The costs of this group and plane hire will undoubtedly land on the Boeing doormat in due course.
It emphasises that the professional engineer must always work with not only the obvious factors of ‘materials’ and the ‘forces’ developed by the machines but also with essential factor of ‘finance’.
How about this thought though. Problems such as this Dreamliner may be exhilarating – provided no one thinks that you were to blame. If you are in charge of the team solving them, The Lad guesses, that it can be satisfying. So! If you are the person who says ‘Bring it on!’ then maybe you are a worthy successor to Isambard Kingdom Brunel.
Sir James Dyson is famous for his engineered products and support for UK engineers and engineering. It is striking that this has come about from his work entirely devoted to domestic appliances. A few years back, The Lad would then have expected that such an engineering reputation would have had to have stemmed from Defence or Aerospace or Power Generation: industries that are awash with finance, opportunities and Research and Development (R&D) departments. Perhaps, alternatively, anywhere in Germany or the US – but we won’t go into that.
The air moving device, called the Air Multiplier by Dyson is one of his latest devices and, typically, it is a remarkable example of thinking laterally. That, together with painstaking development, brings a device to replace and improve the standard domestic fan.
The vacuum cleaner newly bought by The Lad is the DC41 Animal . As part of normal usage and maintenance of the cleaner; the internals brought into view reveal an engineering, tour de force of die cast plastic design.
That vital component of the engineering design process, the material, used by Dyson is presumably that marvel of an engineering plastic – ABS or a more modern derivative.
However the new design cleaner is not without minor glitches. Such glitches though, The Lad emphasises are part of a normal engineering development of even the highest level product. There is also a much more interesting effect that we will come to after a mention of the glitches.
The On/Off power switch has nowhere near the snap action [as in a light switch on the wall] that this user expects. A stab action of the finger frequently leaves the motor still running. That’s one. The other concerns the power flex, or cord. It is longer, which is good, but is not so easy to handle as was the flex of The Lad’s previous Dyson. It does not coil in the hand comfortably. Possibly the insulation elastomer is slightly too stiff in shear or there are inbuilt stresses. Either could lead to torsional coiling problems.
Now we come to the interesting thing.
Think about this. The Animal cleaner is definitely a more elegant engineering design than the products of other companies and also its Dyson predecessors. Also, the design morphology is different in that the filters are in different locations in the air flow path. Despite this, the design is now back to the starting point. This starting point was a vacuum cleaner with a bag [which is a filter of course] that had to be changed; the dust collection efficiency declining if it was not.
From the user’s point of view; which has to be the engineer’s Gold Standard, things are now much the same as they were. Dyson recommends washing the 2 filters in the Animal every 3 months. Their extraction is as inconvenient as was changing a bag and the washing of the filters and their 24 hr drying time [perhaps longer in winter in the UK] is more inconvenient.
So here we are. This is a vacuum cleaner design that demands that its large filters have a 24 hr maintenance process to avoid loss of efficiency. The clever and elaborate cyclone technology is being overshadowed by the old [paper in one case] filter technology. One of the filters is in the shape of a bag. Sir James had better not let his engineers go any further down this design branch!
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.
Here is the return of The Lad after an absence from cyberspace caused by an egregious failure by a new ISP. Let’s not go there; at the moment, at least. It is only a short comment on the first programme in a new series on BBC 1 called ‘The Genius of Invention’.
The first thought on looking at the title, was the familiar hobby-horse of The Lad: it’s not invention or inventors [or scientists – on another day], stupid, it’s engineers. Hold on a moment, though. It is perhaps not necessarily engineers who discover and investigate natural phenomena. It may, and often is, scientists like Faraday or even gifted amateurs who come up with the goods. So, let’s not go down that road this time. Let them have it as a title.
OK, now the programme. Visually and technically it was pretty good. Graphics that The Lad saw of the ideas behind the Newcomen and Watt machines were excellent.
With James [steam condenser] Watt at its centre, this edition promises well for the following three programmes. Each of which has at its centre one of Frank [jet engine] Whittle, Michael [electric power] Faraday and Charles [turbine] Parsons.
Fronting the presentations was Dr [medical not PhD] Michael Mosley. His ‘wingmen’ were Dr Cassie Newland, University of Bristol industrial archaeologist, and finally, thanks to the Gods of TV Commissioning, an engineer. This was Professor Mark Miodownik, engineer, materials scientist and Professor of Materials and Society at UCL. A skewed team; no doubt the producers think it rakish. So: not encouraging.
Moving on, though. At least it was set in a real place, Drax Power Station: currently the biggest coal-fired power station in the UK and providing 7% of the power for the whole of the UK on its own in this one place. It is a place that is both real and important in the everyday world and in engineering terms. Sadly the first real person representing engineers was in overalls. And male. He probably does wear them though for his work as he was the overhaul manager. Notice that. He was not the design engineer or the manufacturer.
The vast size of the building and the scale of the ‘set dressing’ imposed themselves on the viewer. It should give pause for thought for any “small is good” advocates. Consider the magnitude of the task for small scale power generation to replace this place and be a significant solution to power generation in the modern world. That is nearly 4000MW for 24 hrs a day, every day.
The distant views of the presenters talking to their cameraman was a bit gimmicky but at least it gave an idea of the scale of the Drax hardware that surrounded them and are part of the world of the power generating engineer.
The dalliance with a large Drax stop valve lost a bit in translation being as the hardware was lying on its side on the floor. Its height, The Lad guessed, was at least twice that of the human beings, if not more; a striking image that simply did not appear.
Yes, you are right. The Lad is jealous. Oh to be able to direct such forces toward his take on engineering on a prime time, main stream, TV channel.
The next programme is devoted to Speed. It will, one imagines, introduce Frank Whittle at least. Certainly Rolls-Royce will continue with another of its recent starring roles on TV. Money could not buy this advertising exposure.
The handbook says check the oil with the car on the level. On holiday: everywhere nearby was sloping a little. Sure enough: at each place the level on the dipstick seemed different. His Irritated hunt for somewhere suitable gave The Lad ample time to reflect that the measurement of the amount of oil in an engine seemed remarkably low-tech in this day of high-tech engineering,. It’s like having to use your finger in the dark to find out how much beer is left in the glass.
What does the engineer demand that the oil do in a car internal combustion engine (ICE)? We will come back to that question.
Most other features of the ‘driving experience’ are either electronically governed or satellite mediated and unlikely to be less so any time soon. What is it about the oil? Even that most complex and technically advanced of power plants, the gas turbine aircraft engine, has a sight glass. That is, arguably, less advanced still than the dipstick.
By definition when the engine is running, oil is distributed throughout the engine and there is instrument power enough to measure pump pressure. But pressure does not vary with the amount in the engine. Until it is too late, that is. How are you to discover how close it is to running out? Firstly, the engine designer has to send the oil to one place to give us the chance to measure it. Clearly, it can only be allowed to go to that one place when it hasn’t got anything better to do elsewhere. Only when the engine is stopped can the oil go for its roll-call.
But when the engine is stopped, we cannot afford any significant, power drain from the battery; neither for pumping oil to a tank, nor for a powered measuring instrument. There is only one force to do the jobs. So, gravity it is.
The roll call takes place in one place: that place is in a container at the lowest point where gravity can be relied upon to drive the oil. To save space under the bonnet and give suitable ground clearance, this container will be relatively shallow, probably wider than it is deep. If you have ever tried to carry water in a shallow dish without spillage, you will know how difficult it is. The liquid is very eager to migrate to one end or to the other.
As an aside, it is worth showing how some things are important over a wide range of engineering affairs. In another part of the engineering forest, this liquid behaviour, called the ‘free surface effect’ is also very important to naval architects who are designers of ships. For them, in tanker ships and ferries the free surface effect is not just an inconvenience: its management is a matter of life and death. In 1987, 188 people died and many more were injured in the Herald of Free Enterprise when it capsized in less than 4 minutes after sea water entered an undivided, vehicle deck.
The engines that power most cars and trucks on the road are reciprocating ICE engines; that is those with cylinders with pistons in them. The Lad has never been involved in their design. However, as an engineer, it became clear to him that this eagerness to migrate to the ends of its container is central to the dipstick problem. It is this that means that the dipstick level is different when a car is on the level or on a slope.
Is there a position then that means the variation with any slope is small or, at least, as small as possible? Yes there is. The Lad set up a toy demonstration of this effect. Below is shown a container with three [not very clear] red marks at the liquid surface. First, the surrogate tank is level and each red mark is at the liquid level.
Model Oil Tank on the level
The views expressed in this post are not necessarily those of Kempe’s Engineers Year-Book. No engineering book was harmed in this demonstration.
Now if we tilt the ‘tank’ down at the left as if the ‘car’ was on a slope, what do we see? The liquid level rises above its left hand mark and sinks below its right hand mark. Not surprising.
Down at the left
The next image shows the effect more clearly.
Down at the left enlarged
Now, tilting the ‘tank’ down to the right; the level on the left falls below its mark.
Down to the Right.
The point that we are making here is that levels measured close to either end of a tilted tank vary significantly. These images show [although far from Wallace and Gromit standards] within their limits, one important effect. There is one place to measure where the tilt has no effect. It is half way between the tank ends.
So: we see that breaking the liquid surface midway between the oil sump sides is the best place to site the dip stick. Then any slope will have no effect on the measurement.
Clever, eh? So, there we have it. The student interview syndicate answer! Right!
Wrong!
Here is the dilemma. How do we make it accurate in a real engine? The dipstick cannot go anywhere you like. It has to take account of the engine structure for one thing. The pistons and cylinders and valve camshafts tend to get in the way; not forgetting all the rest of the components, large and small, that pack the engine compartment these days.
Now The Lad is not an ICE specialist and the above is naive perhaps or too simple. So who would know?
The UK company, Ricardo is one of the foremost specialist ICE designers. They have been engine designers for nearly 100 years, working on a very large number of projects, Their market has included defence, motor sport and marine. They worked as part of teams with General Motors and Chrysler of the US to design a class-leading V6 engine capable of global implementation for GM and, for Chrysler, the Dodge Viper engine upgraded to 8.4 litres and a massive 600 horsepower for the ultimate muscular American sports car.
Ricardo engineers work on driveline and transmission system engineering. There have been cost-optimized manual transmissions for developing markets and advanced and high performance systems such as the dual clutch transmission of the Bugatti Veyron.
In short, they are proper engine designers; not ICE dilettantes like The Lad.
A Ricardo engineer put it this way. The dip-stick provides a rough estimation of oil levels in the sump but it’s not necessary that this is wildly accurate. We can tolerate the effects of slight changes in pitch/roll of the engine in comparison to the acceptable level between maximum and minimum recommended fill which is very large. In practice the dip stick is usually placed mid-way along the engine but again, this isn’t particularly critical provided that oil level is being checked on reasonably level ground (as specified by almost all manufacturers).
During the engine design, as the Ricardo engineer put it, the design engineer knows that it is essential that he or she ensures that there is enough oil capacity and enough oil circulating to maintain sufficient cooling to avoid overheating the bearings. These days, oil coolers are also commonly used for this purpose, especially in hot climates or where the vehicle is working under extreme loads (e.g. towing in mountainous areas).
During engine operation, the crucial consideration is that there is oil at an acceptable temperature available at the pump intake when the engine is operating – this will typically be drawn from around the lowest point on the circuit. On the other hand significant over-filling should be avoided as this only causes wasteful churning and possibly some oil reaching the combustion chamber. The quantity of oil specified for a given engine is not an exact science but a compromise based on the above comments – usually erring on the conservative side.
There, now, you really do have it!
The engineer’s emphasis was that these are the key points in the mind of the ICE designer; not agonising over the height to a mm of the oil surface. Good ideas, even clever ideas, are not enough. Engineering for the designer is to have, backing her up, real experience of the components in the gritty world. The engineer is always pragmatic at heart and the real-life solutions are usually complicated and not always tidy. Engineering teams, like Ricardo and others like them at the top of their game, have this experience. If you want to be an engineer, seek them out.
If you are really in difficulty finding a level surface, there is an approximate solution. Check the dip stick with the car facing one sloping way, then turn the car till it is facing in precisely the opposite direction and note the dip stick again. Half way between the highest and the lowest is a good reading.
You would be right but only partly so if you said the job of the oil is to lubricate bearing surfaces. An equally important task is the cooling of the core components of the engine that external coolant flow cannot reach.
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’. The Lad is entirely independent of any organisation mentioned. The target of the blog is the career seeker and the general public.
