Mercenary Engineer

One of my classmates from undergrad coined the phrase mercenary engineer in place of mechanical engineer. At the time, about to graduate, we were all desperate for employment and opportunities. After years of being sold the bill of lies that is STEM recruiting we'd all felt certain we'd have secure and financially rewarding employment very soon. Whether it was all oversupply or just effects of the recession everyone had become a little less picky and us mechanical engineers were willing to work pretty much anywhere doing pretty much anything. Will engineer for pay.

 

One of the reasons I went into mechanical rather than electrical or structural or chemical was how diverse the field seemed to me to be. Don't get me wrong there's a lot more to sparkies than I realized at the time. But whether you're developing a box for one application or another a lot of the design can be the same if you're working within your specialty. I knew mechanical engineers worked in the auto industry, industrial manufacturing, wind power, mining, aerospace and aviation, space, defense...you name it! Developing one product can be wildly different from another. I liked that kind of variety though I'm sure it's not easy to jump between industries. So I thought my classmate's description of the mechanical engineer was pretty apt: a broad set of skills and an engineer willing to work in a lot of different fields.

 

The picture is a miniature from Reaper Minis and is Rosie the Chronotechnician.

Mechanical Engineering Employment and Pay

Continuing this week's theme of jobs jobs jobs for all you hardworking engineers, I was curious what the outlook had been in my own discipline. I already covered employment and salaries in most disciplines between 1999 and 2010 but wanted to zero in on the mechanical engineers.

Mechanical engineers have had a bit of a bumpy past. The general trend is up but it hasn't been easy. My personal theory for the boost is that the wars in Iraq and Afghanistan have acted as stimulus programs for mechanical engineers. Our own Works Progress Administration putting us to work building tanks and humvees and fighter jets and bombs. The first major climb lags us entering the wars but is pretty strong. I give the delay to the delay in starting Department of Defense contracts and actually funding companies.

Maybe the post 2006 boom is due to the surge (I'd have to look it up). Trends in the automotive industry could also be strongly responsible as well as oil drilling, coal mining, etc. I think the strength even in the recession shows the numbers benefit from more than just commercial development alone. For comparison I pulled the civil engineer's chart over the same period of time.

So same boost up from about the same period on. This one has got to be thanks to housing. The quick and consistent line up and the drop right at the housing crash has had a big effect on the employment of civil engineers. How about our friends the sparkies?

It ain't easy being a sparky. The dot com bubble burst and it hurt. A couple of little climbs later and the recession hits and they are knocked back again. Still, given how heavily commercial electrical engineering is it's probably got a much more sustainable path to growth than defense dollars and government bailouts of the auto industry. Something to keep in mind.
Next a quick look at pay for mechanical engineers:

The bottom line is inflation adjusted. Without that the skyrocketing wages look pretty crazy. But even with inflation engineers managed a 10.5% increase to their mean annual salary over the last ten years. What? You're probably thinking. I'm a sprocket and my salary hasn't been going up. Could be what with the recession and choosey employees they're more likely to hang on to somewhat older and more experienced engineers in lieu of hiring younger ones or keeping young ones on. That may not be the personal experience of older engineers, but even if we're taking very minimal trends it can add up. And 10% increase over 10 years for the gain of 10 years of experience seems kind of like a bargain on the employer's side of things.

Still, the war might be to thank (or blame) for the strength in mechanical engineering employment. ME employment is up over 15% from 1999. Despite the bust civil engineers are employed at 19% more than 1999. And as you can see in the graph electrical engineers broke just about even (actually a drop of two tenths of one percent). I don't think engineers should go into a field based on national numbers and national salaries. Locality can make a huge difference. And of course it's important not to chase money but to do something because you think you'll enjoy it.

Engineering Employment Over Time

How has engineering fared as a career during this recession? How has it been doing over time? Must be jobs week here at Design. Build. Play. Since I was so hard on software "engineers" before I made a separate category from today's Bureau of Labor Statistics data. I'm including programmers separately (but still there) from computer/software engineers (which here includes both systems software and applications). So how do we engineers do?

As you can see computer and software engineers have done particularly well. I'd grant the decline to programmers as being employers are ever more demanding specific degrees from their programmers so it's more just a transfer between categories. The recession has only continued the downward trend from before.

In comparison, civil, electrical and mechanical look almost flat. Of course they aren't really. So maybe you went into engineering for the money, how's that been doing? Here's some not adjusted for inflation salaries over time.

Again it's the same breakdown by discipline and again you see the obvious levelling off of the programmers' salaries. Mechanical and civil seem tied like in the previous graph and now electrical has a definitely higher salary. Is this because it has lower employment compared to the other disciplines as seen in the first graph? Does scarcity drive electrical engineering salaries up?

Engineering Jobs by Discipline

I talked before about what states are hiring engineers and where all the engineering jobs are. Best estimate there are something like 44,000 engineering jobs open nationally right now. The census says that in 2008 84,000 people graduated with engineering degrees. Engineering shortage? I think not. Probably my 44,000 search was not broad enough to include the kinds of jobs engineering graduates might go into. But still, that's nowhere near a shortage, is it Corporate America?

So what kind of engineers are being hired right now? Software engineers.

Making up almost half of open jobs software engineers have it made. If we have a shortage of engineers, maybe it's that kind of engineer. The problem is we're recruiting people into a very diverse field without specifying what we really want or really need. I was curious how this stacked up to major choice and pulled a some numbers from a local university to give a breakdown:

You can tell mechanical and civil/structural majors are heavily overrepresented. People are probably going into these fields and finding the jobs aren't there. This is all magnified when certain geographic areas (Detroit vs Silicon Valley) have very different focuses even when colleges might be more diverse. Chemical and electrical engineering majors are a little closer to the national average of open jobs and software/computer engineering heavily underrepresented.

I'm a bit torn by including software engineers here. There's a big difference between "computer engineer" and a programmer. Many job openings ask for a degreed engineer when what they really need is a programmer. But if they're asking for an engineering degree that becomes a part of the requirement that job seekers have to meet even when it's unlike other engineering disciplines. Given the low numbers though it's possible those with other degrees, or no degrees at all, are filling the gap for these open software jobs. That is if anyone is even hiring.

Design Fridays: Volvo's new flywheel

Volvo's claiming their new flywheel design will be able to give a four cylinder the equivalent of six cylinder power as well as save 20% of combustion energy.

 

A flywheel is just a name for a rotational device that's able to store energy. It does this by using inertia and saving rotational energy. The amount of energy that can be stored is based on the moment of inertia and rotational speed, where moment of inertia is based on mass and radius of the wheel. Typical flywheel designs might include differing weights at certain points in the wheel that help keep the rotational speed more consistent and higher.

 

In your typical automotive application, a flywheel sits on the end of your crankshaft and converts the energy and movement of the crankshaft into a more consistent rotational speed.

 

Volvo is claiming that their flywheel will be able to store so much energy that when the engine is idling it can actually turn off and the energy stored in the wheel is enough to start combustion again. If so that could explain their 20% fuel savings number as engine idling is a well known waster of energy (why electrical cars and the Prius shut off at a stop). The flywheel also sounds like it is using aspects popular in hybrids and electric cars: regenerative braking. There've been a lot of attempts to incorporate regenerative braking into designs, the idea that you can get back part of the energy you're wasting to brake. But generally these designs haven't been efficient enough to be practical (plus once you add complications, you add more room for failure, and the more components the heavier your car thus reducing your energy savings).

 

They're supposed to start field testing this sometime later this year.

Future of Spaceflight: No single point sollution

Too often we look for a single perfect answer to our problems. In the energy crisis people are often disappointed when hybrid batteries are found to be so environmentally unfriendly or that wind power is often incredibly harmful to local bird life or that solar cell arrays often use a lot of water in areas that are pretty arid to begin with.

Researchers looking into the future of space flight looked at combining a rocket propellant with an electric sail. An electric sail has some similarities to a solar sail in that they are both low mass propulsion systems however a solar sail uses the acceleration of photons to create slight accelerations to the apparatus while an electric sail uses an array of long, thin positively charged tethers that repel solar wind protons while attracting solar wind electrons. These arrays have all been proposed as a method of space flight that would require no additional propellant as accelerating and decelerating more mass requires more wasted energy. However an electric sail would only function in space and the gains to acceleration can sometimes be minute.

The researchers used the Hohmann transfer numbers as a starting point for interplanetary travel between Earth and its neighbors. Typical planet to planet rendezvous would include a period of time where the spacecraft was accelerating to give it a necessary velocity delta to escape Earth's orbit, then a period where it would coast to reach the orbit of the planet it's attempting to reach. Minimum flight times were calculated for this basic transfer orbit as between 0.289 years to reach Mercury and 30.613 years to reach Neptune.

The authors looked an ideal thrust-on time in comparison to minimum flight time because while shortest flight would generally be ideal you would also want to reduce your thrust time in case of your propulsion system failure. So it was better to look at a ratio between the two. They looked initially at having a secondary thrust phase after an initial coasting phase but found using the total time and thrust time ratio meant it was always optimal to have only one thrust phase followed by a coasting phase.

Their initial starting point was an object in circular orbit around the earth to which they then simulated times it might take that object to reach planets in the solar system using either a typical rocket propulsion system or the hybrid rocket and electric sail option. In the first option the rocket propellant and inertia allow it to reach the escape velocity. But in the case of the electric sail, the sail's acceleration can contribute during the thrust time towards achieving the delta velocity which of course reduces the amount of propellant the spacecraft would have to carry. I summed up their results in a slightly more clear graph.

Perhaps not surprisingly flights to Mercury and Venus were worse with the hybrid system. Though, an electric sail only system would save considerable fuel and mass and could be considered to Mercury and Venus. The major time savings were seen the farther out into the solar system. The hybrid system doesn't solve long term space flight concerns but it does add another weapon to our arsenal that perhaps future spaceflights will employ multiple methods of propulsion.

Quarta, A., Mengali, G., & Janhunen, P. (2011). Optimal interplanetary rendezvous combining electric sail and high thrust propulsion system Acta Astronautica, 68 (5-6), 603-621 DOI: 10.1016/j.actaastro.2010.01.024

Humanoid Robots

Or how foolish scientists will open the doors to Skynet and a future in which we run from robots trying to kill us. Perhaps literally so. Boston Dynamics, who brought you the infamous "Big Dog" robot (here's a video) have been in the news this past month for the DARPA funding of their new cheetah robot. Supposedly the thing is designed to chase down human prey. Luckily in CAD form it looks less menacing so far.

I have been thinking about the Uncanny Valley in robot design lately. I like Disney's Wall-E and of course I'm waiting for this KeepOn robot to go on sale so I can purchase him and have more moments of squee in my day. But then robots go past the divide. There are plenty of scary looking singing Japanese robots out there. Even a German company has gotten into the race with their "fembot" that can lift things and do factory work. [As an aside, I hate how we have to sexualize all our robots. "Dude-bots" are not called "man-bots" or whatever, if it looks male it is male and the difficult and that doesn't need to be mentioned. In this case I'm not even sure why the AILA was given some approximation of plastic human female hair and vaguely human female curves. Reminds me of the exec in 30Rock complimenting Liz Lemon on being "a good businessman." "You mean businesswoman?" "I'm pretty sure that's not a word."]

While Boston Dynamics was busy making a robot that would hunt down human prey (I'm not sure what kind, or why...terrorists? illegal aliens? Convicts when we finally implement a "running man" or "the gamer" type of future where falsely convicted hero-types must compete for their freedom and lives on a gladiator-like gameshow that bloodthirsty Americans just eat up?). You might have missed their introduction of a bi-pedal robot, ATLAS.

Boston Dynamics already has a two-legged robot, and the video is seriously creepy. It doesn't help ATLAS looks like a freaking Terminator but imagine it walking around non-chalantly like their existing robot Petman and you'll see what I mean with uncanny divide. When the operator shoves him to the side (see me using masculine pronouns for this thing? dammit) I really expected the robot to finally go psycho after being pushed around one too many times and kill the guy.

It's only missing a nice big HAL light on the front of it. So sure Boston Dynamics I'm impressed. But I'm also creeped out. I'm going to go back to watching your snake robot and this weird climbing robot that looks like a lizard. I bet audiences in the 1980s seeing the movie Terminator for the first time wondered how stupid humanity could be that it created the thing that became self aware and destroyed us. But now I see it! We'll make them for coolness factor! Coolness factor is going to be humanity's downfall. Good thing my fallout shelter doubles as robot defense shelter.

Imposter Engineer

Despite coming from the generation where supposedly every kid got a trophy just for participating I am not an overly confident person. Don't get me wrong, I am confident in who I am. Thanks to a family that raised me right, no adverse or unstable conditions in my childhood, and now a good support system of that same family, my husband and some friends I feel good about who I am. But when it comes to what kind of engineer I am I have a strong case of imposter syndrome.

Regardless of what level of success they may have achieved in their chosen field of work or study or what external proof they may have of their competence, those with the syndrome remain convinced internally they do not deserve the success they have achieved and are actually frauds. Proof of success is dismissed as luck, timing, or as a result of deceiving others into thinking they were more intelligent and competent than they believe themselves to be.

The engineers whose intelligence I admire come from a mix of backgrounds. Some from prestigious schools, some from less so, and still more who never got a degree but you would never know it based on their top notch job performance. Sometimes I see people at my age and career path who seem to possess a better working knowledge of the equipment and I begin to question why I am even here.

Only occasionally am I surprised in the other direction. I wrote just yesterday about my struggles with report and technical writing only to be surprised today putting together a report with some of my fellow students. Granted I have a lot more experience writing reports than they likely do, but oftentimes I am impressed with their previous knowledge and experience (some a military background) as well as their creativity and innovation. However none of this made them good writers and their portions of the report were unclear and not persuasive.

So I spend a lot of time checking out books from my university library (while I still have access) and reading up on what I wish I knew more about, the thing my group does primarily. Still I don't feel this provides me with the instinct and hands on knowledge I respect from my superiors. And yet, though I feel my university gave me a good theoretical background I've seen other students from the same university and at about the same career point able to grasp theoretical workings of the equipment much faster than I can. So I know there are two paths I need improvement on.

Sometimes I wonder if I'm just not good at this. That perhaps my sparkling personality (you didn't see that coming did you) or mere determination is the only reason I'm still here. It would explain a lot of the unfair treatment I get. At other times I wonder whether I am more competent than I realize, though possibly less so than the people I compare myself to. Other times I wonder if I am excelling and just don't realize it. Then I swing back to thinking I am incompetent and a below average Engineer. One small benefit of working on an interdisciplinary team is how it exposes you to what you do know and other engineers don't. And that's one of the nice things about being surrounded by sparkies (that's EEs) on EngineerBlogs. When they talk about something electrical or build something amazing it doesn't bother me as much because I'm not an EE and I don't feel as bad by comparison. It's more a fun experience of learning a little about something I didn't already know. If only I could apply the same attitude to my own discipline.

A welding robot for all those hard to reach places

Many of the challenges in ship building or ship maintenance stem from environmental concerns: from the seemingly minor in not wanting ship material or ship waste to enter to the ocean to the obvious preventing future spills or catastrophic failures like the Exxon Valdez. One of the solutions to making liquid-cargo ships more resistant to failure is a double hull design.

When major disasters like mining disasters or situations like the gulf oil spill occur one question people often ask is why we still have humans doing these dangerous jobs. And that comes into play with the welding necessary in assembling a double hull ship design. The space welders have to be in to do their jobs are very small with floors and girders blocking them in and the areas can get extremely hot during the day. All this combined means the work can be extremely dangerous to the people involved. Attempts have been made before to design welding robots that could do the work in place of human workers.

Welding carriages exist but these are limited by often being able only to operate within a few axes of motion. Larger and more flexible 6-axis machines exist but the overhead devices needed to hold these robots don't fit within the confines of a double hull structure. The authors of the study found a viable commercial option that is small and lightweight and able to operate within the small area required but still unable to make the important u-shaped welds often required in these spaces due to limited control and degrees of freedom of the robot.

The designers took the leading commercial welding robot design and came up with some additions to optimize it. One issue with getting the welding robot into the space is the small size of the access hole combined with a heavy and large robot can make it near impossible for human hands to guide it in. They developed a bridge plate that supports the weight of the robot and along with two winches would allow two workers to move the robot in and out of the access hole.

The final design uses both driving wheels on the floor along with passive wheels for guidance overcoming previous design weaknesses that relied on driving wheels only and could not move as accurately with dirt and debris on the ship floor. The rails it drives along fold up to allow it to move in and out of the closed space. It contains a six axis welding manipulator, comparable to other high end commercial devices, along with a sophisticated controller and positioning device. Six AC servo motors (encoders) are directed by a four layered logic modularized controller in the CPU.

Designers also reduced the size of the hand held controller needed to operate the robot as well as adding in the capability of it communicating wirelessly with the robot rather than via a cable. In the end they reduced the time required to weld, still met satisfactory welding standards, and based on field testing have some ideas for future design.

As in many other applications, some of the best developments come out of combining previous successful designs or seemingly slight improvements to the existing solution. This is also one case where field testing proved incredibly useful and I'm sure we'll see some interesting follow up from this study.

Lee, D., Ku, N., Kim, T., Kim, J., Lee, K., & Son, Y. (2011). Development and application of an intelligent welding robot system for shipbuilding Robotics and Computer-Integrated Manufacturing, 27 (2), 377-388 DOI: 10.1016/j.rcim.2010.08.006

Design Fridays: That's a big prop

The small UAV market is smoking hot. Boeing has a high altitude long endurance (HALE) they'd like to sell to someone. And they're not exaggerating in taking on the HALE acronym, it can reach an impressive 65,000 ft altitude and supposedly stay aloft for up to four days. It's doing some final ground testing now before actual flight testing commences so we'll see the truth in their claims rather soon. Powered by two engines it will also have two really big propellers. 16 ft in diameter big. It dwarfs the not insignificant 2.3L engine that powers it. Here's a video of their ground testing with the prop:

I'd like to see the prop map on that. What's a prop map you ask? Well when designing a propeller the contour of the blade lends itself to a certain efficiency at certain airspeeds and altitudes. There is no one blade that will work for every aircraft so you take a known propeller and its efficiency curves and map it out into little efficiency islands.

Then you can take this information and figure out where your aircraft would perform and how efficiently the prop is doing at various airspeeds and altitudes (air density is what's important here) and compare how efficient your prop is at your max takeoff speed or at your high altitude cruise speed as in the table below.

Given Boeing's Phantom Ray has two engines and two props I wonder if the redundancy allows it to stay up in the air if one engine fails like many larger military or passenger aircraft. At the least I think this is the start of higher expectations for UAVs where once 20-30 hours was considered an endurance flight I expect that will be too short of flight time going forward.

DARPA Thursdays: Underwater Sensors

A lot of DARPA's interesting marine projects relate to anti-submarine warfare, like this pilotless ship I talked about last year. Now they're looking for an underwater sensor array. I've done some quick CAD of what this might look like, as seen in the photo above. Underwater arrays are nothing new. They can look like buoys, capsules floating underneath the surface, they can even be disguised in something that looks and floats like kelp.

Here DARPA has in mind something that would be in deep ocean, at or near the bottom. This brings to mind my rough idea for a series of pressure resisting domes you could drop to the ocean floor. Sensor arrays are kind of a neat thing to begin with, a bunch of nodes communicating with each other and sharing information. So its a two fold problem of designing something that's mechanically hardy in not only high pressure environments but also cold, corrosion and have to be long lasting or incorporate some clever mechanism to surface itself and be easy to replace.

Working in the ocean is not unlike working in space; you can send your hardware into it but if something fails it's best to have as many possible methods of fixing it from a distance as possible. Meaning communication between nodes and to your surface point would not be trivial. And by the way the FBO is written you can tell DARPA's not looking for amazing innovation, they're just looking for something that works. Seems like a good opportunity for a small interdisciplinary unit to make something effective.

Designing the Collapsible

For my senior project one of the big challenges is trying to flatten the thing we are designing. There are a whole lot pieces of technology out there, though one doesn't traditionally think of using it to fold structures, but in this case that's what we're looking for.

I started off with McMaster Carr, my favorite one stop shop for the discerning mechanical or manufacturing engineer. I'm waiting on an order right now, with a press button incremental hinge, an adjustable friction hinge, and a lever lock hinge.

But another great way to get some inspiration is by heading to your local hardware store, or even your local outdoors/camping store. We found a slot hinge used for folding a chair which was something I had considered. Only problem is our structure is not very large, and these act like a brace in the corners so it can take up quite a bit of room.

We also found a rounded hinge that was used for a camping table and the spring wire/slotted structures that you usually see on pop up tents.

My favorite find, however, was the radial hinge from a jogging stroller. If you can picture the collapsible top of a stroller with rounded supports that allows it to fold close almost like an accordion you can see where this radial hinge fits in.

There's something to be said for looking to the latest research or the most new and advanced manufacturing techniques but there's also an advantage to checking out basic consumer products that are already out there and seeing where inspiration strikes. You never know what simple mechanism did not occur to you in your hunt to optimize your design. Of course, this might be a bit too simplified if you're dealing with a failed water pump or something a bit more complex but if you're thinking for a prototype don't be afraid to stop by your local hardware store just to browse. You never know what you'll see.