Daily GENERAL Mega-Thread [Oct 22 2017]

Daily GENERAL Mega-Thread [Oct 22 2017]

Welcome to /r/engineering's daily thread!

This thread is open to all questions, comments, and discussions, especially those things not usually permitted in normal posts:

  • Career advice questions
  • Job offer and job market discussions
  • Resume critiques
  • Office/management/employee topics
  • Questions about school/major choice/course electives (homework questions will be removed)
  • Discussions of current projects, including progress images
  • Pretty much anything you want to talk about that is engineering or job-related is fine provided you follow rules seven (7) and nine (9).

Submitted October 22, 2017 at 06:07AM by AutoModerator
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Daily GENERAL Mega-Thread [Oct 22 2017]

I had a dream today, and now I’m stuck…

I had a dream today, and now I’m stuck…

I want to take a few old 2 stroke engines, making a crankshaft somehow, and welding them together to create a multi-cylinder engine. I realized they're aluminum, and welding aluminum doesn't really work (I can't do it anyway). So now not only do I have to figure out how to connect the pistons, I have to figure out how to connect the blocks together.. Fellow engineers, help please…

Submitted October 21, 2017 at 07:27PM by Xbox360Dashboard2
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I had a dream today, and now I’m stuck…

Python Webcam Double Pendulum

Python Webcam Double Pendulum

Hello all,

I have an idea that I would like to implement for fun.

You can solve the equations of motion for a double pendulum, and the resulting behavior is really interesting and chaotic.

I think it would be cool to construct a small double pendulum and then record its motion using a webcam interfaced through Python. And then the recorded data could be compared to the analytic solution from Physics. Friction between the pendulum joints and air resistance is typically neglected. But is this a safe assumption?

Anyway, my idea is to make this pendulum and paint it black. Then I would paint the joint and pendulum weight white. Python should be able to read in the webcam images and then hopefully I can track the position of the pendulum joint by using some type of filter on the images.

I was curious if anyone had any advice or ideas about this project?


Submitted October 21, 2017 at 06:31PM by eternusvia
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Python Webcam Double Pendulum

Wikipedia article of the day for October 22, 2017

The Wikipedia article of the day for October 22, 2017 is Amargasaurus.
Amargasaurus was a sauropod dinosaur that lived in what is now Argentina from roughly 129 to 122 million years ago, during the Early Cretaceous epoch. The only known skeleton was discovered in 1984 and is virtually complete. Amargasaurus cazaui, the only species in the genus, was a large animal reaching 9 to 10 meters (30 to 33 feet) in length, with two parallel rows of tall spines down its neck and back. The spines, taller than in any other known sauropod, probably protruded as solitary structures supporting a keratinous sheath, and may have been used for display, combat, or defense. Alternatively, they might have formed a scaffold supporting a skin sail. A herbivore, Amargasaurus probably fed at mid-height. Discovered in sedimentary rocks of the La Amarga Formation, it is most closely related to the Late Jurassic genera Dicraeosaurus, Brachytrachelopan and Suuwassea. Together, these genera form the family Dicraeosauridae, with shorter necks and smaller body sizes than other sauropods.

Wikipedia article of the day for October 22, 2017

Drunk engineering student traces some really lovely pictures and defines what a plane is

Drunk engineering student traces some really lovely pictures and defines what a plane is

Not sure where to post this but I need to vent somewhere…

This story gets reposted all the time and every time people are heralding him as some kind of real-life Tony Stark. He's not, I have nothing against the guy but he didn't design anything and this whole thing has just been blown way out of proportion.

Here is an ekranoplan that bears a striking resemblance to his design. Compare this to this.

The "maths" he has done next to his design is completely meaningless as it is simply the drag and lift equations rearranged a bunch of times which are useless without knowing the values of the Lift and Drag coefficients which can only be found accurately by simulation or by building a physical model (Also, as far as I can tell he doesn't even take the ground effect into account which is kinda the whole point of ekranoplans).

I've seen a couple of people say his math checks out in terms of statics; all he says with regards to that is "lift=weight" and "moment to counter moment". Yeah, that's how a plane works; but, in terms of design, it doesn't mean anything especially when you don't know the values of any of the forces.

That is literally all this story is; A guy came back to his room drunk somehow manoeuvred his way to the ekranoplan Wikipedia page clicked on the link about the ekranoplan in the first picture on the page. Made a couple sketches of that, copied down the drag and lift equations from his textbook, and then wrote some vague or meaningless shit over it.

Yet this story made international news and is now reposted all the time and still gets thousands of upvotes. Can we please let it die?

Submitted October 21, 2017 at 06:10PM by tcs36
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Drunk engineering student traces some really lovely pictures and defines what a plane is