The first 7:53 of this video is all about orbital mechanics - which is interesting, I'll grantcha, but isn't the focus of this blog.
If orbital mechanics is your jam, go play some Kerbel and get back when you reach an expolanet.
We're here to learn about material science, and that's where the video takes a big turn at about 7:55, first exploring the carbon foam composite of the solar shield, itself, and the ceramic, reflective paint on its sun-side.
Then - at 9:15 - we get into the solar probe cup and its measurements of the solar wind. The big issue there is that the cup can't hide behind that carbon-carbon composite shield. It has to survive nakedly in the solar wind at 1400 degrees C which sort of limits the acceptable materials. The conductive mesh is made of acid-etched tungsten, and the wires leading to and from the mesh are a niobium alloy called niobium C-103 (89% Nb, 10% Hf, and 1% Ti) with sapphire bead insulation...you know, as is tradition.
Space is frickin' wild, man.
And that doesn't even get into how we tested those materials - a whole other journey that's covered after 13:55 in the video.
The first four minutes or so of this video are about the economics of 3d printing with metal and why it is - for now, anyway - restricted mostly to just prototyping rather than mass production.
Then there's a bit of coverage about testing 3d printed parts - particularly in fatigue strength - as compared to traditional machined parts and a bit of explanation as to why their fatigue strengths tend to be significantly lower - including a micrograph exploration of metals while they are sintered . It's surprising to me that there isn't - at least shown - an example of a sintered piece of metal being tested.
Overall, the video is a nice exploration of why mass produced engines will likely not be made by 3d printing experts in the immediate future.
This is another overly long video that is filled with a massive amount of science in all sorts of disciplines: physics, material science, chemistry, engineering, mechanics.
The video sees the Real Engineering host, Brian McManus, visit SpinLaunch's centrifuge being built to launch satellites into space primarily via kinetic energy rather than through rocket fuel combustion...which sounds totally bonkers but might work out.
One of the main technologies here involves a carbon fiber-reinforced polymer tether. At 3:00 that concept is explored with a laminated carbon fiber reinforcement mock-up of the thickness that they need the tether to be to hold the millions of pounds of force that would be necessary.
Then - 8:00 - they look at the need to spin up that tether in a vacuum chamber so that it doesn't melt the carbon fiber from the friction due to air resistance. They also describe how truly low pressure vacuum chamber pumps work and why the SpinLaunch people don't need a vacuum chamber with quite that low a pressure. The idea of outgassing from the metallic parts - 10:25 - was amazing to me. It makes sense to me that there would be small amounts of oxygen gas 'dissolved' in any steel parts, but I had certainly never thought about it before. It's an equilibrium problem, I guess, as oxygen is removed from the atmosphere around the part.
At 16:20 they take a look at the challenges of opening a low pressure chamber at near vacuum to the atmospheric pressure outside without destroying the chamber inside when the air rushes in. They've used a pairing of mylar layers that are broken through and two incredibly quick closing doors.
From 21:30 they explain how they address and minimize vibrations - especially once the payload is let go, leaving a highly unbalanced weight on the arm.
The next section - from 26:45 - they look into the ballistic coefficient of the projectile and why a heavier vehicle might be better for their launch process - something that is very well against the traditional method of launch's goals. With rockets, lighter is better. With the SpinLaunch, heavier and denser is somewhat better because it allows the projectile to gain more momentum without corresponding drag and heating due to friction with the lower atmosphere.
The whole process is fascinating, and I'm hopeful that it turns out to be feasible because I would love to see a full scale SpinLaunch facility built and functioning - for the science and novelty if for nothing else.
This video didn't answer the question I was thinking it would. I was thinking it would go through the economics of why the Concorde no longer flies. Instead it went through the failure analysis following the only fatal Concorde crash, that of Air France 4590 on July 25, 2000. That does appear, however, to have been the nail in the coffin of the Concorde's commercial life.
The first five or so minutes of the video introduce the crash and the beginning analysis. At 5:00, then, the first clues emerge in the form of a sound recording of a burst tire and a remnant of irregularly-drilled metal strapping among the wreckage. At 10:00, the materials testing gets into fracture mechanics to determine how and when the fuel tank ruptured.
This might not be the best video to watch if you have a fear of flying, but it's fascinating to see how much can be discovered from how little was recovered.
I recognize those material selection diagrams at 1:35. I've posted about similar diagrams before.
This video does a great job exploring the tradeoffs among strength, weight, cost, and properties in choosing a material. In this case, it's mostly about the tradeoffs guiding when we do - and don't - use titanium.
It also covers some of the concepts of chemical and electrolytic reduction around 5:00 - and states that we don't use either of the traditional processes to purify titanium. It's amazing that anybody ever figured out some of the more complicated metals processing...um...processes. They're so remarkably complicated.
We also get an application of accidental galvanic corrosion at 8:30 where the cadmium-plated tools were leaving trace amount of cadmium on the titanium.
Titanium really sounds like a pain in the tuchus to work with.
In case you were wondering which science- or material science-themed YouTube channels I subscribed to, you could probably just skim back through and see which video sources I post from most frequently.
But I thought I could put together a list in case you wanted to subscribe to them, too. So, in no particular order...
Smarter Every Day - Hands down, my favorite channel on YouTube. Destin Sandlin is an engineer turned YouTuber who covers a whole host of science topics both high brow - How Do We Land on the Moon - to low brow - How Do You Harvest Pecans - and covers them all with a humility, curiosity, and ease of communication that is infectious. Occasionally he gets a little too excited about things (check his collaborations with Mark Robert, for example), but most of the time his tone is spot on, and I learn something from nearly every video that he makes. Most tend to be ten to twenty minutes, but occasionally he post forty-five minute to an hour videos and takes a far deeper dive into a topic - take his nuclear sub series, for example. You could easily turn his videos into a year-long science course. I'd take it. He also has a second channel of slightly less polished videos and lots of behind the scenes footage. Destin also spoke at Skepticon about balancing his faith and his science. It's a great talk. His TED talk isn't bad, either. (equally for both blogs)
Real Engineering - Initially this channel from Brian James McManus (yes, he's Irish) focused mostly on the rudiments and basics of engineering and used a lot of white on blueprint paper background animation. He's upped his video quality and started using a whole lot more licensed footage over the years, and he now tackles some pretty deep dives into engineering topics (solar panels, renewably powered ships, tesla's battery challenges, colonizing the moon, digital vs vinyl sound, etc). Videos tend to be in the 15-25 minute range anymore. We almost never see Brian, himself, though there have been a couple of videos where we did. I learn a TON from his videos at this point. Initially, I didn't learn nearly as much. (more for MatSci blog)
Practical Engineering - Grady Hillhouse reports from his house in San Antonio and makes civil and mechanical engineering incredibly understandable. Some of the best parts in his videos are his small-scale, homemade demonstration aids to help him explain the video's concepts. He's built tiny rivers to show how weirs function, made rebar-reinforced concrete cylinders to show how they improve concrete's resistance to cracking, crafted complex pipe systems to show water hammer, and much more. His videos stick to the 8-12 minute range, and are great explanations of basic engineering concepts. (more for MatSci blog)
Veritasium - Dr Derek Muller hosts - and probably writes - the veritasium channel videos. He originally did all the work himself, but one of his more recent videos celebrating his tenth anniversary on YouTube talked a bit about his increasing team helping him make videos of higher and higher quality. Muller comes out of Canada by way of Australia and is all over the map as far as topics go. His videos are about optical illusions, origami engineering, calculating the speed of light, close packing with shade balls, and - my absolute favorite video of his - how trees get their mass. He covers chemistry, biology, engineering, physics, and general philosophy of science. (equally for both blogs)
Steve Mould - Steve's videos are far less focused on any one area of science (or of math). He covers everything from "I calculated absolute zero with vodka" to "Tree tumors are GMOs but not made by humans" to "Self driving cars are dangerously confused by LED lights" to "Does Canadian money really smell like maple syrup?". He's a bit of all over the place, in other words, wandering pretty much anywhere that his curiosity happens to take him. The initial videos were pretty low-budget and short (1-4 minutes long), but the quality of video made a pretty big jump about five years ago. The videos have gotten longer over time, some of them wandering to the fifteen minute range, though he still makes a decent number of videos that are in four or five minutes long or shorter. (equally for both blogs)
Mark Rober - Mark's all about building bigger, more theatrical versions of everyday things. He's build a scaled up SuperSoaker, filled a pool with jello, and set up the world's largest elephant toothpaste (or devil's toothpaste). He's also built machines to skip stones better than humanly possible, squirrel obstacle courses, and a liquid sand hot tub. Admittedly, most of his videos could be cut by about 25% of their length by eliminating the over-reaction shots. I think his best videos are the most focused. I particularly recommend the rock skipping video.
I find myself digging the shift that has taken place on the Real Engineering channel.
Brian McManus - the host of Real Engineering - has been putting in a ton of work to step up the video's quality and the content's depth. I find myself learning a whole bunch of new stuff in every video that he's posting.
In this one, McManus details the reasons that the solar energy striking most photovoltaic solar cells is only turned into electricity at a lab-tested 20% efficiency - and even lower 18% real-world efficiency.
This is due to light being reflected, the threshold energy necessary for silicon to release electrons, heat build up, adding metal contacts which block light hitting the cell itself, oxygen defects in the silicon wafers itself.
...and there's some awesome explanation (along with animation) of how p-type and n-type semiconductors are used to produce voltages in solar cells.
The Real Engineering videos do tend toward higher level concepts nowadays, but they're brilliantly cited and clearly explained.
Was the Mars Rover really lowered down by flying platform and hooks and winches?
That's kind of awesome!
We get to see the reveal of the memory metal 'tire' at 4:10 in the above video, a mesh tire made of what looks like a chain mail of nitinol. Then there's a great explanation of why nitinol is a super-elastic material (using our old friend, the stress-strain curve) and some nice atomic-level diagrams.
Then we get a bunch of close-up video of the wheel deforming and returning to its original shape.
The rocket animation shown around 1:00 looks pretty hokey to me, though the concept is pretty outstanding.
I was speaking to a former student of mine who now works as an engineer in the aircraft industry. She said that one of the major issues with the carbon fiber laminates being used in airplane bodies nowadays is going to be the lack of recyclability after the plane's usable lifespan.
In this video we get a brief history of how carbon fibers are made, the initial uses of and driving forces for development carbon fibers, an explanation of the directional strength of the composite material, the general procedure of curing the laminate, and a quick look at SpaceX's use of carbon fiber composite laminate in its reusable fuel tank.
It lacks a bit in the 'how it's made' first steps, but it's a great overview of how carbon fiber works, its strengths and weaknesses.
There is something weird happening with the Real Engineering guy's accent. I'm struggling to place it exactly. There's a sing-song lilt to it that's screaming, "Irish" to me. Then, at 1:50, there's a weird ll-th thing going on with the 'through the heat treatment process' phrase that makes me think he's almost got Welsh in there. His patreon page says Galway, Ireland, but I've not heard that ll-th thing anywhere but from Wales.
So much great metallurgical explanation here...BCC, FCC, ferrite vs austenite vs pearlite, phase diagrams, quenching vs tempering vs annealing (normalising - British spelling, natch).
