The topic are largely the same, though this one goes more deeply into how NiTiNOL works on the stress-strain curve and how the deformation of NiTiNOL is an autenite to twinned martensitic crystal transformation - complete with some nice animations.
It does also mention that the crystal transformation are exo- and endothermic (17:05), something that I don't think I've seen mentioned in other videos. I admit that if hot water is necessary for the martensite to austenite transition, it must be endothermic, but I haven't seen anything demonstrating that transition being both noticeable with bare hands - and a large enough NiTiNOL sample - or via thermal imaging camera. Neat detail there, doctor Derek.
Admittedly, the fact that their first launch wasn't fully successful isn't anything to look at as a failure in my eyes. The fact that the first launch failed is sort of the benefit of the 3d printing process. One of their supposed benefits is the fact that the engineering cycle will be sped up, allowing iterations to happen in far more rapid succession than was previously possible.
So, good on ya, Relativity. I look forward to seeing your 3d-printed metal rockets in space someday soon...just not yesterday.
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.
Richard Feynman wrote (or said in a lecture - I'm not sure which), "when the atoms in contact are all of the same kind, there is no way for the atoms to 'know' that they are in different pieces of copper. When there are other atoms, in the oxides and greases and more complicated thin layers of contaminants in between, the atoms 'know' when they are not on the same part."
But two metallic pieces that don't have those thin layers between them - primarily because they've been in space and rubbing against each other - can spontaneously weld together to become a single piece of metal.
It's possible to get that to happen on Earth, but it's not easy because of all the pesky oxygen we have around us all the time.
Metals are way weirder at the quantum level than we think they are, man.
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.
Grady is back to school us about those tiny 'sparks' that flew away from the launch pad when SpaceX's rocket launched in November 2020.
Apparently the concrete that SpaceX uses for their launch pad isn't quite the same as the concrete that sits as the walkway outside my classroom window.
Grady explains what concrete is (hydrated crystals) and then tests two types of concrete exposed to three heat environments (room temp, home oven, and propane torch) under compression strength tests.
Not shockingly, the heated concretes broke at way less force.
He then goes on to explain how most of this weakness is caused by our old nemesis: thermal expansion.
There's a part of me that looks at this video's tour guide like he's from the Parks and Rec Grizzyl offices. I know he's probably brilliant - his wikipedia article certainly suggests so - but it's like Dr Derek is getting a tour around a rocket factory from a teenager.
This is another video where I spent much of the time with my mouth agape once I realized how revolutionary this method of production could be if they get all the hiccups worked out. The process seems like an extreme of the 'build it fast and wrong, then build it again and better' style of prototyping and manufacturing.
If you have the time, compare this video in which rockets bodies and engine parts are 3d printed from aluminum and alloys to the old-school rocket manufacturing tour from Smarter Every Day. I don't know which is better, but they show radically different approaches.
I'm willing to watch just about the most mundane bit of nothing if it's being done in space because nothing happens in space the same way that it happens here on the surface of Earth.
On Earth, two metals put next to each other stay fairly distinct from each other. (I don't want to hear about your dendritic growth causing shorts.)
In space, however, metals spontaneously weld to each other if the metals are in close enough contact because any sort of oxide layer - immediately formed here on Earth pretty much no matter how well we polish the two surfaces - simply doesn't form. As Dr Derek paraphrases from Richard Feynman's lecture, "when the atoms in contact are all of the same kind, there is no way for the atoms to 'know' that they are in different pieces of [metal]."
Seriously, space is so totally foreign to our experiences.
The quick version is that Destin (of Smarter Every Day) shows us his tour of United Launch Alliance (ULA with their CEO, Tory Bruno. The ULA factory has some pretty highly-regulated manufacturing going on.
I'll go with a bullet point list of things I found interesting and possibly useful for a material science class. Admittedly, the full video - fifty-four minutes long - is probably more than any class could watch in total, but it's got some awesome clips.
5:15 - The video cuts to avoid filming "that" to Destin's left and right, items that Tory narrates but that he says flatly can't be filmed and shown.
7:15 - Quick discussion of the supply chain for the aluminum sheets that the rocket fuel tanks are made of
8:30 - We see the finished product of a machined isogrid panel as well as why that design - not the ideal design - was chosen because of the limitations of FEA analysis calculations in the 1990s.
9:50 - Discussion of the safety margins in space flight (1.1 - 1.25 times designed load) as compared to those of land-based transportation (7-12 times designed load)
12:15 - Amazingly, we get a mixture of, as Bruno says, "the pinnacle of technology...high-tech, robotic operations but mixed in [with] craftsmanship with people who are very skilled and have great attention to detail." That's amazing that something this precise is partially done by hand. This will come back in a bit.
13:30 - Machining, subtractive manufacturing is mentioned...as well as their recovery system for recapturing the aluminum chips for eventual recycling.
17:00 - 19:20 - Advertisement for Audible, skip it
19:30 - Replacing the isogrid with an orthogrid, saving time and weight, along with a quick discussion of strain and work hardening that happens by hand after the machining. We get a nice close-up of the orthogrid at 21:10.
22:00 - Destin uses the term strongback to describe the construction of the press used to curve the machined panels. That's a term I had to look up.
22:45 - Destin questions whether the aluminum is annealed, and Tory says they allow the aluminum to artificially age at room temperature after they are slightly work hardened from the curving process.
24:15 - Back to manual manufacturing to a precision level that - according to Tory - can't be achieved by automation. "You will always get better results by doing it by hand," he says.
27:30 - We see the anodizing facility to create a thick oxide layer for hardness and corrosion resistance. I knew that bare aluminum automatically formed an oxide layer, but I hadn't heard - as Tory says around 28:10 - that the natural layer is very thing and porous, leading to poor corrosion resistance.
31:30 - I wonder what the various acid concentrations are.
32:10 - We head toward the friction stir welding area, and Tory explains why friction stir welding is the better choice for strength of their final tank.
34:05 - Destin 'peaks over there' at a highly pixelated area. Cute
36:00 - Quick explanation of why it's better to order one large pizza than to order two medium pizzas
37:40 - Another pixelated section with the specialized head of the friction stir welder
40:15 - We switch over to stainless steel - half the thickness of a dime - instead of aluminum as we switch from boosters to upper stages.
43:00 - We get a finished view of the 5m composite payload faring and a discussion of ULA having brought the manufacturing of that from Switzerland to north Alabama via business partnership.
44:00 - Bruno discusses ULA's record of flying both payload and actual people successfully with 135+ consecutive, successful launches.
45:20 - Discussion of mass fraction (without explanation)...I had to look that up, too.
46:30 - Changes coming from hand arc welding to automated welding in the next version of Centaur (the upper stage) to save time (and assumedly cost).
47:40 - We get a quick glance of the team of people who are walking around behind the scenes with Destin and Tory. Admittedly, it looks like Tory is taking Destin around solo, but there are clearly people supervising even the CEO the whole time.
In general, I'm incredibly impressed with Bruno's knowledge of the entire process. It's amazing to see that from a CEO. Maybe that's the way that all CEOs are, but I doubt it.
And, if you want even more, there's a second video - on Destin's second channel - where the guys get into some discussion about the rocket engines themselves and ULA's position within the industry. It's less materials-focused, but it's worth watching.
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.
In the article (sadly behind a paywall but detailed at IFLScience) scientists recount the process of using x-ray fluoroscopy to determine the precise elemental composition of the dagger's blade without any harm to the blade itself.
The scientists were even able to determine the exact meteorite from which the dagger was forged nearly 700 years ago.
The microlattice weighs only about one tenth as much as carbon fiber, and is actually slightly lighter than air itself, said Bill Carter, the director of the Sensors and Materials Laboratory at HRL.
It will likely first be used on space rockets that Boeing plans to build in about five years, and it should make its way into commercial planes about five years after that, said Carter. He said the cost of manufacturing will have to come down a little more before it is economically feasible to use on cars.
