Beer Keg Plumbing for a Liquid Rocket

When you think of a high performance liquid rocket, what do you think of? Beer kegs? No? Well, when [Ryan] from the YouTube channel “Project KegRocket” saw a beer keg, the first thing he and his friends saw was a pressurized rocket body.

You wouldn’t be crazy if the first thing you thought of was something designed by a massive company or university. Liquid rockets are far from simple to develop, with Keg Rocket being no exception. Liquid oxygen and alcohol is the oxidizer/fuel mixture of choice. Liquid oxygen in particular is a problem with its cryogenic temperatures and tendency to do what rocket fuel does best, burn. This problem causes a large amount of work to simply connect the pipes. Traditional O-rings have no chance at surviving, along with most other non-metallic solutions.

Even with all these problems, the group creating the piece of art is more than capable, having experience creating similar rockets in the past. As of currently, the pumping has been pressure and leak checked. We will be watching this project closely for updates and an eventual launch.

For more rocketry science, be sure to check out aerospike engines for the most efficient engines around. If you want efficiency in your pizzas and beer kegs, check out this keg pizza oven instead!

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Apprezzata review di #Metropolis di Lucia Tedesco; uno dei film preferiti di papà.

Metropolis non nasce dal nulla: Lang prende un filo già teso e lo trasforma in un cavo d’alta tensione. La macchina come centro (e padrone) dell’attività umana è un’ossessione che attraversa il cinema quasi fin dall’inizio, poi esplode dopo di lui.
Già nel cinema muto la macchina è ambigua: promessa di progresso e minaccia disumanizzante (profetico, vero?).

In "A Trip to the Moon” (1902, di Méliès) la macchina è ancora giocattolo e meraviglia. Razzi, ingranaggi, leve: la tecnologia è fantasia,è l’infanzia del mito tecnologico che tutti abbiamo sognato!

Lo straordinario corto "The Electric Hotel” (1908, di Segundo de Chomón) vede valigie che si disfano da sole, spazzole automatiche, letti meccanici. È una satira purissima dell’automazione. La macchina come servitore… che sfugge di mano (anche di questa tematica il cinema ne ha lodato l'imperfezione).

E poi c'è "Homunculus” (1916, grnuino Otto Rippert) che è poco conosciuto ma cruciale: un uomo artificiale, creato in laboratorio, "vive" alienato, incapace di empatia. Qui la macchina (o l’uomo-macchina) è già allo stadio di tragedia morale.

Il tema industriale torna anche in "Algol” (1920, di Hans Werckmeister) dove lo scenario è in pratica l'utopia dell'energia infinita, il potere industriale, alienazione (che torna ad essere tratto dominante del futuro immaginato). Anticipa Metropolis in modo sorprendente: il controllo delle masse passa attraverso il controllo della tecnologia.

Tutti questi film preparano il terreno, ma Lang fa il grande salto: la macchina non è più un oggetto narrativo, è l’architettura stessa della società. E dopo l'uscita, il cinema non torna più indietro. La macchina diventa sistema, ideologia, destino.

Da vedere assolutamente: "Modern Times” (1936, di Chaplin) che fornisce una risposta umanista alla catena di montaggio che divora l’uomo. Satira, sì, ma lucidissima dove l’essere umano viene ridotto a ingranaggio intercambiabile (un po' come in "Elysium").
Adorabile è "Things to Come” (1936, di William Menzies), tratto da H.G. Wells: la macchina come "possibile" salvezza tecnocratica. Un ottimismo quasi inquietante, con l’ordine meccanico contro il caos umano.
"2001: A Space Odyssey” (1968, capolavoro di Kubrick) segna il punto di non ritorno: HAL 9000 non è più una macchina che serve l'uomo: lo valuta (concetto ripreso in "Alien").
"THX 1138” (1971, di George Lucas) vede la macchina come sistema di controllo totale. Non solo hardware, ma burocrazia, farmaci, sorveglianza. Metropolis senza cattedrali, solo corridoi, insomma.
E poi "Blade Runner” (1982, di Ridley Scott).. Qui la domanda si ribalta: se la macchina prova emozioni, cos’è l’uomo? La centralità non è più la macchina industriale, ma quella ontologica. Il concetto viene poi ampliato, in un'ottica più introspettiva in "Blade Runner: 2049".
Con "The Matrix” (1999, dei fratelli - ora sorelle - Wachowski) è la perfetta chiusura del cerchio: l’uomo è letteralmente una batteria. La macchina non organizza il lavoro umano, lo coltiva per alimentarsi (concetto visto anche in "Soylent Green").
Lang, alla fine, non ha inventato il tema; paradossalmente ha fatto di peggio (o di meglio): lo ha reso inevitabile.

Polymer Skins That Change Color and Texture When Exposed to Water

Researchers at Stanford University recently came up with an interesting way (Phys.org summary) to create patterns and colors that emerge when a polymer is exposed to water. Although the paper itself is sadly paywalled with no preprint available, it’s fairly easily summarized and illustrated with details from the Supplementary Data section. The polymer used is poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), which when exposed to an electron beam (electron-beam lithography) undergoes certain changes that become apparent when said water is added.

The polymer is hygroscopic, but the electron beam modifies the extent to which a specific area swells up, thus making it possible to create patterns that depend on the amount of electron beam exposure. In order to ‘colorize’ the polymer, complex cavities are created that modify the angular distribution of light, as illustrated in the top image from the Supplemental Data docx file.

By varying the concentration of IPA versus water, the intermediate swelling states can be controlled. Although this sounds pretty advanced, if you look at the supplementary videos that are already sped up a lot, you can see that it is a very slow process. Compared to an octopus and kin whose ability to alter their own skin texture and coloring is legendary and directly controlled by their nervous system, this isn’t quite in the same ballpark yet, even if it’s pretty cool to watch.

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Lead Acid Battery Upgraded to Lithium Iron Phosphate

Lithium batteries have taken over as the primary battery chemistry from applications ranging from consumer electronics to electric vehicles and all kinds of other things in between. But the standard lithium ion battery has a few downsides, namely issues operating at temperature extremes. Lead acid solves some of these problems but has much lower energy density, and if you want to split the difference with your own battery you’ll need to build your own lithium iron phosphate (LiFePO4) pack.

[Well Done Tips] is building this specific type of battery because the lead acid battery in his electric ATV is on the decline. He’s using cylindrical cells that resemble an 18650 battery but are much larger. Beyond the size, though, many of the design principles from building 18650 battery packs are similar, with the exception that these have screw terminals so that bus bars can be easily attached and don’t require spot welding.

With the pack assembled using 3D printed parts, a battery management system is installed with the balance wires cleverly routed through the prints and attached to the bus bars. The only problem [Well Done Tips] had was not realizing that LiFePO4 batteries’ voltages settle a bit after being fully charged, which meant that he didn’t properly calculate the final voltage of his pack and had to add a cell, bringing his original 15S1P battery up to 16S1P and the correct 54V at full charge.

LiFePO4 has a few other upsides compared to lithium ion as well, including that it delivers almost full power until it’s at about 20% charge. It’s not quite as energy dense but compared to the lead-acid battery he was using is a huge improvement, and is one of the reasons we’ve seen them taking over various other EV conversions as well.

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