Hackaday Links: April 23, 2023

Hackaday Links Column Banner

Mark it on your calendars, folks — this is the week that the term RUD has entered the public lexicon. Sure, most of our community already knows the acronym for “rapid unscheduled disassembly,” and realizes its tongue-in-cheek nature. But given that the term has been used by Elon Musk and others to describe the ignominious end of the recent Starship test flight, it seems like RUD will catch on in the popular press. But while everyone’s attention was focused on the spectacular results of manually activating Starship’s flight termination system to end its by-then uncontrolled flight at a mere 39 km, perhaps the more interesting results of the launch were being seen in and around the launch pad on Boca Chica. That’s where a couple of hundred tons of pulverized reinforced concrete rained down, turned to slag and dust by the 33 Raptor engines on the booster. A hapless Dodge Caravan seemed to catch the worst of the collateral damage, but the real wrath of those engines was focused on the Orbital Launch Mount, which now has a huge crater under it.

So how close to space did Starship actually make it? Not even close, if your standard is the 100-km Kármán Line. If you want to visualize just how far that’s not, check out this fun little Space Elevator page. You start at ground level on Earth and scroll ever upward, with the different layers of the atmosphere being called out along with the altitudes of various aircraft and spacecraft — and meatcraft too, like Felix “Free Fallin'” Baumgartner’s famous sound barrier-breaking skydive, or the ridiculous bar-headed goose, which routinely flies in the rarified air above the Himalaya mountains honking loudly the whole time. This a space elevator, elevator music is kindly provided, although we were disappointed that it wasn’t “The Girl from Ipanema.”

A little closer to the ground, we ran across a spectacular bit of footage that shows just how lightning rods work. Physicists in Brazil set up a high-speed camera and managed to catch an aerial lightning bolt in the act of seeking out a leader from the ground, or rather from the roof of a tall building. The leader was one of just many stretching up from various charge-concentrating points on the ground, and it wasn’t clear which one of the leaders was going to “win” the race to complete the circuit. Watching the aerial bolt seeking the path of least resistance is fascinating, and hats off to the researchers for capturing these images.

This week on the podcast we talked about using an analog oscilloscope in X-Y mode as a vector graphics display. That had us pining for an analog scope of our own to play with, and while we’ve got a Tektronix 475, it’s a bit disassembled at the moment. Until we get that back together again, we’ll settle for this online oscilloscope that lets you play with things like Lissajous patterns. The scope’s “tube” is very convincing, and you can control both the persistence and color of the phosphor. You can use the virtual signal generator to pipe different functions to each input, throw audio from your microphone into the signal, control the trigger and timebase, and generally do all the fun things an oscilloscope can do.


And finally, for your viewing pleasure this weekend, we present some crazy engineering from the 1960s. The LeTourneau TC-497 “Land Train” was an attempt by the US Army to go where no road had gone before, particularly in arctic conditions — think “Cold War.” Ironically, the last surviving bit of Land Train hardware now lives in the desert, at the Yuma Proving Grounds in Arizona. The TC-497, which as the lead car in the train acted sort of like a locomotive in a traditional train, has been lovingly restored to its 1960s glory — without the nuclear reactor that could have powered it — when crews lived and worked aboard her. It’s an amazing bit of engineering history that you should check out.

7 thoughts on “Hackaday Links: April 23, 2023

  1. I’m not going to say the starship launch was a huge success. (as I don’t know enough about it to qualify that)

    But they didn’t aim for space, they didn’t want to go do space, they aimed slightly below space in a best case.
    A more valid number to look at is that they reached a velocity of 2km/s, which is a bit short of the 7km/s you need to reach a stable orbit. However, that also paints a worse picture then reality, as the Tsiolkovsky rocket equation tells us that the first velocity is much “harder” (requires more fuel) then the last bit of velocity.

    1. And the goal isn’t stable orbit in LEO either. I’ve been saying for a while that if anybody thinks they are serious about getting to Mars with a live human payload and all the accoutrements this implies with that chemical rocket straight from sea level with no staging in orbit.. They are deluded. Not gonna happen. Zero percent likelihood. It’s a stunt or a jobs program.

        1. That’s quite a bit more practical, but at that point why would you use the same vehicle for interplanetary and launch? The specialization of each vehicle is vastly different. We can look at all the Mars mission proposals from the 1970s and see much more developed and pragmatic plans to get there.

  2. Following the Twitter link, I learned in a another tweet there was a possibility of aurora for North America. So, I stepped outside and watched “the show” for a few minutes. It has been years since I had seen one.

Leave a Reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.