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by ben_w 319 days ago
> I’m very skeptical about Spinlaunch, but even if you can pour enough epoxy over something to allow it to survive 10k Gs for a few minutes,

Please do watch the video I linked to — it was a surprise to the people whose cubesat design they lightly modified, that they didn't need to fill all voids with epoxy resin.

> I am not sure you can scale it to 100k+ Gs for weeks, for a postage stamp sized payload that has to be almost perfectly flat - that just seems like a completely different problem domain.

If anything, I expect "flat postage stamp" to be easier, even with a 100x increase in G-forces. Thin structure in compression -> total forces are still low. Balancing a fully laden lorry on a 10cm cube of steel (7.5kg vs 50 tons ~= 6,000x) seems borderline in the way that balancing a 10cm cube of steel on top of 1cm^2 of 80 gsm paper (=8mg vs 7.5kg ~= 937500) doesn't.

(Edit: forgot density of steel, thought it was 5 not 7.5)

> I think the idea bears further investigation, but the omission from the paper feels a bit odd.

100%. It does feel a bit like it's formalising my shower thoughts.

> Good luck with the novel!

Thanks, I'll need it! >_>
1 comments
EndsOfnversion 319 days ago
Ah, but that’s the thing it’s not compression it’s tension. Try hanging the same steel cube from the ceiling with a scrap of paper and things get decidedly more difficult.

And even if you can find some magic superglue left in the tube to hold it there, it has to hang there for weeks: A cubist sword of Damocles.

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ben_w 319 days ago
The tether is always in tension, in general the payload is allowed to be in either tension (if attached to the tether on the "top") or compression (if in a pouch of the same material as the tether, e.g. shepherd's sling configuration: https://en.wikipedia.org/wiki/Sling_(weapon)), at the preference of the system designer.
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EndsOfnversion 319 days ago
It’s a good point: I’d assumed that the plan was to make the payload of basically the same material as the tether/structure, and have it destructively tear-off at the right moment (maybe by having a watching supervisor structure lasering a weak point)

But I think pouching the payload (presumably forming the structure around the payload) just translates the problem into holding a 8kg steel block to the ceiling with 1cm square of paper formed into a harness, and expecting it to hold for weeks.

Either way - hopefully it will be addressed in a follow-up

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