đŸ’Ÿ Archived View for dioskouroi.xyz â€ș thread â€ș 29432727 captured on 2021-12-03 at 14:04:38. Gemini links have been rewritten to link to archived content

View Raw

More Information

-=-=-=-=-=-=-

Scientists find a way to ‘catapult’ rockets into space like ‘slingshots’

Author: rustoo

Score: 10

Comments: 8

Date: 2021-12-03 17:39:30

Web Link

________________________________________________________________________________

BasilPH wrote at 2021-12-03 19:00:42:

Also doubting the civilian use, but in the previous discussion somebody commented[0] that the main purpose might be military:

For military applications on the other hand, it's close to perfect. You don't need orbital insertion, you can accelerate your payload silently without allowing for detection in the early phase of the attack, your projectile starts at essentially cruise speed and can only be detected by infrared emissions due to atmospheric heating for a few seconds until the launch ablative heatshields are ejected. It's a fantastic first strike weapon.

I don't know if this is a more likely application, but we should at least consider that we don't know the whole story, for better or worse. It might very well be a military startup that tries to give itself some SpaceX marketing-sheen.

[0]:

https://news.ycombinator.com/item?id=29209456

robbedpeter wrote at 2021-12-03 19:05:40:

There's some similarities with the supersonic trebuchet to these ideas, in terms of engineering.

Mach 33 is needed to escape orbit, so if you were going to launch a ball bearing into space, you'd need something at least 33 times more powerful than the rubber bands and 2x4 trebuchet.

https://youtu.be/gdXOS-B0Bus

It'd be interesting to run through those parameterizations with assumptions scaled to maximize a payload for reaching orbit using things like modern high strength steel and mechanical advantage and so on. It seems possible.

The amount of energy involved is terrifying - a space launch trebuchet would also be an anti-tank trebuchet.

SonicScrub wrote at 2021-12-03 18:30:25:

Pure vapourware nonsense designed to extract money from investors with all the right buzzwords. Good luck getting a chemical rocket second-stage to survive 1000+ lateral g's and the immense thermal challenges of flying Mach 5+ at sea-level conditions.

more_corn wrote at 2021-12-03 18:35:27:

There are about a dozen serious problems with this plan. What happens to the rest of your spin system when your payload releases? What about air resistance? If you’re spinning up in a vacuum what happens when your payload hits atmosphere at orbital velocity?

What are your neighbors going to think about living near complicated, delicate, high velocity things like this?

I also take issue with the notion that “scientists” are working on this. Engineers? Yes. Dreamers with a nifty idea? Yes.

Will it ever work? Maybe if what seem like insurmountable problems get solved. I’m not holding my breath though, and I don’t want to be within 10 miles or anywhere down range of the attempt.

curiousfab wrote at 2021-12-03 18:13:44:

If it sounds too good to be true, it usually is.

Spinlaunch: BUSTED!:

https://www.youtube.com/watch?v=9ziGI0i9VbE

Spinlaunch: BUSTED (Part 2):

https://www.youtube.com/watch?v=ibSJ_yy96iE

Robotbeat wrote at 2021-12-03 18:30:58:

Man, I have my opinions on Spinlaunch, too, but I find thunderf*t’s videos (especially the BUSTED ones) unenlightening & unhelpful to rationally discussing the pros and cons of some technology.

Scott Manley’s video (if video is the format you prefer) on Spinlaunch was much better. Scott Manley also has a much better understanding of rockets and space technology than thunderf*t.

https://youtu.be/JAczd3mt3X0

cjensen wrote at 2021-12-03 18:59:04:

The tumbling in this video is a good demonstration of the angular momentum problem. The projectile has a carp ton of angular momentum after release, and there's no system in place to fix that. Maybe you could cancel it using the atmo and aerodynamics except that would probably melt the fins.

And angular momentum is just one of the challenges that appear to be unsolvable. When you hit orbital height, your velocity is in the wrong direction. How do you add enough horizontal velocity? How do you construct a rocket engine that can survive the forces involved in initial launch? How do you prevent the bearings from melting? How do you construct a launch chamber which survives the explosive compression when the projectile penetrates the vacuum barrier into the atmo?

And all with a Theranos-level of founder knowledge.

ortusdux wrote at 2021-12-03 18:48:53:

Previous discussion:

https://news.ycombinator.com/item?id=29198589