[Starlink] some post Starship launch thoughts

[David Lang]

On Tue, 25 Apr 2023, David P. Reed via Starlink wrote:

> Ideally, the initial acceleration of a rocket would be better imparted by an external launcher (at least on the Earth - not initially on Mars). For example, an electromagnetic linear accelerator that contains the rocket while it accelerates. (We're not talking a sub-launched missile or a carrier-launched airplane here, and even on carriers, electromagnetic catapults have been developed that work better than steam ones - despite Trump's Musk-like idiotic statement that "steam is the best way" for carriers).
> 
> The reusability of an electromagnetic launcher is clearly far better than for the "reusable" launch stage that holds the equivalent energy in fuel form. (snark: and Musk is a genius who "invented" a whole system for using tubes and magnets called Hyperloop).
> 
> It doesn't need to be a tube, it could be a "rail" (railguns work, and are cool in SF, too).
> Powering it just needs a way to store and release electrical energy fast - a battery, basically, which can be wired up as a collection of storage cells in parallel.
> 
> And this wouldn't pollute the atmosphere anywhere near as much, I'd guess.

also not a rocket engineer, but I've been paying attention for a while

are you aware of spinlaunch? they are trying to get their initial velocity with 
electricity, via spinning the rocket at the end of an arm rather than a linear 
accelerator.

re: linear accelerator

1. you want to gain alititude quickly to get out of the thickest air, that takes 
a launch up the side of a mountain, not something horizontal.

2. having your velocity really high as you leave the launch facility (as opposed 
to as you gain speed at higher altitudes) will significantly increase your 
aerodynamic forces

3. good mountains don't tend to have ocean to the east for problems to fall 
into, even on islands you tend to have population pretty close

4. this is a LOT of mass to move, yes, the more you can power with the linear 
accelerator, the less you need in the rocket, but you still need to move a LOT 
of mass.

5. rockets aren't stressed to be on their side (at least not when fully 
assembled and fueled), adding structure to support this will reduce your gains

6. you will need to mount the rocket to a sled, there's not a lot of ferris 
metal in a rocket for magnets to grab

7. there are a lot of delicate electronics on a rocket, how will they handle the 
very strong magnetic fields (even if you have them focused on a sled, they will 
need to be strong enough that they could be a risk even further away


all these things said, I would love to see someone try it. I think that an 
accelerator up the side of a mountain could do wonders for unmanned cargo. 
Possibly not electronics, but a lot of structure, and more importantly fuel, 
could be launched this way.

But until we have a much more substantial presense in space, I don't see it 
worth anyone investing the money to make it work. The F9 reusability was 
criticised as being unneded, the Starship is being criticised as being unneeded. 
(both with the argument that there wasn't enough demand to need them). I expect 
demand to grow with capacity, and as the cost comes down, outstripping the 
capacity, but we have a ways to go.

David Lang
-------------- next part --------------
_______________________________________________
Starlink mailing list
Starlink at lists.bufferbloat.net
https://lists.bufferbloat.net/listinfo/starlink