[ExI] Rocket lander control systems

[spike at rainier66.com]

-----Original Message-----
From: extropy-chat <extropy-chat-bounces at lists.extropy.org> On Behalf Of
BillK via extropy-chat
Sent: Sunday, January 3, 2021 4:54 PM
To: ExI chat list <extropy-chat at lists.extropy.org>
Cc: BillK <pharos at gmail.com>
Subject: Re: [ExI] Rocket lander control systems

On Sun, 3 Jan 2021 at 22:02, spike jones via extropy-chat
<extropy-chat at lists.extropy.org> wrote:
>
> Imagine four sturdy towers with a mesh net made of nylon cord of about 3
cm diameter with cord centers at about 30 cm.  The cords are attached at
every intersection by something flimsy that will break, such as zip ties,
just strong enough to hold the cords in place in a mesh configuration.
>
<snip catch it in a net>
>
> spike
> _______________________________________________


It's called the Super Heavy Booster because it is *heavy*.  :) I think the
dry weight of Stage 1 is about 300 metric tons.
Gotta get a really big strong net!


BillK

_______________________________________________


Ja, but it comes down empty.

We can do some ballpark figures in our heads.  Imagine a first stage, 4
meters diameter, length 30 meters.  Agreed those dimensions would be
suitable to support the upper stages during a 2 g launch event?

OK, Lox is about the same density as water, a little higher, kerosene is
lower than water, but you need less of it, so we can just use water density
for BOTEC estimate.  Those dimensions return a fuel/oxidizer mass of about
400 tons.  A typical Lox/JP4 first stage has a ratio of about 1/11 range, so
lets go with the heavy end, about 40 tons, which is about the mass of an
empty Boeing 737.  

A single strand of that 3 cm diameter nylon cord is good for 15 tons.  Get
several of them working together, they should be able to deal with the
momentum of our 737 eqivalent.  If we can slow it down enough before impact
with the net, we aughta be able to catch and suspend something of that mass.

spike