[ExI] Rocket lander control systems

[Rafal Smigrodzki]

On Sun, Jan 3, 2021 at 9:14 PM BillK via extropy-chat <
extropy-chat at lists.extropy.org> wrote:

> On Mon, 4 Jan 2021 at 02:07, spike jones via extropy-chat
> <extropy-chat at lists.extropy.org> wrote:
> >
> > Ja I misread the first post, my apologies.
> >
> > I don't think as big as Elon Musk does.
> >
> > Guess that's why he's rich and Im not.
> >
> > That notion of catching the first stage in a net is growing on me.  I can
> > see  something like that working out and possibly having some advantages
> > over a feet-first landing: your payload ratio might be better, even at
> the
> > expense of longer turn-around times.  Hard to say: it sounds like an
> > interesting portion of the envelope that hasn't been explored.
> >
> > I wouldn't be surprised if they were working on something like this back
> in
> > the 1950s and 60s when so much innovative rocket science was taking
> place,
> > but they didn't really have the control systems in those days which were
> up
> > to the task.  A human-controlled flight into a net is too risky and too
> slow
> > (humans can't react fast enough to control something that unforgiving.)
> I
> > think we could do this now however.
> >
> > spike
> > _______________________________________________
>
>
> As I understand it, he wants it to return like his earlier boosters,
> but to land back at the launch tower, standing on the base fins and
> using the launch tower arm to hold the rocket in position.
> So not really 'catching' it.
>
>
### He wrote about using the grid fins (not base fins) to catch the
booster. Big difference, since grid fins are needed anyway for descent from
orbit, so repurposing them for the additional application in landing would
be a pure gain in efficiency. He wrote "the best process is no process, the
best part is no part". It is indeed brilliant. Would do away with other
landing gear altogether and offload the landing gear complexity, such as
shock absorbers, and weight from the vehicle (where weight is a huge
penalty) to the landing tower (where weight does not matter). Again,
brilliant.

I remember SpaceX boasting that their grid fins are the largest single
piece titanium forgings ever, or something like that. Great thing, forged
titanium.

Rafal
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