[AR] Re: starship pad flame trench?
- From: "Jake Anderson" <dmarc-noreply@xxxxxxxxxxxxx> ("jake")
- To: arocket@xxxxxxxxxxxxx
- Date: Fri, 21 Apr 2023 15:24:38 +1000
On 21/04/2023 8:47 am, Keith and Mary Stormo wrote:
There is very little distance from the surface to the water table.
That makes a trench unlikely. It is likely that they will have some
type of above ground diverter system. They seem to have some parts and
components for a diverter on site to install after this flight.
Keith
At 02:00 PM 4/20/2023, you wrote:
I continue to be baffled- Why not a flame trench or two?
The amount of energy- thermal, radiative, acoustical and inertial-
that is forced to bounce back and forth between the 33 motor array
must be staggering.
Even the latest refractory concrete, it seems, cannot survive. How
can the motors?
I think that is a lot of undue stress applied to those raptor IIs
that are already trying as hard as they can to melt and rip
themselves apart.
I guess there must be a reason, but I can't figure it out.
It's also hard to imagine that NASA at Kennedy in florida is going to
tolerate all the flying junk that seems to result from such powerful
launches, even if the ships them selves are super-reliable.
I want to see a "reverse aerospike" as the diverter.
OK so it's just a plain spike, with a water outlet at the top, dump a
squillion tonnes of water out the top of an 8ish meter high spike (to
fit under the OLM) that has a nice radiused curve into being level with
the ground.
Wouldn't catch all the engine plumes before they hit but it'd at least
let you give them an idea about which way to be heading and hopefully
allow the water layer to become film cooling for the pad. If you can put
the tip of the spike up far enough that the plumes from the centre
engines don't hit it at ignition even better.
Probably also replace the concrete pad directly under the ring with a
nice bit of full thickness welded 6" plate steel. You might erode it
some but if there's no edges you won't get under it to do that lifting
and excavation that happened.
For the surrounding concrete make it like a spillway, they have
interlocking joints that are angled to prevent high speed water getting
under an edge. Seals to prevent water pressure pushing into a joint and
vents so that if water does get behind a block it's able to drain before
building pressure.
The concrete just outside the ring that wasn't *lifted* seemed to
survive fairly intact so it doesn't look like they are actually far from
having a working solution, just with this much energy even a small
problem (concrete cracking and letting pressure build behind it) leads
to dramatic outcomes.
That said, I'd bet a coke that at least some of the problems they had
were due to acoustic bashing on engine components. That spin manoeuvrer
is going to be really sensitive to residual thrust. One valve not
closing allowing methane to vent through an engine would probably
explain the ongoing burn after the MECO call and the inability to separate.
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