Re: [Starlink] some post Starship launch thoughts

[Eugene Chang <eugene.chang@alum.mit.edu>]

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I found this YouTube of a deluge system test.
It doesn’t look like it uses enough water to succeed.
My intuition is the mass of water needed is approximately equal to the rocket’s mass.
Maybe the system doesn’t have to fully absorb the momentum of the engine exhaust. Still, 70% would be a much greater mass than what the video shows.

Has anyone seen a rough calculation of what is needed from the deluge system?
Some elements
mass of water to absorb/dissipate the thermal energy
mass of water to absorb/dissipate the momentum of the rocket exhaust.
the rocket engine exhaust momentum is greater than the weight of the rocket.

Are there tricks that I don’t know about?

Gene
-----------------------------------
Eugene Chang
eugene.chang@alum.mit.edu
+1-781-799-0233 (in Honolulu)





> On Apr 25, 2023, at 12:31 PM, Bruce Perens <bruce@perens.com> wrote:
> 
> 
> 
> On Mon, Apr 24, 2023 at 7:20 PM David Lang via Starlink <starlink@lists.bufferbloat.net <mailto:starlink@lists.bufferbloat.net>> wrote:
> If they dig a pool under the Starship Launch Mount, it will fill with water
> (they are already having to pump water out of the hole the rocket dug), if they
> line it with concrete, water will seep through, and the concrete will try to
> float on the water.
> 
> The deluge system produces a mixture of water and air. That is necessary for the acoustic deadening effect.
> 
> Once upon a time, there was a thing called Orion, which was supposed to be a big heavy shield that would be propelled into space by setting off atomic bombs on one side of it. Lots and lots of bombs. At some point people thought they could make a shield good enough. What SpaceX puts in now is going to be the closest we have come to Orion, just upside down.


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