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boundary="Apple-Mail=_B5F16C05-16BF-434E-B658-6BBFE5C38EA6"; protocol="application/pgp-signature"; micalg=pgp-sha256 MIME-Version: 1.0 X-OriginatorOrg: alum.mit.edu X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: CO6PR12MB5427.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: d8c367b8-7566-4a3d-e4b7-08db45e168c6 X-MS-Exchange-CrossTenant-originalarrivaltime: 25 Apr 2023 23:04:23.0274 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 3326b102-c043-408b-a990-b89e477d582f X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: RivH8q/bVNKrIGWL7Pp6S832PsQ3tb/n5VR1YzMR1DofRA5YUf3277BrgmuVSPzVZ6OAFERprDcGrnKsJ7ctCFydIJNg3PYxtucWQXgc/a8= X-MS-Exchange-Transport-CrossTenantHeadersStamped: LV2PR12MB5725 Subject: Re: [Starlink] some post Starship launch thoughts X-BeenThere: starlink@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: "Starlink has bufferbloat. Bad." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 25 Apr 2023 23:04:25 -0000 --Apple-Mail=_B5F16C05-16BF-434E-B658-6BBFE5C38EA6 Content-Type: multipart/alternative; boundary="Apple-Mail=_C2E46162-9698-4F70-8E8C-F34297AF72EC" --Apple-Mail=_C2E46162-9698-4F70-8E8C-F34297AF72EC Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 I found this YouTube of a deluge system test. It doesn=E2=80=99t look like it uses enough water to succeed. My intuition is the mass of water needed is approximately equal to the = rocket=E2=80=99s mass. Maybe the system doesn=E2=80=99t 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=E2=80=99t 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 wrote: >=20 >=20 >=20 > On Mon, Apr 24, 2023 at 7:20=E2=80=AFPM David Lang via Starlink = > = 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. >=20 > The deluge system produces a mixture of water and air. That is = necessary for the acoustic deadening effect. >=20 > 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. --Apple-Mail=_C2E46162-9698-4F70-8E8C-F34297AF72EC Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=utf-8 I = found this YouTube of a deluge system test.
It doesn=E2=80=99= t look like it uses enough water to succeed.
My = intuition is the mass of water needed is approximately equal to the = rocket=E2=80=99s mass. 
Maybe the system = doesn=E2=80=99t 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=E2=80=99t 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=E2=80=AFPM = David Lang via Starlink <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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