- #106
Rive
Science Advisor
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Just for the log: Falcon Heavy has 27 engines.artis said:starship seems to me to be the second only attempt in history to make a functioning rocket out of so many parallel engines
Just for the log: Falcon Heavy has 27 engines.artis said:starship seems to me to be the second only attempt in history to make a functioning rocket out of so many parallel engines
Ok I missed that , haven't followed that closely to latest advancements in rocket engineering.Rive said:Just for the log: Falcon Heavy has 27 engines.
They intend to use a steel water jacketed plate to dissipate the heat. The engines generate over 90 GW of heat. I would suppose you don't want to generate steam in the jacket. Steel is a poor conductor of heat. This plate is about 10m in diameter. Even if say 10% of the heat is transferred to the jacket you need to absorb 9GW for about 3 seconds. The water in the plate will be in there for several seconds at least for a surface temperature of several thousand degrees C. If bubbles form at the surface of the plate will the plate buckle or melt?artis said:Don't wish to sound like mr. Wise guy or mr. "told ya so" but rockets with far less thrust and less engine exhaust require water spray jets to save the launchpad so that it can be reused without repairs. NASA knows this, everyone knows this, it's been practically tested.
I don't like the apparent shoot-from-the-hip approach either, but presumably NASA did review and approve the pad design/construction prior to launch.artis said:Don't wish to sound like mr. Wise guy or mr. "told ya so" but rockets with far less thrust and less engine exhaust require water spray jets to save the launchpad so that it can be reused without repairs. NASA knows this, everyone knows this, it's been practically tested.
How in the world anyone at SpaceX thought that this rocket would not absolutely obliterate everything below it especially without a waterjet or whatever flame retarder , I just don't get it.
I would understand the wish to rush forward without delays and then repair whatever damage comes afterward but thinking such a launch wouldn't cause serious damage is simply not imaginable.
I'd been under the impression that the water deluge was more/exclusively for sound abatement. Maybe they calculated they didn't need it.gleem said:Musk always talks about using the simplest solution with minimum parts. A water deluge/flame trench system seems like the best KISS solution.
And then there is no sound abatement.
russ_watters said:Maybe they calculated they didn't need it.
By "sound" I thought we really meant "vibration". Harmful to the spacecraft.gleem said:With no noise abatement and twice the power, the noise levels will be higher....
Do you think they would do it for a few birds and turtles?
I got 120 MHp from somewhere on the web for the total HP of the Starship which I can't remember and converted it to watts. However, I can show a direct calculation using space X fuel consumption of 194kg/sec/engine which gives a higher heat output.artis said:@gleem I did not know that the total heat output of those engines was 90GW, but i can't find any reference for that either , can you please post some?
from https://en.wikipedia.org/wiki/Sound_suppression_systemartis said:From what I understand the waterjet is there not so much for sound dampening but for the rapid cooling of the exhaust flame/gas so that it doesn't behave like a welding plasma torch vaporizing and cutting everything in it's path.
Sites for launching large rockets are often equipped with a sound suppression system to absorb or deflect acoustic energy generated during a rocket launch. As engine exhaust gasses exceed the speed of sound, they collide with the ambient air and shockwaves are created, with noise levels approaching 200 db.
That is the biggest concern I am sure but 145 dB at two miles with a water deluge is very "loud" and the Starship test broke windows in Port Isabel 6 miles away.russ_watters said:By "sound" I thought we really meant "vibration". Harmful to the spacecraft.
SpaceX has taken risks with test articles frequently - often it works (despite "everyone" claiming it cannot work in advance) and ends up being a great solution. In the rare cases where it doesn't work everyone has to shout how SpaceX is stupid, of course.artis said:How in the world anyone at SpaceX thought that this rocket would not absolutely obliterate everything below it especially without a waterjet or whatever flame retarder , I just don't get it.
We have pictures of the steel plate they are building. The components were already spotted before the Starship test launch.artis said:Either way Elon's remarks about a "steel plate" do sound somewhat humorous.
So often that I can't help to suspect that they are cutting cost on disassembly and disposal this waymfb said:SpaceX has taken risks with test articles frequently
I'm not saying their stupid, and am not among those that enjoy seeing others fail, anyone who tries hard enough long enough, eventually succeeds or at least gets valuable experience.mfb said:SpaceX has taken risks with test articles frequently - often it works (despite "everyone" claiming it cannot work in advance) and ends up being a great solution. In the rare cases where it doesn't work everyone has to shout how SpaceX is stupid, of course.
Are you implying that their allowing stuff to blow up on purpose so that no one has to unscrew the bolts and dispose of the materials afterwards?Rive said:So often that I can't help to suspect that they are cutting cost on disassembly and disposal this way
I'm just ... thinking that while proper disposal of a no longer useful proto of this size is a royal pain in ***, as an alternative they may have considered the ... entertainment value of the thing parallel with the inevitably limited gains from one such test ...artis said:Are you implying
Are you sure?artis said:I'm not saying their stupid
SpaceX did the calculations and estimated that the launch pad would survive. You claim you could have known otherwise before the launch. Without even doing a calculation yourself!artis said:What I am saying though is with a rocket like this even without calculation one can be sure there will de destruction of the launch site without proper retarders, absorbers, jets, flame tunnels etc.
According to SpaceX statements made after the launch attempt, they knew they had to change it and were preparing to do so. They calculated that what they had would be good for one launch.russ_watters said:I'd been under the impression that the water deluge was more/exclusively for sound abatement. Maybe they calculated they didn't need it.
That poor bird theregleem said:Well the OLM water deluge system has be completed and tested.