Author Topic: Starship/Booster Propellant Questions  (Read 8038 times)

Online meekGee

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Re: Starship/Booster Propellant Questions
« Reply #20 on: 11/21/2023 05:37 am »
Senior Sanman you are going the wrong way!
ABCD - Always Be Counting Down

Offline matthewkantar

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Re: Starship/Booster Propellant Questions
« Reply #21 on: 11/21/2023 01:59 pm »
Where is the member with the tag line about solid rockets being a branch of fireworks?
« Last Edit: 11/21/2023 03:06 pm by matthewkantar »

Offline Jim

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Re: Starship/Booster Propellant Questions
« Reply #22 on: 11/21/2023 03:07 pm »
Methane's freezing point is -182 C (exactly the same as LOX temperature, and well above LH2 temperature) so is there any chance of using solid methane as a fuel? You'd then heat/melt portions of it to flow it into the engines. This might require that the fuel tank be compartmentalized into smaller cells/slices, each of which could be heated/thawed as required. This would limit the amount of slosh, fluid hammer, avoid ullage effects, etc.

LOX freezing point is -219 C, which is still above LH2 temperatures.
No, too complex.    Slosh is not a problem.  If it is, there are easy fixes.

Offline JamesH65

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Re: Starship/Booster Propellant Questions
« Reply #23 on: 11/21/2023 03:13 pm »
You cannot turn a solid off or throttle it. Just that would make it a non-worker.

Offline sanman

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Re: Starship/Booster Propellant Questions
« Reply #24 on: 11/21/2023 03:18 pm »
Senior Sanman you are going the wrong way!

I'm not going - I'm simply asking  :)

Offline Slarty1080

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Re: Starship/Booster Propellant Questions
« Reply #25 on: 11/21/2023 04:08 pm »
would take 1000 ton cranes or more
Lets work out a number for that...

if stage 2 is 1200t methalox + 120t dry + 0t payload = 1320t
assume for now stage 1 without fuel is still 200t
best-case ISP seems to be 304s (I'm surprised, I thought it would be far lower than that)
ignore gravity drag for now and just accelerate the stack to 1800 m/s
I get 1260t of solid fuel, so 1460t on the gantry cranes, SPMTs and chopsticks.

What impact would it have on exclusion zones? I often hear how SH is not "a nuke" because the meth and lox are not well mixed
Superheavy holds around 2800 or more tonnes of propellants to do what it does, and solid propellants have a lower Isp than good liquid propellants so it seems unlikely that 1260 tonnes of solid propellant would be anywhere near enough. That should put an end to it.

But additionally parachutes don't scale well and immersion in salt water is not beneficial to say the least nor good for rapid reuse. Solid rockets also produce a lot more noxious gases when burnt and could present a contamination problems if there was any serious incident on the pad (eg ammonium perchlorate and wildlife don't mix). Check out an Ariane launch years ago that detonated a few miles up and scattered burning solid propellant chunks all of the place.

But beyond all that I can hear Mr Musk... and how much did you say these solid booster propellants cost compared to Methalox? Whilst his engineers shuffle uncomfortably in the background.
My optimistic hope is that it will become cool to really think about things... rather than just doing reactive bullsh*t based on no knowledge (Brian Cox)

Offline matthewkantar

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Re: Starship/Booster Propellant Questions
« Reply #26 on: 11/21/2023 10:10 pm »
From Wikipedia, on a big solid rocket projectl from the 1960’s:

“The largest solid rocket motors ever built were Aerojet's three 6.60-meter (260 in) monolithic solid motors cast in Florida. Motors 260 SL-1 and SL-2 were 6.63 meters (261 in) in diameter, 24.59 meters (80 ft 8 in) long, weighed 842,900 kilograms (1,858,300 lb), and had a maximum thrust of 16 MN (3,500,000 lbf).”
 
They had to dig a canal to move them. The final motor they tested is still in the hole they dug for it. The project was an uneconomic dead end.

Starship Booster will have around 90 MN of thrust at lift off, more than five times the 260, so a solid first stage would need to weigh ten million kg?

Offline Brigantine

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Re: Starship/Booster Propellant Questions
« Reply #27 on: 11/21/2023 10:30 pm »
ten million kg?
10 kilotons at Boca Chica

83m wide crater, 440m wide fireball, dry wood within 710m catches fire (dry wood in a wetland?), 5.8km high mushroom cloud, but the village survives
« Last Edit: 11/21/2023 10:37 pm by Brigantine »

Offline edzieba

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Re: Starship/Booster Propellant Questions
« Reply #28 on: 11/22/2023 10:41 am »
And the solid grains collapse under their own weight and fall out the nozzle to produce a very explosive but unhelpfully not propulsive pile of rubbery scraps.

No capes solids!

Offline Twark_Main

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Re: Starship/Booster Propellant Questions
« Reply #29 on: 11/22/2023 10:59 am »
So is a liquid-fueled booster worth it? What if SH had been a giant SRB instead?

...

Incoming tweet:

"Super Heavy is being redesigned again. Delightfully counterintuitive!!"
« Last Edit: 11/22/2023 11:00 am by Twark_Main »
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Offline launchwatcher

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Re: Starship/Booster Propellant Questions
« Reply #30 on: 11/22/2023 02:25 pm »
From Wikipedia, on a big solid rocket projectl from the 1960’s:

“The largest solid rocket motors ever built were Aerojet's three 6.60-meter (260 in) monolithic solid motors cast in Florida. Motors 260 SL-1 and SL-2 were 6.63 meters (261 in) in diameter, 24.59 meters (80 ft 8 in) long, weighed 842,900 kilograms (1,858,300 lb), and had a maximum thrust of 16 MN (3,500,000 lbf).”
 
They had to dig a canal to move them. The final motor they tested is still in the hole they dug for it. The project was an uneconomic dead end.

Starship Booster will have around 90 MN of thrust at lift off, more than five times the 260, so a solid first stage would need to weigh ten million kg?
There was a design study which looked at strapping four of those to a stretched Saturn V:

Quote
American orbital launch vehicle. Boeing study, 1967-1968. Use of full length 260 inch solid rocket boosters with stretched Saturn IC stages presented problems, since the top of the motors came about half way up the liquid oxygen tank of the stage, making transmission of loads from the motors to the core vehicle complex and adding a great deal of weight to the S-IC. Boeing's solution was to retain the standard length Saturn IC, with the 260 inch motors ending half way up the S-IC/S-II interstage, but to provide additional propellant for the S-IC by putting propellant tanks above the 260 inch boosters. These would be drained first and jettisoned with the boosters. This added to the plumbing complexity but solved the loads problem.
http://www.astronautix.com/s/saturnv4-260.html


Offline Stan-1967

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Re: Starship/Booster Propellant Questions
« Reply #31 on: 11/22/2023 03:28 pm »

There was a design study which looked at strapping four of those to a stretched Saturn V:

Quote
American orbital launch vehicle. Boeing study, 1967-1968. Use of full length 260 inch solid rocket boosters with stretched Saturn IC stages presented problems, since the top of the motors came about half way up the liquid oxygen tank of the stage, making transmission of loads from the motors to the core vehicle complex and adding a great deal of weight to the S-IC. Boeing's solution was to retain the standard length Saturn IC, with the 260 inch motors ending half way up the S-IC/S-II interstage, but to provide additional propellant for the S-IC by putting propellant tanks above the 260 inch boosters. These would be drained first and jettisoned with the boosters. This added to the plumbing complexity but solved the loads problem.
http://www.astronautix.com/s/saturnv4-260.html

It is so hard to have a good new idea, and now I read that section from astronautix and realize how hard it is to have new bad ideas as well.

I was trying to think of a more bad idea than a +9m SRB to replace SH, then I had thoughts of encasing SH with off the shelf SLS style SRB's with +2cm thick steel casing ( pipe bombs) wrapped around the SH core.  That would take a stunning 1.6M to 2M lbs of steel casings falling back to earth. Turn SS/SH into a 2.5 stage beast like a Vulcan or A6 sustainer core configuration. 

I can think of only one company that would love this idea, &  I hope Mike Griffin never reads this thread.

And in my head I am singing Pink Floyd's "Two Suns in the Sunset"  thinking of the explosion that it would make.

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