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Starship / Super Heavy

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Re: Starship / Super Heavy

#231

Post by CGZp9X9k »

ateng wrote: post #102
SECProto wrote: post #97

Earlier quoted context omitted.

Reorienting requires the use of main engines. You want to relight them only once, to ensure that the header tanks and the "downcomer" remain full. Additionally you want to burn off as much speed as possible with the bellyflop, so flipping vertical as late as possible. All combined this means combining the landing burn with the flip is best, as close to landing as possible.

It has a cute nickname, “Suicide Burn”. Why is it efficient? [ https://www.reddit.com/r/KerbalSpaceProgram/comments/2z534g/... ]

Guessing we won't be using constant altitude landings in real life?

Re: Starship / Super Heavy

#232

Post by itsoktocry »

Denvercoder9 wrote: post #227
peter303 wrote: post #178

SpaceX should locate next to Blue Origin in Texas.

Why? Their Texas facility is hundreds of miles inland, not exactly a location you'd want to launch enormous, experimental rockets that tend to explode from. Also, Blue Origin is just an expensive hobby compared to SpaceX. They're older, but have never flown anything to orbit, compared to the 100+ missions SpaceX has performed.

>Also, Blue Origin is just an expensive hobby compared to SpaceX.

Who cares? They are building interesting stuff too. We are in an amazing time for Space tech.

Why do Musk fans talk of "supporting the mission" out of one side of their mouth, and denigrate the competition every chance they get out of the other? It happens with Tesla and EVs too. Toxic communities.

Re: Starship / Super Heavy

#233

Post by qayxc »

baq wrote: post #207
maccam94 wrote: post #127

Earlier quoted context omitted.

Note that the $2M is to launch a fully loaded (100 tons of payload) Starship into low earth orbit (LEO). Launching it further, such as to the Moon or Mars, requires refueling while in-orbit. I've seen estimates from Musk that it would take 6-7 launches of a tanker variant of Starship to deliver enough fuel to fill an empty Starship (it could be stockpiled in an orbital depot ahead of the main payload launch). So the…

ask any astronomer what they could do with extra $150M per launch and watch them salivate. also, this thing could lift JWST pretty much without that complex unfolding mechanism. genuinely exciting.

The mirror of JWST is too wide - you'd still need the complex folding mechanism. edit: it's actually the mirror plus the sub shield that's too wide - the mirror by itself would even fit into an Ariane 5 fairing.

Re: Starship / Super Heavy

#234

Post by awestroke »

itsoktocry wrote: post #232
Denvercoder9 wrote: post #227

Earlier quoted context omitted.

Why? Their Texas facility is hundreds of miles inland, not exactly a location you'd want to launch enormous, experimental rockets that tend to explode from. Also, Blue Origin is just an expensive hobby compared to SpaceX. They're older, but have never flown anything to orbit, compared to the 100+ missions SpaceX has performed.

> Also, Blue Origin is just an expensive hobby compared to SpaceX. Who cares? They are building interesting stuff too. We are in an amazing time for Space tech. Why do Musk fans talk of "supporting the mission" out of one side of their mouth, and denigrate the competition every chance they get out of the other? It happens with Tesla and EVs too. Toxic communities.

Because Blue Origin is a toxic company. They tried to patent landing on a barge at sea even though SpaceX had already done it. They have also never flown anything to orbit, yet try to bid on orbital missions

Re: Starship / Super Heavy

#235

Post by garmaine »

neuromanser wrote: post #124
garmaine wrote: post #96

Earlier quoted context omitted.

Probably because most of the world has a different definition.

1 : an invented fact believed to be true because it appears in print 2 : a briefly stated and usually trivial fact https://www.merriam-webster.com/dictionary/factoid

Note that these are OPPOSITES.

Re: Starship / Super Heavy

#236

Post by Someone »

numpad0 wrote: post #230
m4rtink wrote: post #219

Earlier quoted context omitted.

IIRC this is the case when Soyuz LES activated on the pad before an unmanned test flight, killing some of the ground crew.

So not in flight. Not relevant. People gets hurt by airbags all the time trying to service them. That doesn’t tell if it’s worth having them in actual situations they’re designed for, nor whether the situations are worth preparing for.

It is relevant. If (giving an extreme example to make the point), statistically two humans were killed servicing airbags for every life saved by airbags, cars wouldn’t have airbags (with possible exceptions for cars of the super rich and super important such as the POTUS)

Also, an escape system adds weight to a rocket. That weight could be used for other stuff that makes the rest of the system more reliable (slightly stronger fuel tanks, redundant pumps, whatever). Designing the escape system also takes resources away that could be used to improve the safety of the primary system.

For rockets, it’s not easy to decide what’s the best choice; we launch too few of them, and the ones we launch change too often to gather reliable statistics. Getting real-world data on the reliability of escape systems definitely is hard, as it requires numerous rocket failures or elaborate test setups (a full test must include high speed and an explosion that may throw material through the engine of the escape capsule)

Re: Starship / Super Heavy

#237

Post by throwaway316943 »

simonh wrote: post #154
randallsquared wrote: post #132

Earlier quoted context omitted.

I believe it requires a refuel in orbit to get to the moon. So, two missions, but still super impressive.

More than that actually, it takes I think 3 tankers to fully top up a Starship in orbit, and the Lunar model needs to go into an elliptical orbit towards the moon and have at least one more top up again before having enough fuel for the rest of the mission.

I thought the full refuel was only necessary for a Mars mission?

Re: Starship / Super Heavy

#238

Post by z3t4 »

iso947 wrote: post #186
beaner wrote: post #168

Earlier quoted context omitted.

Genuine question, how will tankers get into space? If most of the ship's size is already dedicated to fuel that's burnt, that seems to leave little left for fuel payload. I also assume fuel payload would be much heavier than other types of payload, requiring more ship fuel to launch it, further taking up space. It seems like for every full refill you could provide in space it'd take an additional 3-4 ships just to ge…

About that yes, but remember that a fully loaded starship in orbit can land on any solid surface in the solar system and return to earth (except for Venus) Starship’s usable volume is over 100 times that of an Apollo lunar lander.

You could also add 3-4 extra stages and put an even bigger tanker into space. But I guess there will be diminishing returns due to the crushing weight. It would probably be cheaper to make many smaller unmanned vessels and boost them via an electromagnetic rail, then assemble it in orbit.

Re: Starship / Super Heavy

#239

Post by maccam94 »

ggreer wrote: post #149
wongarsu wrote: post #51

Earlier quoted context omitted.

Yes. Without it large rockets like the space shuttle might create more than 200db at lift off, enough to kill someone or to damage the rocket https://en.wikipedia.org/wiki/Sound_suppression_system

If rocket damage is a concern, why don’t such rockets destroy themselves right after leaving the launchpad? At that point the water suppression is no longer relevant but the sound waves are just as powerful. It can’t just be that the ground reflects sound waves, since that would only be a ≈3dB (2x) increase in sound energy. Rockets with >2x more thrust seem to use the same sound suppression, so rocket damage can’t be…

The issue is that the sound waves bounce off the pad back towards the rocket. Once the rocket has left the pad, the sound waves proceed behind it and there's no risk of them hitting the body.

Re: Starship / Super Heavy

#240

Post by MertsA »

avmich wrote: post #63
gibolt wrote: post #40

Earlier quoted context omitted.

It is approximately a 30 storey building. The majority of it is filled with extremely dense liquid fuel. The ability to lift that into orbit (minus most fuel and booster) with both halves still able to land is an insane feat.

You mean, extremely cold. Not particularly dense, methane is about half of water density, oxygen is about 10% more.

Presumably they mean compared to hydrolox like Delta IV or the Space Shuttle.
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