totm nov 2023 SpaceX Discussion Thread

[Beccab]

6 hours ago, SpaceFace545 said:

Someone is saying this finally. If SS blows it's gonna leave an N1 size explosions, blah blah cryogenics are safer or something but it's still much larger than the N1. SS needs to be launched extremely far from everything. 

But it is wrong. It's not much larger than the N1, nor it is going to leave an N1 sized explosion. If it explodes it is going to be a fireball, not a nuke

[mikegarrison]

1 hour ago, Beccab said:

But it is wrong. It's not much larger than the N1, nor it is going to leave an N1 sized explosion. If it explodes it is going to be a fireball, not a nuke

Get enough LCH4 on one place and it can have a blast similar to a nuke.

Bottom line is that it takes a lot of energy to reach orbit, and that much energy can do a lot of damage if it is liberated in an uncontrolled manner.

A paper on the risks of LNG ships:

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwitq6uu_ZvzAhVPqZ4KHfoTCBAQFnoECBsQAQ&url=https%3A%2F%2Fwww.sciencedirect.com%2Fscience%2Farticle%2Fpii%2FS1877705812031359%2Fpdf%3Fmd5%3Deacac62c04afc755ef335ab35d9d78f3%26pid%3D1-s2.0-S1877705812031359-main.pdf&usg=AOvVaw0aYxxjso7O8yMHMwIrxMJg

Edited September 26, 2021 by mikegarrison

[funnelton]

7 hours ago, SpaceFace545 said:

Someone is saying this finally. If SS blows it's gonna leave an N1 size explosions, blah blah cryogenics are safer or something but it's still much larger than the N1. SS needs to be launched extremely far from everything. 

I seriously doubt that crew will ever fly on starship but if they do it definitely will need an abort to pull something away from ~350 feet of tanks holding volatile gases.

Don't forget, the launch tower is next to a nature reserve, if a superheavy blows up, it can have serious consequences for the environment and spaceX

Also, finally someone who thinks starship wont carry crew!

 

50 minutes ago, Beccab said:

But it is wrong. It's not much larger than the N1, nor it is going to leave an N1 sized explosion. If it explodes it is going to be a fireball, not a nuke

While starship isn't that taller than the n1, it has a lot more fuel, so much that the superheavy's fuel tanks can carry 3300 tons of methane and oxidizer, that weighs more than the N1 itself! (2750 tons)

Not to mention that the N1 explosion that destroyed its launchpad was caused by only 15% of its fuel and that still caused an explosion about 1kt

[Beccab]

4 minutes ago, funnelton said:

Don't forget, the launch tower is next to a nature reserve, if a superheavy blows up, it can have serious consequences for the environment and spaceX

That's what the FAA enviromental assestment is about, of which the draft expects no significant impacts in any category

5 minutes ago, funnelton said:

Also, finally someone who thinks starship wont carry crew!

There is little reason to think that

6 minutes ago, funnelton said:

Not to mention that the N1 explosion that destroyed its launchpad was caused by only 15% of its fuel and that still caused an explosion about 1kt

Which was again using RP-1. Superheavy uses methane, which is in no way comparable.

20 minutes ago, funnelton said:

While starship isn't that taller than the n1, it has a lot more fuel, so much that the superheavy's fuel tanks can carry 3300 tons of methane and oxidizer, that weighs more than the N1 itself! (2750 tons)

Of which 80% is liquid oxygen and 20% methane. The N1, instead, was almost 30% RP-1

[mikegarrison]

3 hours ago, Beccab said:

Which was again using RP-1. Superheavy uses methane, which is in no way comparable.

Only "in no way comparable" in the sense that methane is much easier to explode than kerosene is.

Both are hydrocarbon fuels, but liquid methane will obviously vaporize much easier, making it much easier to get a fuel/air explosion.

Edited September 26, 2021 by mikegarrison

[magnemoe]

5 hours ago, Beccab said:

But it is wrong. It's not much larger than the N1, nor it is going to leave an N1 sized explosion. If it explodes it is going to be a fireball, not a nuke

Its heavier than the N1, see no reason why it could not be an N1 sized blast, but you are correct its not an nuke or even something like the Beirut explosion with high explosives.
It will be an explosion, not an detonation at least for the most part, the relevant part here is how well methane is mixed with LOX and air then it burns and how much of the methane and LOX hitting the ground. 

[Hannu2]

1 hour ago, mikegarrison said:

Only "in no way comparable" in the sense that methane is much easier to explode than kerosene is.

Both are hydrocarbon fuels, but liquid methane will obviously vaporize much easier, making it much easier to get a fuel/air explosion.

Small amounts of methane can vaporize easier and form explosive mixtures with air. But I do not see significant difference in conditions of rocket explosion. Both are liquids which have to vaporize before chemical reactions. Temperature of methane is lower but heat of vaporization is larger. I think this kind of events are handled by orders of magnitude so explosion of Starship would be practically similar than explosion of N1.

I am sure that authorities have thought the possibility of explosion, it would not be the first rocket exploded on pad after all, and accepted SpaceX's safety measures (when they will give the permission for launch). Launch pad would be destroyed but very probably no one is injured and damage of others property is small. If worst case happens maybe they finish those oil rig launchpads before continuing tests.

[mikegarrison]

7 hours ago, Hannu2 said:

I think this kind of events are handled by orders of magnitude so explosion of Starship would be practically similar than explosion of N1.

I agree. That was overall my point.

[Damien_The_Unbeliever]

The idea that the SpaceX engineers wouldn't be building off of the decades of experience since  N1, in ignorance of N1, and not have any idea of how to protect their systems...

Thank goodness a random Internet commenter is here (a random game forum) to set them right.

Are you viewing the site as it will be used during any static fire attempts or launches? NO. We know the site is in flux. We know they at least know how to build berms, and are aware of flame trenches, etc.  They've also expressed (via Elon's interview with Tim Dodd) that Stage 0 is the most important to preserve.

[RealKerbal3x]

7 minutes ago, Damien_The_Unbeliever said:

The idea that the SpaceX engineers wouldn't be building off of the decades of experience since  N1, in ignorance of N1, and not have any idea of how to protect their systems...

Thank goodness a random Internet commenter is here (a random game forum) to set them right.

This. The train of thought here seems to be 'lots of engines = bad'

Starship was not built with 1960s Soviet technology. It does not use single-use engines that cannot be static fired before launch. It does not have a poorly programmed flight computer.

If you're going to criticise SpaceX, go ahead, but consider that their engineers just might know what they're doing

[Beccab]

Just now, RealKerbal3x said:

The train of thought here seems to be 'lots of engines = bad'

27 engines on Falcon Heavy working without an issue from the very first flight is okay, but add two more as with Superheavy and it has to explode

[mikegarrison]

It wasn't the number of engines that killed the N1, it was (among other issues) the lack of computers to handle engine problems. Both flights ultimately failed when the KORD system commanded all engines to shut down.

[Staticalliam7]

Anyone know how many starlink satellites starship can carry (just out of curiosity) 

[Beccab]

4 minutes ago, Staticalliam7 said:

Anyone know how many starlink satellites starship can carry (just out of curiosity) 

Should be able to get 400, for sure more than 300 (not instantly obviously, but in the first or second year)

Edited September 26, 2021 by Beccab

[Staticalliam7]

1 minute ago, Beccab said:

2 minutes ago, Staticalliam7 said:

Anyone know how many starlink satellites starship can carry (just out of curiosity) 

Should be able to get 400, for sure more than 300

Sheesh. Guess getting a large number of sats won't be as difficult once starship is making regular flights

[pmborg]

9 minutes ago, Staticalliam7 said:

Anyone know how many starlink satellites starship can carry (just out of curiosity) 

While Falcon 9 in a normal flight profile fly about 60, but in January 2021, a new record was set with 143 into orbit in a single launch, for a specific orbit.

The range is between 340 kilometers to 614 kilometers.

But now the Gen2 Starlinks are larger and generate more power than originally

Starship 1.0 LEO, will be able to deliver in orbit between 400 and 1000 depending of the orbit, using the next starlink generation.

 

[tater]

47 minutes ago, pmborg said:

While Falcon 9 in a normal flight profile fly about 60, but in January 2021, a new record was set with 143 into orbit in a single launch, for a specific orbit.

F9 did not launch 143 Starlinks. That was Transporter-1, the rideshare flight, those were cubesats.

 

[SpaceFace545]

What’s the rough orbital life for a starlink satellite. Of course once the propellant runs dry and its orbit starts unavoidably decaying.

[mikegarrison]

7 minutes ago, SpaceFace545 said:

What’s the rough orbital life for a starlink satellite. Of course once the propellant runs dry and its orbit starts unavoidably decaying.

Long time. They use ion thrusters.

[SpaceFace545]

55 minutes ago, mikegarrison said:

Long time. They use ion thrusters.

A year? 3 years, 5 years?

[tater]

2 hours ago, SpaceFace545 said:

What’s the rough orbital life for a starlink satellite. Of course once the propellant runs dry and its orbit starts unavoidably decaying.

I think the point of the thrusters is partially that they reserve deorbit propellant. When they want to decommission it, or it's running low, they lower the orbit.

The only uncontrolled decays would be sats that had a failure that prevents them being properly disposed.

They have what, 3600 m/s dv, and they only need maybe 10% of that or less to deorbit.

[CatastrophicFailure]

2 hours ago, SpaceFace545 said:

A year? 3 years, 5 years?

Around 5 years is the expected lifespan, when they’ll be intentionally deorbited and replaced with a new, better generation. 

[RyanRising]

And if they do fail out in their final orbit, I think it’s about 500km, and the satellites are very draggy cause of that solar panel, so probably around 2-3 years to deorbit naturally? Maybe up to 5? NASA says satellites around 500km could take a decade to deorbit, but I imagine the typical ones they had in mind were a little more dense.

Edited September 27, 2021 by RyanRising

[Beccab]

The suborbital farm received LOX today, it didn't happen since they static fired B3. Looks like we'll be getting some S20 testing today!

[pmborg]

8 hours ago, tater said:

F9 did not launch 143 Starlinks. That was Transporter-1, the rideshare flight, those were cubesats.

 

Yes true 133 client satelites plus 10 starlinks