totm nov 2023 SpaceX Discussion Thread

[AckSed]

SpaceX has a new, lighter Starlink satellite with upgraded hardware: https://spaceflightnow.com/2025/01/18/live-coverage-spacex-to-launch-27-starlink-satellites-on-falcon-9-rocket-from-california/

[magnemoe]

9 hours ago, Superpluto126 said:

I think for Payloads that can't use the Pez dispenser SpaceX will Pursue one of 2 options

1. A Larger Version of the Pez dispenser, it will be capable of launching Medium sized SATs in decent sized numbers. I don't see why this wouldn't be possible but it might require an extensive re-design of the Rings used to construct the ships.

2. Fully Expendable ship with ride share like payload as it will have a  LOT of payload capability. Probably stretched as well like V3, if a Payload is so big it takes up the entire Bay then that's gonna be a option as well.

I assume an large payload door, not an fan of the whale mouth design as it would be an pain to load cargo bay on the ground. with side hinges you can have an hinge all the way up one straight side. 
Using an medium sized door would require quite some dispenser system who would easy be heavier and less reliable in releasing the satellite. If your door don't close after releasing my satellite its your problem  

[darthgently]

LM2 is bearing arms now

 

[Exoscientist]

On 1/17/2025 at 4:42 PM, darthgently said:

Nope.

The jet of flame observed running up the side of the Super Heavy booster moments before it is caught by the launch mount is primarily due to methane (CH4) burnoff. This phenomenon occurs because the booster lands with excess fuel, specifically more methane than can be acceptably dumped into the atmosphere. As the booster approaches the landing phase, it vents fuel to avoid overpressurization, and this methane can ignite, creating the visible flame. This process is part of the landing burn strategy, where the booster slows down using its engines, and the venting and subsequent ignition of excess methane contribute to the visible flame and smoke.

https://www.adastraspace.com/p/spacex-super-heavy-catch

 

 Thanks for that link. If you read the section “Let’s talk about the black smoke and fire”, you’ll see there is some uncertainty as to whether all the flames were intentional venting or not. The author notes there was also black smoke from the rear of the rocket, which could have been thermal protection burning or some other parts in the engine bay including the engines on fire.

 As the author notes, all this could be resolved if SpaceX would say what happened, but SpaceX ain’t telling.

   Bob Clark

[Codraroll]

18 hours ago, Exoscientist said:

As the author notes, all this could be resolved if SpaceX would say what happened, but SpaceX ain’t telling.

And as literally everybody else in this thread note constantly, all this could also be laid to rest if you didn't see bogus indications of poor Raptor reliability in every shadow, lens flare, and grain of sand out there, then jumped in here to tell us that this time, your wild guess is bulletproof evidence that SpaceX is hiding this very specific thing from all of us you in particular.

[tater]

SpaceX wants to blow up rockets. For profit. Or something .

[darthgently]

Some days I want to forward some of these theories to Tom Mueller so he could get a good laugh.  But he’d probably just wonder why some stranger was sending him nonsense

[darthgently]

I thought these had been installed the other day with the “god” pin but I guess that was just completing the subassembly.  Now they are being installed

 

[JoeSchmuckatelli]

Just in case you were wondering, "What happened to the Roadster"...

Near-Earth "Asteroid" Spotted By Astronomers Turns Out To Be Elon Musk's Car

On January 2, the International Astronomical Union's Minor Planet Center announced the discovery of a new asteroid. The object was dubbed 2018 CN41 after the year and month when the telescope observations took place. The "asteroid" has an eccentric orbit, which qualified it as a Near-Earth Object (NEO), taking it within the Moon's orbit at a distance less than 240,000 kilometers (150,000 miles) from Earth. 

While still undisputedly an object near Earth, the Minor Planet Center issued a correction the following day after they confirmed it was in fact Elon Musk's own Tesla Roadster, which he famously launched into space in February 2018, attached to the Falcon Heavy Upper stage booster.

Near-Earth "Asteroid" Spotted By Astronomers Turns Out To Be Elon Musk's Car | IFLScience

[JoeSchmuckatelli]

Edit - you know... I just realized I fell for "Old News, recycled as New News".  Did not recognize that until just now.

 

[Exoscientist]

2 hours ago, darthgently said:

Some days I want to forward some of these theories to Tom Mueller so he could get a good laugh.  But he’d probably just wonder why some stranger was sending him nonsense

 Someone needs to actually ask SpaceX about it, since SpaceX is not telling.

A photographer took another angle of the flight 7 landing burn that showed also for this latest landing there was a large plume of flame shooting up the side:

 

 From the angle the SpaceX live feed showed, the size of the flame was not visible.

   Bob Clark

[StrandedonEarth]

It would be interesting to know the shutdown sequence for the engines. I’m going to guess that they shut the flow of lox first, so the flames are simply the excess methane burning off. Burning methane is probably easier on the hot engines than having them attacked by pure oxygen 

[darthgently]

49 minutes ago, JoeSchmuckatelli said:

Edit - you know... I just realized I fell for "Old News, recycled as New News".  Did not recognize that until just now.

 

IFLScience can do that

[Exoscientist]

1 hour ago, StrandedonEarth said:

It would be interesting to know the shutdown sequence for the engines. I’m going to guess that they shut the flow of lox first, so the flames are simply the excess methane burning off. Burning methane is probably easier on the hot engines than having them attacked by pure oxygen 

 You have to guess that since SpaceX ain’t telling.

  Bob Clark

[magnemoe]

6 hours ago, StrandedonEarth said:

It would be interesting to know the shutdown sequence for the engines. I’m going to guess that they shut the flow of lox first, so the flames are simply the excess methane burning off. Burning methane is probably easier on the hot engines than having them attacked by pure oxygen 

Makes some sense, kind of Delta heavy launch. 

[Deddly]

7 hours ago, Exoscientist said:

 

Delta IV heavy used to go up in flames every launch. I guess that didn’t bode well for the RS-68A.

[Exoscientist]

1 hour ago, Deddly said:

Delta IV heavy used to go up in flames every launch. I guess that didn’t bode well for the RS-68A.

That’s from flames bouncing up from the ground. You don’t see that at altitude. More relevant though are rockets that do landing burns. Not many but none of DC-X, New Shepard, or SpaceX’s own Falcon 9 have huge plumes of flame shooting up the side during their landing burns. 
 

  Bob Clark

[StrandedonEarth]

1 hour ago, Exoscientist said:

That’s from flames bouncing up from the ground. You don’t see that at altitude. More relevant though are rockets that do landing burns. Not many but none of DC-X, New Shepard, or SpaceX’s own Falcon 9 have huge plumes of flame shooting up the side during their landing burns. 
 

  Bob Clark

Actually, in the case of DIVH, that's excess H2 from the startup sequence burning off. Neither DC-X or NS shut down engines during the landing burn, and F9 doesn't use an easily vaporized (vapor at room temp) fuel

[Ultimate Steve]

1 hour ago, Exoscientist said:

That’s from flames bouncing up from the ground. You don’t see that at altitude.

During engine startup, hydrogen is flowed through the RS-68s for several seconds to prevent anything becoming oxygen rich (i.e. catastrophically bad) during the startup sequence. Scott Manley has a good video on this: 

I'm not completely sure why the RS-68 is the only notable example of an engine that does that at liftoff. Surely there are other gas generator hydrogen engines. Might have something to do with its cycle. But in general, engines sometimes vent in strange and often engine-specific ways during engine startup and engine shutdown, which is often visible as a lot of fire.

Here are some examples of flames after engine shutdown.

The BE-3:

The RS-25:

The F-1 (not high quality but definitely there):

I also looked at Merlin and RL-10, they don't appear to have particularly pronounced shutdown behaviors, so it is definitely an engine-by-engine thing. I believe there are also engines that run a purge with an inert gas either before or after ignition. There's a lot of ways to start up and shut down a rocket engine.

Raptor breaks the mold a little as its shutdown plume is particularly pronounced. I am not sure why this is:

If you need more to convince yourself that this is normal for Raptor, and that they can again fire the engine after an event like this, here is a time lapse of Raptor firing 34 times in rapid succession with <10 second cooldowns between firings, with a large fireball after each one:

Unusually large, yes. But it appears to be how Raptor normally shuts down.

2 hours ago, Exoscientist said:

More relevant though are rockets that do landing burns. Not many but none of DC-X, New Shepard, or SpaceX’s own Falcon 9 have huge plumes of flame shooting up the side during their landing burns. 

(Note: The DC-X video I was able to find is too low quality to determine shutdown characteristics, the video of RL-10 test firings wasn't great either so I can't say for certain if the RL-10 has a pronounced shutdown fireball or not)

Correct, but none of those rockets have engine shutdowns during their landing burns. Raptor's normal shutdown fireball is already massive, and the picture in question was taken just after ten of them shut down.

As for why the flame was only on one side, I am 99% sure this is due to air resistance, as the booster was traveling sideways towards the catch tower and the flame would tend to be pushed behind. This is also why the flame is above the engines and not below them as the booster is traveling down (helped along by the fact that methane is less dense than air).

11 hours ago, Exoscientist said:

From the angle the SpaceX live feed showed, the size of the flame was not visible.

Did you even watch the video???

And as we would expect from a transient shutdown plume from other videos of Raptor firing, the plume dissipates moments later:

 

Don't get me wrong, I am also frustrated by SpaceX's lack of technical transparency. I would love to read through a 100 page report on the failure of flight 1. I want all the details. Though I think what we've gotten from SpaceX is still a little better than what we've gotten from other private US space companies, though I may being swayed by their top tier video coverage.

But for some reason you always jump to a conspiracy without taking the time to think of plausible explanations or to even double check the basic facts you are basing your arguments off of.

[Exoscientist]

1 hour ago, Ultimate Steve said:

During engine startup, hydrogen is flowed through the RS-68s for several seconds to prevent anything becoming oxygen rich (i.e. catastrophically bad) during the startup sequence. Scott Manley has a good video on this: 

I'm not completely sure why the RS-68 is the only notable example of an engine that does that at liftoff. Surely there are other gas generator hydrogen engines. Might have something to do with its cycle. But in general, engines sometimes vent in strange and often engine-specific ways during engine startup and engine shutdown, which is often visible as a lot of fire.

Here are some examples of flames after engine shutdown.

The BE-3:

The RS-25:

The F-1 (not high quality but definitely there):

I also looked at Merlin and RL-10, they don't appear to have particularly pronounced shutdown behaviors, so it is definitely an engine-by-engine thing. I believe there are also engines that run a purge with an inert gas either before or after ignition. There's a lot of ways to start up and shut down a rocket engine.

Raptor breaks the mold a little as its shutdown plume is particularly pronounced. I am not sure why this is:

If you need more to convince yourself that this is normal for Raptor, and that they can again fire the engine after an event like this, here is a time lapse of Raptor firing 34 times in rapid succession with <10 second cooldowns between firings, with a large fireball after each one:

Unusually large, yes. But it appears to be how Raptor normally shuts down.

(Note: The DC-X video I was able to find is too low quality to determine shutdown characteristics, the video of RL-10 test firings wasn't great either so I can't say for certain if the RL-10 has a pronounced shutdown fireball or not)

Correct, but none of those rockets have engine shutdowns during their landing burns. Raptor's normal shutdown fireball is already massive, and the picture in question was taken just after ten of them shut down.

As for why the flame was only on one side, I am 99% sure this is due to air resistance, as the booster was traveling sideways towards the catch tower and the flame would tend to be pushed behind. This is also why the flame is above the engines and not below them as the booster is traveling down (helped along by the fact that methane is less dense than air).

Did you even watch the video???

And as we would expect from a transient shutdown plume from other videos of Raptor firing, the plume dissipates moments later:

 

Don't get me wrong, I am also frustrated by SpaceX's lack of technical transparency. I would love to read through a 100 page report on the failure of flight 1. I want all the details. Though I think what we've gotten from SpaceX is still a little better than what we've gotten from other private US space companies, though I may being swayed by their top tier video coverage.

But for some reason you always jump to a conspiracy without taking the time to think of plausible explanations or to even double check the basic facts you are basing your arguments off of.

 

 

 To get to the bottom of it the FAA should require SpaceX to release all videos of the engine bay while the engines are firing, most specifically during restarts.

  Bob Clark

Edited Tuesday at 02:47 PM by Exoscientist

[darthgently]

28 minutes ago, Exoscientist said:

To get to the bottom of it the FAA should require SpaceX to release all videos of the engine bay while the engines are firing, most specifically during restarts.

Even if developed by NASA instead of privately you would not have access to this data at this time.  Because ITAR.

It is an unreasonable demand and the only people who would profit from it significantly are perhaps people in the Thousands Talents or similar career track

[AckSed]

59 minutes ago, darthgently said:

people in the Thousands Talents or similar career track

Side question: what are the Thousand Talents?

[Ultimate Steve]

1 hour ago, Exoscientist said:

Ignores all points made, deflects by again posting the same video of a likely unrelated phenomenon from a mission nearly 4 years ago, several major ship versions ago, and one major engine version ago. Finishes with a statement calling for the release of information, vaguely alluding to something hidden.

You are welcome to, you know, just ask the FAA for information: https://www.faa.gov/foia

[darthgently]

13 minutes ago, AckSed said:

Side question: what are the Thousand Talents?

You are going to have to web search that, my friend

[Cuky]

13 hours ago, Exoscientist said:

 You have to guess that since SpaceX ain’t telling.

  Bob Clark

They are a privately owned company. They are under no obligation to share any technical info with us. Them sharing any technical info that they do (and they do quite a bit) is their good will.