totm nov 2023 SpaceX Discussion Thread

[cypher_00]

Kinda happy it got scrubbed.. didn't see the launch warning on my phone. I would have missed a launch after seeing 4 launches live.. hope i don't miss it again tomorrow...

[StrandedonEarth]

10 minutes ago, Ultimate Steve said:

The accelerometers being installed upside-down.

Not just installed, hammered in upside-down

[tater]

 

 

[XB-70A]

Just coming back from the Northern spotting site.

There was a strange atmosphere there, somewhat a mixture of fun and sadness. Anyway, it was a great occasion to take a good sunbath 

Some pictures taken today:

One of the official Huey passing over the beach. I don't know what I would give to get a trip with them one day.

 

 

 

Surprisingly, at the time I started my car the song chosen by my old iPod was Don't Leave Me Now from Supertramp...

Edited May 11, 2018 by XB-70A

[ThatGuyWithALongUsername]

2 hours ago, Delay said:

Block 5 is off to a fantastic start...

I blame your username

2 hours ago, NSEP said:

So its not the rocket?

Pfew...

Phew indeed... very relieving. They can't afford to have problems with the block 5's design.

And of course (if it launches at the beginning of its window) I can't see it launch tomorrow either, lol.

[tater]

Hard to understand the audio, but he said they have some active water cooling on the vehicle.

Confident that they can achieve S2 reusability, it's only a matter of mass penalty, and that they don't want to spend a lot of engineering work on it if it impacts BFR negatively at all. Also, they won't do S2 reuse if it has any chance of lowering reliability on ascent.

Not impossible to get the marginal launch costs of F9 down to 5-6 M$.

[tater]

 

[sevenperforce]

3 hours ago, Ultimate Steve said:

The accelerometers being installed upside-down.

That failure will go down (see what I did there?) in history.

The best part is, you can see what is wrong when you watch the launch.

[tater]

 

[CatastrophicFailure]

47 minutes ago, sevenperforce said:

That failure will go down (see what I did there?) in history.

The best part is, you can see what is wrong when you watch the launch.

You see, Ivan, when install thing backward you... um... er...

...nevermind, just run, I hear Kommissar coming...

Quote

...30-50 Block 5s...

Ok, they seriously need to give real names to these things! 

[Streetwind]

Shamelessly stolen from Reddit:

Quote

Full conference call highlights

• Really the 6th iteration of F9
• 8% increase in thrust of S1
• Last major revision
• Up to 300 more flights with block 5
• 2nd stage has block 5 engine but will operate like a block 4 for this flight
• The interstage looks cool
• Re-flying same block 5 core within 24 hours next year
• Leg 2.0
• No more aluminum grid fins
• Elon confident that full reusability of the Second Stage is achievable.
• Gaining data about 2nd stage entry now. They transmit to the Iridium constellation
• Will add thermal protection system to 2nd stge
• Fuel costs $300,000-400,000. Still hoping to get the marginal cost of a Falcon 9 launch down to $5-$6 million.
• First stage 60 percent of cost, 2nd stage 20, fairing 10, everything else 10
• Expecting no unnecessary action between flights. Fold up legs, attach 2nd stage and go.
• First block 5 to 10 flights most likely next year. Big milestone Elon says.
• Need to take this booster apart after this flight since it's the first Block 5
• Human rated rockets must be overdesigned by 40% for crew safety
• Boca Chica will be re-dedicated to BFR
• 30 to 50 Block 5 cores planned
• SpaceX charging $50 million for flight proven flight, instead of $62 million for a new one.
• NASA can be a pain in the ass sometimes
• Load and Go issue has been overblown. CAN load fuel and then have astronauts board
• Massive amount of research and testing in COPV 2.0. Most advanced pressure vessel ever developed by humanity.

Emphasis not mine, this is a direct quote.

 

Edited May 11, 2018 by Streetwind

[mikegarrison]

Most advanced pressure vessel ever developed by humanity.

Elon has a touching faith that he and his company are the only ones who have ever solved complicated problems before. Meanwhile, those of us who have some idea of what it takes to design and build the pressure vessel known as an "airplane fuselage" are, shall we say, doubting the accuracy of his assertion.

[CatastrophicFailure]

8 minutes ago, mikegarrison said:

Most advanced pressure vessel ever developed by humanity.

Elon has a touching faith that he and his company are the only ones who have ever solved complicated problems before. Meanwhile, those of us who have some idea of what it takes to design and build the pressure vessel known as an "airplane fuselage" are, shall we say, doubting the accuracy of his assertion.

In all fairness, pressurized airplane fuselages have been around for nearly a hundred years, and haven’t changed all that much. The stresses in a high-pressure helium tank are just a bit higher...

[mikegarrison]

56 minutes ago, CatastrophicFailure said:

In all fairness, pressurized airplane fuselages have been around for nearly a hundred years, and haven’t changed all that much. The stresses in a high-pressure helium tank are just a bit higher...

Haven't changed that much?

 

[kerbiloid]

Spoiler

2 hours ago, mikegarrison said:

 

 

They used to repair the hull with duct tape.

Until they realized, that they can just wind a whole hull of duct tape.

 

Edited May 11, 2018 by kerbiloid

[KSK]

I presume the pre-penultimate bullet point was a bit of a paraphrase...

Interesting that 2nd stage reuse is firmly back on the agenda, although I remain politely skeptical until I hear it from Gwynne as well. If this has already happened, could some kind soul point me at a source.

 

[Hannu2]

3 hours ago, mikegarrison said:

Haven't changed that much?
 

No, exactly same thing as a one seat plane made of sticks and canvas from 100 years ago. Real differences are in gas bottles. Old ones are metal or composite cylinders with hemispherical heads but new ones are... hmmm... composite cylinders with hemispherical heads and magic touch from SpaceX's main wizard Musk.

[Wjolcz]

Shouldn't composites be easier to work with? You don't have to heat carbon fiber up. Production of it might be problematic though.

[sevenperforce]

8 hours ago, CatastrophicFailure said:

You see, Ivan, when install thing backward you... um... er...

...nevermind, just run, I hear Kommissar coming...

Obligatory: In USSR, gyroscope install you.

5 hours ago, Streetwind said:

Shamelessly stolen from Reddit:

• 8% increase in thrust of S1

So this is major. I was expecting a 2-4% increase in S1 thrust; 5% at most. Bumping up thrust by a whopping 8% directly cuts gravity drag by 7.5%. On a nominal GTO launch, that means up to 109 m/s more can be added to the second stage at staging, simply by virtue of higher liftoff thrust. If S2 starts with 109 m/s more, it can push a 6% larger payload to GTO, or it can push the same payload to a 22% higher (!!!!) apogee.

Incidentally, this will make RTLS more challenging because the first stage will be further downrange and moving faster.

@tater Perhaps that's why RTLS actually is always harder on the booster: in order to reverse direction, the S1 has to do a three-engine full-throttle boostback as soon as possible, which probably means extremely high gees and corresponding stresses. Boostback on ASDS landings, when they happen, are more like trajectory corrections than anything else and can probably be done at slightly lower throttle. Of course they are also much shorter in duration.

6 hours ago, Streetwind said:

• Elon confident that full reusability of the Second Stage is achievable.
• Gaining data about 2nd stage entry now. They transmit to the Iridium constellation
• Will add thermal protection system to 2nd stge

Not too long ago, even Elon was saying they merely wanted to recover the second stage for testing. Now he is back to full reuse.

That would be epic for sure. Neat that Iridium is letting them use the constellation as a relay during entry; I assume this means current vehicles have additional instrumentation added to S2.

Wonder if the TPS will be external (visible on launch) or inside the fairing/interstage. I'm guessing they will not attempt S2 recovery on Dragon flights, in order to keep the man-rated vehicle design frozen. If not, then it will definitely need to be internal.

6 hours ago, Streetwind said:

• First block 5 to 10 flights most likely next year. Big milestone Elon says.

"Big milestone" is putting it lightly.

6 hours ago, Streetwind said:

• 30 to 50 Block 5 cores planned

"Nah, we only need to build a few dozen rockets to fulfill a bigger launch manifest than all other worldwide launches combined. No biggie."

6 hours ago, Streetwind said:

• SpaceX charging $50 million for flight proven flight, instead of $62 million for a new one.

....whoa.

That's huge.

Huger than huge.

6 hours ago, Streetwind said:

• Load and Go issue has been overblown. CAN load fuel and then have astronauts board
• Massive amount of research and testing in COPV 2.0. Most advanced pressure vessel ever developed by humanity.

Yeah, the subchilled performance boost and greater propellant load isn't required for ISS flights. But I still say loading astronauts first is, technically, safer. Though NASA's not exactly going to listen to me.

I do believe the hype on COPV 2 being "most advanced". This is their pain point.

3 minutes ago, Wjolcz said:

Shouldn't composites be easier to work with? You don't have to heat carbon fiber up. Production of it might be problematic though.

Composites can't really be molded or changed after it's created, though.

The biggest problem is that composites are technically flammable. Which is not a nice thing to have in a tank full of LOX.

[sh1pman]

11 minutes ago, sevenperforce said:

So this is major. I was expecting a 2-4% increase in S1 thrust; 5% at most. Bumping up thrust by a whopping 8% directly cuts gravity drag by 7.5%. On a nominal GTO launch, that means up to 109 m/s more can be added to the second stage at staging, simply by virtue of higher liftoff thrust. If S2 starts with 109 m/s more, it can push a 6% larger payload to GTO, or it can push the same payload to a 22% higher (!!!!) apogee.

I think the dry mass got higher as well, due to all of these added things like reinforced octaweb, new legs, titanium fins, TPS on both first AND second stages, and other improvements meant to human-rate the rocket (making everything 40% sturdier than needed).

[sevenperforce]

5 minutes ago, sh1pman said:

I think the dry mass got higher as well, due to all of these added things like reinforced octaweb, new legs, titanium fins, TPS on both first AND second stages, and other improvements meant to human-rate the rocket (making everything 40% sturdier than needed).

I doubt there was any appreciable increase in dry mass. Maybe 0.5-1% at most. The new legs are lighter, not heavier, and the octaweb is the same weight (it's simply bolted rather than welded now). No TPS on S2 yet. The new grid fins are probably not much heavier than the old ones; titanium is stronger than aluminum.

[sh1pman]

6 minutes ago, sevenperforce said:

The new grid fins are probably not much heavier than the old ones; titanium is stronger than aluminum.

They are bigger and denser than the aluminum ones, so they must be quite a bit heavier. After all, they are the biggest pieces of cast titanium in existense.

Edited May 11, 2018 by sh1pman

[sevenperforce]

5 minutes ago, sh1pman said:

They are bigger and denser than the aluminum ones, so they must be quite a bit heavier. After all, they are the biggest pieces of cast titanium in existense.

They are about 40% heavier but that is a tiny blip compared to the dry mass of S1, let alone the wet mass. You could literally double the dry mass of the first stage and it would only reduce liftoff TWR by about 3.8%.

Plus, they've already been flying titanium grid fins on Block 3 and Block 4. The bigger grid fins actually pay for themselves in terms of weight reduction because they allow the stage to glide back with higher AoA, saving fuel.

[Technical Ben]

6 hours ago, mikegarrison said:

Most advanced pressure vessel ever developed by humanity.

Elon has a touching faith that he and his company are the only ones who have ever solved complicated problems before. Meanwhile, those of us who have some idea of what it takes to design and build the pressure vessel known as an "airplane fuselage" are, shall we say, doubting the accuracy of his assertion.

Aircraft vs fuel tank is like saying you know what a car is because you make horses...

 

(Ok, that example is poor, but it's like comparing a car fuselage to an aircraft one. I've seen the local tanker factory... and even they do VASTLY different construction depending on the type or haulage.)

Edited May 11, 2018 by Technical Ben

[sh1pman]

22 minutes ago, sevenperforce said:

They are about 40% heavier but that is a tiny blip compared to the dry mass of S1, let alone the wet mass. You could literally double the dry mass of the first stage and it would only reduce liftoff TWR by about 3.8%.

If you double the dry mass, stage delta-v drops from 3.9 km/s to 3.5 km/s if the first stage is expended, or from 2.9 km/s to 1.9 km/s with RTLS (I've spent all this time doing the calculations!).

That's a lot. S1 dry mass is critical to their ability to recover and reuse boosters.