totm nov 2023 SpaceX Discussion Thread

[JoeSchmuckatelli]

Edit: ALTHOUGH... There could be a 'use booster' followed by a bespoke, not SS, parachute plus system to do something like the Chinese did with their moon sample return. 

(I'd call Booster a proven LEO first stage capable craft at this point) - which, while SX wants to keep developing as part of the SS program - there is no reason why some entity (NASA) couldn't buy one / rent one for a non-SS mission) 

... 

In fact - can we agree that IT-4 is game changing?  Humans simply need a working second stage to put 100+tons into orbit, right? 

Theoretically both Booster and SS can be considered working orbital class expendable rockets - right? 

Edited June 7 by JoeSchmuckatelli

[AckSed]

1 hour ago, JoeSchmuckatelli said:

In fact - can we agree that IFT-4 is game changing?  Humans simply need a working second stage to put 100+tons into orbit, right? 

Theoretically both Booster and SS can be considered working orbital class expendable rockets - right? 

I'll take this action.

There is a wrinkle in that Superheavy is likely flying a lofted trajectory in order to RTLS, so you would need a more powerful second stage like the Starship to circularise the orbits... but I'd like to think we could make a pseudo-Centaur out of an extra-wide F9 second stage and two Merlin Vacuums on the bottom.

Hell, even if we don't have a payload, we have an orbital space truck in the Falcon 9, so you could strip the reentry hardware, install a docking port in the payload bay of a naked Starship , fit it out and fly up as a one-shot space station, ready for the Dragon to dock.

If it works for Vast, it'd work for Starship Station.

Edited June 7 by AckSed

[JoeSchmuckatelli]

7 minutes ago, AckSed said:

Superheavy is likely flying a lofted trajectory in order to RTLS, so you would need a more powerful second stage like the Starship to circularise the orbits

Good points. 

I'm not a numbers guy - so I'm analogizing Booster with Falcon.  It looks like (reusability aside) that Booster can throw hard enough for a second stage to get orbital.  And it can throw more weight than anything prior (assumption) - with a significant diameter now available to potential users. 

My guesswork is that if a customer came along with a second stage and payload that SX could monetize Booster at any point moving forward. (Some work needed obviously) 

I'm also guessing about SS - which likely had an intentional reentry flight profile - but it's hardly a stretch to guess it could have actually orbited if they wanted to. 

[JoeSchmuckatelli]

OK - maybe I'm off.  Falcon is above 7500 km/h at stage separation whereas Booster was only running 5500.  That would need a beefy second stage - but doable I'm guessing. 

Interestingly, Apollo's 1st stage dropped at 6k.

Someone smarter than me could probably prove / disprove my guesswork 

Edited June 8 by JoeSchmuckatelli

[Ultimate Steve]

Another thing I found while reading old parts of the thread (2018-2019) is the general sentiment that New Glenn would come soon and eat Falcon's lunch. Has not come to pass.

[Exoscientist]

On 6/6/2024 at 10:43 AM, JoeSchmuckatelli said:

I think you might want to reflect on this. 

Maybe two out of all of the test article Raptors had issues - none of them catastrophic. 

Don't fall too in love with your thesis - it's okay to change your assumptions with more data 

 

The Raptor had consistent problems of leaking fuel and catching fire on relights on prior tests of the Starship landing procedure:

 

 Even on the SN15 test that SpaceX called a “success” because it landed without exploding, a fire had developed in a Raptor before it touched down. SpaceX was just able to extinguish the fire before it exploded.

 My opinion, it was mistake for SpaceX to stop these Starship landing tests because SN15 landed without exploding first. The tests should have continued until all Raptors were able to do all the relights needed with no engines catching on fire. That is a necessary requirement for a reliable, reusable engine.

And on IFT-3 and just now on IFT-4 a Raptor exploded on relight during the landing burn.

 SpaceX would do well to remember the famous warning of Richard Feynman after the Challenger disaster, 

“For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled." 

  Bob Clark

 

 

 

[darthgently]

7 hours ago, JoeSchmuckatelli said:

OK - maybe I'm off.  Falcon is above 7500 km/h at stage separation whereas Booster was only running 5500.  That would need a beefy second stage - but doable I'm guessing. 

Interestingly, Apollo's 1st stage dropped at 6k.

Someone smarter than me could probably prove / disprove my guesswork 

Apollo had S-II after the main booster that also separated before circularization or TLI, so kind of apples and oranges.  But an expendable 2nd boost stage could be used with super heavy also I suppose

[Exoscientist]

On 6/6/2024 at 3:02 PM, JoeSchmuckatelli said:

Likely - I doubt that SX wants their prototypes falling into competitor's hands.  That said - they'd honestly have to make the FTS break up the ship to ensure sinking.

 Weird - I can't link to reddit now?  TIL Thousands of shipping containers are lost to the sea each year, and that if the containers cargo weight does not exceed 80% of the containers rated capacity, they will float.

TIL Thousands of shipping containers are lost to the sea each year, and that if the containers cargo weight does not exceed 80% of the containers rated capacity, they will float. : r/todayilearned (reddit.com)

(Super weird - I could not paste the link directly.  Had to drop it into a Word doc and then recopy from there to paste).

Point being; even if not completely water tight (the internal tanks are fluid tight) - any trapped air = buoyancy.

Meaning - if they don't blow the ships, someone will recover (or crash into) one.

VH-MXJ - Dassault Falcon 900EX [055] - Flightradar24

If interested - Reddit thinks this is relevant.

 

 Thanks for that. I was wondering if any of the splashdown areas would be observable from satellite imaging. Planet Labs claims to provide continuous, world wide imaging at 3.7 meter resolution, but I found their coverage quite spotty. I couldn’t find images of the expected landing areas. Perhaps someone would be able to find it.

 

Real-Time Satellite Monitoring with Planet.
With roughly 200 Dove satellites in orbit, PlanetScope Monitoring provides a high-resolution, continuous, and complete view of the world from above, every day.
https://www.planet.com/products/monitoring/

  Bob Clark

[.50calBMG]

1 hour ago, Exoscientist said:

Something something engine version from 2-3 years ago.

 

And the first set of RL-10s ever launched to space exploded because of something unrelated to the engine back in 1962, so starliner is in grave danger of exploding too...

How many times do we have to say that the problems you bring up are from a design that was retired literally years ago, and physically cannot happen anymore? Can this be seen as spam yet?

Edited June 8 by .50calBMG

[CBase]

18 hours ago, Flavio hc16 said:

Hearing from Musk interview with "Ellie in space" at around the 2.20 minutes mark, Elon said that the superheavy or the ship( it's not very clear to me) missed the targhet landing zone by 6 kms, but both landed correctly.

Actually I interpreted his remarks that booster did a very precise and soft landing and therefore he sees a chance to try to grab it already next time. However he needs to discuss it with the team. Probably to see if just anything was off norminal values that would endanger stage 0.

Ship was 6km off from intended location, but again my interpretation of his speach is that they did not intend to hit any location with ship. And seriously I do not think it matters yet from my KSP expierences. Once you have a stable, repeatable reentry and landing phase it is simple to adjust initial reentry trajectory to get very close to the target. If we remember ships first suborbital landing tests we see that they are already very well capable for precision landings, once close enough. So for now their reentry is probably more focused on controling attiude and heat, everything else will come in few successful flights.

[Minmus Taster]

4 hours ago, Exoscientist said:

Even on the SN15 test that SpaceX called a “success” because it landed without exploding,

That was the whole point of the test?

4 hours ago, Exoscientist said:

The Raptor had consistent problems of leaking fuel and catching fire on relights on prior tests of the Starship landing procedure

That was years ago at this point?

4 hours ago, Exoscientist said:

And on IFT-3 and just now on IFT-4 a Raptor exploded on relight during the landing burn.

I wouldn't say these were Raptor issues as much as they are booster issues, that's why they moved to orbital tests quickly, they knew this was going to happen no matter how perfectly Raptor functioned. Remember many of these failures were because of propellant slosh issues in the vehicle, not the engine. On that note the fact that the flight 4 failures (particularly the second one) didn't damage the other engines is a sign that the hardware is tough and should become reliable soon.

[CBase]

20 hours ago, CBase said:

The center 3 engines are most critical part during final landing and do only allow for single failures. Which means you need 96.8% single reliability to have 99.9% against double failure. Is raptor currently up to this ? propably not. But again since the produce more than the 3 critical ones, they might be able to select best performing on final assembly control. So again just by collecting data, correlate to test performance they could get to a point that is acceptable.

Actually I need to rephrase my thoughts after thinking one day about it:

If we want to crew rate starship for propulsive landing, with current limited data as a public we can not deduct a high enough reliability for the raptors. So surprise: Watching early protoypes are not good enough for a crewed mars mission

If we want to crew rate starship as fast replacement for crewed mission around earth, we could add some parachute backups as all current capsules use. Then probably even 2 engines out on starship ascent can be compensated and requirement for raptor reliablity falls to 96.2%. Depending on how we measure it, raptor might be already good enough very close for a crew rated starship with 99.9% ! Booster is stated to allow 3 engines failures, maybe even 4 if they expend it just in case. This means single raptor requirement is 97%. Reasonably certain for near future.

Do I think we have a raptor reliability problem ? No, more a problem to understand how wise SpaceX choice to cluster lot of engines was, because the final few hard percentages do not matter.

 

Edit: Sorry forgot the binomial coefficent for failure modes in initial calculations, too long since I did this.

Edited June 8 by CBase

[Ultimate Steve]

I know I've been in a particularly bone picking mood lately but I saw a Thunderf00t meme and long story short I watched his IFT-4 stream and wow. I knew he had some bad takes, but I assumed he was a couple steps above a conspiracy theorist. It is more like 1-1.5 steps above. Hopefully this will be the last sort of this post I'll be making for a while.

I cannot stress this enough, do NOT take your space news or opinions from this channel. I saw someone posting his stuff earlier but as a summary so you know better:

• Opens stating that this is launch will blow up a billion dollars worth of taxpayer money
• Says they are burning 2 billion a year and will be bankrupt soon (Starlink revenue alone is over 4 billion a year from just normal users)
• Says the only technical challenge to solve with reusability is relighting engines and that the real problems are economic
• So many times he decries something impossible because they haven't reached a certain milestone yet.
• Decries SpaceX for delays, when delays in space are normal, Starship program isn't even abnormally delayed compared to other ambitious programs (SLS, Dragon, Starliner, JWST).
• Constant comparisons to different development programs, still in "must work first try" mode
• "SpaceX has not revolutionized spaceflight" although this does depend on your definition of revolutionize.
• "Everything SpaceX sells is at a loss"
• Holds promotional videos up to the standards of a full flight simulation
• Says the darkness in the engine trail isn't right (To my knowledge has been seen before)
• "Green flash, bad engine ignition" either camera artefact or the metal in the hot stage ring burning
• Confused by shutdown venting of engines
• Mistakes the jettison of the hot stage ring for reaction control thrusters (???)
• "Clearly the booster is not gonna make it, it is in an uncontrolled descent with not enough oxygen left to light up the engines" with no indication of control loss after a lecture of how inaccurate the fuel gauge can be in zero g
• "As a general rule I don't like gases escaping from my rocket" "Gases aren't supposed to be leaking out of a rocket" plenty of valid reasons for that, emptying main tanks for landing, RCS, engine purge
• "We're not gonna see inside the starship because it is a completely empty vessel" Yeah, and?
• Suggests use of AI for writing postgraduate theses (admittedly only for fluff/introductions)
• "The bright white flashing is the engines burning"
• Statements during re-entry: "We've lost attitude control" "And there goes the control" "It's gonna go pop in a second" "It's over" "Send in the clowns" "The feed will go blank in a second" "We've lost aerodynamic control" "It's gone"
• Thinks it is day during the landing
• "This is falling way too slow" during landing, insinuating that it is just a piece of debris, that's about how fast it fell on previous tests, actually faster because it is still decelerating
• Does not realize the ship conducted a landing burn, thinks it hit the ocean
• Thinks the illumination from the landing burn is the ship on fire
• Calls the cheering employees morons
• "This flight has shown that Starship is a complete non starter"
• "Starship has cost 15 billion in government funding" is only true if it actually cost that much and you assume every single government contract went directly to Starship dev, that's like saying my college education cost $15,000 in government funding because I drove buses for the city and used my wages to pay for school.

 

 

In fairness, he does have some valid points:

• Validly debunks lack of orbital refueling on the published Dear Moon flight path (in defense was the possibly the optimistically massed carbon fiber version of Starship, possibly with an expended booster)
• Valid points about Cybertruck, Roadster V2, supersonic electric jet, hyperloop, and Tesla's business practices
• City on Mars is something to be skeptical of
• Launch pads should probably not be as close together as they are in the promotional video
• Does take it all back (talk about the booster failing) when the booster lands successfully
• There has been a tide change with respect to public opinion of Elon
• Gets physics of re-entry correct
• "The top stage doesn't work and it can't get anything to orbit" is a correct, if lacking context, statement (no payload door)
• "You can't do rapid iteration with billion dollar vessels" is a valid statement, but if the 30+ vehicles they have made actually did cost a billion they would be bankrupt.
• "meters per second is the appropriate unit for this" The one thing he said I wholeheartedly agree with.

 

This man is living in another reality.

[JoeSchmuckatelli]

6 hours ago, Exoscientist said:

That is a necessary requirement for a reliable, reusable engine

This is the crux of where your argument goes circular. 

You don't need a 'reliable, reusable engine' when the thing you are trying to create is a 'reliable, reusable engine'. 

When do things need to be reliable?  Answer: when you sell it to other people. *

When does reliability not matter?  Answer: when you are prototyping/inventing the thing. 

With SS+B, SX does not have a product yet. **

Until they do, there is no requirement for anything to actually work. 

Spoiler

During prototyping you are trying to find the ways the thing can go wrong - and fix them.  So it's totally fine for them to fly the thing and find out what's failing during real world application. 

Frankly, all of SX's 'test to failure' and very public failures will likely make it easier for people to believe SS+B are safe and reliable once we see them stop burning and exploding. 

* legally 'reliance' - SX isn't making any legal promises to anyone about these prototypes.  No one is relying on anything.  They only have a duty of care to not let the prototype harm others.  That is it. 

** I have argued above that SX could monetize Booster as a heavy lift expendable first stage.  We've seen two flights where the rocket survives through stage separation.  They COULD claim it to be working (thus a product /service) and customers / insurers can estimate the risk /reward of using Booster against the cost and choose to buy it or not. 

Reusable is another matter. 

[Ultimate Steve]

 

 

[JoeSchmuckatelli]

29 minutes ago, Ultimate Steve said:

 

 

Wow.  Impressive. 

Still have work to do (yes, it was on fire as it landed... But it landed!) 

[StrandedonEarth]

1 hour ago, Ultimate Steve said:

 

 

Videos that end too soon. Need extended clips from both angles!

[Exoscientist]

6 hours ago, .50calBMG said:

 

And the first set of RL-10s ever launched to space exploded because of something unrelated to the engine back in 1962, so starliner is in grave danger of exploding too...

How many times do we have to say that the problems you bring up are from a design that was retired literally years ago, and physically cannot happen anymore? Can this be seen as spam yet?

 The problem is the Raptor is still exploding on relights, as happened on both booster landing burns.

   Bob. Clark

[Minmus Taster]

2 hours ago, Ultimate Steve said:

 

 

Aw, I wanted to watch it tip over : (

[Exoscientist]

27 minutes ago, Minmus Taster said:

Aw, I wanted to watch it tip over : (

 I think it is fairly obvious why they didn’t want to show what happened after that.

 

  Bob Clark

[JoeSchmuckatelli]

6 minutes ago, Exoscientist said:

it is fairly obvious why they didn’t want to show what happened after that

Confused. 

We all assume the plan is to blow it up and sink the remnants. 

There is literally a very small range of possible outcomes from the test flight:

1. Nothing happens 

2. Pad explosion 

3. Liftoff then explosion 

4. Partial flight then explosion 

5. Attempted landing then explosion 

6. Successful landing demonstration then explosion 

7. Successful landing demonstration, failure to explode - floating debris. 

... 

We know that IT-4 did not experience 1-5.

If 6 happened... Is anyone surprised? 

If 7 happened... Are they going to blow it up intentionally or try to recover it? 

[Flying dutchman]

Haters gonna hate

[JoeSchmuckatelli]

1 hour ago, Exoscientist said:

problem is the Raptor is still exploding on relights, as happened on both booster landing burns

Problem for whom? 

[CatastrophicFailure]

20 hours ago, JoeSchmuckatelli said:

Cart? 

Meet Horse! 

Horse? 

Push! 

- not that I don't recognize the promise... But they're going to have to crash 3 into the moon (at least) before landing there, then 3 into Mars before landing (hopefully AFTER deployment of several Starlink constellations) and then figure out ISRU and... 

... 

Big dreams.  2040?  Might buy 2035 if we see Moonshot by 2028.

I would say no, not at all. Once Earth EDL is solved, which they are very near to now, and which is necessary for both Earth and lunar operations, extending that to Mars EDL will be a relatively simple problem. Long before they ever start bending metal for such a mission, they will already have LOADS of data on how Starship handles during a similar entry regime. And now that no mishap report is (likely to be) required for IFT-4, I think we’re going to see the pace of development rapid ramp up, then again after the first successful catch, then again after the first reuse. Just like HLS, a Mars sample return is a natural and “easy” extension of stuff they’re doing anyway. 

[.50calBMG]

2 hours ago, Exoscientist said:

 The problem is the Raptor is still exploding on relights, as happened on both booster landing burns.

   Bob. Clark

I think I'm done using logic here, clearly it's not working.

So... nuh-uh