totm nov 2023 SpaceX Discussion Thread

[sevenperforce]

9 hours ago, Beccab said:

For clarity, that's not the QD arm extention: what you're seeng there is going to be part of what will try catching Superheavy

Are you sure? That looks like the QD/stabilization arm extension.

[Beccab]

7 minutes ago, sevenperforce said:

Are you sure? That looks like the QD/stabilization arm extension.

Nope, the QD arm is at the production site and still horizontal .  That's the section with two of those V placed a few meters apart that should go parallel to the tower
 

Booster 6 common dome!

Edited September 12, 2021 by Beccab

[tater]

That would be the part that attaches to the tower, and not the catch arms, I assume (the arms will attach to that framework, which rides up and down)?

[sevenperforce]

15 minutes ago, Beccab said:

22 minutes ago, sevenperforce said:

Are you sure? That looks like the QD/stabilization arm extension.

Nope, the QD arm is at the production site and still horizontal .  That's the section with two of those V placed a few meters apart that should go parallel to the tower

Whoops, yes, you're right; I see that now.

5 minutes ago, tater said:

That would be the part that attaches to the tower, and not the catch arms, I assume (the arms will attach to that framework, which rides up and down)?

Yes, looks like it.

 

[tater]

Then the arms with tank treads attach to that thing, right? I assume? LOL.

Insane (in a good way).

[Lewie]

I really want to hear what some of the higher ups at NASA think of this booster catching business....I know that Spacex has yet to do it, or even finish building it, but I am highly confident that they’ll be able to pull it off. Spacex is sure good at making the impossible possible

[Beccab]

4 minutes ago, Lewie said:

I really want to hear what some of the higher ups at NASA think of this booster catching business....I know that Spacex has yet to do it, or even finish building it, but I am highly confident that they’ll be able to pull it off. Spacex is sure good at making the impossible possible

The HLS NASA people probably believe that they either will do it, find a substitute before Artemis III or that they will have 4-8 full Starships ready and expendable by then

Edited September 12, 2021 by Beccab

[tater]

 

[Beccab]

Some info on Dearmoon from insiders:

- realistic internal NET is 2025 (from the same source that said SpaceX's internal mars manned mission target is 2031)

- Superheavy to be expended on that mission, zero refuelings needed and straight flyby

Edited September 12, 2021 by Beccab

[GuessingEveryDay]

OK

Edited September 13, 2021 by Vanamonde
Don't get carried away with font sizes, please.

[Spaceception]

Nearly there! It looks so nice like that.

How are they going to deal with tiles near those attachment points? Will they install those once its been stacked, or just saving them for last?

Edited September 12, 2021 by Spaceception

[sevenperforce]

Here's my latest render for how the new arms could connect.

If we assume there are yet-unseen hinges at the rails and at the points where the W-shaped system and its arm extensions are currently welded together, then the entire blue frame can rotate while keeping the chopstick-arm attach point substantially underneath the cable lift point of the Drawworks. It looks flimsy, but if the cable is lifting the whole assembly, all the blue frame is really providing is stabilization. The actuators simply rotate; they aren't load-bearing at all.

Also depicted is the hypothetical tank treads to translate the booster catch pegs. Full image here.

27 minutes ago, tater said:

 

Wow. That's just absolutely gorgeous. I ream really, really liking the tile work across the top of the cowling on the forward eloneron. 

Just now, Spaceception said:

How are they going to deal with tiles near those load points? Will they install those once its been stacked, or just saving them for last?

We know they can use the Frankencrane to stack Starship on top of Superheavy using those load points, but there is no lift truck that can reach the top of Starship when it is fully stacked. I don't know whether Frankencrane is human-rated or not; if so, they could dangle a work platform there so that workers could remove the load hooks and glue on the remaining tiles (but that seems super sketchy).

I'm very curious about the missing tiles underneath S20's forward elonerons. It seems like that might be a place to attach lift pegs similar to the ones on Superheavy. If so, then they can remove the load hooks and finish the heat shield while S20 is still on the ground, then wheel it over to the launch tower and use the chopstick arms (once installed) to lift Starship on top of Superheavy. They'd just have to expect the lift pegs to burn off on re-entry.

Elon has said they need the QD arm fully installed and functional in order to properly stabilize Superheavy during the final stacking for launch (and to provide propfill for Starship), but I don't think he has said for sure whether the chopstick arms are required. If Frankencrane is human-rated then maybe they will leave the chopstick arms off for the time being and just launch that way.

[magnemoe]

3 hours ago, tater said:

Then the arms with tank treads attach to that thing, right? I assume? LOL.

Insane (in a good way).

That looks like the claw to me, its center is circulate to catch an circular object. It will then be attached to an articulated arm with at least two joints or an way to telescope it. It mounted an frame who can move up and down. 
The tank treads is to rotate SH after catching. Its no problems curving them, think of an bicycle chain laid flat and the center pins in slots. 
Downside is that you need to make this strong to handle the catch. But you could raise this up some cm after you catch and secure. 

[tater]

25 minutes ago, sevenperforce said:

Here's my latest render for how the new arms could connect.

I think the entire grabber you have rendered needs to move towards the tower. The point where the "chopsticks" meets the "claw" carrier assembly touches the corner of the tower, then those arms with the curv come around and engage the 2 side rails from behind.

Vs where you have it, which is directly under the nose that will hold the cables.

If that makes sense.

 

Q&D edit

[Silavite]

1 hour ago, Lewie said:

I really want to hear what some of the higher ups at NASA think of this booster catching business....I know that Spacex has yet to do it, or even finish building it, but I am highly confident that they’ll be able to pull it off. Spacex is sure good at making the impossible possible

Has Bill Gerstenmaier talked about it at all? He's with SpaceX now, but he's the first person that comes to mind linking senior NASA folks and SpaceX.

[sevenperforce]

34 minutes ago, magnemoe said:

That looks like the claw to me, its center is circulate to catch an circular object.

We know the chopsticks will catch the booster by the pegs. No need for a claw. Also, you don't want a circular claw anyway, because that results in fewer degrees of freedom. Parallel chopsticks can catch the booster anywhere as long as it comes down between them; a circular claw can only catch at a single point in 3D space.

26 minutes ago, tater said:

I think the entire grabber you have rendered needs to move towards the tower. The point where the "chopsticks" meets the "claw" carrier assembly touches the corner of the tower, then those arms with the curv come around and engage the 2 side rails from behind.

Vs where you have it, which is directly under the nose that will hold the cables.

If that makes sense.

The lift point remains a thorny problem. You need the rotation axis of the chopstick arms to be directly under the Drawworks cable lift point. So it HAS to be further out than that.

[Silavite]

I must admit that this whole catching mechanism is making me say something I never thought I'd say... it's got me interested in a structures problem! (No offense to any structures people here .)

[tater]

 

[Guest The Doodling Astronaut]

21 minutes ago, tater said:

 

Kinda makes sense that they aren't doing too many renders ATM. They want to be a real company not a paper company. I actually think it's great that it's other people making the renders not SpaceX

[JoeSchmuckatelli]

Also - grid fins should be stowed for launch n'est cie pas? 

[HvP]

I'm curious as to how accurately the booster can control roll on the way to the catching mechanism.

It seems to me that even a very small rotation along the roll axis can move the catch points several degrees inward/outward around the barrel of the booster. If the catching arms are tangentially straight where they meet the side of the booster then they are likely to miss the catch points entirely unless roll control is perfect.

A curved catching claw would solve this problem, but it doesn't allow for those tank treads which they want to move the booster in and out.

[cubinator]

4 minutes ago, JoeSchmuckatelli said:

Also - grid fins should be stowed for launch n'est cie pas? 

Not this time. 

The grid fins don't add a lot of drag when deployed, but the mechanism to fold them up does add a lot of mass. By taking out the requirement to fold the fins, they save a lot of mass for a minimal loss. So the grid fins on the booster will not fold up.

[JoeSchmuckatelli]

1 hour ago, cubinator said:

The grid fins don't add a lot of drag when deployed

Color me perplexed 

[Nothalogh]

25 minutes ago, JoeSchmuckatelli said:

Color me perplexed 

Relative to the rest of the combined vehicle

[StrandedonEarth]

1 hour ago, JoeSchmuckatelli said:

Color me perplexed 

The whole thing has been counter-intuitive all along, first the switch to stainless, and now this. It goes back to the best part is no part, and folding the grid fins requires extra mass, extra parts, and extra engineering efforts to save what is actually an insignificant amount of drag (compared to the effort to eliminate it).