totm nov 2023 SpaceX Discussion Thread

[tater]

https://twitter.com/elonmusk/status/1081662202124296

8 minutes ago, sevenperforce said:

Elon suggests that the hopper will fly with this mottled appearance but the operational starship will be nice and shiny:

https://twitter.com/elonmusk/status/1081662202124296192

^^for some reason this is not pasting in properly.

Also: https://twitter.com/elonmusk/status/1081676911066017793

 

 

 

[sevenperforce]

8 minutes ago, tater said:

I wonder if you could do EDL with 1 fin down. In his previous talks, he said that what would be the V-stab in the skydiver entry was just for looks (and as a leg, obviously). If the v-stab was ventral instead of dorsal, and it vented fuel (or water) along the belly and fin... maybe it survives fine.

PS--this is literally the most steam punk rocket ever.

Maybe they did some fancy modeling that gives a flight and lift profile which permits fixed fins.

At hypersonic entry, all lift is compression lift; there is no aerodynamic (Bernoulli) lift at all. Increases in atmospheric pressure and decreases in speed both exchange compression lift for aerodynamic lift, but they do so with different functional profiles. The transition from compression to aero may therefore be adjustable based on entry profile. Of course the same thing needs to work on Mars...though on Mars, the thrusters are going to have way more control authority than in the low Earth atmosphere.

Recalling the Shuttle's S-curves...it may be possible to point V-stab ventral and then use roll authority only to execute a controlled tailspin all the way through the compressive-to-aerodynamic transition. Transitioning from prone to tail-first is going to be a challenge regardless. A lot depends on where the CoM is. I do not know that putting the V-stab ventral vs dorsal would produce any difference in lift-induced torque around the CoM in the low atmosphere, though it probably would do so in the upper atmosphere during compressive-lift entry.

Useful comment by Lars from NSF:

Quote

My guess is that these engines are placeholders.. all the connection points for plumbing, mounting, wiring, etc are correct, and their shape is correct, but they aren't intended to be functional since they are a "blend of development and operational parts". By having correct shape and correct interfaces a lot can be ensured to be correct. Engineering drawings don't always let you find every interference. Even if they are from solid models although that helps a lot.

Makes a lot of sense. Getting all the right parts in place so they can swap out with stand-tested flight engines.

[tater]

In really high AoA, the spacecraft is effectively almost tail-down, anyway. They showed that, then a skydiver fall with the spacecraft parallel to the ground, then a 90° flip. Seems like you could eliminate that horizontal bit higher up, and the terminal descent looks more like F9 booster.

[sevenperforce]

Alternately:

Quote

I met someone tonight who worked at SpaceX and she said they are real raptors on there but not full thrust.

 

6 minutes ago, tater said:

In really high AoA, the spacecraft is effectively almost tail-down, anyway. They showed that, then a skydiver fall with the spacecraft parallel to the ground, then a 90° flip. Seems like you could eliminate that horizontal bit higher up, and the terminal descent looks more like F9 booster.

The tailfins must be in stall for the entirety of the aerodynamic regime or the whole vehicle will uncontrollably lawn-dart.

The only way I know to maintain a controlled stall would be a conventional yawed tailspin. From Wikipedia:

Quote

A spin is a special category of stall resulting in autorotation about the vertical axis and a shallow, rotating, downward path. Spins can be entered intentionally or unintentionally, from any flight attitude if the aircraft has sufficient yaw while at the stall point. [1] In a normal spin, the wing on the inside of the turn is stalled while the outside wing remains flying; it is possible for both wings to be stalled but the angle of attack of each wing, and consequently its lift and drag, will be different.[2] Either situation causes the aircraft to autorotate toward the stalled wing due to its higher drag and loss of lift. Spins are characterized by high angle of attack, an airspeed below the stall on at least one wing and a shallow descent.

Tailspins are dangerous for conventional aircraft because most control surfaces are stalled. With very high roll authority via RCS, however, the StarShip may have a better time of it.

[CatastrophicFailure]

 

@sevenperforce you have to “paste as plain text” for Tweets to parse correctly. 

[Mad Rocket Scientist]

The sign is photoshopped in, right?

[StrandedonEarth]

Don't forget the canards on Starship will help bring the nose up for the flip

[CatastrophicFailure]

10 minutes ago, Mad Rocket Scientist said:

The sign is photoshopped in, right?

I think not. Probably don't want any actual Martians sneaking aboard...

Spoiler

 

[Mad Rocket Scientist]

10 minutes ago, CatastrophicFailure said:

I think not. Probably don't want any actual Martians sneaking aboard...

  Reveal hidden contents

 

The color and perspective look off to me. The sign seems to be tilted back, and the reflections don't appear to match.

[CatastrophicFailure]

4 minutes ago, Mad Rocket Scientist said:

The color and perspective look off to me. The sign seems to be tilted back, and the reflections don't appear to match.

ಠ_ಠ

Spoiler

 

[magnemoe]

5 minutes ago, CatastrophicFailure said:

ಠ_ಠ

  Hide contents

 

Was that one of the Saturn 5 3rd stages or some other stuff who came back for an visit but Moon exiled it after some orbits? 
Outside the L1 changing initial trajectory but assuming Moon changed it instead its a lot like the effect there Mun capture an asteroid in KSP and then expel it at later date. 

[CatastrophicFailure]

21 minutes ago, magnemoe said:

Was that one of the Saturn 5 3rd stages or some other stuff who came back for an visit but Moon exiled it after some orbits? 
Outside the L1 changing initial trajectory but assuming Moon changed it instead its a lot like the effect there Mun capture an asteroid in KSP and then expel it at later date. 

No. This was clearly labeled THE JOKE.
Probably what Marvin, there, would have caught if not for the sign...

[magnemoe]

7 minutes ago, CatastrophicFailure said:

No. This was clearly labeled THE JOKE.
Probably what Marvin, there, would have caught if not for the sign...

I know and got the joke, it was fun, but has seen this animation before or something like it because some hardware in solar orbit came back. 

[StrandedonEarth]

Hey, I think I see something at the top....

[tater]

He should've taken the left at Albuquoiky.

[Xd the great]

3 hours ago, CatastrophicFailure said:

Welll, that means no underage space tourists. Thats sad.

[Reactordrone]

1 hour ago, StrandedonEarth said:

Hey, I think I see something at the top....

He usually takes a size 36.

[KSK]

8 hours ago, tater said:

He should've taken the left at Albuquoiky.

Ooooh - I see what you did there you wascally wabbit.

[tater]

The above render of the hopper was from NSF (artist's page on image, worth a look).

From reddit:

 

[Green Baron]

I'd paint a few clouds around it, just below the fins. To give it a more heroic touch ...

[tater]

11 minutes ago, Green Baron said:

I'd paint a few clouds around it, just below the fins. To give it a more heroic touch ...

I'm pretty sure I'd not stand where that figure is minus launch clamps

 

[Mitchz95]

2 hours ago, tater said:

The above render of the hopper was from NSF (artist's page on image, worth a look).

From reddit:

 

Soon...

[DDE]

42 minutes ago, Mitchz95 said:

Soon...

So, this is how liberty dies... should the ULA Sniper fail.

Edited January 7, 2019 by DDE

[CatastrophicFailure]

y’arn’t. 

[tater]