SpaceX (Vol. 2)

[Arnold Cunningham]

annodomini2 said:

It's both, plus there's a sweet spot for rocket engine size, the bigger the engine the more likely it is to have control issues due to complex pressure interactions within the engine.

All the F1 engines on the S5 had to be "calibrated" because of this issue.

Tim dodd has a good video on this.

Yeah, I remember reading about this. Didn't they they end up hand finishing them - I forget which component - since this meant there was less consistency in the spacing of the holes and therefore the dangerous harmonics in the chamber wouldn't set up and destroy the engine.

[skwdenyer]

ColinGreaves said:

I guess there is a tradeoff between complexity and redundancy, SpaceX seems to prefer going to complexity, if you take complexity to be the number of components used.

Is Falcon heavy the rocket with the second largest number of engines? I am not well versed on the multitude of chinese designs.

Complexity (in the sense of making it hard to build a reliable rocket) isn't number of parts; it is number of unique parts.

Lots of common engines, with masses of type flight experience, and then a control system to herd them, isn't complex by rocket standards (or, indeed, by any standards). Yes, each additional component adds a potential point of failure; set against that, Raptor is now a mature, well-understood, well-developed engine.

SpaceX really are doing something different; they're planning to churn out >500 Raptors pa, at <$250k each.

SLS' RS-25 are ~$40m a pop. So $120m for SLS vs <$9m for Super Heavy, in engines alone, and SpaceX get to re-use theirs.

[S6PNJ]

Hill92 said:

Gwynne Shotwell has said today they're going for the 33 engine static fire tomorrow.

Is this going to be streamed anywhere? Neither Everyday Astronaut or SpaceX seem to have a live feed in preparation (or I'm looking in the wrong place!).

[MartG]

S6PNJ said:

Hill92 said:

Gwynne Shotwell has said today they're going for the 33 engine static fire tomorrow.

Is this going to be streamed anywhere? Neither Everyday Astronaut or SpaceX seem to have a live feed in preparation (or I'm looking in the wrong place!).

https://www.youtube.com/watch?v=2kG4AbAcia0

[Hill92]

S6PNJ said:

Hill92 said:

Gwynne Shotwell has said today they're going for the 33 engine static fire tomorrow.

Is this going to be streamed anywhere? Neither Everyday Astronaut or SpaceX seem to have a live feed in preparation (or I'm looking in the wrong place!).

NASA Spaceflight have live feeds practically permanently:

https://www.youtube.com/live/2kG4AbAcia0

The NSF forums are also very useful for information alongside Reddit.

[S6PNJ]

Cheers Both!

[Legmaster]

I may be well late to the party, but from the Nasaspaceflight feed it looks like they are filling up Starship.

Is the static fire happening (potentially) or I have I missed a scrub notice?

[Russ35]

Legmaster said:

I may be well late to the party, but from the Nasaspaceflight feed it looks like they are filling up Starship.

Is the static fire happening (potentially) or I have I missed a scrub notice?

Currently loading to do a full 33 engine test.

[annodomini2]

2100 uk time estimated for SF

[Jackarmy100]

It’s pretty full by the looks of it (of oxygen at least)
Don’t think it’ll be long till they light it

[MartG]

Fuelled !

[Legmaster]

Thank you. It's looking quite good on the NSF channel. Hopefully we get a kaboom soon. Elon said somethin like "it may not go to plan, but it will be spectacular" I'm paraphrasing as I'm old I can't remember anything anymore...

[annodomini2]

SpaceX countdown held at 40s

[Leithen]

Cripes.

[Jackarmy100]

Well now!

[Grey_Area]

Bloody hell… that was something

[GiantCardboardPlato]

Bbbssssccccchhhhhhhh

[LivLL]

2 engines failed. Still spectacular.

[annodomini2]

LivLL said:

2 engines failed. Still spectacular.

1 was shutdown by the controllers before ignition, 1 shutdown during SF

https://twitter.com/elonmusk/status/16237939099599...

[LivLL]

Yep, 2 failed.