totm nov 2023 SpaceX Discussion Thread

[tater]

 

[Guest]

Geeze... they are really cramming those engines in...

imagine the noise @_@...

Edited July 22, 2019 by Guest

[mikegarrison]

So I guess that bit in the middle is the wabe, where the engines do gyre and gimble?

Just now, Dale Christopher said:

Geeze... they are really cramming those engines in...

Yeah. Makes me wonder, if one engine has an uncontained failure (ie. blows up), how many engines would they lose? It seems like "more engines = more redundancy", but for certain modes of failure more engines only means more opportunity to lose the whole ship.

I also worry a bit about there being no alternative to a propulsive landing. If you have some kind of Apollo 13 event, your Starship can't passively re-enter. Then what?

[Guest]

Lithobraking  XD

Edited July 23, 2019 by Guest

[CatastrophicFailure]

40 minutes ago, mikegarrison said:

Yeah. Makes me wonder, if one engine has an uncontained failure (ie. blows up), how many engines would they lose? It seems like "more engines = more redundancy", but for certain modes of failure more engines only means more opportunity to lose the whole ship.

No idea how they plan on Superheavy, but an early Falcon 9 did have one and still made orbit. IIRC the new octaweb is supposed to be even stronger and contain any failure. SH would likely be similar. 

42 minutes ago, mikegarrison said:

also worry a bit about there being no alternative to a propulsive landing. If you have some kind of Apollo 13 event, your Starship can't passively re-enter. Then what?

Send up a rescue ship.  

Rapid reusability is the end goal, here. Once that’s in play, sending an impromptu rescue within hours suddenly becomes plausible. 

[mikegarrison]

42 minutes ago, CatastrophicFailure said:

Send up a rescue ship.  

Rapid reusability is the end goal, here. Once that’s in play, sending an impromptu rescue within hours suddenly becomes plausible. 

And transfer everyone via EVA? I mean, yeah, that's what Jeb would do, but that seems pretty fraught in the real world.

We already know how Columbia turned out, with the whole "well, there's nothing we can do so let's hope for the best" thing. After Columbia they always supposedly had a rescue shuttle ready to go for every flight, but I never did know how they were going to get everybody from one shuttle to the other. They didn't carry an EVA suit for all the astronauts, did they?

[Turns out Wikipedia knows. The plan was to transfer the astronauts from the wounded shuttle to the ISS. Then return them with the rescue shuttle 40 days later. Before the ISS, they had considered using personal rescue devices that were essentially beach balls. The two EVA specialist would get into suits, everybody else would get into their beach balls, and then the EVA specialists would transfer the others from one shuttle to the other shuttle.]

42 minutes ago, CatastrophicFailure said:

an early Falcon 9 did have one and still made orbit

No, an early Falcon 9 had an engine shutdown. It didn't explode. I'm not so worried about a shutdown. What I'm wondering about it if a turbine disk goes and throws bits of the turbine all over the place. it's the same concern for when jet engines are placed close to each other.

Quote

“We know the engine did not explode because we continued to receive data from it,” SpaceX said in an Oct. 8 2012 press release. “Our review indicates that the fairing that protects the engine from aerodynamic loads ruptured due to the engine pressure release, and that none of Falcon 9’s other eight engines were impacted by this event.”

 

Edited July 23, 2019 by mikegarrison

[Guest]

14 minutes ago, mikegarrison said:

What I'm wondering about it if a turbine disk goes and throws bits of the turbine all over the place

Just look what happened to Crew Dragon, there was a fault in a valve and (I duno but,) it looked like they lost the entire capsule. 

[magnemoe]

1 hour ago, mikegarrison said:

So I guess that bit in the middle is the wabe, where the engines do gyre and gimble?

Yeah. Makes me wonder, if one engine has an uncontained failure (ie. blows up), how many engines would they lose? It seems like "more engines = more redundancy", but for certain modes of failure more engines only means more opportunity to lose the whole ship.

I also worry a bit about there being no alternative to a propulsive landing. If you have some kind of Apollo 13 event, your Starship can't passively re-enter. Then what?

The part who tend to blow up is the turbo pump. Falcon 9 is armored against this. An turbo pump RUD should not take out other engines. However you don't care about fragments penetrating skirt, only if they hit other engines. 

This is obviously harder on super heavy because multiple rings. 
6 engines in landing leg fairings indicate an legs / fins system like starship, might simply be an small strake who act as an leg pod, or it could be something who also act as an control surface.

[tater]

Note that the renders shown of engines are not official, just a guy.

[CatastrophicFailure]

28 minutes ago, mikegarrison said:

No, an early Falcon 9 had an engine shutdown. It didn't explode. I'm not so worried about a shutdown. What I'm wondering about it if a turbine disk goes and throws bits of the turbine all over the place. it's the same concern for when jet engines are placed close to each other.

I hadn’t heard this, but like @magnemoe said the newer Octaweb is designed to protect against a RUD... proliferating. Since they have experience, I’m sure SpaceX is considering that with SH too.

33 minutes ago, mikegarrison said:

but I never did know how they were going to get everybody from one shuttle to the other. They didn't carry an EVA suit for all the astronauts, did they?

You were right in the first count, STS-400 was still the contingency plan for the final Hubble servicing mission. 

The problem here is that two shuttles were never designed to dock. Again, knowing this, and their overall plans, I presume SpaceX will design Starships to be able to dock to each other. 

14 minutes ago, Dale Christopher said:

Just look what happened to Crew Dragon, there was a fault in a valve and (I duno but,) it looked like they lost the entire capsule. 

One reason why Starship will not be using hypergols.  At least not at that pressure. 

[Ultimate Steve]

1 minute ago, CatastrophicFailure said:

 

The problem here is that two shuttles were never designed to dock. Again, knowing this, and their overall plans, I presume SpaceX will design Starships to be able to dock to each other. 

If they intend to do anything beyond LEO, they sort of have to be able to dock to each other for refueling. Granted, it would be very difficult to transfer crew if the spacecraft are still docking butt to butt. However, if Starship is to go to any space station, present or future (they have said a bit about ISS docking) they need to be able to dock, so I would imagine they should. The initial prototypes probably won't have this, but I would definitely expect the crew versions to. I am fairly certain that a docking port can be made lighter than 20 spacesuits, and definitely lighter than 100 spacesuits.

[magnemoe]

12 minutes ago, Ultimate Steve said:

If they intend to do anything beyond LEO, they sort of have to be able to dock to each other for refueling. Granted, it would be very difficult to transfer crew if the spacecraft are still docking butt to butt. However, if Starship is to go to any space station, present or future (they have said a bit about ISS docking) they need to be able to dock, so I would imagine they should. The initial prototypes probably won't have this, but I would definitely expect the crew versions to. I am fairly certain that a docking port can be made lighter than 20 spacesuits, and definitely lighter than 100 spacesuits.

As I understand they will have an docking port in the air lock in the cargo bay. 
Guess it will pop out a bit for two starships to dock. 

[kerbiloid]

Spoiler

They can put pax into a transfer capsule and transfer it with canadarms.
Arthropoda do this.

Also make the landing legs stepping, and the landed Starship will be walking across the planet on "legs", taking things with "arms" and put them into the airlock "mouth".

Next step: the carbon hull made of chitin.

 

Edited July 23, 2019 by kerbiloid

[tater]

Crew version discussion (regarding details) should probably wait until there is one to actually look at, lol.

Orbital prototypes, least we can see those (which is pretty amazing).

[AVaughan]

For the initial crew version, I sort of expecting that they will need to include a capsule (ie something equivalent to a Dragon/Orion/Apollo capsule.  For the initial crew versions, I'm expecting max crew size of around 6 - 12).   That can serve as part of an emergency escape system during ascent/descent, and even as a re-entry capsule for a lunar return, if for some reason Starship has a serious anomaly.  

It will cut into payload capacity, but Starships payload capacity would still be large even carrying a built in escape capsule, and I'm not expecting that they can get NASA to man rate starship for Earth takeoff and landings without some sort of emergency escape system, at least not for the next few years.  The only alternative I can think of is either transfering crew after launch or docking and pushing a separately launched capsule. 

For a 50-100 passenger Mars version such an escape system would be less practical, but they could either transfer passengers after launch, (eg as part of the refueling flights), or maybe just not bother to get that version man rated by NASA.  (NASA is likely to insist on a man rated vehicle for any NASA contracts that are going to be carrying astronauts, but do SpaceX need a man rated vehicle for Mars colonists)? 

 

[Guest]

47 minutes ago, AVaughan said:

but do SpaceX need a man rated vehicle for Mars colonists)?

Not if they send women >_<

[Wjolcz]

10 hours ago, tater said:

 

My guess is the first artist is a dancer. Space 0G ballet will probably look quite spectacular.

Edited July 23, 2019 by Wjolcz

[Wjolcz]

1 hour ago, AVaughan said:

For a 50-100 passenger Mars version such an escape system would be less practical, but they could either transfer passengers after launch, (eg as part of the refueling flights), or maybe just not bother to get that version man rated by NASA.  (NASA is likely to insist on a man rated vehicle for any NASA contracts that are going to be carrying astronauts, but do SpaceX need a man rated vehicle for Mars colonists)? 

This is why I think it would be best to send colony ships in twos. Strap them together and you get to enjoy 1G for the whole trip. Something bad happened on one of them? Just stop the rotation, unthether and dock to transfer the crew to safety.

+The second ship is an extra fuel tank that can be ditched if you need to do a high ∆V burn for emergency reasons.

Edited July 23, 2019 by Wjolcz

[Guest]

It would be nice, and there’s already going to exist a nose hardpoint for stacking Starship onto the booster so you could easily nose to nose spin them with little to no alterations, however that hardpoint is almost certainly designed with lifting an unfueled Starship in 1G not ones with a substantial fuel load. But even so... some gravity is better than no gravity. 

With a little alteration I’m sure you could improve the whole process by building a winch and spool of cable directly into the nose, this would let you control the force imparted to the vehicles by simply winding the cables in or out, with little need for coordination of RCS thrusts between the two. 

The risks to the ships should be minimal... 

Edited July 23, 2019 by Guest

[kerbiloid]

10 hours ago, mikegarrison said:

It seems like "more engines = more redundancy", but for certain modes of failure more engines only means more opportunity to lose the whole ship.

Spoiler

 

[tater]

 

[sh1pman]

Who will win? My bet is on team SpaceX. They’re already testing the lander prototype!

[Wjolcz]

38 minutes ago, sh1pman said:

Who will win? My bet is on team SpaceX. They’re already testing the lander prototype!

We all will.

[magnemoe]

22 hours ago, mikegarrison said:

So I guess that bit in the middle is the wabe, where the engines do gyre and gimble?

Yeah. Makes me wonder, if one engine has an uncontained failure (ie. blows up), how many engines would they lose? It seems like "more engines = more redundancy", but for certain modes of failure more engines only means more opportunity to lose the whole ship.

I also worry a bit about there being no alternative to a propulsive landing. If you have some kind of Apollo 13 event, your Starship can't passively re-enter. Then what?

yes assume the core 7 engines is the one with gimbal. As for the engine placement its 31 inside the 9 meter body with the outer ring extend a bit past 9 meter, for 37 this require 6 engines out below the landing legs housing. 
Loss of engines or turbo pumps blowing up they can probably handle. Stainless is excellent armor and you can slate it a lot. 

Now structural fails, or fails in plumbing like the LOX start leaking into the methane tank or secondary system fails like pressurized oxygen or methane tanks and yes add the control systems and software issues. 
Apollo 13 would be an loss of craft and crew outside of the Apollo craft in transit from earth to moon. 
For an single stage LEO-Moon-land it would also be an catastrophically mission fail unless an very high degree of redundancy. 

Belt, two pairs of suspenders, an process to verify that the pant would stay on even if all fail, then add an coverall and an long coat and you suffer overheating  

And yes the only issue I see with starship is the lack of some sort of an LES.

 

[mikegarrison]

2 minutes ago, magnemoe said:

Loss of engines or turbo pumps blowing up they can probably handle. Stainless is excellent armor and you can slate it a lot.

I think you underestimate the amount of energy released if a disk fails. It's usually treated for survivability design purposes as an infinite energy event.