totm nov 2023 SpaceX Discussion Thread

[tater]

White room closeout crew for Shuttle looks like it was 7 people. The "ice team" that did final vehicle inspection looks like it was 4 guys. So 11 people for 2.5 hours, then the X astronauts.

[sevenperforce]

17 minutes ago, tater said:

Prop loading on F9 begins at ~T - 1:10.

It looks like Shuttle had vehicle crew, and associated workers on the pad for at least 5.5 hours, or which ~3 hours were just the vehicle crew.

So 2.5 hours with many people, then 3 hours with 7 people on the pad with no plausible escape from any catastrophic failure, vs 70 minutes with the Dragon crew on the pad, with a LES capable of mitigating most any massive failure.

 

Seems like a no-brainer.

[mikegarrison]

3 hours ago, sevenperforce said:

Really old news.

I understand it's been discussed here before. But my reason for posting it is a) it's still an issue, and b) it's now being discussed in the general media market, not the specialized space news forums.

3 hours ago, sevenperforce said:

I don't understand why propellant loading while the astronauts are on the pad is more dangerous than propellant loading before the astronauts on the pad.

Well, the one time a Falcon did blow up on the pad is when they were loading the propellant, so maybe NASA has a point here. I would guess that there is more that can go wrong when transferring tonnes of LOx than when it's just sitting there in the tank.

The argument that they can use the LES is valid, but it ignores basic safety protocol. You try to put as many links of the safety chain as possible between you and disaster at all times, rather than just relying on the last one to cover you.

2 hours ago, YNM said:

How long is the propellant loading ?

I know that I presume most (if not all) of the time, crew goes in before propellant loading, but perhaps, somehow SpX is a bit longer ?

No, actually on almost every rocket the propellant is loaded first, then the crew goes in.

Edited May 7, 2018 by mikegarrison

[mikegarrison]

The thing is, as long as SpaceX is using "densified" fuel, they may not have any choice in the matter. It's not matter of whether it is riskier to load the fuel with the crew on board or to load the crew with the fuel on board. They pretty much have to load the fuel with the crew on board. And I would guess that NASA has some solid data that shows that the fueling process is more dangerous than simply being around an already-fueled rocket.

It's going to be an issue that NASA and SpaceX are going to just have to work through.

[Wjolcz]

It just occured to me that I know near to nothing about shuttle's LES. And its initial flight was manned. The LES there consisted of seats shooting out of the cockpit and astronauts' parachutes, iirc?

[sevenperforce]

34 minutes ago, Wjolcz said:

It just occured to me that I know near to nothing about shuttle's LES. And its initial flight was manned. The LES there consisted of seats shooting out of the cockpit and astronauts' parachutes, iirc?

The very first Shuttle flight, on Columbia, had ejection seats for the two-man crew. The utility of these seats was in dispute; an ejection while the solid boosters were still firing would almost certainly have left the astronauts inside the SRB engine plume or too close for comfort. Ejection after the solids were jettisoned was likely too high for survival. There was no provision for pad abort.

Flights after STS-1 had no provision for catastrophic abort whatsoever. The ejection seats were removed because there weren't enough seats close to windows for everyone to have an ejection option.

[YNM]

3 hours ago, mikegarrison said:

No, actually on almost every rocket the propellant is loaded first, then the crew goes in.

Oh. Including Soyuz ?

[Bill Phil]

Columbia's first four flights had the ejection seats.

There was also an option for RTLS, other landing sights, and abort to orbit, provided failure wasn't a LOCV event.

[mikegarrison]

1 hour ago, sevenperforce said:

Flights after STS-1 had no provision for catastrophic abort whatsoever. The ejection seats were removed because there weren't enough seats close to windows for everyone to have an ejection option.

That's not really entirely true. They did have provisions for certain types of abort, namely those that would leave the orbiter intact but unable to achieve orbit. In that case they had various emergency landing strips scattered about the path that the orbiter might be following.

[tater]

While they practiced some abort modes in simulation, in real life it was extremely unlikely to ever have been possible.

[Ultimate Steve]

Although on one of the shuttle missions, an abort to orbit was actually used.

[StupidAndy]

9 minutes ago, Ultimate Steve said:

Although on one of the shuttle missions, an abort to orbit was actually used.

do you know the mission? always wondered how that worked

[tater]

5 minutes ago, StupidAndy said:

do you know the mission? always wondered how that worked

https://en.wikipedia.org/wiki/STS-51-F

[StrandedonEarth]

47 minutes ago, Ultimate Steve said:

Although on one of the shuttle missions, an abort to orbit was actually used.

I remember that. Basically one of the most benign failures that could happen. The center engine was automatically shut down due to a sensor reading. It was late enough in the ascent that it could simply continue to orbit, although it may not have gone as high as originally planned. I'm typing this from my memory of watching that launch, without reading the link tater posted. 

If the engine had shut down earlier, things would have gotten "interesting." I suspect the gimbal could have compensated if one of the other engines had shut down that late instead.

Now excuse me while I read that link... Edit: Yup, pretty close to what I remembered, forgot that it was the sensors failing, although I did seem to recall it was a temp sensor. Of course, that link also gave more info than what the news reported at that time

Edited May 8, 2018 by StrandedonEarth

[sevenperforce]

11 hours ago, YNM said:

Oh. Including Soyuz ?

Yeah, they open the fairing hatch and the Soyuz capsule hatch on the pad, when the rocket is full of propellant. Support staff are in and out of the hatch at this time, securing them. Any catastrophic problem during this phase would be LOC because there's no way to get away from the booster.

10 hours ago, Bill Phil said:

Columbia's first four flights had the ejection seats.

Good catch.

Quote

There was also an option for RTLS, other landing sights, and abort to orbit, provided failure wasn't a LOCV event.

Well, presumably there's never going to be an abort in a LOC event.

10 hours ago, mikegarrison said:

12 hours ago, sevenperforce said:

Flights after [ejection seats were removed] had no provision for catastrophic abort whatsoever. The ejection seats were removed because there weren't enough seats close to windows for everyone to have an ejection option.

That's not really entirely true. They did have provisions for certain types of abort, namely those that would leave the orbiter intact but unable to achieve orbit. In that case they had various emergency landing strips scattered about the path that the orbiter might be following.

Hence why I said "catastrophic" abort. Any structural failure or even a thrust imbalance between the SRBs was LOCV. No catastrophic abort provision.

8 hours ago, StrandedonEarth said:

I remember that. Basically one of the most benign failures that could happen. The center engine was automatically shut down due to a sensor reading. It was late enough in the ascent that it could simply continue to orbit, although it may not have gone as high as originally planned. I'm typing this from my memory of watching that launch, without reading the link tater posted. 

If the engine had shut down earlier, things would have gotten "interesting." I suspect the gimbal could have compensated if one of the other engines had shut down that late instead.

IIRC, the parallel sensor on another engine was also faulty and was getting ready to shut it down as well. If that engine had shut down, the orbiter wouldn't have had enough thrust to survive through SRB jettison.

[tater]

Regarding crew flights, what is the added capability due to deep chilled props on F9? Crew Dragon with cargo is ~10 tonnes. I wonder if F9b5 could send it to ISS without deep chilling the props, and still have margin to land the booster?

Clearly they want to just do the same thing every launch, but I wonder if it's even required for these few crew missions.

[Ultimate Steve]

14 minutes ago, tater said:

Regarding crew flights, what is the added capability due to deep chilled props on F9? Crew Dragon with cargo is ~10 tonnes. I wonder if F9b5 could send it to ISS without deep chilling the props, and still have margin to land the booster?

Clearly they want to just do the same thing every launch, but I wonder if it's even required for these few crew missions.

That largely depends on if the Merlins can still operate with the less dense propellant.

[sevenperforce]

34 minutes ago, Ultimate Steve said:

That largely depends on if the Merlins can still operate with the less dense propellant.

They can.

[tater]

 

[tater]

 

[sevenperforce]

1 hour ago, tater said:

 

HOLY MOTHER OF

[tater]

6 minutes ago, sevenperforce said:

HOLY MOTHER OF

Right?

[Ultimate Steve]

6 minutes ago, sevenperforce said:

HOLY MOTHER OF

Off topic, this made me wonder who Jeb's mom was. Do you think she tragically died in a rocketry accident or something?

Serious: This is excellent news, the aspirational timeline has moved *gasp* LEFT!

[CatastrophicFailure]

5 minutes ago, Ultimate Steve said:

Serious: This is excellent news, the aspirational timeline has moved *gasp* LEFT!

Hello? Hello? Information? Quick, what’s the temperature in hell?!

Just seeing that beast leave the hangar the first time will be an experience!

[Ultimate Steve]

4 minutes ago, CatastrophicFailure said:



Just seeing that beast leave the hangar the first time will be an experience!

If you want a bit of a teaser, the BFS is within a few feet in all dimensions of the shuttle's external tank.