totm nov 2023 SpaceX Discussion Thread

[PakledHostage]

8 minutes ago, Nightfury said:

They showed it just before landing

Sure, but that's not the interesting part.

[sh1pman]

I feel like I’m slowly becoming a launch addict.

[regex]

Well done!

[magnemoe]

1 hour ago, sevenperforce said:

Yeah, just a touch of off-plane inclination will help keep it out of intercepts, but it will still cross Earth orbit now and then. 

But computing a trajectory which has no Earth encounters for millions of years is not that hard to do. Not when you're SpaceX. Just need a fast computer.

HYPE TRAAAAAAAIN

Its actually pretty hard if it come close to planets. We can not predict Halleys komet a tousand year into the future, think it breaks down after 4-500 years even if it don't come close to anything the error margins build up and become to large. Yes an comet is a bit hard as small change will change Ap a lot generating an huge error on next pass and this build up fast.

[sevenperforce]

36 minutes ago, magnemoe said:

Its actually pretty hard if it come close to planets. We can not predict Halleys komet a tousand year into the future, think it breaks down after 4-500 years even if it don't come close to anything the error margins build up and become to large. Yes an comet is a bit hard as small change will change Ap a lot generating an huge error on next pass and this build up fast.

As I understand it, the trickiest part of dealing with comet trajectories is that comets lose mass and experience significant braking at perihelion, which really screws up estimates. For something with a perihelion at 1 AU, it should be much more predictable. 

[CatastrophicFailure]

Also guys, the Roadster's course doesn't need to avoid Mars (or Earth) for millions of years... only a couple hundred, maybe three... if there's risk of a close pass after that, it'll either be a trivial thing to go move it... or we won't be here to worry about it in the first place. 

[Ultimate Steve]

1 hour ago, sh1pman said:

I feel like I’m slowly becoming a launch addict.

I already was! I was going through severe withdrawl this month so far, delays, aborts after engine ignition, top secret launches, normal launches during school so I can't watch them...

I have yet to see a live launch this month.  Let's hope for Electron tonight!

[DAL59]

2 hours ago, Nightfury said:

Do NASA has a covarage for the arrival of Dragon ?

Yes, go to the nasa website, click Media, then tune in to NASA TV.  

[tater]

5 minutes ago, DAL59 said:

Yes, go to the nasa website, click Media, then tune in to NASA TV.  

On Sunday.

4:30 am EST.

[.50calBMG]

On 12/5/2017 at 3:42 AM, NSEP said:

It looks like it has landing legs? Is this going to land on its first flight too?

Forgive me for going back in time, but is it just me or do those grid fins on the side boosters look like the titanium batman fins to anyone else?

Coming back to today's launch, there was a cool shot of sooty coming back in just after reentering the atmosphere where you could see bits of paint flaking off the grid fins.

Edited December 15, 2017 by .50calBMG

[tater]

Can't tell from that pic, but nothing will be coming down really hot on FH test flight, I think they'd use up the fins they have.

[sevenperforce]

22 minutes ago, .50calBMG said:

Forgive me for going back in time, but is it just me or do those grid fins on the side boosters look like the titanium batman fins to anyone else?

Coming back to today's launch, there was a cool shot of sooty coming back in just after reentering the atmosphere where you could see bits of paint flaking off the grid fins.

 

3 minutes ago, tater said:

Can't tell from that pic, but nothing will be coming down really hot on FH test flight, I think they'd use up the fins they have.

I'm going to go out on a limb and say those ARE titanium grid fins, at least on the side boosters.

[tater]

^^^you guys have better eyes than I do, lol.

[sevenperforce]

2 minutes ago, tater said:

^^^you guys have better eyes than I do, lol.

They are just much darker than the underlying paint.

Oddly, I don't see the same for the core. Doesn't make much sense to use titanium fins on the lower-stress side boosters and aluminum ones on the hot-entry core...but idk. Maybe they are running short on aluminum grid fins and so they decided to put their last four on the core because it has the lowest chance of recovery. Or maybe they just hadn't installed grid fins on the core booster when this screengrab was caught.

[.50calBMG]

I ask because the titanium boosters had the curved edge, but yet if you look at them, specifically the one on the right side of the right booster, it seems like it has a flat edge. maybe they have a cover on them, but I don't think I've seen that on any of the other first stages they've had pictures of in the hangar

[StrandedonEarth]

Awesome!

[regex]

Have we talked about the Made In Space payload yet? Fiber optics test-bed?

[PB666]

1 hour ago, CatastrophicFailure said:

Also guys, the Roadster's course doesn't need to avoid Mars (or Earth) for millions of years... only a couple hundred, maybe three... if there's risk of a close pass after that, it'll either be a trivial thing to go move it... or we won't be here to worry about it in the first place. 

It could be thrown from our system.

Could you imagine the shock of some exosolar space race exploring low orbit  have a red sports car go flying by them in space at 30 km/sec.

[CatastrophicFailure]

3 minutes ago, PB666 said:

It could be thrown from our system.

Could you imagine the shock of some exosolar space race exploring low orbit  have a red sports car go flying by them in space at 30 km/sec.

Heh, I think it’s more likely our own descendants will find it. Ages pass, memory turns to legend, legend fades to myth, and even myth is long forgotten...

... and we’ve got four literal Wheels of Time to confuse the hell out of some future humans. 

[regex]

I hope the paint stands up for more than a year.

[monophonic]

58 minutes ago, sevenperforce said:

Oddly, I don't see the same for the core. Doesn't make much sense to use titanium fins on the lower-stress side boosters and aluminum ones on the hot-entry core...but idk.

Actually I think it would make perfect sense. Since the titanium fins are reusable, they benefit from reduced stress with increased service life. But the aluminum fins are toast even after the less stressful re-entry, so no point in pampering them.

[sevenperforce]

9 minutes ago, monophonic said:

Actually I think it would make perfect sense. Since the titanium fins are reusable, they benefit from reduced stress with increased service life. But the aluminum fins are toast even after the less stressful re-entry, so no point in pampering them.

IIRC, aluminum fins can be repainted and reused after RTLS landings but not after ASDS landings. The highest-energy ASDS landings burn up the aluminum grid fins so badly that they may start to lose control authority. 

Titanium grid fins have more control surface area and are thus better for all flights, but particularly for high-energy flights because they give the booster an enhanced glide ratio so it can use less propellant for guidance. You're slightly less likely to lose a booster if it has titanium fins than if it has aluminum ones.

[sevenperforce]

Loving pics like these from today's launch:

Looking longingly at the old Falcon Heavy animation. All the official SpaceX imagery still has the black landing legs. Any word on whether the Block V legs will have special TPS or something similar, or will they be white too?

[mikegarrison]

That was a pretty nifty video. I particularly liked that they zoomed in on the rocket and you could actually see the separation, flip and boostback from the ground. Also it's nice to see so much of the return plummet.

It does make me wonder how they convinced people to let them do it, though. Just a slight mistake and they could have that rocket come in at supersonic speeds right through the roof of the VAB or something.

[Ultimate Steve]

19 minutes ago, mikegarrison said:

It does make me wonder how they convinced people to let them do it, though. Just a slight mistake and they could have that rocket come in at supersonic speeds right through the roof of the VAB or something.

Experience. By the time they got the licence to RTLS, they had tested landing at a fixed spot of ocean a few times, tried barge landings, and had done grasshopper/F9Rdev1 tests. With the exception of the final flight of F9Rdev1, one of the first ocean landing attempts where they spun out of control, and CRS-7, all of those tests landed or crashed at a subsonic velocity within a few dozen meters of the target location. F9Rdev1 and CRS-7 had problems not related to landing, and that first ocean landing was the first attempt. Every other attempt hit the target.

Meaning that there was an incredibly low chance of them hitting anything other than LZ-1 during an RTLS.