totm nov 2023 SpaceX Discussion Thread

[Beccab]

Official inspiration 4 logo:

Official Dragon with cupola render:

And last but not least, the Inspiration 4 team flying in front of their own Falcon 9:


Edit: Oh, and cool pic of Starlink 2-1 mission too

 

Edited September 14, 2021 by Beccab

[Ricktoberfest]

I think people over estimate the ability to hover.  The ability is there but I don’t think we’ll see it used. We’ve all seen the landings of the prototypes. They don’t hover. Why? Because it takes too much fuel.  (Yes I know there’s a weight difference between the prototype and an actual rocket - doesn’t change the fuel requirements).   The only prototype that hovered was hopper, and that’s all it did.  I doubt they can switch from a suicide burn into a hover at the last seconds. It has to be planned ahead of time. 
 

blue origin can get away with hovering because their payload is light and their goal is to get just barely into space.  Also it’s built into the flight profile. 

[CatastrophicFailure]

5 minutes ago, Ricktoberfest said:

I think people over estimate the ability to hover.  The ability is there but I don’t think we’ll see it used. We’ve all seen the landings of the prototypes. They don’t hover. Why? Because it takes too much fuel.  (Yes I know there’s a weight difference between the prototype and an actual rocket - doesn’t change the fuel requirements).   The only prototype that hovered was hopper, and that’s all it did.  I doubt they can switch from a suicide burn into a hover at the last seconds. It has to be planned ahead of time. 
 

blue origin can get away with hovering because their payload is light and their goal is to get just barely into space.  Also it’s built into the flight profile. 

It’s not so much that it will hover, it’s that it can… in contrast to Falcon 9 which cannot. This means that they have full control of descent speed right down to zero m/s, which will allow much more precise maneuvers than F9’s suicide burn, even if SH is actually still moving the entire time. 

[tater]

 

44 minutes ago, mikegarrison said:

IMO, they are being driven by what I think is an unreasonable requirement. The vision is to land, refuel and take off again. It's hard to imagine they really have a need for that kind of cadence, even considering the need for multiple refueling flights in close succession. But that's what seems to be driving them to the "land on the launchpad" solution.

Aggressive design goals are fine -- you'll never hit goals you don't aim for -- but if they compromise meeting the more basic requirements, they can turn into problems.

The land/repeat thing is driven partially by kooky Mars goals. Many of us here agree they are kooky—but that is literally why they exist, so it has to be taken into account.

1000 ships per synod to Mars (LOL).

Again, I'm with my friend who thinks the colony should be named "New Donner."

The other factor is mass to LEO, and minimizing refilling trips. We know what the RTLS payload losses for F9 are, they are ~40% for launches with a boostback burn and RTLS, and all SH launches will be RTLS with very similar staging, etc. So presumably that's something they are optimizing for.

If the grid fins could hold the thing... honestly, the F9 landing accuracy makes a grid fin catch look not that bad. Those 2 tiny knobs, though? Yeesh.

[Ricktoberfest]

24 minutes ago, CatastrophicFailure said:

It’s not so much that it will hover, it’s that it can… in contrast to Falcon 9 which cannot. This means that they have full control of descent speed right down to zero m/s, which will allow much more precise maneuvers than F9’s suicide burn, even if SH is actually still moving the entire time. 

Yes but I doubt they could switch from one to the other mid burn. Either they plan to hover or they plan not to.  They’re not gonna bring down extra fuel if they don’t have to.  

if they could hover to make themselves more accurate I would have expected something of the sort during the initial testing. They definitely  landed the prototypes off center ( I think the first one even had a leg off the pad). They also had all the fuel they needed to hover if they chose to. 

Edited September 14, 2021 by Ricktoberfest
Typo

[CatastrophicFailure]

15 minutes ago, Ricktoberfest said:

Yes but I doubt they could switch from one to the other mid burn. Either they plan to hover or they plan not to.  They’re not gonna bring down extra fuel if they don’t have to.  

if they could hover to make themselves more accurate I would have expected something of the sort during the initial testing. They definitely  landed the prototypes off center ( I think the first one even had a leg off the pad). They also had all the fuel they needed to hover if they chose to. 

I think you're still missing the point. There is no either/or here, landing SH will be like a constant, smooth slow to a stop in your car, unlike Falcon, which slams on the brakes at the very last moment. SH most likely will not hover, but it can, that's the point, it has enough engine control to do so, so if it can do that, it can also have infinite control of its descent speed from TV to zero. It can slow down a lot, or just a little, in order to gain time to make other adjustments as to exactly where it ends up. 

The prototypes were just that: prototypes. Pinpoint landing was not part of their mission profile, just "good enough" to reach the concrete pad. The fact that they touched down, tilted, on a single off-center engine doesn't help with precision, either. 

[JoeSchmuckatelli]

So -- aside from being jealous that the Inspiration 4 winners get a trip to space... I have to be jealous they all got to fly fighter jets?

...

Not that it would matter; I'm 'overqualified'

Once again - the short people are showing their prejudice against us tall guys.  Damn engineers don't seem to recognize that approx. 2% of the population are over 6'6".  (Proven in Coach on EVERY AIRLINE and virtually every car backseat).

Remember Shakespeare's 'let's start with the lawyers' line?  Well for us tall people it's "There's those short engineers -- GET 'EM!) 

[MKI]

9 minutes ago, JoeSchmuckatelli said:

Once again - the short people are showing their prejudice against us tall guys.  Damn engineers don't seem to recognize that approx. 2% of the population are over 6'6".  (Proven in Coach on EVERY AIRLINE and virtually every car backseat).

I know some one who worked in aerospace and there was bonuses per pound for whoever could think of ideas to save weight, as the design was too heavy. 

One idea was to only have "little people" fly the planes, which would save a lot of weight in multiple categories.  (Not sure of "little people" is offensive or not, I don't mean to offend, I just don't know what the preferred label is)

  

56 minutes ago, Ricktoberfest said:

if they could hover to make themselves more accurate I would have expected something of the sort during the initial testing. They definitely  landed the prototypes off center ( I think the first one even had a leg off the pad). They also had all the fuel they needed to hover if they chose to. 

SH has yet to be tested, the Starship tests are more verifying the ability to belly flop+land. 

Yes they use the same engine, but previous tests are focusing on testing other parts of the system (landing+belly flopping Starship) while testing engine performance. SH can't fly on its own and requires more engines to test, so Starship must be further along before getting to SH as its higher risk and harder to iterate on.

 

The launch cadence needs to be extremely high to support orbital refueling, which is the only way anything gets anywhere. 

Edited September 14, 2021 by MKI

[Beccab]

Official SpaceX pre-flight Q&A with the crew, live in about two hours and a half

[RealKerbal3x]

2 hours ago, tater said:

1000 ships per synod to Mars (LOL).

I believe the 1000 ships figure was the total for building and maintaining the colony over a couple of decades (until it's self sufficient). It's much more likely to be 2 or 3 ships max per transfer window. 1000 ships for every window would probably require a higher launch cadence than they're ever planning to have.

2 hours ago, tater said:

If the grid fins could hold the thing... honestly, the F9 landing accuracy makes a grid fin catch look not that bad. Those 2 tiny knobs, though? Yeesh.

The grid fins are likely the backup option in case they miss the load points. They're probably strong enough to take the load of an empty booster, considering the aerodynamic forces they already have to survive. I also recall Elon mentioning that circling back to just directly using the grid fins to catch is a possibility.

Edited September 14, 2021 by RealKerbal3x
d'oh, left sentence unfinished

[zolotiyeruki]

3 hours ago, mikegarrison said:

IMO, they are being driven by what I think is an unreasonable requirement. The vision is to land, refuel and take off again. It's hard to imagine they really have a need for that kind of cadence, even considering the need for multiple refueling flights in close succession. But that's what seems to be driving them to the "land on the launchpad" solution.

Aggressive design goals are fine -- you'll never hit goals you don't aim for -- but if they compromise meeting the more basic requirements, they can turn into problems.

Even if SpaceX don't end up launching a given SH multiple times per day, there are *definitely* advantages to designing the whole system (SH + tower and everything with it) for rapid reuse.  Lots of time (and therefore money) saved by not having to haul it back to shore, offload it, tip it over, transport it to the rocket factory, refurbish it, integrate it, truck it out to the launch pad, tip it up, etc.  The new process, assuming it works, is "stick the booster back on the pad, stack SS on top, refuel, push the big red button."  That certainly fits with the "best part is no part" ethos.

[SOXBLOX]

2 hours ago, JoeSchmuckatelli said:

So -- aside from being jealous that the Inspiration 4 winners get a trip to space... I have to be jealous they all got to fly fighter jets?

...

Not that it would matter; I'm 'overqualified'

Once again - the short people are showing their prejudice against us tall guys.  Damn engineers don't seem to recognize that approx. 2% of the population are over 6'6".  (Proven in Coach on EVERY AIRLINE and virtually every car backseat).

Remember Shakespeare's 'let's start with the lawyers' line?  Well for us tall people it's "There's those short engineers -- GET 'EM!) 

I know what you mean! I'm only 6'5", though, but I still have to fold myself into the little Embraer regional jets. Last time I flew on one of those, my head hit the cabin roof. Not the overhead compartments, but the aisle. 

[tater]

 

[tater]

 

[magnemoe]

14 hours ago, RealKerbal3x said:

The grid fins are likely the backup option in case they miss the load points. They're probably strong enough to take the load of an empty booster, considering the aerodynamic forces they already have to survive. I also recall Elon mentioning that circling back to just directly using the grid fins to catch is a possibility.

Agree, downside of catching the fins is that you will damage the edges on the back of them. 

[AVaughan]

22 minutes ago, magnemoe said:

Agree, downside of catching the fins is that you will damage the edges on the back of them. 

You probably also need to ensure that they are horizontal rather than rotated, otherwise you risk damaging the rotation mechanism.

[Beccab]

4 minutes ago, AVaughan said:

You probably also need to ensure that they are horizontal rather than rotated, otherwise you risk damaging the rotation mechanism.

I believe they should be nearly horizontal anyway when it reaches the pad, even if it doesn't have much effect it still would screw with aerodynamics a bit without a reason

[Reactordrone]

Inspiration 4 will bring us to 14 people in orbit, with seven on the ISS, three on the CSS and four free flying on Dragon. There have been more people in space with the suborbital flights but not more in orbit.

[Beccab]

3 minutes ago, Reactordrone said:

Inspiration 4 will bring us to 14 people in orbit, with seven on the ISS, three on the CSS and four free flying on Dragon. There have been more people in space with the suborbital flights but not more in orbit.

About this stuff, there is this handy image made by someone on twitter

[kerbiloid]

17 hours ago, Beccab said:

An allusion to the Time Masters, 1982 ?

Spoiler

 

 

[DDE]

16 hours ago, JoeSchmuckatelli said:

Not that it would matter; I'm 'overqualified'

Once again - the short people are showing their prejudice against us tall guys.  Damn engineers don't seem to recognize that approx. 2% of the population are over 6'6".  (Proven in Coach on EVERY AIRLINE and virtually every car backseat).

Remember Shakespeare's 'let's start with the lawyers' line?  Well for us tall people it's "There's those short engineers -- GET 'EM!) 

 

20 hours ago, JoeSchmuckatelli said:

The whole 'catch a rocket' thing is pretty bonkers.  Especially without landing legs.  That's just plain nuts.

....aaaaand yet, if anyone can do it (even if it takes a few tries) SX just might be the group to pull it off.

A concern I voiced maybe, what, two years back was that Musk has built up such momentum that for him to fail may spell the doom for the entire NewSpace movement.

[Nothalogh]

14 hours ago, SOXBLOX said:

Embraer regional jets

I once flew on one of those, the experience made me wish I was riding on the outside of a Tupolev.

Bombardier, on the other hand, makes rock solid regional jets.

[tater]

Gonna have long coverage for I4. Launch NET 11 hours, coverage live in 6.

 

Edited September 15, 2021 by tater

[tater]

 

 

 

[Beccab]

While the preparation for the launch continues (3 hours till the stream starts, 10 hours till the window opens), it appears that B5 started to grow! While the cams don't allow any clear view of it, people on reddit reported that very likely the B5 LOX tank that was spotted has been put on one of the quad barrels while another quad barrel was brought in the high bay for stacking in the next days

Edit: usual insider just reported that the road closure on friday (secondary dates monday and tuesday) is for S20 to do ambient and N2 WDR!

Edited September 15, 2021 by Beccab