totm nov 2023 SpaceX Discussion Thread

[tater]

 

[insert_name]

The Paz launch will carry two prototype SATs for starlink

https://www.nasaspaceflight.com/2018/02/falcon-9-static-fire-vandenberg-paz-starlink/

[Ultimate Steve]

Hmm... The satellite adapter can be called a dispenser... So it's a Paz dispenser... So it's a Pez Dispenser...

[Kerbinchaser]

RIP Falcon Heavy Center Core.

 

Died after hitting the surface at 300 MPH.

[sevenperforce]

8 minutes ago, Lo Var Lachland said:

RIP Falcon Heavy Center Core.

Died after hitting the surface at 300 MPH.

Yes, that's what Elon said about an hour after the launch.

[Kerbinchaser]

Just now, sevenperforce said:

Yes, that's what Elon said about an hour after the launch.

Owwwwie.   

[DerekL1963]

On 2/8/2018 at 6:49 PM, Confused Scientist said:

That's understating the reliability, since the Falcon 9 is also the first rocket since the Saturn V to have a full engine-out capability on the first stage.

Which sure sounds impressive.  But it's not actually all that impressive once you're cognizant of the facts....  which is that with few exceptions, modern engines fail very rarely.

Falcon 9 has nine engines because when the Falcon 1 flopped in the market and SpaceX was nearly broke - they didn't have the budget or the time to develop a proper engine.  (Which also resulted in Falcon 9 initially being on the underpowered side given market trends.)   All that guff about engine out capability is taking water and adding fake lemon flavor to turn it into lemonade and marketing copy.

[KSK]

13 hours ago, tater said:

 

Part of me is hoping that tumble is primarily in yaw. The idea of Starman pulling Space Donuts for a billion years amuses me.

[Elthy]

Isnt that stuff that belongs into the Mars colonization thread until SpaceX actualy says something about how they plan to do it? For now everything is just speculation...

[tater]

 

[sh1pman]

Ok, this is actually interesting:

 

[sevenperforce]

20 minutes ago, tater said:

 

I'M LOVING IT

Also, wow, the CEO quotes the price for an expendable launch. Finally, some datapoints!

Per this, a three-core-recovery Falcon Heavy runs $90M, while a recoverable Falcon 9 runs $62M. The price difference between a recoverable and expendable FH is thus $60, or $20 million per core. I would thus predict the cost of an expendable Falcon 9 at around $92M, then, all things being equal.

9 minutes ago, sh1pman said:

Ok, this is actually interesting:

 

I say very low possibility that they would actually stretch the upper stage. But this is the first confirmation of Fairing 2! Larger-diameter and presumably rapidly recoverable.

[Rakaydos]

4 minutes ago, sevenperforce said:

I say very low possibility that they would actually stretch the upper stage. But this is the first confirmation of Fairing 2! Larger-diameter and presumably rapidly recoverable.

At least 2nd mention from elon- the post Heavy press conference mentioned fairing recovery, and Fairing 2 is the one they really want back, but they've been having trouble with the fairing displacing so much air that it fouls the parachutes in flight.

[mikegarrison]

41 minutes ago, Elthy said:

Isnt that stuff that belongs into the Mars colonization thread until SpaceX actualy says something about how they plan to do it? For now everything is just speculation...

Well, I believe the link was that SpaceX uses GPS to control their landings, so the question was how they would do that if landing on Mars.

[sevenperforce]

11 minutes ago, Rakaydos said:

At least 2nd mention from elon- the post Heavy press conference mentioned fairing recovery, and Fairing 2 is the one they really want back, but they've been having trouble with the fairing displacing so much air that it fouls the parachutes in flight.

Oh, interesting.

Another tweet:

DATA GLORIOUS DATA

Does anyone have a guess as to what he means by performance? Does he mean that landing the side boosters and expending the core can lift a payload to a specified orbit 90% the size of what a fully-expended FH can do?

9 minutes ago, mikegarrison said:

Well, I believe the link was that SpaceX uses GPS to control their landings, so the question was how they would do that if landing on Mars.

GPS for landing pad accuracy; radar for the actual landing. 

[CatastrophicFailure]

Interesting choice of name, given the totality or things. I wonder what kind of numbers they could get from a FH with dual drone ship booster recovery and expended core?

Aaaaaaand question answered just above.  Thanks for the prescience, @sevenperforce. Out of likes as usual. 

Edited February 12, 2018 by CatastrophicFailure

[sh1pman]

I like this relaxed attitude towards rocket failures 

[CatastrophicFailure]

7 minutes ago, sh1pman said:

I like this relaxed attitude towards rocket failures 

Given the pucker factor that was floating around the place at T-0, to have everything go off so well except for one little hiccup with an easily recognizable and correctable cause, I’d expect nothing less. 

[sevenperforce]

25 minutes ago, sh1pman said:

I like this relaxed attitude towards rocket failures 

What a kidder.

[PB666]

1 hour ago, tater said:

 

I would draw your attention to the first post in the thread, because this rely's on a performances of RL10s at such a thrust that cosine losses are minimal.

Quote

Doug Ellison‏ @doug_ellison Feb 2 I’ve got to do a deep dive into the launch requirements of mission designs beyond LEO and compare F9 Arlas V 401, 551, FHeavy and FHeavy Expendable. I think a lot of people will be VERY surprised. Specific Impulse on the upper stage is everything.

How much are the customers willing to pay for an a high efficiency engine(s) that is only useful a few 1000 dV short of V_orbital that are hard to produce, expensive and currently in short supply. The replacement that would have been useful for such S2 staging to GTO for large payloads . . . .the F-2X was mothballed . . . .so . . . . . . . . .

Proof of the pudding is in the eating, while they list 19,200 PL to GTO, their prices (551) are $153,000,000 for 8900 to GTO.  SpaceX offers 14,200 to GTO (fully expendable) but 8,000 kT to GT0, they charge  $90,000,000 M
To arrive at 62KT in LEO you would need 4@ATLAs V 551 = $600 million. So they are only 60% more expensive to GTO and 700% more expensive to LEO . . . . . . . .

 

[sevenperforce]

6 minutes ago, DAL59 said:

You can just take the hydrogen with you, every kg of h2 can be used to produce several kgs of methane and oxygen.  You can also get water from the 100% humidity air.

Hydrogen is very fluffy. Also, the atmosphere is so low in water vapor that you're looking at thousands of cubic meters of air per liter of extracted water.

35 minutes ago, PB666 said:

I would draw your attention to the first post in the thread, because this rely's on a performances of RL10s at such a thrust that cosine losses are minimal.

How much are the customers willing to pay for an a high efficiency engine(s) that is only useful a few 1000 dV short of V_orbital that are hard to produce, expensive and currently in short supply. The replacement that would have been useful for such S2 staging to GTO for large payloads . . . .the F-2X was mothballed . . . .so . . . . . . . . .

Proof of the pudding is in the eating, while they list 19,200 PL to GTO, their prices (551) are $153,000,000 for 8900 to GTO.  SpaceX offers 14,200 to GTO (fully expendable) but 8,000 kT to GT0, they charge  $90,000,000 M
To arrive at 62KT in LEO you would need 4@ATLAs V 551 = $600 million. So they are only 60% more expensive to GTO and 700% more expensive to LEO . . . . . . . .

I agree. Doug isn't quite right; specific impulse on the terminal stage is important, but other issues (like dry mass and TWR) are also important. That's why even a solid-fueled kick stage can beat hydrolox if the kick stage has a low enough dry mass (not that that's the case here; just saying). A high-thrust kerolox lifter makes mincemeat out of gravity drag on the ascent, saving lots of fuel for the orbital stage.

And yes, the proof is in the eating. If SpaceX can deliver 12 tonnes to GTO for $95M, where is ULA's 8.9 tonnes for $150M or more?

The Falcon family upper stage carries five times as much propellant as the Centaur. For anything other than very, very small payloads, it will pack more dV than the Centaur every time.

A 450-second isp stage needs to burn 46% of its gross mass in order to get from LEO to GTO. A 345-second-isp stage needs to burn 55% of its gross mass in order to get from LEO to GTO. 

[sevenperforce]

Fun:

 

[tseitsei89]

1 hour ago, PB666 said:

I would draw your attention to the first post in the thread, because this rely's on a performances of RL10s at such a thrust that cosine losses are minimal.

How much are the customers willing to pay for an a high efficiency engine(s) that is only useful a few 1000 dV short of V_orbital that are hard to produce, expensive and currently in short supply. The replacement that would have been useful for such S2 staging to GTO for large payloads . . . .the F-2X was mothballed . . . .so . . . . . . . . .

Proof of the pudding is in the eating, while they list 19,200 PL to GTO, their prices (551) are $153,000,000 for 8900 to GTO.  SpaceX offers 14,200 to GTO (fully expendable) but 8,000 kT to GT0, they charge  $90,000,000 M
To arrive at 62KT in LEO you would need 4@ATLAs V 551 = $600 million. So they are only 60% more expensive to GTO and 700% more expensive to LEO . . . . . . . .

 

What I would like to see is a clear comparison between different versions of atlas, delta iv, F9 and FH.

How much they cost (recoverable and expendaple in falcon cases) and how much payload they can deliver to LEO and GTO.

Googling this gave me a whole bunch of widely varying results, especially for the cost part...

[magnemoe]

3 hours ago, sevenperforce said:

Oh, interesting.

Another tweet:

DATA GLORIOUS DATA

Does anyone have a guess as to what he means by performance? Does he mean that landing the side boosters and expending the core can lift a payload to a specified orbit 90% the size of what a fully-expended FH can do?

GPS for landing pad accuracy; radar for the actual landing. 

Data overload, so you could put +50 ton into LEO for $95M. How about landing the core on another drone ship? 

[CatastrophicFailure]

28 minutes ago, magnemoe said:

Data overload, so you could put +50 ton into LEO for $95M. How about landing the core on another drone ship? 

Only if you want to recover a charcoal briquette.  The core would be going so fast at that point recovery would be extremely difficult. 

 

1 hour ago, sevenperforce said:

agree. Doug isn't quite right; specific impulse on the terminal stage is important, but other issues (like dry mass and TWR) are also important. That's why even a solid-fueled kick stage can beat hydrolox if the kick stage has a low enough dry mass (not that that's the case here; just saying). A high-thrust kerolox lifter makes mincemeat out of gravity drag on the ascent, saving lots of fuel for the orbital stage.

And yes, the proof is in the eating. If SpaceX can deliver 12 tonnes to GTO for $95M, where is ULA's 8.9 tonnes for $150M or more?

The Falcon family upper stage carries five times as much propellant as the Centaur. For anything other than very, very small payloads, it will pack more dV than the Centaur every time.

A 450-second isp stage needs to burn 46% of its gross mass in order to get from LEO to GTO. A 345-second-isp stage needs to burn 55% of its gross mass in order to get from LEO to GTO

Ironic with this line of discussion, or maybe not, ULA’s just sent out a bunch of tweets extolling the virtues of their DIVH. One might think they sounded a bit... nervous.