totm nov 2023 SpaceX Discussion Thread

[tater]

Of course now it seems aimed at NOLA.  

[MatterBeam]

3 minutes ago, Spaceception said:

I think that would be a great idea, and it'd allow them to test new systems, including using a Raptor in vacuum which could give them a bunch of data for Mars missions as they build the full scaled version.

Definitely. Everyone else is building sub-scale versions of the new designs. I believe in SpaceX's ingenuity, but not in a near-magical ability to escape standard testing procedures.

[Spaceception]

20 minutes ago, MatterBeam said:

Definitely. Everyone else is building sub-scale versions of the new designs. I believe in SpaceX's ingenuity, but not in a near-magical ability to escape standard testing procedures.

It'd be cool PR too. And could give investors more faith in them so they get mo' 

You know, now that I think about it, since the BFR is supposed to be lighter than their regular rockets, and the Rapter is more powerful/efficient, could the payload mass of the Falcon 9 (maybe heavy) increase at all?

Edited October 5, 2017 by Spaceception

[wumpus]

12 minutes ago, MatterBeam said:

Definitely. Everyone else is building sub-scale versions of the new designs. I believe in SpaceX's ingenuity, but not in a near-magical ability to escape standard testing procedures.

How small is the sub-scale New Glenn?  I've been surprised at the sudden switch to massive rockets, but for all I know they could be starting with a scale edition.

[MatterBeam]

Just now, Spaceception said:

It'd be cool PR too. And could give investors more faith in them so they get mo' 

I wonder how it would look like, or what its performance would be. One thing for sure, it would have to be quite performant and might not be able to make a retro-propulsive maneuver once it achieves orbit.

The latest Falcon 9 stage has a mass ratio of 19.5 and an Isp of 311s. The second stage is assumed to use the 375s Raptor engine. We want a deltaV of 9500m/s total, so putting everything together, I get a second stage dry mass of 26.6 tons and wet mass of 111 tons. This means that the Falcon 9 booster can launch the usual payload (111 tons upper stage) and return, while the second stage pushes into orbit. Adding two tons more of propellant to the upper stage (dry mass 26.6 to 24.6 tons) gives it an extra deltaV of 300m/s, which should be juuuuust enough to deorbit and make a retro-propulsive landing.

That's 4296m/s of deltaV in the Falcon stage, and 5526m/s in the miniBFR stage. 

I don't know about you, but a 25ish ton spaceship in orbit which can be fuelled to 5.5km/s deltaV is very very cool. That's enough to go to Mars! 

[Spaceception]

1 minute ago, MatterBeam said:

I don't know about you, but a 25ish ton spaceship in orbit which can be fuelled to 5.5km/s deltaV is very very cool. That's enough to go to Mars! 

Free return mission? It'd be one hell of a stunt.

[MatterBeam]

6 minutes ago, Spaceception said:

Free return mission? It'd be one hell of a stunt.

Probably unmanned.
The ITS was designed for a mass ratio of 6700/275: 24.36. The BFR was designed for a mass ratio of 1185/85: 13.9. If the miniBFR only achieves a mass ratio of 10, it would have a dry mass of 11 tons. 

This gives it a payload capability of 15.6 tons, which can be satellites, maneuvering propellant or retropropulsion propellant. If it needs 400m/s to de-orbit and land, then it needs to save at least 1.75 tons of propellant using 275s Isp sea-level engines. Therefore, the maximum payload with return is 13.8 tons.

That is a useful payload to LEO!

On the other hand, if the entire payload capacity was replaced with propellant, plus a 1.75 ton reserve for landing, it would achieve a deltaV of ln(111/11.75)*375*9.81: 8261m/s. That's enough to go practically anywhere in the solar system... enough for a 6.57km/s flyby of Jupiter plus 1691m/s for maneuvers!

It would be unmanned of course, and the human habitation amenities replaced with radiation shielding, long-range communications and extra thermal protection for the faster re-entry.

[CatastrophicFailure]

15 minutes ago, MatterBeam said:

On the other hand, if the entire payload capacity was replaced with propellant, plus a 1.75 ton reserve for landing, it would achieve a deltaV of ln(111/11.75)*375*9.81: 8261m/s. That's enough to go practically anywhere in the solar system... enough for a 6.57km/s flyby of Jupiter plus 1691m/s for maneuvers!

“You have recovered a vessel from the orbit of Jupiter. +3000 science.”

But seriously, cool concept but that would mean extra tooling, extra development time, and still needing people on the F9 assembly line, likely delaying the real, already micronized ITS. 

 

 

Also, according to this article, delay is due to needing “minor engine rework.”

Edited October 5, 2017 by CatastrophicFailure

[sh1pman]

Given enough time and money, you can do great many things. But micro-BFR, just like Falcon-9 and Heavy, is going to become obsolete once the full scale BFR is done. It'll probably never recoup its development cost.

[tater]

'Full scale BFR" was a notional design, anyway. It was less, not more likely, to recoup dev costs. Mars is a money sink, that will never recoup any cost spent on it (replies should be sent to the thread for that subject: 

 

[sh1pman]

19 minutes ago, tater said:

(replies should be sent to the thread for that subject: 

Where have I ever mentioned colonization of anything? I was talking about BFR and how it will render every other rocket useless and their development pointless. 

 

[JedTech]

17 minutes ago, sh1pman said:

Where have I ever mentioned colonization of anything? I was talking about BFR and how it will render every other rocket useless and their development pointless. 

 

I own a fully reusable Nissan, and yet other manufacturers continue to develop other makes of cars.

[tater]

25 minutes ago, sh1pman said:

Where have I ever mentioned colonization of anything? I was talking about BFR and how it will render every other rocket useless and their development pointless. 

 

You didn't, I did, lol.

[sh1pman]

Just now, tater said:

You didn't, I did, lol.

Sorry, I was under the impression you were replying to my post. Never mind then.

10 minutes ago, JedTech said:

I own a fully reusable Nissan, and yet other manufacturers continue to develop other makes of cars.

TBH, I was talking about existing SpaceX rockets and the imaginary mini-BFR (since this is, you know, a SpaceX thread). So, about your fully reusable Nissan. Imagine if there were only expendable cars: you buy one, drive it once, and then throw it away. And then Nissan develops a fully reusable car, making every other car obsolete.

[Bill Phil]

9 minutes ago, sh1pman said:

Sorry, I was under the impression you were replying to my post. Never mind then.

TBH, I was talking about existing SpaceX rockets and the imaginary mini-BFR (since this is, you know, a SpaceX thread). So, about your fully reusable Nissan. Imagine if there were only expendable cars: you buy one, drive it once, and then throw it away. And then Nissan develops a fully reusable car, making every other car obsolete.

Then the other companies will respond in kind.

[sh1pman]

1 minute ago, Bill Phil said:

Then the other companies will respond in kind.

They surely will.

[MatterBeam]

2 hours ago, sh1pman said:

Given enough time and money, you can do great many things. But micro-BFR, just like Falcon-9 and Heavy, is going to become obsolete once the full scale BFR is done. It'll probably never recoup its development cost.

I personally don't think there's a market for the 150 ton payloads of the BFR, much less the hundreds of tons the ITS would have put into LEO. A lot of research has gone into making satellites smaller, to the point where there are no commercially available space-based systems that will fill even 10% of the BFR's cargo capacity. Sure, there are government plans to put tons of stuff into orbit for a Mars mission, but as their habit of cancelling everything proves, it is unwise to rely on government spending. 
So, we must focus on the commercial sector. The BFR would transport significant numbers of people  and amounts of payload across intercontinental to interplanetary distances. That's good. But until you have companies clamoring for dozens of tons in space per launch, the BFR will not be commercially viable.

SpaceX might add up the payloads of several companies to fill one BFR. It must do so at a quick rate, rapidly enough to fulfill its promise of low $/kg rates. The problem is, there are not enough companies putting that much mass up for delivery to space! It is like building a super tanker to transport diamonds. You might eventually fill it up, but it'll take a long time and the demand for it will be very low!

The main advantage of the miniBFR suggestion is that it can handle the vast majority of space contracts with about 15 tons of payload capacity, and it will remain profitable when you cannot fill the full 150 tons of the BFR. In today's world of microsatellites as low-mass, high-efficiency satellites, it is especially relevant.

57 minutes ago, Bill Phil said:

Then the other companies will respond in kind.

Imagine a SpaceX-2. A billion-dollar start up that tackles Elon Musk at large-scale low-cost space launches, instead of the plethora of small-scale attempts. I wonder what solutions it will come up with. 

[JedTech]

3 minutes ago, MatterBeam said:

I personally don't think there's a market for the 150 ton payloads of the BFR, much less the hundreds of tons the ITS would have put into LEO. A lot of research has gone into making satellites smaller, to the point where there are no commercially available space-based systems that will fill even 10% of the BFR's cargo capacity.

I'm sure they could do a lot more if the requirements of each project did not necessitate such light weight solutions. They could use sturdier materials, have larger instruments, stronger signals, extra fuel...
I think there will be lots of market for it, IF it becomes economically plausible.

[sh1pman]

1 minute ago, MatterBeam said:

I personally don't think there's a market for the 150 ton payloads of the BFR, much less the hundreds of tons the ITS would have put into LEO. A lot of research has gone into making satellites smaller, to the point where there are no commercially available space-based systems that will fill even 10% of the BFR's cargo capacity. Sure, there are government plans to put tons of stuff into orbit for a Mars mission, but as their habit of cancelling everything proves, it is unwise to rely on government spending. 
So, we must focus on the commercial sector. The BFR would transport significant numbers of people  and amounts of payload across intercontinental to interplanetary distances. That's good. But until you have companies clamoring for dozens of tons in space per launch, the BFR will not be commercially viable.

SpaceX might add up the payloads of several companies to fill one BFR. It must do so at a quick rate, rapidly enough to fulfill its promise of low $/kg rates. The problem is, there are not enough companies putting that much mass up for delivery to space! It is like building a super tanker to transport diamonds. You might eventually fill it up, but it'll take a long time and the demand for it will be very low!

The main advantage of the miniBFR suggestion is that it can handle the vast majority of space contracts with about 15 tons of payload capacity, and it will remain profitable when you cannot fill the full 150 tons of the BFR. In today's world of microsatellites as low-mass, high-efficiency satellites, it is especially relevant.

Imagine a SpaceX-2. A billion-dollar start up that tackles Elon Musk at large-scale low-cost space launches, instead of the plethora of small-scale attempts. I wonder what solutions it will come up with. 

I think that the demand for putting things in space is low partially because the cost of it is so high. Should it be made WAY cheaper with reusable rockets, the market for it will surely grow. Tourism, for example. If you can put 150t in orbit in one go, why not build a space hotel? Or casino? Or a luxury space liner doing free-return trips to the Moon? Billionaires can afford to go to space as tourists today, imagine if it was affordable to middle-class people.

[Bill Phil]

1 hour ago, sh1pman said:

I think that the demand for putting things in space is low partially because the cost of it is so high. Should it be made WAY cheaper with reusable rockets, the market for it will surely grow. Tourism, for example. If you can put 150t in orbit in one go, why not build a space hotel? Or casino? Or a luxury space liner doing free-return trips to the Moon? Billionaires can afford to go to space as tourists today, imagine if it was affordable to middle-class people.

There's a difference between demand and quantity demanded. Basically (really basic...) the demand increases when the price decreases. This may not directly apply to space travel though.

[MatterBeam]

32 minutes ago, JedTech said:

I'm sure they could do a lot more if the requirements of each project did not necessitate such light weight solutions. They could use sturdier materials, have larger instruments, stronger signals, extra fuel...
I think there will be lots of market for it, IF it becomes economically plausible.

There will be a significant delay between the capability appearing and the satellite companies retooling to make full use of the capability. Considering how tightly regulated the industry is, it won't switch over quickly...

[Mitchz95]

6 hours ago, Bill Phil said:

Then the other companies will respond in kind.

This is what Elon is banking on, even more than that Mars colony. He doesn't just want SpaceX and Tesla to dominate their respective industries, he wants the other companies to play catch-up and develop their own competitive vehicles, so we can move forward as a species.

In a way, he's already succeeded. Even if SpaceX went under tomorrow, they've proven re-usable rockets are possible, and China and Blue Origin are already building their own. Ditto with Tesla; GM and Volvo are already going full-EV.

Edited October 6, 2017 by Mitchz95

[kerbiloid]

2 hours ago, Mitchz95 said:

he wants the other companies to play catch-up and develop their own competitive vehicles, so we can move forward as a species.

Looking at his and Bezos' conversation after Blue Origin's first reused rocket, unlikely he wants this...

Edited October 6, 2017 by kerbiloid

[magnemoe]

7 hours ago, MatterBeam said:

There will be a significant delay between the capability appearing and the satellite companies retooling to make full use of the capability. Considering how tightly regulated the industry is, it won't switch over quickly...

This. It will take time for satellite operators to change designs. More shielding and redundancy would be two obvious things to add if weight did not matter so much. 
One interesting thing you could bundle with the BFR would be an reusable tug for GTO missions, You put satellite on tug, launch to LEO, tug takes satellite to GTO and return to BFR. 
 

[rudi1291]

Would a F9 upper stage fit into BFR?