totm nov 2023 SpaceX Discussion Thread

[cubinator]

Quote

“7 billion potential payloads”

That's the spirit!

[sh1pman]

7 billion potential payloads? What are they up to?

[tater]

13 minutes ago, sh1pman said:

7 billion potential payloads? What are they up to?

Humans.

She's saying that flying people will eventually be the majority of their business.

I honestly agree that human spaceflight is the "killer app" for the space business. All other payloads are finite. Flying people is only a matter of cost, and safety. Both are engineering problems to be solved, certainly, but they are not impossible problems.

[KSK]

6 hours ago, Xd the great said:

Just wondering, are the spacex draco engines strong enough to act as a OMS engine?

I thought they already were using Draco engines (as opposed to SuperDraco) as OMS engines for Dragon 1?

1 hour ago, cubinator said:

That's the spirit!

And the opportunity...

[sh1pman]

11 minutes ago, tater said:

She's saying that flying people will eventually be the majority of their business.

I got it that its humans. But flying them where? Mars? Some kind of Bigelow-style space hotel? That's hardly a market for 7 billion people, more like a couple hundred richest people at most.

Edited September 12, 2018 by sh1pman

[Xd the great]

5 minutes ago, sh1pman said:

I got it that its humans. But flying them where? Mars? Some kind of Bigelow-style space hotel? That's hardly a market for 7 billion people, more like a couple hundred richest people at most.

To Mars, Elon hopes it will be half a million.

Launch cost of bfr is 7 million ish for orbital stuff, 14x tonnes of payload.

And for suborbital hops, he states that it will be as expensive as an economy class air ticket.

[sh1pman]

7 minutes ago, Xd the great said:

And for suborbital hops, he states that it will be as expensive as an economy class air ticket.

Don't believe it at all. The math doesn't work out.

[tater]

15 minutes ago, sh1pman said:

I got it that its humans. But flying them where? Mars? Some kind of Bigelow-style space hotel? That's hardly a market for 7 billion people, more like a couple hundred richest people at most.

IMO, tourism.

Not Mars, but maybe, someday, the Moon. I'm thinking orbital, or even suborbital (point to point).

There is a thread about P2P, and I don't see the numbers working out with the current design assumptions, but if it could be demonstrably safe, then I think nearly anything is possible.

Forget current BFS plans for a moment (easy to get derailed by doing the math, lol), and assume that they solve the engineering issues around making such travel as safe and reliable as commercial airline traffic (or commercial airline traffic from several decades ago, anyway). If that could be done, I think the market for human spaceflight is effectively bottomless compared to the current commercial launch market. Solving those issues comes with orbital capability free, so then the notion of hotels, or some sort of brief, extended stay pretty straightforward.

Shotwell seems convinced that P2P at ~$2000/seat is a realistic business model (she claims it's a thing in 10 years, and she's not kooky-optimistic like her boss), and while I don't see the math working every time I try, she must know something we don't. Safety is the huge unknown, it's a non-starter without being insanely safe compared to every other rocket every flown (by orders of magnitude).

[Xd the great]

9 minutes ago, sh1pman said:

Don't believe it at all. The math doesn't work out.

As long as the cost for an suborbital hop is lower than half million

[tater]

9 minutes ago, sh1pman said:

Don't believe it at all. The math doesn't work out.

Yeah, it doesn't seem to every time I mess with the numbers (unless I used the full crew volume packed in as economy, and put 800 people in there).

 

[Xd the great]

6 minutes ago, tater said:

Yeah, it doesn't seem to every time I mess with the numbers (unless I used the full crew volume packed in as economy, and put 800 people in there).

 

That is probably elons plan. No legroom for half an hour is not a big problem. 

Not seeing space is.

[tater]

3 minutes ago, Xd the great said:

That is probably elons plan. No legroom for half an hour is not a big problem. 

This is true, but Shotwell specifically said closer to 100 passengers.

So the math doesn't work.

3 minutes ago, Xd the great said:

Not seeing space is.

This is true from a tourism standpoint. Hence my statement that they should charge more for window seats.

[insert_name]

Space IL is going up on a ride share arranged by spaceflight, with several other secondary payloads, some of which will be dropped off directly to gso

https://www.teslarati.com/spacex-falcon-9-rideshare-commercial-lunar-lander-2019/

[sh1pman]

42 minutes ago, Xd the great said:

As long as the cost for an suborbital hop is lower than half million

Suborbital launch should cost about the same as orbital for BFR. And if orbital is 7 million, then I don't see how you can bring it down to half a million for a suborbital one.

43 minutes ago, tater said:

Safety is the huge unknown, it's a non-starter without being insanely safe compared to every other rocket every flown (by orders of magnitude).

Safety and economics are huge unknowns indeed.

Edited September 12, 2018 by sh1pman

[tater]

1 minute ago, sh1pman said:

Suborbital launch should cost about the same as orbital for BFR. And if orbital is 7 million, then I don't see how you can bring it down to half a million for a suborbital one.

Props are a few hundred grand. The issue is maintaining the vehicles, and the number of flights before retirement.

If a vehicle is on the order of 230 million, then 1000 flights means that the thing only costs ~1 M$ to fly, not 7 (a few hundred grand for props, plus a quarter of a million in vehicle cost, and a couple hundred grand in operational cost). For 100 seats (Shotwell), that's 10k a seat to break even, well above the claimed price. If a % cost that much (windows), and the rest are cheaper, then they might be able to do it with only 100-something seats if the number if flights could be more like 2000.

Who knows. I'll believe it when I see it, but regardless, if it were possible, it's a huge market compared to flying sats to orbit.

[sh1pman]

12 minutes ago, tater said:

Who knows. I'll believe it when I see it, but regardless, if it were possible, it's a huge market compared to flying sats to orbit.

It really looks like a "sounds good, doesn't work" case. Like Concorde.

It has to be ridiculously safe (for a rocket) to be viable. No more than 1 in 1000 flights should end in a RUD and LOCV for the economics to work. Preferably much less than that.

It also has to fly ridiculously often (for a rocket) to pay for itself in a reasonable time. 

[tater]

Way, way safer than 1:1000 or it's a non-starter, IMO.

There are something like 100,000 flights a day right now. 100 fatal crashes a year would halt airline traffic until they figured it out, much less per day.

It's been a while since an airline crash, so we're literally talking them needing to have LOP (passengers, instead of crew) incidents on the order of 1:10,000,000 I would think.

So while I'm happy to mess with where they'd have to be to make it work economically from a direct cost standpoint, the safety thing makes it all moot, anyway.

[NSEP]

By the time SpaceX has the tech to launch that many people into space, the world population would have probably already surpassed 9 billion. Heck, right now, the world population already rounds up to 8 billion, and the fact that people are still behind on that just shows that the population is skyrocketing. get it?

[AVaughan]

9 hours ago, tater said:

If a vehicle is on the order of 230 million, then 1000 flights means that the thing only costs ~1 M$ to fly, not 7 (a few hundred grand for props, plus a quarter of a million in vehicle cost, and a couple hundred grand in operational cost). For 100 seats (Shotwell), that's 10k a seat to break even, well above the claimed price. If a % cost that much (windows), and the rest are cheaper, then they might be able to do it with only 100-something seats if the number if flights could be more like 2000.

If you change those numbers to 10,000 flights, (eg 3 flights per day, for nearly 10 years, which is probably closer to an airliner's lifespan than the 1000 flights you were proposing), with an average of 100 passengers per flight, then you get to $2230 per flight to break even.  That is assuming $200,000 of propellant per flight, but has no allowance for any flight crew wages, maintenance costs or terminal cost/fees.  I expect Musk is planning for BFR to be fully automated, and for an hour long flight, you don't really need cabin service.  But you potentially do need cabin crew make sure passengers are seated and strapped in for re-entry, and you will almost certainly need some sort of maintenance and inspection program, and will definitely have costs associated with providing a passenger terminal/boarding passengers etc.  If you can bump the number of passengers up to 250 and/or reduce fuel costs, (eg maybe make methane + Lox from water and atmospheric CO₂ powered from solar panels, and amortise that over 10+ years), assume no flightcrew, and just a ticket inspect level of expense at the terminal, then maybe the numbers work. 

But all of that ignores the safety aspect.  Personally I'm not sure that SpaceX will ever be able to get BFR man-rated by NASA for Earth launch/landing without some sort of concessions to crew escape in the event something going wrong during launch/landing.  I expect that FAA approval of BFR for passengers flights would also be difficult.  (Note I'm absolutely not an expert on what NASA or the FAA requires for Human-rated spacecraft, the above is just my personal and sceptical opinion).

 

[cubinator]

9 hours ago, NSEP said:

By the time SpaceX has the tech to launch that many people into space, the world population would have probably already surpassed 9 billion. Heck, right now, the world population already rounds up to 8 billion, and the fact that people are still behind on that just shows that the population is skyrocketing. get it?

Haha, ha, ha...that's actually rather unsettling.  

[Bill Phil]

10 hours ago, NSEP said:

By the time SpaceX has the tech to launch that many people into space, the world population would have probably already surpassed 9 billion. Heck, right now, the world population already rounds up to 8 billion, and the fact that people are still behind on that just shows that the population is skyrocketing. get it?

Yeah. But rounding up is adding hundreds of millions to the population, the equivalent of many countries.

[NSEP]

7 hours ago, Bill Phil said:

Yeah. But rounding up is adding hundreds of millions to the population, the equivalent of many countries.

Yeah but if we keep using 7 billion its we are missing the 700 million kids.

Its just better to say 7.7 to be honest. Anyways, this is getting off topic so im leaving it here.

[sevenperforce]

On 9/10/2018 at 3:25 PM, Ultimate Steve said:

It probably has a little bit of room left. If the gimbal only affects the nozzle, and the pusher reaches up to almost the combustion chamber, then the part of the nozzle that actually moves will be able to so so without obstruction to a certain extent.

I believe the Merlin 1D gimbals only the nozzle, not the chamber. The pusher is in contact with the throat of the chamber.

On 9/10/2018 at 6:36 PM, Xd the great said:

Tbh, i dont think gimballing is needed on stage 2. They have rcs for deorbitong the stage, anyway.

Yes, stage 2 absolutely needs gimbal. Gimbal is far more dV-efficient than RCS for attitude control. RCS is only for roll control, and when the deorbit the stage, they do so by venting through the nozzle, not with RCS.

On 9/12/2018 at 4:10 AM, Xd the great said:

Just wondering, are the spacex draco engines strong enough to act as a OMS engine?

Draco engines are already used as OMS engines, if you mean orbital maneuvering in general.

If you mean "can Draco engines be used to circularize a barely-suborbital orbit" then the answer is no, not really. They have enough thrust, clustered (after all, the Shuttle's OMS only produced about 0.04 gees of acceleration during circularization), but thrust pod tanks are not large enough to give it significant dV.

[sevenperforce]

23 hours ago, tater said:

Props are a few hundred grand. The issue is maintaining the vehicles, and the number of flights before retirement.

If a vehicle is on the order of 230 million, then 1000 flights means that the thing only costs ~1 M$ to fly, not 7 (a few hundred grand for props, plus a quarter of a million in vehicle cost, and a couple hundred grand in operational cost). For 100 seats (Shotwell), that's 10k a seat to break even, well above the claimed price. If a % cost that much (windows), and the rest are cheaper, then they might be able to do it with only 100-something seats if the number if flights could be more like 2000.

Who knows. I'll believe it when I see it, but regardless, if it were possible, it's a huge market compared to flying sats to orbit.

I wonder if they can do a partial prop load on S1 for the P2P hops. BFS can almost make an antipodal P2P flight with no first stage at all, so it could get away with a much lower separation speed. Saves wear on the booster, reduces propellant costs. The bulk of the propellant cost is on the first stage.

[Jaff]

13 hours ago, AVaughan said:

If you change those numbers to 10,000 flights, (eg 3 flights per day, for nearly 10 years, which is probably closer to an airliner's lifespan than the 1000 flights you were proposing), with an average of 100 passengers per flight, then you get to $2230 per flight to break even.  That is assuming $200,000 of propellant per flight, but has no allowance for any flight crew wages, maintenance costs or terminal cost/fees.  I expect Musk is planning for BFR to be fully automated, and for an hour long flight, you don't really need cabin service.  But you potentially do need cabin crew make sure passengers are seated and strapped in for re-entry, and you will almost certainly need some sort of maintenance and inspection program, and will definitely have costs associated with providing a passenger terminal/boarding passengers etc.  If you can bump the number of passengers up to 250 and/or reduce fuel costs, (eg maybe make methane + Lox from water and atmospheric CO₂ powered from solar panels, and amortise that over 10+ years), assume no flightcrew, and just a ticket inspect level of expense at the terminal, then maybe the numbers work. 

But all of that ignores the safety aspect.  Personally I'm not sure that SpaceX will ever be able to get BFR man-rated by NASA for Earth launch/landing without some sort of concessions to crew escape in the event something going wrong during launch/landing.  I expect that FAA approval of BFR for passengers flights would also be difficult.  (Note I'm absolutely not an expert on what NASA or the FAA requires for Human-rated spacecraft, the above is just my personal and sceptical opinion).

 

2 things.

 

you forgot about the boat that needs to take the passengers to the offshore platform and the platform maintenance etc. 

 

And why do those American federal associations have to do with anything to do with bfr suborbital? They could do London to Sydney to prove it works and can be safe until they even bother with anything to do with America