Rocketry General Thread

[JB47394]

At 20 bucks a pound, payback will be very healthy.

Not if nobody has anything to launch on the thing. Sure, if BFR is another increment in cost reductions for putting satellites in orbit then it’ll be profitable and goodness will ensue. But at some point, we’ll have enough satellites up and that business will level off or even decrease.

What’s needed is new businesses in space. Stuff besides satellites. There are government prestige projects, and if the world economy keeps moving along then those might be enough to make Musk a trillionaire. I don’t know. I think it would be far healthier for BFR and follow-ons if they were supporting a substantial economic machine.

That’s why I mentioned solar stations, space hotels, mining, and so on. It may be that everyone and his cousin is champing at the bit to get started and there’s just no viable way of doing it because rocketry is so expensive. Perhaps BFR will be like the web, and begin an explosion in growth.

As I said, it’s an unknown, and it’s the fundamental challenge that the whole endeavor faces; will anyone want to use those capabilities?

[Alkan2]

will anyone want to use those capabilities?

That’s like asking if anyone will want to use the transcontinental railroad. I’ll just start off with a few things:

This is what would start hapening, roughly speaking right away if BFR was flying:

• Bigelow aerospace will want to test larger modules at zero g.
• Many, many more experiments - more rigorous ones - could happen in zero g.
• NASA would dump SLS and use BFR for their other missions. Especially if SpaceX landed people on Mars. That would basically be grabbing NASA by the balls.
• Asteroid mining would be profitable if launch costs were the only factor. Extraction rates of precious metals will determine the profitability, but profits would likely be high. Substantial research into this will be enabled by BFR. There are already people who would pay for launches with venture capital to do this research.
• Filming a movie using actual micro-gravity would actually be affordable for blockbuster movies. A green screen setup in a BFR cabin. Out of a budget of hundreds of millions for many of these movies, spending 10 million on filming in space is feasible. Anyone want to bet that James Cameron will do this?
• Space tourism would be profitable. There are plenty of people who would go to space for less than a hundred thousand dollars. Further improvements in safety will be needed for this.
• Some manufacturing processes would be made easier or even just possible at all in microgravity.
• Mining fuel to support these activities would also be beneficial. That’s why SpaceX is already working on the fuel production machinery for Mars.
• Significant increases in communication will be needed to support all of this stuff. Satellite launches will become more frequent and more satellites will be launched. Phone and internet everywhere on the planet.
• Not for profit, but in development is SpaceX’s Mars colony, creating infrastructure for fuel in space - also economically driven by people who will simply want to go. MASSIVE marketing advantage to being the first ones to Mars. What better advertisement could you have than the greatest achievement in human history? He’s right to go to Mars. It’s going to blindside everyone - rocking the world.

Summary: Elon Musk already foresees this being an explosion, so he’s going to start working on BFR v2 pretty quickly after V1 is flying, concurrently with everything else.

[JB47394]

That’s like asking if anyone will want to use the transcontinental railroad.

No, the railroad is analogous to the Falcon 9. Travel between the coasts was already in place, and the railroad only did it better. Satellites were already being launched, and Falcon 9 did it better. So SpaceX ate everyone else’s lunch and was profitable. Right now, there is no market beyond that - other than government prestige projects.

[Alkan2]

No, the railroad is analogous to the Falcon 9. Travel between the coasts was already in place, and the railroad only did it better. Satellites were already being launched, and Falcon 9 did it better. So SpaceX ate everyone else’s lunch and was profitable. Right now, there is no market beyond that - other than government prestige projects.

Are you serious? The Falcon 9 costs ~1000 a pound. Whatever the Falcon 9 can do, the BFR will do at a lower cost for ANY payload. At 20 dollars a pound, space will be extremely accessible. It will be very accessible at 200 dollars a pound - and that market will make SpaceX billions. The falcon 9 is like if the continental railroad stopped before the rockies. It’s still expensive and dangerous.

Right now, there is no market beyond that - other than government prestige projects.

This is just patently false. There is a market to take humans to low earth orbit for fun. It’s just that no one can cater to that market yet. Out of 7 billion people, do you really think that zero of them have the money and are willing to take the risk to experience going to space on a human-rated BFR rocket? At a ticket price of 15,000 dollars, 70% of the U.S. could save up to be able to afford to go: ~224 million people.

In the world it’s probably about another billion or two who could afford to go. If .1% of those people would be willing to pay for a ride, you still have a market of 220,000. Catering to those people would net you about 700 launches, and at a profit of ~5 million a launch, we’re talking a profit of 3.5 billion dollars. The market is probably higher and they can probably charge a lot more. This is the easiest market to cater to because you don’t have to actually leave anything in orbit or achieve a specific orbit. Just fly up and down, maybe for a few hours to a couple of days.

SpaceX will face the nearly impossible challenge of actually meeting demand. So, they’ll be able to charge a LOT for a long time and make billions of dollars, making them one of the most profitable companies in the world.

They’ll start out at like 20-30 launches a year on BFR at a profit of ~50-100 million, so ~1.8 billion dollars. The next year will be like 30-40 launches. That should go up to more like 60, 100, 150. The price they charge will drop as this number goes up.

[Skyentist]

They’ll start out at like 20-30 launches a year on BFR

No they will start with one or two. Then check out the data, make adjustments…maybe rebuild/redesign certain parts. Possibly replace the heatshield tiles for safety and to see how they faired. If BFR follows the path falcon9 took they will hit (18)20 launches 7 years after they begin flying. Maybe faster with the reuse procedures learned from falcon9 but not by much. There are still the vehicle specific growing pains that will occur from the design choices made. Who knows what they will be…if we knew them now they could design around them and that’s the whole point.

I don’t think the full stack will fly before 2020, and 2022 is more likely(still optimistic to go from manufacture of largest launch vehicle ever to launch in 4 years) but that still makes the 20-30 launches per year estimate in the late 2020s. That is still extremely optimistic…

As far as the end result of what BFR means for spaceflight goes I can agree with you. I just think that your timelines need to be shifted to the right by a decade or so. I would love to be proven wrong and would love to help prove myself wrong, but engineering is what it is. There are some problems that will only be found/solved with time and use of the vehicle and you can’t get around that.

[Alkan2]

No they will start with one or two.

After they get past the adjustment/data phase. It’ll hit 20 launches a year faster than the Falcon 9.

Possibly replace the heatshield tiles for safety and to see how they faired.

They don’t use tiles. It’s one big piece. The shuttle used thermal soak tiles. The BFR uses an ablative heat shield. So, it degrades after each use. So, it’s analogous to a clutch or brake pad, which will need eventual replacing. But it’ll be one big chunk, not by the tile. Tiles are a major design flaw.

If BFR follows the path falcon9 took they will hit (18)20 launches 7 years after they begin flying.

With the Falcon 9, the largest thing they had ever launched was the Falcon 1, barely. Now they have the team that developed reusable rockets developing the BFR full time once Block 5 is flying.

There are still the vehicle specific growing pains that will occur from the design choices made.

Of course. That’ll most likely push the timeline back. I think that other factors will offset it.

I don’t think the full stack will fly before 2020, and 2022 is more likely(still optimistic to go from manufacture of largest launch vehicle ever to launch in 4 years) but that still makes the 20-30 launches per year estimate in the late 2020s. That is still extremely optimistic…

So, they’re dropping further development on F9 and FH and it’s all going to BFR.

No one really knows how long it will be, including SpaceX, but I think the expected time is longer than they say, but shorter than the Falcon 9. They’re aiming for ~3 to launch. They’re probably going to do the Mars cargo missions as one of the first launches.

[Skyentist]

They don’t use tiles. It’s one big piece. The shuttle used thermal soak tiles. The BFR uses an ablative heat shield. So, it degrades after each use. So, it’s analogous to a clutch or brake pad, which will need eventual replacing. But it’ll be one big chunk, not by the tile. Tiles are a major design flaw.

Source on that? As far as I know they’ve given zero information on the direction they’ll take with the shielding. I just assumed tiles because of the shuttle and that’s how they are manufactured on dragon.

Wouldn’t you replace the tiles after the first landing? Not only to individually analyze the tiles to see where the most ablation happened and for the “just in case” factor to avoid losing the vehicle on the following reentry.

With the Falcon 9, the largest thing they had ever launched was the Falcon 1, barely. Now they have the team that developed reusable rockets developing the BFR full time once Block 5 is flying.

With the BFR, the largest thing they have ever launched and landed was the falcon 9.
They’re different vehicles entirely. Yes they know how to build the falcon 9. Just because you’re designing a new rocket using tech from your previous vehicles does not mean you know how to build it yet.

They’re aiming for ~3 to launch. They’re probably going to do the Mars cargo missions as one of the first launches.

Which is between the optimistic timeline I gave. I would assume they will get into orbit as their first couple of launches to prove that it can launch and land under the easiest of conditions and then practice refueling. Then do a moon free return to practice reentry from higher velocities without sending the vehicle outside the Earth’s sphere of influence. Going straight to Mars is a hail mary that is unnecessarily risking the vehicle.

Note: They need multiple vehicles to attempt an interplanetary mission because you need the actual BFS and at least 1 tanker to refuel it. First you need to figure out refueling which, for the record, has never been done to my knowledge. It will be a tricky problem to solve. There is a lot that happens between the first flight ever and the first rendezvous and then the first docking, and then the first refueling attempt.

I think you are oversimplifying the obstacles that SpaceX has to overcome. With every “They just have to do this” there are a million complicated items that have to be solved before it can happen. “They just need a docking adapter” “They just need a docking adapter with propellant ports.” “They just need a docking adapter with propellant flow ports that are sealed to vacuum as to not leak in space” “They just need to make this docking adapter with propellant flow ports that are vacuum sealed strong enough to withstand the centripedal forces of rotating during a propellant transfer manuever.” “They just need to make sure that bla bla bla forces in the lines don’t break the pumps etc etc.” There are a million complicated problems to overcome to just refuel.

A loss of vehicle will be a huge set back to human rated missions and something they need to be very careful about. Dragon is a tried and true type of vehicle that has 60 years of flight heritage that we have confidence in. BFR is moving to a similar design that resulted in the loss of 2 vehicles over 25 years of use. They need to be careful.

I have every confidence that they’ll figure it out but I’m trying to help you see that Mars at 2023 is a bit overzealous and that you should temper your expectations. It’s not going anywhere and we need to take it slow and steady.

[JB47394]

I just assumed tiles because of the shuttle and that’s how they are manufactured on dragon.

Which is not to say that Dragon uses Shuttle-style ceramic tiles. PICA is prepared in sections. That could be true for any number of reasons.

The Apollo capsules had one-piece AVCOAT shields. I found the process of installation fascinating. Unfortunately, I could only find the video that shows it on Vimeo.

[Red_Syns]

Just wanted to point out that my understanding is the BFR is supposed to be able to get to Mars, refuel using the Martian atmosphere, and return on that.

Since the first flight wouldn’t be manned anyway, its payload could be the conversion equipment, assuming that is a viable technology by then.

Edit: also assuming the equipment fits in a single trip.

[Skyentist]

Which is not to say that Dragon uses Shuttle-style ceramic tiles. PICA is prepared in sections. That could be true for any number of reasons.

Right. The point I was making was that the tiles are tiles/sections/whatever you want to call them and have to be installed individually. It’s going to be a time consuming process.

Didn’t know that about Apollo. Very cool video thanks!

Just wanted to point out that my understanding is the BFR is supposed to be able to get to Mars, refuel using the Martian atmosphere, and return on that.

To get to mars with a 100ton payload it needs 5-10 refueling flights in LEO before it has the necessary propellant for TMI and Mars landing. Once it’s there it refuels using propellant processed insitu.

The BFR isn’t going anywhere beyond LEO/GEO before multiple first stages and at least one payload version and one tanker version exists.

[JonnyRedHed]

[Alkan2]

I was mistaken about the use of tiles!

I was under the impression that visually it was one piece.

I have every confidence that they’ll figure it out but I’m trying to help you see that Mars at 2023 is a bit overzealous and that you should temper your expectations. It’s not going anywhere and we need to take it slow and steady.

Well, I don’t think it’s that important of an argument anyways. I know that there are a lot of details. Many they’ve solved, so it’s just a matter of trying it out. They’ve done a lot of the work already designwise, and it’s already been refined from the original ITS vehicle. So, that’s a lot of design that’s already been done. Building and manufacturing will likely present many challenges.

There’s one thing that gives me more confidence:

Elon Musk said that after the Falcon Heavy flew that he’s confident in BFR - because the same simulation software they used to simulate Falcon Heavy and make it work without a hitch is being used for BFR. So, on paper it’s looking good for BFR and a lot of these problems have conceptually been solved.

I think my estimation is 2022 or 2024 for cargo, but that they’re more likely to hit 2026 for humans on Mars than they are to hit 2022 cargo since 2024 cargo would mean many proven flights since you’d fly the refueler 5 times per launch. So, BFR may be a well proven spacecraft by 2026 even if they only hit 2024.

Landing a bunch of pressurized cargo on Mars would be a major feat. Once you do that it’s time for a scrapping of SLS. The real bummer will be if it blows up landing on Mars.

[JonnyRedHed]

[Alkan2]

Two uses in 24 hours! This year’s goal!

If they do this it will really bode well for BFR. If he launches a rocket without refurbishment, he proves a point that people never thought would be proven. Suddenly in orbit refueling seems less like a pipe d ream. And, of course stage two would return back to the launch pad since it would have circled the globe and dumped its energy coming in from the other direction.

So, if BFS works the same way - instant reuse, we really may be getting 20 dollars a pound sooner than later.

[Alkan2]

Main body tool for the BFR:

That thing just fills me with awe, knowing the final shape. That’s the thing they’re going to wrap the carbon fiber frame around (BFR will have a carbon fiber frame, apparently). Just look at the size of it.

Its worth noting that the probable charge of reusable rockets of SpaceX results in a higher profit. That is, with block 5 hitting no refurbishment between some flights, that does mean, absolutely a dramatic drop in cost that isnt reflected by stated reuse prices. So Falcon Heavy might enable a cost of more like 300 bucks a pound as is.

[Skyentist]

You actually beat me to the punch for posting the tooling. Very exciting to see ! I think its possible to see a completely assembled BFS airframe by mid next year like something similar to the dragon V2 reveal back in 2014ish. Mostly a mockup but the general design is will be there.

Suddenly in orbit refueling seems less like a pipe dream.

The issue isn’t having the engines fire without refurb…the issue is the transfer of cryogenic liquid in a micro-g environment. Something that can only be tested in orbit or on a vomit comet. The balancing of all those forces(not to mention plumbing) while having 2 large spacecraft attached is a nightmare.

[Alkan2]

The issue isn’t having the engines fire without refurb…the issue is the transfer of cryogenic liquid in a micro-g environment. Something that can only be tested in orbit or on a vomit comet. The balancing of all those forces(not to mention plumbing) while having 2 large spacecraft attached is a nightmare.

Zero g fluid mechanics is a problem that has to be dealt with for engine restarts in space. That’s already been done. Not sure how, need to look it up, but that already has happened.

[Red_Syns]

It’s not quite the same scale of problem. The end product of fuel in an engine is vapor: ideally, a craft to craft transfer would never leave liquid phase.

There is also the issue of getting the helium, which acts as a displacement agent, back into the storage tanks without contaminating the inside of those tanks.

A related problem is the pressures you’d ideally work with: on earth, you can use vertical storage to increase holding tank pressures. No such mechanism exists in zero g.

[Skyentist]

Zero g fluid mechanics is a problem that has to be dealt with for engine restarts in space. That’s already been done. Not sure how, need to look it up, but that already has happened.

You’re talking about ullage. This is where the RCS thrusters or small solid rockets are ignited to create acceleration which pushes all of the propellant to the bottom of the tanks. I know you’re not suggesting that that we fire RCS thrusters for the duration of the fuel transfer of many thousands of kilograms of propellant which could take hours because that’s not plausible.

What is plausible is a different method by rotate the two craft to create centripetal acceleration which can feed the propellant in the pumps. The propellant will still act strangely and the plumbing and pumps are far different than the plumping and turbopumps required to feed propellant to the engines.

There are still a lot of unknowns. Please don’t simplify the system to “we’ve done plumbing for engines so we can do it for a tanker” because it’s a completely different problem transferring 300kg/s to your combustion chamber ran by a turbopump and transfering at ?kg/s using a standard pump on some propellant with some weird viscosity due to it’s liquid state and some artificial gravity between 0 and 1. It’s never been done. Not to mention the docking system and ports that can automatically connect and seal for plumbing with zero human contact.

There is also the issue of getting the helium, which acts as a displacement agent, back into the storage tanks without contaminating the inside of those tanks.

Raptor engines use methalox which is autogenously pressurized in the fuel tanks. This means that the boiled off oxygen and methane are stored and used to repressurize the tanks as propellant is drained which eliminates the need for the COPV that have plagued falcon 9 development and are the cause of both vehicle failures. In short, no more helium or COPVs in BFR which is great news.

[Red_Syns]

Didn’t know that, sounds like a brilliant system.