Pivot to BFR

[nacnud]

Suppose for a moment that you are Gywnne Shotwell.  It's late 2018...

There is pretty much no difference in moving a 9 vs 12 meter rocket...

Except you have a facility that can produce 9m rockets. You don't have on that can produce 12m ones.

[DreamyPickle]

There is pretty much no difference in moving a 9 vs 12 meter rocket, neither one is going down a California freeway.

Except there is an Elon tweet where he explicitly said 9 meters fits into existing facilities. This almost certainly means that they also decided on a transportation path to a barge. They might even have preliminary agreements with city hall and such.

The F9 diameter was chosen a long time ago based on the maximum that could be trucked across the country. This new 9 meter diameter is also based on logistical concerns and will not change for a very long time. The 12 meter ITS is dead.

[hkultala]

Suppose for a moment that you are Gywnne Shotwell.  It's late 2018, you've recovered a few F9 Block 5 boosters, and the Raptor team hasn't had a RUD on the test stand in six months.  Fairing capture and reuse are just starting.
 You are certain that the BFR that you build will be reused at least ten times. 

How big a BFR do you want to build?

Does it really matter if it has 31 or 42 Raptors? You already have the 12 meter tooling -- you built that when you built the test tank.  Fuel is still a small part of your launch costs, and you don't have to fill the BFR tanks completely when you launch.  There is pretty much no difference in moving a 9 vs 12 meter rocket, neither one is going down a California freeway.

Very badly wrong:

1) They have a 170 tonne engine. Not 300 tonne engine. 42 of those 170 tonne engines don't have enough thrust for 12-meter core.

2) They do not have 12-meter tooling in hawthorne. They say that 9 meters is biggest that their factory can build.

somewhere they've had mold for ONE of the six tanks required. That's very different than having "tooling for 12 meters".

I think they should build the full-size BFR.  They can leave off some engines and partially fill the tanks if they want to save a few bucks.  The launch cradle, recovery cradle, vertical integration cranes, setbacks for noise and safety, these can all be sized for the full BFR.

BFR/BFS works because of very good mass fraction. Oversized tanks would ruin this mass fraction as they would weight twice as much.

So you propose building a rocket that they cannot build, and even if they could build, would have worse performance and higher cost than what they are building.

[JasonAW3]

At that pivot, all other subs in the world became obsolete.

which is not true

Pretty close to it Jim.

     There are some Fuel Cell based subs coming on line, and some countries still use diesel boats, but, even with the best sound suppression available, the diesel boats are still pretty noisy.

      Overall, nuke boats have pretty much made all non-nuke subs obsolete.

[FutureSpaceTourist]

Some interesting statements by SpaceX Senior Director Tom Ochinero:

SpaceX reassures commercial satellite market: Falcon 9 won’t soon be scrapped for BFR

by Peter B. de Selding | Oct 12, 2017

https://www.spaceintelreport.com/spacex-reassures-commercial-satellite-market-falcon-9-wont-soon-scrapped-bfr/

[sanman]

I understand that they don't want to spook existing/prospective customers into fretting that F9R won't be available - but then how do they intend to reap the benefits of repurposing all those staff onto BFR?

The answer to this might be seen in the "production hell" and missed targets happening at Tesla right now. SpaceX may simply fall short of their ambitious target by a wide margin. Oh well, at least there's no stock price for them to worry about.

[envy887]

I understand that they don't want to spook existing/prospective customers into fretting that F9R won't be available - but then how do they intend to reap the benefits of repurposing all those staff onto BFR?

The answer to this might be seen in the "production hell" and missed targets happening at Tesla right now. SpaceX may simply fall short of their ambitious target by a wide margin. Oh well, at least there's no stock price for them to worry about.

The answer is F9 reuse. Once a significant majority of Falcon launches are on used boosters, they can slow production to a crawl an move most of those resources to the BFR factory.. Right now they can't make and test Falcon boosters fast enough.

[rockets4life97]

I'm really interested to watch this transition occur over the next several years. I expect the transition will be incremental and based on hitting early development milestones. If those milestones take longer (e.g. raptor development), then the whole transition will be stretched out.

I'm optimistic about BFR and at the same time expect we'll still be seeing F9 and FH flights in 2025 even if BFR flies before then.

[robert_d]

     What about building a version of the booster first, but use it to launch the existing Falcon 2nd stage and fairing? Use it to replace any Falcon Heavy missions. Could stretch the 2nd stage if it made sense. Something like 15 engines would be needed to match Falcon Heavy performance.
Booster could be full length if thrust-to-weight is acceptable, or shorter if needed, to keep it reasonable.
     Could keep the development focused on a near term achievable goal, while still testing various new technologies. Would test methane GSE, autogenous pressurization, mount landing, carbon fiber tanks and transport of 9 meter vehicles. Could potentially load propellants at standard vs sub-cooled to start.
     This would make the transition smoother, allowing transition to full focus on the BFR after the booster is in service.

[sanman]

The answer is F9 reuse. Once a significant majority of Falcon launches are on used boosters, they can slow production to a crawl an move most of those resources to the BFR factory.. Right now they can't make and test Falcon boosters fast enough.

If this pivot maneuver works, I wonder if Musk/SpaceX will be able to pull this same kind of maneuver all over again down the road, pivoting in the same way from BFR to EvenBiggerBFR (12m or whatever)

There'll always be a bigger rocket in the back of the imagination...

[envy887]

The answer is F9 reuse. Once a significant majority of Falcon launches are on used boosters, they can slow production to a crawl an move most of those resources to the BFR factory.. Right now they can't make and test Falcon boosters fast enough.

If this pivot maneuver works, I wonder if Musk/SpaceX will be able to pull this same kind of maneuver all over again down the road, pivoting in the same way from BFR to EvenBiggerBFR (12m or whatever)

There'll always be a bigger rocket in the back of the imagination...

If BFR works as well as expected, there will be a lot of companies and countries building similar systems, and there will be a lot more money readily available to build a new, bigger system. Once both the business case and technical viability are proven, it gets far easier.

[nacnud]

If this pivot maneuver works, I wonder if Musk/SpaceX will be able to pull this same kind of maneuver all over again down the road, pivoting in the same way from BFR to EvenBiggerBFR (12m or whatever)

There'll always be a bigger rocket in the back of the imagination...

Yes, probably, but the change won't be as dramatic as from partly expendable to fully reuseable. That is the big shift with BFR, not the 9m 12m whatever.

[wannamoonbase]

If the rockets are going to be built at the launch site, why not make them wider and shorter?

The thermal losses on the tanks would be reduced with a decrease in surface area.

[nacnud]

Maybe for the follow on but they are stuck at 9m for the BFR

[jpo234]

     What about building a version of the booster first, but use it to launch the existing Falcon 2nd stage and fairing?

Just no. This doesn't make sense on any level.

[envy887]

     What about building a version of the booster first, but use it to launch the existing Falcon 2nd stage and fairing?

Just no. This doesn't make sense on any level.

They are going to build the upper stage first, per Elon's schedule from last year. And they are going to test it first. I imagine the testing will involve suborbital flights and EDL tryouts, to make sure they can get it back. Then on to an all-up test launch.

[philw1776]

     What about building a version of the booster first, but use it to launch the existing Falcon 2nd stage and fairing?

Just no. This doesn't make sense on any level.

They are going to build the upper stage first, per Elon's schedule from last year. And they are going to test it first. I imagine the testing will involve suborbital flights and EDL tryouts, to make sure they can get it back. Then on to an all-up test launch.

A side benefit is that they need just a couple Raptors for the first test flights.  Get some engine flight data.  Implement some ECOs.  Add extra up-reved SL Raptors.  Fly again. 
Note that an upper stage can't take off even a quarter fueled with just two sea level Raptors.
They get to test out the flight profile of high tech stage 2 without amassing dozens of out of revision Raptors that testing the 1st stage core first could lead to. 
I think they will also most likely first fly stage one itself with less than 31 engines a few times.

[envy887]

     What about building a version of the booster first, but use it to launch the existing Falcon 2nd stage and fairing?

Just no. This doesn't make sense on any level.

They are going to build the upper stage first, per Elon's schedule from last year. And they are going to test it first. I imagine the testing will involve suborbital flights and EDL tryouts, to make sure they can get it back. Then on to an all-up test launch.

A side benefit is that they need just a couple Raptors for the first test flights.  Get some engine flight data.  Implement some ECOs.  Add extra up-reved SL Raptors.  Fly again. 
Note that an upper stage can't take off even a quarter fueled with just two sea level Raptors.
They get to test out the flight profile of high tech stage 2 without amassing dozens of out of revision Raptors that testing the 1st stage core first could lead to. 
I think they will also most likely first fly stage one itself with less than 31 engines a few times.

Quarter-fueled is enough to get to around Mach 8 and several hundred km apogee. Good enough for hypersonic entry testing.

[philw1776]

     What about building a version of the booster first, but use it to launch the existing Falcon 2nd stage and fairing?

Just no. This doesn't make sense on any level.

They are going to build the upper stage first, per Elon's schedule from last year. And they are going to test it first. I imagine the testing will involve suborbital flights and EDL tryouts, to make sure they can get it back. Then on to an all-up test launch.

A side benefit is that they need just a couple Raptors for the first test flights.  Get some engine flight data.  Implement some ECOs.  Add extra up-reved SL Raptors.  Fly again. 
Note that an upper stage can't take off even a quarter fueled with just two sea level Raptors.
They get to test out the flight profile of high tech stage 2 without amassing dozens of out of revision Raptors that testing the 1st stage core first could lead to. 
I think they will also most likely first fly stage one itself with less than 31 engines a few times.

Quarter-fueled is enough to get to around Mach 8 and several hundred km apogee. Good enough for hypersonic entry testing.

Yes.
I also think they may fly with additional SL Raptors replacing a couple Rvacs for some later higher energy test flights

[rsdavis9]

The hardest asset to acquire is experience personnel. The resource Musk was talking about is the F9 production line personnel not tooling, money or even floor space.

By swapping some experienced personnel from the F9 line onto a limited BFR production by replacing them on the F9 line with new hires, spaceX will be able to get the BFR line started rolling slowly. Once the BFR line needs to ramp up which should immediately follow a successful BFR demo flight The F9 line will ramp down and the BFR line will ramp up as more and more personnel transition. In order to do this both lines have to be fairly close (can be separate buildings but in same city) because relocation costs of a few thousand employees is very expensive.

I would suggest that we already have almost all the R+D people transitioned to BFR. They should have finished the block 5. There will be some left for dragon 2...