Gwynne Shotwell lecture at Stanford 11 Oct 2017

[high road]

Guys, priorities!

FH still on for this year? As far as we know, her dates are more accurate, no?

[acsawdey]

Entirely possible that you're right, but I'd still suggest checking out the last several pages of this thread. livingjw demonstrates a pretty strong understand of rocket propulsion and backs up those charts and claims with data.

http://forum.nasaspaceflight.com/index.php?topic=41363.msg1733108#msg1733108

I trust John's analysis (and have independently confirmed some of them in RPA). But we've never had a solid source for both the chamber pressure and thrust, even in L2. John says so himself in that thread. Without knowing both values for the same operating configuration it's impossible to know exactly how large the engine is physically or what thrust it would get at the quote chamber pressures.

My interpretation is that the demo engine is physically smaller than Merlin D and gets 1000 kN at 20 bar, and that when Shotwell said they were building a larger Raptor right now, when meant physically larger - not just higher pressure. The larger Raptor will run at 25 bar and get 1700 kN at sea level, but it would also get more than 1000 kN at 20 bar.

But it's also plausible that the demo runs at less than 20 to get 1000 kN, and the larger Raptor is the same physical size and just higher pressure.

You keep saying 20 bar but I think you mean 200 bar, right?

[envy887]

Entirely possible that you're right, but I'd still suggest checking out the last several pages of this thread. livingjw demonstrates a pretty strong understand of rocket propulsion and backs up those charts and claims with data.

http://forum.nasaspaceflight.com/index.php?topic=41363.msg1733108#msg1733108

I trust John's analysis (and have independently confirmed some of them in RPA). But we've never had a solid source for both the chamber pressure and thrust, even in L2. John says so himself in that thread. Without knowing both values for the same operating configuration it's impossible to know exactly how large the engine is physically or what thrust it would get at the quote chamber pressures.

My interpretation is that the demo engine is physically smaller than Merlin D and gets 1000 kN at 20 bar, and that when Shotwell said they were building a larger Raptor right now, when meant physically larger - not just higher pressure. The larger Raptor will run at 25 bar and get 1700 kN at sea level, but it would also get more than 1000 kN at 20 bar.

But it's also plausible that the demo runs at less than 20 to get 1000 kN, and the larger Raptor is the same physical size and just higher pressure.

You keep saying 20 bar but I think you mean 200 bar, right?

Yeah, should be MPa not bar...

[raketa]

1/Elon Ask fast refuel from Tanker BFR to Crew/Cargo BFR.
2/Is it possible, if BFR Crew/Cargo is on high elliptical orbit, could quickly meet in low part orbit and refuels.
3/Could  tanker save fuel not to go high elliptical orbit, but match speed for short time?

[192]

1/Elon Ask fast refuel from Tanker BFR to Crew/Cargo BFR.
2/Is it possible, if BFR Crew/Cargo is on high elliptical orbit, could quickly meet in low part orbit and refuels.
3/Could  tanker save fuel not to go high elliptical orbit, but match speed for short time?

If you have matched speed and position, you are in the same orbit and have already spent the fuel. As to saving time by meeting in the low part of the orbit, while theoretically possible, this would involve using lots of fuel at perigee to greatly reduce apogee rather than a little fuel at apogee to slightly reduce perigee and so would be highly inefficient. Any HEO tanker mission will therefore complete at least one orbit.

[vaporcobra]

Entirely possible that you're right, but I'd still suggest checking out the last several pages of this thread. livingjw demonstrates a pretty strong understand of rocket propulsion and backs up those charts and claims with data.

http://forum.nasaspaceflight.com/index.php?topic=41363.msg1733108#msg1733108

I trust John's analysis (and have independently confirmed some of them in RPA). But we've never had a solid source for both the chamber pressure and thrust, even in L2. John says so himself in that thread. Without knowing both values for the same operating configuration it's impossible to know exactly how large the engine is physically or what thrust it would get at the quote chamber pressures.

My interpretation is that the demo engine is physically smaller than Merlin D and gets 1000 kN at 20 bar MPa, and that when Shotwell said they were building a larger Raptor right now, when meant physically larger - not just higher pressure. The larger Raptor will run at 25 bar MPa and get 1700 kN at sea level, but it would also get more than 1000 kN at 20 bar MPa.

But it's also plausible that the demo runs at less than 20 to get 1000 kN, and the larger Raptor is the same physical size and just higher pressure.

It's totally possible. lol we basically disagreed, only to converge! My main point initially was that the "larger" comment almost certainly implies a physically larger Raptor, probably beginning at the 200 bar they're comfortable with and moving to 250 as the tests continue. Roughly pegging the size just by judging it in comparison with the equipment nearby, it is 100% Merlin sized, maybe +/- 20%.

So I agree, plenty of uncertainty. I hope we get some solid Raptor questions answered this weekend

[CT Space Guy]

Does LA stand for Los Angeles or Louisiana for the BFR factory?

[AJW]

Gwynne commented that it would cost SPX as much as $2 Million to transport each BFR to the port of Los Angeles.  This would have involved removing lights, signs, etc., so setting up a facility near the port would save them this expense and they could also bring in the experienced teams from Hawthorne.

[clongton]

Does LA stand for Los Angeles or Louisiana for the BFR factory?

Apparently both. The consensus in another thread is that initially a manufacturing facility will be built in Los Angeles at the docks. The completed BFR will be barged thru the Panama Canal to Boca Chica for test and launch. Later on this will be changed to newer facilities in Louisiana, again on the waterfront. The completed BFR will be barged from there across the gulf to Boca Chica. This will be the permanent facility.

[AdamH]

I've never understood why folks designated some other F-word to the letter 'F'.

It was actually first stated as the F-word by Elon himself, back in 2005 or before. I remember seeing a video where he referenced the BFG 9000 from the video game Doom, but I cannot find it.. Here is something mentioning BFR from 2005:
http://www.thespacereview.com/article/497/1

Then again, it really doesn't matter what the F stands for. Falcon is more appropriate now that SpaceX is more than a tiny, nearly unheard-of, startup.

[Robotbeat]

The likely location of the factory is a small lesson that what Elon says/tweets isn't necessarily what Gwynne Shotwell will enact as company policy!

It also opens up the possibility that the F9 production line will continue to run at least until BFR has entered service.

More like the lesson that SpaceX and Elon can change their mind.

[mme]

Does LA stand for Los Angeles or Louisiana for the BFR factory?

Los Angeles. Elon likes engineering and manufacturing to be close to each other, at least during the development phase.  Once the BFR manufacturing kinks are worked out and if they need to crank up production/flight rate they will build a new factory near the launch pad(s).

[Lars-J]

Does LA stand for Los Angeles or Louisiana for the BFR factory?

Apparently both. The consensus in another thread is that initially a manufacturing facility will be built in Los Angeles at the docks. The completed BFR will be barged thru the Panama Canal to Boca Chica for test and launch. Later on this will be changed to newer facilities in Louisiana, again on the waterfront. The completed BFR will be barged from there across the gulf to Boca Chica. This will be the permanent facility.

No. You are as far as I can tell the only one who thinks that she meant Louisiana.

[meekGee]

In the construction and mechanical trades, sometimes the hammer one has in one's hand isn't producing the desired result, and a bigger hammer is needed. In those trades, the larger hammer is commonly referred to as a "BFH." And the F there does not mean Falcon.

Many video games, especially first-person shooters (like Doom and Quake), have a huge, powerful gun called a "BFG".  Here too, the meaning of the "F" is pretty clear.

And, of course, there is the slang expression "BFD", short for the sarcastic phrase "Big F...... Deal".

More generally, the construction "Big F....... something" is pretty common in popular culture.  So I think it's clear that Elon is just being cheeky calling his rocket the BFR.

I still don't get it.  Can someone please explain the joke yet again?

Edit/Lar: No. No more on this.

[jpo234]

In the construction and mechanical trades, sometimes the hammer one has in one's hand isn't producing the desired result, and a bigger hammer is needed. In those trades, the larger hammer is commonly referred to as a "BFH." And the F there does not mean Falcon.

Many video games, especially first-person shooters (like Doom and Quake), have a huge, powerful gun called a "BFG".  Here too, the meaning of the "F" is pretty clear.

And, of course, there is the slang expression "BFD", short for the sarcastic phrase "Big F...... Deal".

More generally, the construction "Big F....... something" is pretty common in popular culture.  So I think it's clear that Elon is just being cheeky calling his rocket the BFR.

I still don't get it.  Can someone please explain the joke yet again?

From https://www.gq.com/story/elon-musk-mars-spacex-tesla-interview

The rocket that they are working on is referred to internally by the code name BFR. And it doesn't stand for some arcane, smarty-pants science term. It stands for Big frakking Rocket.
...
Musk coined these names himself. "This is a very obtuse video-game reference," he tells me. "In the original Doom, the gun that was like the crazy gun was the BFG 9000 or something like that. So it was sort of named after the gun in Doom. But that's not its official name, of course."

[vanoord]

The likely location of the factory is a small lesson that what Elon says/tweets isn't necessarily what Gwynne Shotwell will enact as company policy!

It also opens up the possibility that the F9 production line will continue to run at least until BFR has entered service.

More like the lesson that SpaceX and Elon can change their mind.

I don't think the two are much more than different ways of looking at it.

Either way, just because Elon tweets something doesn't mean it's going to happen.

Now waiting for the 7.5m BFR...

[Shanuson]

The likely location of the factory is a small lesson that what Elon says/tweets isn't necessarily what Gwynne Shotwell will enact as company policy!

It also opens up the possibility that the F9 production line will continue to run at least until BFR has entered service.

More like the lesson that SpaceX and Elon can change their mind.

I don't think the two are much more than different ways of looking at it.

Either way, just because Elon tweets something doesn't mean it's going to happen.

Now waiting for the 7.5m BFR...

Well more likely to go back to 12m. The current 9m resulted AFAIK from the size that the current Factory could handle. They build a new factory, so that could be sized for any diameter.

[2megs]

Well more likely to go back to 12m. The current 9m resulted AFAIK from the size that the current Factory could handle.

The main goal in my understanding is, "What's small enough to be commercially useful, but big enough to fulfill some of Elon's Mars ambitions without bankrupting the company?"

Going all the way to 12m is doubtful in terms of the business case.

People in other threads here have calculated that the 9m rocket may be too small to launch some GTO payloads with full recovery and without a second tanker launch. If those calculations match reality then going *slightly* bigger could potentially be more profitable, and we may see that. But not 12m bigger until there are paying customers to justify it.

[HIP2BSQRE]

99 percent of the world if you say LA--that means Los Angeles.

[Robotbeat]

If they went 12m, they could just make it shorter and cost about the same.

But they've already ordered tooling, so it's almost certainly ~9m.