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Skylon

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44 minutes ago, Jaff said:

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 

 Because SpaceX is a US-based company, same reason Rocket Lab needs FAA approval to launch from New Zealand. 

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5 minutes ago, CatastrophicFailure said:

 Because SpaceX is a US-based company, same reason Rocket Lab needs FAA approval to launch from New Zealand. 

Ok, if there’s no way around that, why does nasa have to get involved? 

I imagine FAA are a lot easier to get approval from than nasa 

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1 hour ago, sevenperforce said:

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.

Maybe this is the math Shotwell has done.

I don't see P2P as being terribly likely, mostly from a safety standpoint, but I can only assume Shotwell has run numbers that they have internally.

1 hour ago, sevenperforce said:

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.

Maybe this is the math Shotwell has done.

I don't see P2P as being terribly likely, mostly from a safety standpoint, but I can only assume Shotwell has run numbers that they have internally.

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47 minutes ago, Jaff said:

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

The boat could be a separate fare, and I did mention "costs associated with providing a passenger terminal/boarding passengers etc".

47 minutes ago, Jaff said:

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 

SpaceX is an American corporation, who will presumably want to remain based in America, and sell tickets in America, and to Americans.  (Not to mention keep launching US defence and national security payloads).  I'm far from an expert, but I believe doing those things will require appropriate licenses from the FAA.  As a US corporation I think that they need those licenses even if they are launching from international waters. 

Getting those licences will almost certainly require rewriting or waiving some of the FAA's existing rules that are written for airplanes, and which make no sense for something like BFR.  There will almost certainly be opposition from Boeing, Airbus and established airlines to licencing BFR for commercial flights, since that could eat into their profits.  They will almost certainly argue that BFR isn't as safe as an airplane.  eg. They will probably argue that even if an airplane loses all it's engines it can still glide and potentially land safely.  As I understand the BFR design, if it loses all it's engines, it can't land, and will crash.   If Nasa refuses to human-rate BFR, then Boeing and Airbus will use that as a powerful argument, saying NASA doesn't consider it safe, so the FAA shouldn't consider it safe.  They same arguments will apply if they try to get any other aviation body to approve it for flight. 

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1 hour ago, Jaff said:

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 

Why would you think that a European regulatory burden would be any easier to meet than an American one? I'd expect it to be worse, if anything.

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21 minutes ago, AVaughan said:

Folding is hopefully faster, and they would probably prefer to have the rocket horizontal and undercover before Florence gets to close.

AFAIK, they've never actually folded them and kept them folded before, they always removed 'em. This would be an encouraging first if they do.

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2 hours ago, sevenperforce said:

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.

1 hour ago, tater said:

Maybe this is the math Shotwell has done.

I don't see P2P as being terribly likely, mostly from a safety standpoint, but I can only assume Shotwell has run numbers that they have internally.

I wonder what would happen to the numbers for launching just the BFS stage from sealevel if you added another sealevel raptor (or several, if that results in overall improved numbers.  Maybe remove some/all of the the vacuum raptors, again if that improves the numbers).  That will give you higher sealevel thrust, and hence the ability to lift a larger fuel load.  (eg the same fuel load as the BFS tanker, and still carry 100 passengers).  Perhaps stretch the fuel tanks into some of BFS's cargo/Mars crew accommodations.  (You don't need kitchens/showers/personal cabins/rec areas for 100 passengers for a sub-orbital hop.  Life support should also be smaller and lighter). 

Edit: Also shorter routes could be practical even if antipodal routes aren't.  eg  New York to Brest or England, San Francisco to Japan. Honolulu to Brisbane/Japan/San Francisco.  Not sure how much less dV that requires compared to antipodal routes (probably not much), but if it allows you to launch just the BFS, then that will reduce fuel + maintenance costs, and should also make terminals smaller and cheaper, and possibly allow them to be built closer to major pop centres.

Edited by AVaughan
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5 hours ago, AVaughan said:

I wonder what would happen to the numbers for launching just the BFS stage from sealevel if you added another sealevel raptor (or several, if that results in overall improved numbers.  Maybe remove some/all of the the vacuum raptors, again if that improves the numbers).  That will give you higher sealevel thrust, and hence the ability to lift a larger fuel load.  (eg the same fuel load as the BFS tanker, and still carry 100 passengers).  Perhaps stretch the fuel tanks into some of BFS's cargo/Mars crew accommodations.  (You don't need kitchens/showers/personal cabins/rec areas for 100 passengers for a sub-orbital hop.  Life support should also be smaller and lighter). 

Edit: Also shorter routes could be practical even if antipodal routes aren't.  eg  New York to Brest or England, San Francisco to Japan. Honolulu to Brisbane/Japan/San Francisco.  Not sure how much less dV that requires compared to antipodal routes (probably not much), but if it allows you to launch just the BFS, then that will reduce fuel + maintenance costs, and should also make terminals smaller and cheaper, and possibly allow them to be built closer to major pop centres.

Yes how far could you go with an upper stage who is SSTO optimized, low cargo weight so you could run more fuel and obliviously you mostly use ground level engines. 
An two stage ballistic launch would be an added issue as this is an obvious weapon system as in rods from the gods, or more fancy one very big rod, yes you had to fold it but that is solvable.

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I had the tweet copied and everything :D

So it's just one person now? Different one, or did the other cancel? I remember the Dragon V2 Moon mission had 2 people. Also, I wonder what the timeline for this mission will be. "Shortly" after the first test flight in the early 2020s? Will we get more news on BFR development on September 17th too? So many questions!

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1 minute ago, .50calBMG said:

Hope thats just an artist rendering for the BFR, not another redesign

It looks like someone took the old 7-engine design for ITS and drew it on a BFS airframe, and then added a Shuttle-style tailfin for good measure. I highly suspect it was produced by a third party that's been out of the loop for a couple of years.

1 minute ago, sh1pman said:

It's on their official twitter though. Previously their artist renderings were accurate.

Oh, wait. Now that you've pointed that out...

This is very strange.

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1 minute ago, IncongruousGoat said:

Oh, wait. Now that you've pointed that out...

This is very strange.

Funny, in my KSP replica of BFR I switched from 2 fins to 3, because it was a bloody nightmare to keep it stable during reentry otherwise.

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