Author Topic: SpaceX Texas launch site Discussion and Updates - Thread 5  (Read 166418 times)

Offline rsdavis9

Thought experiment: If the BFR is as reliable as hoped, at what point would it be allowed to over fly land? On a nominal launch it will be 100% reusable so won't drop anything intentionally. I drive under low flying A380s and 747s regularly, as do millions, but if one of those fell out of the sky things would dramatic fast. If allowed to fly over land then the need for multiple launch sites, and multiple boosters recedes. 

Thoughts?

If they allow for overflight of cuba and the yucatan they can get a wide range of azimuths. It looks like 0 deg for straight east and maybe 60 degrees for southeast.
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Online gongora

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Re: SpaceX Texas launch site Discussion and Updates - Thread 5
« Reply #581 on: 10/12/2017 05:39 PM »
Thought experiment: If the BFR is as reliable as hoped, at what point would it be allowed to over fly land? On a nominal launch it will be 100% reusable so won't drop anything intentionally. I drive under low flying A380s and 747s regularly, as do millions, but if one of those fell out of the sky things would dramatic fast. If allowed to fly over land then the need for multiple launch sites, and multiple boosters recedes. 

Thoughts?

There are numerous BFR threads.  They would be a more appropriate place for that thought.

Online jpo234

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Re: SpaceX Texas launch site Discussion and Updates - Thread 5
« Reply #582 on: 10/12/2017 05:55 PM »
Thought experiment: If the BFR is as reliable as hoped, at what point would it be allowed to over fly land? On a nominal launch it will be 100% reusable so won't drop anything intentionally. I drive under low flying A380s and 747s regularly, as do millions, but if one of those fell out of the sky things would dramatic fast. If allowed to fly over land then the need for multiple launch sites, and multiple boosters recedes. 

Thoughts?

If they allow for overflight of cuba and the yucatan they can get a wide range of azimuths. It looks like 0 deg for straight east and maybe 60 degrees for southeast.
Would they be over the Kármán line at this point? Otherwise they would enter Cuban or Mexican air space...
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Online acsawdey

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Re: SpaceX Texas launch site Discussion and Updates - Thread 5
« Reply #583 on: 10/12/2017 06:10 PM »
If they allow for overflight of cuba and the yucatan they can get a wide range of azimuths. It looks like 0 deg for straight east and maybe 60 degrees for southeast.
Would they be over the Kármán line at this point? Otherwise they would enter Cuban or Mexican air space...

Doesn't this have more to do with the path traced out by the instantaneous impact point during the flight?

Online envy887

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Re: SpaceX Texas launch site Discussion and Updates - Thread 5
« Reply #584 on: 10/12/2017 06:18 PM »
If they allow for overflight of cuba and the yucatan they can get a wide range of azimuths. It looks like 0 deg for straight east and maybe 60 degrees for southeast.
Would they be over the Kármán line at this point? Otherwise they would enter Cuban or Mexican air space...

Doesn't this have more to do with the path traced out by the instantaneous impact point during the flight?

The upper stage would reach 100 km altitude while only 100 to 200 km from the launch site, so that's not an issue.

But yes, the issue is IIP trace, especially over populated areas.

Offline rsdavis9

Doesn't every launch from the cape going east have a IIP of in europe or africa at some point in the flight?
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Offline kaoru

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Re: SpaceX Texas launch site Discussion and Updates - Thread 5
« Reply #586 on: 10/12/2017 07:15 PM »
If they allow for overflight of cuba and the yucatan they can get a wide range of azimuths. It looks like 0 deg for straight east and maybe 60 degrees for southeast.
Would they be over the Kármán line at this point? Otherwise they would enter Cuban or Mexican air space...

Doesn't this have more to do with the path traced out by the instantaneous impact point during the flight?

The upper stage would reach 100 km altitude while only 100 to 200 km from the launch site, so that's not an issue.

But yes, the issue is IIP trace, especially over populated areas.

It makes sense to fly only BFR out of Boca Chica because the intent is to make BFR as reliable as an aircraft.  If this is achieved then flying over populated areas like Cuba (at an altitude > 100km) should be ok.  BFS won't have an AFTS/FTS system on board and BFR will safe its AFTS after meco/separation of BFS.  This means that the rule about flying over populated areas would be moot since there shouldn't be a possibly of impact (unless in an accident like aircraft today).

Offline Jim

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Re: SpaceX Texas launch site Discussion and Updates - Thread 5
« Reply #587 on: 10/12/2017 07:28 PM »

The upper stage would reach 100 km altitude while only 100 to 200 km from the launch site, so that's not an issue.

But yes, the issue is IIP trace, especially over populated areas.

It makes sense to fly only BFR out of Boca Chica because the intent is to make BFR as reliable as an aircraft.  If this is achieved then flying over populated areas like Cuba (at an altitude > 100km) should be ok.  BFS won't have an AFTS/FTS system on board and BFR will safe its AFTS after meco/separation of BFS.  This means that the rule about flying over populated areas would be moot since there shouldn't be a possibly of impact (unless in an accident like aircraft today).

Like he said,it has nothing do with the altitude when flying over.  It has to do with the IIP trace.  And if the IIP trace has not reached the populated areas like Cuba (which the vehicle will eventually fly over) until after staging, then the BFS WILL have an AFTS/FTS system

Offline kaoru

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Re: SpaceX Texas launch site Discussion and Updates - Thread 5
« Reply #588 on: 10/12/2017 08:14 PM »

The upper stage would reach 100 km altitude while only 100 to 200 km from the launch site, so that's not an issue.

But yes, the issue is IIP trace, especially over populated areas.

It makes sense to fly only BFR out of Boca Chica because the intent is to make BFR as reliable as an aircraft.  If this is achieved then flying over populated areas like Cuba (at an altitude > 100km) should be ok.  BFS won't have an AFTS/FTS system on board and BFR will safe its AFTS after meco/separation of BFS.  This means that the rule about flying over populated areas would be moot since there shouldn't be a possibly of impact (unless in an accident like aircraft today).

Like he said,it has nothing do with the altitude when flying over.  It has to do with the IIP trace.  And if the IIP trace has not reached the populated areas like Cuba (which the vehicle will eventually fly over) until after staging, then the BFS WILL have an AFTS/FTS system

Did the space shuttle have a FTS?  I don't have any specific knowledge of regarding the use of FTS on a crewed (astronauts assuming risk) vehicle with no LAS/LES but it certainly sounds like a bad idea.  Putting in a flight termination system in BFR/BFS carrying *civilian* passengers with no LES capabilities seems beyond stupid.

I understand why no LES capability is part of the BFR/BFS design (for margins and such) and "reliability" of BFR/BFS is the answer to passenger safety (in lieu of LES/LAS).  This makes sense if the reliability is proven, aka BFR/BFS is as safe as an aircraft (i.e. A380).

How I interpret things, BFS is essentially an oversized F9 S2 permanently attached to oversized CC Dragon (minus any Super Dracos/LAS) for carrying way more crew/passengers.  This makes BFS essentially the same as CC Dragon from a flight termination POV.  Current CC Dragon doesn't have a FTS system, so why should the BFS?  If a FTS is required, it'll be interesting to read the indemnity waiver for the passengers... "SpaceX is not responsible for your death if the spacecraft decides to blow itself up on the off chance it might hit an island in a large ocean"...
« Last Edit: 10/12/2017 08:22 PM by kaoru »

Online cppetrie

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SpaceX Texas launch site Discussion and Updates - Thread 5
« Reply #589 on: 10/12/2017 08:29 PM »
Shuttle had FTS. Bob Cabana talked about it during the press conference when AFTS moved to primary on Falcon.

FTS is about public safety. Sure, killing the crew isn’t good. But having the rocket crash and kill many members of the public is considered worse. The general public didn’t sign up to sit on the rocket. The astronauts did.

Edit: added some additional thoughts
« Last Edit: 10/12/2017 08:32 PM by cppetrie »

Online envy887

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Re: SpaceX Texas launch site Discussion and Updates - Thread 5
« Reply #590 on: 10/12/2017 08:41 PM »
Doesn't every launch from the cape going east have a IIP of in europe or africa at some point in the flight?

Yes, the trace goes all the way around the world in the time it takes to raise perigee above the surface - usually about 8 minutes. Close to the launch site, it moves very slowly, but further away it's moving very quickly, so the probability of a vehicle breakup resulting in expected casualties far downrange is quite low. The IIP crosses the thousands of miles of Africa in only a few seconds.

The expected casualties number is basically a function of vehicle reliability and vehicle mass integrated over time along the population along the IIP trace. Per the FAA, the number of expected casualties has to be lower than 30x10^-6 per launch.

Online envy887

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Re: SpaceX Texas launch site Discussion and Updates - Thread 5
« Reply #591 on: 10/12/2017 08:46 PM »
...
How I interpret things, BFS is essentially an oversized F9 S2 permanently attached to oversized CC Dragon (minus any Super Dracos/LAS) for carrying way more crew/passengers.  This makes BFS essentially the same as CC Dragon from a flight termination POV.  Current CC Dragon doesn't have a FTS system, so why should the BFS?  If a FTS is required, it'll be interesting to read the indemnity waiver for the passengers... "SpaceX is not responsible for your death if the spacecraft decides to blow itself up on the off chance it might hit an island in a large ocean"...

The BFS will be operated autonomously and needs AFTS for those flights, for certain. If something goes wrong it's basically a 1,000 ton unmanned flying bomb.

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Re: SpaceX Texas launch site Discussion and Updates - Thread 5
« Reply #592 on: 10/12/2017 09:06 PM »
Doesn't every launch from the cape going east have a IIP of in europe or africa at some point in the flight?

Yes, the trace goes all the way around the world in the time it takes to raise perigee above the surface - usually about 8 minutes. Close to the launch site, it moves very slowly, but further away it's moving very quickly, so the probability of a vehicle breakup resulting in expected casualties far downrange is quite low. The IIP crosses the thousands of miles of Africa in only a few seconds.

The expected casualties number is basically a function of vehicle reliability and vehicle mass integrated over time along the population along the IIP trace. Per the FAA, the number of expected casualties has to be lower than 30x10^-6 per launch.
I figure that in addition to the rapid motion of the IIP, the probably breakup of the stage due to the near orbital speed uncontrolled reentry at that point also would help reduce the expected casualties.

I have wondered about this before though, is there a rule of thumb for how far away a land overflight has to be before these factors sufficiently reduce the expected casualty count so that overflight is reasonable?

Could BFR use a more lofted trajectory to make the IIP pass over Cuba or the Yucatan more quickly and allow these overflights? Suggesting lofted trajectory because the higher you are (longer before your ballistic arc hits the ground), the further a set amount of horizontal delta V will move your IIP.

Offline kaoru

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SpaceX Texas launch site Discussion and Updates - Thread 5
« Reply #593 on: 10/12/2017 09:17 PM »
Shuttle had FTS. Bob Cabana talked about it during the press conference when AFTS moved to primary on Falcon.

FTS is about public safety. Sure, killing the crew isn’t good. But having the rocket crash and kill many members of the public is considered worse. The general public didn’t sign up to sit on the rocket. The astronauts did.

Edit: added some additional thoughts
I agree that NASA astronauts signed up...  But BFS will transport regular public (eventually) like an aircraft of which FAA ensures safety for all.  Somehow I don't think the FAA will allow the guaranteed death of a hundred passengers to *probably* save an unknown quantity of people/things on the ground.  That's why aircraft don't have FTS...
« Last Edit: 10/12/2017 09:19 PM by kaoru »

Offline kaoru

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Re: SpaceX Texas launch site Discussion and Updates - Thread 5
« Reply #594 on: 10/12/2017 09:23 PM »
...
How I interpret things, BFS is essentially an oversized F9 S2 permanently attached to oversized CC Dragon (minus any Super Dracos/LAS) for carrying way more crew/passengers.  This makes BFS essentially the same as CC Dragon from a flight termination POV.  Current CC Dragon doesn't have a FTS system, so why should the BFS?  If a FTS is required, it'll be interesting to read the indemnity waiver for the passengers... "SpaceX is not responsible for your death if the spacecraft decides to blow itself up on the off chance it might hit an island in a large ocean"...

The BFS will be operated autonomously and needs AFTS for those flights, for certain. If something goes wrong it's basically a 1,000 ton unmanned flying bomb.
That's an absolute given...  My comments are directed at BFS flying from Boca Chica over Cuba with civilian passengers only.  The BFR could have AFTS if BFS can use its SL Raptors as LES.  The BFS would have no AFTS obviously.

Offline Herb Schaltegger

Shuttle had FTS. Bob Cabana talked about it during the press conference when AFTS moved to primary on Falcon.

FTS is about public safety. Sure, killing the crew isn’t good. But having the rocket crash and kill many members of the public is considered worse. The general public didn’t sign up to sit on the rocket. The astronauts did.

Edit: added some additional thoughts
I agree that NASA astronauts signed up...  But BFS will transport regular public (eventually) like an aircraft of which FAA ensures safety for all.  Somehow I don't think the FAA will allow the guaranteed death of a hundred passengers to *probably* save an unknown quantity of people/things on the ground.  That's why aircraft don't have FTS...

How much experience do you have with how the US federal government promulgates regulations for new and emerging areas? If the answer is anything but "Lots," then I respectfully suggest you - and every other armchair amateur rocket scientist/lawyer - stick to regulations as they exist now, and technologies such as AFTS that exist now - rather than make blanket pronouncements about future PowerPoint vehicles servicing future PowerPoint economic markets that do not yet exist.
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« Last Edit: 10/13/2017 01:19 AM by SPITexas »

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Re: SpaceX Texas launch site Discussion and Updates - Thread 5
« Reply #597 on: 10/13/2017 01:37 AM »
There are numerous BFR threads.  They would be a more appropriate place for that thought.

Not really, I was interested in the flight path of BFR specifically from Boca Chica as given the news from the last few days it is possible that it will be the initial launch site, this a discussion thread too. :)

It would be interesting to take a step back from FAA rules and flight termination systems and think in terms of insurers liabilities and how to mitigate risk. Then go back and see how FAA rules etc. apply.

Online Dave G

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Re: SpaceX Texas launch site Discussion and Updates - Thread 5
« Reply #598 on: 10/13/2017 02:13 AM »
In addition various reddit comments from Gwynne Shotwell's talk and Q&A last night say that the Boca Chica site is now specifically for BFR.

That's not how I read it.

The exact quote from reddit was:
"she VERY specifically said that the Texas launch site was for the BFR. The BFR will launch from there."

Reading this, it seems it's Gwynne's statement that's specific, not the launch site.

In other words, we don't know whether Falcon 9 will launch from Boca Chica or not. We only know that that BFR will launch from there, someday, assuming they can get approval to do so.

« Last Edit: 10/13/2017 02:32 AM by Dave G »

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Re: SpaceX Texas launch site Discussion and Updates - Thread 5
« Reply #599 on: 10/13/2017 02:30 AM »
http://us.blastingnews.com/news/2017/10/spacexs-gwynne-shotwell-reveals-more-details-about-the-bfr-002085099.html

Is Texas really SpaceX first & final choice to launch the BFR. First.

From the article you linked:
Quote
Shotwell did not provide any detail about how the Boca Chica spaceport would handle BFR launches and landings, whether they would be from land or, as some illustrations suggest, from an offshore platform.

Texas has plenty of firms with expertise in building offshore platforms. Launching from offshore would likely avoid the issue of beach closures that land launches have entailed.

Note that we've previously discussed the possibility of a BFR launch pad a few miles offshore from Boca Chica, starting around here.

An offshore pad combined with an onshore control center, tracking station, and propellant storage could make getting approvals a lot easier.
« Last Edit: 10/13/2017 02:36 AM by Dave G »

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