Author Topic: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 4)  (Read 183053 times)

Offline Chris Bergin

Fourth thread for the Falcon 9 v1.1 discussion and updates (not enough "news" for an update standalone thread).

Thread 1:
http://forum.nasaspaceflight.com/index.php?topic=28882.0

Thread 2:
http://forum.nasaspaceflight.com/index.php?topic=31514.0

Thread 3:
http://forum.nasaspaceflight.com/index.php?topic=31734.0

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Remember, this is a big forum. There are lots of threads. You can start a thread if you have a splinter discussion.

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Offline sanman

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 4)
« Reply #1 on: 10/02/2013 05:36 pm »
So here's a link to the SpaceX site, featuring images of what Falcon9 and FalconHeavy are supposed to look like:

http://www.spacex.com/about/capabilities

So those "chevron" shapes at the bottom of each are supposed to be the landing legs, right?

How come they look so different than the landing legs on the Grasshopper? How come they look like chevrons? Is that supposed to make them more streamlined and aerodynamic?

Are these chevrons what will stop the aero roll forces to stabilize the vehicle and prevent the fuel centrifugation?

Offline JAC

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 4)
« Reply #2 on: 10/02/2013 08:03 pm »
Elon says many things, but what has he really said about turn-around time for a reusable vehicle? Has he really said hours, or is that just a rumor?
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Offline guckyfan

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 4)
« Reply #3 on: 10/02/2013 08:21 pm »
Elon says many things, but what has he really said about turn-around time for a reusable vehicle? Has he really said hours, or is that just a rumor?

For what it's worth I remember only the term "fully and rapidly reusable".

IMO one week would still be "rapidly".

Offline AdamH

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Offline sanman

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 4)
« Reply #5 on: 10/02/2013 08:54 pm »
So does that mean no re-inspection required? Just fuel it up again and go?

Surely there would have to be some minimum inspection requirements between launches.

Offline malu5531

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 4)
« Reply #6 on: 10/02/2013 09:15 pm »
So does that mean no re-inspection required? Just fuel it up again and go?

Surely there would have to be some minimum inspection requirements between launches.

Yes, I think it's safe to assume there would likely be some inspections. Compare with airplanes where ground crew inspect/repair and then pilot doing final preflight inspection.

I think SpaceX will iteratively improve F9R as they learn the weakest links; so in a few years the F9 v1.9, or whatever, is already designed and tested to withstand the wear and tear of thousands of launches, like airplanes, or as close to this vision as possible.

It's probably not going to be easy, but that's not why Elon is doing this. :)

Offline JAC

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 4)
« Reply #7 on: 10/02/2013 09:21 pm »
He has stated "single-digit hours" in the past.

Source: http://www.popularmechanics.com/science/space/rockets/elon-musk-on-spacexs-reusable-rocket-plans-6653023
Safing the craft after cooling down. Picking it up and trucking it to launchpad at least some short distance away. Fixing it to launchpad. Place new second stage on top. Place new payload on top. Refuel.

All in less than 10 hours? Now that is a challenge.
The machine works well.

Offline Elvis in Space

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 4)
« Reply #8 on: 10/02/2013 09:23 pm »
So here's a link to the SpaceX site, featuring images of what Falcon9 and FalconHeavy are supposed to look like:

http://www.spacex.com/about/capabilities

So those "chevron" shapes at the bottom of each are supposed to be the landing legs, right?

How come they look so different than the landing legs on the Grasshopper? How come they look like chevrons? Is that supposed to make them more streamlined and aerodynamic?

Are these chevrons what will stop the aero roll forces to stabilize the vehicle and prevent the fuel centrifugation?

Grasshopper is a test article for practicing landings. It's not a flight vehicle.
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Offline Joffan

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 4)
« Reply #9 on: 10/02/2013 09:28 pm »

Safing the craft after cooling down. Picking it up and trucking it to launchpad at least some short distance away. Fixing it to launchpad. Place new second stage on top. Place new payload on top. Refuel.

All in less than 10 hours? Now that is a challenge.

Surprising things sometimes happen when you set difficult targets.
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Online docmordrid

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 4)
« Reply #10 on: 10/02/2013 09:51 pm »
"Everything is theoretically impossible, until it is done."
--Robert A. Heinlein

....and I get the feeling there are a lot of Heinlein fans at SpaceX.
« Last Edit: 10/02/2013 09:53 pm by docmordrid »
DM

Offline guckyfan

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 4)
« Reply #11 on: 10/02/2013 09:56 pm »
A lot will depend on payload integration. That too needs to become much easier for fast turnaround.

Depends on the kind of payload too. Fuel can be integrated quickly using a pump. ;D

If you fly a tanker.


Offline meekGee

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 4)
« Reply #12 on: 10/02/2013 11:29 pm »
He has stated "single-digit hours" in the past.

Source: http://www.popularmechanics.com/science/space/rockets/elon-musk-on-spacexs-reusable-rocket-plans-6653023
Safing the craft after cooling down. Picking it up and trucking it to launchpad at least some short distance away. Fixing it to launchpad. Place new second stage on top. Place new payload on top. Refuel.

All in less than 10 hours? Now that is a challenge.

For rapid flight rate, IMO:

- The rocket never goes horizontal.
- The second stage and the payload are pre-integrated.
- If the integration procedure is very simple and involve only a handful of people, you don't need to safe the first stage.  Imagine that the processing crew has just as many people as the safing team.  You only safe something if it's about to be handled by a larger population.  But if it's about to launch again tomorrow, what's the point?
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Offline aero

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 4)
« Reply #13 on: 10/02/2013 11:54 pm »
I don't think the really rapid turn-around would apply to the case where each payload required a custom mission. Rather, consider something like a fuel tanker. Given several identical, easy payload integration missions in sequence, then it becomes a matter of the needs of the rocket.

Of course your point of having integrated payload/second stages waiting results in the same thing.

Of course, if you extrapolate the <10 hr. turn-around to months and years, then what possible payloads would require that many launches? Dare I say it? "people"
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Offline meekGee

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 4)
« Reply #14 on: 10/02/2013 11:58 pm »
I don't think the really rapid turn-around would apply to the case where each payload required a custom mission. Rather, consider something like a fuel tanker. Given several identical, easy payload integration missions in sequence, then it becomes a matter of the needs of the rocket.


I totally agree.

I'm thinking of (in addition to fuel tankers):
- Standardized cargo landers for a Mars colony
- Manned Dragons (Orbital space tourism might happen, even though SpaceX is not chasing it)

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Offline Elmar Moelzer

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 4)
« Reply #15 on: 10/03/2013 12:00 am »
I am pretty sure that the second stage will need more service time than a first stage. The TPS needs inspected and potentially replaced and the payload needs to be integrated with it. As meekGee suggested, they could have mutiple second stages waiting and preintegrated with the payload for the next launches.

Offline ArbitraryConstant

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 4)
« Reply #16 on: 10/03/2013 12:06 am »
I don't think random satellites could achieve rapid turnaround on that scale, but a well understood payload like Dragon probably could (or standard Mars module).

Offline ChrisWilson68

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 4)
« Reply #17 on: 10/03/2013 01:44 am »
I am pretty sure that the second stage will need more service time than a first stage. The TPS needs inspected and potentially replaced and the payload needs to be integrated with it. As meekGee suggested, they could have mutiple second stages waiting and preintegrated with the payload for the next launches.

Yes, the second stage is likely not to have nearly as fast a turnaround time as the first, at least for a very long time.

In the near term, the second stage won't even be reused while the first will.

When the second stage is first reused, it's likely going to be using technology from Dragon, including the PICA-X heat shield.  PICA-X is ablative, so you need to replace it, at least after a few flights.  PICA-X is designed to be cheap, so that should be OK for a while.

Eventually, if reusability is going really well and SpaceX finds it would be useful to make second-stage reuse even faster and cheaper, they might replace the PICA-X with some sort of non-ablative heat shield.  Certain kinds of non-ablative metallic heat shields seem possible, though they're definitely a challenge, and might have mass penalties that would make them not worth doing.  At any rate, that's far in the future.

I don't think random satellites could achieve rapid turnaround on that scale, but a well understood payload like Dragon probably could (or standard Mars module).

Yeah, or a propellant tanker (possibly based on Dragon, but optimized for automated delivery of propellant to depots or spacecraft).

For random satellites, someday they might be boxed up for shipment, delivered to a station in orbit, and unpacked and inspected there.  If something is wrong, they might ship up replacement components, or send the whole satellite back to the ground for repairs.  When it's ready to go, it can be put on a SEP tug for a low-G trip it to the desired orbit.

Edited to fix the wording.
« Last Edit: 10/03/2013 01:46 am by ChrisWilson68 »

Offline Elmar Moelzer

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 4)
« Reply #18 on: 10/03/2013 03:11 am »
I am pretty sure that the second stage will need more service time than a first stage. The TPS needs inspected and potentially replaced and the payload needs to be integrated with it. As meekGee suggested, they could have mutiple second stages waiting and preintegrated with the payload for the next launches.

Yes, the second stage is likely not to have nearly as fast a turnaround time as the first, at least for a very long time.

In the near term, the second stage won't even be reused while the first will.

When the second stage is first reused, it's likely going to be using technology from Dragon, including the PICA-X heat shield.  PICA-X is ablative, so you need to replace it, at least after a few flights.  PICA-X is designed to be cheap, so that should be OK for a while.

Eventually, if reusability is going really well and SpaceX finds it would be useful to make second-stage reuse even faster and cheaper, they might replace the PICA-X with some sort of non-ablative heat shield.  Certain kinds of non-ablative metallic heat shields seem possible, though they're definitely a challenge, and might have mass penalties that would make them not worth doing.  At any rate, that's far in the future.

Yeah, first stage reuse is easier and more important. The second stage has unique challenges, the heat shield being only one of them. Musk once said that the heatshield oin Dragon can probably be reused many times. I expect the same for the PICA-X on the US. Even if it is not, the simple shape allows for large tiles that can probably be replaced very quickly. So I do not really see that big of an issue with that.

Offline savuporo

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 4)
« Reply #19 on: 10/03/2013 03:16 am »
IMO one week would still be "rapidly".

Expendable orbital launchers have demonstrated sustained weekly turnaround, so its hard to see how reusable turned around in a week would be much of an improvement.
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