Author Topic: General Falcon and Dragon discussion (Thread 13)  (Read 396559 times)

Offline QuantumG

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #100 on: 01/31/2016 09:35 pm »
Welcome to the forum! Great first post. Continuous improvement holds inherent the promise that reliability can be engineered. The alternate view is that it's all just process and procedures. These arguments were made to great effect during the Shuttle era.
Human spaceflight is basically just LARPing now.

Offline alang

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #101 on: 02/02/2016 02:48 am »
"Continuous improvement" may be informed by SpaceX's software culture.
It seems to me that you have to be very confident of your simulations and testing to ever make this work with physical hardware in something as marginal as a rocket stage.
On the other hand I can see how continuois improvement could work with a Marmac barge...
Early days though - I'll be happier when the worries are about how difficult it is to do an engine change.

Offline MikeAtkinson

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #102 on: 02/02/2016 09:45 am »
There are several improvements that SpaceX can make which should keep the price per launch and price per $/kg to LEO and GTO to be reduced over the next decade.

1. Methane second stage (probably 5.2m diameter) using some variant of Raptor.
    Approx 30% payload increase to LEO and perhaps more to GTO. This would mean that F9 could launch all
    current GTO payloads. About the same price as F9 FT.

1a. Reusable methane second stage (probably 5.2m diameter) using some variant of Raptor.
   Some payload improvement to LEO over F9 FT, about the same payload to GTO. Major reduction in cost
   (especially marginal cost).

2. Methane first stage (probably 5.2m diameter) using some variant of Raptor.
   Another 30% performance boost. All current payloads could use RTLS. Can retire FH and barge.
   Now fully reusable it can place about 20 tonnes of payload into LEO.

3. Raptor thrust increase, stage stretch.
   Another 30% performance boost, at no increase in launch cost.
   Now fully reusable it can place about 26 tonnes of payload into LEO.

3a. Second stage with integrated fairing, long duration kit and cis-lunar capability (mini-BFS)

These should keep the SpaceX Falcon team busy for the next 10 years.

Then for Dragon there are several options:

1. 5.2m diameter Dragon (about 3x the volume)
   Dragon is volume limited in many LEO applications, so a larger volume would be very useful, giving 3x the
   cargo capability to a LEO space station for instance.

2. Integrate Dragon with trunk
   Making the trunk reusable.

3. Integrate Dragon with trunk and second stage to form a mini-BFS (1/3 scale, so 1/27 the volume).
   This would be a very capable craft for cis-lunar operations with a crew of up to 20 (30 at a push), and duration
   of a couple of months (volume limited).

3a. Integrate Dragon with trunk and second stage to form a mini-BFS - lunar landing capable.

A big unknown in all this is the tank diameter. 5.2 m has been chosen because it is the same as the current fairing, however I think a slightly larger (6m ?) diameter would be better for long term scalability.

Offline GORDAP

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #103 on: 02/02/2016 10:28 am »
Mike, I'd add:

4. Replace the 3 FH cores with a single stick 5.2 (maybe 6?) meter methane 1st stage, powered by 7-9 Raptors.  Now all launches do RTLS, and no more stage integration.  Full, rapid reusability finally achieved.

Offline MikeAtkinson

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #104 on: 02/02/2016 10:40 am »
Mike, I'd add:

4. Replace the 3 FH cores with a single stick 5.2 (maybe 6?) meter methane 1st stage, powered by 7-9 Raptors.  Now all launches do RTLS, and no more stage integration.  Full, rapid reusability finally achieved.

Already in 2. above "Now can retire FH and barge"

Offline GORDAP

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #105 on: 02/02/2016 10:55 am »
Argh, sorry.  My eyes just skipped over it.

Offline Bynaus

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #106 on: 02/02/2016 02:28 pm »
@Mike: Great post, great ideas (not all of them completely new, but still ;) ). The way you lay it out, it just seems so logical. That doesn't mean of course that SpaceX will follow this path, in particular because they only have limited engineering resources which are likely better spent on the MCT system if they want to keep their goal of Humans to Mars in 2025ish. But then, if they do indeed develop an upper stage with 5.2 m diameter (and I don't think this is a given - it don't even think the Raptor upper stage is a given, despite the DoD contract), the same tooling can easily be re-used for a 5.2 m first stage, with only the sea-level Raptor as a (minimally) new development. It would seem however that such a first stage would be difficult to transport - a short upper stage can be carried by a SuperGuppy as someone has suggested, but a first stage? I can't really see SpaceX renting the Roc to carry them around the country! :)
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Offline sunbingfa

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #107 on: 02/03/2016 06:13 pm »
https://twitter.com/jeff_foust/status/694954313270038528

Spacex plans to re-fly a Dragon this year.....

Offline Geron

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #108 on: 02/04/2016 01:44 am »
Its hard for a SpaceX fan not to have a bit of anxiety about delays after the long delay after the failure in June.

Especially because of the fact that the first Falcon 9 full thrust carried such a light payload. It is great news that SES 9 is possible in the "next couple weeks."

Thank you for sharing this information! My blood pressure just fell about ten points and likely will remain low for fourteen days.

If they don't launch or reserve a time to launch within 14 days its going to start creeping back up again..

Offline Earendil

Re: General Falcon and Dragon discussion (Thread 13)
« Reply #109 on: 02/04/2016 06:56 am »
Well,

Shotwell did say they are making mods based on the 2nd firing of the landed stage. There were speculation on other threads for heat blankets.. but these would have been apparent after the landing, not after the 2nd firing.
So my guess is minor engine tweaks maybe related to the fluctuations they've observed during that firing.

This is the reason for the hold up.. but she seems quite confident that they will build up the pace afterwards.

Moreover she said that from 3 production stands and ability to make about 15 cores per year, they now have 6 stands and will be able to produce up to 30-40 core per year by the end of this one.

So guys.. chill for a couple of weeks :) go for a ski or smth and they'll be back :)

Offline The Amazing Catstronaut

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #110 on: 02/04/2016 07:12 am »
Yes, there's an awful lot of internet "but surely, they will fail" hysteria whenever SpaceX has even the tiniest delays that most other launch service providers experience. Reddit is the primary culprit here.

Minimising that on Nasaspaceflight.com is probably our best way of avoiding heartburn. If something stops it means something is being worked on to increase the likelihood of nominal launches. This is inherently good in itself.

People are fans of the wrong industry if they think it's all about the launches and that anything that detracts from a massive launch cadence is in some way damaging the industry.
Resident feline spaceflight expert. Knows nothing of value about human spaceflight.

Offline e.winsmore

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #111 on: 02/04/2016 08:10 am »
Yes, there's an awful lot of internet "but surely, they will fail" hysteria whenever SpaceX has even the tiniest delays that most other launch service providers experience. Reddit is the primary culprit here.

Minimising that on Nasaspaceflight.com is probably our best way of avoiding heartburn. If something stops it means something is being worked on to increase the likelihood of nominal launches. This is inherently good in itself.

Having lurked on both the r/spacex board and the NSF board for some while, I think both offer some interesting perspectives - realism bordering on optimism, which I don't see a problem with. Crucially, both of these boards seem well informed, more so than say the Facebook group which borders on being unreadable.

I think a lot of it has to do with perspective - no one remembers the huge gulf of delays that plagued SpaceX in 2009-2011. Everyone gets so used to a reasonable launch cadence that was established in 2014 and the early half of 2015, and then suddenly there's a month of delays and people lose their minds, as they try to air their frustrations as a fan.

Offline JamesH

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #112 on: 02/04/2016 09:33 am »
Its hard for a SpaceX fan not to have a bit of anxiety about delays after the long delay after the failure in June.

Especially because of the fact that the first Falcon 9 full thrust carried such a light payload. It is great news that SES 9 is possible in the "next couple weeks."

Thank you for sharing this information! My blood pressure just fell about ten points and likely will remain low for fourteen days.

If they don't launch or reserve a time to launch within 14 days its going to start creeping back up again..

I'm a fan, but don't have any problems with anxiety. I just now that Stuff happens, you need to live with it and accept that some of the best rocket engineers on the planet are working on it. It doesn't affect me directly, and I cannot do anything about it. Delays here and there are not worth getting high blood pressure about!


Offline Jim

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #113 on: 02/04/2016 11:14 am »
Yes, there's an awful lot of internet "but surely, they will fail" hysteria whenever SpaceX has even the tiniest delays that most other launch service providers experience.

It is mostly the other extreme.

Offline Jim

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #114 on: 02/04/2016 11:15 am »

This is the reason for the hold up.. but she seems quite confident that they will build up the pace afterwards.


No, she never said those were the reasons for the hold up

Offline cscott

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #115 on: 02/04/2016 02:34 pm »

This is the reason for the hold up.. but she seems quite confident that they will build up the pace afterwards.


No, she never said those were the reasons for the hold up
I agree with Jim.

We don't even know that the hold up is related to the first stage.  If it is not, then the refire isn't going to bear on it at all.

Also: remember that there was a fuel leak from the vicinity of an engine during the landing attempt (after the reentry burn).  If we're going to read tea leaves, I'd suggest that the "lessons learned" from the refire are more likely to be related to that.  Presumably they repaired the leak before the refire, but perhaps their repair failed to hold up in a surprising way.  If they'd attempted similar repairs pre-launch before, this would be highly relevant to future launch campaigns.
« Last Edit: 02/04/2016 02:35 pm by cscott »

Offline ugordan

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #116 on: 02/04/2016 03:05 pm »
We don't even know that the hold up is related to the first stage.  If it is not, then the refire isn't going to bear on it at all.

That depends on the commonality between stages. For all we know, it could be an S2 issue/vulnerability that was uncovered by the S1 fire.

Offline cscott

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #117 on: 02/04/2016 03:57 pm »


That depends on the commonality between stages. For all we know, it could be an S2 issue/vulnerability that was uncovered by the S1 fire.

Seems like you're piling assumptions on top of each other.  Occam's Razor predicts reality is more likely to be simple.

Besides, we had indications that the SES launch was moving to the right even before the refire.
« Last Edit: 02/04/2016 04:00 pm by cscott »

Offline ugordan

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #118 on: 02/04/2016 04:18 pm »
That depends on the commonality between stages. For all we know, it could be an S2 issue/vulnerability that was uncovered by the S1 fire.

Seems like you're piling assumptions on top of each other.

I'm pointing out that it's you who are assuming no possible connection between 1st stage refire and 2nd stage.

Besides, we had indications that the SES launch was moving to the right even before the refire.

I'll grant you that.

Offline nadreck

Re: General Falcon and Dragon discussion (Thread 13)
« Reply #119 on: 02/04/2016 05:03 pm »
Its hard for a SpaceX fan not to have a bit of anxiety about delays after the long delay after the failure in June.

Especially because of the fact that the first Falcon 9 full thrust carried such a light payload. It is great news that SES 9 is possible in the "next couple weeks."

Thank you for sharing this information! My blood pressure just fell about ten points and likely will remain low for fourteen days.

If they don't launch or reserve a time to launch within 14 days its going to start creeping back up again..

I'm a fan, but don't have any problems with anxiety. I just now that Stuff happens, you need to live with it and accept that some of the best rocket engineers on the planet are working on it. It doesn't affect me directly, and I cannot do anything about it. Delays here and there are not worth getting high blood pressure about!

I was made more "anxious" by the statement that we would get new FH performance numbers soon. I am just as excited to get more information as I am by launches.
It is all well and good to quote those things that made it past your confirmation bias that other people wrote, but this is a discussion board damnit! Let us know what you think! And why!

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