Author Topic: Speculation into what future versions of Dragon will involve  (Read 95056 times)

Offline beancounter

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Re: Speculation into what future versions of Dragon will involve
« Reply #140 on: 12/10/2012 05:17 am »
No the simplest explanation is that Elon's been reading NS forum and has simply decided to throw something out there to see what we all think :)
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Online meekGee

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Re: Speculation into what future versions of Dragon will involve
« Reply #141 on: 12/10/2012 06:01 am »
They didn't call it v1.1 or v1.5.  They called it 2.0, and I think this means that went back and designed it from scratch.

Sigh... In other words, you ignore what evidence is out there (CCiCap, statements by informed people like Jim) and decide to make stuff up. Well, prepare to be disappointed.

And BTW, since you seem to care so much about determining meaning in numerology - I believe Musk called in "Dragon 2", not "Dragon 2.0". There is a fine difference there, if you care to see it.

Seriously - the version # is the least important bit in that post... 

And what evidence are you talking about that I'm supposedly ignoring? That the pressure vessel hasn't changed?  I'd love to hear about any such evidence, one way or the other, since just like the rest of us here, I don't know....

But how about the rest of my list of changes - did anyone show evidence in this entire thread to the contrary?  Can you even argue that they won't be there?

How's about you answer the original question - why is changing the pressure vessel so much more significant than all those other changes?

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Offline beancounter

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Re: Speculation into what future versions of Dragon will involve
« Reply #142 on: 12/10/2012 06:24 am »
They didn't call it v1.1 or v1.5.  They called it 2.0, and I think this means that went back and designed it from scratch.

Sigh... In other words, you ignore what evidence is out there (CCiCap, statements by informed people like Jim) and decide to make stuff up. Well, prepare to be disappointed.

And BTW, since you seem to care so much about determining meaning in numerology - I believe Musk called in "Dragon 2", not "Dragon 2.0". There is a fine difference there, if you care to see it.

Seriously - the version # is the least important bit in that post... 

And what evidence are you talking about that I'm supposedly ignoring? That the pressure vessel hasn't changed?  I'd love to hear about any such evidence, one way or the other, since just like the rest of us here, I don't know....

But how about the rest of my list of changes - did anyone show evidence in this entire thread to the contrary?  Can you even argue that they won't be there?

How's about you answer the original question - why is changing the pressure vessel so much more significant than all those other changes?



I'll go with Option B above and prepare to be disappointed.  :)
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Offline cambrianera

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Re: Speculation into what future versions of Dragon will involve
« Reply #143 on: 12/10/2012 07:10 am »
A question to the people that believes that Dragon 2.0 will be similar to cargo Dragon: where is SpaceX going to fit SuperDracos?
Some models seen on displays or in artworks seems incompatible with dragon pressure vessel.

No, look closer, it is compatible. (both that display model and the rendering you attached are at least) Notice the raised areas around the thrusters. The SD's would be mounted on the outside of the pressure vessel, and the raised area/fairing would protect them during ascent.
If you are convinced, good.
Personally I see the attached model as some old jokes about big tv set disguised as flat tv, with the big hole in the wall and the next room half occupied by the tv set; in a house this is fun, in a pressure vessel...
Also, I cannot see the load path on the thin walls, anyway I hope "we'll be unveiling that fairly soon" (Elon's words).
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Offline Lars_J

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Re: Speculation into what future versions of Dragon will involve
« Reply #144 on: 12/10/2012 07:38 am »
They didn't call it v1.1 or v1.5.  They called it 2.0, and I think this means that went back and designed it from scratch.

Sigh... In other words, you ignore what evidence is out there (CCiCap, statements by informed people like Jim) and decide to make stuff up. Well, prepare to be disappointed.

And BTW, since you seem to care so much about determining meaning in numerology - I believe Musk called in "Dragon 2", not "Dragon 2.0". There is a fine difference there, if you care to see it.

Seriously - the version # is the least important bit in that post...

Yet it is your (apparently) entire basis for thinking that it is designed from scratch. 

Quote
And what evidence are you talking about that I'm supposedly ignoring? That the pressure vessel hasn't changed?  I'd love to hear about any such evidence, one way or the other, since just like the rest of us here, I don't know....

Who has claimed that the pressure vessel won't change at all? (It is demonstrably false, since the top of it will connect the docking collar instead of the berthing one) But you are making the claims about significant revisions. Back them up.

Quote
But how about the rest of my list of changes - did anyone show evidence in this entire thread to the contrary?  Can you even argue that they won't be there?

I think Dragon 2 will have wings without any evidence. Can you disprove it?  ::)
I think Dragon 2 will have a warp drive without any evidence. Can you disprove it? ::)

Offline A_M_Swallow

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Re: Speculation into what future versions of Dragon will involve
« Reply #145 on: 12/10/2012 07:44 am »
{snip}
I think Dragon 2 will have a warp drive without any evidence. Can you disprove it? ::)

Yes.  No warp drive has yet reached TRL 2.   :o  :P

Online meekGee

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Re: Speculation into what future versions of Dragon will involve
« Reply #146 on: 12/10/2012 02:06 pm »
Yet it is your (apparently) entire basis for thinking that it is designed from scratch. 
No, it is the list of changes I put up that made me call it "from scratch".

I'm still btw looking forward to any evidence to support your opinion. Me, I have none.  And, what wings?  I never said wings.

Tell me - which of these changes do you think *won't* happen:
(I don't think all of them will, just looking for your opinion)

- Super Dracos
- LAS control for SDs
- Landing control for SDs
- Structural changes to capsule to support SDs
- SDs that protrude outwards beyond what we've seen so far
- Larger propellant tanks
- Repositioning of thrusters on capsule wall, propellant line re-routing
- Landing gear anchored on periphery, not through heat shield as shown
- Docking mechanism
- Landing gear
- Outer mold line
- Aerodynamic flow during re-entry because of SDs
- Life support system
- Power system to support life support system
- Internal design for crew
- Shape of internal vessel

Then, tell me what you think will actually stay the same.

This way we won't have to argue about the semantics of "small" vs. "large" changes.

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Offline cambrianera

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Re: Speculation into what future versions of Dragon will involve
« Reply #147 on: 12/16/2012 01:11 pm »
Found another picture of "Naked Dragon".
Seriously, I can't see enough space to fit 8 SuperDracos, except for having very big external bulges, with lot of implications on airflow and load path.
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Offline joek

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Re: Speculation into what future versions of Dragon will involve
« Reply #148 on: 12/16/2012 10:27 pm »
In addition to the other references previously posted, you might want to look at this presentation, in particular slides 18, 19 and 29.
Quote from: SpaceX
- Both Dragon & Falcon 9 were designed from inception to readily accommodate crew
- Existing Dragon systems designed to accommodate escape system, including abort loads
- Thermal Control System & radiator are sized for crew requirements
- >210 days orbital life span: Positive energy balance...

There doesn't appear to be anything to suggest "from scratch"; everything SpaceX has said strongly suggests otherwise.

edit: In short, based on SpaceX's statements; from your list...
No substantive changes:
- Structural changes to capsule to support SDs
- Larger propellant tanks
- Power system to support life support system
- Shape of internal vessel
Expected/nominal changes:
- Docking mechanism
- Life support system (per SpaceX "up-rated... add CO2 & Humidity control")
- Internal design for crew (per SpaceX "Seats, displays and controls")
« Last Edit: 12/16/2012 10:52 pm by joek »

Offline beancounter

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Re: Speculation into what future versions of Dragon will involve
« Reply #149 on: 12/17/2012 12:59 am »
Found another picture of "Naked Dragon".
Seriously, I can't see enough space to fit 8 SuperDracos, except for having very big external bulges, with lot of implications on airflow and load path.


Yes I'd agree with the SD assessment unless there's a lot of extraneous equipment being used in the SD test version.  Looked a pictures of the Merlins.  Never seemed to be much difference between test and final engines though.
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Online meekGee

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Re: Speculation into what future versions of Dragon will involve
« Reply #150 on: 12/17/2012 02:51 am »
In addition to the other references previously posted, you might want to look at this presentation, in particular slides 18, 19 and 29.
Quote from: SpaceX
- Both Dragon & Falcon 9 were designed from inception to readily accommodate crew
- Existing Dragon systems designed to accommodate escape system, including abort loads
- Thermal Control System & radiator are sized for crew requirements
- >210 days orbital life span: Positive energy balance...

There doesn't appear to be anything to suggest "from scratch"; everything SpaceX has said strongly suggests otherwise.

edit: In short, based on SpaceX's statements; from your list...
No substantive changes:
- Structural changes to capsule to support SDs
- Larger propellant tanks
- Power system to support life support system
- Shape of internal vessel
Expected/nominal changes:
- Docking mechanism
- Life support system (per SpaceX "up-rated... add CO2 & Humidity control")
- Internal design for crew (per SpaceX "Seats, displays and controls")


Are you saying the current propellant tanks for the Dracos are already large enough for landing and LAS?

And that you can see where the SD's fit and attach?

I agree with you about the power system maybe being large enough already.

As always, my take about what SpaceX says is that it often reflects what's on the drawing boards, not what is currently flying. Case in point - engine out capability on F9, as articulated by Elon, matches what the Merlin 1D can do, but at the time he said it only the 1C existed as far as we knew.

Either way - most of the list still stands even if one or two of the bullets is already in the Dragon 1.0
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Offline Jason1701

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Re: Speculation into what future versions of Dragon will involve
« Reply #151 on: 12/17/2012 04:05 am »
In addition to the other references previously posted, you might want to look at this presentation, in particular slides 18, 19 and 29.
Quote from: SpaceX
- Both Dragon & Falcon 9 were designed from inception to readily accommodate crew
- Existing Dragon systems designed to accommodate escape system, including abort loads
- Thermal Control System & radiator are sized for crew requirements
- >210 days orbital life span: Positive energy balance...

There doesn't appear to be anything to suggest "from scratch"; everything SpaceX has said strongly suggests otherwise.

edit: In short, based on SpaceX's statements; from your list...
No substantive changes:
- Structural changes to capsule to support SDs
- Larger propellant tanks
- Power system to support life support system
- Shape of internal vessel
Expected/nominal changes:
- Docking mechanism
- Life support system (per SpaceX "up-rated... add CO2 & Humidity control")
- Internal design for crew (per SpaceX "Seats, displays and controls")


Are you saying the current propellant tanks for the Dracos are already large enough for landing and LAS?

And that you can see where the SD's fit and attach?

I agree with you about the power system maybe being large enough already.

As always, my take about what SpaceX says is that it often reflects what's on the drawing boards, not what is currently flying. Case in point - engine out capability on F9, as articulated by Elon, matches what the Merlin 1D can do, but at the time he said it only the 1C existed as far as we knew.

Either way - most of the list still stands even if one or two of the bullets is already in the Dragon 1.0

Dragon is thought to have about 500 m/s delta-v, which should be more than enough for either a launch abort or a thruster-assisted touchdown after a mission. A purely propulsive touchdown might be more than that can handle.

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Re: Speculation into what future versions of Dragon will involve
« Reply #152 on: 12/17/2012 04:41 am »
500 is not bad.  Didn't realize it was that much.
Is that including cosine errors when firing "downwards"?
Hopefully with the SD's sticking out, that effect will go away - cosine effects are forgiving over the first 15-20 degrees.

How much is used for de-orbiting?

500 is definitely enough for LAS (enough for 10g for 5 seconds, if anyone can take it)

For landing, in principle, you only need as much as your terminal velocity, which for a largely empty aluminum can will be (IIANM) some 100 m/s. Cynically speaking, the rest will only make it easier for S&R to find the capsule if the landing went badly. 

OK - so if the stored impulse is already 500 m/s, I'm taking the "larger fuel tanks" out of the list.

The structural attach points themselves are not a big deal either - they're a straight forward change, not the biggest item on that list.
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Offline cambrianera

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Re: Speculation into what future versions of Dragon will involve
« Reply #153 on: 12/17/2012 01:12 pm »
Looking at some old posts in "SpaceX:Advanced Launch Abort System(LAS)" I tried to get speculative dimensions of the SD.
Diameter about 200 mm (8"), lenght about 500 mm (20").
Pipes are about 40 mm (1 1/2").
See:
http://forum.nasaspaceflight.com/index.php?topic=24979.msg918360#msg918360
http://forum.nasaspaceflight.com/index.php?topic=24979.msg918361#msg918361
http://forum.nasaspaceflight.com/index.php?topic=24979.msg918470#msg918470
Not impossible, but quite tight to install.

Can't see where they fit into the displayed model's and artwork's bulges.
http://forum.nasaspaceflight.com/index.php?topic=30455.msg989774#msg989774
Considering also a pair of them has 130000 N of thrust, I can't see them attached to a thin, isogrid aluminium wall (of course, addictional load-bearing structures can be added).
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Offline joek

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Re: Speculation into what future versions of Dragon will involve
« Reply #154 on: 12/18/2012 02:53 am »
Dragon is thought to have about 500 m/s delta-v, which should be more than enough for either a launch abort or a thruster-assisted touchdown after a mission. A purely propulsive touchdown might be more than that can handle.

Another indication... Assuming SpaceX has done their homework and 120klb thrust from the Superdracos is sufficient for launch abort (whatever DragonRider's weight), then given 1230-1290kg propellant (current Dragon) and an isp of 250-270 sec (postulated), produces ~5.6-6.4sec burn at full thrust (assuming my math is correct).

Either way - most of the list still stands even if one or two of the bullets is already in the Dragon 1.0

We could go on all day making lists of the work to go from Dragon cargo to Dragon crew--as indicated by the cost and time required for CCiCap et. al.  Yes, there will be significant changes, especially those dictated by the LAS.  No one is disputing that.  However, that doesn't change the fact that by all indications SpaceX will maximize the use of Dragon cargo to get to Dragon crew, and that a "from scratch" effort for Dragon crew is not needed or desired.

Offline Magnus_Redin

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Re: Speculation into what future versions of Dragon will involve
« Reply #155 on: 12/18/2012 08:34 pm »
A merged upper stage and Dragon will only make sense once there is a significant flight history to prove that aborts at launch are only a statistical anomaly and can be ignored.

Otherwise you are back to creating a separating cabin and/or ejection seats, and you forfeit the advantage of a merged unit anyway.

Another idea would be to merge a reusable upper stage with the trunk for a low-margin reentry with the upper stage and high margin reentry with the manned part.

Offline cambrianera

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Re: Speculation into what future versions of Dragon will involve
« Reply #156 on: 12/20/2012 05:38 pm »
Tried to sketch an outline of Dragon with the estimated dimensions of SD.
Bigger than models we saw, but possible.
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Online meekGee

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Re: Speculation into what future versions of Dragon will involve
« Reply #157 on: 12/21/2012 05:54 am »
Seems reasonable as a "minimal change" outline.  Leaves room for the landing struts, too.
« Last Edit: 12/21/2012 05:54 am by meekGee »
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Offline solartear

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Re: Speculation into what future versions of Dragon will involve
« Reply #158 on: 12/21/2012 06:38 pm »
For landing, in principle, you only need as much as your terminal velocity, which for a largely empty aluminum can will be (IIANM) some 100 m/s. Cynically speaking, the rest will only make it easier for S&R to find the capsule if the landing went badly. 

OK - so if the stored impulse is already 500 m/s, I'm taking the "larger fuel tanks" out of the list.

How much extra margin will NASA require in case of extra wind, malfunctions, etc ?

Looks like they're planning to land it near populated areas, important launch facilities, jet flight paths, etc., and NASA wouldn't let SpaceX attempt to place that secondary payload with CRS1 into correct orbit because the oxygen only gave 95% instead of 99% chance of success. Granted the parachutes would make it less of a bullet, but they still don't want it suddenly dropping into middle of a city.

Offline Jim

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Re: Speculation into what future versions of Dragon will involve
« Reply #159 on: 12/21/2012 06:45 pm »

How much extra margin will NASA require in case of extra wind, malfunctions, etc ?

Looks like they're planning to land it near populated areas, important launch facilities, jet flight paths, etc., and NASA wouldn't let SpaceX attempt to place that secondary payload with CRS1 into correct orbit because the oxygen only gave 95% instead of 99% chance of success. Granted the parachutes would make it less of a bullet, but they still don't want it suddenly dropping into middle of a city.

Apples and oranges.  CRS 1 was going to the ISS, which is NASA's jurisdiction.  Landing area safety is the FAA's jurisdiction.
« Last Edit: 12/21/2012 06:46 pm by Jim »

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