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Dragon - Why only 1001 pounds of cargo going up?



 
 
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  #1  
Old October 8th 12, 03:38 PM posted to sci.space.station
Alejandro Zuzek[_2_]
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Posts: 5
Default Dragon - Why only 1001 pounds of cargo going up?

According to Spaceflight Now, the first operational cargo flight of the Dragon spacecraft is carrying 1001 pounds of cargo. On the other hand, on the same site it is mentioned that Dragon is capable of carrying 3310 kg. I assume that figure is for ISS flights since the Dragon data sheet on the SpaceX site says it can carry 6000 kg into LEO and up to 3000 kg down mass. So why only 1001 pounds of cargo on this flight and why only 1995 pounds of down mass? To this layman, it seems that the flight is underutilized.

References:
http://spaceflightnow.com/falcon9/00...hmanifest.html
http://spaceflightnow.com/falcon9/00...nmanifest.html
http://www.spacex.com/downloads/dragonlab-datasheet.pdf
  #3  
Old October 8th 12, 05:13 PM posted to sci.space.station
Brian Thorn[_2_]
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Posts: 2,266
Default Dragon - Why only 1001 pounds of cargo going up?

On Mon, 8 Oct 2012 07:38:35 -0700 (PDT), Alejandro Zuzek
wrote:

According to Spaceflight Now, the first operational cargo flight of the Dragon spacecraft is carrying 1001 pounds of cargo. On the other hand, on the same site it is mentioned that Dragon is capable of carrying 3310 kg. I assume that figure is for ISS flights since the Dragon data sheet on the SpaceX site says it can carry 6000 kg into LEO and up to 3000 kg down mass. So why only 1001 pounds of cargo on this flight and why only 1995 pounds of down mass? To this layman, it seems that the flight is underutilized.


Part of the reason is that the full Dragon capability has to wait for
Falcon 9 v1.1 whicih debuts next year.

But stiil, this is very lightly loaded.

Brian
  #4  
Old October 8th 12, 07:38 PM posted to sci.space.station
Jeff Findley[_2_]
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Default Dragon - Why only 1001 pounds of cargo going up?

In article , bthorn64
@suddenlink.net says...

On Mon, 8 Oct 2012 07:38:35 -0700 (PDT), Alejandro Zuzek
wrote:

According to Spaceflight Now, the first operational cargo flight of the Dragon spacecraft is carrying 1001 pounds of cargo. On the other hand, on the same site it is mentioned that Dragon is capable of carrying 3310 kg. I assume that figure is for ISS flights since the Dragon data sheet on the SpaceX site says it can carry 6000 kg into LEO and up to 3000 kg down mass. So why only 1001 pounds of cargo on this flight and why only 1995 pounds of down mass? To this layman,

it seems that the flight is underutilized.

Part of the reason is that the full Dragon capability has to wait for
Falcon 9 v1.1 whicih debuts next year.

But stiil, this is very lightly loaded.


Considering the same launch carried Orbcomm?s O2G-1 communications
satellite (313 lb), I'd say it's lightly loaded.

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer
  #5  
Old October 9th 12, 02:15 PM posted to sci.space.station
Jeff Findley[_2_]
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Posts: 1,388
Default Dragon - Why only 1001 pounds of cargo going up?

In article ,
says...

In article , bthorn64
@suddenlink.net says...

On Mon, 8 Oct 2012 07:38:35 -0700 (PDT), Alejandro Zuzek
wrote:

According to Spaceflight Now, the first operational cargo flight of the Dragon spacecraft is carrying 1001 pounds of cargo. On the other hand, on the same site it is mentioned that Dragon is capable of carrying 3310 kg. I assume that figure is for ISS flights since the Dragon data sheet on the SpaceX site says it can carry 6000 kg into LEO and up to 3000 kg down mass. So why only 1001 pounds of cargo on this flight and why only 1995 pounds of down mass? To this

layman,
it seems that the flight is underutilized.

Part of the reason is that the full Dragon capability has to wait for
Falcon 9 v1.1 whicih debuts next year.

But stiil, this is very lightly loaded.


Considering the same launch carried Orbcomm?s O2G-1 communications
satellite (313 lb), I'd say it's lightly loaded.


One thing that only the "space media" seem to be reporting is that the
Falcon 9 first stage suffered an engine failure. At least in this case,
the redundancy in the design worked and Dragon made it into orbit
without the "mainstream media" noticing.

On the CNN website, they said:

Mission control called it "a picture-perfect launch and a
flawless flight of Falcon."

I wouldn't call it "picture-perfect" if an engine failed on the way up,
but I certainly would call it successful.

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer
  #6  
Old October 9th 12, 02:59 PM posted to sci.space.station
Jeff Findley[_2_]
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Posts: 1,388
Default Dragon - Why only 1001 pounds of cargo going up?

In article om,
says...

On 12-10-08 14:38, Jeff Findley wrote:

Considering the same launch carried Orbcomm?s O2G-1 communications
satellite (313 lb), I'd say it's lightly loaded.



Is it possible that when you combine Progress, ATV, HTV and now Dragon,
there is more uplift capacity than needed ?


I would think that the ISS partners will find uses for the "excess"
capacity, so it won't truly be "excess" in the long run.

BTW, one of the NASA officials had mentioned that with the last shuttle
flights, they brought a huge amount of equipment for experiments that
are scheduled over a long period of time so if the station hasn't
finished with those experiments yet, there won't be much room/time to
bring new ones.


Dragon will be extremely useful for its ability to return experimental
results and equipment to earth. No other spacecraft currently in use
for ISS cargo resupply has that ability.

Another possibility is that because Dragon is new, it isn't yet part

of
the critical path so much of the planning scheduled the "real" cargo
between ATV/Progress/HTV.


It would be prudent to use it, at least initially, to deliver cargo
which could be easily replaced should the mission fail. I would expect
this level of caution to extend to Orbital's Cygnus resupply vessel as
well.

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer
  #7  
Old October 9th 12, 10:48 PM posted to sci.space.station
snidely
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Posts: 1,303
Default Dragon - Why only 1001 pounds of cargo going up?

JF Mezei wrote on 10/9/2012 :

http://www.spacex.com/press.php?page=20121008 says:
##
Approximately one minute and 19 seconds into last night's launch,


[jfm continues:]
Would be interesting to know at what point (in seconds) after launch,
they can afford to lose an engine. Wouldn't engines still be needed at
100% thrust at that point in time ?


At 1m19s? Not necessarily. If you read the rest of the SpaceX
posting,
you'll see that they routinely shut down 2 engines earlier than the
others -- one of those "let's tailor the acceleration profile to not
smash anything or anyone on board" adjustments.

At what time they normally do that, and how much they throttle the
engines at what time, I'm not sure, but 1m19s is on the order of the
time the Shuttle would throttle for MaxQ.

I assume that they remained at 100% longer then planned in order to
achieve the delta-V that the first stage is supposed to give ?


Again, not necessarily. The total burn was longer than normal, but how
that affected the throttle settings may be more complex than you
assume.

/dps

--
Who, me? And what lacuna?


  #8  
Old October 10th 12, 03:43 AM posted to sci.space.station
Brian Thorn[_2_]
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Posts: 2,266
Default Dragon - Why only 1001 pounds of cargo going up?

On Mon, 08 Oct 2012 17:27:49 -0400, JF Mezei
wrote:

On 12-10-08 14:38, Jeff Findley wrote:

Considering the same launch carried Orbcomm?s O2G-1 communications
satellite (313 lb), I'd say it's lightly loaded.



Is it possible that when you combine Progress, ATV, HTV and now Dragon,
there is more uplift capacity than needed ?


No, they're barely breaking even in comparison to Shuttle.
Shuttle was intended to make four flights to the Station each year,
each flight delivering about 15,000 lbs, or 60,000 lbs. per year.

Dragon's payload is to be 7,000 lbs. once fully operational, Cygnus is
to be 6,000 lbs. so we're looking at something like five flights of
each per year to replace Shuttle.

Progress, ATV and HTV were to be flying anyway, so they are not
Shuttle replacements.

Brian
  #9  
Old October 11th 12, 10:18 AM posted to sci.space.station
Brian Gaff
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Posts: 2,312
Default Dragon - Why only 1001 pounds of cargo going up?

Maybe the answer is in the last press release. It says this mission has the
capability to return frozen samples. Could it be that the equipment for
keeping temperatures low is rather heavy?

Brian

--
From the Sofa of Brian Gaff Reply address is active
"Snidely" wrote in message
news:mn.4b787dcad7d7d03f.127094@snitoo...
JF Mezei wrote on 10/9/2012 :

http://www.spacex.com/press.php?page=20121008 says:
##
Approximately one minute and 19 seconds into last night's launch,


[jfm continues:]
Would be interesting to know at what point (in seconds) after launch,
they can afford to lose an engine. Wouldn't engines still be needed at
100% thrust at that point in time ?


At 1m19s? Not necessarily. If you read the rest of the SpaceX posting,
you'll see that they routinely shut down 2 engines earlier than the
others -- one of those "let's tailor the acceleration profile to not smash
anything or anyone on board" adjustments.

At what time they normally do that, and how much they throttle the engines
at what time, I'm not sure, but 1m19s is on the order of the time the
Shuttle would throttle for MaxQ.

I assume that they remained at 100% longer then planned in order to
achieve the delta-V that the first stage is supposed to give ?


Again, not necessarily. The total burn was longer than normal, but how
that affected the throttle settings may be more complex than you assume.

/dps

--
Who, me? And what lacuna?




  #10  
Old October 11th 12, 10:24 AM posted to sci.space.station
Brian Gaff
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Posts: 2,312
Default Dragon - Why only 1001 pounds of cargo going up?

Well, its a clever system. I guess it was only shut down as a precaution.
could easily have been a sensor issue. If the craft had been near its limit
in weight though, could this still have been achieved.

Brian

--
From the Sofa of Brian Gaff Reply address is active
"JF Mezei" wrote in message
eb.com...
On 12-10-09 09:15, Jeff Findley wrote:

One thing that only the "space media" seem to be reporting is that the
Falcon 9 first stage suffered an engine failure. At least in this case,
the redundancy in the design worked and Dragon made it into orbit
without the "mainstream media" noticing.


http://www.spacex.com/press.php?page=20121008 says:
##
Approximately one minute and 19 seconds into last night's launch, the
Falcon 9 rocket detected an anomaly on one first stage engine. Initial
data suggests that one of the rocket's nine Merlin engines, Engine 1,
lost pressure suddenly and an engine shutdown command was issued. We
know the engine did not explode, because we continued to receive data
from it. Panels designed to relieve pressure within the engine bay were
ejected to protect the stage and other engines. Our review of flight
data indicates that neither the rocket stage nor any of the other eight
engines were negatively affected by this event.

As designed, the flight computer then recomputed a new ascent profile in
real time to ensure Dragon's entry into orbit for subsequent rendezvous
and berthing with the ISS. This was achieved, and there was no effect on
Dragon or the cargo resupply mission.
##

Would be interesting to know at what point (in seconds) after launch,
they can afford to lose an engine. Wouldn't engines still be needed at
100% thrust at that point in time ?

I assume that they remained at 100% longer then planned in order to
achieve the delta-V that the first stage is supposed to give ?







 




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