SpaceX Falcon 9/Dragon CRS-2 SpX-2 MISSION GENERAL DISCUSSION

[oiorionsbelt]

Do those figures include the trunk payload?

I wonder about this too. CRS 2 has Trunk cargo, yes?

[Nomadd]

 Don't forget engine out capability. That's going to take away from payload if it's included. It's probably the reason SpaceX says to call them if you need more than 6800kg lifted. You'd have to give up engine out capability for most of the flight, which would raise the rates.

[Robotbeat]

Ballast, as Shuttle showed, has more to do with CG location and control stability (or not having to re-analyze stability after a manifest change) than "overperformance."

Yes, because Shuttle was a huge reentry vehicle. There's no guarantee whatsoever it'd be the same reason for ballasting the non-reentry-vehicle (yet!) Falcon 9.

[manboy]

Do those figures include the trunk payload?

I wonder about this too. CRS 2 has Trunk cargo, yes?

Two Heat Rejection Subsystem Grapple Fixtures (HRSGFs.)

[oiorionsbelt]

Do those figures include the trunk payload?

I wonder about this too. CRS 2 has Trunk cargo, yes?

Two Heat Rejection Subsystem Grapple Fixtures (HRSGFs.)

Thanks, do you know their mass and is it included in the 6000kg Dragon up mass for CRS SpX2 ?

[beancounter]

Do those figures include the trunk payload?

I wonder about this too. CRS 2 has Trunk cargo, yes?

Two Heat Rejection Subsystem Grapple Fixtures (HRSGFs.)

Hey that's great.  Forgot that this was on CRS 2.  We get to see further risk reduction and also new ISS moves unloading assuming they stream.  Can't see why they wouldn't.
Good luck SpaceX. 

[beancounter]

Also many thanks to everyone for correctly posting general comments and updates in the appropriate threads.  Means lots of saved time not having to wade through general stuff to get to the facts.
Cheers.

[joek]

E.g., you definitely forgot packaging, these "1200 lbs" are net cargo.
Here is quote from CRS-1 manifest:
Total Cargo Up Mass .......   882 pounds (400 kilograms)
Total Mass w/Packaging ... 1995 pounds (905 kilograms)

Do you have a source for those numbers? It appears those improperly mix up-mass and down-mass and packaging.  The CRS-1 Mission Press Kit shows far less packaging overhead:

Total Cargo Up Mass 882 pounds (400 kilograms)
Total Mass w/Packaging 1001 pounds (454 kilograms)
---
Total Down Mass 1673 pounds (759 kilograms)
Total Down Mass w/Packaging 1995 pounds (905 kilograms)

edit: Those are also reasonably consistent with the numbers from the COTS 2 Mission Press Kit:

Total Cargo [up] Mass 1,014 pounds (460 kilograms)
Total Mass Including Packaging 1,146 pounds (520 kilograms
---
Total Cargo [down] Mass 1,367 pounds (620 kilograms)
Total Mass Including Packaging 1,455 pounds (660 kilograms)

p.s. Those numbers exclude the weight of racks, ECLSS, power, etc.  Those likely add significant mass, but I haven't seen any credible numbers.

[Jim]

p.s. Those numbers exclude the weight of racks, ECLSS, power, etc.  Those likely add significant mass, but I haven't seen any credible numbers.

Those are part of the basic Dragon mass and not charged to the payload

[smoliarm]

E.g., you definitely forgot packaging, these "1200 lbs" are net cargo.
Here is quote from CRS-1 manifest:
Total Cargo Up Mass .......   882 pounds (400 kilograms)
Total Mass w/Packaging ... 1995 pounds (905 kilograms)

Do you have a source for those numbers? It appears those improperly mix up-mass and down-mass and packaging.  The CRS-1 Mission Press Kit shows far less packaging overhead:
...

It's funny, my source is THE SAME pdf, only I retrieved and saved it back then, in October 2012
Interesting, they have quite different numbers now, it is necessary to go through carefully.
I can not find any differences on the cover-page, like revision # or prep. date...

Lets see if I can attach my version of Press-Kit

(my system info this file: Saved on Saturday, ‎October ‎06, ‎2012)

[Antares]

Ballast, as Shuttle showed, has more to do with CG location and control stability (or not having to re-analyze stability after a manifest change) than "overperformance."

Yes, because Shuttle was a huge reentry vehicle. There's no guarantee whatsoever it'd be the same reason for ballasting the non-reentry-vehicle (yet!) Falcon 9.

Ascent stability is just as important, if not moreso, due to larger accelerations and more rapidly changing conditions.

What is the source for this claim of SpaceX ballast?  Is it known certainly that it is Falcon or Dragon or both?

[Robotbeat]

Ballast, as Shuttle showed, has more to do with CG location and control stability (or not having to re-analyze stability after a manifest change) than "overperformance."

Yes, because Shuttle was a huge reentry vehicle. There's no guarantee whatsoever it'd be the same reason for ballasting the non-reentry-vehicle (yet!) Falcon 9.

Ascent stability is just as important, if not moreso, due to larger accelerations and more rapidly changing conditions.
....

Sure, but the moment arm is much, much larger for a vehicle like Shuttle.

[ugordan]

What is the source for this claim of SpaceX ballast?  Is it known certainly that it is Falcon or Dragon or both?

IIRC it was at a press conference, I believe it was Suffredini who said that CRS-1 carried some ballast in addition to Orbcomm.

[Lars_J]

Ballast, as Shuttle showed, has more to do with CG location and control stability (or not having to re-analyze stability after a manifest change) than "overperformance."

Yes, because Shuttle was a huge reentry vehicle. There's no guarantee whatsoever it'd be the same reason for ballasting the non-reentry-vehicle (yet!) Falcon 9.

Ascent stability is just as important, if not moreso, due to larger accelerations and more rapidly changing conditions.

What is the source for this claim of SpaceX ballast?  Is it known certainly that it is Falcon or Dragon or both?

Here is the ballasting source, from NASA. It seems to imply that F9 was ballasted - See remarks starting at 44:15...
!

[joek]

p.s. Those numbers exclude the weight of racks, ECLSS, power, etc.  Those likely add significant mass, but I haven't seen any credible numbers.

Those are part of the basic Dragon mass and not charged to the payload

Right, specifically per CRS: "customer cargo" is without packaging; "cargo" is with packaging.  NASA pays for "cargo" exclusive of the racks, etc.  (In any case, if as previously someone suggests that lack of cargo indicates a shortfall in capability, the etc among other things needs to be considered.)

[Galactic Penguin SST]

What? 10 days to launch and still no advertisement for the XParty (TM)? 

And allow me to get a good laugh for this post from another thread:

Unavoidable of course, but it was obsolete before they installed the mural.

Now I want to hear from all of those people who claimed repeatedly that Ares I was too tall and skinny and would topple over, was unstable, etc..  I want them to explain to me how the Falcon 9 versions shown in the mural can possibly fly. 

 - Ed Kyle

[kevin-rf]

What? 10 days to launch and still no advertisement for the XParty (TM)? 

It's when you advertise early that the party get out of hand and the cops show up and call Jim on you

[hrissan]

Sure, but the moment arm is much, much larger for a vehicle like Shuttle.

As Merlin 1C Vac cannot throttle, the most likely reason for ballasting is excess acceleration at the end of the second stage burn, no?

Anybody knows how wide or narrow the safe range of Dragon center of gravity?

[Jason1701]

Sure, but the moment arm is much, much larger for a vehicle like Shuttle.

As Merlin 1C Vac cannot throttle, the most likely reason for ballasting is excess acceleration at the end of the second stage burn, no?

Anybody knows how wide or narrow the safe range of Dragon center of gravity?

M1CVac can throttle.

[Robotbeat]

I still agree that ballasting is probably being done to limit acceleration and such loads. Merlin 1C Vac can throttle, but its throttling range is limited (70-100%, I believe).