### Author Topic: Mass of falcon 9 block 2  (Read 3680 times)

#### Seer

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##### Mass of falcon 9 block 2
« on: 03/17/2012 08:04 pm »
What will be the GLOW of the falcon 9 with the merlin D's and an extended propellent tank?

My guess is 450 tonnes, this is based on the need to lift 4.2 tonnes to gto for the Satmex satellites. Scaling from the present version of the falcon 9 gives the stated figure.

#### cuddihy

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##### Re: Mass of falcon 9 block 2
« Reply #1 on: 03/17/2012 10:03 pm »
Um, 145 klbf Merlin 1D sea-level thrust X 9 = 1.3 million lbf. minus a little bit to go up rather than staying stationary =~ 1.15 million lbm.

#### cuddihy

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##### Re: Mass of falcon 9 block 2
« Reply #2 on: 03/17/2012 10:05 pm »
Um, 145 klbf Merlin 1D sea-level thrust X 9 = 1.3 million lbf. minus a little bit to go up rather than staying stationary =~ 1.15 million lbm.
=521 metric tons

#### charliem

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##### Re: Mass of falcon 9 block 2
« Reply #3 on: 03/18/2012 01:10 pm »
Um, 145 klbf Merlin 1D sea-level thrust X 9 = 1.3 million lbf. minus a little bit to go up rather than staying stationary =~ 1.15 million lbm.

SpaceX has stated that they are designing to have multiple engine fail tolerance. So, I'd only take for granted the thrust of 7 engines.

That's 7 x 140.000 = 980.000 lbf, or 444.5 mt.

Moreover, if the acceleration is too low then gravity losses eat up a fair portion of your delta-v.

#### oldAtlas_Eguy

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##### Re: Mass of falcon 9 block 2
« Reply #4 on: 03/18/2012 01:44 pm »
Current propelant weight 325,185kg, propelant increase due to stretch ~114mt. Add in structual weight and engines of current at 8,009kg - engine weight of 4,615kg then increase the tank only weight by 1,189kg for a stretched dry weight of 9,190kg. That gives an ~new GLOW of 448mt.

#### edkyle99

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##### Re: Mass of falcon 9 block 2
« Reply #5 on: 03/18/2012 02:37 pm »
What will be the GLOW of the falcon 9 with the merlin D's and an extended propellent tank?

My guess is 450 tonnes, this is based on the need to lift 4.2 tonnes to gto for the Satmex satellites. Scaling from the present version of the falcon 9 gives the stated figure.

My guess has been 480 metric tonnes for awhile now, but I haven't revisited this question since last year.  This was, I believe, based on the performance data that SpaceX briefly posted, then removed, around the time of the Falcon Heavy announcement.  http://www.spacelaunchreport.com/falcon9.html

One way to guess would be to assume the same liftoff thrust to weight ratio as the Merlin 1C Falcon 9, which projects a GLOW of about 470 tonnes for the Merlin 1D version.

- Ed Kyle

#### ugordan

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##### Re: Mass of falcon 9 block 2
« Reply #6 on: 03/18/2012 02:39 pm »
This was, I believe, based on the performance data that SpaceX briefly posted, then removed, around the time of the Falcon Heavy announcement.

http://forum.nasaspaceflight.com/index.php?topic=24711.msg872742#msg872742

#### oldAtlas_Eguy

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##### Re: Mass of falcon 9 block 2
« Reply #7 on: 03/18/2012 03:06 pm »
This was, I believe, based on the performance data that SpaceX briefly posted, then removed, around the time of the Falcon Heavy announcement.

http://forum.nasaspaceflight.com/index.php?topic=24711.msg872742#msg872742

Allowing ~15mt for payload and payload structures (farring) [I forgot the payload when calculating the new GLOW] my 448mt value was off by ~15mt. To get to 480mt thats a 40% increase in propelant! Which is possible since some parts of the structure will not stretch causing the actual tank portions to stretch relatively more to make up the total length increase of 34%.

#### docmordrid

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##### Re: Mass of falcon 9 block 2
« Reply #8 on: 03/18/2012 03:24 pm »
What are the odds of them taking the core to 4 meters vs. a simple stretch? Seems their construction method would make diameter changes easier than usual.

Could they do it with the same thruat structure , or would M1D require a new one anyhow and give them the flexibility to go fore a bigger core at the same time?
DM

#### oldAtlas_Eguy

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##### Re: Mass of falcon 9 block 2
« Reply #9 on: 03/18/2012 03:27 pm »
The current F9 with M1C engines 95klbf has 3.6mt GTO (estimated) and 9.5mt (actual) LEO. With 40% more propelant and 40% more thrust that is almost a perfect scaling of payload capability giving 5mt GTO and 13.3 mt LEO. The 5mt GTO in the chart seems to have been correct but the 16mt LEO was not (16*3 = 48) but the FH crrosfeed accounts for more than a 10% performance increase of 20-30%. A 13.3 for non crrossfeed 40mt and a 30% increase due to crrossfeed results in 52mt. The only thing we know with certainty is that any values we use will be off that of actual, even SpaceX guesses (a much more acurate one than ours) until actual flight data tells them what the real performance is.

#### Jim

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##### Re: Mass of falcon 9 block 2
« Reply #10 on: 03/18/2012 04:24 pm »
What are the odds of them taking the core to 4 meters vs. a simple stretch? Seems their construction method would make diameter changes easier than usual.

it isn't construction that is the issue (and their method isn't any better at making diameter changes than others), it is infrastructure, tooling and GSE.

#### Seer

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##### Re: Mass of falcon 9 block 2
« Reply #11 on: 03/18/2012 05:09 pm »
The current F9 with M1C engines 95klbf has 3.6mt GTO (estimated) and 9.5mt (actual) LEO.

Is that standard gto orbit and with or without delta vee kit?

I assumed just 3 tonnes to gto with the current version.

#### oldAtlas_Eguy

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##### Re: Mass of falcon 9 block 2
« Reply #12 on: 03/18/2012 06:01 pm »
The current F9 with M1C engines 95klbf has 3.6mt GTO (estimated) and 9.5mt (actual) LEO.

Is that standard gto orbit and with or without delta vee kit?

I assumed just 3 tonnes to gto with the current version.

Not sure whether it is or isn't but I believe it is with delta-V kit. But by the time a GTO payload flies it will be on a F9 with M1D's so the estimated 3.6 GTO is a mute point. Since in reality it wont ever actually exist as an actual flight but be replaced with a F9 using M1D's non stretched with delta V kit having 4.45+mt GTO and a F9 stretched having 5+mt GTO.

#### oldAtlas_Eguy

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##### Re: Mass of falcon 9 block 2
« Reply #13 on: 03/18/2012 06:08 pm »
I think were getting off track talking about performance when this thread is about GLOW of the F9 Block II. I think it has been answered about as reasonably as can be with the value of 480mt supplied by SpaceX. In calculations that seems to be a reasonable value using info available on the F9 Block I (lengths, propelant weight, engine weights and total weight).

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