SpaceX Falcon 1 Mass Budget

I'm trying to guesstimate the mass budget for a
Falcon 1. Public information seems to be limited
at the moment, especially since SpaceX has
removed its Falcon 1 payload users guide from its
web site. I'm wondering if anyone has the information
on-hand.

But I did download a copy of the guide last year.
From it, from information still on the SpaceX web
site, and from old news clippings, I have found the
following information.

Vehicle total mass: 27.2 tonnes
Stage 1 Sea Level Thrust: 34.92 tonnes
Stage 1 Vacuum Thrust: 41.72 tonnes
Stage 2 Vacuum Thrust: 3.175 tonnes
Acceleration at Stage 1 Burnout: 6.5 g
Acceleration at Stage 2 Ignition: 0.65 g
Acceleration at Stage 2 Burnout: 4.5 g
Payload to 200 km x 28.5 deg LEO: 0.57 tonnes
Claimed Stage 1 Mass Fraction Goal: 94%
Claimed Stage 2 Mass Fraction Goal: 91%

Payoad fairing separation occurs after Stage 2
ignition. The acceleration data was provided
without specifying the assumed payload mass,
and the payload fairing mass is unknown.

So I have a problem with too many unknowns
to provide absolute answers. If I guess
0.35 tonnes for both the payload fairing and the
modeled payload used to provide the acceleration
numbers, I get the following results.

Stage 1 Mass at Liftoff: 22.315 tonnes
Stage 1 Mass at Burnout: 1.533 tonnes
Stage 2 Mass at Ignition: 3.965 tonnes
Stage 2 Mass at Burnout: 0.357 tonnes
Payload Fairing Mass: 0.35 tonnes

This provides a 93% Stage 1 mass fraction and
a 91% Stage 2 mass fraction. The Stage 1
fraction seems believable because SpaceX
ended up with a heavier Merlin than originally
planned, according to updates on the SpaceX
web site.

But there is a great deal of uncertainty in these
numbers. A different payload mass assumption
would drive second stage mass above 4 tonnes,
for example. Does anyone have better numbers?

- Ed Kyle

Ed Kyle wrote:
I'm trying to guesstimate the mass budget for a
Falcon 1. Public information seems to be limited
at the moment, especially since SpaceX has
removed its Falcon 1 payload users guide from its
web site. I'm wondering if anyone has the information
on-hand.

But I did download a copy of the guide last year.
From it, from information still on the SpaceX web
site, and from old news clippings, I have found the
following information.

Vehicle total mass: 27.2 tonnes
Stage 1 Sea Level Thrust: 34.92 tonnes
Stage 1 Vacuum Thrust: 41.72 tonnes
Stage 2 Vacuum Thrust: 3.175 tonnes
Acceleration at Stage 1 Burnout: 6.5 g
Acceleration at Stage 2 Ignition: 0.65 g
Acceleration at Stage 2 Burnout: 4.5 g
Payload to 200 km x 28.5 deg LEO: 0.57 tonnes
Claimed Stage 1 Mass Fraction Goal: 94%
Claimed Stage 2 Mass Fraction Goal: 91%

Payoad fairing separation occurs after Stage 2
ignition. The acceleration data was provided
without specifying the assumed payload mass,
and the payload fairing mass is unknown.

So I have a problem with too many unknowns
to provide absolute answers. If I guess
0.35 tonnes for both the payload fairing and the
modeled payload used to provide the acceleration
numbers, I get the following results.

Stage 1 Mass at Liftoff: 22.315 tonnes
Stage 1 Mass at Burnout: 1.533 tonnes
Stage 2 Mass at Ignition: 3.965 tonnes
Stage 2 Mass at Burnout: 0.357 tonnes
Payload Fairing Mass: 0.35 tonnes

This provides a 93% Stage 1 mass fraction and
a 91% Stage 2 mass fraction. The Stage 1
fraction seems believable because SpaceX
ended up with a heavier Merlin than originally
planned, according to updates on the SpaceX
web site.

But there is a great deal of uncertainty in these
numbers. A different payload mass assumption
would drive second stage mass above 4 tonnes,
for example. Does anyone have better numbers?

- Ed Kyle

I just noticed an interesting omission--although all the falcon 1 pics
on SpaceX's website show the fuel line from the lower stage tank (I
assume it's kersosene on top), none of the Falcon 5 or Falcon 9 pics
have that 'detail'. The fuel (or LOX?) either magically gets down to
the engines or runs internally. hmm. I wonder if it's because that
decision actually hasn't been made yet or if it means anything at all?

Also, the fact that Musk put such a small LOX generator on Omelek makes
me wonder if he's actually much more hesitent to put up the money for
Falcon 9 than he was for Falcon 1. Maybe he got burned so far?

Tom

In sci.space.tech Tom Cuddihy wrote:
Also, the fact that Musk put such a small LOX generator on Omelek
makes me wonder if he's actually much more hesitent to put up the
money for Falcon 9 than he was for Falcon 1. Maybe he got burned so
far?

Or he doesn't plan on all that many launches from Omelek?

rick jones
--
firebug n, the idiot who tosses a lit cigarette out his car window
these opinions are mine, all mine; HP might not want them anyway...
feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH...

Also, the fact that Musk put such a small LOX generator on Omelek makes
me wonder if he's actually much more hesitent to put up the money for
Falcon 9 than he was for Falcon 1. Maybe he got burned so far?

The "small" LOX plant at Omelek is supposed to make about one ton per day.
That seems to be a pretty big LOX plant. That would support more than one falcon 1 a month.
It makes no sense to put in a larger plant, until there is a larger need.

Paul

Rick Jones wrote:
In sci.space.tech Tom Cuddihy wrote:
Also, the fact that Musk put such a small LOX generator on Omelek
makes me wonder if he's actually much more hesitent to put up the
money for Falcon 9 than he was for Falcon 1. Maybe he got burned so
far?

Or he doesn't plan on all that many launches from Omelek?

rick jones
--
firebug n, the idiot who tosses a lit cigarette out his car window
these opinions are mine, all mine; HP might not want them anyway...
feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH...

The first one's supposed to launch from there.

In article ,
Rick Jones wrote:

In sci.space.tech Tom Cuddihy wrote:
Also, the fact that Musk put such a small LOX generator on Omelek
makes me wonder if he's actually much more hesitent to put up the
money for Falcon 9 than he was for Falcon 1. Maybe he got burned so
far?

Or he doesn't plan on all that many launches from Omelek?

Exactly. Commercial operations there would be a pain the ass.