Starship specs - weight, volumes, etc

[equiserre]

Regarding payload volume: Elon just tweeted the max usable volume will be close to 1000 m3. If you take the spacex published Starship user manual, it has detailed dimensions of the payload fairing and the calculated volume is about 650m3. This space has an internal diameter of 8m max.
But even using 9m ID and using all space right to the top bulkhead, still dont get near 1000m3. Has somebody checked this?

Maybe he's already considering the flattened fwd bulkhead

Fael, are those volumes accurate? What internal diameter is implied? Those are consistent with Elon's tweet

[fael097]

Regarding payload volume: Elon just tweeted the max usable volume will be close to 1000 m3. If you take the spacex published Starship user manual, it has detailed dimensions of the payload fairing and the calculated volume is about 650m3. This space has an internal diameter of 8m max.
But even using 9m ID and using all space right to the top bulkhead, still dont get near 1000m3. Has somebody checked this?

Maybe he's already considering the flattened fwd bulkhead

Fael, are those volumes accurate? What internal diameter is implied? Those are consistent with Elon's tweet

Yeah it's a cad model, so that's the volume of those shapes when circular, assuming 9m of ID

[TheRadicalModerate]

Yeah it's a cad model, so that's the volume of those shapes when circular, assuming 9m of ID

Rafael, have you thought about adding an explicit "payload envelope" component to the model?  If you just make it stand off from the fairing by half a meter on all sides, you could get pretty accurate volumes.

[fael097]

Yeah it's a cad model, so that's the volume of those shapes when circular, assuming 9m of ID

Rafael, have you thought about adding an explicit "payload envelope" component to the model?  If you just make it stand off from the fairing by half a meter on all sides, you could get pretty accurate volumes.

I have, I calculated volume using the dimensions from the Starship User's Guide, must have posted in in a couple different threads back then

It's considerable smaller than 1000m³ so I don't think that's what Elon meant by usable space.

[TheRadicalModerate]

I have, I calculated volume using the dimensions from the Starship User's Guide, must have posted in in a couple different threads back then

It's considerable smaller than 1000m³ so I don't think that's what Elon meant by usable space.

Ah.  Missed that--sorry.

So let's assume that the stretched version is actually adding 4.76m of cylindrical height and that it's expendable, so you can get 18ish m³ of extra volume in the nose with no LOX header.  That would take us up to 944, which is getting pretty close.  From there, they'd only need to add an additional 1.1m of cylindrical height to the stretched version to hit 1000m³.

[docmordrid]

Yeah it's a cad model, so that's the volume of those shapes when circular, assuming 9m of ID

Rafael, have you thought about adding an explicit "payload envelope" component to the model?  If you just make it stand off from the fairing by half a meter on all sides, you could get pretty accurate volumes.

I have, I calculated volume using the dimensions from the Starship User's Guide, must have posted in in a couple different threads back then

It's considerable smaller than 1000m³ so I don't think that's what Elon meant by usable space.

Does this consider the two payload bay lengths from the User Guide? ISTM this indicates there will be a Starship with extra rings, and much more volume.

[fael097]

Yeah it's a cad model, so that's the volume of those shapes when circular, assuming 9m of ID

Rafael, have you thought about adding an explicit "payload envelope" component to the model?  If you just make it stand off from the fairing by half a meter on all sides, you could get pretty accurate volumes.

I have, I calculated volume using the dimensions from the Starship User's Guide, must have posted in in a couple different threads back then

It's considerable smaller than 1000m³ so I don't think that's what Elon meant by usable space.

Does this consider the two payload bay lengths from the User Guide? ISTM this indicates there will be a Starship with extra rings, and much more volume.

it doesn't, and that mention on the user's guide, that's absolutely no indication of a taller ship. could be an expendable ship without header and shorter main tanks, could be already considering flatter bulkheads, could be just wishful thinking, but definitely not a taller ship.

[TheRadicalModerate]

it doesn't, and that mention on the user's guide, that's absolutely no indication of a taller ship. could be an expendable ship without header and shorter main tanks, could be already considering flatter bulkheads, could be just wishful thinking, but definitely not a taller ship.

Why do you say "definitely not a taller ship"?  I agree that it could be any of the things you've mentioned here, but why rule out adding more rings to the payload bay?  ISTM that lengthening it would be roughly equivalent to the difference between a Cat A/B fairing and a Cat C fairing.

The thing on the bubble would be the difficulty in adapting the payload processing and launch infrastructure for the taller bay, but adding some extra height on whatever they do there doesn't sound very expensive if they plan ahead.

[docmordrid]

it doesn't, and that mention on the user's guide, that's absolutely no indication of a taller ship. could be an expendable ship without header and shorter main tanks, could be already considering flatter bulkheads, could be just wishful thinking, but definitely not a taller ship.

Why do you say "definitely not a taller ship"?  I agree that it could be any of the things you've mentioned here, but why rule out adding more rings to the payload bay?  ISTM that lengthening it would be roughly equivalent to the difference between a Cat A/B fairing and a Cat C fairing.

The thing on the bubble would be the difficulty in adapting the payload processing and launch infrastructure for the taller bay, but adding some extra height on whatever they do there doesn't sound very expensive if they plan ahead.

And I would add that payload integration into the payload module occurs on the ground in a (clearly large) clean room (per User Guide). It then gets craned up for integration  with the (already stacked?) propulsion module.

[TheRadicalModerate]

it doesn't, and that mention on the user's guide, that's absolutely no indication of a taller ship. could be an expendable ship without header and shorter main tanks, could be already considering flatter bulkheads, could be just wishful thinking, but definitely not a taller ship.

Why do you say "definitely not a taller ship"?  I agree that it could be any of the things you've mentioned here, but why rule out adding more rings to the payload bay?  ISTM that lengthening it would be roughly equivalent to the difference between a Cat A/B fairing and a Cat C fairing.

The thing on the bubble would be the difficulty in adapting the payload processing and launch infrastructure for the taller bay, but adding some extra height on whatever they do there doesn't sound very expensive if they plan ahead.

And I would add that payload integration into the payload module occurs on the ground in a (clearly large) clean room (per User Guide). It then gets craned up for integration  with the (already stacked?) propulsion module.

This has been a topic of some debate.  There's an awful lot of connections to be made in a non-cleanroom environment if you're hoisting noses onto the propulsion section:  LOX downcomer, high-pressure methox feeder lines for RCS, sensor/control buses for the canards, clean transitions for the TPS, and, last but hardly least, structural couplings that can handle EDL stresses.

I tried to make the argument you're making and got convinced that I was wrong.

[soyuzu]

With a new batch of Starships unwrapping itself, and the internal structure of Superheavy revealed, maybe it’s time for us to update the estimation of Starship-Superheavy system, especially on the mass of Flaps, cover and Superheavy barrel?

[equiserre]

With a new batch of Starships unwrapping itself, and the internal structure of Superheavy revealed, maybe it’s time for us to update the estimation of Starship-Superheavy system, especially on the mass of Flaps, cover and Superheavy barrel?

I keep an updated spreasheet with all the components as best we know, guesstimating what we don't, and still come up with 110t for starship and 210t for superheavy. So still some margin to get to early target weights of 120/230. Superheavy has the most uncertainty of course. Thrust structure is the biggest single unknown. I've allowed 12t for that.
I would love to see somebody else's estimations.

[soyuzu]

With a new batch of Starships unwrapping itself, and the internal structure of Superheavy revealed, maybe it’s time for us to update the estimation of Starship-Superheavy system, especially on the mass of Flaps, cover and Superheavy barrel?

I keep an updated spreasheet with all the components as best we know, guesstimating what we don't, and still come up with 110t for starship and 210t for superheavy. So still some margin to get to early target weights of 120/230. Superheavy has the most uncertainty of course. Thrust structure is the biggest single unknown. I've allowed 12t for that.
I would love to see somebody else's estimations.

Is it possible to provide a link to the spreadsheet, or upload it as attachments?

[equiserre]

With a new batch of Starships unwrapping itself, and the internal structure of Superheavy revealed, maybe it’s time for us to update the estimation of Starship-Superheavy system, especially on the mass of Flaps, cover and Superheavy barrel?

I keep an updated spreasheet with all the components as best we know, guesstimating what we don't, and still come up with 110t for starship and 210t for superheavy. So still some margin to get to early target weights of 120/230. Superheavy has the most uncertainty of course. Thrust structure is the biggest single unknown. I've allowed 12t for that.
I would love to see somebody else's estimations.

Is it possible to provide a link to the spreadsheet, or upload it as attachments?

Here. this spreadsheet estimates weight, position of center of mass and position of aerodynamic center of effort for AoA 90 deg only (very crudely estimated as area x Cd)

[wannamoonbase]

Thanks for the estimate, the weight estimates are encouraging.

Components I didn't see are the down comers for both vehicles

Also the SH grid fins and actuators.  The upper SH structure to distribute the forces from the grid fins will be beefier too.

Your estimates are encouraging, I say build heavy, use the margins and get flying successfully.

[equiserre]

Thanks for the estimate, the weight estimates are encouraging.

Components I didn't see are the down comers for both vehicles

Also the SH grid fins and actuators.  The upper SH structure to distribute the forces from the grid fins will be beefier too.

Your estimates are encouraging, I say build heavy, use the margins and get flying successfully.

pls check, both downcomers and gridfins have their own line. Structure/actuators for gridfins is bundled in "systems". As I get new data I keep debundling and including new separate items. The biggest unknown for Superheavy is the thrust structure. I allowed 12 t for it, but no idea how much it could weigh

[wannamoonbase]

Thanks for the estimate, the weight estimates are encouraging.

Components I didn't see are the down comers for both vehicles

Also the SH grid fins and actuators.  The upper SH structure to distribute the forces from the grid fins will be beefier too.

Your estimates are encouraging, I say build heavy, use the margins and get flying successfully.

pls check, both downcomers and gridfins have their own line. Structure/actuators for gridfins is bundled in "systems". As I get new data I keep debundling and including new separate items. The biggest unknown for Superheavy is the thrust structure. I allowed 12 t for it, but no idea how much it could weigh

Sorry, thanks for explaining.  I'll check again.

Yeah thrust structure, that is going to be interesting isn't it.  How does one get all that thrust into the side wall of the tanks, a  very interesting problem. 

Flying that huge cylinder back down and landing it will pretty straight forward for these guys, even if the vehicle is so darn big and hard to handle.

[spacenut]

Are you guys completely forgetting the three payload bays at the bottom of the Starship.  Add that to the total volume.  These can always be used to launch small sats during say a refueling mission.  Or any type of payload such as rovers, etc, that can be placed directly on the ground after landing on Mars. 

[steveleach]

Another thread has recently got onto the topic of the mass of Starship, so I thought it would be worth bumping this thread and also including another summary.  Most of the numbers are either taken from Fael's original post or are pure guesses.

If anyone has a better number for any of these elements I'd be more than happy to update them.

Item	Tons	Source
===	===	===
19 Rings	30.8	Fael
Engine ring	1.3	Fael
Nosecone	9.0	Fael
Bulkheads	9.9	Fael
Front flaps	5.0	Guess
Rear flaps	10.0	Guess
Header tanks	1.3	Fael
Downcomer	1.0	Guess
Thrust puck	2.0	Guess
3 x SL Raptors	4.5	Fael
Batteries	0.6	beels
Flap actuators	1.0	Guess
RCS	0.5	Guess
Legs	1.0	Guess
Stringers	1.0	Guess
Hatches	1.0	Guess
Wiring	0.5	Guess
Avionics	0.5	Guess
COPVs	3.0	Guess
Lifting points	1.0	Guess
---	---	---
SN10	80.3	Total
---	---	---
3 x Vac Raptors	6.3	Fael
TPS tiles	10.0	Fael
Chomper	5.0	Guess
Payload mount	5.0	Guess
Solar panels	5.0	Guess
Radiators	5.0	Guess
Full legs	6.0	Guess (extra)
Full RCS	2.0	Guess (extra)
---	---	---
Cargo Starship	124.6	Total

[Aeneas]

Another thread has recently got onto the topic of the mass of Starship, so I thought it would be worth bumping this thread and also including another summary.  Most of the numbers are either taken from Fael's original post or are pure guesses.

If anyone has a better number for any of these elements I'd be more than happy to update them.

Item	Tons	Source
===	===	===
19 Rings	30.8	Fael
Engine ring	1.3	Fael
Nosecone	9.0	Fael
Bulkheads	9.9	Fael
Front flaps	5.0	Guess
Rear flaps	10.0	Guess
Header tanks	1.3	Fael
Downcomer	1.0	Guess
Thrust puck	2.0	Guess
3 x SL Raptors	4.5	Fael
Batteries	0.6	beels
Flap actuators	1.0	Guess
RCS	0.5	Guess
Legs	1.0	Guess
Stringers	1.0	Guess
Hatches	1.0	Guess
Wiring	0.5	Guess
Avionics	0.5	Guess
COPVs	3.0	Guess
Lifting points	1.0	Guess
---	---	---
SN10	80.3	Total
---	---	---
3 x Vac Raptors	6.3	Fael
TPS tiles	10.0	Fael
Chomper	5.0	Guess
Payload mount	5.0	Guess
Solar panels	5.0	Guess
Radiators	5.0	Guess
Full legs	6.0	Guess (extra)
Full RCS	2.0	Guess (extra)
---	---	---
Cargo Starship	124.6	Total

THANK YOU! I was looking for this thread quite a bit! I wanted to validate my model. And one of my big questions is, still, the actual flap mass. How comfortable are you with your guess of 10 and 5 for aft and front flaps?