SpaceX Falcon 9 / Dragon 2 : SpX-DM1 : March 2, 2019 : DISCUSSION

[Grandpa to Two]

How does Dragon compare in size, weight and meters cubed to Dragon 2?

So very interesting, I appreciate your giving the comparisons side by side. Until now my impressions were the capsules were of the same size, at least the basic pressurized bell would be the same. It looks like the Dragon 2 is in fact different, although very close to Dragon.

[CorvusCorax]

How does Dragon compare in size, weight and meters cubed to Dragon 2?

So very interesting, I appreciate your giving the comparisons side by side. Until now my impressions were the capsules were of the same size, at least the basic pressurized bell would be the same. It looks like the Dragon 2 is in fact different, although very close to Dragon.

Both vehicles have very similar payload capacity and internal volume. But Dragon2 also hosts an internal launch abort system, inc engines, larger tanks, a docking system and much more capable life support.

That results in larger dimensions and higher dry mass for the same payload and slightly reduced volume.
They basically added a lot of things

[woods170]

How does Dragon compare in size, weight and meters cubed to Dragon 2?

So very interesting, I appreciate your giving the comparisons side by side. Until now my impressions were the capsules were of the same size, at least the basic pressurized bell would be the same. It looks like the Dragon 2 is in fact different, although very close to Dragon.

Both vehicles have very similar payload capacity and internal volume. But Dragon2 also hosts an internal launch abort system, inc engines, larger tanks, a docking system and much more capable life support.

That results in larger dimensions and higher dry mass for the same payload and slightly reduced volume.
They basically added a lot of things

The basic part of each Dragon (be it cargo or crew versions) is the pressure vessel (known at SpaceX as "the weldment).
The pressure vessel for Crew Dragon is very similar to that of cargo Dragon, but having a deeper "bucket" section. This increases overall height of the Crew Dragon, compared to cargo Dragon.
Diameter at the heathshield is identical between crew- and cargo Dragon. Both ships also have similar bell-shaped OMLs.

[Nomadd]

 Is that right? Dry mass is 9525kg compared to 4200kg for Dragon 1?

[woods170]

Is that right? Dry mass is 9525kg compared to 4200kg for Dragon 1?

No, it is not correct.
The dry mass number for cargo Dragon is correct.

The number for Crew Dragon is not. This is because that number is publically sourced from the pad abort test where that number - of 9525 kg - was for the entire pad abort stack. Which included not only the pad abort test vehicle, but also mass sims for crew, a dummy, as well as a steel truss structure and a simulated upper part of F9.
The actual dry mass of Crew Dragon is - as far as I know - not publically known at this time.

[scr00chy]

The actual dry mass of Crew Dragon is - as far as I know - not publically known at this time.

This official document says:

Dragon-2 weighs approximately 16,976 pounds without cargo.

[MATTBLAK]

How much of that mass component is the Trunk?

[eeergo]

So what're these three pins on the nosecone? They look to have been exposed during reentry and not protected by some detachable cover. Maybe some interface for the CAA (they're right over the hatch)?

EDIT: Actually, reviewing orbital photos I noticed the recess is uncovered but there don't appear to be pins? So some kind of data or commanding interface for recovery ops?

[craiglv2]

Except for many photos on the boat and dock, we never saw any updates on the crew dragon's condition (except for photos), the status of downloaded cargo, or the transport for processing for next flight--the inflight abort test. Does anyone have any updates on these?

[woods170]

The actual dry mass of Crew Dragon is - as far as I know - not publically known at this time.

This official document says:

Dragon-2 weighs approximately 16,976 pounds without cargo.

If that's the dry weight, and the wording of that document suggest it is, it would put the dry weight of Crew Dragon at 7700 kg, which would make it 1.8 metric tons lighter than the number Nomadd provided earlier. This lower number is much more realistic I think.

[Nomadd]

How much of that mass component is the Trunk?

And how much is fuel?

[Alexphysics]

The actual dry mass of Crew Dragon is - as far as I know - not publically known at this time.

This official document says:

Dragon-2 weighs approximately 16,976 pounds without cargo.

If that's the dry weight, and the wording of that document suggest it is, it would put the dry weight of Crew Dragon at 7700 kg, which would make it 1.8 metric tons lighter than the number Nomadd provided earlier. This lower number is much more realistic I think.

I think it's most probable that the mass on that document is the mass of the empty capsule, the mass Nomadd said is most probably that mass plus the mass of th trunk (1.8 metric tons sounds about right for the trunk, I don't see it having a mass higher than 2 metric tons). We also know that Crew Dragon is above 12 metric tons at launch, which would mean all the fuel mass would be in the order of 2-3 metric tons, that to me sounds right too.

[daedalus1]

The actual dry mass of Crew Dragon is - as far as I know - not publically known at this time.

This official document says:

Dragon-2 weighs approximately 16,976 pounds without cargo.

If that's the dry weight, and the wording of that document suggest it is, it would put the dry weight of Crew Dragon at 7700 kg, which would make it 1.8 metric tons lighter than the number Nomadd provided earlier. This lower number is much more realistic I think.

I think it's most probable that the mass on that document is the mass of the empty capsule, the mass Nomadd said is most probably that mass plus the mass of th trunk (1.8 metric tons sounds about right for the trunk, I don't see it having a mass higher than 2 metric tons). We also know that Crew Dragon is above 12 metric tons at launch, which would mean all the fuel mass would be in the order of 2-3 metric tons, that to me sounds right too.

Just a note.
If you spell ton as tonne, you don't need to prefix 'metric'.

[gongora]

Just a note.
If you spell ton as tonne, you don't need to prefix 'metric'.

If we spelled ton as tonne we'd be british.

[daedalus1]

Just a note.
If you spell ton as tonne, you don't need to prefix 'metric'.

If we spelled ton as tonne we'd be british.

No mate. It's a universal spelling for a metric ton. If anything it's origin is French.

[eriblo]

Just a note.
If you spell ton as tonne, you don't need to prefix 'metric'.

If we spelled ton as tonne we'd be british.

No mate. It's a universal spelling for a metric ton. If anything it's origin is French.

Since most of the numbers we have in this case are either in kg or in pounds it might be best to avoid using ton or tonne (t) instead, despite those being conveniently sized for rocket stuff - this discussion is a regular occurrence 

I personally find someone clarifying "metric ton" funny as the ton as used in the USA is metric, defined as exactly 907.18474 kg  And please stay away from the milliteslas!

[Robotbeat]

The actual dry mass of Crew Dragon is - as far as I know - not publically known at this time.

This official document says:

Dragon-2 weighs approximately 16,976 pounds without cargo.

If that's the dry weight, and the wording of that document suggest it is, it would put the dry weight of Crew Dragon at 7700 kg, which would make it 1.8 metric tons lighter than the number Nomadd provided earlier. This lower number is much more realistic I think.

I think it's most probable that the mass on that document is the mass of the empty capsule, the mass Nomadd said is most probably that mass plus the mass of th trunk (1.8 metric tons sounds about right for the trunk, I don't see it having a mass higher than 2 metric tons). We also know that Crew Dragon is above 12 metric tons at launch, which would mean all the fuel mass would be in the order of 2-3 metric tons, that to me sounds right too.

Just to put this in perspective...

If the mass without cargo is 9500kg and the mass of the propellant is 2.5 tons, and the Isp of the Dracos is 300s, that means it can do about 680m/s delta-v. That's enough (plenty) to enter and exit EML-2 (technically only requires 432m/s to do that, so we can afford to speed it up a bit).

Anyway.

[scr00chy]

And how much is fuel?

From the same FAA document I linked above:

The Dragon-2 could contain up to 4,885 pounds of propellant which includes 3,004 pounds of NTO and 1,881 pounds of MMH.

[Comga]

And how much is fuel?

From the same FAA document I linked above:

The Dragon-2 could contain up to 4,885 pounds of propellant which includes 3,004 pounds of NTO and 1,881 pounds of MMH.

That’s 2,216 kg prop =1,363 kg NTO +853 kg MMH

[strawwalker]

And how much is fuel?

From the same FAA document I linked above:

The Dragon-2 could contain up to 4,885 pounds of propellant which includes 3,004 pounds of NTO and 1,881 pounds of MMH.

That is on reentry after having used up what was needed for the mission. From the IFA draft assessment Dragon's propellant amounts are listed as ~2600 kg. Around 1500 kg of that is earmarked for launch escape and the other nearly 1100 kg presumably for maneuvers, attitude control, and deorbit.

Dragon would contain approximately 5,650 pounds of hypergolic propellant, including approximately 3,500 pounds of dinitrogen tetroxide (NTO) and 2,150 pounds of monomethylhydrazine (MMH). Dragon would contain approximately 2,400 pounds of residual propellant after the abort test.

That's a difference of less than 350 kg, not really enough to cut it for a round trip to ISS, but maybe those Reentry Environmental Assessment prop numbers are maximums meant to cover some failed rendezvous scenario where Dragon is reentering from a lower orbit?