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

[Grandpa to Two]

Not sure where to post this; NASA has released a hi-res version of the Dragon 2 docking render from SpaceX.

I could wait for Saturday to confirm or not my thought that the IDA was designed with a drop down from the old docking port to the new docking port to make sure Dragon 2’s hat doesn’t contact the ISS?

[TrueBlueWitt]

Not sure where to post this; NASA has released a hi-res version of the Dragon 2 docking render from SpaceX.

I could wait for Saturday to confirm or not my thought that the IDA was designed with a drop down from the old docking port to the new docking port to make sure Dragon 2’s hat doesn’t contact the ISS?

The IDA is only the White part.. just a straight adapter to the Shuttle era  PMAs(black part with drop down)

[ncb1397]

Not sure where to post this; NASA has released a hi-res version of the Dragon 2 docking render from SpaceX.

I could wait for Saturday to confirm or not my thought that the IDA was designed with a drop down from the old docking port to the new docking port to make sure Dragon 2’s hat doesn’t contact the ISS?

More like Dragon was designed around IDA.

[kessdawg]

Possibly stupid question.  Do they have some sort of test on board to replace the astronauts expelling CO2?

[Grandpa to Two]

Not sure where to post this; NASA has released a hi-res version of the Dragon 2 docking render from SpaceX.

I could wait for Saturday to confirm or not my thought that the IDA was designed with a drop down from the old docking port to the new docking port to make sure Dragon 2’s hat doesn’t contact the ISS?

More like Dragon was designed around IDA.

I had thought the whole IDA/PMA were new but a look at the past via Wikipedia shows the PMA and Discovery. So it looks like the PMA was designed with the drop down so the shuttles could dock.

[DigitalMan]

Possibly stupid question.  Do they have some sort of test on board to replace the astronauts expelling CO2?

It should have a full ECLSS if it is identical to DM-2 as Hans has indicated.

[gongora]

Possibly stupid question.  Do they have some sort of test on board to replace the astronauts expelling CO2?

It should have a full ECLSS if it is identical to DM-2 as Hans has indicated.

I don't think they have anything to simulate the ECLSS usage of astronauts on DM-1 (and Hans doesn't always get every detail correct in the press conferences.)

[kessdawg]

Possibly stupid question.  Do they have some sort of test on board to replace the astronauts expelling CO2?

It should have a full ECLSS if it is identical to DM-2 as Hans has indicated.

I don't think they have anything to simulate the ECLSS usage of astronauts on DM-1 (and Hans doesn't always get every detail correct in the press conferences.)

Yeah that was more my question. Thanks.

[DigitalMan]

Possibly stupid question.  Do they have some sort of test on board to replace the astronauts expelling CO2?

It should have a full ECLSS if it is identical to DM-2 as Hans has indicated.

I don't think they have anything to simulate the ECLSS usage of astronauts on DM-1 (and Hans doesn't always get every detail correct in the press conferences.)

Yeah that was more my question. Thanks.

ah.  There ought to be some usage once it is inhabited while connected on station.  Hopefully this will be discussed during the webcasts that are planned.

[jcm]

I may have missed this upthread, but do we know if the DM-1 trunk is empty or does it have some unpressurized cargo aboard?

[nacnud]

I had thought the whole IDA/PMA were new but a look at the past via Wikipedia shows the PMA and Discovery. So it looks like the PMA was designed with the drop down so the shuttles could dock.

I think the PMA shape is more to do with accommodating the internal hatches and keeping the passageway as clear as possible. There is some discussion of it here: https://space.stackexchange.com/questions/19564/why-is-the-pressurized-mating-adapter-slanted

Interesting how past decisions can effect future designs.

[edkyle99]

From the press briefing (below).  I hope Stephen got his answer (drives me crazy that they don't share the numbers with the public).  The "Internet" suggests Crew Dragon may weigh 11-ish tonnes fueled without cargo, and up to 14+ tonnes with cargo.  Whatever the DM1 number, I expect this to be the heaviest-ever Falcon 9 payload.

"Stephen Clark, Spaceflight Now: Hi, Stephen Clark, Spaceflight Now, again. One question for maybe Hans or Kathy. Do you know about what the weight of the spacecraft is, in terms of pounds or kilograms at launch with all the fuel and cargo or crew loaded. About how heavy is it? And a little way ahead for the next week, you mentioned testing and analysis, what sort of milestones do you have over the next seven days to get ready for the launch? Fueling of the spacecraft with hypergolic fuel, et cetera.

Kathy Lueders, CCP: Well, the spacecraft, I'll have Stephanie get the specifics, she can get the specific weight, but the spacecraft's fueled right now. It's fueled, it's ready to go. It's over. And our folks have been following along with the fueling operation. We're moving towards obviously getting ready for Launch Readiness Review, which I think right now is the 27th. And we're rolling out to the pad on the 28th."

 - Ed Kyle

[abaddon]

From the press briefing (below).  I hope Stephen got his answer (drives me crazy that they don't share the numbers with the public).  The "Internet" suggests Crew Dragon may weigh 11-ish tonnes fueled without cargo, and up to 14+ tonnes with cargo.  Whatever the DM1 number, I expect this to be the heaviest-ever Falcon 9 payload.

Based on the analysis in this post, that should be within reasonable bounds of the F9R capability with an ASDS landing, with some margin.  Unclear what an RTLS landing would do to that and how much margin it would leave, seems to me it might be a little thin.

[Crispy]

Crewed Dragon will be flying a flatter ascent profile in order to provide safer abort conditions. This makes ASDS landing a certainty.

[Lars-J]

Crewed Dragon will be flying a flatter ascent profile in order to provide safer abort conditions. This makes ASDS landing a certainty.

A flatter ascent profile does not prevent RTLS, it just means that extra propellant has to be spent to get the stage back that way.

So it is not a certainty, it was even mentioned in the press conference that RTLS would be a possibility depending on future margin/performance. Extra margin has been reserved for this flight, margin which may be reduced/relaxed in the future.

[LouScheffer]

Crewed Dragon will be flying a flatter ascent profile in order to provide safer abort conditions. This makes ASDS landing a certainty.

A flatter ascent profile does not prevent RTLS, it just means that extra propellant has to be spent to get the stage back that way.

So it is not a certainty, it was even mentioned in the press conference that RTLS would be a possibility depending on future margin/performance. Extra margin has been reserved for this flight, margin which may be reduced/relaxed in the future.

The performance for RTLS is almost surely there.   For example, X-37 (RTLS) staged at 1629 m/s and Telstar 18 (ASDS), staged at 2271 m/s, a 642 m/s difference.  We know from the recent Nusantara launch that SpaceX can put 17.1t into parking orbit with ASDS recovery.  If they remove 642 m/s for RTLS, they can make this up provided the payload mass is no more than 13t.  When they did the pad abort test, the mass (from this article) was 11,115 kg, and I'd guess they'd use maximum mass for that test.  They will lose some for a higher inclination orbit and higher perigee, but they should be able to do quite a bit of trajectory flattening and still RTLS.

Similarly, NASA's LSP web site says Falcon 9 RTLS can put 10860 kg into a 51.6^o, 400 km circular orbit.  The current performance on GTO launches indicates performance about 6% better than the LSP numbers.  So they could RTLS with a Dragon-2 of the same mass as the launch abort test.

[CuddlyRocket]

I may have missed this upthread, but do we know if the DM-1 trunk is empty or does it have some unpressurized cargo aboard?

Nice question.  But I myself would think they would avoid putting anything in the trunk, at least for the first few missions, because the extra weight and that weight's location would probably affect the dynamics of an launch abort.

It probably would. Which means that if you want to validate the abort system's effectiveness in all envisaged circumstances, it should be at its maximum launch weight.

[abaddon]

It probably would. Which means that if you want to validate the abort system's effectiveness in all envisaged circumstances, it should be at its maximum launch weight.

No, for all envisioned circumstances an empty trunk might be quite a bit different from a full trunk and should also be included.  As should a trunk with a lot of heavy stuff mounted on one side.

Maybe we really need 10 in-flight abort tests, just to make absolutely sure.

Also this isn't the in-flight abort thread, so we should probably not continue posting continue discussion there.

[JimO]

Any word on the timing of the Stage-2 deorbit burn?

[envy887]

...

LAUNCH, LANDING AND DRAGON DEPLOYMENT
(all times are approximate)
  Hour/Min/Sec   Events
  +00:00:58   Max Q (moment of peak mechanical stress on the rocket)
  +00:02:33   1st stage main engine cutoff (MECO)
  +00:02:38   1st and 2nd stages separate
  +00:02:44   2nd stage engine starts
  +00:07:48   1st stage entry burn
  +00:08:57   2nd stage engine cutoff (SECO-1)
  +00:09:26   1st stage entry burn
  +00:09:37   1st stage landing
  +00:10:59   Crew Dragon separates from 2nd stage
  +00:12:00   Dragon nosecone open sequence begins

Why are there 2 first stage entry burns? From the listed times, the 2nd one should be the landing burn, although 11 seconds is a short landing burn. Usually those are 30 sec for a single engine landing.