totm nov 2023 SpaceX Discussion Thread

[Flying dutchman]

They could theoretically go fully expendable.. that thing can put something like 63 (metric?) Tons in to leo. Perhaps they can launch it all in one go and then bring the crew up with dragon.

 

But perhaps the fairing is a bit too small for that, idk..

[tater]

27 minutes ago, Flying dutchman said:

They could theoretically go fully expendable.. that thing can put something like 63 (metric?) Tons in to leo. Perhaps they can launch it all in one go and then bring the crew up with dragon.

 

But perhaps the fairing is a bit too small for that, idk..

Orion CSM is 26 tonnes, right? Any excess capacity on FH to LEO is stage 2 propellants. EM-1 is uncrewed anyway, no need for a Dragon.

FH to TLI is probably 18-22 tonnes, but as @sevenperforce said, perhaps the SM can do the extra burn itself.

Come to think of it, EM-1 is in fact not a nominal Orion mission anyway, there is no insertion for EM-1 any more. It’s just an elliptical Earth orbit. That change was a while ago. Seems like one launch to me, as elliptical as possible for FH, then an additional burn by Orion and done.

[tater]

Also:

(can you guys tell what time of day I’m sitting alone waiting for the family to come down to breakfast in London, lol).

[NSEP]

If SpaceX would launch Orion on Starship it would be the biggest joke in spaceflight history. Probably not going to happend.

[Green Baron]

2 hours ago, tater said:

(can you guys tell what time of day I’m sitting alone waiting for the family to come down to breakfast in London, lol).

Hey, you're in my timezone (but not in my weather ;-)).

Bienvenido !

[DDE]

3 hours ago, tater said:

Also:

(can you guys tell what time of day I’m sitting alone waiting for the family to come down to breakfast in London, lol).

I can see why a person like myself, jaded by default, would be skeptical of the comic book hero on the right.

[sevenperforce]

4 hours ago, tater said:

Orion CSM is 26 tonnes, right? Any excess capacity on FH to LEO is stage 2 propellants. EM-1 is uncrewed anyway, no need for a Dragon.

FH to TLI is probably 18-22 tonnes, but as @sevenperforce said, perhaps the SM can do the extra burn itself.

Come to think of it, EM-1 is in fact not a nominal Orion mission anyway, there is no insertion for EM-1 any more. It’s just an elliptical Earth orbit. That change was a while ago. Seems like one launch to me, as elliptical as possible for FH, then an additional burn by Orion and done.

EM-1 and EM-2 are both off-nominal Orion missions. No insertion; just a flyby. Falcon Heavy expendable can do 26.7 tonnes to GTO, which means it can do 26 tonnes about 70 m/s past GTO, leaving less than 400 m/s for the Orion SM. Orion's SM pushes over 2.6 km/s.

In fact, I suspect Falcon Heavy can expend the center core and recover the side cores downrange, if NASA is amenable to a longer SM burn.

[Barzon]

If someone has RSS, could they work out the max payload to GTO for a Falcon Heavy, with two extra boosters, and cross feed, with a air-started core stage?

[sh1pman]

Just now, Barzon Kerman said:

If someone has RSS, could they work out the max payload to GTO for a Falcon Heavy, with two extra boosters, and cross feed, with a air-started core stage?

Don't need RSS for that, a spreadsheet will suffice. I have such a spreadsheet, but I'm not at home yet.

[Barzon]

Ah, OK. I look forward to the results  

[NSEP]

4 hours ago, sevenperforce said:

EM-1 and EM-2 are both off-nominal Orion missions. No insertion; just a flyby. Falcon Heavy expendable can do 26.7 tonnes to GTO, which means it can do 26 tonnes about 70 m/s past GTO, leaving less than 400 m/s for the Orion SM. Orion's SM pushes over 2.6 km/s.

Doesn't the Orion SM only push the spacecraft 1.8km/s of Delta-V? The Apollo SM gives a 2.8km/s kick though. 

Anyways this wouldn't make much of a difference for the extra orbital kick.

[sevenperforce]

58 minutes ago, NSEP said:

Doesn't the Orion SM only push the spacecraft 1.8km/s of Delta-V? The Apollo SM gives a 2.8km/s kick though. 

Anyways this wouldn't make much of a difference for the extra orbital kick.

You're right; I was calculating the drop-in for LLO as if it was equivalent to a rendezvous with LOP-G when it is not. Getting from TLI into LLO (or back out) is 1.3 km/s; getting from TLI to LOP-G is only 430 m/s. From LOP-G back to Earth entry is 412 m/s because the transfers are asymmetric.

Pushing a 4-tonne ESPRIT module (EM-3 plan) from TLI to LOP-G with Orion's 316-second OMS-derived engine would cost 3.87 tonnes of propellant. The trip back, without ESPRIT, would burn an additional 2.74 tonnes of propellant. This checks out because it's less than the 9 tonnes of props on the currently-manifested Orion SM. If you burn the SM's tanks to empty while pushing only the CM, those nine tonnes of props should get you about 1.3 km/s, so I'm not sure why it's quoted as 1.8 km/s in sources.

But 1.3 km/s is plenty to push Orion beyond FH's highest orbit. In fact, the planned mission criteria for EM-2, even with SLS, was to use Orion's SM for a portion of the TLI burn:

Spoiler

One thing I'm still unsure of is whether EM-1 is a flyby or a distant retrograde orbit. If DRO remains the plan, then Orion needs every drop of props and cannot help with TLI. If it is just an uncrewed dry run of EM-2, then obviously it can.

Edited March 14, 2019 by sevenperforce

[sevenperforce]

According to this source, total dV for DRO insertion from LEO is less than 3.13 km/s. Since we know TLI is roughly 2.73 km/s, this means you need only about 400 m/s for capture into DRO as well as return.

So even if we go with the calculated 1.3 km/s on Orion rather than the quoted 1.8 km/s, that still gives us a 500 km/s reserve to complete TLI if FH can only push Orion+SM to GTO. TLI is 460 m/s past GTO, so there's EM-1 on FH, single-launch.

SLS is dead.

Edited March 14, 2019 by sevenperforce
500 km/s lol what is this a NSWR?

[sh1pman]

5 hours ago, sevenperforce said:

EM-1 and EM-2 are both off-nominal Orion missions. No insertion; just a flyby. Falcon Heavy expendable can do 26.7 tonnes to GTO, which means it can do 26 tonnes about 70 m/s past GTO, leaving less than 400 m/s for the Orion SM. Orion's SM pushes over 2.6 km/s.

In fact, I suspect Falcon Heavy can expend the center core and recover the side cores downrange, if NASA is amenable to a longer SM burn.

With no booster reuse, this monster can push almost 39 tons to GTO. With full reuse (2x RTLS, 2x ASDS booster landings) GTO payload drops to around 31 tons. Central core separates at around 5 km/s and burns up in all configurations.

Edited March 14, 2019 by sh1pman

[Bill Phil]

3 minutes ago, sevenperforce said:

According to this source, total dV for DRO insertion from LEO is less than 3.13 km/s. Since we know TLI is roughly 2.73 km/s, this means you need only about 400 m/s for capture into DRO as well as return.

So even if we go with the calculated 1.3 km/s on Orion rather than the quoted 1.8 km/s, that still gives us a 500 km/s reserve to complete TLI if FH can only push Orion+SM to GTO. TLI is 460 m/s past GTO, so there's EM-1 on FH, single-launch.

SLS is dead.

500 km/s? 

SLS was dead at the start. There was no intention from Congress to ever actually fly it.

[NSEP]

5 minutes ago, sevenperforce said:

According to this source, total dV for DRO insertion from LEO is less than 3.13 km/s. Since we know TLI is roughly 2.73 km/s, this means you need only about 400 m/s for capture into DRO as well as return.

So even if we go with the calculated 1.3 km/s on Orion rather than the quoted 1.8 km/s, that still gives us a 500 km/s reserve to complete TLI if FH can only push Orion+SM to GTO. TLI is 460 m/s past GTO, so there's EM-1 on FH, single-launch.

SLS is dead.

Hmmmm *Opens RSS/RO*

I think i did a Falcon Heavy/Orion in RSS/RO once, but i will have to redo it, maybe make a YouTube video.

[Barzon]

Please do! And a Falcon Super Heavy!

[sevenperforce]

18 minutes ago, sh1pman said:

With no booster reuse, this monster can push almost 39 tons to GTO. With full reuse (2x RTLS, 2x ASDS booster landings) GTO payload drops to around 31 tons. Central core separates at around 5 km/s and burns up in all configurations.

Where are you getting that? SpaceX advertises FH expendable at 26.7 tonnes to GTO; full reuse at 8 tonnes to GTO.

Ooooooooh you are talking about Falcon Super Heavy, aren't you?

16 minutes ago, Bill Phil said:

500 km/s? 

Hah!!

Quote

SLS was dead at the start. There was no intention from Congress to ever actually fly it.

Well yes.

Edited March 14, 2019 by sevenperforce

[sh1pman]

1 minute ago, sevenperforce said:

Where are you getting that? SpaceX advertises FH expendable at 26.7 tonnes to GTO; full reuse at 8 tonnes to GTO.

I'm calculating that in my spreadsheet. We're talking about Falcon Super Heavy with 4 boosters.

[Racescort666]

My first thought was, "why don't you stack a DCSS on top of a Falcon Heavy? The mass works out."

• Falcon Heavy Payload to LEO: 63 800 kg
• Orion Spacecraft (Including SM): 25 848 kg
• Delta Cryogenic Second Stage (wet): 30 710 kg
• FH mass margin: 7 242 kg
• LEO dV: 2972 m/s <- but this is the killer, not enough dV.

Plus, this would require an expendable FH.

[sh1pman]

1 minute ago, Racescort666 said:

My first thought was, "why don't you stack a DCSS on top of a Falcon Heavy? The mass works out."

• Falcon Heavy Payload to LEO: 63 800 kg
• Orion Spacecraft (Including SM): 25 848 kg
• Delta Cryogenic Second Stage (wet): 30 710 kg
• FH mass margin: 7 242 kg
• LEO dV: 2972 m/s <- but this is the killer, not enough dV.

Plus, this would require an expendable FH.

Discussed that in the SLS thread. Orion can use its own propulsion to finish the TLI injection. Problems: FH needs a custom payload adapter to integrate with DCSS, and 39A will need to be plumbed for hydrogen. 

[sevenperforce]

Just now, Racescort666 said:

My first thought was, "why don't you stack a DCSS on top of a Falcon Heavy? The mass works out."

• Falcon Heavy Payload to LEO: 63 800 kg
• Orion Spacecraft (Including SM): 25 848 kg
• Delta Cryogenic Second Stage (wet): 30 710 kg
• FH mass margin: 7 242 kg
• LEO dV: 2972 m/s <- but this is the killer, not enough dV.

Plus, this would require an expendable FH.

DCSS is unnecessary. FH can send Orion and its service module just past GTO, and Orion can complete the rest of a TLI at perigee with enough props left over for burns in and out of DRO.

Can do the same thing with EM-2 though it would either need to be man-rated or have the crew go up on a Dragon 2 on a Falcon 9, which means refitting 39A from F9 to FH while the crew wait in orbit.

Just now, sh1pman said:

Problems: FH needs a custom payload adapter to integrate with DCSS, and 39A will need to be plumbed for hydrogen. 

FH would need a custom payload adapter to integrate with Orion's SM anyway but no need for hydrogen.

[NSEP]

I tested the concept of using an Expendable Falcon Heavy and the Orion SM to boost it to do a lunar flyby in RO/RSS, and geuss what, it works!

You can see here the Delta-V of an expendable FH carrying an Orion spacecraft would be 12.8km/s while you need around 12.7km/s to reach TLI from the surface (9.5 is for orbit, 3.2 is for the TLI burn). I ended up with around 100m/s left in my fuel tanks to spend on correction burns, wich is more than enough. This is just speculation, its still sort of a crazy idea but i just couldn't resist.

Spoiler

Yes, it was a night launch (and splashdown). this mission was purely to test if it is going to work or not.

 

Transfer burn, first the Falcon Heavy/9 second stage gave it a 2-ish km/s kick and the SM later finished that kick,

 

We unfortunately didn't reach close enough to the Moon to take pretty pictures of craters up close, but we did enter its SOI

 

For those wondering, the solar panels kinda bugged out so i had to enable infinite power, i didn't cheat in extra fuel, again we had 12.8 km/s in total, 100m/s more than we had to. Sort of tight, but more than enough.

 

Spashdown, right in the middle in the ''Gulf of Aqaba''. Bullseye!? I didn't plan to land in such a small body of water.

 

 

[CatastrophicFailure]

1 hour ago, NSEP said:

tested the concept of using an Expendable Falcon Heavy and the Orion SM to boost it to do a lunar flyby in RO/RSS, and geuss what, it works!

... 

(I’m on an airplane and images aren’t loading right, but +1 anyway)

[tater]

EM-1 was originally DRO, but I think the requirement now (for any commercial flight) is just a flyby.

EM-2 has been a flyby for a while now.

so there is no LOI or TEI burn requirement at all.