Skylon

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27 minutes ago, Ultimate Steve said:

So cancelling the rotation wouldn't lead to a loss of translation because of the angles of off-axis thrusters? Can you explain that better to me? That doesn't seem like it should work in my head, but I may be wrong. 

Yeah, it should work. Let me throw together a diagram.

translation-with-FUS.png

Far left shows D2 still attached to FUS. Center shows a nominal port thruster firing. While free-flying, this would go through the CoM, but with the FUS attached it will induce rotation around the much lower CoM, producing yaw to starboard. To counter that, D2 would need to also fire a port-aft and a starboard-fore thruster; this will induce a yaw to port within the capsule, counteracting the rotation around the stack CoM.

6 minutes ago, RCgothic said:

Also Orion has full mobility. All Dragon needs to do is hold orientation, which is easy, even connected to a FUS.

If that was the case then FH wouldn't even need to launch dragon; it could simply launch an empty FUS and it could use its cold-gas thrusters to hold orientation.

However, Orion's autonomous docking software is not yet operational, so it would need to passively hold orientation while Dragon performed the actual approach and soft docking.

Dragon 2's software is fully operational. It is capable of carrying externally-manifested payloads (up to at least 3.5 tonnes and potentially as much as 6 tonnes) in the trunk, which means it is already capable of compensating for a lower or higher center of mass. Enabling it to mate with FUS attached could actually be as simple as updating the CoM variable to allow a much lower CoM.

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12 hours ago, Xd the great said:

Yah know, sounds like those roclets i build in the first days of ksp. A rocket with 11 stages.

I wasn’t joking about two Block Ds. Throwing together multiple upper stages is what Roscosmos - who already use effectively four-stage vehicles - seem to consider the way forward. Yenisei and Don have something like five-six stages/sep events in total.

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7 hours ago, sevenperforce said:

Here's what could actually work, right now, with no modifications to anything other than software:

  1. Repeat EFT-1, leaving Orion and its fully-fueled ESM in an elliptical earth orbit.
  2. Launch a reused Dragon 2 on FHB5e into the same elliptical earth orbit; do not separate Dragon 2 from FHUS.
  3. Use Dragon 2's autonomous docking capabilities to mate Orion and Dragon 2. Software updates required for Dragon 2 to compensate for the added mass and altered CoM with the FHUS still attached.
  4. Use residuals in FHUS to push Crew Dragon + Orion + ESM into TLI.
  5. Orion and Crew Dragon separate after TLI. FHUS is ejected into heliocentric orbit; Crew Dragon completes a mid-course correction and performs a free-return; Orion performs DRO or NRHO injection for EM-1.
  6. Crew Dragon tests heat shield on entry from cislunar space.
  7. Orion performs cislunar mission, then burns EOI for completion.

No new vehicles, no new adapters, nothing. FH has same US configuration as in the Tesla test flight (modifications for extended restart).

Decided to try and validate this with some cold, hard numbers. 

The DCSS on EFT-1 put Orion into a funky suborbital trajectory with a high apogee but a perigee below the surface. If it has reached the same apogee from a standard 200 km reference orbit, it would have been 1088 m/s past LEO. I'll lower it to 950 km/s past LEO to accommodate that.

Dragon 2 masses 10.9 tonnes with props and no cargo or crew. We know FHB5e can deliver 26,700 kg to GTO, meaning it can definitely deliver Dragon 2 to GTO plus 15.8 tonnes of residuals. Estimating FHUS at 4.5 tonnes, this means it departs its 200-km parking orbit with 45.3 tonnes of residuals. Matching the same orbit as EFT-1 (assuming this is 950 m/s past LEO) would leave it with 29.9 tonnes of residuals. There's some additional conservatism here.

Dragon 2 will burn off a fair amount of its own props in the rendezvous and docking with Orion, but I'll pretend it doesn't, for conservatism. At docking, the stack masses 10.9 tonnes for Dragon 2, 4.5 tonnes for FHUS dry mass, 29.9 tonnes of residuals, and 25.8 tonnes for Orion+ESM, for a total of 71.1 tonnes in eccentric orbit.

The FHUS's 29.9 tonnes of residuals will push the stack an additional 1860 m/s for a total of 2,810 m/s past LEO. TLI is 2,730 m/s past LEO. So the Falcon Heavy, launched to the same eccentric earth orbit as EFT-1, can push both Dragon 2 and Orion+ESM to TLI with 80 m/s of dV to spare.

The math checks out.

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Seems like they could aim for a ballistic capture into a distant lunar orbit, then the entire SM is available for getting back. The particular orbit seems of little importance, the thermal issues, etc shouldn't change.

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14 minutes ago, sevenperforce said:

Decided to try and validate this with some cold, hard numbers. 

The DCSS on EFT-1 put Orion into a funky suborbital trajectory with a high apogee but a perigee below the surface. If it has reached the same apogee from a standard 200 km reference orbit, it would have been 1088 m/s past LEO. I'll lower it to 950 km/s past LEO to accommodate that.

Dragon 2 masses 10.9 tonnes with props and no cargo or crew. We know FHB5e can deliver 26,700 kg to GTO, meaning it can definitely deliver Dragon 2 to GTO plus 15.8 tonnes of residuals. Estimating FHUS at 4.5 tonnes, this means it departs its 200-km parking orbit with 45.3 tonnes of residuals. Matching the same orbit as EFT-1 (assuming this is 950 m/s past LEO) would leave it with 29.9 tonnes of residuals. There's some additional conservatism here.

Dragon 2 will burn off a fair amount of its own props in the rendezvous and docking with Orion, but I'll pretend it doesn't, for conservatism. At docking, the stack masses 10.9 tonnes for Dragon 2, 4.5 tonnes for FHUS dry mass, 29.9 tonnes of residuals, and 25.8 tonnes for Orion+ESM, for a total of 71.1 tonnes in eccentric orbit.

The FHUS's 29.9 tonnes of residuals will push the stack an additional 1860 m/s for a total of 2,810 m/s past LEO. TLI is 2,730 m/s past LEO. So the Falcon Heavy, launched to the same eccentric earth orbit as EFT-1, can push both Dragon 2 and Orion+ESM to TLI with 80 m/s of dV to spare.

The math checks out.

EFT-1 didn't have a service module, though, so the Orion on this flight would be way heavier.

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1 hour ago, Ultimate Steve said:

EFT-1 didn't have a service module, though, so the Orion on this flight would be way heavier.

EFT-1 had a boilerplate ESM. Same mass, but very little dV.

1 hour ago, tater said:

Seems like they could aim for a ballistic capture into a distant lunar orbit, then the entire SM is available for getting back. The particular orbit seems of little importance, the thermal issues, etc shouldn't change.

Easily. Even if they had to burn a little of the ESM to complete the TLI (which I am pretty confident they wouldn't need to do), it would still work.

8 minutes ago, CatastrophicFailure said:

Rumor has it... the doors are opening....

giphy.gif

Pod bay doors?

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Probs the integration bay doors, ready to roll out the Falcon Heavy.

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Posted (edited)
giphy.gif
Edited by sh1pman

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1 hour ago, MaverickSawyer said:

Probs the integration bay doors, ready to roll out the Falcon Heavy.

Nevermind, it appears the Falcon Heavy has been upstaged... :o

... at least for tonight...

20 minutes ago, sh1pman said:
giphy.gif
 

Son of a gun... he stole my line. :huh:

But also...

 

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17 minutes ago, StrandedonEarth said:

It blew out the flare?

Steam from the engine went in front of it, I think.

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W

 

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2 minutes ago, tater said:

W

 

**presses F to pay respects**

1 hour ago, CatastrophicFailure said:

But also...

 

We gon' rock this club
We gon' go all night
We gon' light it up
Like it's dynamite

Ignition over a naked pad has such a lovely futuristic blast pattern.

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3 minutes ago, sevenperforce said:

Raptor is officially a flight-tested engine.

Welcome to the future.

Does it really count as a flight? It was secured pretty tightly to the launch pad, it may have gone up a few inches but wasn't really intended to be a full flight.

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Posted (edited)
24 minutes ago, sevenperforce said:

Raptor is officially a flight-tested engine.

Welcome to the future.

The future already started here \/ \/ \/

Image result for crs 8 landing gif

3 years ago as of next Monday.

Edited by cubinator

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4 hours ago, sevenperforce said:

Dragon 2 will burn off a fair amount of its own props in the rendezvous and docking with Orion, but I'll pretend it doesn't, for conservatism. At docking, the stack masses 10.9 tonnes for Dragon 2, 4.5 tonnes for FHUS dry mass, 29.9 tonnes of residuals, and 25.8 tonnes for Orion+ESM, for a total of 71.1 tonnes in eccentric orbit.

The FHUS's 29.9 tonnes of residuals will push the stack an additional 1860 m/s for a total of 2,810 m/s past LEO. TLI is 2,730 m/s past LEO. So the Falcon Heavy, launched to the same eccentric earth orbit as EFT-1, can push both Dragon 2 and Orion+ESM to TLI with 80 m/s of dV to spare.

I like it! And they didn't mention having considered it yet. But would just the docking clamps be enough to keep it all steady during the TLI burn? My quick numbers show the end of the TLI burn would be at ~.9G (39% throttle, 934kN thrust, 41.2t ) . I've heard the new docking clamps are snazzy, but I don't know much about them.

(Oh also, could you put Doyouwonda's name on the quote in this post?)

 

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8 minutes ago, Ultimate Steve said:

Does it really count as a flight? It was secured pretty tightly to the launch pad, it may have gone up a few inches but wasn't really intended to be a full flight.

It moved under its own power.

It counts.

2 minutes ago, Cunjo Carl said:

I like it! And they didn't mention having considered it yet. But would just the docking clamps be enough to keep it all steady during the TLI burn? My quick numbers show the end of the TLI burn would be at ~.9G (39% throttle, 934kN thrust, 41.2t ) . I've heard the new docking clamps are snazzy, but I don't know much about them.

They can handle it. Same docking system intended for Constellation.

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Posted (edited)

Sweet baby raptor jesus.

This thing is going to be all kinds of awesome.

Edited by RedKraken

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17 minutes ago, sevenperforce said:

It moved under its own power.

It counts.

Give it a few weeks ;)

 

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48 minutes ago, Cunjo Carl said:

 My quick numbers show the end of the TLI burn would be at ~.9G (39% throttle, 934kN thrust, 41.2t ) .

I doubt if they would run it at such low thrust, given how hard it is to throttle a ffsc engine.

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Posted (edited)
9 minutes ago, Xd the great said:

I doubt if they would run it at such low thrust, given how hard it is to throttle a ffsc engine.

Ah, different conversation. This was for the Merlin 1D vac on the Falcon Heavy Upper Stage for an idea sevenperforce put forward.

 

@sevenperforce You know, you might actually send the suggestion along to them. The look on the administrator's face was one of someone desperately trying to build as many fallback plans as possible, so sending it their way couldn't hurt. The worst they'll do is ignore it, and it's possible they didn't think of the elliptical orbit rendezvous, which is rather the crux of the thing.

public-inquiries@hq.nasa.gov  or maybe https://www.nasa.gov/content/submit-a-question-for-nasa

Edited by Cunjo Carl

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STARHOPPER LIVES!

I do still kinda miss the nosecone, but it’s a bit unnecessary I guess.

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