totm nov 2023 SpaceX Discussion Thread

[CatastrophicFailure]

4 hours ago, sh1pman said:

Hyperloop is not just a high speed tunnel. It’s a high speed vacuum tunnel. Which is insane for several reasons, not the least of which is safety.

They seem to have backed away from the vacuum thing in the short term, tho it can be argued, if they’re going to launch passengers into vacuum, zooming them through one doesn’t sound that far fetched. Hyperloop can still be faster and more efficient than boats over a few km even without the vacuum. 

[mikegarrison]

1 hour ago, CatastrophicFailure said:

They seem to have backed away from the vacuum thing in the short term, tho it can be argued, if they’re going to launch passengers into vacuum, zooming them through one doesn’t sound that far fetched. Hyperloop can still be faster and more efficient than boats over a few km even without the vacuum. 

I thought the idea was partial vacuum, to reduce drag but still have lift via ground effect.

(For the record, I thought, and still think, "hyperloop" is going nowhere.)

Edited June 17, 2020 by mikegarrison

[Nightside]

1 hour ago, mikegarrison said:

I thought the idea was partial vacuum, to reduce drag but still have lift via ground effect.

(For the record, I thought, and still think, "hyperloop" is going nowhere.)

Just vacuum out the top of the tube with an air hockey floor.

[kerbiloid]

A starship-wide launch hyperloop to stratosphere.

[RealKerbal3x]

Unless I'm mistaken, it looks like they've patched up the hole in SN7. Maybe they'll try for a true test to destruction and see how much it can really handle.

 

[kerbiloid]

A quick patch for SN7.

Now it's SN 7.1.

[tater]

Riiight.

You (literally anyone) first!

 

[Xd the great]

1 hour ago, tater said:

Riiight.

You (literally anyone) first!

 

Won't be surprised if Elon personally rides the first flight.

[kerbiloid]

He has rejected the idea of his Martian flight as too dangerous, probably he won't ride the water tank and this time.

[tater]

 

[Nightside]

14 hours ago, kerbiloid said:

A quick patch for SN7.

Now it's SN 7.1.

Always wait for the bugfix version before boarding.

[mikegarrison]

11 hours ago, tater said:

Riiight.

You (literally anyone) first!

 

Isn't any suborbital flight "Earth-to-Earth"? (In fact, almost all orbital flights too, in a sense....)

[cubinator]

Just now, mikegarrison said:

Isn't any suborbital flight "Earth-to-Earth"? (In fact, almost all orbital flights too, in a sense....)

I suppose it's a little different if you're starting in one spot and stopping in a different one...they've been doing this with Falcon 9 boosters for years now.

[tater]

39 minutes ago, mikegarrison said:

Isn't any suborbital flight "Earth-to-Earth"? (In fact, almost all orbital flights too, in a sense....)

I think the Viv person is not a native English speaker and was referring to "Point to Point" travel.

[mikegarrison]

38 minutes ago, cubinator said:

I suppose it's a little different if you're starting in one spot and stopping in a different one.

Like, say, starting on shore and ending on a barge in the ocean?

[cubinator]

Just now, mikegarrison said:

Like, say, starting on shore and ending on a barge in the ocean?

Yeah, exactly. Totally unproven ground.

[tater]

Yeah, but she means with passengers. It's a discussion about Starship use as an "airliner." (not something I expect to see any time soon)

[Nightside]

2 hours ago, tater said:

Yeah, but she means with passengers. It's a discussion about Starship use as an "airliner." (not something I expect to see any time soon)

I’d be much happier riding a rocket-plane with wings.

[RealKerbal3x]

 

[RCgothic]

Wow, this'll help make Starlink more economical to launch!

 

[wumpus]

9 hours ago, Nightside said:

I’d be much happier riding a rocket-plane with wings.

Depends on the rocket-plane.  Shuttle didn't have a great record.  X-15 did slightly better (similar number of missions and only one loss of life/crew and vehicle), but the sample sizes are too small to be significant.  It might well be easier to improve retropropulsive landing than increase the safety of a spaceplane.

[sevenperforce]

29 minutes ago, wumpus said:

9 hours ago, Nightside said:

I’d be much happier riding a rocket-plane with wings.

Depends on the rocket-plane.  Shuttle didn't have a great record.  X-15 did slightly better (similar number of missions and only one loss of life/crew and vehicle), but the sample sizes are too small to be significant.  It might well be easier to improve retropropulsive landing than increase the safety of a spaceplane.

I'd be much happier riding a passively-stable capsule. Although chutes are a harder problem than KSP would lead us to believe.

When it comes to passive aerodynamic stability, a broad truncated cone (Apollo CM, Orion) is more stable than a narrow truncated cone (Crew Dragon), which is more stable than a blunted hemisphere (Soyuz), which is more stable than a blended lifting body (X-37), which is more stable than a spaceplane (Orbiter), which is more stable than whatever Starship is.

SpaceX has demonstrated that they can do retropropulsive landing, so I am not worried about that. I am worried about passive stability from re-entry interface until landing burn ignition. Just look at CRS-16. The booster had enough passive aerodynamic stability to survive entry and to maintain roughly consistent pointing up to landing burn ignition, and the engine burn successfully dropped it into the drink intact (although its subsequent, unavoidable tipover was not pretty). But Starship does not have enough passive stability to do this. A stuck hinge could mean Starship goes nose-down, tail-first, or tailspins...all of which are unrecoverable.

[Codraroll]

6 minutes ago, sevenperforce said:

Although chutes are a harder problem than KSP would lead us to believe.

Not so sure about that. In real life, somebody will probably tap you on the shoulder and give you a reminder if you design a parachute-dependent landing capsule without a parachute.

[sevenperforce]

Just now, Codraroll said:

Not so sure about that. In real life, somebody will probably tap you on the shoulder and give you a reminder if you design a parachute-dependent landing capsule without a parachute.

True, but the chutes in KSP never foul, never tangle, and never have trouble opening.

[tater]

28 minutes ago, sevenperforce said:

SpaceX has demonstrated that they can do retropropulsive landing, so I am not worried about that. I am worried about passive stability from re-entry interface until landing burn ignition. Just look at CRS-16. The booster had enough passive aerodynamic stability to survive entry and to maintain roughly consistent pointing up to landing burn ignition, and the engine burn successfully dropped it into the drink intact (although its subsequent, unavoidable tipover was not pretty). But Starship does not have enough passive stability to do this. A stuck hinge could mean Starship goes nose-down, tail-first, or tailspins...all of which are unrecoverable.

Yeah, this.

Cargo makes sense to me. Crew vehicle in space? Sure, why not. EDL on Mars? OK, that's gonna be risky regardless. Earth with crew? Yikes. Long pole.

I still think that it has enough margin for a LES in any Earth-Moon use case, or even NASA style Mars exploration (for liftoff or EDL at Earth). Simply put there is no reason for more than some smallish number of passengers (10?). "Wasting" a decent % of payload mass on a LES is not a big deal when you can take 150t to LEO. Seems like they could make a 10-20 ton crew capsule on top, including LES motors and chutes that could hold as many people as they would need for space use short of their colonization goal.