Jump to content

SpaceX Discussion Thread


Skylon

Recommended Posts

39 minutes ago, Xd the great said:

It needs airliner-like safety. is it a god idea to give it so much instability?

Again, "instability" refers to stability when flying like a plane. It is not flying, it is falling at terminal velocity. The f;laps aren't supposed to generate any lift. If this was a airplane,that would be bad. This is not an airplane. The most "unstable" configuration is the most stable for these purposes.

 

11 minutes ago, Raven Industries said:

I think the airline comparison breaks down more often than we'd like. Space travel is inherently more dangerous than air travel, and vehicles meant for the space environment may need to break a few rules that airlines hold to. 

I'm gonna have to agree on this, I don't think they'll ever get quite *that* good (safer than other vehicles, maybe,  but not airliner-safe). However, SpaceX certainly doens't think this, or else they wouldn't be talking about P2P.

 

Just now, Xd the great said:

Personally, I think starship needs to be able to survive a malfunctioning winglet.

Aircraft can't always survive a malfunctioning engine.

Link to comment
Share on other sites

16 minutes ago, ThatGuyWithALongUsername said:

Again, "instability" refers to stability when flying like a plane. It is not flying, it is falling at terminal velocity. The f;laps aren't supposed to generate any lift. If this was a airplane,that would be bad. This is not an airplane. The most "unstable" configuration is the most stable for these purposes.

So, can it fall in a "stable" manner? That is what I am worried about.

Link to comment
Share on other sites

2 minutes ago, Xd the great said:

Personally, I think starship needs to be able to survive a malfunctioning winglet.

That's a fair enough criticism, but airline levels of safety in any vehicle that has to go through re-entry is not something I think is possible in the foreseeable future. The nature of re-entry is not very gentle. If you lose pressure in an aircraft, the oxygen masks drop and the pilot dips down to safer altitudes. You lose pressure in a re-entry vehicle, your passengers are dead, and you're lucky if the ship lands in less than 10,000 pieces. 

Link to comment
Share on other sites

9 minutes ago, Raven Industries said:

You lose pressure in a re-entry vehicle, your passengers are dead, and you're lucky if the ship lands in less than 10,000 pieces. 

If there are no other major failures, losing pressure during reentry is likely survivable as all crew and passengers will at least have sufficient gear to provide breathing gas down to landing.  The failure of Soyuz 11 saw to that.

Link to comment
Share on other sites

1 hour ago, sevenperforce said:

Having four means that if one becomes locked, the other three can compensate. 

A fin locked at max/min will affect the drag coefficient a lot, and basically your passengers experience a heck ton of gees. (good for kerbal contracts.)

If the stuck fin is upper fin, you might not be able to maintain a high enough angle of attack that the heat shield works. Basically, it will burn.

Edited by Xd the great
Link to comment
Share on other sites

11 hours ago, Xd the great said:

A fin locked at max/min will affect the drag coefficient a lot, and basically your passengers experience a heck ton of gees. (good for kerbal contracts.)

If the stuck fin is upper fin, you might not be able to maintain a high enough angle of attack that the heat shield works. Basically, it will burn.

The actual math is rather extraordinarily complicated, but a back-of-the-envelope approach suggests that even with any one control surface locked at max/min, the other three have sufficient authority for sustainable roll and pitch control, and yaw can be handled with thrusters. The only edge case might be an aft flap (or Plasma Deflector Shields as I prefer to call them) locked in the full-forward position...that's tricky.

In such a situation (e.g., the port aft PDS locked in full-out position), the SS might need to roll the entire vehicle to starboard to effectively "flap" that fixed surface back. For aerodynamic purposes, having both port flaps full-out and both starboard flaps full-back is not very different from having all flaps feathered halfway back.

Link to comment
Share on other sites

Just now, RealKerbal3x said:

Weird how they haven’t installed the flaperons before stacking, like they did previously...

I don't think they are stacking it. I think they are moving it.

(either to the launch site area, or someplace else to facilitate putting the flaps back on definitively)

PS-meaning move it in 2 parts. Tall enough as it is.

Link to comment
Share on other sites

15 hours ago, Jacke said:

If there are no other major failures, losing pressure during reentry is likely survivable as all crew and passengers will at least have sufficient gear to provide breathing gas down to landing.  The failure of Soyuz 11 saw to that.

That was a valve failure, I'm thinking more along the lines of a hole in your fuselage. 

Link to comment
Share on other sites

1 hour ago, Raven Industries said:

[ Soyuz 11 ] was a valve failure, I'm thinking more along the lines of a hole in your fuselage. 

I agree.  But when it's just stated as loss of pressurization, I think the difference needs to be emphasized.  Losing pressurization with minimal other effects is survivable.  Damage affecting the aerodynamics and/or allowing hot reentry gases into the airframe are almost always going to result in LOCV.

 

12 hours ago, mikegarrison said:

I think the F-15 had a few things in its favour.  One, the ruggedness of a military airframe also with a greater range of thrust and control.  Two, the amount of body lift meant even after losing a wing, restoring lift sufficiently was within the range of thrust.  And three, a design close to neutral stability (like all military jets) meant that the remaining control surfaces had enough authority to maneuver sufficiently.  Still, an awesome display of piloting.

Edited by Jacke
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...