Jump to content

SpaceX Discussion Thread


Skylon

Recommended Posts

Wouldn't something on the outside meant to be a leg, be better suited shaped as a fin than a beam? 

Certainly it will add drag either way - so does the shape matter? 

Also - does SX need permission to attempt a ground landing rather than merely ditch in the ocean?  Or are we speculative about a drone ship landing attempt? 

Edited by JoeSchmuckatelli
Link to comment
Share on other sites

8 minutes ago, tater said:

Maybe it's a fin placeholder?

They had fins that looked like that on the test rig thing they put the nosecone in.

Looks to me like something similar to the jig they use to weld the fin mounts on. Retractable leg mount maybe? I thought they’d be fixed, if anything. 

Link to comment
Share on other sites

10 hours ago, tater said:

Given that the FTS terminates the vehicle automatically if it slightly deviates form the flight path, the hazard area need only contain the actual volume where debris are possible. The areas are 10+ nm on the narrow sides, I doubt debris would be a problem past several hundred meters on either side of the flight path.

The launch hazard areas might still be the same as they were when range control had to decide "manually" to terminate a flight.

10nm is not unreasonable for lateral separation. It's a big planet, and we have lots and lots of airplanes, and they have all learned to stay separated.

I find Musk's repeated whining about safety rules to be troubling.

Link to comment
Share on other sites

7 hours ago, mikegarrison said:

10nm is not unreasonable for lateral separation. It's a big planet, and we have lots and lots of airplanes, and they have all learned to stay separated.

I find Musk's repeated whining about safety rules to be troubling.

I took that statement as an expression of frustration from someone embracing a fail-fast philosophy encountering real-world processes that do not support that philosophy.

I am sure it does not help that it is probably expensive to scrub when otherwise ready to launch. 

Link to comment
Share on other sites

6 hours ago, mikegarrison said:

10nm is not unreasonable for lateral separation. It's a big planet, and we have lots and lots of airplanes, and they have all learned to stay separated.

Yes, but if a NOTAM is issued, who should be responsible? Seems like you could have some zone far closer to the actual danger area which results in a scrub, and another wider area that results in a stiff fine or some sanction for the violator. If the actual plausible danger area is 1-2 nm wide, that's the scrub area, anyone enters that, and scrub. If anyone enters the wider separation area (whatever it might be called), they have endangered themselves, and are subject to a fine, possible loss of license, etc., but the launch proceeds. Note that these would be set so the actual chance of a poor outcome is incredibly unlikely.

This is already in place to some extent, as the hazard areas end not that far downrange, at which point the vehicle could still rain down debris if there was a RUD, it's just incredibly unlikely to hit anything.

 

6 hours ago, mikegarrison said:

I find Musk's repeated whining about safety rules to be troubling.

In this case we don't know what the actual issue was, though it seems to have been a helicopter operating very close to where crowds of people were watching the launch anyway—presumably a safe location. More importantly, I would assume that the hazard areas are sized as a function of not just rocket debris danger area, but also aircraft velocity. The area is not variable in time, it's a shape that is static during the launch, because a plane could enter the area at the beginning of the launch someplace that there is ZERO risk at liftoff (say 50nm downrange) but then be a real problem as the plane continues to violate towards the flight path of the rocket some seconds after launch when the rocket is then above the aircraft. You can't give planes wobbly NOTAMs that vary in real time, though, too confusing. In this case, if it was a hovering helicopter, it seems like there's zero chance that it could possibly be at risk due to it continuing to move into the flight path of the rocket.

You could look at the trajectory of the aircraft on a radar track, and compare vs rocket flight path the same predicted value in the future and rule out risk in real time to allow a launch. On the current track the helo might move a few hundred m towards the flight path before liftoff, and it's still well outside any actual hazard area, so "go" for launch (helo gets fined for violating restricted area). Downrange a jet enters the very edge on a flight path that has it crossing the rocket path XX seconds after launch with current track moved forward those XX seconds from launch and IS at actual risk. Scrub. Seems like it's more rule of thumb based now than data based.
 

Link to comment
Share on other sites

Perhaps the time honored routines need updating, instead of the (paraphrased) binary approach:

"Payload?" - "Go!"
"Vehicle?" - "Go!"
"GSE?" - "Go!"
"Range?" - "Range is RED. Repeat, Range is RED!"

Perhaps Range could use a more real-time risk-assessment approach. But when lives are on the line, changing what is known to work is inherently risky and must be considered very carefully indeed. :shrug:

Link to comment
Share on other sites

14 minutes ago, NFUN said:

It took me way too long to parse that "nm" in this context is "nautical mile". Kept wondering why barely-measurable lengths were relevant

I went to nautical miles because it was in the post I was replying to (and might very well be the FAA requirement for units).

In a space context real nm have very little utility outside wavelengths, hehe.

Also:

 

Link to comment
Share on other sites

31 minutes ago, NFUN said:

It took me way too long to parse that "nm" in this context is "nautical mile". Kept wondering why barely-measurable lengths were relevant

Yes, this can be a confusion issue. I often use nmi, for that reason. I guess I didn't this time, though.

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...