Author Topic: SpaceX Falcon 9 : CRS-16 (Dragon SpX-16) : December 5, 2018 - DISCUSSION (Read 255692 times)

EnigmaSCADA · « **Reply #140 on:** 12/05/2018 05:43 pm »

Everyday Astronaut played a video of it a few minutes ago. Looked wild and then much calmer as landing burn started.

Lars-J · « **Reply #141 on:** 12/05/2018 05:43 pm »

Amazing to almost recover...

Mongo62 · « **Reply #142 on:** 12/05/2018 05:44 pm »

Quote from: kessdawg on 12/05/2018 05:43 pm

Crazy!

https://twitter.com/elonmusk/status/1070387162892259329

Time enough to refurbish for the in-flight abort?

OxCartMark · « **Reply #143 on:** 12/05/2018 05:44 pm »

Quote from: rockets4life97 on 12/05/2018 05:34 pm

No explosion in the video posted above on landing. That is impressive.

There was smoke just above the trees on the right immediately after. Where there's smoke there's fire they say. And if not an explosion at least there would be a bursting of the pressurized tanks. What seems to be missing is the COPVs taking flight as we've seen before.

Betcha the folks at Vandenburg that prevented SSO-A from coming down near NROL-71 are feeling justified right now.

DigitalMan · « **Reply #144 on:** 12/05/2018 05:45 pm »

Quote from: deruch on 12/05/2018 05:42 pm

Quote from: OnWithTheShow on 12/05/2018 05:39 pm
This gives gives some evidence to the thread on whether stages target to undershoot, overshoot, or center the pad and then vector in after landing burn start up. It seems they may target an undershoot.
Or it successfully achieved a divert.

I was watching with my binoculars until it got very low where my view was blocked. It did not look like there was any kind of divert. I conclude it probably targeted an undershoot and would have had to do a maneuver somewhere to vector over to the landing pad.

bdub217 · « **Reply #145 on:** 12/05/2018 05:45 pm »

At what point when you don't have complete control of your rocket flying back toward land does range safety kick in? While i'm sure they are happy they got their rocket back (albeit a little wet) I expect we will need to be asking some questions about whether the automated flight termination system worked as it was designed - and if it did - who didn't trigger a manual termination and why not? Dangerous as hell.

Roy_H · « **Reply #146 on:** 12/05/2018 05:45 pm »

So, did the first stage have enough control left to deliberately divert to the ocean, or was the original trajectory to the ocean with a planned divert to the landing pad only if all was ok?

Sorry for posting this in Updates, I thought I was in Discussion.

ZachS09 · « **Reply #147 on:** 12/05/2018 05:46 pm »

Quote from: Norm38 on 12/05/2018 05:28 pm

Crazy, that's the first failed landing since June of 2016.

Actually, the first landing failure since the Falcon Heavy center core’s landing failure, as that is technically based off of F9 technology.

ClayJar · « **Reply #148 on:** 12/05/2018 05:47 pm »

When the roll seemed to drastically accelerate right around the time they called transonic, the upper right grid fin in the frame appeared to be hard-over (due to hydraulic pump stall, apparently). Would that suddenly greater rotation be a logical result of transonic choking of the flow in the grid fins, meaning the grid fin instead of working to slow the rotation would be acting more like a solid paddle and doing the opposite?

Lars-J · « **Reply #149 on:** 12/05/2018 05:47 pm »

Quote from: bdub217 on 12/05/2018 05:45 pm

At what point when you don't have complete control of your rocket flying back toward land does range safety kick in? While i'm sure they are happy they got their rocket back (albeit a little wet) I expect we will need to be asking some questions about whether the automated flight termination system worked as it was designed - and if it did - who didn't trigger a manual termination and why not? Dangerous as hell.

This has been discussed previously, but let me re-iterate:

1. The end of the boost-back puts it on a trajectory that targets the ocean. (we just saw this)
2. The grid fins (if they work) move the impact/landing point to the pad or just past it.
3. The landing burn aims at the pad.

OxCartMark · « **Reply #150 on:** 12/05/2018 05:47 pm »

Quote from: matthewkantar on 12/05/2018 05:37 pm

Last words from the SpaceX launch host before the stage diverged: "It is SO exciting along the Space Coast!"

My last words before - "they've really got this landing thing down like clockwork, Sammy" (dog).

Sorry, it was me that caused it.

ugordan · « **Reply #151 on:** 12/05/2018 05:48 pm »

Quote from: Roy_H on 12/05/2018 05:45 pm

So, did the first stage have enough control left to deliberately divert to the ocean, or was the original trajectory to the ocean with a planned divert to the landing pad only if all was ok?

All evidence, including visual, from previous missions suggest it flies a lifting entry from after reentry burn till landing burn. Once 3-axis control was lost, the lift was lost as well.

Frankly, I'm surprised the AFTS didn't terminate and it still executed a soft landing off shore.

chrisking0997 · « **Reply #152 on:** 12/05/2018 05:48 pm »

Quote from: bdub217 on 12/05/2018 05:45 pm

At what point when you don't have complete control of your rocket flying back toward land does range safety kick in? While i'm sure they are happy they got their rocket back (albeit a little wet) I expect we will need to be asking some questions about whether the automated flight termination system worked as it was designed - and if it did - who didn't trigger a manual termination and why not? Dangerous as hell.

IIRC, termination wouldnt be needed if this case. Going in the water is the plan. Its only dangerous if the booster is off the planned path

AC in NC · « **Reply #153 on:** 12/05/2018 05:48 pm »

Quote from: lrk on 12/05/2018 05:44 pm

Booster might still be reused!

https://twitter.com/elonmusk/status/1070387162892259329

Abort test candidate.

tyrred · « **Reply #154 on:** 12/05/2018 05:49 pm »

What manual termination? They use automatic flight termination systems now, no? Don't they safe AFTS for landings? Pretty sure I've heard that call out on landings for a while now. Or maybe I just goes crazy.

tonya · « **Reply #155 on:** 12/05/2018 05:49 pm »

Quote from: EnigmaSCADA on 12/05/2018 05:43 pm

Everyday Astronaut played a video of it a few minutes ago. Looked wild and then much calmer as landing burn started.

It looked like the leg deploy reduced the roll quite swiftly, much like an ice skater but aerodynamic drag may have slowed it more than the shifting weight.

Roy_H · « **Reply #156 on:** 12/05/2018 05:49 pm »

Quote from: bdub217 on 12/05/2018 05:45 pm

At what point when you don't have complete control of your rocket flying back toward land does range safety kick in? While i'm sure they are happy they got their rocket back (albeit a little wet) I expect we will need to be asking some questions about whether the automated flight termination system worked as it was designed - and if it did - who didn't trigger a manual termination and why not? Dangerous as hell.

Why would they blow the rocket up when the trajectory was in the ocean?

Lars-J · « **Reply #157 on:** 12/05/2018 05:50 pm »

Quote from: ugordan on 12/05/2018 05:48 pm

Quote from: Roy_H on 12/05/2018 05:45 pm
So, did the first stage have enough control left to deliberately divert to the ocean, or was the original trajectory to the ocean with a planned divert to the landing pad only if all was ok?

All evidence, including visual, from previous missions suggest it flies a lifting entry from after reentry burn till landing burn. Once 3-axis control was lost, the lift was lost as well.

Frankly, I'm surprised the AFTS didn't terminate and it still executed a soft landing off shore.

They might have if it was heading for land... But they could certainly see its trajectory. Would you prefer to fish up one big thing from the ocean or thousands of pieces of debris?

ugordan · « **Reply #158 on:** 12/05/2018 05:50 pm »

Quote from: bdub217 on 12/05/2018 05:45 pm

At what point when you don't have complete control of your rocket flying back toward land does range safety kick in?

If it didn't exceed the reentry corridor ground track, why would it?

I don't know if roll rate is a consideration for AFTS, though. Seems not.

lrk · « **Reply #159 on:** 12/05/2018 05:50 pm »

Quote from: bdub217 on 12/05/2018 05:45 pm

At what point when you don't have complete control of your rocket flying back toward land does range safety kick in? While i'm sure they are happy they got their rocket back (albeit a little wet) I expect we will need to be asking some questions about whether the automated flight termination system worked as it was designed - and if it did - who didn't trigger a manual termination and why not? Dangerous as hell.

F9 uses AFTS, I don't think there is a manual option anymore. But that is only triggered if the booster deviates more than a set amount from the planned trajectory, and apparently landing a few hundred feet away from the target isn't enough of a deviation. Also I think the last-minute "dogleg" maneuver that put it in the water was automatically triggered when the booster sensed that it wasn't going to make the landing.