Recent Claim by Musk concerning hot 2nd stage start

[bknight]

The ignition after the flip was suspicious.  I believe that they only did it once with starship so in my mind the startup procedure needs to be refined IMO>

[Peter B]

A video recorded in Florida of the flight from the point of the Starship explosion (visible in top left), showing remnants.

[bknight]

A video recorded in Florida of the flight from the point of the Starship explosion (visible in top left), showing remnants.

Only one comment.  It appears that the vehicle is tumbling and yet from BC vantage no tumbling was observed.

[Peter B]

A video recorded in Florida of the flight from the point of the Starship explosion (visible in top left), showing remnants.

Only one comment.  It appears that the vehicle is tumbling and yet from BC vantage no tumbling was observed.

Sorry, not sure I follow. I didn't know there were post-explosion videos of Starship from Boca Chica.

[bknight]

A video recorded in Florida of the flight from the point of the Starship explosion (visible in top left), showing remnants.

Only one comment.  It appears that the vehicle is tumbling and yet from BC vantage no tumbling was observed.

Sorry, not sure I follow. I didn't know there were post-explosion videos of Starship from Boca Chica.

Look at a video more closely you will see the apparent FTS explosion at the back of the stage and then nothing.

[sts60]

I haven’t really followed Starship development.  But it clearly won’t be ready for a nominal 2025* lunar landing mission.  In addition to the vehicle accomplishing the controlled flight profiles that will be necessary, the crew systems will all need to built, integrated, and tested - I have no idea of their development status, but the execrable safety record of Musk-run companies, and my general contempt for Musk as a human being in general and an American in particular, likely colors my uninformed viewpoint.

*I don’t know if that’s still the advertised date.  I’ve been more in the line of discouraging (rather assertively) things from flying, rather than encouraging them to do so, lately.

P.S. (waves) Hi, everybody.

[smartcooky]

A video recorded in Florida of the flight from the point of the Starship explosion (visible in top left), showing remnants.

Only one comment.  It appears that the vehicle is tumbling and yet from BC vantage no tumbling was observed.

Sorry, not sure I follow. I didn't know there were post-explosion videos of Starship from Boca Chica.

I saw somewhere (on Youtube but I cannot remember which channel) that this is a video taken after the RUD not before it, of only part of the top half of the second stage, a piece which survived the explosion, flipping over and over as it fell out of the sky. 

[bknight]

A video recorded in Florida of the flight from the point of the Starship explosion (visible in top left), showing remnants.

Only one comment.  It appears that the vehicle is tumbling and yet from BC vantage no tumbling was observed.

Sorry, not sure I follow. I didn't know there were post-explosion videos of Starship from Boca Chica.

I saw somewhere (on Youtube but I cannot remember which channel) that this is a video taken after the RUD not before it, of only part of the top half of the second stage, a piece which survived the explosion, flipping over and over as it fell out of the sky.

If the RUD was a result in the FTS, then that didn't work so well.  Scott Manley suggested in one of his videos, that there may have been a leak in the oxygen system, look at the oxygen and methane graphs closely, oxygen is GT methane up until almost the RUD, then there was the RUD with oxygen below methane, seemed like a leak fueled the RUD.  But the "upper" portion of the starship seems reasonable. thanks

[Peter B]

And now the fourth flight made it all the way through re-entry to splashdown.

Watching that fin actuate having been essentially burned through was one of the most amazing things I've ever seen - until I saw the telemetry indicated it had splashed down.

I think the last time I was so emotionally affected by something in space and rocketry was the launch of the first Falcon Heavy.

[Zakalwe]

And now the fourth flight made it all the way through re-entry to splashdown.

Watching that fin actuate having been essentially burned through was one of the most amazing things I've ever seen - until I saw the telemetry indicated it had splashed down.

I think the last time I was so emotionally affected by something in space and rocketry was the launch of the first Falcon Heavy.

Epic, wasn't it?

[JayUtah]

I've never before seen anything that so clearly expresses the sheer brutality of re-entry. And yes, I too had an uh-oh moment when I saw the fin root starting to break up. At that point, normally, you just hope it breaks cleanly away and leaves you with a reasonable fallback control regime. To have it still continue to steer the ship as it's falling apart is a testament to robust engineering.

The commentary from our fluid dynamics wonks also included marveling at how uniform the flow was during entry interface. It's just sobering to see in 4K what normally you see only in computer-generated isolines or through tiny windows in hypersonic wind tunnels.

[Peter B]

I've never before seen anything that so clearly expresses the sheer brutality of re-entry. And yes, I too had an uh-oh moment when I saw the fin root starting to break up. At that point, normally, you just hope it breaks cleanly away and leaves you with a reasonable fallback control regime. To have it still continue to steer the ship as it's falling apart is a testament to robust engineering.

The commentary from our fluid dynamics wonks also included marveling at how uniform the flow was during entry interface. It's just sobering to see in 4K what normally you see only in computer-generated isolines or through tiny windows in hypersonic wind tunnels.

It's fascinating to read comments like this from someone who works in the field. Thank you for sharing!

[smartcooky]

I've never before seen anything that so clearly expresses the sheer brutality of re-entry. And yes, I too had an uh-oh moment when I saw the fin root starting to break up. At that point, normally, you just hope it breaks cleanly away and leaves you with a reasonable fallback control regime. To have it still continue to steer the ship as it's falling apart is a testament to robust engineering.

The commentary from our fluid dynamics wonks also included marveling at how uniform the flow was during entry interface. It's just sobering to see in 4K what normally you see only in computer-generated isolines or through tiny windows in hypersonic wind tunnels.

Clearly, they are going to need additional heat shielding in that rear area of the flap.

I am pretty sure the fact that flap survived would mostly down to the fact that SpaceX made the decision to build Starship using 304L stainless rather than the usual aluminium alloys. SpaceX are apparently going to shift the forward flaps leeward "to help improve reliability and ease of manufacturing". I do wonder what effect a change like that would have on control authority, both during launch and ascent, and during the flip maneuver during the landing.

[Zakalwe]

The hinge was an expected trouble spot. It'll be interesting to see how they change the design to cope with it.

[JayUtah]

Discontinuities tend to create hot spots. Wing roots on supersonic aircraft are notorious for this. Sometimes using more robust materials is the answer, such as RCC for the space shuttle leading edges. But more often you can fix it by rearranging the geometry. Moving the flaps is definitely worth investigating, with the noted caveats that handling characteristics will change.