News Changes to the SpaceX BFR rocket.

jedidia

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Soooo... I assume the second stage was supposed to separate before the booster started to flip? Because the commentator made it sound as though it was expected for the thing to flip while still in one piece...
 

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Well, it did better than the N-1. Dropped six engines but kept pushing down range. Losing five of those engines on the outer ring probably caused some big turning moments. I'm not sure which engines gimbal on the current engine configuration, and I'm not sure how they control roll except for maybe the gas thrusters that were going like mad.

I love how we had live footage of the interstage while the rocket was tumbling out of control. Somewhat amazed it managed to tumble like that without tearing apart, even in the upper atmosphere. SpaceX hopefully has lots of data available to them that will let them figure this out. I love that they are willing and able to actually flight test stuff to failure to figure out the bugs. There really isn't a better way to do it.
 

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As long as it was still driveable I'd leave that damage.

"What happened to your car?"

"Rocket blast damage. 😎"

EDIT: I hope that was rock and not concrete spalled off the pad.

Or rocket engine parts. Or propellant, for the Raptors.
 

diogom

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Soooo... I assume the second stage was supposed to separate before the booster started to flip? Because the commentator made it sound as though it was expected for the thing to flip while still in one piece...
I think the plan was to separate with spin, with no mechanical pushers. Though of course the separation is supposed to happen right away, ship igniting its engines and stopping the rotation while the booster continues the flip to start the boostback.

I wonder if it was due to altitude, I think it was less than half as high as it was supposed to be? Anyway, honestly impressed it made it that far with 6 engines out, that alone I think puts it past N1 at its best. For a first ever flight of a vehicle like this, I wouldn't call this outcome trivial, considering how many first flight failures we've seen recently from companies with a lot more at stake (and payload on board) and more mature designs. And the expectations have been at "just clear the tower and GSE" for over a year. It's somewhat disappointing the engines still took a hit this big, but when they have the next booster and ship iteration built with several design improvements and collecting dust waiting for their testing campaigns, it is what it is. Hopefully the pad wasn't nuked too hard, seeing some ideas that concrete blast might have taken out the initial 3 engines. Either way, it was looking before that there would be a lot of work done to it before the next flight, with continuing the water deluge, more shielding and recently, parts labelled "flame diverter" have started arriving.
 

GLS

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Anyway, honestly impressed it made it that far with 6 engines out, that alone I think puts it past N1 at its best.
If I remember from past readings, the first and second N1s lost one engine each, leading to fire and... sort of like what we saw today. The third was loss of control not related to engines issues, and the last was prop line overpressure after the center engines shutdown, resulting in kaboom. After 1 launch, I place it right next to the N1.
 

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It will be interesting to know the distribution of the causes of the engine kaputs between internal engine issues, engines next to other engines, other rocket systems, and external debris from the ground.
 

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I'm shocked it made it as far as it did, it was shedding parts all along its flight. Multiple engines failed and it looks like exhaust from some in quite a bit different. I wonder if RSO blew it up or what.

The last part is for sure. It was too late for second stage ignition.
 

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Look at the debris hitting the water. Fairly dramatic tower avoidance maneuver... or tilting because of engines going out?


A full-screen view of the engines during the launch:
1682017168576.png


Only now did I notice the engine graphics on the bottom left... :cautious: at the time I was barely glancing at the altitude and velocity.
So, there are more engines out than the graphics show (and other views later show 2 more engines out, both adjacent to other dead engines, which didn't show up in the graphics), which coupled with the visible fire, makes me believe that wiring was being burned and they were losing engine data. The loss of control probably was caused by the TVC wiring shorting and/or going dead. If it had a KORD, this would be called the N2.
Also, a large chunk of something, several meters long, came up the side of the vehicle as it left the pad.
 

diogom

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The loss of control probably was caused by the TVC wiring shorting and/or going dead
If that wasn't it, it's looking like they lost both hydraulic power units for good measure, so in theory TVC is lost completely. They're at the bottom near the engines, same sides as each grid fin pair, maybe those were (one of) the stuff falling off.
 
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Urwumpe

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Nowadays the RSOs are going out of business. Like other rockets, this has an autonomous FTS.

Not that automatic, a fully automatic FTS would have triggered at least when it cartwheeled, earliest when the roll channel saturated.
 

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Not that automatic, a fully automatic FTS would have triggered at least when it cartwheeled, earliest when the roll channel saturated.
Maybe it just looks at the coordinates of the IP, and as far as it stays inside the prescribed area, it can do all the gymnastics it wants?
 
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