Did anyone notice the shift in the stack fairly early on? The entire stack rocked by about a foot or two, accompanied by a loud metallic boom. It's apparently something to do with locking the stack in place, but that must be pretty disconcerting to watch happen in person. I'm a little surprised that such an energetic motion is acceptable. Rocking the entire stack must involve a lot of energy. That can't be good for any of the hardware involved.
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SpaceX Starship - Integrated Flight Test #2 - Starbase TX - Including Post Launch Dissection
- Thread starter Grendal
- Start date
I did not. Can you estimate about how long after the ship touched the booster that occurred? I’d like to see it.
Here's a link to the point in the NasaSpaceFlight video. 2:20:00 CDT. After watching it a few times, it looks like the Starship wasn't properly seated, and it all wobbled when they shifted it a bit to correct it. Or they were just waiting a long time to lower the Starship the final few inches. Unfortunately the LabPadre camera doesn't really show much because of the angle.
After watching it a few times, I'd say it dropped a bit. I'd go with a final lowering as the reason.
It's likely impossible to get the two mating surfaces parallel before final seating, so there will be some radial torque load and rotation at the end. Like setting a glass on a counter, one edge touches first then the other hits along with the full circumference.
I was mightily worried, in the early days, during a launch - will this thing topple even before it clears the pad ?
And now that worry has increased an order of magnitude with Starship. That things is so tall, so heavy and the engines are all pushing from the very bottom.. Try lifting a tall heavy iron rod from the bottom surface. I watched the first FH launch live in person in FL along with 1000 other people and with Billy Nye the chief guest. When everyone was clapping and hollering, I was clutching the iron rails and praying..
And now that worry has increased an order of magnitude with Starship. That things is so tall, so heavy and the engines are all pushing from the very bottom.. Try lifting a tall heavy iron rod from the bottom surface. I watched the first FH launch live in person in FL along with 1000 other people and with Billy Nye the chief guest. When everyone was clapping and hollering, I was clutching the iron rails and praying..
I drift uncomfortably between two mindsets.
1. They're amazing engineers with computer simulations and the latest in materials science. NASA put Saturn V into orbit using slide rules.
2. I sure hope it doesn't fall over and blow up.
Sounds like your typical rocket to me, just scaled up.
I never had that concern with IFT-1 and still don’t. Actual rocket scientist have figured it out. It’s not going to just fall over as it clears the tower. Remember, if for some reason too many engines fail to ignite or to reach full power the control software will shut everything down and not release the OLM clamps. In addition, 13 of the engines can TVC as needed.
I have very high confidence that IFT-2 will reach the point where stage sep is initiated. After that point, we shall see…
The tallness and weight don't matter as long as a >1g center of thrust is radially aligned, behind the center of mass. And if the center of lift is also behind the center of mass, then the rocket will be dynamically stable.
ZenRockGarden
Active Member
It's certainly bigger and heavier, but in the world of making-rockets-go-straight it turns out taller is better. Little shorty things tumble easier while having mass up high in the nose is unintuitive but helpful.
Interesting.. I would have never thought that would be case. Will try to read up more on that.
Look up "inverted pendulum" , it has to do with moment of inertia.
Raptor performance during the last static fire was all engines ignited, two shut down early. That is enough to get the vehicle to stage sep assuming only one or two (or even more?) additional Raptors shut down before that point.
So in that sense the static fire was a success though as you note it was not perfect. But perfection is not always necessary for IFT-2 to proceed.
That does make sense. I expect some of the reasons it may, or may not, happen will be discussed in the NSF video I posted earlier. I expect those people have a better understanding of the details than we do... Maybe.
Having balanced things like a top-heavy broom on my hand, I agree.
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