19 Apr 2024, 07:18 [ UTC - 5; DST ]
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Post subject: Re: Starship SN-10 - Landed Okay-ish, then the KABOOM Posted: 30 Mar 2021, 14:49 |
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Joined: 04/26/13 Posts: 19903 Post Likes: +19620 Location: Columbus , IN (KBAK)
Aircraft: 1968 Baron D55
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Username Protected wrote: SN11 exploded when they attempted to relight the engines at 1 km AGL. Yep, and no video of it because the visibility was about zero/zero at the pad. Something unfortunate went wrong well before the flip was completed. I think it would be useful if we had been able to see it.
_________________ My last name rhymes with 'geese'.
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Post subject: Re: Starship SN-10 - Landed Okay-ish, then the KABOOM Posted: 30 Mar 2021, 18:56 |
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Joined: 11/30/10 Posts: 4263 Post Likes: +3718 Company: Flagstaff-Williams Dev. LLC Location: KCMR
Aircraft: 1965 310J
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Trends being the game; it looks like flight control isnt thier problem; Engine control. maybe more time on the test stand.
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Post subject: Re: Starship SN-10 - Landed Okay-ish, then the KABOOM Posted: 30 Mar 2021, 21:33 |
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Joined: 12/10/07 Posts: 8005 Post Likes: +6883 Location: New York, NY
Aircraft: Debonair C33A
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Username Protected wrote: Yep, and no video of it because the visibility was about zero/zero at the pad. Something unfortunate went wrong well before the flip was completed. I think it would be useful if we had been able to see it. Yes, I am rather perplexed they choose to launch in zero/zero conditions. I understand the systems don't care about the visibility - but this is a test for God's sake, don't you think you'd want to see what is happening if things don't go as planned?
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Post subject: Re: Starship SN-10 - Landed Okay-ish, then the KABOOM Posted: 30 Mar 2021, 22:30 |
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Joined: 12/07/17 Posts: 7035 Post Likes: +5807 Company: Malco Power Design Location: KLVJ
Aircraft: 1976 Baron 58
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Username Protected wrote: Yep, and no video of it because the visibility was about zero/zero at the pad. Something unfortunate went wrong well before the flip was completed. I think it would be useful if we had been able to see it. Yes, I am rather perplexed they choose to launch in zero/zero conditions. I understand the systems don't care about the visibility - but this is a test for God's sake, don't you think you'd want to see what is happening if things don't go as planned?
SpaceX likely saw everything. They’ve got cameras and telemetry up the yin yang. Some European hackers have managed to get the Falcon feeds (turns out you’re actually not allowed to encrypt the telemetry coming off of a peaceful rocket, something in a treaty between the US and USSR).
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Post subject: Re: Starship SN-10 - Landed Okay-ish, then the KABOOM Posted: 31 Mar 2021, 10:02 |
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Joined: 04/26/13 Posts: 19903 Post Likes: +19620 Location: Columbus , IN (KBAK)
Aircraft: 1968 Baron D55
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Username Protected wrote: SpaceX likely saw everything. They’ve got cameras and telemetry up the yin yang. Some European hackers have managed to get the Falcon feeds (turns out you’re actually not allowed to encrypt the telemetry coming off of a peaceful rocket, something in a treaty between the US and USSR). Yeah, those folks who captured the Falcon 9 feeds did some slick work. Very cool to see the video feed. The telemetry of course is harder to decode, I don't think they've done that. On the SN11 flight their video feed was terrible. They lost several camera feeds, and the rest were constantly dropping off. Something wasn't working well. They don't put those cameras on there for our entertainment; they presumably provide information that SpaceX wants to gather and losing the feed like that is concerning. I assume, and hope, that their actual telemetry feed is more robust, but visual evidence is something different and many times will quickly point to a problem or narrow down the search. There has been a lot of noise about cameras in the cockpit for NTSB investigations. While I don't support the idea, I agree that having video of an event can provide depth and context to what happened in a way that only visual evidence can. Three hours after launch, the fog was gone and the sky was clear. Like a pilot launching into similar conditions I have to ask "why the rush"? Edit: Looking at the weather for Boca Chica I think I know the answer: Wind. By the time the time the fog cleared the wind had gone from around nine knots to over twenty five with ten or fifteen knot gusts and stayed like that for the rest of the day. It was launch in the fog or scrub. So why not scrub? I'll go into speculation mode for a minute: I think that what they intended to learn from the first generation of Starship prototypes has already been accomplished. They are ready to move on to Gen 2 which begins with SN15, the next to fly. I think they didn't care whether 11 landed or not and so essentially shot it off as much to get rid of it as anything else. In the process they got some more flight data and probably got some good engine data, which it seems they desperately need. The rest is just the now routine cleanup and move on.
_________________ My last name rhymes with 'geese'.
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Post subject: Re: Starship SN-10 - Landed Okay-ish, then the KABOOM Posted: 31 Mar 2021, 10:57 |
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Joined: 12/03/14 Posts: 19252 Post Likes: +23622 Company: Ciholas, Inc Location: KEHR
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Username Protected wrote: I think they didn't care whether 11 landed or not and so essentially shot it off as much to get rid of it as anything else. Three Raptor engines are not for nothing, so I don't buy the "waste it" explanation. Much of the problem seems to be from starting engines in a horizontal position. Probably lots of fuel slosh problems from the reorient effort. Why not use the flap fins to get the rocket more upright and then start the engines? They seem to start well in that position and perhaps this saves weight on the systems (like header tanks) trying to compensate for the horizontal start position. Mike C.
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Post subject: Re: Starship SN-10 - Landed Okay-ish, then the KABOOM Posted: 31 Mar 2021, 11:02 |
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Joined: 05/17/10 Posts: 4418 Post Likes: +1727 Location: canuck
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https://www.spaceflightinsider.com/miss ... -maneuver/Quote: It’s unclear whether that explosion was from a Raptor or the vehicle’s flight termination system. What is clear, however, is Starship SN11 did not come close to landing and instead performed a “rapid unscheduled disassembly”, or RUD.
_________________ nightwatch...
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Post subject: Re: Starship SN-10 - Landed Okay-ish, then the KABOOM Posted: 31 Mar 2021, 11:10 |
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Username Protected wrote: Much of the problem seems to be from starting engines in a horizontal position. Probably lots of fuel slosh problems from the reorient effort.
Why not use the flap fins to get the rocket more upright and then start the engines? They seem to start well in that position and perhaps this saves weight on the systems (like header tanks) trying to compensate for the horizontal start position. I see your point and I have a feeling they're looking closely at this. Probably a better way to look at it is which way is the acceleration vector when they're restarting the engines, not necessarily the same thing as the rocket's orientation with the surface of the earth.
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Post subject: Re: Starship SN-10 - Landed Okay-ish, then the KABOOM Posted: 31 Mar 2021, 11:16 |
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Joined: 10/31/14 Posts: 534 Post Likes: +255
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If you watch the video on a big screen then you can see fire where it doesn’t belong on the ascent It’s my guess that’s what caused the boom
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Post subject: Re: Starship SN-10 - Landed Okay-ish, then the KABOOM Posted: 31 Mar 2021, 11:39 |
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Joined: 02/10/12 Posts: 6827 Post Likes: +7937 Company: Minister of Pith Location: Florida
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Username Protected wrote: I think they didn't care whether 11 landed or not and so essentially shot it off as much to get rid of it as anything else. Three Raptor engines are not for nothing, so I don't buy the "waste it" explanation. Much of the problem seems to be from starting engines in a horizontal position. Probably lots of fuel slosh problems from the reorient effort. Why not use the flap fins to get the rocket more upright and then start the engines? They seem to start well in that position and perhaps this saves weight on the systems (like header tanks) trying to compensate for the horizontal start position. Mike C. No baffles in the fuel tanks? Pressurization?
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Post subject: Re: Starship SN-10 - Landed Okay-ish, then the KABOOM Posted: 31 Mar 2021, 11:40 |
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Joined: 05/17/10 Posts: 4418 Post Likes: +1727 Location: canuck
Aircraft: x23mouse
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Username Protected wrote: If you watch the video on a big screen then you can see fire where it doesn’t belong on the ascent It’s my guess that’s what caused the boom Quote: Musk later elaborated that engine No. 2 appeared to have issues during the ascent and didn’t reach operating chamber pressure during the landing burn.
However, the plan was for all three Raptors to ignite initially with the least-desirable engine to immediately shut down. So in theory, Musk said, that engine wouldn’t have been needed anyway.
_________________ nightwatch...
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Post subject: Re: Starship SN-10 - Landed Okay-ish, then the KABOOM Posted: 31 Mar 2021, 11:44 |
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Joined: 03/23/08 Posts: 6945 Post Likes: +3602 Company: AssuredPartners Aerospace Phx. Location: KDVT, 46U
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Username Protected wrote: No baffles in the fuel tanks? Pressurization? They have isolated header tanks like aerobatic aircraft (sans flop tube though)...
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Post subject: Re: Starship SN-10 - Landed Okay-ish, then the KABOOM Posted: 31 Mar 2021, 13:14 |
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Joined: 04/26/13 Posts: 19903 Post Likes: +19620 Location: Columbus , IN (KBAK)
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Username Protected wrote: Three Raptor engines are not for nothing, so I don't buy the "waste it" explanation.
Much of the problem seems to be from starting engines in a horizontal position. Probably lots of fuel slosh problems from the reorient effort.
Why not use the flap fins to get the rocket more upright and then start the engines? They seem to start well in that position and perhaps this saves weight on the systems (like header tanks) trying to compensate for the horizontal start position. I was exaggerating slightly when I implied that they were just tossing it away. I'm sure that they had some reason to fly it that added value to the program. Just avoiding the cleanup afterward, and as you say, the cost of the Raptors would be reason enough to not fly if there was no value. I do think that they're at the point where they're done with Gen 1 and are ready to move on. They designed the header tanks to address the problem with fuel un-porting when transitioning from horizontal to vertical. Their smaller size is to provide for continuous flow in either orientation, and they are pressurized by a "head" of gaseous material (fuel or oxidizer) that builds up above the liquid level and is replenished by a return flow from the Raptors. The trouble they seem to have is that during the flip, the gaseous part gets tossed around with the liquid, causing the gas to "collapse" back into liquid, taking the head pressure with it. That's why they tried using Helium as a substitute. They may have worked that out in Gen 2 (SN15-19), or not. Solid rocket motors dedicated to the flip are expensive, add weight and complexity, and take up space in the engine bay that they don't really have. From a SpaceX perspective of "less is more", they're a non-starter. I'm especially curious about this deconstruction because all evidence points to it occurring long before ground contact. I do not believe that it was initiated, I think something went very wrong right after the engine start was initiated. Video would have helped to understand it. Maybe the upward facing pad camera got a view of it looking straight up.
_________________ My last name rhymes with 'geese'.
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