A Video Analysis of the SpaceX Falcon 9 Firexplanomaly
Video Caption: A more detailed analysis of the spacex falcon 9 rocket explosion.
Several interesting details. Firstly the main explosion is actually from the fuel from the second stage and the liquid oxygen from the first stage.
In order to save weight on the rocket the second stage of the falcon 9 uses a common wall for the liquid oxygen and fuel tank (rp1). Any rupture in this tank wall would doom the rocket.
The quiet ‘pop’ may well be a failure of a helium tank. They are usually used to keep a pressure in the tanks while they are emptying due to the rocket burning the fuel. If one of these had ruptured while the oxygen tank was full, it could have overpressurized the tank causing it to also fail.
17 responses to “A Video Analysis of the SpaceX Falcon 9 Firexplanomaly”
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Mr. Musk mentioned they were looking at a very narrow time window and nothing was obvious in the telemetry. One would think the helium tank hypothesis would occur over a longer time period and be evident in tank pressure readings.
A bursting helium tank should be extremely obvious in the telemetry, and not consistent with the event starting as a bright explosion.
exactly, and SX has not released any data that shows that.
There is plenty of room on the lightning towers for cameras and microphones. Just ensure that they are earthed.
If memory serves, I recall seeing video of fueling operations on Falcon 9 rockets taken by cameras much closer to this video.
They’ve shown video from cameras on the rocket, looking down past the umbilicals, directly at the area where this event started. But telemetry bandwidth is finite, and they likely switch between cameras…the perversity of the universe being what it is, they’d probably just switched away from anything that’d be useful.
Cameras, and other sensors, on the lightning towers are not weight critical so they can have their own cables and recording devices. So no need to save telemetry bandwidth by multiplexing them.
http://spaceflight101.com/f…
That’s the last frame before the explosion. No significant changes from the frames before it. The clouds of vapor don’t even move much, the biggest difference between the two frames before the first frame showing the explosion is shimmer from atmospheric refraction.
The common bulkhead seems an unlikely cause. It’s a critical area that’s relatively easy to inspect during manufacture, had been thoroughly tested, and is built to handle much greater stresses than the vehicle was under at this point. And a leak would cause obvious pressure changes in the tanks…even a small LOX leak into the RP-1 tank would cause a large increase in pressure as it vaporized, at a time when the RP-1 tank wasn’t supposed to be experiencing any major pressure changes.
To me, the apparent absence of a “smoking gun” in rocket telemetry data indicating any kind of anomaly, like pressure changes or other sound-related event means only one thing: the problem occurred in the strongback systems or at least close to the umbilicals feeding the rocket.
There may have been a slow leak of LOX from the very beginning of the fueling that is not evident in telemetry. They should compare this test’s pressure vs flow rates with past fueling telemetry. Doug’s focus on the common wall may be correct if the leak was imperceptible in telemetry. Compare with past telemetry. If it’s the 2nd stage design again, RTF in Nov is unlikely.
I saw this in an earlier close-up. If you look closely between the second and third blue lines, you can just see one of the fill lines change shape a fraction of a second before the explosion. It seems to either expand or drop slightly. Look at it carefully several times and see if you can see it. Maybe it’s just in my feeble brain.
The common bulkhead is that failed is between the LOX and kerosene tanks in the 2nd stage. There is an inter-stage between the 1st and 2nd stages. The 1st image shows the LOX gushing from 2 round ports. Just LOX, no fireball. It is dark. The fairing is not lit up. The very next frame shows the ignition. The tail extending down may be kerosene. The 2 ports are blow out ports to release LOX in case of an over pressure. It almost worked. It is possible there would not have been a fire ball. But when the over pressure happened, it blew the common bulkhead, over pressuring the kerosene tank and LOX mixing and a spark and ignition. The pop was the helium tank rupture. Musk said it sounded like a weld tearing. The sound was several seconds before the explosion. SpaceX saw the pressure rising in the tank. There was nothing they could do about it. If a crew capsule it would have time to abort when the pressure started rising. That is why Musk said it would have made it. The same thing might have happened in the first explosion, not a strut failure. SpaceX cannot make helium tanks. If anyone wants to use SpaceX they should go to the old outside supplier and have SpaceX install it. The 1st image proves it was an over pressure.
The images were made with ImageGrab. Frame by frame and frame grab. I took several AVI videos of the screen. It was 30FPS. The original video may have been 40FPS. The monitor is 60FPS. Because of the different frame rates, some frames from the original video are left out. If you want to check on me several videos has to be made and it may be by chance you get the images shown here. I sent NASAwatch and SpaceX the AVI video I made. ImageGrab is available at their website. It is free.
I never thought I would see LOX gushing out of a rocket.
Did you seriously just take video of a monitor and present the result as an attempt at image analysis? All you’ve done is make an extremely lossy copy of the video which fails to accurately reproduce the start of the fireball. That’s fire, the image mangled by your mistreatment of the video, not a plume of LOX, and the rest of your post is fantasy contradicted by the available evidence.
The original video is 60 fps. This is the first frame showing the explosion:
http://spaceflight101.com/f…
whether it was helium tank rupture, or strut failure, it would show a similar sensor readings of LOX tank building up pressure. SX talked about that happening the first time around, but did not speak of it this time.
Has SX released log files?
https://uploads.disquscdn.c… https://uploads.disquscdn.c… https://uploads.disquscdn.c… https://uploads.disquscdn.c…
This sequence is a slightly better. Look at the logo on the fairing. 1=not lit,2=a little lighter, 3=same as 2, 4=well lit. There is a flash at 2. I have no theory what that is.
So? Your approach is fundamentally flawed. Your results are meaningless garbage, no matter how many times you repeat the process. The only thing you are doing is producing degraded reproductions of a YouTube video.
The fact is that the explosion appears as a bright fireball in the very first frame where it is visible. There is no further information to be revealed by fooling around with pointing a camera at the screen.
OK well I guess I take it all back. Good Call Doug Messier.
http://www.spacex.com/news/…
” At this stage of the investigation, preliminary review of the data and debris suggests that a large breach in the cryogenic helium system of the second stage liquid oxygen tank took place. All plausible causes are being tracked in an extensive fault tree and carefully investigated. Through the fault tree and data review process, we have exonerated any connection with last year’s CRS-7 mishap.”