How My Rocket Failed | SAROS Episode 2
ฝัง
- เผยแพร่เมื่อ 25 มิ.ย. 2024
- My third and final flight of CASCADE both burned its motor and went nowhere. So instead of discussing 360 camera stuff & chute configuration improvements, we have an anomaly investigation. We do BOTH a direct cause analysis and root cause analysis. It's a doozie.
ALSO I forgot to put George L. in the credits for helping with the fishbone diagram! Thank you!!
See if you can find the doggo :)
Chapters:
0:00 Intro
1:20 Initial Evidence Review
4:12 Timeline (with jazz)
5:54 5 Faults
6:49 Solid Rocket Motor Description
10:43 Good GIF (then grain shapes)
11:45 Welcome back! This part is important
12:33 Direct Cause Analysis Pt. 1
16:08 Ignition description
18:52 Ignition failure
22:07 Direct Cause Analysis Pt. 2
24:03 Motor case failure
25:57 Nozzle failure
27:45 Best Guess Timeline
29:25 Direct Cause Analysis Pt. 3
31:45 Root Cause Analysis
32:55 People
34:43 Methods
35:59 Materials
36:58 Environment
37:33 Outro
Music:
www.epidemicsound.com/playlis... - วิทยาศาสตร์และเทคโนโลยี
Joe: "send it"
Andrew: "maybe use a different igniter"
Joe: "send it"
Jokes aside, these technical videos are super informative, and the errors are sometimes a lot more informative than the successes. Can't wait to see future SAROS updates
This is your best video yet!! I’m sooooo excited watching you grow as a rocketeer and video maker ❤❤❤ (also salmonnnnnn)
🐟 Thank you!!!
Andrew,
Grains of propellant comes from early use of black powder for firearms. Early black powder was produced in mills which resulted in it having a grain like texture, thus the name. Since black powder was the basis for all propellants for a very long time, the terminology was carried over to newer propellants. Also, most black powder in the US comes in sizes classified as F (fine) or C (coarse), and are delineated further by multiples of F or C. For example, most muskets used FFF or FF powder, but most primers used FFFF (or 4 F) as the higher multiples indicate finer powder.
Hi Chloe! Andrew, the Sleep Focus mode coming on just before talking about sleep deprivation was *chefs kiss*. Big fan of accident investigation stuff, the visual representations of your root cause analysis were fantastic. Learned a lot, as always.
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LMAO I didn't notice the timing XD
My first unintentional easter egg 🥚
Awesome analysis! I can't wait to see the design unveiled for Saros!
Possibly the most educational video I've watched so far this year. Kudos and thanks for the new tools; those analyses coupled with setting your ego aside to take a candid look at the causes of faults in a complex system are definitely skills that are broadly applicable outside of rocketry. Well done!
Hi Andrew, nice video. When I watched the motor burn, I immediately thought igniter is in the first grain. One thing that I tell people is to take the igniter and put a bend in the wire at about the length of the motor. That way it helps knowing if the igniter is all the way up to the top of the motor and not hitting an intermediate grain boundary where two grains meet.
On moon burners, C-slot motors, etc with offset cores, I will cut a channel in the nozzle grain end to facilitate proper igniter insertion. Often a wiggle and giggle of the igniter wire will help get it past grain ends if there is any question about the igniter reaching the top of the motor.
Another thing with offset grain cores is to make sure the cores all line up. I've known many people who simply slide in the grains without ensuring the cores line up (the manufacture's usually ask that the grains be glued in place, so they stay lined up. I once had a team ask me for help when they read in the instructions to make sure a rod can be inserted through the cores all the way up the motor. I went to their motel room and could not put the dowel in any farther than the first grain core. I told them they had to take out the grains and line them up as they inserted them into the motor. They said they were glued in place and i told them to find a vendor for a new motor. They told me all the previous motors they've built were all the same center core BATES type grains. I told them that even though I've built thousands of motors in my life I still look at the instruction that comes with the motor because of changes that are sometimes made.
As for the liner melting, the motor liner/case will usually see burn throughs at the grain junctions were the propellant ends start first and expose the liner to the hot gases for the longest period of time. On commercial motors, they are designed in nominal burns to fail at the nozzle as a safety measure in the event of over pressurization. Better to eject the nozzle than have the forward bulkhead fail and pressurized hot gases blow into your recovery section and avionics.
As for old motor cases failing, I've had some motors cases with over 50 flights with no issues including some I've had since the 1990s. I've also had EX cases I've made myself fail the first time when testing propellant, new liner material, etc and that's all part of doing EX.
As for cameras, I'm a huge fan of all electronics getting turned on at the pad before launch. I know countless people that have lost rockets and or their video (including myself) because they had to turn things on before being at the pad or using too small a battery that would not last AT LEAST ONE HOUR, two hours even better. one of the issues I've seen with processors faster than 1080 video is an overheating problem when inside a rocket and out on a pad for any length of time.
Now for checklist. I'm a huge fan of them and am always asking teams (students of others) where their checklist is when out at the pad. It doesn't need to be lengthy and if done properly, could be given to someone not connected with the project to simply read them off as the person or team completes them. I've lost a couple of rockets because I wasn't using a checklist and I've been making rockets now for 63 years.
By the way, I believe the longest motor burn at FAr was approximately 5 minutes. It was an ex motor that they got two of the ingredient amounts backwards.
As a person that has done lots of root cause analysis at a Big Aerospace Company, I LOVE fishbone diagrams! We always started with a huge brainstorm of possible root causes and then organized them into categories. For each possible root cause, we'd assemble supporting and refuting evidence on its own set of ppt slide(s).
It can be an extremely intellectually satisfying exercise, and another big plus is that is FORCES you to slow down and think. When things go wrong we often want to fix it right away, but that's often the worst thing to do, as humans aren't very good at on the fly root cause analysis, and we can easily destroy evidence by acting too quickly.
Well done. That eureka moment in engineering when what you're seeing and sensing and feeling all aligns with the math and physics, that's the best. Keeps you coming back for the next puzzle and the next.
This is a great explanation and example of an anomaly investigation, and very well edited as well!
Also that was an adorable dog (and salmon)
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I'm not saying the "B" in Joe B stands for "Blame", but lets just put it out there and see if it ignites...
That said, sleep has been a major factor in many of my issues but darn, that last-minute buzz is so addictive.
I really liked the ishikawa diagram, I had not seen one before however It did remind me of the swiss cheese model but with a different goal in mind.
Great video, the length was perfect and I can't wait for the eclipse rocket. Good luck.
Great video, very well laid out and appreciate the explanation part. Good luck going forward.
Fantastic and brutally honest analysis of this failure.
Love this analytic video style, awesome work
Great video! Loving the episodes so far!
I learn so much from your videos. Really appreciate the effort you put into them.
This was really well done and I learned quite a bit! I thought your video style was engaging and your methodology thorough- looking forward to hearing and seeing more about this project!
absolutely loving all the detailed explanations Andrew! You, Xyla and Joe are awesome engineers and better people!
One of the hardest things we can do is criticize ourselves honestly to assess where and how we failed to prepare ourselves for the next time so we can succeed. This was a humbling experience I'm sure, but it is better to have these failures now, and learn from them, than to fail the cosmic launch over something simple like wrong parts or lack of sleep. I can't wait for you videos of the eclipse, YOU GOT THIS!
Also, won't the camera need some form of tint to protect the sensor from the direct sunlight? Or is that just for sustained durations and high magnification lenses?
Really enjoyed this, especially your willingness to admit fault. I appreciate your detailed analysis.
Also, Joe cameo is always fun.
masterclass in fault trees, thank you
Excellent Video!
Great video! Turns out that people's mistakes are other people learning opportunities.
Thanks for another great video woth gteat detail, I really hope it will launch sucsessfull the next time. Thanks for all the deep details we get and you give me much inspiration how ro built my modelrockets (Im planing one with liqiud nitrogene and water propulsion at the moment) and making them more stable and sucsessfull. Thanks for making the video
Amazing intro
Hey, very interesting and educational video.
A slight comment on the video editing.
In your videos, you have a lot of information, with written information that stay on screen for like half a second with different spoken information at the same time. It gets very hard for me to take in everything at the same time.
I've had to pause and go back (sometimes several times in a row) numerous time during this video, and it makes watching it difficult.
For example, when you're commenting on the footage, you have text that appears on video while you're talking and exactly at the same time something happens on the footage for half a second. Each event required me to go back, because I could never catch it on the video. It would have helped if the text appeared like 2s before, and maybe if you slowed down or paused the video at the even, highlighting the region where we should look at.
I know it's a lot more work during the editing, but it would make your video tremendously more accessible, especially for non native speakers like me, for whom it takes slightly more time to read and process what you're saying/writing.
But again, I loved watching, I learned a lot, and I look forward for the next parts of the project.
It'd also be very interesting if you make more videos about the design process and not just the launches :D .
20:00 so what I’m hearing is that it’s joe’s fault 🙃
I liked the last joke😂😂
29:54, time for bed! 🤣
On "Grains". Do not take this as the gospel but I suspect the usage relates to the fact that black powder and smokeless powder for use in firearms are measured in Grains. As the development of rocketry has common roots with propellant I think that might be the origin. Interestingly in shooting grains are used as a unit of measure of the "grain" still.
I'm thinking that the moon-burner needs to be shaped near the nozzle end so that it's a shaped transition from center burner (at the nozzle) to moon burner (slightly further up) so that there's no "corner" that the igniter has to pass through, just a smooth passage, and you'll be able to get the iginter up to the front end easily. Is it possible to make that section of the propellant have a shape life that?
You totally can! These motors are pretty easy to disassemble and you can definitely scrape a little bit of propellant off by hand with a hobby knife or drill bit if you're careful. Definitely will check for next time :)
Some motor makers of moon burners make the aft nozzle grain core shape like that. Not sure if CTI does but as Andrew says, the propellant is easy to cut a channel for the igniter to be put through. Not sure if this motor had a grain like that but is possible if it did that it was placed upside down or not at the nozzle.
That's a lot to say "Joe was a bad influence."
"Salmon"
Salmon
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Hi Chloe!
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TL;DR
To sum it all up in a few words - if you've bought this motor, never do it again from this seller (I doubt that you've made this motor by yourself).
Of course one can analyze all what was going on around this launch, but... If the motor is sucks - nothing helps.
salmon
Hi Chloe
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I love the content, the text you display on the screen is too fast.
You should try to leave text displayed long enough to slowly read the text, but that is only part of the problem.
There is a brain issue that public speakers have been aware of for years but is not well spoken of. The same part of the brain which is used for listening is also the same part used when reading. This isn't an issue when the content is the same, when it is sudden, different, and simultaneous with another input, both loose clarity.
Instead of attempting to use tiny text which is going to be smaller on a smaller screen, simply just pause and add a voice over for important information. Better yet rather than doing aside comments address the issue at the appropriate point of your story...when you discover it. The aside comments don't add to the smooth flow of the story.
Salmon
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Hi Chloe!
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Hi Chloe!
🐶
Salmon
Salmon
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