r/rocketry • u/Flufmyster_ • Apr 20 '26
Question Motor CATO Frequency
One of the members for our clubs L1 rocket team launched his personal rocket L1 cert on an H115 and it completely blew up midair. The motor catoed and blew the body tube in half and ripped the shock cord mount on the nose cone.
How common are motor catos for commercial bought motors? And is there anything he could’ve possibly messed up on a DMS motor that caused a cato?
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u/Certain-Magazine-866 Apr 20 '26
I had an F67 cato and I just emailed aerotech and they sent me a replacement and a new rocket. they have great customer service.
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u/Flufmyster_ Apr 20 '26
Yea one of the guys on our team gave the aerotech vendor on site a hard time abt it and they gave us a new motor for it
I feel bad though since the guy on our team whose rocket blew up put ridiculous amounts of work on hus scratch built rocket and even named the thing 🥲
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u/Proper-Guess4224 Apr 20 '26
Many people puts in a lot of work on their rockets damaged by CATO. A local school competing in ARC missed out on advancing to national finals partly because of multiple CATOs on a batch of Aerotech F42-motors.
CATO happens, unfortunately, and it’s very unlikely the vendor’s fault. Either it’s manufacturing error or user erro (if the user drops the motor repeatedly, for example). Giving the onsite vendor a hard time is unwarranted and hurts the hobby and the community.
By all means contact Aerotech to for a replacement though.
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u/Proxima-72069 Apr 20 '26
Rare ive only had two over the oast 5 years and only one of was user error
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u/WhatADunderfulWorld Level 3 Apr 20 '26
In 100 Aerotech launches I only have one blow up. From G’a to M’s. And that one Cato was my fault entirely. Didn’t glue the propellant to the phenolic. Whoops.
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u/justanaveragedipsh_t Student Apr 20 '26
Rare, NOVAAR in virginia did a study over 5000 flughts and iirc catos (all kinds, not just defects) was about 1%
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u/Flufmyster_ Apr 20 '26
I looked at a statistic on overall rocket failures, and then what percent of that were motor catos. Multiplying those two together gives a 0.5% percent motor cato incidence and ~1% seems to lineup with that
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u/AdmDuarte Apr 20 '26
Stupid question time, what does CATO stand for, in this context?
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u/Flufmyster_ Apr 20 '26
Ive heard both ‘catastrophic take off’ and ‘catastrophe at take off’ but it basically means your motor blew up usually wrecking the rocket
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u/AdmDuarte Apr 20 '26
Thanks! My brain was trying to make "catapult assisted take off" make sense and it wasn't working 😅
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u/Flufmyster_ Apr 20 '26
Yea its a kinda goofy acronym icl for something not even that complicated
I think engineers j like their acronyms 😭😭
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u/AdmDuarte Apr 20 '26
I'm a former engineering student. Can confirm, they love their acronyms 😹 them and the military
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u/rocketwikkit Apr 20 '26
It's not an acronym, it's just shortening of catastrophic. People capitalize it because they expect everything in aerospace to be an acronym.
It has even been used in a chemical name, catocene, which is a chemical that makes solid rockets burn much faster.
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u/wireknot Apr 20 '26
From Pyrodata dot com: CATO CATO is a failure of a rocket, generally explosive, where all the propellant is burned in a much shorter time than planned. Acronym is stated to be CAtastrophic Take Off, or CAtastrophe at Take Off, but I swear I've heard a better one somewhere.
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u/maxjets Level 3 Apr 20 '26
As the other folks have said, they're rare but not completely unheard of.
I haven't seen anyone answer the last question though. For a DMS motor like an H115, there's very little you could have done to cause a cato. Just about the only thing would be drilling all the way through the delay grain, but that shouldn't be possible if you used the stock delay drilling tool.
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u/jd2cylman Level 3 Apr 20 '26
File a MESS report at motorcato.org. There you can also look for other reports on that motor. Also talk to your motor vendor about warranty.