Warning, another batch of G-12 motors may have serious issues 05161910!!!

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burkefj

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I flew my upscale orbital transport glider today, all motors from batch 05161910
I've had trouble in the last 10 years in maybe 30 flights with four other anomolies, in all four cases the propellent burned 3x faster than normal, in one case the model survived as did the casing, in three other cases the case split like a banana peel and destroyed the model. George Gassaway and I believe it is a propellent void causing an overpressure, I was very careful to fully grease the forward end of the propellent and liner so don't think it was burning on both ends. In this one case I did not find the closure but did recover the 0 ring and the split open casing. I personally won't fly G-12's any more I have lost 3 models in maybe 30 flights unfortunately, they have discontinued the casing but still make the reloads, but I will just go for the new H-13 29mm longburn motors from now on....I did get three flights on video as well as the explosion...

Here are three other threads where I've had similar issues
https://www.rocketryforum.com/threads/two-motor-failures-yesterday.49350/#post-482119
https://www.rocketryforum.com/threads/problem-with-g-12-batch-05021702.149855/
https://www.rocketryforum.com/threads/big-yf-12-rc-rocket-glider-for-g-12-motors.157793/post-2055838



and one of my SR-71 flights with fast burn:



and one of the Bomarc where the same thing happened...



IMG_20201019_140026281.jpgIMG_20201019_140104181.jpgIMG_20201019_140109360.jpg
 
Last edited:
Frank, thanks for the update. This does not sound good for me. I have two G12 2-paks with the same lot number 05021702 that you are talking about. I also have an AT single use G40 with lot number 03620.

I see that the G40 failure dates back to the year 2013. I bought this motor a few weeks ago. I am planning to use it in the Viper.
 
It's luck of the draw, you may or may not have trouble with them, if you chose to use them don't be surprised if you have an issue, and can decide if it's worth it to you to have to rebuild something.

Frank, thanks for the update. This does not sound good for me. I have two G12 2-paks with the same lot number 05021702 that you are talking about. I also have an AT single use G40 with lot number 03620.

I see that the G40 failure dates back to the year 2013. I bought this motor a few weeks ago. I am planning to use it in the Viper.
 
Looking at the top of the thread right now I see that I have a different lot 05021702. I have two G12 2-paks. I just weighed 3 of the re-loads and the propellant and liner for all of them weighs 61 grams. The package lists the propellant weight as 51.1 grams. Does the liner weigh 10 grams? I assembled one of the re-loads to find the c.g. in my SST model. That assembled weight is 129 grams, which is close to the listed 126 grams assembled weight on the package.
 
My propellant with liner also weighed 61 g for the first two. When I got to the field decided I'd fly two more and didn't have the scale with me so I don't know if there was a void or not on the one that failed or if there's some other problem causing the propellant to burn faster than normal all of a sudden.

Looking at the top of the thread right now I see that I have a different lot 05021702. I have two G12 2-paks. I just weighed 3 of the re-loads and the propellant and liner for all of them weighs 61 grams. The package lists the propellant weight as 51.1 grams. Does the liner weigh 10 grams? I assembled one of the re-loads to find the c.g. in my SST model. That assembled weight is 129 grams, which is close to the listed 126 grams assembled weight on the package.
 
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