question on AT G75J RMS

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tomsteve

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I have a couple of these( for the 29/180 case) and am planning a launch this weekend. went ahead today and packed the motor today. seems the motor "rattles" a little inside the case after assembly- when I shake it lightly- fore to aft direction- seems theres a bit of play in there. I went through the instructions very carefully a couple times to see if there was something I missed and even repacked the motor 3 times just to make sure. so now im wondering if im missing something here or if this is how the motor is when packed.
any insight would be greatly appreciated!
 
I think you are good to go. Many AT motors 'rattle' a bit. If you packed it as per the instructions, I say 'Let 'er Eat!' BTW, I have flown many of them,nice motor! Tim Thomas L3
 
I had the same question when I put my first AT motor together. I'm a CTI flyer, and they just don't rattle.

In the instructions, refer to step 2.9, figure 11 "It is normal if the grains rattle slightly inside the linerafter tightening."

https://www.aerotech-rocketry.com/c...MS_Instructions/29mm/29_180-240j_in_20045.pdf


welp, I did miss something!! I didn't COMPLETELY read 2.9. I got through the resistance in threading thing, then moved on. DOH!!!

thanks all!!! hopin the weathers good for flying Saturday! I have a yank enterprises Hawk ive had for 16 years. its maiden flight was in the spring( of this year!) on a G76 and im thinking the G75 should make for a pretty awesome flight.
or
pack it in my estes nike????
dammit, I just gave myself a choice!!!!:y:
 
I have one of these motors just waiting for the perfect day to fly it. Post pics!
 
I think most motors that rattle are because of the manufacturer being too cheap to provide O rings, and hoping that the motor will come up to pressure in such a way that causes the grains to float in relation to each other.

Another solution is to curve one face of each grain. Cesaroni 54mm is like that, and I have had good luck with that on small EX motors.
 
I think most motors that rattle are because of the manufacturer being too cheap to provide O rings, and hoping that the motor will come up to pressure in such a way that causes the grains to float in relation to each other.

Another solution is to curve one face of each grain. Cesaroni 54mm is like that, and I have had good luck with that on small EX motors.

Grain facing like that takes more time, which would raise the labor costs, raising our cost. In 54mm motors, I don't think oring spacers would be wise. They have to pass through the nozzle if they don't get consumed, plus the performance gain is not worth the effort.
 
You mean...when I fly a J510 that popping sound isn't breaking the sound barrier 5 times?

It is likely the grain liners being ejected as they burn up.

I have not flown the J510, but have flown a bunch of J570. The popping is very predictable. I should look at a Thrustcurve of it and see if the pops show up there.
 
It is likely the grain liners being ejected as they burn up.

I have not flown the J510, but have flown a bunch of J570. The popping is very predictable. I should look at a Thrustcurve of it and see if the pops show up there.

yep. Was a sly joke about every time I fly one someone goes "did you just hear it break the sound barrier? Wow " when it was just puking casting tubes
 
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