CTI 75mm grain spacer O-rings

[tim cubbedge]

Assembling my first 75mm CTI reload, an M1101. It's a 4 grain. Question - each grain comes with an O-ring so do I only place the O-ring in between each grain and end up with an extra O-ring or does the 4th O-ring go on top of last grain in between grain & forward insulator disk?

I do not see the last O-ring in the supplied drawing so I just want to make sure it's done correct!

 

[Steve Shannon]

See post #3 in this other thread: https://www.rocketryforum.com/showthread.php?134545-CTI-75mm-O-ring


[emoji1010] Steve Shannon [emoji1010]

 

[tim cubbedge]

Thanks! There is room for it so I will use it!

 

[jimzcatz]

Don't need it, but not gonna hurt either.

 

[watermelonman]

I think I am on my seventh Pro75 motor and the last O ring has fit every single time. I am curious how much variation there is in grain and liner length, what the production tolerances are.

 

[tim cubbedge]

I had room for it so I used it. Without it, the grains floated. With it, everything is snug. Production date Jan 27, 2016.

 

[watermelonman]

Good luck with that certification flight. Here was my M1101 flight -