L3 cert project, coupler length - Northern Colorado Rocketry

This topic has 4 replies, 3 voices, and was last updated 11 years, 10 months ago by LWade.

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November 12, 2013 at 7:33 pm #41694
LWade
Hello,

I am designing a 7.5″ (PR G12) fiberglass rocket for my level 3 certification and had questions regarding the length of the couplers. I have read about L3 rockets failing in the coupler area and have seen recommendations of up to 2X the caliber of the rocket. How much overlap should there be? I am designing the rocket to use motors up to M3000 (75mm).

Thanks for you help!

Lwade
November 14, 2013 at 3:33 am #56662
Christopher Dreher
Most people put at least 1 caliber of coupler sticking into each end the body tube, so for a 7.5″ diameter rocket that would be a coupler with a total length of 15″. The PR fiberglass tubing is very strong and 15″ would be adequate IMO. Definitely run your ideas past your L3CC/TAP though.
November 15, 2013 at 4:54 am #56663
LWade
cdreher

Thanks for the information. I’m a Tripoli member so I will run my ideas past a TAP member at the next launch. Thanks again!
November 20, 2013 at 7:03 am #56664
James Russell
have you contacted a TAP yet? Mark L, Art H and myself are the most active of TAPs here but there still are a couple of others in the area. feel free to shot me an email at jamesr2 at gmail and I can make sure that you have our info for questions and review.
November 20, 2013 at 7:23 pm #56665
LWade
James,

Thanks for responding, I just asked Joe H who the TAPs were the other day. I will send you an email soon, will you be at the December launch?

I have many other questions, but will create a separate post.

Thanks,
Lwade
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