Foam board centering rings

[les]

Anyone have experience using foam board for centering rings on the motor mount for LPR? Is there any issues with the motor heat melting the foam core?

Thanks

 

[Stan]

I have been using foam board for my CRs in larger diameter mods of Big Daddys, maxi alpha IIIs, where I extend the mmt to reduce need for tons of wadding. The thickness of the foam gives more surface area to build rigidity.

 

[dk54321]

I've been using foamcore for centering rings. Works great. I've used it in rockets up to E power so far with no melting issues. One problem I did have was cutting a perfectly round hole exactly the right size with sides perpendicular to the surface all the way through. Solution: cut the hole slightly under size, then wrap some course sandpaper around an engine casing one size smaller than the intended engine mount. Sand the hole to the proper size and shape, checking frequently with your motor mount tube for the proper fit. Similarly, to get the O.D. perfectly round and the proper size, cut it slightly oversize, then tape some course sandpaper to the inside of a body tube the next size up. Sand and test fit repeatedly until you get a good fit. BTW, I recommend wood glue for the bonds between CR and MMT and CR and BT.

 

[cruzsergio]

This big guy below is 7ft tall it uses 3 E 9-4's to get lifted off. it few once on E12's.
The rocket is a school project three years old.
It also uses foamboard(poster) board as centering rings.
In my case by the third flight the foam had melted, lifting the paper.
we sloved that by adding a nice thick coat of glue to give it more durability and it's strength.
No problems ever since.
Below was it's last recent flight last year on July 14 2012

 

[rocketguy101]

This rocket flys on "F" motors and has 1/4" foam core CRs...it has flown several times with no problems. I did coat the upper ring and lower ring with glue for protection (as mentioned above).

 

[cwbullet]

I have used fiberglassed foamboard up to a J.

 

[rstaff3]

I've used it successfully on 29mm G/H models. On the top ring where it might encounter ejection gasses, I schmeer some carpenters glue on the ring.

 

[dcbertelsen]

1/16 scale V-2 out of cardstock with foamcore CRs. Art Applewhite has many rockets that use it as well.

For cutting, I use one of the hobbyshop circle cutters. Multiple passes and a sharp blade work well. You just have to be careful to avoid enlarging the center point hole.

 

[GuyNoir]

I've used it in virtually all my paper rockets, regular size and enlarged, with no problems.

 

[TheAviator]

I've used it mostly in contest rockets. For small BP motors, just leaving the paper is enough to protect from the ejection. Larger motors might benefit from a coat of glue or oil based polyurethane.

Also, it cuts very well on a laser cutter if you can get at one.

 

[les]

No laser cutter available - just an exacto knife.
Will be using foam rings on two odd roc designs I'm working on

 

[rocketguy101]

nice article by TimV in the Apogee newsletter
https://www.apogeerockets.com/education/downloads/Newsletter126.pdf