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-   -   "D" conversion and plastic/balsa NC question (http://www.oldrocketforum.com/showthread.php?t=149)

six-o-one 05-06-2005 03:20 PM

"D" conversion and plastic/balsa NC question
 
Couple minor questions if anyone has any input for me. First, upon retrieval and repair of the tree'ed Cherokee D, I replaced the balsa NC with the plastic version (as the balsa one is still in the tree). Will this create a stibility issue? There is no notation in the plans for the original plastic NC version about addition of weight. Just doing an approximate CG/CP it seems OK, but there has to be a weight distribution difference. Oh well, any thoughts on the subject are appreciated.
Secondly. Finishing up my Estes Vigilante 2-stage clone. Used a CC-Express for both stage BTs, with just a minor cutting down of the booster to correct size. The Vigilante is a C-toC motor setup. The CC Expresss came with D motor mounts. Wondering if I could make me a D motor booster just like the one I have, so I could use both. Would the additional thrust overpower the 3/32 fin stock, or would it be OK as long as I still have a good CG/CP relationship?
Thanks for any input.

CPMcGraw 05-06-2005 05:07 PM

Quote:
Originally Posted by six-o-one
Couple minor questions if anyone has any input for me. First, upon retrieval and repair of the tree'ed Cherokee D, I replaced the balsa NC with the plastic version (as the balsa one is still in the tree). Will this create a stibility issue? There is no notation in the plans for the original plastic NC version about addition of weight. Just doing an approximate CG/CP it seems OK, but there has to be a weight distribution difference. Oh well, any thoughts on the subject are appreciated.
Secondly. Finishing up my Estes Vigilante 2-stage clone. Used a CC-Express for both stage BTs, with just a minor cutting down of the booster to correct size. The Vigilante is a C-toC motor setup. The CC Expresss came with D motor mounts. Wondering if I could make me a D motor booster just like the one I have, so I could use both. Would the additional thrust overpower the 3/32 fin stock, or would it be OK as long as I still have a good CG/CP relationship?
Thanks for any input.


I have cloned the short-body Cherokee-D with the plastic NC, and it flies great. :) Keep in mind, Estes' designs have traditionally been over-stable to compensate for not-so-accurate building skills. ;) The slight weight difference shouldn't change the CG enough to de-stabilize the model.

When Estes released the #1247 version of the Cherokee-D, they lengthened the body tube to a full 18" BT-55. This obviously helped make the rocket even more stable, but I think it was more of a simplification of the parts list than a concern for stability. :rolleyes:

You should be fine with the D mount from the C-C Express booster. I would suggest venting the booster, and taking a little extra care when attaching the fins, but beyond that you should be fine. If you're in doubt, go look at the #1955 Ranger. This is a "D" bird that uses the Vigilante's fin sheet. :D


Craig McGraw

six-o-one 05-09-2005 10:47 AM

Craig,
Well, that covers me. I appreciate the time and info. Wondered about what I had heard about the lengthened Cherokee D version, so that clears that up. Thanks again.

Rob


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