Ultimate Endeavor Modification- anybody tried?

Anybody tried to convert a rocket from a 54mm motor mount to a 76mm after the rocket is built?
I built my PML Ultimate Endeavor intending to use it for my Level 2 last year but ended up using a smaller rocket with a J350 based on motor availability. Now I am mostly just flying sugar motors (a lot cheaper for certain!) but my AMW 54mm casing will only get me up to a full "J" motor with sugar. I am building some 76mm hardware and would like to reconfigure the rocket to a 76mm mount. The endeavor has two sets of fins at the bottom and they are quite large. Looks like a lot of tricky dremel work to me! Not too mention the 3 half inch thick centering rings already installed.
Anybody do this kind of operation before? Any tips? Should I bother?
Thanks,
Stuart Leslie

I haven't tried it but, I've thought about it on occasion. As I see it, the difficulty would be getting the new motor mount attached squarely & rigidly to the rest of the airframe. I was thinking about something like a drillbit the size of the od of your new motor mount that has maybe 2 or 3 inches turned down to 38mm.
If you come up with a good way to do it, I'd like to know.
Phil Stein
On Fri, 25 Jul 2003 20:51:42 -0700, "Stuart Leslie"
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Phil Stein

Why not a longer custom 54MM motor case? It would probably be cheaper and easier in the long run to just build a new 75MM-capable rocket.
J.A. Michel
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You could easily build another bottom half for about $140.00.
get the phenolic tubing (MMT and Body) & centering rings from Red Arrow. Order U. Endeavour fins from PML... Make sure they cut em for 75mm fin tab and not 54.
Or rip the fins out cut em down to 75mm fin tab and just get new tubes and CR's for $55.
Slot and cut your own tube.
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Thanks for a bunch of great suggestions, my strange rocket logic goes like this: I have this spankling clean, beautiful two tone paint job with future finish on the rocket now that I spent a lot of time sanding/painting to achieve. I don't think I could "rip the fins out" without great emotional stress! Same goes for making a new bottom section as this is where most of the work went. I do like the suggestion to go for the 98mm while I am at it though, never know where future motors will go to! As to lengthening the 54mm with custom hardware, This still does not let me get very far into the "K" range without erosive burning concerns. The wider diameter motor also lets me get longer burn times (2.5 seconds is long in the world of sugar motors!)
This leaves me with the challenge of having to cut out 3 centering rings, cut out 54mm mmt and three 38mm motor mounts, as well as trim about 1/2 inch off each of 6 fins. Trimming the fins is the part I can't really figure out. A hack job would likely result in fins that don't bond to well to the new motor mount. Can't fit a dremel into the long tube to reach the fins so I don't know how I will trim them. Also will have to figure out how to fit the center centering ring in without compromising the ability to apply the internal fillets on all the fins.
I know it is crazy but somehow spending hours retrofitting my existing rocket "makes more sense" than just starting with a new rocket. I will fire up the dremel today and just dive in I guess. My initial plan is to fasten a steel straight edge to each internal fin tab, then drum sand the tabs to the straight edge at the correct depth. Wish I could fit the dremel in to use the cutoff wheel but I don't think that is going to work. The middle centering ring will likely have to be cut into thirds and inserted once the fins are nicely secured to the motor mount.
I will take pictures and post the results on my web page (http://home.mindspring.com/~sleslie/index.html ) if anyone is interested.
Thanks again for the suggestions.
Stuart Leslie
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Someone said about getitng the MMT alined. Fit a CR at one end. Smeaer epoxy where it will stick in the bt say above the fins. Feed this down from the the front of the body and then smear epoxy n the other inside part of the bt and MMT and fit one more cr. Then do the tape thing that pml does and jsut slide one more cr on. leave to set and in theroy it might work. i guese ou could foam the can by drilling some holes and pooring it in and then a bit of 5 min epoxy when it's in the gels stage to fill the hole.
I know not great woridng but you might get the idea.

Wow! That's a great idea! I was just about to start dremeling when I saw your post. This looks like the best way to go so I will give it a shot.
Thanks,
Stuart Leslie ------------------------------------------------------
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Hey Stuart, report back and let us know how it works out.
J.A. Michel
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me!