Interesting how this suggests filling the vacuform fins with foam prior to gluing on, even going so far as to suggest Home Depot's "Good Stuff" canned foam. I had thought about using "Good Stuff" on the fairings as well, possibly injecting foam after gluing them on...
Why would you want to do that?
Plastic wraps are primarily decorative, and secondarily add a bit of structural reinforcement. The best thing about them is how light they are, and adding any additional weight would only make the aft end of the (already porky) rocket that much heavier, requiring more ballast in the nose (making it heavier yet).
I would advise against that.
Keep it light, keep it simple.
But having been warned:
But now I'm wondering if this warning has to do with injecting the foam after gluing the fairings on (which on curing could put too much pressure on the fairings) as opposed to filling the fairings with the foam, letting it cure then cutting the excess away and slicing out slots for the fins... this stuff is incredibly light... of course I suppose the canned stuff could attack the plastic...
Yes, but why?
If you are worried about braking the plastic fins - they will break either at the point of attachment to the body tube, or chip off the exposed upper ends. Either way, you want to be in position to replace them as easily as possible (replacement fins are readily available from Estes), and filling the fairing would only make the replacement job harder.
Once you glue the fairing to the airframe and the edges of protruding fins, they become fairly firm. The only reinforcement I added to mine is gluing the semi-circular card-stocks to the aft end of the fairings, and that was mostly to hide the imperfect fit, similar to this:
https://modelrocketbuilding.blogspot.com/2011/05/estes-saturn-v-build-part-33-glue.html
Also, how far from the tip of the nose should the CG for this thing be? Anyone?
Please see my OR model below - 20.3" from nose tip, as pictured below.
Note that my tail is heavier than normal, due to 29mm motor mount upgrade, and 5mm plywood centering rings.
That is without motors, but with stock 29g ballast in the nose.
I would need 58g to get 1 caliber of stability with E30 motor. More for longer/heavier motors.
You really want to maintain and adjust your own .rkt file to model stability for your build weight and chosen motors.
HTH,
a