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REAPER

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Hey Y'all

It's great having TRF back,thanks to everyone involved for bringing back a great forum.
I need a little help finishing my Polecat 5.5 Nike-Smoke,I'm trying to finish it in time for our (SSS) club launch on Feb 14.
My 1st question; does anyone know what the correct CP is for this rocket??
I looked it up in EMRR and got 2 measurements--55" & 60" from the tip of the NC. The instructions with the rocket clearly state:"The CG should be 55" back from the tip of the NC." I'm confused ???????? Any help would be greatly appreciated.
My 2nd question; would KILZ be OK to fill the fine weave on this rocket. While TRF was down I read about someone doing this on ROL,and I thought this would make it much easier to finish. Any thoughts??????

Thanks for any help.
 
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powderburner

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I can't help you with the CP/CG on that kit, but I can offer these comments about Kilz.

Kilz (either the oil-based or the water-based version) is a sealant product designed to cover stains, other paints, etc, and stop any discoloration from beneath from bleeding through to stain whatever color you paint on top of the Kilz. It worked great for this when I used it on fire-damaged kitchen cabinets.

It is ** N O T ** the same thing as a true primer for other paints.

Its strong suit is to seal and block stains from coming through. It just so happens to have a lot of 'filler' material, which is what a lot of us like about it for using on rockets. It also gives you a nice white base coat. But it is not especially designed to form a strong physical bond to layers beneath (or above), and some guys on TRF1 had posted bad results with top color coats peeling off of Kilz. (Ask Micromeister, I think he had some bad experiences.)

There are other paint primer products out there that are loaded with good filler materials, such as some of the gray automotive primers. Many of these primers have petroleum products or other oils in their formulations, and I would be a little concerned about oils soaking through rocket airframe materials and doing hidden damage. OTOH, this might not pose any problem at all, especially if you let the primer air out and dry thoroughly. But if you need something that adheres well to the rocket, has lots of filler, and gives you a nice uniform base color, then I would recommend sticking with a product that specifically says 'primer' on the label.
 

REAPER

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POWDERBURNER

Thanks for the input. I generally used auto primer on all of my projects,so I know what you mean. I have used KILZ on a couple of MPR's with good success.provided I let it completely dry. I just thought KILZ would be abit faster to fill the weave.

Thanks Again.
 

MarkM

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1) Kilz: I've used Kilz many times before with good results. After applying the Kilz, I let it dry TWO days to let all the vapors diffuse out, then sand. This will fill the weave nicely. Maybe a second coat will be required which again I let dry two days. I then coat with a layer of true primer followed by sanding. Then color coats. Works for me.

2) I can't comment on the exact CP on this rocket, but can comment on the wording in Polecat's documentation since I've built the Thumper Jr. The instructions state the position of the CG. And yes, it is CG! That means that the CG (balance point) must be at least that far forward with the motor and recovery system loaded. If the CG with the motor is at that position, then the CP/CG relationship will be at least the required one caliber and rocket will be good to go. Hope that clarifies it.
 

REAPER

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Thanks Mark

Thanks for the additional info on KILZ,I think that is the way I want to go. I was going to try SuperFil but the stuff is not exactly easy to work with.
I agree with you on the info in the instructions,its seems Andy would know the best about his own kit's. (I bought it before Jack G. took over.) I think you can see the confusion though,EMRR said it was 60" or 55" and one of those was thru Rocksim.
 

RangerStl

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I find that Kilz works pretty well until you bounce the rocket off concrete. It tends to chip and fine.
 

REAPER

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RangerStl

LOL,I'll do my best to keep it off the concrete. Luckily,we launch in Rainbow Valley which is usually a little softer than concrete this time of year.
 
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