So,

OCD can be a bad thing. I wanted to put the Center of Pressure decal and the Center of Gravity decal in the correct locations. I found both a D12-7 and a C11-5 for use in the CG measurement

Using the Bruce Lee worksheets Dave posted in another thread, I calculated the CP of my Semroc Cherokee-D as 17.18" from the tip of the nose. With a D12-7, the CG is only .875" ahead of that and with the C11-5, 1.625" ahead.

The Semroc kit is short body (16.35") like the original and I added a hardwood dowel to the nose cone to give the screw eye something to bite into. Still need a bit more nose weight.

If anybody wants to check my math, great. I'd note that using an 18" body tube moves the CP slightly forward (1.46") but this is offset by the CG having a longer moment arm.



Addendum: For fun, I measured the CG on the old Estes Cherokee I mentioned above with the same D12-7 and I don't know if the paint is heavier or the balsa cone denser, but its CG is 1.375" ahead of the CP. So it's OK.

__________________
NAR 79743
NARTrek Silver
I miss being SAM 062

Awaiting First Launch: Too numerous to count
Finishing: Zooch Saturn V; Alway/Nau BioArcas; Estes Expedition; TLP Standard
Repair/Rescue: Cherokee-D (2); Centuri Nike-Smoke; MX-774
On the Bench: 2650;
Dream Stage: 1/39.37 R-7