Little John 4” CP

[IndianaSteve]

Looking for a little help here. I’m building a MadCow little John4” paper rocket for my L1 attempt. I’m wondering if anyone with Rocksim or Openrocket could find out the CP for me. I did the cardboard trick and want to see how close it is to correct. I know I will need nose weight and want to get as close as I can for my L1 flight. 
My laptop is down, and neither program is mobile friendly 
Appreciate any help

[MarkH]

What are the major dimensions, such as body tube length and diameter, exposed nose cone length and fin dimensions? I will try to draw it Openrocket. Should be good enough for an approximation anyway.

[IndianaSteve]

I would appreciate that very much Mark!

4” diameter body tube that is 31” long
Fins are,
Root edge 8”
Leading edge 6 1/2”
Trailing edge 3 1/2”
Connecting edge 1 1/2”

1/4” exposed of the body tube under the fins.

Nose cone is 16 1/2” exposed.

[MarkH]

I would appreciate that very much Mark!

4” diameter body tube that is 31” long
Fins are,
Root edge 8”
Leading edge 6 1/2”
Trailing edge 3 1/2”
Connecting edge 1 1/2”

1/4” exposed of the body tube under the fins.

Nose cone is 16 1/2” exposed.

Here you go. First image is one I drew in Openrocket. Second one is from Madcow site, after finding the Rocsim file on their site. Madcow version has the fins all the way aft. CP is pretty close to 35" either way.

[IndianaSteve]

Awesome thanks Mark! I was getting a pinch over 34” from the cardboard trick so I’ll just split the difference and go 34 1/2”.
I appreciate the help!