OK. Here is what I did. Open the Example Tube Fin Rocket.
[ Shows apogee at 1175ft with the D12-7 in the example file.]
1) Open the "fin set" and un-check the automatic calculations.
2) Set OD to .976in and leave ID at .95 & Wall at .013
3) Change Number of fins to 3
---- Apogee changes to 784ft.
---- In the plot of Drag vs Mach. CD=2.3 @ Mach.25
4) Change Number of fins to 4
---- Apogee changes to 876ft.
---- In the plot of Drag vs Mach. CD=1.9 @ Mach.25
5) Change Number of fins to 5
---- Apogee changes to 999ft.
---- In the plot of Drag vs Mach. CD=1.55 @ Mach.25
6) Change Number of fins back to 6
---- Apogee changes back to original 1175ft.
---- In the plot of Drag vs Mach. CD=1.12 @ Mach.25
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2nd issue
If I wanted to show 3 fins as red and 3 as black in the image. I made 2 sets of 3 fins. (File attached.) The design file looks exactly like the original and should be the same simulation. (ie 1175ft.)
BUT
---- Apogee drops to 573ft
---- In the Plot of Drag vs Mach. CD=4.0 @ almost Mach.25
Any Ideas..... ?