Location of forward rail button.

[RonboDismo]

Howdy,

I'm building the Mach1 Desdemona. The issue I'm running into is I can load an H motor and up to a J motor. An H motor gives me a CG of ≈ 11" and a J motor is ≈ 7.5" according to RockSim. Any suggestions on where I should locate the forward rail button to cover these situations? Thanks in advance.

 

[dhbarr]

Somewhere convenient between the farthest north CG and the CP should be fine, assuming you're doing exactly two.

 

[RonboDismo]

Correction: H motor CG ≈ 9.8". So somewhere between 7.5" and 9.8". Or does it matter as long as I'm somewhere in-between?

 

[RonboDismo]

Somewhere convenient between the farthest north CG and the CP should be fine, assuming you're doing exactly two.

Excellent, thanks.

 

[dhbarr]

Excellent, thanks.

Yeah, 8-9" should be just fine.

 

[tim cubbedge]

I usually put my FWD rail button somewhere around the CG with no motor.

 

[RonboDismo]

Thanks all for the excellent advice.

Original post was a total brain f*rt. The CG for H motor is actually 42.65" and 44.553" for J motor. Because I only have the aft portion of the rocket, what I did was a ratio conversion from measuring the distance from the forward edge of one fin on my screen in RockSim and then converted to actual rocket, and that's how I ended up with 7.5" and 9.8" from the forward edge of a fin. Doh. :-(