OpenRocket motor weight and reloadable cases

[Bob Scott]

I'm using OpenRocket to model a kit with a Cesaroni Pro-38 reloadable case. Does anyone know if OpenRocket includes the weight of the case and any spacers required when a motor is selected? I'm guessing not, but I haven't seen any .ork files with cases in them...

 

[Peter Olivola]

OR uses the assembled weight of reloads. If you need spacers external to the motor, you have to include them in your design.

 

[Sampo]

Hi,

The data is based on thrust curves from thrustcurve.org, which should contain the standard casing weights. However the data file formats have the limitation the mass of the casing and propellant is the same regardless of the motor delay.

Still, the uncertainty in atmospheric conditions, motor variations and simulation precision probably cause a much larger error than a few grams for a missing spacer.

Cheers,
Sampo N.

 

[Rocketjunkie]

The motor weights are the total weight of the motor with the case size for the reload and propellant weight. If you are using a longer case and spacers, you will need to add a mass object for the extra weight of the spacer and case length (2X the spacer weight is a little conservative).

 

[Bob Scott]

I was mainly concerned that the case itself wasn't being considered. I my build, I'm simming with H motors that are going in a 3 grain CSI case, so there will likely be one spacer. Sounds like it won't make that much difference.