OpenRocket 15.03 - Compressed Air Rocket Simulaton Question

Hello,

Is there a way to simulate a compressed air launch of a compressed air rocket in OpenRocket? I've managed to construct the rocket in the software, but I don't see anyway to simulate it outside of adding an engine. If anyone knows how I could simulate this in OpenRocket I would really appreciate it.

Please let me know if I need to provide additional information.

Thanks,
Jeff

You most likely have to put in a dummy motor.

I was thinking that would be the case. I know nothing about model rocket engines. Could anyone offer some guidance on setting up a dummy engine, or an engine that would provide an initial thrust that would mimic compressed air launch?

Full disclosure, I'm coming at this project blind and with miniscule direction from the instructor. So I apologize in advance for my ignorance, and appreciate the patience.

You have to define a motor file that specifies the thrust vs time of the motor you have. Doing that is a little complicated.
https://www.thrustcurve.org/raspformat.shtml discusses the RASP format, which would be easiest to define by hand.

Here's a really good paper that somebody in Germany did on water rocket flight performance, including thrust curves. Using the math and the particulars on your water rocket motor, you should be able to come up with some reasonable numbers to use in creating a RASP file. The thrust curve looks more like a mortar blast than a rocket motor... https://www.schulphysik.de/strutz/predictors.pdf