openMotor VS openrocket

keep away from PVC tubes, cause those shatter rather than peel like with cardboard or aluminium tubes. and unlike aluminium, it doesn't turn up in x-rays. don't follow online video tutorials, cause they're often simplified massively and don't explain the complexities. anyways, here's an online video tutorial (ironic) series by someone who's built much more complicated motors than pvc tubes packed with sugar. He does this at MIT, and also co-made OpenMotor, a software to get estimated chamber pressure, KN (a value proportional to the chamber pressure and surface area of burning, can't remember the exact formula for it), and thrust, plotted on a graph relative to time. There's also this site, which is basically the archive of someone who's been building amateur motors for decades, and it contains hundreds of separate pages, most of which contain extremely useful information, especially the theory section. I'm currently designing my own motor using sugar too, and these have all been a massive help.

You’ll also need a casing capable of safely handling the pressure, so you might as well just get a commercial reloadable motor at that point. It would be a good idea to take a step back and stop making your own motors until you have enough experience with reloadable motors to understand how they work. A good way to get familiar with the design aspects is to try replicating the performance data from existing motors in OpenMotor, which you can also use to design experimental motors around a commercial motor case.

https://openrocket.info/ download this to design and simulate the model rocket

get Open Rocket https://openrocket.info/

The thesis that is the basis for OpenRocket is really good and well worth reading.

model it in OpenRocket first and see where your center of pressure is. once you find that (it will give you distance in cm or in from the tip of the nose), balance it on your finger to find your center of mass / center of gravity. your Cg needs to be closer to the nose than your Cp. ideally, you want the Cg to be at least 1x to 2x the diameter of your body tube forward of the Cp. the body tube width is referred to as 1 caliber, or 1 cal, so you will see stability measurements expressed like 1.5 cal or 2.6 cal.

I would start with downloading the open source OpenRocket program and playing with that. That could keep you busy for several weeks!

As for picking the motor, rather than do guess work, if you haven't done so already, use a software like OpenRocket (https://openrocket.info/). You can recreate your rocket in it, and it will give you a selection of literally every single motor there is to simulate with. Just make sure the weight, the center of gravity, and the overall shape of your rocket is right so that you can make sure the simulations are accurate.

If you are going to be making rockets and simulating rockets, I highly recommend a software like https://openrocket.info/. Software like this is how most people design their rockets.