Very good idea! If you contain the acrylic in a metal combustion chamber instead of relying on the acrylic to contain the pressure, then you could run the engine until the fuel is exhausted with no real worries. And this would allow you to run as much O2 as you need for the best ratio. I would really really like to see this attempted. There is a LOT of potential energy in acrylic, and with how evenly and predictably it burns, I think it might be a very practical fuel for hybrid engines.

This is great Ben.  I love the fact that you can see inside the engine while it’s lit.  I’m looking into building a hybrid rocket motor myself.  If you know of any good resources for designing the nozzle I’d love to hear them.  I’m not too sure about how to calculate the different angles, throat diameter, etc.