I'm trying to model a rocket's position with air resistance as a factor. The rocket is fairly low-powered (Estes A8-3, 9.7N of thrust for 0.7 seconds), and I estimate it won't be going faster than 50 metres per second.

Should I be using linear or quadratic air resistance for this?

I found online that linear air resistance is used for relatively low velocities. How low is 'low velocity'?