I recently built a model rocket with the capacity to launch a GoPro 1300ft into the air. To determine what size solid fuel engine I should use, I weighed my rocket and then tripled that weight. For a rocket of my size I needed the engine to have a average thrust of 30 Newtons. In addition, to reach a height you desire, you have to look at another factor as well. The total impulse,  this is a measurement of the average thrust times the total time of firing (ie. sec). This measurement will determine the total amount of energy (impulse) the engine will provide. In the end, I went with two F15 size engines. (15 equaling the average thrust in N). My rocket reached expected height and the engines performed flawlessly.  One more thing I should mention.. Each model rocket engine comes with an ejection charge. At the rocket apogee this ejection charge will back fire up the rocket tube creating a pressurization charge which will eject the recovery device. I this video it is clear that my parachute did not deploy. When the engine chamber reached very hot temperatures my glue points began to weaken. So that when the ejection charge fired the pressurization build up simply shot the engines out the back of the rocket instead of deploying the parachute.