I recently built a model rocket with t' capacity t' launch a GoPro 1300ft into t' air. Blimey! Blimey! T' determine what size solid fuel engine I should use, ya bilge rat, I weighed me rocket and then tripled that weight. Begad! Blimey! For a rocket o' me size I needed t' engine t' have a average thrust o' 30 Newtons. Blimey! Blimey! In addition, t' reach a height you desire, me bucko, you have t' look at another factor as well. T' total impulse, matey,  this is a measurement o' t' average thrust times t' total time o' firin' (ie. Blimey! Blimey! sec). Well, blow me down! Blimey! This measurement will determine t' total amount o' energy (impulse) t' engine will provide. In t' end, I went with two F15 size engines. Avast, me proud beauty! Blimey! (15 equalin' t' average thrust in N). My rocket reached expected height and t' engines performed flawlessly.  One more thin' I should mention.. Aye aye! Blimey! Each model rocket engine comes with an ejection charge. At t' rocket apogee this ejection charge will back fire up t' rocket tube creatin' a pressurization charge which will eject t' recovery device. I this video it is clear that me parachute did nay deploy. Avast, me proud beauty! Blimey! When t' engine chamber reached very hot temperatures me glue points began t' weaken. So that when t' ejection charge fired t' pressurization build up simply shot t' engines out t' back o' t' rocket instead o' deployin' t' parachute.