Welcome! There's a new tool in town, he's called
OpenRocket, and he's absolutely free! Build a virtual rocket, insert a virtual motor, see how high she'll go, best delay time, top speed, speed off the rod/rail, etc. If you're building a kit you'll probably be able to find a file for it, there are files for hundreds of kits and even more for scratchbuilts.
Other fun things you'll find out about, if you don't already know: Railbuttons for every rocket size; launch rails are far superior to rods IMHO. Jolly Logic Chute Release lets you do dual-deploy without ematches or BP charges. Q-Jet composite motors are the same size as Estes (18x70mm) but can deliver twice the impulse of BP; there are also 24mm Q-Jets. Altimeter kits starting at about one-tenth of the price of some of the altimeters you remember (Eggtimer Quark fits a BT50, does dual deploy, and beeps out the altitude, for under $25). Mach1 rocketry has fiberglass tubing in the same sizes as Estes body tubes if you want to build a hard-to-destroy rocket. In addition to regular single-use motors and reload kits, Aerotech has "Disposable Motors", single-use except that the delay can be adjusted. (Delays can be adjusted in reload kits, too.) All sorts of propellants to choose from, Black Jack, Fast Black Jack, Warp9, Super Thunder, etc., etc. Lots of high-power kits from multiple vendors. Wireless remote systems for launching between one and 64 rockets. Research rocketry is here: Tripoli L2's are allowed to make and fly their own composite motors at TRA launches. The list goes on and on. You are about to commit...fun!
