check out harvel.com they give dimensions of all types of pvc including sdr 21. this will give a very good and tight fit on gold balls they have a diameter of about 1.693 inches; 1.5 inch OD sdr 21 has an ID of 1.7 inches. golf balls need a little help from ram rod to fit in 1.5 inch sdr 21. Make su...

if you want a parachute system, try using some ideas that have been used with 2 liter bottle rockets that use water and air. You can google this, and their are several links that still work explaining various eployment systems. I personally like the idea of using a wind up toy idea.

if you are using 2 liter or 1 liter bottles, most of them will fit over 1/2 sch 40 pvc pretty tightly. I used a 4x4 piece of wood for the base of my launcher. Added some legs perpendicular to the base for side to side support. There is a vertical launch tube which bottle slides over after being fill...