Air Rocket and Fin Collar

thingiverse

I designed this rocket and fin collar for a great air rocket launcher I got from the Maker Shed (http://makershed.com/products/compressed-air-rocket-launcher-v22). I wanted my second-grade students to see the rocket in flight without fins, then design and easily attach their own cardboard fins for testing. The rocket has a small ridge that fits into a groove on the inside of the collar to prevent spinning during flight. The air rocket is quite powerful, so we wear eye protection, and the kids stand well back. The difference in flight is obvious, and the students enjoyed the whole experience very much. Post-printing cleanup requires a couple of shaving passes with an exacto knife to fit the inner rim of the rocket body and the collar perfectly. The rocket file has no text on it, and the collar does not have a notch for the text. The collars stay on the rocket body during flight and return but sometimes break if it lands wrong. I suggest printing several collars. The fins stay put during launch if they have 1/2 to 3/4 of an inch of cardboard sticking out of the tail end. The launcher requires assembly, so allow time for that. Older students can do it. The launcher valve can be tricky. A helpful tip from Air Rocket Works is: "If the Quick Exhaust Valve Leaks: Sometimes, when using a bike pump, the QEV diaphragm will fail to seal the outlet, and air will leak out the launch tube with each pump. First, complete one stroke on the bike pump while the slide valve is in the 'Launch' position. This builds up pressure in the hose of the bike pump. Next, slide the valve to the 'Pressurize' position. The sudden inrush of pressure built up in the pump hose will almost always seat the QEV diaphragm."