Cheap-and-easy model rocket

thingiverse

Just in time for the Fourth of July! This is intended to be a semi-disposable dirt-cheap model rocket that can be produced in under an hour on a makerbot in only one print. It uses standard inexpensive estes C-class motors since these are not much more expensive than an A motor and much more powerful. It has been flown three times and has performed well each time. It does not have a parachute or any other recovery mechanism and on the occasions I've flown it I have yet to retrieve one since it travels extremely high and seems to disintegrate when the ejection charge goes off. I flew it mainly at night for the spark trail effects and couldn't find it afterwords, but judging by the impressive visible trail it flew very far and straight. Disclaimer: This rocket has no method of retarding it's descent and presents a potential hazard to anyone in the area, fly only in uninhabited areas and at your own risk. Design Features: The six fins towards the back give this rocket good stability despite its short height by packing a large surface area behind the center of gravity (provided by the weight of the motor). In order to keep the height within the limits of a standard makerbot I felt the extra fins were a good idea, and besides they look cool. The ring fin provides some extra surface area but mainly aids in durability to keep the thin fins from snapping off. The motor sits partway up the rocket body to bring the center of gravity as far forward as possible for stability reasons. The printed part tapers away from the rocket motor and seems to have enough clearance from the hot gasses, but nevertheless may present some fire hazard although this hasn't been observed in any tests yet. Instructions 1) Print out the rocket body using a makerbot with ABS on standard default extrusion parameters. I used the Acetone-scrap ABS film trick (as detailed here: http://www.thingiverse.com/thing:7460) to avoid the need for a raft. NOTE: this thing prints much more nicely with the Ducted cooling fan by Iwo http://www.thingiverse.com/thing:5756 If this is not available, the built in side-fan does acceptably, but some cooling is recommended because without it the main tube will be bumpy and uneven. 2) Trim up any bumps and brush the fins and outer surface with some acetone, this helps seal up any gaps in the fins and boosts strength tremendously. 3) Insert an Estes "C" engine in the tube as far as it will go. The end edge of the motor should be roughly flush with the beginning of the outward taper. The tube is deliberately slightly oversize for ease of loading and ejection. Wrap a layer or two of tape at a couple of points of the motor until it is just held in by friction. If you're lazy glue or acetone-abs paste works too, but it is definitely a one-shot flight then. 4) Connect the ignition wires and launch in a safe area. I recommend using a disposable cup turned upside-down with a hole cut in the bottom as a launch platform. Launch lugs are not needed, it will fly straight so long as the initial launch site is level.