.STL File / 3D model: CHEAP-AND-EASY MODEL ROCKET

Just in time for the Fourth of July! This is meant to be a semi-disposable dirt-cheap model rocket which can be produced in under an hour on a makerbot in 1 print. Since these aren't much more powerful and much more expensive than an A motor, it utilizes standard estes C-class motors. It has performed every time and has been flown three times. It doesn't have a parachute or any other recovery mechanism and on the occasions it've flown I have to retrieve one since it appears to disintegrate when the ejection charge goes off and travels extremely large. It flew at night for the spark trail effects and could not locate it afterwords, but judging by the impressive visible path it flew very far and straight.

Disclaimer: This rocket poses a hazard to anyone in the region, fly just at your own risk and in uninhabited places and has no method of retarding it's descent.

Design Features: The six fins towards the back give this rocket great stability despite its short height by packaging a large surface area behind the center of gravity (provided by the weight of the engine). To be able to keep the height inside the limits of a makerbot I felt the extra fins were a fantastic idea, and besides they look cool. From snapping off some surface area is provided by the ring fin but mainly aids in durability to keep the fins. The engine sits up the rocket body to bring the center of gravity as far forward as possible for stability reasons. The printed part seems to have clearance from the gasses and tapers away from the rocket engine, but nevertheless may present some fire hazard although this has not been detected in any tests.

Instructions

1) Print out the rocket body by means of 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 item prints much more nicely with the Ducted cooling fan by Iwo http://www.thingiverse.com/thing:5756 If this is not available, the integrated side-fan does acceptably, but some cooling is recommended because without it the main tube will be bumpy and uneven.

2) Reduce 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) Add an Estes "C" engine at the tube as far as it will go. The motor's end edge needs to be flush with the start of the taper. The tube is intentionally oversize for ease of loading and ejection. Until it's just held in by friction Wrap a layer or two of tape in a couple of points of the engine. Glue or adhesive works too, if you're idle, but it is a flight afterward.

4) Connect the ignition wires and start in a safe area. I recommend using upside-down turned in the bottom for a launch platform with a hole cut. Lugs aren't needed, it will fly straight as long as the initial launching site is level.

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