Model Rocket

These are model rocket modular parts that are compatible with Estes BT-50 rocket (0.98 inch diameter) tubes. In short:

rocket = stage + tube + nose

multi stage rocket = booster + stage + tube + nose

rocket with payload = stage + tube + payload + nose (see https://www.thingiverse.com/thing:7067681)

IMPORTANT: See https://www.thingiverse.com/thing:7056020 for more parts, with more fin, nose cone and tube options, including reinforced tubes. These parts are all interchangeable.

First you select a 'stage' (holds a standard engine, has 3 fins and a launch lug) and optionally (for a multistage rocket) a 'booster' section (holds a booster engine, has 3 fins and a launch lug and attaches to a stage section) and nose cone options, and assemble with a shock cord (e.g. kevlar thread) and parachute. You then use a tube of the desired height (either printed or cardboard) to connect to the nose and stage sections. Booster sections (if used) just slide underneath into the stage section. Both the nose cones and stage sections have attachment points for shock cord and parachute. This lets you build a rocket without the use of glue. Note that you only use the booster sections for multistage rockets.

The total weight of the example rocket shown in the pictures is 35g without engine and 53g with engine. The parts were printed with 15% infill. These V2 parts are weight reduced over the V1 parts, where they may weigh up to 20% less than the original parts. V3 simply adds the ability to have multi-stage rockets, where a booster section would use a booster engine. The stage sections would use standard engines. There are no compatibility issues between parts from V1, V2 or V3. New nose cone and fin patterns have also been added in the new versions.

A V4 OpenSCAD file has been added with the ability to set a cant angle on fins. You can use the OpenSCAD file and set parameters to generate STL files boosters or stage sections with the desired cant angle (typically 0 to 7 degrees). Note that the booster sections will only connect to an upper stage that does not have a cant angle. When posted, the STL files with a cant angle will have names like StageV4-2-3d (which would indicate a 3 degree cant angle).

The stage and booster sections are designed to accept engines with dimensions similar to A8-3, B6-4 and C6-5 (i.e. 18mm diameter and 70mm length). The engines will fit snugly into the section. In case they are for some reason loose (e.g. due to printing issues), there are small screw holes that can be used to better secure the engine with a 6 or 8mm M3 screw/bolt .

STL files for 2, 4, 5, 6, 7, 8 and 10 inch tubes are provided, as an alternative to cardboard BT-50 tubes. These are comparable in weight to the cardboard tubes. They print and fit with the other components surprisingly well. They are also more durable than the cardboard tubes.

These printed parts will be a few grams heavier than the use of cardboard and balsa alternatives, but they work and better survive launches. I use PLA and PLA Plus. I tried Lightweight PLA, but it did not print well (stringy) and did not save more than a few grams for each part (i.e. not worth the pain or cost). Except for clearing out and smoothing the inside of the launch lug (with a small round file) these parts should print very nicely without supports and not require any sanding. The printing of tubes may require a brim.

The launch lug on each stage and booster section is designed for either a 1/8 inch or 3/16 inch (STL files ending with _3-16) launch rod. Be sure to use a small round file to smooth out the inside of the lug after printing to insure smooth launches.