Nosecones for MicroMaxx Model Rockets

This is a collection of model rocket nosecones for MicroMaxx size T-MM body tubes.

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Thingiverse is having a lot of trouble managing this quantity of files. They are not necessarily the most up-to-date or the full collection. The latest and complete set of files are available here: https://rocketshipgames.com/rockets/parts/nosecones/stl/t_mm/
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Note that there are over 1GB of models in this collection. You may want to consider using the Files tab to only download those you wish to use.

Updates

• 2021/04/45: A slight discontinuity at the transition in the blunted conic and blunted tangent ogive nosecones has been corrected (new files available at the link; the files are unmanageable on Thingiverse).

Shapes

Currently included shapes and their parameters are:

• Conic
• Biconic (discontinuity at 1/3 length of 2/3 diameter)
• Blunted Conic (tip diameter of 1/3 caliber)
• Ellipsoid
• Parabolic (k of 1, a full parabola)
• Power Series (power of 0.25)
• Tangent Ogive
• Blunted Tangent Ogive (tip diameter of 1/3 caliber)
• Secant Ogive (ρ of (L+(R²+L²)/D)/2; a slight bulge)
• Haack (c of 0, Von Kármán, minimizes supersonic drag for L and D)

These have been generated at several lengths:

• 1 caliber (7.16mm)
• 2 caliber (14.32mm)
• 3 caliber (21.48mm)
• 4 caliber (28.64mm)

They all have a roughly 1/2 caliber (6mm) plug (shoulder).

There are three variations of fill and shock cord anchor:

• SHELL---the plug and bulb are simply an empty shell
• SOLID---the plug and bulb are filled solid
• PLUGGED---the plug is filled solid but the bulb is a shell
• BAR---the plug and bulb are a shell, with a rounded bar across the bottom
• TAB---the plug and bulb are a shell, with a small tab at the bottom with a hole in it
• SIDE---the plug and bulb are a shell, with a larger tab at the bottom with a hole in it

A rendered cutaway image included in the files illustrates each of these fill & anchor styles.

Use SHELL to glue a shock cord directly to the interior of the plug or bulb, SOLID or PLUGGED to drill a hole and attach an eye hook to the plug, and the others to have an integral anchor point to which to tie the shock cord. The SOLID version should be stronger if you are having issues with the nosecones snapping between layers.

Printing

The SOLID and PLUGGED styles should be printed with 100% infill so that the plug is actually solid and the hook can be screwed in. Infill doesn't matter much for the other versions, the bulb as well as the unfilled plug are just 1mm shells.

Typically these T-MM nosecones should be printed with a brim as otherwise the surface area of the initial layer is too small to adhere well, even for the solid variants. It will also help to print several at a time close enough for the brims to connect. The automatic layout determined by most slicers should be fine for this.

Printing more than one at a time can also help produce cleaner tips on the pointier nosecones. Sometimes prints of tall, narrow shapes are swirled by the hotend. When the area of each layer is very small, the hotend circles around and around reheating the printed filament before it has time to cool and set properly. As the print gets taller and weaker the distortion builds and can become quite visible. Simultaneously printing another shape of the same height usually forces enough time for cooling between layers without tweaking settings to address the issue. On large prints of other kinds of models you can add a sacrificial pillar of the same height. But in this case you should just print more than one nosecone of the same height, and then you'll have twice as many! Otherwise you can adjust the minimum cooling time per layer in order to get smooth tips. Note also that the conic and tangent ogive shapes have spherically blunted versions which print more cleanly.

There is 0.25mm of tolerance between the plug and body tube. Quite likely in order to slide smoothly the outer bottom edge of the plug may have to be sanded or scraped to remove the elephant's foot bulge created by the initial layers` interaction with the print plate.

Tube Source

These have been tested to fit well with the T-MM body tubes available from Aerospace Specialty Products (ASP).

Requests

Send a message, leave a comment, or email [email protected] to request other parameters or basic shapes; they can probably be generated easily enough.