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levansic

TP Tube Rockets

by levansic Aug 15, 2016
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Is this designed for 13mm or 18mm engines?

Printed these at 96% to fit a generic paper towel tube.

SCALE TO 110% TO FIT UK TOILET ROLLS!!!

This means you need to modify the rocket engine mount either by padding it or adjusting the STL, I may upload my remix when I've cleaned it up a bit but don't print this stock if you're in GB.

Comments deleted.

We did some more testing and experimenting this weekend, and found out some interesting results.

First, not all recovery wadding is the same. Our original tests we're done with a very lightweight wadding from Estes. This wadding is like the most ineffective single-ply toilet paper you could imagine treated with a flame retardant. It was light and worked great!

This weekend, we used a different batch that was in the cabinet of our Physics classroom. This wadding was thick and soft. It looked like super-premium toilet paper. Well, it weighed significantly more, and when we used the eight sheets that worked so well for the thin paper, it made it difficult to stuff in the parachute. It was so heavy and frictive, that this wadding did not come out of the rocket on chute ejection. It also was heavy enough to impact the rocket performance, causing a very low deployment of the recovery chute. A tail fin broke off, as the landing was very rough.

With small engines, and relatively large drag devices, crosswinds can have a huge effect! High crosswinds combined with imbalance around the central axis can make the twist rockets go from spiral to wobble to tumble. Gyroscopic inertial stabilization only works well if the rocket is well balanced. A high crosswind will push the tail fins, making the rocket rotate around its Center of Gravity (CG). A non spinning rocket will passively accelerate through this, possibly rotating to an orientation that reduces drag relative to the crosswind. A spinning rocket will start to wobble. The stronger the crosswind, the more severe the wobble will be.

All rocket experimenters must be alert.

This is great. What plastic are you using? Does the engine fuse to the base due to the heat? Can you get multiple shots from the rockets?

I used natural Makerbot PLA for the tail cones. The engines do get quite warm, but do not fuse to the plastic when launched. We've done multiple launch, recover, relaunch, repeat cycles. There are a few black streaks on the interior from the ejection charge, but no damage. The limiting factor will be physical damage due to rough handling, depending on how light you decide to print.

We have stuck to the lower power A8-3 engines to limit our drift (lots of wind here). I would say that you will have an indefinite service life with these engines.

The nose cone of our most-used rocket is showing far more wear than any of the tail cones. Again, this is due to light printing and rough squeezing from non-gentle hands.