This is small fun model of rocket engine that propels an inflatable balloon. It has 3 nozzles that are in a helix shape and thus help stabilize the nominal trajectory. Baloon can get quite high, but it is prone to wind. Although this is model iteration 7, it is still rather experimental. I’ll be glad if you improve it even more ;).
You can inflate it directly through the engine or use the inflating adapter. Baloon that is harder to inflate is better.
Hold the balloon just above the engine neck or place it on a flat surface and release.
Print the engine with 1 perimeter, 0 infill, 0 top and 0 bottom layers (similar settings as for RC planes printing). So you get the engine as light as possible (3.5g).
In the files below you can also find the old V2 version, V7 version without outer shell and V7 engine for SLA print.