Manufacturing and Assembly

All parts of the rocket were made without molds: mostly PLA and ABS 3D printing, cut-and-bond assembly of carbon tubes and adaptation of off-the-shelf components. Making molds did not make sense at this scale in terms of time and material; the modular approach let us produce parts in parallel and reprint any problematic part on its own.

Pressure tank and launch ramp

The main component of the tank is a 1.5-liter PET bottle. It was reinforced by wrapping it with packing tape and, in this form, was verified in tests to withstand 7 bar of pressure. For sealing, a custom nozzle printed in PLA was fixed to the bottle neck with epoxy; the nozzle's inward-tapering conical shape compresses the O-ring on the launch tube to provide the seal.

On the ramp side, 40 cm PVC pipes were connected to a brass cross fitting mounted on a wooden base. A 15 mm O-ring and a 20.5 mm cylindrical PLA part supporting it were fitted onto the tube. The plastic clamps holding the bottle were glued to this PLA part and tightened with a steel hose clamp; a separate PLA trigger part was designed so the clamps grip the bottle neck securely.

3D-printed parts

The STL files in this folder cover all the parts produced; quantities are given in the file names. Highlights: helical baffle (1), elliptical nose cone (1), nozzle (3), sloshing tank centering rings (2+2), rail guide ring (2), movable fin centering part (1), fin retaining latch (20), upper and lower trigger parts, trigger pivot bushing (3) and seal locking parts (2+2). The fins are marked with the NO3D prefix in the file names — these were not printed but cut from sheet.

Assembly sequence

1. The PET tanks are wrapped with packing tape and the nozzles are bonded to their necks.
2. The primary tank is seated on the tube of the lower launch system with an O-ring seal; the trigger is pushed up to tighten the clamps and lock the tank. The launch cord is attached to the trigger.
3. The main frame, built from carbon tubes and PLA spacers, is mounted on top of the primary tank; the attachment points of the upper launch system are also on this frame.
4. The mechanical elements of the upper trigger system and the electronic components that control it are installed.
5. The sloshing tank carrying the helical baffle is seated with its centering rings; then the movable fin assembly and the nose cone housing the avionics are mounted.

The key feature of the assembly is that it is reversible: the tanks can be removed in under two minutes for maintenance and refilling.