“Maybe” Fail-Proof Way to Make a Bottle Rocket Taught by Malvern Panalytical Engineer

Materials

The faucet nipple is available in the gardening supplies section of large Daiso stores.
It may not be available in Daiso’s medium-sized stores (Chusou) or small stores (Shousou).

If there is no large Daiso store nearby, please purchase the following substitutes at Konan.

Materials (Substitutes)

If there is no large Daiso store nearby, please purchase the following two substitute items at Konan.

Benefits: No additional processing of the hose coupling needed with a hacksaw and drill
Drawbacks: An extra cost of 276 yen!

(Using only the Konan parts for the hose coupling side can also eliminate the need for additional processing)

Necessary Tools

Instructions

Step 1: Rocket Body

Cut one of the PET bottles in half with a cutter.

Roll up a half-page of newspaper to use as a weight and insert it into the upper half, securing it to the bottom of another PET bottle with duct tape.

Step 2: Exhaust Nozzle

Hollow out the inside of the PET bottle cap.

Use a hand drill to make numerous small holes in a circle and then cut them out with nippers.

Then, smooth it with a file.

Only cut out the inner part of the cap.

Be careful not to cut up to the part that contacts the mouth of the PET bottle.

If you fail, use the cap of another PET bottle.

Create numerous horizontal scratches with a file on the exterior of the hollowed-out cap. These grooves allow the adhesive to provide grip like nails, preventing the cap from slipping when the adhesive bond breaks.

Thoroughly mix two-part adhesive. It hardens through a chemical reaction.

If using a single-part drying adhesive, excess adhesive may not dry inside, leading to insufficient sealing and potential air leakage.

Adhere the PET bottle cap to the inside of the white part of the faucet nipple. Discard the black part.

Generously apply adhesive up to the outside of the nipple to prevent air leaks.

However, be careful not to seal the hollowed-out holes or let adhesive touch the inside of the cap; this would prevent screwing it into the PET bottle.

Step 3: Launcher

Modify the hose connector.

Unscrew the cap.

Cut off the black protrusion with a hacksaw.

Widen the central hole to allow a bike valve through by drilling with an 8 mm diameter drill.
(If you lack a drill, widen it with a file)

This processing is unnecessary with Konan parts.

Trim the rubber part of the bike valve with scissors or nippers to minimize it.

Unscrew the upper part and disassemble it into three pieces.

Press it into the hose connector and ensure the threaded part extends sufficiently.

Place the valve, with its screw removed, on a pencil tip, coat it liberally with adhesive, and press it into the spray connector.

Avoid adhering the adhesive to the connector’s inner side surfaces.

After pushing in the valve, apply adhesive externally as well.

Hang the metal screw part with a clothespin, aligning the screw and connector for curing (preferably for one day).

Once the adhesive fully cures, reassemble the bike valve.

Insert the insect rubber-equipped part into the groove and secure it by tightening the top screw.

The plastic cap is optional to fit.

After the adhesive cures entirely, attach the cap to the PET bottle.

Insert the bike valve-equipped launcher until it clicks.

If insertion is difficult, remove excess adhesive.

Use a bicycle pump to inflate three times. (Do not inflate more) Check for air leaks making a “hissing” sound. If air leaks, generously reapply and harden adhesive at leak points.

Hold the PET bottle, tug the stopper to verify a “pop” sound release.

If no “pop” sound, air leaks exist.

If removal requires strong force, apply grease (Nivea or Oronine) on the O-ring (black rubber) for better slip.

Attach vinyl tape weights to the launcher’s stopper.

For one vinyl tape of the three, remove the inner cardboard until the stopper barely fits. For the other two, completely remove the cardboard.

Place the partially de-cardboarded vinyl tape on top, the fully de-cardboarded tapes below, and bind the three together.

Apply adhesive (non-two-part) on the stopper, attaching it to the vinyl tape weight.

Finished Product

It’s complete.

How to Play

Assemble the launcher and PET bottle rocket, inflate about five times with a bicycle pump. (Excess inflation is dangerous) Pitch it onto a launcher set at 45 degrees. When the valve hits the base, the stopper releases, detaching the rocket for launch.

Never peek into the launcher upon rocket insertion. It will hit your face.

Operating Principle

1. The valve contacts the base of the launcher.
2. The weight descends due to inertia when the valve cannot move downward, pulling the fixed stopper and detaching it.
3. Detaching the stopper separates the launcher and rocket, and pressurized air rapidly exhausts from the rocket’s bottom, reacting to propel the rocket upward following Newton’s third law of motion.

Precautions

• A PET bottle can withstand around 1.6 MP (16 atm), equivalent to air from sixteen bottles. However, the adhesive’s pressure tolerance is unknown, so avoid over-inflation.
• Filling the PET bottle halfway with water before launching significantly enhances flight, but excessive flight increases impact risk. Exercise caution.
• Before launching, ensure no person stands in line with the launcher barrel’s extension.