Troubleshooting your AntiGravity Water Rocket
When you run across a problem with your 1-, 2-, 3- or 4-stage rocket, there is almost always something you can do to solve it. Here are some of the solutions that you can try.
1. The rocket doesn't go very high and the stages tip sideways before separating, or don't separate at all.
This is usually caused by low pressure in the rocket. If you are using a hand-powered bicycle air pump, you should be pumping about 70 pumps per 2-litre bottle (i.e 200 to 220 pumps for a 3-stage rocket. or 70 pumps for a single stage) before launching. Or if you are using an electric powered air compressor, you should have it set to provide 120 psi to the launcher hose, because there is a pressure drop from the inside of the yellow bulb to the inside of the rocket of about 20 to 40 psi. When the rocket pressure relief valve starts whistling, then you should launch the rocket by disconnecting from the pump or compressor.
2. The middle or upper stage lifts off by itself.
This is usually caused by the three interstage clips not being aligned inside the clip guides of the ring fin they are trying to hold on to. The clip guides (they look like 3 pairs of very thin fins around the ring fin) have a soft foam material in between each pair that the clips can grip onto and hold. If the clips are trying to grab onto the hard material of the fin, they will just slip and let go of the ring fin too soon.
3. The rocket lifts off by itself before the pressure is high enough for a good flight.
This can be caused by the yellow launcher bulb not being fully inserted into the booster nozzle. Or it might be because the friction between the inside of the nozzle hole and the yellow bulb is too low. You can solve this by using some 100 grit sandpaper to lightly radial-scuff the outside surface of the launcher hose's yellow bulb (sand the bulb around, not lengthwise.
4. Air leaks out of the quick-connectors when I pump up the rocket.
This can be caused by an uneven surface or scratch in the thin plastic launcher hose. Remove the hose from the quick-connect by pressing in the release ring and gently twisting and pulling out the hose. Then neatly cut off and discard about 1/2 inch (1.27 cm) of the thin hose, and re-insert the hose into the quick-connect. The new smooth, clean hose surface should seal inside the quick connector much better.
5. One of the rods in the ring fin assembly broke and I can't remove it. How can I remove it?
To remove a broken rod, with one hand grip the ring fin, and use a pair of pliers to grip the base of the rod where it is inserted into the ring fin. Twist the rod radially and gently pull it out at the same time. The same technique applies if you are removing the other end of the rod from the nozzle arms. Then you can insert a new spare rod in its place.
6. The interstage bulb won't fully insert into the next stage.
First make sure that you are trying to insert the correct bulb into the correct nozzle (green bottle top to green nozzle, red bottle top to red nozzle). Sometimes it helps to twist both stages gently back and forth (as far as the clip guides will allow) while pressing the stages together. If this doesn't solve the problem, before trying to insert the yellow bulb into the next stage nozzle, lubricate the yellow bulb with a bit of Vaseline. This always works.