Q&A for How to Make a Powerful Air Pressure Rocket

Water is heavier than air. This makes water a denser and heavier exhaust, thus allowing the rocket to go higher.

The gap isn't 100% airtight, so air is leaking out of it. So you need to pump it quickly so that the pressure can build up.

To hold the water in bottle as well as to be able to inject the bike pump to get air into the bottle, creating pressure for the launch.

Three because four will add weight causing the rocket not to go as high.

It depends on what type of school project. If it is for an air-pressurized bottle rocket, then yes.

Using a denser material decreases range. The water is just there as a propellant.

Yes, it can, but it shouldn't be too much thinner.

Theoretically, yes. Launch sideways and time how long it takes for it to reach a certain point.

Not necessarily. Soapy water looks much more interesting, though, and it's always fun to try new things out. Give it a shot at home and see what happens.

Yes, because the air needs to go into the bottle to build up the pressure for creating the thrust as the water comes out.

It will go higher; the more fuel that's added, the higher it goes. For a higher launch, keep it at 90°; for a distant launch, keep it at 45°.

You could, but be careful not to bend the tip or else it could send your rocket in a wonky direction.

To build up the air pressure required for launch.

Yes, but the optimal angle for height is 90° and the optimal angle for distance is 45°.

Because of how small it is, it might even go farther! The small size makes it so the pressure increases faster, so it builds up more force. It should shoot off faster, and go for a longer distance.

No, the reaction won't be the same. Stick to what it says, or it won't work the same way.

No, you don't. The bottle will still fly without fins, but may not fly as straight. The fins are not necessary. However, the fins stabilize the rocket and help it launch higher without shooting off to one side, so they are a good addition to make.

It could work but you would have to empty most of it and it would not go as high since it is not as dense.

Technically yes, but you would have to pump a lot. Or, you could use an electric pump which can be twenty dollars to even forty dollars.

You can't the way this method works. You would need a much stronger propellant, stronger body frame, etc. Even the most powerful model rockets can barely reach the lowest storm clouds.

You can only use a cork. This is because it keeps water from coming out, but at the same time lets air in. Nothing else can do that.

You can use most pumps, as long as the pressure can build up. Without pressure, it will not blow.

No, as there will be no space for the compressed air to build-up and launch your rocket. Try with varying water levels and see what works best.

Any such rubber stopper will do. You can find these in the science equipment store.