Water Rocket News
Design Principles
-------------------An AntiGravity Research Corporation Publication------------------

AntiGravity's water rockets have all been designed with safety, high altitude, durability and simplicity as the four central goals.  Fortunately, these requirements are all mutually reinforcing, as follows.
1.  The things that we did to the rocket to improve safety also improved altitude, simplified it and made it more durable.
2.  The things we did to reach high altitude also made it safer, simpler and more durable.
3.  The improvements in durability also made the pop bottle rocket safer and simpler and improved altitude.
4.  The improvements in simplicity we made to the water rocket also improved safety, altitude and durability.
In the table below the design requirements we set for all our pop bottle rockets are listed in the column at the left.  In the four adjacent columns are listed the effect that the requirement has on our goals of safety, high altitude, durability and simplicity.

Design Requirement
1.  Safety
2. High Altitude
3. Durability
4  Simplicity

Rocket should travel slowly (100 km/h or less)

in case it hits something or someone.

to minimize air friction, which causes the greatest loss of energy.

to minimize the self destructive impact when it hits the ground.

to minimize the structural requirements for fins, launcher, and recovery method.


Rocket should be as light as possible (approximately 60 grams for any stage).

in case it hits someone or something.

to minimize the weight that it has to lift, maximizing altitude.

to minimize the self destructive impact when it hits the ground

to simplify the touchdown shock-absorbing system and eliminate the need for a recovery parachute, which eliminates even more weight.

Rocket should be pressurized from a safe distance away (25 feet).

in case of a bursting bottle.

so it can run at a higher pressure, for more altitude.


people aren't as likely to step on, trip over, or handle the rocket when they aren't near it.

AntiGravity's launcher is the world's simplest because of this requirement.

Filling hose should self-release before over-pressure is reached (at approximately 80 psi)

to prevent the bottle from bursting

a rocket doesn't fly very high at all if the bottle bursts.


a rocket that doesn't burst is always more durable than one that does.

AntiGravity's launcher is the world's simplest because of this requirement.

Everything on the rocket should serve a useful function.  No decoration or frivolous add-ons.


it's much easier to inspect all functional parts when all parts are functional, and none are covered up.
Less weight is much safer if the rocket hits someone.

any unnecessary add-ons increase the weight and drag of the rocket.  Eliminating these increases altitude.


unnecessary extra weight makes for greater collision impact.  Eliminating this improves impact survivability.

what could be simpler than leaving off unnecessary parts?

Each rocket or stage should have a soft bumper attached to the front of it.


impact is soft and harmless to people and things.  The bumper always works, whereas a parachute doesn't.

the lowest friction nosecone at the rocket's low velocity is a truncated conical frustum, approximated by the bumper pad.


all parts of the rocket last much longer because of the impact-absorbing characteristics of the bumper (approximately 50 flights)


this is much simpler than a parachute deployment system, and it's 100% reliable, whereas a parachute isn't.