Latest Update: 6th December 2018 - Day 201 - Flour Rockets

Glossary

This glossary contains some terms generally associated with water rockets.

Term Description
Apogee The point at which a rocket reaches the highest altitude.
AR Booster The Air Reservoir Booster is a feature added to launchers to increase their performance. The air reservoirs supply high pressure air through the launch tube to the rocket as the rocket is moves along the launch tube.
Blow-through A term referring to the effect where on launch the air emerging from the lowest coupling punches a hole in the water - blow-through - all the way to the nozzle, this allows some air to escape and hence dropping the pressure quickly inside the rocket. This causes a rocket to under perform.
(see Flight Log Day 26)
burnout A term generally used to describe the point in time when the rocket stops producing thrust as result of the internal pressure equalling the external pressure.
FC Flight Computer
High Pressure A loose term defining pressure used inside of a rocket, launcher or air supply. Generally 200psi or greater is considered high pressure, as this exceeds the normal burst pressure of standard PET bottles. The term does not necessarily relate to the power of a water rocket. A more indicative measure of a rocket's performance is described in the Water Rocket Power Definition section below.
Jet Foaming A technique developed to generate high density foam inside a water rocket to alter the rocket's thrust profile.
(see Flight Log Day 27)
Low Pressure A loose term defining pressure used inside of a rocket, launcher or air supply. Generally pressures below 200psi are considered low pressure, as these are below the normal burst pressure of standard PET bottles. The term does not necessarily relate to the power of a water rocket. A more indicative measure of a rocket's performance is described in the Water Rocket Power Definition section.
NOAA Nosecone - Off - At - Apogee. A parachute deployment technique where the nosecone is suppose to fall of as the rocket reaches apogee allowing the parachute to fall out.
PLP PL Premium - a glue commonly used for splicing bottles together.
TDD Trevor's Deployment Device. This device acts as a pressure switch for detecting when the pressure inside the rocket drops back to atmospheric pressure. This is the point at which the rocket stops producing thrust. It is used to initiate parachute deployment or staging mechanisms.
Tornado Coupling /
Tornado Tube
A threaded hollow coupling that is able to join two bottles neck to neck. Each bottle just screws into the each end of the coupling.

Water Rocket Power Definitions

The following power terms are adapted from the model rocket motor classification. Because water rockets have a continuum of power available based on pressure and volume and don't use discrete motors with specific total impulse ratings, only 3 general classes are defined

Class Total Impulse Range Description
Low Power below 20Ns Example: A 1.25L rocket launched at 80psi.
Mid Power 20.01Ns - 160.00Ns Example: A 6L rocket launched at 120psi.
High Power 160.01Ns - and up Example: A 20L rocket launched at 250psi

More Glossaries

A very good glossary of water rocket related terminology is here:

http://bradcalv.customer.netspace.net.au/wrbook.htm#glossary

Some other useful terms are described here:

https://web.archive.org/web/20130507113038/http://www.paul.grosse.is-a-geek.com/h2orfaq.htm