This marks 100 years of continuous weather records for Phoenix. The assistance given by Mr. Robert S. Ingram, former Meteorologist in Charge, National Weather Service Office, Phoenix, Arizona, Mr. Paul C. Kangieser, former NOAA Climatologist for Arizona, and other staff members is gratefully acknowledged.
Most liquid fuels in widespread use are derived from the fossilized remains of dead plants and animals by exposure to heat and pressure in the Earth's crust. However, there are several types, such as hydrogen fuel (for automotive uses), ethanol, jet fuel and biodiesel which are all categorized as a liquid fuel.
Liquid motors come in many shapes and sizes: Most of them are controllable (can be throttled up and down), restartable, are often used as control and maneuvering thrusters. Liquid thrusters can be broken into three main types: monopropellant, bipropellant, and cryogenic thrusters. Monopropellants only use one propellant such as hydrazine. Bipropellants use a fuel and an oxidizer such as RP-1 and H. Cold-gas motors have controllability similar to liquids but are the simpler and lighter. They are basically a high pressure tank with switches which flip between the open and shut state.