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DEFINE volatility
- the measure of a liquid's ability to convert to a vaporous state.
- Not to be confused with a fuel's volatility rating
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DEFINE flashpoint
the lowest temperature of a combustible substance (fuel) that would ignite with a momentarily application of a flame
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DESCRIBE how temperature affects flashpoint, given a certain volatility
Increasing temperature increases volatility
As volatility rating increases, the flashpoint decreases.
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STATE the characteristics of common military aviation fuels
- JP-4 (NATO Code F-40)
- Highly volatile with a low flashpoint (-35 F)
- Compared to JP-5:
- easier starting
- lower operating temperatures
- slower acceleration
- higher tendency to vapor lock
- shorter range
- JP-5 (NATO Code F-44)
- Navy, Marine, and Coast Guard primary jet fuel.
- Similar to JP-4, except much more thermally stable
- Low volatility and has a flash point of 140 F
- Meets shipboard safety requirements.
- JP-8 (NATO Code F-34)
- Similar to JP-5.
- Better handling and operational safety than JP-4.
- Flashpoint is 100 F, which is lower than shipboard safety standards.
- Used by the Air Force.
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DESCRIBE a basic aircraft fuel system
 - Must supply clean fuel, free from vapor, at the proper pressures and flow rates to the engine under all operating conditions.
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DESCRIBE rated thrust
The max temperature of the turbine allowed without causing damage to the turbine.
- Normal Rated Thrust
- Thrust produced at the maximum continuous turbine temperature with no limitation.
- Serves for cruising speed.
- Military Rated Thrust
- Thrust produced at the maximum turbine temperature for a limited time; normally 30 minutes.
- Higher than NRT but time constraint ensures blades aren't damaged.
- Serves for takeoff or when additional thrust is desired.
- Combat Rated Thrust
- Thrust produced with the afterburner in operation, and is not based on turbine temperature limitations.
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