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How does the performance of a piston engine change with variations in air temperature?

  • A

    Higher temperature equals lower air density, which leads to lower engine performance.

  • B

    Lower temperature equals lower air density, which leads to higher engine performance.

  • C

    Higher temperature equals higher air density, which leads to higher engine performance.

  • D

    Lower temperature equals higher air density, which leads to lower engine performance.

A rise in air temperature causes a reduction in air density, due to the increased collisions between particles, keeping them further apart.

Reduced air density leads to a reduction in the amount of air particles flowing over an aircraft's wings, which leads to a reduction in ift. This means that an aircraft must fly faster to gain the same amount of airflow, to get the same amount of lift. this lengthens take-off distances as the aircraft has to reach a higher speed.

The engines are even more affected by temperature rises and density reduction. both piston and gas turbine engines produce higher power when the air is colder (and therefore denser), as there is more oxygen to burn alongside the fuel.

Gas turbine engines also become TGT (Turbine Gas Temperature) limited when temperatures get above a certain amount, and this leads to the engine having to reduce their thrust output to stop the turbine melting. Propellers are also affected in the same way as wings, by having reduced air, they produce less power.

Therefore, no matter what type of aircraft is being referenced, the power/thrust output will be reduced by the higher heat.

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