Temperature

Question 1

What are the 2 types of temp probe?

Answer 1

Bimetallic - cheap and suitable for GA. Uses two metals with different expansion coefficients.

Resistence - much more accurate. suitable for commerical use. uses electrical resistence of nickel wire with responds to temp changes.

Question 2

OAT?

Answer 2

Outside Air temperature - temp of undisturbed flow.

Question 3

SAT?

Answer 3

Static Air Temp - ambient temperature of the flow

SAT generally = OAT but can change close to the aircraft and when flowing over the wing due to temperature changes caused by air velocity and pressure changes.

Question 4

TAT?

Answer 4

Total Air Temperature - the temp we are able to measure with our probe which includes ramrise.

Question 5

Ram Rise?

Answer 5

Ramrise is the additional temperature gained to our reading due to friction and adiabatic compression at the probe. the free stream kinetic energy is converted to heat.

Question 6

RAT

Answer 6

Ram Air Temperature. Abit less than TAT and more than SAT. Obtained by obsolete probes that can still be found on business jets.

Question 7

TAT to SAT formula?

Answer 7

SAT= TAT(1 +0.2 M2)

temp in kelvin

Question 8

What is a recovery factor (Kr)

Answer 8

A correction value used to calculate TAT as the sensor is unable to measure actual TAT. What we actually get is ITAT (due to functional inability to reduce airflow velocity to complete stagnation)

Therefore correction factor is used to compensate ITAT to achieve TAT and thus SAT

Question 9

what is the formula for ITAT?

Answer 9

ITAT= SAT(1 + 0.2 Kr M2)