Temperature

Answer 1

~SAT: temp of the air around the a/c but anaffected by the passage of the a/c
~OAT: temp measured at a given point out of direct sun light

~TAT: temperature the a/c feels on the skin

Tat is greater than sat due to ramp rise in temperature occurs bc of the dynamic heating

Ram air temp rise is proportianl to the speed of the a/c

Answer 2

RAM RISE = TAT-SAT
RAM RISE = approx (TAS/100)SQUARED

Question 3

FOUR TEMP MEASURMENTS

Answer 3

~thermal expansion : (direct reading)

~electric resistance: wheatstone bridge circuit,basically a change in resistance of R2 will result in current flow being indicated in Vg as temperature which is proportional to temperature change

~elecritcal thermocouple: resistance of many materials changes with temperature,the calibrated change in resistance can be displayed as temp read out

~radiation (pyrometry): measures the radiation emitted to read the temp

Question 4

Thermal expansion

Answer 4

Bimetallic strips ,reads the difference in the two material (steel,brass)

Question 5

Electrical ressitar

Answer 5

Works on the principle on the chnage in material with temp
~changes in resistance of r2 will result in current flow being indicated in Vg as temp which is proportional to temperature

Question 6

Thermocouple

Answer 6

Different in cold and hot junction creates a voltage whihc indicated the temp

Question 7

Pyrometry

Answer 7

Infared measurement,the higher the radiation higher the temp

Question 8

Total air temp probe

Answer 8

Located pn the inner forward fusealge,forward of the wing and outside the boundary layer and outside direct sunlight on a stalk

Question 9

Tat probe

Answer 9

Is made of nickel plated beryllium copper
And there is a divergence docut pushes the air in the sensor
The air exit directly to avoid ice accreation
Linear resistance change to temp changes
Rapid response to temp changes
High rate of consuctuvity

Question 10

Tat probe erros

Answer 10

~ environment
~latent heat
~radioant heat sunlight
~heating errors
~friction heating

——
Bleed holes reduce compressive heating effects

Question 11

Aspirated tat probe

Answer 11

Aspiration tube ( from the engines)is used when the a/c is stationary to drive the air mass through the TAT PROBE

Question 12

Ram rise

Answer 12

Caused by adiabatic compression (heating) effect is the difference between SAT and TAT

Question 13

MEASURED RAM RISE

Answer 13

Ability of the probe to measure the amount of the ram rise depends upon its RECOVERY FACTOR (Kr) ,a vlaue set by the manufacturer and expressed as a decimal

~kr’s valiue will be given as a number less than 1
And is applied to the ram rise once ite sbeen established

Measured ram rise=ram rise X Kr

SAT= RAT- MEASURED RAM RISE