Temperature

Question 1

temperature units

Answer 1

fareinheit
celsius
kelvin

conversion on CRP if needed

Question 2

temp measuring- bimetallic strip or coil

Answer 2

invar and brass
expand at different rates
small temp change causes large change in bend
reads against a scale

Question 3

temp measuring- resistance

Answer 3

change in resistance measured to infer the temperature of the material
using a thermistor provides a small range

Question 4

temp measuring- thermocouple

Answer 4

two metals in contact produce a voltage that is proportional to the temperature difference
hot and cold junction in series
broad operating range

Question 5

TAT probe

Answer 5

air flows past sensors
air changes sensors temp
sensors resistance changes 
uses electrical resistance of wire
reads TAT

reading affected by: icing(has anti ice heat on body not sensor), solar radiation(sensor mounted inside to avoid), boundary layer

pirated version: can read on ground, causes suction with pressurised air from apu and draws air in

Question 6

RAM air rise

Answer 6

change in temp due to speed
indicated temp less than actual
SAT + RAM rise = TAT

Question 7

recovery factor

Answer 7

extent measured temp differs from actual TAT depends on ram rise measured
proportion measured called recovery factor Kr
measured ram rise = ram rise x Kr

Question 8

total temp can be expressed by the formula

Answer 8

Tt = Ts(1 + 0.2M2)
Tt- total temp
Ts- static air temp
M- mach