Instruments Flashcards
Dynamic pressure =
Dynamic pressure = total pressure - static = ½pV2
Total Air Temp (TAT) =
Total Air Temp (TAT) = SAT + dynamic heating/ram rise
(% ram rise measurement known as ‘recovery’)
TAT = SAT + TAS2/100
(TAS in mph: low speed approximation)
(kts = mph x 1.15)
Calculating ‘down’ from a measured TAT requires consideration of K-factor
SART = TAT/(1+0.2K x M2)
(temp in Kelvin)
IAS > TAS
Compressibility becomes significant above M0.4/300 kt I R E T
Compressibility corrections always bring TAS and CAS closer together. PI C D
CAS vs TAS
Dynamic pressure (~CAS) = ½pV2
CAS = √pTAS Increase temp > p decreases > TAS must increase (at constant CAS)
Mach vs LSS
LSS = 38.94 √T (Kelvin) (661kts at ISA)
M = TAS/LSS (LSS increases with increasing temp)
Mach Variation with Altitude
Every Child Takes Milk
Constant CAS > reduced OAT > M same!
(TAS and LSS decrease)
AI Turning Errors
90o: Pitch-up/bank under-reads
180o: Bank correct/maximum pitch-up
270o: Bank over-reads
Types of Gyro
R - T 1 Rate Turn Indicator (yaw)
E I A 2 Earth AI (pitch and roll)
S I x 2 Space (Null)
T - D 2 Tied DI (hdg and stabilised for bank)
1,2 above = degrees of freedom (axes)
Planes of freedom = axes + 1
ASI: blockages and leaks:
Blockages and leaks - static blockage makes ASI overread in the descent.
PUDSOD - Pitot (blocked, ASI) Underreads in Descent/Static (blocked, ASI) Overreads in Descent.
Northerly Turning Error
Acceleration/Deceleration (part of dip)
Northerly Turning Error (part of dip)
Compass card banks with aircraft > Z component exerts a turning force.
Turning errors are maximum when turning through north (compass lags) and south (leads). (No. of vowels) ^^ In the northern hemisphere.
Acceleration/Deceleration (part of dip)
In northern hemisphere, an east/west acceleration cause an apparent turn to the north.
ANDS (In southern hemisphere: SAND)
