Airspeed

Question 1

The formula for true altitude is

Answer 1

• TA = Actual Temp (K) x Indicated altitude
ISA temperature (K)

Question 2

Mach Number formula

Answer 2

• M = TAS TAS = True air speed

LSS LSS = Local speed of sound (38.94 Temp (K))

Question 3

Explain airspeed errors

Answer 3

IAS → Position error → CAS → Compressibility error → EAS → Density error → TAS

Question 4

What errors does a Mach Meter NOT suffer from?

Answer 4

• Density error & Compressibility error.

Question 5

The two capsules in a Mach Meter are what?

Answer 5

• Airspeed

* Altitude calibration.

Question 6

MFS is

Answer 6

• Free stream Mach number – airflow unaffected by the aircraft

Question 7

Ml is

Answer 7

• Local Mach number – is the speed of air relative to the Local Speed of Sound measured at a point on the aircraft

Question 8

MCRIT is

Answer 8

• The lowest free stream Mach number at which mach 1 is reached on any part of the aircraft

Question 9

How does weight affect MCRIT?

Answer 9

• An increase in weight will reduce MCRIT.

Question 10

Drag divergence mach number

Answer 10

• The increase in drag associated with compressibility effect (110 – 115% of MCRIT)