Q1.
Using the POOLEYS CRP5
39000 ft is above the ISA tropopause so the ISA temperature will be –56.5 degrees Celsius. Adding +5 ISA deviation gives a temperature of –51.5 degrees Celsius.
In the airspeed window set -51.5 degrees against 39000 feet.
Against 200 knots CAS on the inner scale read off 388 knots TAS on the outer scale.
This is greater than 300 knots so we must apply compressibility correction.
Compressibility correction = (TAS / 100) – 3
Inserting the 388 knots TAS gives (388/100) – 3 = -0.88.
In the compressibility correction window move the pointer 0.88 units to the left.
Against 200 knots CAS on the inner scale read off 383 knots TAS on the outer scale.
Q2.
ISA temperature at 35000 feet = 15 (35 x 1.98) = -54.3 degrees Celsius.
Adding –12 temperature deviation gives –66.3 degrees Celsius.
Adding 273 to this converts it into 206.7 degrees kelvin
LSS = 38.94 x Square root of absolute temperature
So LSS = 38.94 x square root of 206.7 = 559.84 knots
Mach Number = TAS / LSS so TAS = Mach x LSS
So at M0.78 the TAS = 0.78 x 559.84 = 436.68 knots
Q3.
Mach Number = TAS / LSS so LSS = TAS / Mach
So at M0.83 if the TAS is 485 knots we have
LSS = 485 / 0.83 = 584.3 knots
LSS = 38.94 x Square root of absolute temperature
So Absolute temperature = (LSS /38.94) squared
Inserting the figures from above gives
Absolute temperature = (584.3 / 38.94) squared = 225.2 degrees Kelvin
Subtracting 273 converts this into –47.8 degrees Celsius.
ISA temperature at 30000 feet = 15 (30 x 1.98) = -44.4 degrees Celsius.
Temperature deviation = Actual temperature – ISA temperature
Inserting the figures above gives
Temperature deviation = ( -47.8 ) – ( -44.4 ) = +3.4 degrees Celsius.
The closest option is +2.
Q4.
A rate 1 turn takes 2 minutes to turn through 360 degrees.
Dividing 360 knots by 60 converts into 6 nm per minute.
So in 2 minutes the aircraft will fly 12 nm, which is the circumference of the circle.
Circumference = 2Pi x Radius
So Radius = Circumference / 2Pi
Dividing 12 nm by 2Pi gives a radius of 1.9098 nm.
The closest option is 2 nm.