Ram Air Temperature (RAT) is defined as ?
defined as the sum of the OAT (ambient Outside Air Temperature),
plus some of the ram temperature rise.
Whats a Temperature probe sensor recovery factor ?
Represents the amount of ram temperature rise indicated by the probe.
OAT temp = -50c sensory recovery factor of 0.8, Ram temp rise at a given Mach number is 30°C calculate RAT ?
OAT of -50°C + 0.8 (80%) of 30°C (24°C) = -26°C RAT
Total Air Temperature (TAT) ?
is the sum of the OAT (which is known sometimes as the True Outside Air
Temperature [TOT]) and the full theoretical ram temperature rise due to compressibility effects.
Calculate TAT if OAT is -50c and ram temp rise is 30c ?
OAT of -50°C + the full 30°C temperature rise = -20°C TAT
Standard temperature at FL110 (11000 ft) is ?
15°C at MSL - [11 x1.98°C] = -6.78°C)
the pressure rise also
causes the airspeed indicator (ASI) to ?
Over read at high speeds
EAS is simply ?
IAS corrected for compressibility error
In the B727 the corrections for instrument and position error are
less than 1 kt so for practical purposes,
in this aircraft IAS = ?
CAS
find EAS for an aircraft flying at 300 KCAS at FL300 ?
Enter the F factor table at 300 kt and FL300 and obtain the F Factor of 0.95.
Step 2
Multiply the IAS by the F factor to obtain EAS: 300 x .95 = 285 EAS.
For practical purposes, the Indicated Mach Number is the ?
True Mach Number TMN
The Formula used to compute the speed of sound in knots is ?
Mach 1.0 (in kt) = Square root of OAT in degrees K x 39 -1
To then compute the TAS for any Mach Number other than 1?
TAS = Square root of OAT in degrees K x 39 x M -1 (where M = Mach Number)
To convert the Celsius temperature to Kelvin, simply add ?
simply add 273 to the Celsius
temperature.
find the speed of sound at MSL in ISA: (15°C) ?
M1.0 = (15C + 273 K) = V288 K x 39 -1 = 661 kt
example, find the speed of sound at MSL in ISA: (15°C)
M1.0 = (15C + 273 K) = V288 K x 39 -1 = 661 kt
Similarly, Mach 0.80M at the same temperature = ?
V288 K x 39 x .8 -1 = 528 kt
Find the speed of sound at the tropopause in ISA: (-56°C) ?
M1.0 = (-56C + 273 K) = V217 K x 39 -1 = 574 kt
Find the speed of sound at the tropopause in ISA: (-56°C)
M1.0 = (-56C + 273 K) = V217 K x 39 -1
= 574 kt
Similarly, 0.80M at the same temperature = ?
V217 K x 39 x .8 -1 = 459 kt
find the TAS at 0.80M at FL310 at a temperature of ISA+10 ?
The OAT must be computed by applying the ISA variation to the ISA OAT at FL310 from page
3-106 of the B727 POH.
ISA OAT at FL310 is -46°C.
ISA+10 therefore will be a temperature of -36°C. convert the OAT to Kelvin. In this example -36°C = 237K (-36°C + 273) M0.8 = V237 K x 39 x .8 -1 = 479 kt
find the Mach Number at a TAS of 455 kt with an OAT of -50°C ?
Calculate the TAS for 1.00M at -50°C ({V223K [-50 + 273]} x 39 -1 = 581 kt).
2
Divide the TAS given of 455 by the TAS of 1.00M of 581 (455/581 = 0.783 M).
find the OAT at a TAS of 420 kt and a Mach Number of 0.70M ?
Calculate the TAS of 1.00M for 420 kt at 0.70M (420+1/0.7 = 600 kt). The 1kt accounts for the
overread error of the formula.
Divide the TAS of 600 kt by 39, then square the answer and subtract 273k to find the OAT
of -36°C (420+1/0.7 = [600 kt/39) squared - 273 = -35°C)
For example, refer to the B727 POH page 2-8. A B727 has a BRW of 72000 kg and a climb is to be made to
FL350. From the table it can be seen that with a BRW of 72000 kg the climb to FL350 will take 22 minutes
and cover 136 nm in nil wind (ANM) while consuming 2750 kg of fuel at a published TAS of 418 kt. The forecast wind 2/3 of the way up results in a headwind component for the climb of -30 kt.
Follow these steps to determine how many miles will be covered over the ground (GNM) ?
Divide the 136 ANM by the time interval (ETI) of 22 minutes and multiply by 60 to find climb
TAS. 136/22 x 60 = 371 kt (this is far less than the published figure which should be ignored)
Step 2
Add the wind component to the TAS to find the climb groundspeed. 371 + -30 = 341 GS
Step 3
Multiply the Groundspeed by the ETI and divide by 60 to find the GNM.
341 x 22/60 = 125 GNM
we need to look at how to choose a particular cruise level for a flight. The
B727 is designed to cruise at FL’s in the mid to low ?
300s i.e FL300-FL350
Will weather, winds or trip length effect what cruising level you pick in the exam ?
No