ASCI 309 – Field Exercise 2.2 Standard Atmosphere
ASCI 309 Standard Atmosphere – Airspeed Exercise
Part 1 Exercise Guidelines
Show all work, Highlight your Answers and use English units (Be sure to round to the 4th decimal point for #5-7, so .9612 instead of .96)
Name of your selected airfield: Raleigh- Durham International Airport, North Carolina and include the following:
ICAO identifier (the ICAO identifier is the 4-letter airport code, starting with a ‘K’ for the continental US):
KRDU
Field elevation [ft MSL]: 435 ft Surveyed
(field elevation can be found in the location information section at skyvector.com or the overview section at AOPA’s Airport Directory https://www.aopa.org/destinations/)
Current weather report at the time of work on this assignment to include:
Date and time: April 2, 2022 2:19 PM
Current altimeter setting [in Hg]: 30.10 in Hg
Current temperature [°F or °C, but stay consistent]: 60 °F
Using your researched data, find the Pressure Altitude of your airfield [ft].
Use the found altimeter setting and the rule of thumb lapse rate of 1 in Hg = 1000 ft, i.e. 00.01 in Hg = 10 ft change from the field elevation, with standard atmospheric altimeter setting being 29.92 in Hg (see also tutorial and example problems).
Based on your determined pressure altitude, find the Pressure Ratio, (delta), in the Standard Atmosphere Table (“Flight Theory and Aerodynamics”, Table 2.1 – the formula will not work, you must use Table 2.1). Interpolate as necessary.
Using your researched current temperature and the known standard sea-level temperature, determine the Temperature Ratio, (theta).
From your #5 and #6 results, find the Density Ratio, (sigma).
With your result, from #7, e-enter the Standard Atmosphere Table (“Flight Theory and Aerodynamics”, Table 2.1) to find the corresponding Density Altitude. Interpolate as necessary.
Screenshot and paste your Density Altitude Calculator twice, the first when set to 0% humidity and the second when set to 100% humidity.
Find Density Altitude [ft] with 0% relative humidity:
Find Density Altitude [ft] with 100% relative humidity:
Compare your findings I) and II). Describe what effects humidity has on Air Density:
ASCI 309 2.2 Standard Atmosphere – Airspeed Exercise
Part 2 Appendix B
Show all work and Highlight your Answers
Find the Calibrated Lift-Off Speed [KCAS] for 150 KIAS using the chart below, which is a typical example of an aircraft position error correction chart. (Consider that the gear would obviously still be in the down position at lift-off, so use the Landing Configuration Line).
Find the Equivalent Lift-Off Speed [KEAS] using your Calibrated Airspeed from #1 above and the Pressure Altitude for your selected airfield (from A). (Compressibility Correction Chart see “Flight Theory and Aerodynamics,” Fig 2.10). Comment on your findings. Why was/wasn’t the Compressibility Effect in your case negligible?
Find the True Lift-Off Speed [KTAS] (use the Density Ratio in question #7 of the Airspeed Exercise Part 1 document).
Calculate the Dynamic Pressure ‘q’ [lb/ft2], based on the TAS above. (Dynamic Pressure definition and formula can be reviewed in “Flight Theory and Aerodynamics” page 22 (EQ 2.1); make sure to use a formula consistent with a Lift-Off Speed in kts.
