Hi,
Would yous please help me with the following?
In summer an aerodrome’s Density Altitude is 4060 ft with ISA of +7°C.
In winter the same aerodrome’s DA is 3060 with ISA of +9 °C.
How do I decide which one is the ‘worst case’ season?
A detailed answer will help me to have some more knowledge. I am new to this course 🙂
Quick question - can you check for a typo - is the summer deviation intended to be +17 ?
Either way, the summer case is the more critical for performance as it results in the higher DH.
Engineering specialist in aircraft performance and weight control.
thank you for the answer 🙂
but how did you end-up getting +17?
DA = 4060 and I have rounded that to 4100 ft
so, 15 - (4.1*2) = 6.8 round that to +7. isn't it?
am I doing something wrong?????
There seems to be something wrong with the question (unless it's a 'trick' question).
The question gives two DENSITY HEIGHTS. Therefore the temperatures are irrelevant since temperature is already considered in determining density heights. DH 4060 is a worse case than DH 3060.
Note also that 'density height' and 'density altitude' are interchangeable terms.
My apologies - I misunderstood your first post to be referring to ISA deviations. Suggest you rework your calculations starting with pressure height rather than density height.
As to whence the 17 degrees - that was based on the above presumption.
Engineering specialist in aircraft performance and weight control.
