The most common and most likely answer to this crossword clue is the 12 letter word AERODYNAMICS
I've seen this crossword clue in The Sunday Telegraph
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More clues leading to the result AERODYNAMICS
Buddy explains!
The straight part
We know that "properties of flying objects" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case properties of flying objects = aerodynamics.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does AERODYNAMICS mean?
AERODYNAMICS noun- The science of the dynamics of bodies moving relative to gases, especially the interaction of moving objects with the atmosphere
- The aerodynamic properties of a particular object (typically a car)