Highly technical aerodynamic question
Most of you would have observed that when taxying the cockpit is often buzzing with those pesky little bush flies. When the aircraft's cabin altitude climbs to around 5000 feet the flies seem to "go off to sleep" and disappear.
On descent as the cabin heads through the same approximate altitude, they wake up again to bother you.
Now my question is "Why?"I have 2 thoughts:
First, the flies become mildly hypoxic in the rarified air of about 5000 foot and above, and too lethargic to fly. This could be explained by the drop in partial pressure which is not enough to force the oxygen though their exoskeletons (they have no lungs). Less oxygen, less activity.
Secondly, the aerodynamics of a fly is so optimised that the increase in altitude no longer allows it to fly - the wings no longer
produce sufficient lift.
Any suggestions as to which one would be correct, or any other ideas? I have ruled out temperature as pressurised a/c can hold the same or warmer temps as ground level.
If there are no answers here, I might test out the theory in the back shed with a a glass jar, suction pump, altimeter, oxy level meeter, oxygen and nitrogen bottles.
And flies.
CS