Chuffer Chadley
13th Jun 2007, 13:41
Hello!
Here's a little question that I haven't been able to find a satisfactory answer to so far...
Why does IAS (in my heavy turboprop) increase in cloud?
I've noticed this particularly when in the descent (at Vmo, yes, clacker, capt gets a beer). I understand the following to be true:
1) Humid air is less dense than dry air, and clouds are humid.
2) IAS is a function of density, increasing with increasing density.
3) Turbine thrust also increases with density.
4) Some high-performance jet aircraft (eg Sea Harrier) use(d?) water spray into the intake to increase power at critical phases of flight.
Remembering that I have observed IAS increase when entering a cloud, how do we reconcile the above point 1 with the others? It occurs to me that a cloud is humid (low density) air, with water droplets, so the density of the air+water needs to be considered. But I might be wrong about that.
Can anyone help with my conundrum?
Ta!
CC
Here's a little question that I haven't been able to find a satisfactory answer to so far...
Why does IAS (in my heavy turboprop) increase in cloud?
I've noticed this particularly when in the descent (at Vmo, yes, clacker, capt gets a beer). I understand the following to be true:
1) Humid air is less dense than dry air, and clouds are humid.
2) IAS is a function of density, increasing with increasing density.
3) Turbine thrust also increases with density.
4) Some high-performance jet aircraft (eg Sea Harrier) use(d?) water spray into the intake to increase power at critical phases of flight.
Remembering that I have observed IAS increase when entering a cloud, how do we reconcile the above point 1 with the others? It occurs to me that a cloud is humid (low density) air, with water droplets, so the density of the air+water needs to be considered. But I might be wrong about that.
Can anyone help with my conundrum?
Ta!
CC