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Becoming a pilot

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flyboy123

i know its less and actually that question cam eup in my exam and i put less but i wanted to know why. Thanks for helping but how does the venturi form. Doesnt a venturi form where a tube becomes smaller at one point or somthing creating the same effect? I dont deny that the pressure is lower in the cockpit i just wondered why

Think of a venturi tube. That's a tube which narrows in circumference before expanding again. As you've correctly said, that thin point is where the air speeds up.

Now imagine a canopy on an unpressurised aircraft; it's like a "dome" shape, which is just like half a venturi tube. Therefore you still have a pressure change, in the same way you have a small pressure change over a wing surface.

The air is shifted by the canopy, and because it's not completely incompressible you get a venturi effect even if you only have half of a venturi tube.