Originally Posted by
klhoard
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What surprised me, and now that I've had a few days to think about it - it shouldn't have, is the massive amount of turbulence caused by the canopy.
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The worst effect of all that turbulence is simply wasted energy. Energy that comes from your batteries or glow fuel. That's why modern airliners don't have canopies sticking up into the airstream . . . perhaps Boeing and Airbus possibly know something that our pattern plane designers don't?
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The second negative effect of all that turbulence is what it does to the control surfaces. All that turbulent (and thus randomized) air is hitting the vertical and horizontal stab, and is also affecting the rudder and elevator. Kinda like trying to steer a canoe down a whitewater rapids. However, you can see that the nose of the airplane doesn't hunt around at all, so I imagine that the top part of the vertical stab / rudder are still in smooth air and able to steer the airplane.
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So . . . . like wheel pants, what purpose does the canopy on a pattern airplane serve other than "It will look weird and you won't get good scores without it"?
There's no massive turbulence caused by the canopy, unless the canopy is very poorly designed which is not the case for the Allure. I've seen jets designed to fly at Mach 2 with less streamlined canopies than those used on our pattern planes. If there's any turbulent flow, it's mostly caused by the spinning propeller and not by the canopy.
I think the tufts in the videos are way too long and may give you the wrong impression about the amount of turbulent airflow around the plane.
You can try moving the tufts elsewhere on the airframe and if you keep the same length i'm pretty sure you will get the same results. It doesn't mean the canopy or other parts are causing turbulence.
If the tufts are short, they will align themselves with the local airflow without shaking too much:
If there's any turbulent airflow, the tufts will show it even if they are cut short :
