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Old Sep 15, 2002, 06:24 PM
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Wiltshire England
Joined Feb 2001
924 Posts
A requirement for flying smooth, precision aerobatics is to have a model with the same pitch trim upright or inverted. If you have an airfoil with anything other than a symmetrical section this is very dificult to achieve.

The drag in inverted flight is high because the model has to fly nose up to generate the required lift and if you push into an outside loop the drag rises very rapidly. If you push too hard you will stall the wing easily which could in turn lead to a flick roll. Not nice!

This is not just theory but based on my own experience and that of a couple of my flying buddies with a supposedly aerobatic model with a typical "electric" cambered section. Eventually it caught us all out. I built a new version of the model with a symmetrical section. Hey presto a smooth neutrally trimmed pussy cat to fly.

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