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Old 04-14-2012, 02:16 PM   #69 (permalink)
aerohead
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Quote:
Originally Posted by CFECO View Post
"Based on the description the side wind force on the fins counter balance the weight of the front mounted engine when that is also encountering a side wind."
The 917 engine was "mid" mounted, right at the rear axle, so the fins probably helped stability greatly. 917=Fantastic machine.
If you were to spin a car like a top on a slippery surface like black ice,you'd notice that it appeared to revolve around a 'pole' as Earth does.
This 'polar' position would represent the longitudinal position of the car's center of gravity(CG) and the car's polar moment of inertia would pivot about this point.
If you were to balance a car on it's tail or nose,the vertical line passing the the longitudinal 'center' would define the car's actual C.G..
If you were to also direct a strong blast of air from the side of a car when on a turntable,when the car was so positioned that it neither spun from the nose,nor from the rear,but 'balanced',with no yawing at all,the position of the turntable's pivot shaft center would define the longitudinal location of the cars' Center of Pressure ( CP).
For aerodynamic stability the CP is kept behind the CG,then if a strong gust is encountered,the car will simply weather vane itself into the wind,and thereby cancel any yawing moment.
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