Quote:
Originally Posted by drmiller100
We must be talking about different things, and I would appreciate your patience in helping me understand what you are saying.
Where does Reynolds Number fit in with what you are saying?
Are you implying that all objects with all reynolds numbers all stall at about 22 degrees normal to the surface?
Surely that is not what you are saying????
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*The Reynolds number is related to a structures length and velocity.At a 'critical' velocity,the smoothest surface which can be manufactured will transition from a laminar boundary layer,to a turbulent boundary layer.
*A turbulent boundary layer cannot follow a slope which is steeper than 22-degrees without separation.This was determined on a 16.13% thickness fuselage.
*All structures which are moving at a velocity at,or above critical velocity are limited to the 22-degree slope angle in the aft-body.
*'Laminar' wings are 'laminar' only up to the position of minimum pressure and immediately transition to turbulent boundary layer.
*Wings are 2-dimensional flow devices and are different than the fuselage which is a 3-dimensional flow structure.
*All structures in 3-D flow will suffer flow separation if the aft-body convergence exceeds 22-degrees.
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*Automobiles,due to their size achieve a turbulent boundary layer at about 20 mph and from there on their drag coefficient is constant.
*Automobile drag is ruled by pressure drag,which is ruled by separated flow.
*To eliminate separation,the cars body is extended with curvelinear taper both in elevation and plan just as the 'Template' depicts.
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*Aircraft design virtually 'presumes' attached flow and skin friction and induced drag are the bogeymen of aircraft performance.
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I am saying not to go beyond 22-degrees on any car unless you can provide a 'blown' or 'suctioned' aft-body to stabilize the boundary layer.
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I'd say the same thing for a fuselage although their drag is of little consequence to the overall drag of a plane.
You can chop off the last 20% of a fuselage on an aircraft and it will never show on the fuel gauge.This is why the tails on the cargo planes matter very little to overall performance.