Quote:
Originally Posted by freebeard
Further to my point. The edge angles on the F-117 are equivalent to a 2v octahedron, the 6v version I showed is within percentage points of a smooth compound curve as the angles approach 180°.
I suggest there may be a drag minima somewhere in between, where the edges encourage reattachment of the airflow.
|
The box cavity performs according to this principle.The sharp trailing edge precipitate separation,but the trailing edge of the cavities step lies along the 'Template' line,if you will.This trailing edge allows reattachment and capture of a locked vortex which allows the inviscid outer flow to close,decelerating and building pressure to cut pressure drag.
We'd pay for the circulation of all the vorticity,but I suspect we'd see an overall drag reduction.
And we wouldn't have to do the compound curves which are the most difficult to pull off.
This would be a great graduate research project for scale testing at a university wind tunnel.