Quote:
Originally Posted by aerohead
... After reaching maximum cross-section,even with turbulent boundary layer,the flow cannot tolerate radical pressure gradients.
The aft-body has got to taper gently allowing flow deceleration for pressure recovery.Too steep,and it separates,and the base pressure will be the same as at the point of separation.
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NASA guy told me ~8 degrees was max slope on aft body, to avoid undue separation and turbulence. German sailplane research showed essentially that, as seen in oil smear tests in wind tunnel.