[aerohead]

If the extension is elongated along the streamlined 'template' contour,and a side curtain is extended downwards to close the underside gap,such that creates the 'K' truncation,no separated flow will exists 'above' the aft-body,and all low-pressure,base pressure will be acting longitudinally,behind the vehicle as a drogue effect,with zero lift.Streamline bodies are incapable of generating lift.