Here's an article from Flying about pusher props and quotes our aircraft.
http://www.flyingmag.com/technicalit...er-pusher.html
"............The poor performance of a Skymaster when its aft engine is shut down is due not to the inferiority of a tractor propeller but to flow separation on the extremely blunt aft end of the fuselage. When the rear propeller is powered, it draws in air around the aft end of the body, greatly reducing its drag, somewhat as turbulating dimples improve the performance of golf balls by shrinking the diameter of their wake. The Skymaster is a case in which the installed efficiency of the pusher propeller is indeed much greater than that of the tractor. But the effect cannot be generalized to other airplanes, because very few airplanes have fuselages shaped like the Skymaster's."