What an ominous sound! It’s probably one of the most imposing aircraft that’s ever been built.
One of the main design features of the B-36, that gave it that unique sound was the pusher props. Exhaust gases were blown back through the slipstream of the props.
Of course, those 6 P&W R4360s provided the volume.
As engine fires occurred with the USAF B-36’s radial engines, some crews humorously changed the aircraft’s slogan from “six turning, four burning” into “two turning, two burning, two smoking, two choking and two more unaccounted for”
This problem was exacerbated by the propellers’ pusher configuration, which increased carburetor icing. The design of the R-4360 engine tacitly assumed that it would be mounted in the conventional tractor configuration—propeller/air intake/28 cylinders/carburetor—with air flowing in that order. In this configuration, the carburetor is bathed in warmed air flowing past the engine, so it is unlikely to ice up. However, the R-4360 engines in the B-36 were mounted backwards, in the pusher configuration—air intake/carburetor/28 cylinders/propeller. The carburetor was now in front of the engine, so it could not benefit from engine heat.