IIRC it was designed to be flown over german coloumns of supply trucks and horse and wagons. At 1,000 ft or so the danger from one pass is fairly minimal to the bomber but with 88 guns spitting lead out the effect on the road, vehicles and horses below looked somewhat like an organic pincushion.

BTW I think all the guns were linked to a common hopper holding enough ammo for 20 secs continuous fire. Since the PPSH was fairly resistant to jamming it worked ok.
BTW this is a shot of the test bed- the system looked different later.
[ 06-09-2001: Message edited by: Sorrow[S=A] ]