This is from a 1930s publication cover. The article was about the soon to be launched French Navy SURCOUF the one and only submarine cruiser ever built. It was a monster and mounted two 8 inch cannons in a limited traverse turret in front. And a small hanger for a small observation float plane in the back. But look at the cover. It shows two turrets mounting three cannons each and three aircraft, including one twin engine float plane!