With the airplane so far above its optimum altitude, although we had called in for a breakaway maneuver, I had already given up hope of completing this portion of the bomb run. I had planned to burn off fuel and/or request a lower altitude later. At simulated bomb release, I initiated a right turn to return to the pre-initial point for another bomb run. When I had 12 degrees of bank established in the turn, the airplane shuddered perceptibly. I knew the airplane was not happy and that I and my crew were in trouble. I immediately ceased increasing the bank. When I attempted to remove some of the bank, the B-47 said it had had enough of this and stalled. We were in an express elevator going down. The vertical speed instrument was pegged on the down side of the instrument, and the altimeter was unwinding rapidly. The heading indicator could not find a place to rest. It was dark, and the stars, so friendly seeming only moments before, were now rotating about my canopy. How many turns occurred in the spin? I have no idea. When we did spins in the T-6, we counted each turn. With the stars rapidly turning above me, I was more interested in stopping the rotation and getting back to level flight.