As an Army Air Force pilot during World War II, one could expect to take fire from time to time — but the bullets weren't always coming from Axis aircraft. Sometimes, it was your fellow servicemen and women taking the shots.

The Bell P-63 Kingcobra fighter, developed in 1942, never got much love from the American military, which had a preference for the legendary P-51 Mustang. Instead, over 2,400 Kingcobras ended up in Soviet control under Lend-Lease, a wartime program to provide American allies with gear to fight Germany and Japan. That doesn't mean the US didn't put the P-63 into service, though: it ordered a bunch as the RP-63 "Pinball," a substantially modified P-63 designed specifically to be fired upon for target practice. Though primitive drones did exist at that time, airmen and women needed to hone their skills firing at the full-scale Messerschmitts they'd be encountering over Europe, which is where the Pinball came in. And real, actual pilots were at the controls as they were taking fire.

The RP-63 had a couple unique features that kept its operators relatively safe. Roughly a ton of armor was added, the canopy was reinforced, and the would-be aces in hot pursuit were firing "frangible" bullets, a mixture of lead and plastic that would disintegrate on impact with the Pinball's thick plating. Special sensors located throughout the fuselage detected hits, triggering a light in the nose cone so pilots could tell when they scored. Inside the RP-63's cockpit, a counter kept track of the tally.