The Internet Museum of World War 2 Aviation
The best way to train a pilot is to have him fly a real airplane until he is proficient - right? So why not train aerial gunners by letting them actually shoot at real planes? This was the concept behind one of the US Army Air Forces’ most unusual training programs in World War II, often referred to as Operation Pinball.
The organized training of aerial gunners, those who would man the turrets and guns of the medium and heavy bombers of the USAAF, did not begin until June 1941, when the first flexible gunnery school was established at Las Vegas, Nev. The site featured good flying weather plus lots of uninhabited land over which practice gunnery could be conducted. Over the next two and one-half years, aerial gunnery schools were also opened in Arizona at Kingman and Yuma, Texas at Harlingen and Laredo, and in Florida at Tyndall Field near Panama City and an instructors’ school at Buckingham Field, near Ft. Myers.
At all the schools, most of the early gunnery training was conducted using such makeshift devices as shotguns mounted on the back of moving platforms, or the more sophisticated gun camera and projection screen trainers, such as the Jam Handy and Waller trainers. Some of the best and most realistic training came using gun cameras to “fire” at attacking fighters from the actual gun positions of medium and heavy bombers - but scoring and correction of the student’s performance had to wait for the film to be processed after the flight.
One man responsible for the gunnery training aids used at Harlingen in 1942 was Major Cameron Fairchild, and he is credited with the idea of developing a non-lethal bullet that could be fired at a real fighter without actually shooting it down. Initially, the idea was that the bullets could be made of glass, that would break apart and splinter upon hitting anything solid. To research ways to make a “frangible” bullet, Fairchild enlisted the help of two professors from Duke University, Paul Gross and Marcus Hobbs.
In the fall of 1942, Fairchild presented his idea to the National Defense Research Committee (NDRC) where the proposal ran into a brick wall - the Army’s Ordnance Department, responsible for the development of all weapons and ammunition. Ordnance argued that any bullet that was truly frangible would not have the same ballistic characteristics as real ammunition and would not fire from normal machine guns. They also worried that if such a bullet were fired at a target aircraft, the plane and its pilot would need special armor and other protection. The results were that NDRC allowed research to continue but with limited funding and urgency.
With the support of the Bakelite Corporation and Duke University, Professors Gross and Hobbs finally developed a .30 caliber bullet made of lead and bakelite (an early plastic) which could be fired from a slightly modified machine gun. The bullet did not damage heavy aluminium panels from ranges as close as 30-40 feet. By early 1944, a workable frangible bullet was ready for production under the designation T-44.
With the ammunition and gun problem solved, focus now turned to finding a suitable aircraft target. Initial tests had been performed against a Douglas A-20 twin-engine attack bomber, which had been fitted with aluminium armor in its nose and other exposed areas. However, a single engine fighter, preferably with a liquid cooled engine, would more closely resemble the German Messerschmitt 109 fighter, so often encountered by American gunners over Europe. The only high performance modern American fighter that was not in demand for combat use by US forces was Bell’s P-63 Kingcobra, most of which were being provided to the Soviet Union under Lend-Lease.
In August 1944, Bell modified five P-63A airframes, removing all armament, replacing much of the forward aluminium panels with thicker, armored panels and installing armored glass in the wind screen and side windows. In addition, over 100 microphones were installed behind the armored panels and rigged to indicate hits on a counter in the cockpit. A red light replaced the muzzle of the 37mm cannon in the propeller spinner and was to flash every time the plane was hit by a frangible bullet. Officially designated RP-63As (restricted from combat use), the five prototypes quickly became known as “Pinballs” and one had this name painted boldly on its nose.
After a few weight and balance problems had been worked out, a further 95 RP-63As were ordered, followed by 200 RP-69Cs in early 1945. With the first deliveries of mass produced frangible ammunition and Pinball aircraft, training finally got underway in early 1945, and the AAF staged a public demonstration of the new program in March of that year. By April 1945, frangible bullet training was underway at all seven flexible gunnery schools.
Several problems marred the training, some as had been predicted by the Ordnance Department. Gun sights had to be recalibrated for the lesser velocity and different trajectory of the frangible bullets, and the lead and plastic bullets caused the guns to jam more than usual. Worse for the pilots of Pinballs were the occasional real round of ammunition that got mixed in with the practise rounds. One pilot returned with his 38mm armored windscreen cracked, and it was agreed that no plastic bullet could do that.
But the frangible bullets did occasionally down a target plane, when the gunners continued firing when the Pinballs peeled off to start another attack run. This allowed fragments of the bullets to hit the oil and coolant radiators mounted in the wing roots, quickly causing the Pinballs engines to overheat. Thankfully, such “kills” ended in a safe gear-down landing in the desert.
To better protect the target plane and pilot, the last version of the Pinball, the RP-63G, had armor extended back to protect the engine cooling intakes - the total weight of armor reaching 2,164 pounds. In addition, more lights were added to the fuselage and wings to better indicate hits to the gunners. Only 32 of these ultimate Pinballs has been delivered when production cancelled at the end of the war.
With future fighters and bombers both jet powered and much faster, conventional aerial gunnery was about to become obsolete. The Boeing B-29s gun turrets were already remotely controlled, except for the tail gun, with electro-mechanical computers to aid in their aiming. Thus, the Pinballs and frangible bullet program were transferred to from the AAFs Training Command to the new Strategic Air Command, where they continued to help train B-29 gunners. By 1948, however, even SAC has abandoned the program. The surviving Pinball aircraft were redesignated the QF-63s just in time to be mothballed or scrapped.
If the frangible bullet program had been developed earlier, would it and Operation Pinball have saved American bomber crews over Europe in 1944? Many involved in the Pinball program think so, but with the end of the war came the end of the long heroic tradition of aerial gunnery, so we will never know for sure. One can only imagine that the Pinball pilots all breathed a collective sign of relief.