Home | Articles | Links | Archives | About us | Contact

Into Friendly Fire: the RP-63 "Pinball"

by Gaëtan Marie

To man the turrets and guns of the thousands of American medium and heavy bombers in World War II, unprecedented numbers of gunners had to be recruited and trained. Gunnery schools were hastily set up all over the United States. Teaching students to master the very complicated art of aerial gunnery proved problematic. With time, techniques improved and culminated in 1945 with the introduction of the Bell RP-63 in what has become known as “Operation Pinball”.

The first flexible gunnery school was created in June 1941 near Las Vegas, Nevada. The location was ideal: good flying weather and vast uninhabited expanses allowed for intensive gunnery training. However, early training techniques were more or less improvised and not particularly effective. Among various training devices to be found were guns and turrets mounted on the back of moving trucks, skeet shooting ranges, projection screens and towed “sleeve” targets.

Shooting at towed targets was the most realistic training gunnery students would get during their 5-week training course. Each student was given 2,000 rounds of colour-tipped ammunition. A target-tow aircraft would formate with the aircraft carrying the students, who would take turns at firing at the target. Back on the ground, the target would be examined. Each impact left a colour mark that showed who was responsible for the hit.

This was the best training available but was far from perfect. As the tow aircraft flew a rather predictable course, it made for an easy target, considerably easier to hit than a maneuvering enemy fighter. Accidents were rare, but did happen from time to time. Several tow aircraft were shot down during training, and crews were wounded or killed.

At the end of the five week course, gunnery students were awarded the Aerial Gunner's badge (Drawing by G. Marie).

In 1942 and 1943, additional gunnery schools were opened in Arizona, at Kingman and Yuma, in Texas, at Harlingen and Laredo, and in Florida at Tyndall Field. A new technique was introduced, which would yield good results. Instead of firing guns at towed targets, students aimed cameras at real fighters. This allowed fighters to simulate realistic attacks on the bomber from different angles. After the mission, the camera film was developed. Instructors would analyse it to calculate scores and help students improve their skills. This was far more realistic and gave better results but also required more time.

Obviously, the best possible training would have been to fire real ammunition on real fighter aircraft. To do this, the only possible solution was to develop a type of ammunition which would not cause damage. A proposal for research on “frangible bullets” was made to the National Defence Research Committee in late 1942. The Army's Ordnance Department (A.O.D.) was quick to point out that a frangible bullet would not have the same ballistics as normal ones, and that they could not be fired from normal guns. The A.O.D. also pointed out that even a frangible bullet could cause damage, and that the target would need additional armour plating. Research on the frangible bullets was authorized, but was only given a limited budget and low priority.

Professors Gross and Hobbs began working on the program, with the support of Duke University and the Bakelite foundation. They developed a .30 calibre round with a compound lead and bakelite shell, which would disintegrate upon impact. The round could be fired from slightly modified Browning M2 guns, and was given the designation T-44.

Testing began with firing at heavy aluminium sheets. It was found that no major damage was inflicted down to ranges of 30 feet. The A.O.D. was proven right about their earlier assumptions concerning the whole program. While the bullets did have ballistics similar to those of live rounds, they were not quite identical. At 1,360 ft per second, the muzzle velocity of the “Duke” rounds, as they were sometimes called, was lower than that of the standard .50. As it was recoil-operated, the M2 machine gun needed gas assistance to keep working with this ammunition. Gunsights also had to be recalibrated. These modifications gave the .30 machine gun the same behaviour and “feel” as the .50 Browning M2, which was the standard defensive gun at the time. Gun jams were also more frequent with frangible rounds.


Next Page >