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→General: Add What were the standard sizes of ammunition used by aircraft during World War II? Entry
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Although the V-1710 had a four year headstart in design and testing, the Government funded Merlin benefited from the experienced Rolls-Royce development team. They had the engine ready and with it the Battle of Britain was won. At that point in time, the V-1710 had just gone into series production. Furthermore, Rolls-Royce was able to grow the capabilities of the engine with their masterful arrangement of superchargers and aftercooling to provide a compact two-stage engine that was able to establish air superiority over both Europe and Japan. Allison was able to match this performance, but was never able to get its most advanced engines into production combat aircraft during the war.<ref>{{cite book |last1=Whitney |first1=Daniel D. |title=Vee's for Victory! The Story of the Allison V-1710 Aircraft Engine, 1929-1948 |date=1998 |publisher=Schiffer Publishing |location=Atglen, Pennsylvania |pages=336–337}} The block quote above is actually just the final summary section for an entire chapter comparing the two engines. For a much more detailed comparison, see pages 316 through 388 in the source.</ref>}} | Although the V-1710 had a four year headstart in design and testing, the Government funded Merlin benefited from the experienced Rolls-Royce development team. They had the engine ready and with it the Battle of Britain was won. At that point in time, the V-1710 had just gone into series production. Furthermore, Rolls-Royce was able to grow the capabilities of the engine with their masterful arrangement of superchargers and aftercooling to provide a compact two-stage engine that was able to establish air superiority over both Europe and Japan. Allison was able to match this performance, but was never able to get its most advanced engines into production combat aircraft during the war.<ref>{{cite book |last1=Whitney |first1=Daniel D. |title=Vee's for Victory! The Story of the Allison V-1710 Aircraft Engine, 1929-1948 |date=1998 |publisher=Schiffer Publishing |location=Atglen, Pennsylvania |pages=336–337}} The block quote above is actually just the final summary section for an entire chapter comparing the two engines. For a much more detailed comparison, see pages 316 through 388 in the source.</ref>}} | ||
=== What were the standard sizes of ammunition used by aircraft during World War II? === | |||
While there are countless variations, almost all rounds using on aircraft during World War II came in one of eleven sizes. In order of increasing diameter, they are:{{efn|A few notes regarding inclusion criteria for this list: | |||
* European and Asian nations primarily measured their cartridges in metric millimeters. The United States, instead, used caliber, which is measured in inches. As the predominant system, the decision was made to use the former for ease of comparison. | |||
* Not all cartridges of the same diameter are the same length. However, for the sake of simplicity no distinction is made between them here. | |||
* Countries are only listed after if they used the round in large numbers. For example, the United States experimented with a .60 caliber machine gun called the T17, but it never left the prototype stage, so it isn’t included.<ref>{{cite book |last1=Chinn |first1=George M. |title=The Machine Gun |date=1951 |publisher=U.S. Government Printing Office |page=106 |chapter-url=http://www.ibiblio.org/hyperwar/USN/ref/MG/III/MG-V3.pdf |access-date=5 August 2024 |chapter=Volume III, Parts VIII and IX}}</ref> | |||
Finally, this list is adapted from a much more comprehensive one: {{cite web |last1=Gustin |first1=Emmanuel |last2=Williams |first2=Anthony G. |title=World War 2 Fighter Armament Effectiveness |url=http://www.quarryhs.co.uk/WW2guneffect.htm |website=Military Guns & Ammunition |access-date=5 August 2024 |date=August 2013}} For more information, see: {{cite web |last1=Gustin |first1=Emmanuel |title=Ammunition |url=http://flying-guns.com/flying-guns-ammunition |website=Flying Guns |access-date=5 August 2024}}}} | |||
* 7.62 mm (.30 cal) – American, British, Soviet | |||
* 7.7 mm – British, Italian, Japanese | |||
* 7.92 mm – German | |||
* 12.7 mm (.50 cal) – American, British, Italian, Soviet | |||
* 13 mm – German | |||
* 15 mm – German | |||
* 20 mm – American, British, Italian, German, Japanese, Soviet | |||
* 23 mm – Soviet | |||
* 30 mm – German, Soviet | |||
* 37 mm – American | |||
In the jump from 13 mm and 15 mm, there is an important change in the makeup of the projectile. Until that point, the weapons are machine guns with bullets – that is to say they are simply solid pieces of metal. However, above it they are autocannon with shells, which means they have a small internal explosive. | |||
Choosing the correct size of round was a balance. Smaller rounds had a higher rate of fire and higher muzzle velocities, but were less damaging. Larger rounds, the opposite. These characteristics influenced how each type were used. | |||
When attacking small, maneuverable aircraft the engagement window – the time one has to shoot at the enemy – is very short. Therefore, high rates of fire are preferred to put as many rounds in the air as possible to increase the chance of a hit. On the other hand, larger aircraft, such as multiengine level bombers, are slow and lumbering, but can absorb more damage due to their larger size. In this case, a heavier round is better, as it takes less hits to bring down an aircraft and the target will likely not attempt to dodge. | |||
In turn, as a result of the situations they faced, different countries favored different rounds. Britain discovered early on in the Battle of Britain that the rifle caliber 7.7 mm guns in their Spitfires and Hurricanes lacked the stopping power to be effective. As a result, they quickly added 20 mm autocannon to their new aircraft. Germany and Japan would come to the same realization as they found themselves under attack from Allied bombers later in the war. As their situation grew desperate, they increasingly focused on the development of heavy autocannon and by 1945 were fielding weapons of 30 mm. | |||
The United States, never at risk of a bomber attack and facing mainly other lighter aircraft, stuck with the .50 caliber throughout the war. Furthermore, when facing an enemy such as Japan, whose aircraft were comparatively lightly built, a larger round would have been overkill. | |||
Some countries, notably Germany and the Soviet Union, also developed guns for ground attack. {{efn|It is important to address two myths here. First, it is commonly claimed that the Soviets liked the P-39 because they used its 37 mm for ground attack. This is incorrect.<ref>{{cite book |last1=Loza |first1=Dmitry |translator-last1=Gebhardt |translator-first1=James F. |title=Attack of the Airacobras: Soviet Aces, American P-39s, and the Air War Against Germany |date=2002 |publisher=University Press of Kansas |location=Lawrence, Kansas |pages=15–16 |url=http://books.google.com/books?id=qupmAAAAMAAJ |access-date=5 August 2024}}</ref> Second, while aircraft could be very effective at destroying most ground vehicles, tanks were a notable exception.<ref>{{cite web |last1=Moran |first1=Nicholas |title=Common Myths About American Armor in WWII |url=http://www.youtube.com/watch?v=bNjp_4jY8pY |website=YouTube |access-date=5 August 2024 |date=25 May 2015}}</ref>}} | |||
The postwar era saw near universal worldwide adoption of autocannon and today almost all fighters have guns in the 20 mm to 30 mm range. | |||
== Airplane Design == | == Airplane Design == | ||