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I heard about some of these issues shown in this article. Just throwing in an interesting perspective.
Japan's Fatally Flawed Air Forces in World War II | History Net: Where History Comes Alive – World US History Online | From the World's Largest History Magazine Publisher
But then Japanese Army came with Ho-5 which was possibly best ww2 mass produced cannon.
The Type 99-2 was with good ballistics from the start, since it was using the 'intermediate powerful' cartridge, leagacy of the FFL. Unlike the 'low power' Type 99-1, that shared low power cartridge with FFF, along with Ikaria MG FF.
A fine cannon indeed. The contenders for the title might be the B-20, MG 151/20, plus the ones that can't fire synchronised, Hispano V and Type 99-5. Allied report on the Ho-5, that does not fit in this time line:
The US saga of their production Hispanos was a sad one, the British production were good and got better. The Hispano V fired faster than the Mk II, while being lighter and shorter. Ballistics was great, even with the Mk V with a bit lower MV.
Muzzle velocity of both Ho-5, MG 151/20 and B-20 (and ShVAK) was in the ballpark, from ~730 (Soviet) to 800 m/s (MG 151/20 firing M-geschoss), so the ballistics were just fine.
The B-20 was a featherweight, more than 10 kg lighter than the not heavy Ho-5. ShVAK and MG 151/20 were a somewhat heavier than the Ho-5, but were earlier available.
The main shortcoming of the Ho-5 was that it fired the ligthest shell - 79g, per T. WIlliams. Hispano fired almost twice the weight (130 g), the IJN 20 mm cannons were at 128 g.
It was 85 g for Type 2 HE shell, same was for Type 4 HEI shell and finally the Type 100 AP-T round had a weight of 113 g.
Minengeschosspatrone was something like 95 g, thus not much heavier in this case from Japanese rounds. Panzergranatpatrone 151 had a weight of 117 g according to wiki.
It is known that the degradation of quality of Ho-5 guns effected in reduced powder loads to compensate for shorter life of firing mechanism.
Thanks for the excerpts.
The M-geschoss was with much more HE content, and even on just 92 g it was a powerful round. The H-geschoss principle was copied from French and British post war. There was also 115 g HE for the MG 151/20. There are very good articles about ww2 weaponry in this forum, 'Wepon system tech' subforum.
IMO the Soviets didn't judge their 20mm shell (95 g) as powerful enough vs. German bombers, going with the 37 mm cannon vigorously already in 1942 (and 45 mm soon after), while trying to employ 23 mm in air-to-air combat, coming out finally with the 'mid power' 23 mm cartridge in 1945 and 'mid power' 37 mm cartridge in late 1940s.
Americans studied the vulnerability of their aircraft. In a USAAF study conducted late in the Pacific War it was reported that fire was involved in 59 % of the aircraft lost. Smoke was observed in an additional 13 %. In a US Navy study of 501 single engine aircraft damaged in air to air combat from September 1944 to August 1945 the most common form of damage was to the aircraft structure (215) but nearly 90 % of the aircraft suffering such damage returned to base. In contrast of 57 aircraft suffering damage to oil or fuel systems only 18 % survived. Strikes in the cockpit hitting the pilot or controls resulted in only about 25 % of the aircraft surviving. This was the second most common form of damage. Damage to the engine or hydraulic system resulted in losses about 60 % of the time but was less common. A variety of other forms of damage caused relatively few losses.
Data from the American studies suggest that, despite self-sealing fuel tanks and pilot armor, fuel tanks and the pilot remained the most vulnerable areas on American aircraft. The American studies also ten to confirm the Japanese report that American fuel tanks were vulnerable to Japanese incendiary fire. (...)
In the US Navy study about 38 % pf all aircraft receiving damage were lost. About 30 % of the aircraft damaged received damage to the most vulnerable areas and accounted for 63 % of the losses. In contrast only 19% of the single engine Japanese aircraft damaged in 1941 Hawaii operation were lost. At least some of the Japanese aircraft returning to their carriers in a damaged condition had received hits in the fuel tank or cockpit area. During the Midway operation Japanese aircraft also survived similar damage. Losses among aircraft of the Japanese navy's 25th Air Flotilla from April to November 1942 amounted to 30% of all aircraft damaged, less than the loss ratio of aircraft in the US Navy study covering late 1944 and 1945. About twice as many Japanese aircraft were damaged in air combat compared to anti-aircraft fore (US Navy study was limited to damage in air-to-air combat). This data suggests American aircraft may have been about as vulnerable to Japanese aircraft fire at the end of the war as Japanese aircraft had been to Allied fire at the beginning of the war. This in turn suggests that the lethality of aircraft armament and ammunition eventually kept pace with and outstripped aircraft defenses.
Looks like the Ho-5 was designed from the get go around the not so powerful cartridge. The correction to the T. Williams book 'Rapid fire' has this by Ted Bradstreet, take it for what is worth:
PAGE 174:
The 20x94 ammunition in the Ho-5 was not downrated in performance: it was designed for 750 m/s from the start.
From here.
It was mentioned here that Ki-61s were armed with either 4 HMGs or heavier. However - they were initially armed with 2 LMGs and 4 HMGs.
This article might be worth reading: link.