The biggest fighter

[Chris21wen]

I've just read this:

'By 15 Aug the Japanese were more in evidence. Destroyers, cargo vessels, even light cruisers began to frequent the central Solomon Islands, and Gizo Island and Gizo Bay in the New Georgia Islands became favorite target areas for the 11th Bomb Group. Moreover, the tedium of the long searches was apt to be broken by engagements with the huge Japanese patrol aircraft, the four-engine Kawanishi H6K, Navy Type 97 Flying Boat (Mavis). These Goliaths were slower and less maneuverable than the B-17's; their 20-mm cannon were outranged by the .50-caliber (12.7 mm) machine guns. Invariably Colonel Saunders' pilots attempted to close with them. The first victim fell to the crew of Captain W. Y. Lucas when, after a 25-minute combat the Mavis, attempting to settle her damaged bulk on the sea, was blown up by the B-17's tall gunner. By 30 Sep the 11th Bomb Group had encountered 21 Mavis'; 5 were destroyed and 7 damaged.'

Is this the biggest fighter of WW2?

[denisonh]

Got to love the ingenuity of the American serviceman......

[Yamamoto]

That is shocking to hear that a 12.5 mm gun outranged a 20mm cannon. Everything I've read indicated that the 20mm cannons had a longer range. That's why they monuted 20mm cannons in the tail gun positions in most bombers (Including the B-29).

Yamamoto

[Subchaser]

Originally posted by Yamamoto
That is shocking to hear that a 12.5 mm gun outranged a 20mm cannon. Everything I've read indicated that the 20mm cannons had a longer range. That's why they monuted 20mm cannons in the tail gun positions in most bombers (Including the B-29).

Yamamoto

20” really had longer range, theoretical, but was less accurate weapon. 20” canons were mounting in tail positions on bombers because it was easier to place larger weapon there and effectively operate it.

Weapon Pen Range Accu Effe GV
20mm Type 99 Mod 2 | 3 | 2500 | 22 | 4 | 4 |
.5" M2 BMG | 2 | 2000 | 26 | 3 | 3 |

So, 20” shells travel farther than 12,5 bullets, but mg bullets have more chances to hit a target. Accuracy rules!

Luftwaffe Fw-190A-8/R8 Sturmbocks tactics clearly represent these aspects of ballistics. To bring death to B-17s via 30” MK103/108 “pneumatic hammers” they had to fire them from 60-80 meters distance, although these cannons had pretty long range.

[Subchaser]

I have found evidence of such air combats from japanese side. It was mentioned in "Saigo no Hikotei" (Last Flying Boat), Asahi Sonorama, ISBN4-257-17286-X.

J-aircraft

[crsutton]

Japanese 20mm had range but a very low muzzle velocity. Not very accurate at range and hard to hit moving targets. Plus a slow rate of fire. The rear 20mm gun in Bettys was not feared in rear attack by allied pilots. As long as they did not approch from a direct six rear angle, the 20mm gunners could not hit them.

Was also a problem for zero pilots in turning fights as the 20mms charted a different course than the rifle caliber mgs due to the much lower velocity.

All in all, not a very good aircraft weapon.

[Feinder]

"... the IJN 20mm had a low muzzle velocity."

Bingo.

In short, the Japanese 20mm cannons sucked. They were not even remotely comparable to their counterparts in the US, Britian, or Germany.

And a little extra notage...

US fighters were largely armed with 50cal MGs. They were rarely armed with 20mm cannons.

Likewise, the German planes were usually armed with 20mm cannons (often changed to 30mm cannons by '44 and '45), and 7.5mm (30cal) had been all but removed from Luftwaffe fighters.

Why?

Consider the mission of each airforce:

The Luftwaffe was tasked with knocking down American heavy bombers such as B-17s and B-24s. The 7.5mm MGs on pre-43 fighters, were all but useless against the heavy bombers. Conversely, the 20mm cannons could down them much more effectively. As the war entered '44, more and more Luftwaffe fighters were equipped with 30mm cannons, which were even more effective. The 20mm cannons however were -not- as effective against US fighters (not the primary target of the Luftwaffe anyways). The slower ROF of the 20mm cannons were fine at attacking the slower moving bombers, that were also constrained to keeping formation (not maneuvering). However, the slower ROF of the cannons meant it was considerably harder to hit the maneuvering Allied fighters.

On the other hand, the Allies were tasked with escorting the bombers, and shooting down those same fighters. The higher ROF and ball ammo (essentially AP) of the 50cals, were much better suited for fighter vs. fighter combat. Higher ROF meant you didn't have to be as accurate like you would with the 20mm. You didn't NEED the punch of the 20mm cannon vs the much smaller fighter. And while the 50cal could damage the airframe, fighter pilots more likely kill their opponent because they killed the enemy pilot outright or damaged the engine or fuel systems. All of these systems (including the pilot), were usu protected somewhat by armor, but the 50cal with it's high muzzle velocity proved to do an adaquate job at penetrating the armor.

The Japanese didn't fair so well. At the start of the war, their weapons technology was not on par with the Western powers. Yes their pilots and aircraft were very good, but the guns themselves were not as high a quality. As noted before, their 20mm cannon had a very inferior muzzle velocity, which meant that it had a shorter range, was less accurate, and and didn't hit as hard. Japanese aircraft designers also showed a failure to adapt to the USN designs after '42. Their fighters were still carrying 7.5mm MGs, and still relatively few 20mm cannons. Such defenciency meant that the Japanese had a VERY difficult time knocking down american bombers (B-17s, B-29s, B-24s, and even the 2e bombers like the B-25 and A-20s). The Japanese aircraft simply couldn't hit hard enough to knock down their targets. Also, with shorter ranged, less accurate guns, the Japanese pilots were forced to close to shorter range for a longer period of time with the American bombers (thus giving the crews of the bombers more opportunity to down their assailant).

-F-

[Yamamoto]

What has been said here about American and Japanese weapons makes sense based on those countries’ design philosophies.
The Japanese 20mm cannon packed quite a bang – if it hit. It had a lower accuracy and relied on a pilot with more skill. The Japanese always thought of their pilots as modern day Samurai. Remember, Japan had been in the middle ages just 60 years earlier.

The Americans used a weapon that didn’t take as much skill to use. Their philosophy is good if you think of pilots as “ordinary Joes”. In the long run, this is the better philosophy but the Japanese with their highly structured class system could not allow themselves to think like that until it was too late.

If I were an ace and tasked with taking down bombers and fighters I would prefer the 20mm. If I were Joe Genero (average) I’d prefer the easiest, most accurate weapon I could find.

Yamamoto