P-39 Airacobra and P-40 Warhawk/Kittyhawk

[ShindenKai]

Fontessa, excellent info as usual, thank you!

Interesting video showing German & Japanese 20mm Cannon damage, nearly identical.
https://www.youtube.com/watch?v=bdr4ngshWl8

Another showing U.S. vs Soviet usage of the P-39, Soviets used them VERY effectively and it was flown by all their top Aces. Soviets liked the P-39 better than the famous Spitfire.
https://www.youtube.com/watch?v=l_pziH3tI9o

[fontessa]

Fontessa, excellent info as usual, thank you!

I believe that the number of fighters shot down is more reasonable than the total number of shots down when comparing the superiority of fighters.

Interesting video showing German & Japanese 20mm Cannon damage, nearly identical.
https://www.youtube.com/watch?v=bdr4ngshWl8

Thanks for the very interesting video.
The Japanese 20mm cannon shown in the video is Navy Type99 mod2. Japanese Army Airforce used another type of 20 mm cannon. And do you know Tony Mod1C used German MG151/20 20mm cannon? See the bellow for the detailed explanation,

Another showing U.S. vs Soviet usage of the P-39, Soviets used them VERY effectively and it was flown by all their top Aces. Soviets liked the P-39 better than the famous Spitfire.
https://www.youtube.com/watch?v=l_pziH3tI9o

Only the United States could mass-produce 9,000 of the complex mechanisms, with the propeller driven by the engine in the rear of the cockpit via an extension shaft and gearbox. Germany had no chance of winning when 5,000 of these were given to the Soviets.

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IJAAF 20mm cannons
Oscar same generation as Zero was not equipped with 20mm cannons. As shown by this, IJAAF was significantly behind in putting 20mm cannons into practical use. When developing IJAAF's 20mm cannon, HO-5, IJAAF focused more on firing rate than bullet power. This means that the bullet is lighter, but the firing rate was faster, so the projectile weight per unit time became to the same. This also allowed the cannon to be shortened, so it was possible to be mounted on the nose. However, there was a risk that the propellers would definitely be destroyed should the launch synchronization mechanism fail. For the case of Tony, Tony Mod1D mounted 2 HO-5s on the nose with the its extension of 20 cm.
HO-5 was developed from HO-103 which was 12.7mm MG of IJAAF. IJAAF foolishly decided to prioritize the development of the HO-103. Around the time Tonys were dispatched to New Guinea, it was keenly aware of the lack of power in the HO-103. The equippng of HO-103 was not in time due to the stupid decision earlier. Therefore, IJA requested the supply of MG151/20 20mm cannons from Germany. However, Germany also needed them in large quantities, so the Air Force General Staff was reluctant to supply them. Ultimately, the political decision of Field Marshal Goering decided to supply 2,000 cannons and 1,000,000 rounds. These had to be transported to Japan by submarines in several batches. As expected it was difficult and the IJAAF was only able to obtain 800 cannons and 400,000 rounds. They were all used for Tony Mod1Cs. The MG151/20 20mm cannon was far superior to his Type99 Mod2. In particular, the pilots and maintenance personnel were astonished that it operated safely and reliably. Also, since the bullets had a delayed fuze, they would automatically detonate even if they missed their target, so they did not harm residents in urban areas. From this point of view Tony Mod1Cs were used in the air defense air regiments.

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fontessa

[ROLAND1369]

Just for information the image you posed labeled P 39 is the similar but later P 63 fighter, distinguishable by, with other things, the different vertical stabilizer.

[ShindenKai]

Fontessa, why didn't the IJAAF also use the IJNAF 20mm cannons? Was the infighting really that bad? I was under the impression that the Ho-103 12.7mm MG was essentially a copy of the M2 .50cal MG.

Turns out I'm wrong:

Ho-103 Quick Stats

Mass 23 kilograms (50.7 lb)
Length 1,267 mm (49.9 in)
Barrel length 800 mm (31 in)
Cartridge 12.7×81mmSR Breda
Action Recoil operation
Rate of fire 983 RPM
400 RPM (synchronized) <------THIS IS VERY BAD <-----<<< greater than 50% reduction!
Muzzle velocity 780 m/s (2,600 ft/s)
Feed system Belt 250 rounds

M2 .50cal Quick Stats

Mass 28 kg (62 lb) (AN/M2)
Length 1,429 mm (56.3 in) (AN/M2)
Barrel length 910 mm (35.8 in) (AN/M2)
Cartridge .50 BMG (12.7×99mm NATO)
Action Short recoil-operated
Rate of fire 750–850 rounds/min (AN/M2)
1,200–1,300 rounds/min (AN/M3)
Muzzle velocity 2,910 ft/s (890 m/s) for M33 ball
Effective firing range 1,800 m (2,000 yd)
Maximum firing range 7,400 m (8,100 yd)
Feed system Belt-fed (M2 or M9 links)

The P-39s you posted are actually P-63's, the upgraded version. Taller-tail + engine & cockpit have been pushed forward to counter-act rearward CG shift when the ammo from the nose guns had been depleted. Oh and it also has a 4-blade prop, instead of 3.

[fontessa]

Hello ROLAND1369 and Shindenkaip

Thanks for the corrections.
It's my fault.

Fontessa, why didn't the IJAAF also use the IJNAF 20mm cannons? Was the infighting really that bad? I was under the impression that the Ho-103 12.7mm MG was essentially a copy of the M2 .50cal MG.

Turns out I'm wrong:

Ho-103 Quick Stats

Mass 23 kilograms (50.7 lb)
Length 1,267 mm (49.9 in)
Barrel length 800 mm (31 in)
Cartridge 12.7×81mmSR Breda
Action Recoil operation
Rate of fire 983 RPM
400 RPM (synchronized) <------THIS IS VERY BAD <-----<<< greater than 50% reduction!
Muzzle velocity 780 m/s (2,600 ft/s)
Feed system Belt 250 rounds

M2 .50cal Quick Stats

Mass 28 kg (62 lb) (AN/M2)
Length 1,429 mm (56.3 in) (AN/M2)
Barrel length 910 mm (35.8 in) (AN/M2)
Cartridge .50 BMG (12.7×99mm NATO)
Action Short recoil-operated
Rate of fire 750–850 rounds/min (AN/M2)
1,200–1,300 rounds/min (AN/M3)
Muzzle velocity 2,910 ft/s (890 m/s) for M33 ball
Effective firing range 1,800 m (2,000 yd)
Maximum firing range 7,400 m (8,100 yd)
Feed system Belt-fed (M2 or M9 links)

Yes, HO-103 was the copy of M2.
What was "400 RPM (synchronized)"?

The answer to your question "why didn't the IJAAF also use the IJNAF 20mm cannons?" is, simply saying, IJAAF did not want to fall behind the IJNAF same as the licensed production of the DB601 engine. Both had pointlessly high pride. From your point of view, it was very silly. It was a behavior that poor country Japan should not do.


fontessa

[fontessa]

What was "400 RPM (synchronized)"?
fontessa

Did you mean the "effective firing rate reduction" due to propeller synchronization?
If so, it was not the problem of HO-103.

fontessa

[ShindenKai]

Well, as can be seen from the stats of the guns the Ho-103 is not an exact copy of the M2, its smaller in every way and fires a smaller cartridge.

Yes, the method of synchronization GREATLY reduced the effectiveness of the Ho-103.

The Type 3 13.2mm MG was closer to the M2

Mass 27.5 kilograms (60.6 lb)
Length 1,530 mm (60 in)
Barrel length 910 mm (36 in)
Cartridge 13.2×99mm Hotchkiss (52 g)
Action Short recoil-operated, rising block locked (browning)
Rate of fire 800 RPM
Muzzle velocity 790 m/s (2,600 ft/s)
Feed system Disintegrating Belt

[fontessa]

The Type 3 13.2mm MG was closer to the M2

Yes, Type 3 MG was a copy of the M2 same as HO-103. IJAAF modified the M2 to fire more bullets at the slightest opportunity during dogfights, but IJNAF does not appear to have had such an intention. I think the U.S., which shared the M2 with the Army and Navy, was more reasonable.

fontessa

[LineDoggie]

Well CBI stands for China, BURMA, India

[fontessa]

Rate of fire 983 RPM
400 RPM (synchronized) <------THIS IS VERY BAD <-----<<< greater than 50% reduction!

400RPM was the setting value of a propeller synchronization device.
The 1st picture shows a propeller synchronization device 海軍95式同期発射装置 Navy Type95 Synchronized Firing Device. This was for 7.7mm MG, and it is said that the mechanism for IJNAF propeller synchronization device was the same. The trigger pull was activated only when the rotating red circle protrusion reached the red line. The rotation of the red circle was decelerated by the setting of the reduction ratio from the rotation of the engine. It probably hasn't changed since Fokker's days. The appropriate reduction ratio fluctuated according to the change in G applied during turning, so the reduction ratio should have been set low with enough margin.
The 2nd picture shows the instruction to change the synchronizing device from the device for 四翔 4 propellers with 〇・五四減速 0.540 reduction ratio to the one for 三翔 3 propellers with 〇・六八四減速 0.684 reduction ratio for 火星発動機十三型 Mars Engines Model13.
The 3rd Figure shows the gun firing system for Fw190A-8. Some books show the same layout drawing with same original. But only the 3rd Figure clarified about propeller synchronization devices. If we believe this, MG131 was synchronized individually, and MG151/20s were synchronized by one synchronizing device. As expected from Germany, everything was electric. According to ** 佐貫亦男 Sanuki Matao, the firing rate of MG151/20 cannons was reduced to 200RPM (~ 0.650 reduction ratio). Looking at above numbers, HO-103’s reduction ratio of ~ 0.5 Shindenkai shown seems not unnatural.
Shindenkai, can you show the source of "400 RPM (synchronized)".

** 佐貫亦男 Sagawa Matao was a propeller engineer. He stayed Berlin from April 1941 to November 1943, in order to purchase propeller technology. In his book written after the war, he says that in December 1943, on his way back to Japan on the Trans-Siberian Railway, he stopped at the Novosibirsk station and saw P-39s being assembled. When he approached to take a closer look, he was chased away by a burly female soldier carrying a rifle. (Appointed as Professor, Department of Aeronautics, Faculty of Engineering, University of Tokyo in 1958.)

海軍95式同期発射装置.jpg (78.21 KiB) Viewed 614 times

同期発射装置減速比変更.jpg (108.56 KiB) Viewed 614 times

fontessa

[LineDoggie]

I think you Americans can't accept that Japanese fighter plots didn't think the P-38 was a not formidable fighter. So I think we have to eliminate anything other than the shot down of fighters from the kill score.

Solve this real simple

How many Japanese Aircraft did the P-38 shoot down(1,857) versus how many Allied aircraft did the A6M series shoot down?

[fontessa]

I think you Americans can't accept that Japanese fighter plots didn't think the P-38 was a not formidable fighter. So I think we have to eliminate anything other than the shot down of fighters from the kill score.

Solve this real simple

How many Japanese Aircraft did the P-38 shoot down(1,857) versus how many Allied aircraft did the A6M series shoot down?

Sorry, I can't catch your point. Are you judging "which was stronger, the P-38 or the Zero" by "how many they were shot down in total?"

fontessa

[ShindenKai]

If we believe this, MG131 was synchronized individually, and MG151/20s were synchronized by one synchronizing device. As expected from Germany, everything was electric. According to ** 佐貫亦男 Sanuki Matao, the firing rate of MG151/20 cannons was reduced to 200RPM (~ 0.650 reduction ratio). Looking at above numbers, HO-103’s reduction ratio of ~ 0.5 Shindenkai shown seems not unnatural.
Shindenkai, can you show the source of "400 RPM (synchronized)".

Hey Fontessa, I simply used the quickest available source Wikipedia https://en.wikipedia.org/wiki/Ho-103_machine_gun

-I know its not generally considered to be the best source, but it does also list the sources supposedly used for that info.

So, the MG 151/20's were reduced to only 200rpm while synchronized OR reduced by 200rpm?

I must say I hadn't realized synchronization reduced the RPM so greatly, but it does make sense. But with that great of a reduction it would make more sense to simply move all the synchronized guns outside of the propeller arc, for maximum effectiveness.

Thank you very much again for the great info Fontessa! Its very interesting learning that there was some adjustability to the synchronization rate.

[ShindenKai]

I think you Americans can't accept that Japanese fighter plots didn't think the P-38 was a not formidable fighter. So I think we have to eliminate anything other than the shot down of fighters from the kill score.

Solve this real simple

How many Japanese Aircraft did the P-38 shoot down(1,857) versus how many Allied aircraft did the A6M series shoot down?

Is that ONLY aerial kills or does it include ground kills? How many of those kills are actually other Japanese fighters?? I don't know the total of aircraft shot down by the Zero, offhand. IIRC, in the early stages of the war the Zero had a kill/loss ratio of 12:1. After which the Corsair 17:1 & Hellcat 19:1, trounced them soundly (many reasons for this). BUT then again the Finnish Brewster Buffalos achieved 32+:1 and the Finnish Fiat G.50 Freccia's achieved 33:1!

NONE of what you've said changes the FACT that Japanese pilots gave the Mezashi a light-hearted nickname because they didn't see it as a major threat. It really is that SIMPLE. Maybe you should try to "go back in time" and convince them otherwise. Better yet, try your hand at a sim, see how that goes for you.

[fontessa]

I simply used the quickest available source Wikipedia https://en.wikipedia.org/wiki/Ho-103_machine_gun

Oh, Japanese Wiki lacks “400 RPM (synchronized)” line. I don’t know the reason whoy.

So, the MG 151/20's were reduced to only 200rpm while synchronized OR reduced by 200rpm?

,
“reduced to 200rpm mwhile synchronized” is correct.

I must say I hadn't realized synchronization reduced the RPM so greatly, but it does make sense. But with that great of a reduction it would make more sense to simply move all the synchronized guns outside of the propeller arc, for maximum effectiveness.

I can understand your doubts. But there must have been a reason why it didn't happen. The figure below shows the trajectory of the Fw190A-8. It seems that it was adjusted so that they converge 800m ahead. For that reason, the outer canons ① and ⑭ had to turn considerably inward. Therefore, there is a high probability that this will not hit the target at considerable range. As I said somewhere before, Japan converged within 200m. So Such a situation would have been unlikely. On the other hand, the possibility of
⑰⑲ was low. Although ⑰ and ⑲ have a slower rate of fire, the "total or integrated or combined hit accuracy" that took into account trajectory may have been higher than ① and ⑭. This is just my guess. However, the Luftwaffe deliberately chose position ⑰ and ⑲. Again, there must have been solid grounds.

fontessa