Japanese Navy 30mm aircraft guns

[genkideskan]

The japanese navy used Oerlikon guns. The 30mm Type 2 model 1 gun was a blown up 20mmType 99 model 2 system using a copy of the german MK 108 ammunition. Like the 20mm it was belt feed and used to fight the B 29 over Japan. The reason for this developement was to simply bring more explosive into the target. For the strong US bombers a 30mm projectile becomes nessessary.

Comparison of a 30mm Type 2 ( bottom) to 20mm Type 99

The 30 x 90 RB cartridge

Comparision to a german MK 108 round

Oerlikon guns couldnt be synchronised so the gun couldnt be used to fire through the propeller. Some where used in the Raiden fighter. I still look for more pictures, but the gun is hard to ID. Only the thicker barrel indicates a Type 2, some barrels are fluted. Here is a Raiden wing installation.The 30mm gun was installed beside a 20mm gun. May be someone has closer informations or some more fotos.

The Type 2 fired this 30 x 90 RB round using a 42 rd magazine or a beltfeed system. The gun weight was 51 kg and the length was about 2,00 meter. The projectile reached a velocity of 500m/sec and the rate of fire was about 380 rd/min. The gun was made at Dai Nippon Heiki Seisakusyo. Enclosed are some pages of the ammunition manual.

I read in an US report, that the Type 2 was used in wing mounts in Mitsubishi Zero fighters. At "least" 3 where wing armed with these guns in Rabaul in July 1943. That is very early I think. The weight for the 30mm gun was up to double the weight of a 20mm Type 2 and about three times the muzzle energy of a 20mm gun. That might be a problem for the aircraft designers to manage the recoil and drag forces.

Any information about the Type 2 are most welcome

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[genkideskan]

The "Type 5" 30mm gun is somewhat better documented. K. Huddle and T. Bradstreet examined a surviving gun in the USA and interviewed the inventor.
Ted send me a copy of the results 10 years ago.

Chief of the developement staff was Dr. Masaya Kawamura the designer of the after war Type 64 MG used by the JSDF. Dr. Kawamura developed a belt feed system for the 20mm Type 99 guns too. Even the US Bombing Survey singled it out as an "original and efficient gun". The Type 5 developement was
started in 1942 as the 17 shi Navy requirement and adopted in June 1945.
Barrel and receiver recoil as an unit sliding on a topcover.
The gun weight was only 70 kg - in that class the german MK 103 weights 140 Kg.
In a MOD Pattern room report Dr. Kawamura states that 3000 guns where made. The use in Raiden fighters is known - a wing mount with long outboard gun barrel fairings.

Raiden wing mount

The Type 5 ammunition was a 30 x 122 cartridge. A belt feed system was used.

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[genkideskan]

The gun examined by Bradstreet and Huddle has the serial number 1724 made by Toyokawa Naval Arsenal. The limited ammunition supply of the Type 2, a major reason for the navy to cease production, was solved with a belt feed system. No surviving belt links are known, but they might resemble the hook and eye type of the Type 99.
The Type 5 was planed as nose weapons of the Kyushu J7W1 Shinden fighter.
The foto shows dummys to give weight for the test flights.





The A7M2-3 Reppu Kai has thicker wings than the Zero and M2 Reppu and might be designed for in-wing T 5's.
Upward installations are known from P1Y2-S Kyokko ( Frances) and C6N1-S Saiun (Myrt) aircrafts. Both of these have Y0D tail codes. The Myrt installation is a known field installation completed in June 1945 and flow in hugh altitude patrols by Hiroshi Yasuda and Taro Fukuda.







A Raiden with the gun fairings was transported to the USA - the foto still showes the clamp fixed ruders.



Annother plane armed with the Type 5 gun was the P1Y2 Kyokko Frances. Armed with 20mm guns in the nightfighter role this aircraft was equipped with the 30mm gun too. Only minor modification was nessessary. Note the same tailcode as the Myrt. YO-D.





This unit was attached to defence the Tokyo aerea.

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[timshatz]

Great stuff Genk, very interesting.