Although designed to a 1939 requirement,
at a time when Japanese war
leaders scarcely imagined a situation
requiring a home defence fighter, the
Mitsubishi J2M Raiden (thunderbolt)
only came into its own while defending
the Japanese homeland against American
raids in the last year of the war.
The Japanese navy's emphasis upon
speed and climb rate, rather than its
customary demands for range and
manoeuvrability, prompted the designer
Jiro Hinkoshi to adopt a squat single-
engine design with long-chord radial
engine cowling, laminar-flow
wings and high-raked, curved windscreen.
First flight of the prototype
J2M1 took place on 20 March 1942, but
the aircraft soon attracted criticism
from navy pilots on numerous counts,
not least that the view from the cockpit
was inadequate. Modifications to rectify
these shortcomings were delayed
owing to Mitsubishi's preoccupation
with the A6M. Production J2M2 fighters
left the factory slowly and entered service
with the 381st Kokutai late in 1943,
and were followed by the J2M3 with a
stronger wing stressed to mount four
20-mm cannon. The heavier armament
now restricted the performance of the
Raiden to the extent that it no longer
met the original demands, and the
J2M4 was an attempt to restore the performance
by including a turbocharger.
The final production variant, the J2M5
(34 built), was powered by a 1357kW Mitsubishi Kasei 26a radial.
In all, 476 J2Ms were built. In acknowledgement
of the fact that J2Ms could
not combat the Boeing B-29s at their
operating altitudes, some J2M3s were
armed with two upward-firing 20mm
cannon in addition to their wing guns.
(The Allies selected the reporting
name 'Jack' for the J2M).
| ENGINE||1 x Mitsubishi "Kasei-23a", 1350kW|
| Take-off weight||3435 kg||7573 lb|
| Empty weight||2460 kg||5423 lb|
| Wingspan||10.8 m||35 ft 5 in|
| Length||9.95 m||33 ft 8 in|
| Height||3.95 m||13 ft 12 in|
| Wing area||20.05 m2||215.82 sq ft|
| Max. speed||580 km/h||360 mph|
| Ceiling||11700 m||38400 ft|
| Range||1900 km||1181 miles|
| ARMAMENT||4 x 20mm cannons, 120kg of bombs|
|A three-view drawing (752 x 1184)|
Although the MK4U-4 Kasei-26a engine of the J2M5 was more reliable than the engine in the failed J2M4, it was still prone to fail. Pilots wanted to trade them for J2M3s or even A6M5c Zeros! How unfortunate.
I thought the MK9 was reliable too, but wrong again.
The Type 5 30mm cannon was one of the best in class and armed a few Raidens. So they had 2x30s and 2x20s.
The type 5 was more reliable than the Army Ho-155 or short range German MK 108. The MK 103 is better but slower and weighs twice as much.
Some Russian sources say it's RoF was 500 rpm,
M/V was 760 m/s, 900m range. 345 gpr HE shell.
Awsome for tackling B-29s.
Others say RoF was 350-450 rpm and M/V 710-760 m/s.
Still the best compromise.
"stall with flaps down was 88 mph indicated. Speeds obtained at full load, less 1/3 fuel.
The ailerons are 8.85% of the wing area and have total deflection of 60° ( 33 up, 27 down ). Compare that with the Fw-190, with 10.55% and 34° total deflection ( 17 each way ).
The J2M should roll very fast indeed, assuming the controls forces are low enough to obtain maximum deflection. They were said to be heavy at all operational speeds."
-J. Aircraft site
It also said stall was 100 mph clean.
I believe ailerons got too heavy at 325 mph in the US test flight.
I just read that the Jack was better at B-29 head-on attacks than the Ki 100.
I posted that the 2 earlier low velocity Type 99-I cannons were replaced on the J2M5. Even before that they were traded for the Type 99-II in under-wing gondolas on the J2m3a, making all 4 wing cannons with matching ballistics sooner than I thought. This means 21 J2M3a Model 21a Raidens plus the 34 or so J2M5a Model 33a Raidens had harmonized firepower. 260 J2M3 Model 21s had the mixed 20mm wing-cannon and the earlier 155 J2M2 Model 11 had only the 2 Type 99-II wing-cannons and twin light MGs in the cowl like the A6M3 Zero. I've seen higher numbers ovrall but these are the conservative production quantities not counting prototypes.
Out off all Japanese fighters the 'Jack' was judged by the USN as most effective against them.
Also it was the interceptor of choice for Japanese navy pilots against USAAF B-29 raids.
It inspired confidence with its stability as a gun platform and during stall turns. Its vertical performance was likewise top notch, even up to its ceiling relative to most all Japanese planes.
As an interceptor it lacked the range of its forbear but improved durability and punch, packing 4 cannons of 20-mm.
Though it hit its stride against heavy bombers, there were pilots who loved picking on Mustangs in the Raiden with consistent victories.
Even RAF test pilots were impressed with the Jack fighter, in particular the reliable J2M5.
It certainly made itself felt out of all proportion to its tiny numbers. Maybe that's why it is often overlooked as one of the best Japanese fighters of WW2.
|laura ewalt, 07.05.2012|
What is the height requirment for them to be able to fly this back in the day?
Thanks for the eye-opening info, Aaron.
Too bad the mid-air disintegration problem could not be successfully solved. It makes one wonder if they could of at least tried putting the engine on an underpowered A6M5 Zero to skirt that mystery. Think how much sooner the reliable Kasei-26a would have been developed. Of course they wouldn't even put a more powerful 1,560 hp Mitsubishi Kinsei 62 motor in the Zero until the A6M8 as the curtain came down. This belated change is what Horikoshi preferred from the beginning. But by now it needed to be brought up to 1945 performance, not 1943 or 4. It needed Kasei class grunt in A6M5 quantities. Perhaps the Raiden would've been ready when the -26a came on board sooner, or not. At least the Zero would have kept pace with the Bf 109 in power to the end. Come to think of it, I kind of think of the Jack as a Mitsubishi 109K in effect.
Just purchased official TAIC reports for over 60 Japanese WW2 aircraft. The following are performance figures for the J2M3 Jack 21 using war emergency power Speed/Climb: S.L.:359mph/4,835fpm..1,000m:374mph/4,940fpm..2,000m:380mph/4,650fpm..3,000m:382mph/4,270fpm..4,000m:403mph/4,320fpm..5,000m:415mph/4,350fpm..6,000m:410mph/3,760fpm..7,000m:409mph/3,700fpm..8,000m:394mph/2,440fpm..9,000m:383mph/1,850fpm..10,000m:368mph/1,150fpm..11,000m:349mph/600fpm.
The maximum war emergency output of the Kasei 23 engine is 1,940hp at around 4,000ft. The weight of the aircraft tested was 7,320 lbs. The following is time to climb from a standing start: 1,000m/.6min...2,000m/1.3min...3,000m/2.0min...4,000m/2.9min...5,000m/3.9min...6,000m/4.7min...20,000ft/5.0min...7,000m/6.0min...8,000m/7.7min...9,000m/9.4min...10,000m/12.0min.
I have read that some U.S pilots that encountered the Jack commented that once it went vertigal it would just shoot away from them.
|Inigachi Sadamanka, 08.08.2011|
Our flight leader traded the Demon for one of these. His father apparently had connections with a branch of Nakajima firm that worked on the much better Thunderbolt. We were always jealous of his plane, unfortunatley it was lost in Februrary of 1945. If my damn website was still working, i could upload a still of him with it.
I have not had any luck so far finding any charts or documents on the J2M5. But I GOOGLED F6F-5 vs J2M3 and found a document titled FIGHTER COMBAT COMPARISONS No.1. comparing the two. It is a Tacitus Publications highly detailed computer analyses of the F6F-5 and J2M3. Very interesting read. The J2M3 with the Mitsubishi MK4R-A Model 23Ka engine has 1,940hp at war emergency. The following is at a Combat Weight: 7,184 lbs. Max. Speed: 380mph/19,685ft. Service Ceiling: 35,500ft (it does not state rate of climb at that height). Range: 655mls. Armament 2x20mm type 99 Mk.I and 2x20mm type 99 Mk.II. The Raiden outrolls, outturns out acxelerates and outclimbs the Hellcat up to 300-340mph depending on altitude. It list the maximum climb of the J2M3 as about 4,625fpm.
I would be surprised if most of those 34 were not in action before the end!
I think the top Raiden leaders flew the J2M5 if I'm not mistaken.
"The US Flight Test folks evealuating the Frank after the war squeezed 2,000hp out of the Homare and had the plane flying at 427mph! I sure wish all those tests were available for plane nuts to read now."
You got to remember the data from these tests were under ideal conditions for both maintenance and better quality aviation fuel. The supercharger on the production models and the gasoline that was available for the Ki-84 kept its speed around 392 mph (on a new machine) and this was from information given after the war from its pilots. When these tests were undertaken the superchargers had been worked on and improved and the higher octane US aviation fuel was used. So this is really nothing more than if only they could have done this. So fortunately for the allies planes like the Ki-84 never had the time or the necessary materials available to reach its full potential. The JM23 was a formidable plane especially in the hands of an experienced pilot and the J2M5 was an even better version, but alas only very few J2M5 were built (34), these few were spread out all over mainland Japan and very few of these made it into combat.
I forgot to put my two cents worth in on the best Japanese fighter of the war. Hmmmmmmm, I guess it all depends on what you consider what it takes to be "BEST". As far as I know the A6M was the only shipboard rigged fighter in 1942-1945 by the Japanese. So it would automatically be BEST SHIPBOARD FIGHTER. It is very hard to single one A/C out as being best. Numbers on paper do not tell the whole story. BUT, "if" we were to agree on A/C only in perfect condition and flown by expert pilots, we would still have to decide when (date) and where (altitude, distance/range). Again BUT, if I had to pick one over the other I believe the Ki.84 (in excellent condition) had the best overall performance coupled with the greatest potential for improvement. The contenders are J2M5, Ki.100-11 and N1K2-J. I may have mist one or two others though.
Confidential report titled COMPARATIVE PERFORMANCE AND CHARACTERISTICS REPRESENTATIVE ENEMY AND ALLIED AIRCRAFT page listing JAP FIGHTERS lists 9 Japanese fighter aircraft. The JACK 11, Mitsubishi is listed with the following performance and characteristics (Prepair for a pleasant surprise Raiden lovers): Engine: Mitsubishi Kasei 23. 1875hp/S.L. 1560hp/17.900ft *1940hp/3,940ft at WEP. The engine has water-methenol injection. Range: 1127mls/156mph/295gallons of fuel. Test weight: 7080lbs.
At WEP the performance was found to be the following: Maximum Speed 350mph/S.L. 407mph/17,400ft. Climb: 4600fpm/S.L. 4080fpm/17,400ft. 10,000ft/2.6min. 20,000ft/5.6min. Service Ceiling: 39,600ft. WOW, that is with the Kasei 23 not 26 engine. No wonder this was the prefered mount of navy flyers that had to intercept B-29s. No information is listed on the confidential data sheet concerning the date or specifics of the tests of the nine Japanese fighters listed, but the Jack 11 is the only one listed with an asterisk designating specifically that WEP was used. Yea, I know, this is the only place to date that I have seen any J2M listed as being a 400mph fighter. I would really like to see this test report, and even more see a controlled test report on the J2M5 with the Kasei 26a engine. I have read several articles that have said the US test pilots were suprisingly please with the excellent handling qualities of the Raiden, right up to 325mph.
Ronald, thanks for the great information on the armament, rates of fire and muzzle velocities.
The Kasei 26a in the J2M5 proved reliable, improving on the J2M3. A late-war Japanese fighter design like that was rare indeed.
Another would be the Ki 100.
|Mike Dunne, 18.03.2010|
On the question about which was the best Japanese fighter of WWII....maybe I should clarify my previous post. The Ki 100 was the best ARMY fighter...if the excellent Ki 84 could have been built with more care and under better conditions, there'be no comparison!
The US Flight Test folks evealuating the Frank after the war squeezed 2,000hp out of the Homare and had the plane flying at 427mph! I sure wish all those tests were available for plane nuts to read now.
|Mick Dunne, 18.03.2010|
Best Japanese Aircraft of WWII was the Kawasaki Ki 100!
No doubt at all. Not only a good fighter but very easy to fly...very handy when your pilot training programme has become somewhat compromised!!!
Regardless of plane type, the kill ratios have more to do with the ratio of planes in the sky. Near the end of the war, it was common to see the japanese planes outnumbered by a huge margin which gives a large advantage to the side with the numerical advantage even if the equipment is near equal in performance. It was the winning tactic vs the japanese........that and boom and zoom.....which again favors the force with larger numbers.
Best Japanese fighter of WWll was the Reppu. Seven were made one flew at the very end of the war. Apparently it was an equal to the P-51
Do you have any comments about this aircraft ?