J2M Raiden Performance

[Laurelix]

J2M1:
Empty Weight: 2191kg
Loaded Weight: 2861kg
Wing Area: 20.05m2
Engine: MK4R-A Kasei 13
Take Off: 1430hp / 1400hp at 2700m / 1260hp at 6100m
-
Max Speed: (Military Power)
578km/h at 6000m
-
Rate of Climb: (Military Power)
Time to 6000m: ???
-
Turn Time:
16 seconds
-
Stall Speed: (At Sea Level, No Flaps)
149km/h IAS
-
Armament:
2x 7.7mm Type 97 (550 rounds per gun)
2x 20mm Type 99 Mk 2 (100 rounds per gun)

———————————————-

J2M2:
Empty Weight: 2348kg
Loaded Weight: 3210kg
Wing Area: 20.05m2
Engine: MK4R-A Kasei 23a
Take Off: 1820hp / 1575hp at 1800m / 1410hp at 4800m
-
Max Speed: (Military Power)
596km/h at 5450m
-
Rate of Climb: (Military Power)
Time to 6000m: 5:38
-
Turn Time:
17 seconds
-
Stall Speed: (At Sea Level, No Flaps)
157km/h IAS
-
Armament:
2x 7.7mm Type 97 (550 rounds per gun)
2x 20mm Type 99 Mk 2 (100 rounds per gun)

———————————————-

J2M3:
Empty Weight: 2490kg
Loaded Weight: 3440kg
Wing Area: 20.05m2
Engine: MK4R-A Kasei 23a
Take Off: 1820hp / 1575hp at 1800m / 1410hp at 4800m
-
Max Speed: (Military Power)
596km/h at 5450m
-
Rate of Climb: (Military Power)
Time to 6000m: 5:40
-
Turn Time:
18 Seconds
-
Stall Speed: (At Sea Level, No Flaps)
163km/h IAS
-
Armament:
2x 20mm Type 99 Mk 1 (190 rounds per gun)
2x 20mm Type 99 Mk 2 (210 rounds per gun)

———————————————-

J2M4:
Empty Weight: 2823kg
Loaded Weight: 3947kg
Wing Area: 20.05m2
Engine: MK4R-C Kasei 23c
Take Off: 1820hp / 1420hp at 9200m
-
Max Speed: (Military Power)
585km/h at 9200m
-
Rate of Climb: (Military Power)
Time to 10,000m: 19:30
-
Turn Time:
21 seconds
-
Stall Speed: (At Sea Level, No Flaps)
175km/h IAS
-
Armament:
2x 20mm Type 99 Mk 1 (190 rounds per gun)
2x 20mm Type 99 Mk 2 (150 rounds per gun)

———————————————-

J2M5:
Empty Weight: 2540kg
Loaded Weight: 3507kg
Wing Area: 20.05m2
Engine: MK4U-4 Kasei 26a
Take Off: 1820hp / 1510hp at 2800m / 1400hp at 6800m / 1310hp at 7200m
-
Max Speed: (Military Power)
615km/h at 6580m
-
Rate of Climb: (Military Power)
Time to 6000m: 6:20
Time to 8000m: 9:45
-
Turn Time:
19 Seconds
-
Stall Speed: (At Sea Level, No Flaps)
165km/h IAS
-
Armament:
2x 20mm Type 99 Mk 1 (190 rounds per gun)
2x 20mm Type 99 Mk 2 (210 rounds per gun)

———————————————-

J2M6:
Empty Weight: 2490kg
Loaded Weight: 3440kg
Wing Area: 20.05m2
Engine: MK4R-A Kasei 23a
Take Off: 1820hp / 1575hp at 1800m / 1410hp at 4800m
-
Max Speed: (Military Power)
590km/h at 5450m
-
Rate of Climb: (Military Power)
Time to 6000m: 5:40
-
Turn Time:
18 seconds
-
Stall Speed: (At Sea Level, No Flaps)
163km/h IAS
-
Armament:
2x 20mm Type 99 Mk 1 (190 rounds per gun)
2x 20mm Type 99 Mk 2 (210 rounds per gun)

Note:
Turn Time values are at 0-1000m, 360 sustained horizontal turn, No Flaps and at War Emergency Power. Turn Rate and stall speed value don't come from the sources. They are calculated by me. Etc Looking at J2M3, its turn rate should be pretty much identical to the Yak-3 (18 seconds) if they both do not use flaps. (Yak-3 has no combat flaps, the J2M3 does)

Sources:
• Mitsubishi Data, Jiro Horikoshi's book
• Specification and Performance of Service Airplanes of the IJN (10th September 1945)

 

[fubar57]

Not doubting you but a list of sources would be beneficial with these kinds of posts

 

[Laurelix]

Not doubting you but a list of sources would be beneficial with these kinds of posts

There you go

 

[gomwolf]

Here is J2M2 Model 11 specification on TAIC report.

 

[Laurelix]

View attachment 551273View attachment 551274View attachment 551275

Here is J2M2 Model 11 specification on TAIC report.

The US TAIC calculated the J2M performance. Its mega overoptimistic. Eventhough both J2M2 and J2M3 use the exact same engine, TAIC gives J2M2 655km/h and 671km/h to J2M3.

In reality J2M2/J2M3 had 596km/h at 5450m and 613km/h with WEP. They have extremely draggy airframes.

For those who dont believe TAIC uses calculated figures a lot, heres the Tony 2 TAIC Report.
http://www.wwiiaircraftperformance.org/japan/Ki-61-154B.pdf
At Sea Level they calculated 539km/h , which is very close considering it did 541km/h.
However they didnt capture this plane nor did they have full power curve of the engine.
So US intelligence stated this thing had 681km/h at 8500m. (based on a calculation using incorrect engine power curve)
Truth is the plane could only do 610km/h at 6000m at military and 620km/h at 5000m with WEP since it didnt have a supercharger which the US thought it did have.
It just proves TAIC does use calculated figures.

Ill trust the aircraft designer of J2M over calculated US TAIC report anyday.

 

[Ivan1GFP]

The US TAIC calculated the J2M performance. Its mega overoptimistic. Eventhough both J2M2 and J2M3 use the exact same engine, TAIC gives J2M2 655km/h and 671km/h to J2M3.

In reality J2M2/J2M3 had 596km/h at 5450m and 613km/h with WEP. They have extremely draggy airframes.

For those who dont believe TAIC uses calculated figures a lot, heres the Tony 2 TAIC Report.
http://www.wwiiaircraftperformance.org/japan/Ki-61-154B.pdf
At Sea Level they calculated 539km/h , which is very close considering it did 541km/h.
However they didnt capture this plane nor did they have full power curve of the engine.
So US intelligence stated this thing had 681km/h at 8500m. (based on a calculation using incorrect engine power curve)
Truth is the plane could only do 610km/h at 6000m at military and 620km/h at 5000m with WEP since it didnt have a supercharger which the US thought it did have.
It just proves TAIC does use calculated figures.

Hello Laurelix,
Where did you get YOUR maximum speeds for J2M3 and what were the throttle settings and altitudes the tests were conducted at?

I have actually seen a few articles and descriptions about the J2M (J2M3) including Allied pilot evaluations and no one actually faulted the aircraft for being "draggy". Manufacturing quality was actually described as being quite good from a couple sources.
I figure the J2M was a very light and tiny aeroplane with a tiny laminar flow wing and a pretty fair amount of engine power even at altitude. If they could not break 400 MPH, then SOMEBODY really screwed up the design.

We might want to ask GregP who has access to the last surviving airframe. He has posted a few photographs in the past and the aircraft looks to be a pretty clean design though of course the eyeball can deceive.

I also don't see how the ESTIMATED performance of the Ki-61-II which was never test flown has anything to do with the J2M which was test flown quite a bit by the US AND Allied pilots.
The case of the Ki-61-II is interesting because not having captured an example before the report was issued, TAIC made the assumption that the engine was pretty much a DB 605 as on the Me 109G and the engine probably wasn't quite as good.

- Ivan.

 

[Laurelix]

Hello Laurelix,
Where did you get YOUR maximum speeds for J2M3 and what were the throttle settings and altitudes the tests were conducted at?

I have actually seen a few articles and descriptions about the J2M (J2M3) including Allied pilot evaluations and no one actually faulted the aircraft for being "draggy". Manufacturing quality was actually described as being quite good from a couple sources.
I figure the J2M was a very light and tiny aeroplane with a tiny laminar flow wing and a pretty fair amount of engine power even at altitude. If they could not break 400 MPH, then SOMEBODY really screwed up the design.

We might want to ask GregP who has access to the last surviving airframe. He has posted a few photographs in the past and the aircraft looks to be a pretty clean design though of course the eyeball can deceive.

I also don't see how the ESTIMATED performance of the Ki-61-II which was never test flown has anything to do with the J2M which was test flown quite a bit by the US AND Allied pilots.
The case of the Ki-61-II is interesting because not having captured an example before the report was issued, TAIC made the assumption that the engine was pretty much a DB 605 as on the Me 109G and the engine probably wasn't quite as good.

- Ivan.

Do you know Jiro Horikoshi? He designed the A5M, A6M, J2M and A7M.
In his book, this is the J2M performance.

J2M wing area isnt exactly small, its 20.05m2
The aircraft fuselage is pretty fat and bulky. Dont forget that F6F-3 with 2000hp can only do 611km/h. J2M3 with 1820hp engine can do 613 at WEP. its by no means unrealistic.

 

[Ivan1GFP]

Hello Laurelix,

Do you know Jiro Horikoshi? He designed the A5M, A6M, J2M and A7M.
In his book, this is the J2M performance.

Never met the guy. I heard he designed some really cool aeroplanes though.....
Seriously. Which book is this from and why do you believe the data in it is more correct than other data from people who tested the aircraft? I will have to read the page in detail when I get the chance.

J2M wing area isnt exactly small, its 20.05m2
The aircraft fuselage is pretty fat and bulky. Dont forget that F6F-3 with 2000hp can only do 611km/h. J2M3 with 1820hp engine can do 613 at WEP. its by no means unrealistic.

Part of the problem here is that you have to be consistent with your numbers and these numbers are a bit misleading.
F6F-5
Speed: Around 395 MPH (sorry, DarrenW, I really don't believe the typical aeroplane could break 400 even when new)
Engine Power: 1800 HP at Altitude
Wing Area: 334 Feet^2
Weight: 12,598 pounds (From Wikipedia)

J2M3
Speed: This is what we are debating here, so I will leave it blank.
Engine Power: 1560 HP (Military at 17,900 feet)
Wing Area: 216 Feet^2
Weight: 7079 pounds (From Wikipedia)

You have an aircraft with about 2/3 the wing area, a laminar flow airfoil, weighs barely over half of what the bigger aeroplane weighs and making just over 10% less power. Why wouldn't you not expect it to go faster.
BTW, I looked at my notes on the J2M2 versus J2M3.
One of the reasons that the J2M3 might be faster is that the testing was probably done with War emergency power.
The maximum speed was achieved at 16,600 feet while testing for J2M2 gave maximum speed at 17,400 feet.

Incidentally, the ammunition loads according to a diagram I found are actually 190 rounds per gun for the Mk II cannon which are inboard and 210 rounds per gun for the Mk I cannon outboard.

- Ivan.

 

[Laurelix]

Hello Laurelix,



Never met the guy. I heard he designed some really cool aeroplanes though.....
Seriously. Which book is this from and why do you believe the data in it is more correct than other data from people who tested the aircraft? I will have to read the page in detail when I get the chance.



Part of the problem here is that you have to be consistent with your numbers and these numbers are a bit misleading.
F6F-5
Speed: Around 395 MPH (sorry, DarrenW, I really don't believe the typical aeroplane could break 400 even when new)
Engine Power: 1800 HP at Altitude
Wing Area: 334 Feet^2
Weight: 12,598 pounds (From Wikipedia)

J2M3
Speed: This is what we are debating here, so I will leave it blank.
Engine Power: 1560 HP (Military at 17,900 feet)
Wing Area: 216 Feet^2
Weight: 7079 pounds (From Wikipedia)

You have an aircraft with about 2/3 the wing area, a laminar flow airfoil, weighs barely over half of what the bigger aeroplane weighs and making just over 10% less power. Why wouldn't you not expect it to go faster.
BTW, I looked at my notes on the J2M2 versus J2M3.
One of the reasons that the J2M3 might be faster is that the testing was probably done with War emergency power.
The maximum speed was achieved at 16,600 feet while testing for J2M2 gave maximum speed at 17,400 feet.

Incidentally, the ammunition loads according to a diagram I found are actually 190 rounds per gun for the Mk II cannon which are inboard and 210 rounds per gun for the Mk I cannon outboard.

- Ivan.

I'll correct the ammo count bit later.
J2M5 with the supercharger can do 650km/h with WEP. This one reaches over 400mph.
If J2M3 could do 671, J2M5 would be 700+km/h plane. Does that sound realistic to you?

 

[Ivan1GFP]

I'll correct the ammo count bit later.
J2M5 with the supercharger can do 650km/h with WEP. This one reaches over 400mph.
If J2M3 could do 671, J2M5 would be 700+km/h plane. Does that sound realistic to you?

Hello Laurelix,
Speed calculations are not that simple either.
Power at altitude is important. Power by itself is not as you pointed out in the thread about Oscar.

The TAIC test for J2M lists 371 MPH but as condition "Overload Fighter" if I remember correctly.
That means it was doing that speed WITH A DROP TANK.

FWIW, You might want to consider that just about EVERY known piston engine fighter in WW2 had a supercharger. I think what you mean to describe is a TURBO charger. A Turbo doesn't necessarily make you go that much faster. It just is a different kind of second stage supercharger. In general, they give you better power at REALLY high altitudes (Think above 25,000 feet) but at lower altitudes, they don't give any real advantage other than drawing less power from the crankshaft.

- Ivan.

 

[Laurelix]

Hello Laurelix,
Speed calculations are not that simple either.
Power at altitude is important. Power by itself is not as you pointed out in the thread about Oscar.

The TAIC test for J2M lists 371 MPH but as condition "Overload Fighter" if I remember correctly.
That means it was doing that speed WITH A DROP TANK.

FWIW, You might want to consider that just about EVERY known piston engine fighter in WW2 had a supercharger. I think what you mean to describe is a TURBO charger. A Turbo doesn't necessarily make you go that much faster. It just is a different kind of second stage supercharger. In general, they give you better power at REALLY high altitudes (Think above 25,000 feet) but at lower altitudes, they don't give any real advantage other than drawing less power from the crankshaft.

- Ivan.

Even this agrees that J2M3 had 613km/h at WEP

F6F-5 vs J2M3

 

[gomwolf]

The US TAIC calculated the J2M performance. Its mega overoptimistic. Eventhough both J2M2 and J2M3 use the exact same engine, TAIC gives J2M2 655km/h and 671km/h to J2M3.

In reality J2M2/J2M3 had 596km/h at 5450m and 613km/h with WEP. They have extremely draggy airframes.

For those who dont believe TAIC uses calculated figures a lot, heres the Tony 2 TAIC Report.
http://www.wwiiaircraftperformance.org/japan/Ki-61-154B.pdf
At Sea Level they calculated 539km/h , which is very close considering it did 541km/h.
However they didnt capture this plane nor did they have full power curve of the engine.
So US intelligence stated this thing had 681km/h at 8500m. (based on a calculation using incorrect engine power curve)
Truth is the plane could only do 610km/h at 6000m at military and 620km/h at 5000m with WEP since it didnt have a supercharger which the US thought it did have.
It just proves TAIC does use calculated figures.

Ill trust the aircraft designer of J2M over calculated US TAIC report anyday.

AFAIK, Japanese official chart only check Mil Power but they actualy used water injection on their later war planes like J2M, Ki-84, N1K, and some others. TAIC tested or estimated WEP which used W/I. Some of their estimated data overoptimistic as you said, but I think J2M2 is quite possible figure.

And... I saw some interviews, Lt. Akio Matsuba said J2M has shorter range but It was faster and climb better than N1K-J.
In memoir of Lt. Aoki Yoshihiro, he said he could chase F6F hellcat several times.

I can't explain well cuz my language, so I just attach some data I have. I think you already have "Specification and Performance of Service Airplanes of the IJN" so I didn't attached it.

 

[Ivan1GFP]

Even this agrees that J2M3 had 613km/h at WEP

F6F-5 vs J2M3

Hello Laurelix,
That little computer analysis is fun to read but it is also a really good example of "Garbage In - Garbage Out".
The data listed in it is simply incorrect. It doesn't really match for either the Hellcat or the Raiden when compared to the test reports that are more easily found today. It was probably based on the best information commonly available from back in the 1960's, but much of the work from back then wasn't based on primary sources.

Hello Gomwolf,
Welcome to the party!
The issue with Water Injection is a weird one with Japanese aircraft. Use of Water (really Water-Methanol) injection was not an indication of War Emergency Power.
Japanese military were using fuel of 91/92 octane and needed Anti Detonant Injection even to use Military Power.
The fuel load for a late J2M3 was about 570 liters and for that small amount of fuel, there was 120 liters of Water-Methanol which is a pretty good indication of how often ADI was used.

- Ivan.

 

[Ivan1GFP]

F6F-5
Speed: Around 395 MPH (sorry, DarrenW, I really don't believe the typical aeroplane could break 400 even when new)
Engine Power: 1800 HP at Altitude
Wing Area: 334 Feet^2
Weight: 12,598 pounds (From Wikipedia)

J2M3
Speed: This is what we are debating here, so I will leave it blank.
Engine Power: 1560 HP (Military at 17,900 feet)
Wing Area: 216 Feet^2
Weight: 7079 pounds (From Wikipedia)
.

Looks like I goofed up some of the numbers. I just looked at the TAIC data sheets for Jack 11 and Jack 21 and there IS a difference in the engine ratings, so corrected numbers:

J2M3
Speed: TAIC says 417 MPH @ 16,600 feet
Engine Power: 1560 HP Military @ 18,100 feet
1785 HP War Emergency @ 16,600 feet
Wing Area: 216 Feet^2
Weight: 7320 pounds gross from TAIC

- Ivan.

 

[Laurelix]

I still think TAIC is way too overoptimistic. To get 671 out of J2M3 would be unrealistically low drag for such a bulky plane.
Ki-43-II according to TAIC has 558km/h at 6000m whereas japanese recorded 515km/h at 6000m at military power (530km/h with WEP, calculated)
theres nothing in taic regarding overload max speed for J2M.

 

[taly01]

Bulky?!?

 

[Laurelix]

Bulky?!?

View attachment 551349

yes the fuselage is fat and its prop efficiency wasnt as good.

 

[Ivan1GFP]

I still think TAIC is way too overoptimistic. To get 671 out of J2M3 would be unrealistically low drag for such a bulky plane.
Ki-43-II according to TAIC has 558km/h at 6000m whereas japanese recorded 515km/h at 6000m at military power (530km/h with WEP, calculated)
theres nothing in taic regarding overload max speed for J2M.

Hello Laurelix,
How are you calculating your WEP power? Are you also adjusting RPM?
WHICH Ki-43-II are you working with? They are not all the same.
The J2M3 is really a pretty small aeroplane and has about twice the power of Ki-43-II at very near the same altitude.
As for bulk, note that F6F-5 in a cleaned up state has reached 409 MPH though I do not believe that is a good number for a typical aircraft.

See attached for J2M3 Overload Fighter - Military Power.
First Page also added for completeness.

By the way, where is your source that the propeller on J2M wasn't good?

Hello Taly01,
Welcome to the party!

- Ivan.

 

[Laurelix]

The TAIC for J2M3 still gives higher top speed at military power at overload compared to what it could do at WEP. If Jiro Horikoshi was stating their top speed with external fuel tank, im pretty sure their climb rates wouldnt be as amazing as stated in his book.

 

[Ivan1GFP]

Do you know Jiro Horikoshi? He designed the A5M, A6M, J2M and A7M.
In his book, this is the J2M performance.
View attachment 551286

J2M wing area isnt exactly small, its 20.05m2
The aircraft fuselage is pretty fat and bulky. Dont forget that F6F-3 with 2000hp can only do 611km/h. J2M3 with 1820hp engine can do 613 at WEP. its by no means unrealistic.

Can you post a bigger image of these pages. The writing is a bit hard to read, especially the kanji.