Japanese Zero vs Spitfire vs FW 190

[Ivan1GFP]

I am profoundly agnostic on the performance of the Raiden. Fortunately, we have a survivor so it should be possible to measure everything exactly and use software developed to predict the performance of modern aircraft. The two obvious problems are cost and that there may not be good programs to predict cooling drag.

One interesting difference between the Bearcat and the J2M was that according to J2M Raiden for the Raiden "The propeller is 3.30 meters (10 feet 10 inch) diameter" (thank you for the information) whilst the Bearcat had a 12-foot-4-inch propeller (3.774 metres). Thus the volume of air accelerated by the Bearcat's propeller is 30% greater and thus for any given thrust the increase in the velocity of the air is 30% less. Does this mean that the air flowing over the Bearcat's fuselage is moving slower than the air flowing over a Raiden's fuselage? Does that reduce the Bearcat's drag or make its propeller more efficient?

Of course the cost is a longer undercarriage, weighing more, and an increased risk of propeller strikes but the short length of the Bearcat also helped.

Hello Cherry Blossom,

Regarding speeds, it would be strange for TAIC to drastically overestimate the speed of the J2M considering that they actually had quite a few captured aircraft to examine and had flying examples. They were trying to give an accurate tactical assessment of enemy aircraft that were likely to be encountered, so it would make no sense to overstate abilities.

XBe02Drvr has already given one rather extreme example of a propeller that is too small.
I believe that neither had a propeller that was extraordinarily small or large and that both were more or less optimal for their designs. I have not done much exploring with either the Raiden or the Bearcat, but I believe it would be useful to calculate the propeller power coefficients with their particular engine installations to see whether they were anything out of the ordinary and to see if they were particularly suited to high or low altitude operation.
The fact that the propeller disc is 30% larger does not necessarily mean that it moves 30% more air
One of the other issues with the propellers on the Raiden was that there was some experimentation on increasing the stiffness of the blades along with adjusting the shock mounts for the engine to reduce the engine vibrations at certain RPM ranges.

The weakness in the wings was linked to the wing folding. A Japanese Bearcat would not need folding wings if it were a land based fighter or might even be accepted on an IJN carrier without folding as it would still be smaller than their dive bombers. Either way, it would save weight and have stronger wings.

The weakness in the Bearcat's wings was a weight saving design feature. The idea was that if the outer wing sections were engineered to fail at 8-9G, the remaining wing structure which was shorter could more easily withstand the maximum 12G load before failure. The problem was that the break-away sections of the outer wing didn't hold up well in service and often did not break away symmetrically under load and the loss of one wing COULD and sometimes did cause a loss of control and a crash.

- Ivan.

 

[michael rauls]

Hello Michael Rauls,

The Ki 61-I was faster than a Me 109E but not nearly as fast as a Me 109F or G and only had the engine power of the 109E.
Its climb rate was quite low and power to weight ratio was relatively low.
Firepower was mediocre at best with 4 MG except for two versions. One was the 400 aircraft that mounted the MG 151/20 that were imported by submarine from Germany. Unfortunately after those guns were used up, there were no more coming.
The other version with good firepower was the Ki 61-Id which mounted a pair of Ho-5 20 mm cannon in the cowl. There was not enough space to mount these guns in earlier aircraft but unfortunately the Ki-61-Id also gained extra armor and was the heaviest of all and had no more engine power than any of the other versions.

So, basically with the Ki 61, you have an aircraft that handles well and can dive but can't climb well, isn't particularly fast, can't accelerate, and is not nearly as maneuverable as other J-fighters.

- Ivan.

Top speed on Bf109s is hard to nail down. Alot of different sources have alot of different numbers but as best I can make out the F had a top speed of around 370/380? The best ive seen for the mid Gs is 400.
The Ki61 was 360/370 depending on the source and had a climb of about 3000fpm which seems to be about the going rate for planes typically labelled as having a good climb rate i.e. P51, A6m, F6f etc.
Plus I believe the ki61 had more range.
Am I mistaken here?

 

[Ivan1GFP]

Top speed on Bf109s is hard to nail down. Alot of different sources have alot of different numbers but as best I can make out the F had a top speed of around 370/380? The best ive seen for the mid Gs is 400.
The Ki61 was 360/370 depending on the source and had a climb of about 3000fpm which seems to be about the going rate for planes typically labelled as having a good climb rate i.e. P51, A6m, F6f etc.
Plus I believe the ki61 had more range.
Am I mistaken here?

Hello Michael Rauls,

I believe the numbers you are quoting for Ki 61 are toward the high end.
I have not found one maximum speed listed that is over 368 MPH for the fastest version and Allied (American) testing of one version put the speed as low as 348 MPH.

The 109F-4 actually could hit speeds around 394 MPH according to the Aircraft Legends book I have next to my computer though this was probably also the ideal case.

As with most Japanese fighters, there is always the question of what power settings it was tested at.
Was it "Normal" (very unlikely in this case in my opinion) or was it "Military"?
Would it have gone faster if they had run it at Take-Off RPM instead of Military? (2500 RPM versus 2400 RPM)
Did it have enough supercharger to run Take-Off Boost +330 mm at altitude instead of Military +240 mm?

- Ivan.

 

[tomo pauk]

Hello Tomo Pauk,

Regarding the internal fuel load of the Ki 61-I, you are simply incorrect. Early aircraft seemed to carry the larger fuel loads, but the wing tanks varied in size and the fuselage tank was not always installed especially in later aircraft.

EDIT for more detail

The Ki 61-Ia had the following
2 x 190 liter Wing Tanks
1 x 170 liter Wing Center Tank
1 x 200 liter Fuselage Tank
-----------------------------
Total 750 liters

Ki 61-Ib had three variations
early production was same as -Ia (s/n 501-513)
mid production deleted the fuselage 200 liter tank for a new total of 550 liters (s/n 514-649)
late production (s/n 650-1092) had the following
2 x 170 liter Wing Tanks
1 x 160 liter Wing Center Tank
No Fuselage Tank
----------------------------
Total 500 liters

Ki 61-Ic had the following
2 x 170 liter Wing Tanks
1 x 160 liter Wing Center Tank
No Fuselage Tank
----------------------------
Total 500 liters

Ki 61-Id had the following
2 x 170 liter Wing Tanks
1 x 160 liter Wing Center Tank
1 x 95 liter Fuselage Tank
----------------------------
Total 595 liters

You are right that not every single Ki 61 was with great fuel capacity.
We can also take a look at minimum internal fuel figures for the J2M. For example, Allied credited it with 111 US gals here - last place between Japanese fighters of ww2.

The two drop tanks carried by the Ki 61 were only 200 liter capacity each, so it carries no more fuel in drop tanks than the J2M did.

We can cut this JM2 fuel situation anyway we want. Bottom line is that it carried no more fuel than Japanes fighters powered by 1000-1200 HP engines, while being powered by a 30-50% more powerful engine = short range.

When you say "needed by late 1943", I take this to mean "needed at its introduction" which was 1943. It was always somewhat underpowered.

Yes, it could have used an extra 20-30% more power, let alone 50% more.
OTOH - it have had better power to weight ratio than P-40B by some 10%.

The problem with expecting decent performance out of 'your' fighter is that it is hard to see your requirements adding LESS than 50% more weight than the current carrier-borne fighter.

- Ivan.

Gruman did the same what I propose here when they went from Wildcat to Hellcat.

 

[XBe02Drvr]

Gruman did the same what I propose here when they went from Wildcat to Hellcat.

With a 67% increase in horsepower!

 

[tomo pauk]

With a 67% increase in horsepower!

Yes - similar to what Kasei offered over Sakae.

 

[Ivan1GFP]

You are right that not every single Ki 61 was with great fuel capacity.
We can also take a look at minimum internal fuel figures for the J2M. For example, Allied credited it with 111 US gals here - last place between Japanese fighters of ww2.

Hello Tomo Pauk,

That same table you are referencing credits the J2M2 (Jack 11) with 111 Gallons + 48 Gallons Internal Removable fuel tanks.
That makes a total of 159 Gallons internal fuel or 601 Liters which is pretty consistent with other references.

We can cut this JM2 fuel situation anyway we want. Bottom line is that it carried no more fuel than Japanes fighters powered by 1000-1200 HP engines, while being powered by a 30-50% more powerful engine = short range.

I never made a claim that the J2M was anything other than a point defence interterceptor == short range.
My point was that with THAT engine, the Kasei, you would need a LOT more fuel to get decent range and that the Kasei was probably not the ideal engine for the purpose.

Yes, it could have used an extra 20-30% more power, let alone 50% more.
OTOH - it have had better power to weight ratio than P-40B by some 10%.

We are in agreement here. The P-40B was certainly obsolete by 1943. Also remember that the P-40B gained quite a lot of weight when armour was added in the P-40C version in 1941. If the Ki 61-I had been introduced in 1941, I believe it would have been competitive but its performance level was quite below the standard by 1943 at its ACTUAL introduction. It had some redeeming characteristics, but performance was not so good.

Gruman did the same what I propose here when they went from Wildcat to Hellcat.

The construction / strength and equipment standard between Wildcat and Hellcat is not quite as different as that between the A6M and the next generation Japanese carrier fighter. Also, keep in mind that the performance level of the Hellcat was not quite adequate by the end of the Pacific war.

- Ivan.

 

[tomo pauk]

Hello Tomo Pauk,

That same table you are referencing credits the J2M2 (Jack 11) with 111 Gallons + 48 Gallons Internal Removable fuel tanks.
That makes a total of 159 Gallons internal fuel or 601 Liters which is pretty consistent with other references.

Minimum internal fuel of JM2 of 111 US gals (420) liters is less what was minimum for the Ki 61 (=500 L); max internal fuel for the J2M was smaller (159 gals) than of the Ki 61 (199 US gals). Now yes, we have a situation of versions of the Ki 61 carrying 595L, indeed less than 601L for the JM2 by 6 liters.
Once we calculate in that Kasei was making 20-50% more power (depending on version and altitude) than Ha-40, it will not take a rocket scientist to arrive to a conclusion that JM2 was not carrying enough fuel to be a long range fighter.

I never made a claim that the J2M was anything other than a point defence interterceptor == short range.
My point was that with THAT engine, the Kasei, you would need a LOT more fuel to get decent range and that the Kasei was probably not the ideal engine for the purpose.

Kasei was not an ideal engine, but it was the best what Japanese have had avaliable between late 1941 and early '44.
A Kasei-powered (plain-vanilla engine - no extension shaft or counter-rotaing 'nose' needed) fighter size of P-51/N1K-J/Bearcat with 200 gals of internal fuel and two drop tanks, produced in decent numbers, would've been an excellent additon to the Japanese war effort in 1942-44.

We are in agreement here. The P-40B was certainly obsolete by 1943. Also remember that the P-40B gained quite a lot of weight when armour was added in the P-40C version in 1941. If the Ki 61-I had been introduced in 1941, I believe it would have been competitive but its performance level was quite below the standard by 1943 at its ACTUAL introduction. It had some redeeming characteristics, but performance was not so good.

An actually working Ki 61 was probably the best Japanese fighter in 1943 historically.

The construction / strength and equipment standard between Wildcat and Hellcat is not quite as different as that between the A6M and the next generation Japanese carrier fighter. Also, keep in mind that the performance level of the Hellcat was not quite adequate by the end of the Pacific war.

- Ivan.

Hellcat was vastly better than the best Japanese carrier-borne fighter - exactly what I'm after here.
Japanese managed to skip a generation of carrier-borne fighters after the Zero (unlike the Americans, and unlike what they did with their dive- and torpedo-bombers) and thus shot themselves in another foot.

 

[Ivan1GFP]

Minimum internal fuel of JM2 of 111 US gals (420) liters is less what was minimum for the Ki 61 (=500 L); max internal fuel for the J2M was smaller (159 gals) than of the Ki 61 (199 US gals). Now yes, we have a situation of versions of the Ki 61 carrying 595L, indeed less than 601L for the JM2 by 6 liters.
Once we calculate in that Kasei was making 20-50% more power (depending on version and altitude) than Ha-40, it will not take a rocket scientist to arrive to a conclusion that JM2 was not carrying enough fuel to be a long range fighter.

Hello Tomo Pauk,

First of all, I believe you have a bit too much faith in the "removable" fuel tanks for J2M2 (Jack 11).
Second, the only the early versions of the Ki 61-I had 750 liters of internal fuel. As described earlier, the rest had considerably less.
The later production version, J2M3 (Jack 21) most certainly DID have 570 liters of internal fuel.
Another issue is that the fighters with engines in the 1000 HP range did not typically carry anti detonant and the Kasei needed quite a bit of it in order to even run at military power. Add a 120 liter water-methanol tank and the "fuel weight" of the Kasei equipped J2M becomes quite proportional to its power increase but the range does not increase.

Kasei was not an ideal engine, but it was the best what Japanese have had avaliable between late 1941 and early '44.
A Kasei-powered (plain-vanilla engine - no extension shaft or counter-rotaing 'nose' needed) fighter size of P-51/N1K-J/Bearcat with 200 gals of internal fuel and two drop tanks, produced in decent numbers, would've been an excellent additon to the Japanese war effort in 1942-44.

The earlier Kasei had a much lower power level than the one used in the J2M fighter. I don't believe a 1942 engine would have given worthwhile performance. The later version needed anti detonant as did most other higher powered Japanese engines.
Your 200 Gallons of internal fuel just became about 250 Gallons when you consider than an additional tank and plumbing is needed and that the water-methanol mixture is heavier than fuel.

An actually working Ki 61 was probably the best Japanese fighter in 1943 historically.

Your opinion, not necessarily shared by the pilots.

Hellcat was vastly better than the best Japanese carrier-borne fighter - exactly what I'm after here.
Japanese managed to skip a generation of carrier-borne fighters after the Zero (unlike the Americans, and unlike what they did with their dive- and torpedo-bombers) and thus shot themselves in another foot.

There wasn't a next generation of Japanese carrier fighter other than vapor ware.
You seem to be stuck on the Kasei. I believe more could have been gained by resolving the problems with the Homare engine instead. From the Middletown rework of Ki 84, there wasn't anything basically wrong with the Homare other than poor quality accessories which would have affected any engine.

- Ivan.

 

[Conslaw]

The Ki-61 was approximately equal to the P-40N in performance. However there were 5220 P-40N models built and only 3,078 of all Ki-61s.

 

[tomo pauk]

...
Another issue is that the fighters with engines in the 1000 HP range did not typically carry anti detonant and the Kasei needed quite a bit of it in order to even run at military power. Add a 120 liter water-methanol tank and the "fuel weight" of the Kasei equipped J2M becomes quite proportional to its power increase but the range does not increase.

Nobody was calcuating the ADI carried into weight of fuel, let's not start doing it in 2020.

The earlier Kasei had a much lower power level than the one used in the J2M fighter. I don't believe a 1942 engine would have given worthwhile performance. The later version needed anti detonant as did most other higher powered Japanese engines.
Your 200 Gallons of internal fuel just became about 250 Gallons when you consider than an additional tank and plumbing is needed and that the water-methanol mixture is heavier than fuel.

Later versions were able to use ADI, that was a feature, not a bug. People were very happy to implement ADI when possible - be that Americans, Germans or Japanese.
The 1942 Kaseis (13, 14, 15) were good for 1280 HP at 19800 ft ('military power' per Americans) or 1405 HP at 19000 ft ('WER dry' per Americans, even if in this case it also included over-revving from 2350 to 2450 rpm) - akin to the 50% heavier BMW 801D of the era, and much more reliable.

Your opinion, not necessarily shared by the pilots.

Fair enough.

There wasn't a next generation of Japanese carrier fighter other than vapor ware.

That is what it's all about.

You seem to be stuck on the Kasei. I believe more could have been gained by resolving the problems with the Homare engine instead. From the Middletown rework of Ki 84, there wasn't anything basically wrong with the Homare other than poor quality accessories which would have affected any engine.

- Ivan.

I'm all for solving the problems with Homare. When tested by 'West', it proved to be an excellent engine.
Quirk is here that Kasei was a much earlier engine, as-is, in both production and service, and it is in production at another company. Homare can be installed on a fighter's new versions by 1944, meaning thet something much better than Sakae is needed in 1942-44.

 

[Clayton Magnet]

Your opinion, not necessarily shared by the pilots.

Out of curiosity, what Japanese fighter would have been considered superior to the Ki-61 in 1943? Ki-44 maybe

 

[Ivan1GFP]

The Ki-61 was approximately equal to the P-40N in performance. However there were 5220 P-40N models built and only 3,078 of all Ki-61s.

Hello Conslaw,

The P-40N was a bit faster, better climb rate and had a much better power to weight ratio. Note the comparison that Tomo Pauk made was to the P-40B, a much earlier aircraft. Firepower would vary depending on whether we are comparing the cannon armed or MG only Ki 61-I.

Nobody was calcuating the ADI carried into weight of fuel, let's not start doing it in 2020.

Hello Tomo Pauk,

Perhaps people SHOULD have been calculating the weight of ADI because for a Japanese engine, it IS a part of the fuel load.

Later versions were able to use ADI, that was a feature, not a bug. People were very happy to implement ADI when possible - be that Americans, Germans or Japanese.

If you are making this comparison, then you don't really understand how the Japanese engines used ADI. They didn't carry 120 liters of water-methanol because they WANTED to. They needed ADI even to run MILITARY power.

The 1942 Kaseis (13, 14, 15) were good for 1280 HP at 19800 ft ('military power' per Americans) or 1405 HP at 19000 ft ('WER dry' per Americans, even if in this case it also included over-revving from 2350 to 2450 rpm) - akin to the 50% heavier BMW 801D of the era, and much more reliable.

That is an interesting point of view and I do see the merits. The problem though is that the "do-everything" carrier fighter isn't going to be as tiny as a FW 190A.

I'm all for solving the problems with Homare. When tested by 'West', it proved to be an excellent engine.
Quirk is here that Kasei was a much earlier engine, as-is, in both production and service, and it is in production at another company. Homare can be installed on a fighter's new versions by 1944, meaning thet something much better than Sakae is needed in 1942-44.

This is kind of the chicken-egg problem. You need an engine but you also need an appropriate airframe to install it in. A6M really wasn't it but could have been improved to an extent with the Kinsei at some point. How early would an airframe need to be developed to be in service by 1942? What other engines were available?

Out of curiosity, what Japanese fighter would have been considered superior to the Ki-61 in 1943? Ki-44 maybe

Hello Clayton Magnet,

I believe that the Ki 43 was often preferred over the Ki 61. The Ki 44 makes better sense though.

- Ivan.

 

[tomo pauk]

Perhaps people SHOULD have been calculating the weight of ADI because for a Japanese engine, it IS a part of the fuel load.

Sorry, I don't agree with that.

If you are making this comparison, then you don't really understand how the Japanese engines used ADI. They didn't carry 120 liters of water-methanol because they WANTED to. They needed ADI even to run MILITARY power.

I'm hardly a sharpest tool in the tollbox, and indeed I don't understand quite a lot.
On the other hand, reading the available data for the Kasei 10 series reveals that they will run even emergency rating (max power 1530 HP) without ADI, provided 92 oct fuel is used. With ADI, the Kasei 20 series will do 1880-1940 HP per Americans.
The respective data tables can be easily found on this forum, Techincal section.
Nakajima's Ha-41 and -109 also didn't used ADI for any power setting.

That is an interesting point of view and I do see the merits. The problem though is that the "do-everything" carrier fighter isn't going to be as tiny as a FW 190A.

It will be probably size of P-51, N1KJ-1, or Bearcat.

This is kind of the chicken-egg problem. You need an engine but you also need an appropriate airframe to install it in. A6M really wasn't it but could have been improved to an extent with the Kinsei at some point. How early would an airframe need to be developed to be in service by 1942? What other engines were available?

Mitsubishi was producing Kasei and Kinsei, the later was installed (too late to matter) into A6M8 prototypes and, under another name, into Ki-100. Nakajima was making Ha-41/109 series, the Ha-109 was delivering about same power as the BMW 801C, but at much lower weight.
New naval fighter design(s) need to be put on the paper by time the design process for the Zero is done.

 

[Ivan1GFP]

Sorry, I don't agree with that.

Hello Tomo Pauk,

Whether you agree with it or not, the bottom line is that the Kasei 23 engine NEEDED ADI in order to safely make military power.
At least that was the determination of the engineers at the time. I do not believe either of us has superior information to be able to determine that they were incorrect with the quality of fuel that they had available.

I'm hardly a sharpest tool in the tollbox, and indeed I don't understand quite a lot.
On the other hand, reading the available data for the Kasei 10 series reveals that they will run even emergency rating (max power 1530 HP) without ADI, provided 92 oct fuel is used. With ADI, the Kasei 20 series will do 1880-1940 HP per Americans.
The respective data tables can be easily found on this forum, Techincal section.
Nakajima's Ha-41 and -109 also didn't used ADI for any power setting.

I am not commenting on intelligence. There are things each of us doesn't know which is why these forums are so interesting. Much as we seem to be disagreeing here, I have great respect for you.

The next question one should ask after noting which engines do not use Anti Detonant is what boost levels were those engines using when they did NOT use ADI.
The Sakae 21 engine also did not use ADI but it was only reaching +300 mm boost at Take-Off.
The Kasei 23 as used in Raiden was able to use +450 mm boost at Take-Off
The Homare / Ha-45 as used in Ki 84 was using +500 mm boost at Take-Off and even at a maximum cruise rating of +200 mm was using ADI.
You don't need to take my word for it. The report on the Middletown Ki 84 is available on these forums.
IIRC, the ADI came on automatically at +180 mm boost.
That is why for 700 liters of internal fuel, it was carrying 130 liters of water-methanol.

It will be probably size of P-51, N1KJ-1, or Bearcat.

The problem is that you are asking for features that each of those aircraft lacks. The P-51 has a particularly economical engine and isn't a naval fighter. The N1K-J never had the range you are calling for and neither did the Bearcat.

The N1K2-J also had essentially no armour at all which doesn't meet requirements. Even with much less range than the A6M series which means it does not meet your requirements, it carried 716 liters of internal fuel and about 140 liters of water-methanol needed to run the engine.
Whether you consider it fuel or not, it means that this aeroplane was carrying 189 Gallons of Gasoline and another 37 Gallons of something considerably heavier than Gasoline. It also could carry the 400 liter drop tank and even with that, it could not come close to the A6M.

Mitsubishi was producing Kasei and Kinsei, the later was installed (too late to matter) into A6M8 prototypes and, under another name, into Ki-100. Nakajima was making Ha-41/109 series, the Ha-109 was delivering about same power as the BMW 801C, but at much lower weight.
New naval fighter design(s) need to be put on the paper by time the design process for the Zero is done.

It doesn't sound like there were a lot of choices for designing a new fighter with all the requirements you are asking for at the time that such a design needed to be done. It would be pretty hard to commit to a design without the knowledge of which engine would be developed to what extent. Who would have thought in 1940 that the Sakae 21 would have such a minimal power increase and the Sakae 31 would not work out? The ADI system worked out for Hayabusa.

- Ivan.

 

[tomo pauk]

Hello Tomo Pauk,
Whether you agree with it or not, the bottom line is that the Kasei 23 engine NEEDED ADI in order to safely make military power.
At least that was the determination of the engineers at the time. I do not believe either of us has superior information to be able to determine that they were incorrect with the quality of fuel that they had available.

My comment: if a Japanese pilot is going to extract a lot of power from his Kasei via ADI , he might as well go for the whole hog = into 'WER wet'.

I am not commenting on intelligence. There are things each of us doesn't know which is why these forums are so interesting. Much as we seem to be disagreeing here, I have great respect for you.

Thank you for the kind words. I can just reflect the same feelings towards you.

The next question one should ask after noting which engines do not use Anti Detonant is what boost levels were those engines using when they did NOT use ADI.
The Sakae 21 engine also did not use ADI but it was only reaching +300 mm boost at Take-Off.
The Kasei 23 as used in Raiden was able to use +450 mm boost at Take-Off
The Homare / Ha-45 as used in Ki 84 was using +500 mm boost at Take-Off and even at a maximum cruise rating of +200 mm was using ADI.
You don't need to take my word for it. The report on the Middletown Ki 84 is available on these forums.
IIRC, the ADI came on automatically at +180 mm boost.
That is why for 700 liters of internal fuel, it was carrying 130 liters of water-methanol.

Kasei 21 and 25 run at +160 mm Hg before ADI was engaged, and up to +450 mm Hg with ADI.
Kasei 11 and 15 were good for +270 mm Hg wthout ADI (take-off setting, 1530 or 1460 HP respectively, per Japanese; there was no option for ADI there), and +180 for rated power (= 1340 CV at 4300 m or 1300 CV at 6000 m, respectively, per Japanese).

The problem is that you are asking for features that each of those aircraft lacks. The P-51 has a particularly economical engine and isn't a naval fighter. The N1K-J never had the range you are calling for and neither did the Bearcat.

I don't ask for anything from those aircraft apart the size.

The N1K2-J also had essentially no armour at all which doesn't meet requirements. Even with much less range than the A6M series which means it does not meet your requirements, it carried 716 liters of internal fuel and about 140 liters of water-methanol needed to run the engine.
Whether you consider it fuel or not, it means that this aeroplane was carrying 189 Gallons of Gasoline and another 37 Gallons of something considerably heavier than Gasoline. It also could carry the 400 liter drop tank and even with that, it could not come close to the A6M.

As before - plain-vanilla Kasei in the nose, size as mentioned, 200 gals of internal fuel + two drop tanks, Butterfly flaps, folding wing, 4 cannons. When better Kasei is available - use it. Homare is available - use that. ADI - install when available.

It doesn't sound like there were a lot of choices for designing a new fighter with all the requirements you are asking for at the time that such a design needed to be done. It would be pretty hard to commit to a design without the knowledge of which engine would be developed to what extent. Who would have thought in 1940 that the Sakae 21 would have such a minimal power increase and the Sakae 31 would not work out? The ADI system worked out for Hayabusa.

- Ivan.

I'd say that 3 separate engine lines (Kasei, Kinsei, Ha-41/109) is quite a choice, and are in actual use before 1942 (bar the Ha-109). It will not take a rocket scientist to quickly came into conclusion that 28L Sakae can't compete vs. 32-42L engines produced in Japan, let alone Western engines that were know to exist before 1940/41 (R-2180E, R-2600, or big liquid cooled 12 cylinder engines).

 

[XBe02Drvr]

The P-51 has a particularly economical engine and isn't a naval fighter.

No more economical than any other Merlin powered aircraft. What it had was a particularly economical airframe in terms of L/D, largely due to a couple of features that were "not quite ready for prime time" in 1940 Japan, and a design philosophy that would have been a hard sell in that place and time.
Plus, the Japanese had been focusing so long on radials for their light weight, they were a little behind the curve on liquid cooling. Witness their issues when handed the DB600 series engines fully developed, no R&D required.
Cheers,
Wes

 

[Shortround6]

"economical engine"

We have to be rather careful here as the Merlin was never a particularly economical engine. At least in regards to power per pound (or gallon) of fuel burned. It had about the lowest compression ratio of any western engine (at least the major ones). The Allison was figured to be about 5-8% more economical and the radials did pretty good, at least on the HP/lbs of fuel/hr ratings at cruise settings. Things change when the air cooled engines went to rich settings (they were using extra fuel as a coolant) and then you have have the whole installation drag thing to figure out. For a few years the liquid cooled engines had a rather lower drag for the installed power advantage but that narrowed by the end of WW II. Post war it's gets a bit iffy as some of the commercial radial engine installations got pretty good but nobody was really working on the liquid cooled installations anymore.

 

[Ivan1GFP]

My comment: if a Japanese pilot is going to extract a lot of power from his Kasei via ADI , he might as well go for the whole hog = into 'WER wet'.

Hello Tomo Pauk,

That seems like a pretty odd way to run an engine. Either economical cruise or War Emergency.

Kasei 21 and 25 run at +160 mm Hg before ADI was engaged, and up to +450 mm Hg with ADI.
Kasei 11 and 15 were good for +270 mm Hg wthout ADI (take-off setting, 1530 or 1460 HP respectively, per Japanese; there was no option for ADI there), and +180 for rated power (= 1340 CV at 4300 m or 1300 CV at 6000 m, respectively, per Japanese).

The Kasei 21 and 25 sound like twins to the Kasei 23 in the Raiden as far as throttle settings.
The other seem quite a bit more limited in their ultimate performance.

As before - plain-vanilla Kasei in the nose, size as mentioned, 200 gals of internal fuel + two drop tanks, Butterfly flaps, folding wing, 4 cannons. When better Kasei is available - use it. Homare is available - use that. ADI - install when available.

Consider how the vapor ware fighter stacks up against the Shiden-KAI. It needs range equivalent to A6M, but the N1K2-J carries even more internal "fuel" than your specification but has considerably less range. How big do you intend for those "two drop tanks" to be? The N1K2-J was already carrying a 400 liter drop tank and still had less range.
The N1K2-J had decent performance, but it also had a much more powerful Homare engine with water-methanol injection to achieve it. It carried no equipment for a carrier fighter and other than some bullet proof glass, it had no armour.
Do you really think that adding equipment and armour and fuel for extra range and reducing engine power is going to result in reasonable performance?

'd say that 3 separate engine lines (Kasei, Kinsei, Ha-41/109) is quite a choice, and are in actual use before 1942 (bar the Ha-109). It will not take a rocket scientist to quickly came into conclusion that 28L Sakae can't compete vs. 32-42L engines produced in Japan, let alone Western engines that were know to exist before 1940/41 (R-2180E, R-2600, or big liquid cooled 12 cylinder engines).

I believe what you are not taking into account is that the Sakae was a higher revving engine than the Kasei. Who would have thought that when they went from Sakae 12 to Sakae 21, the gain in HP would be nearly nothing except not quite 2000 meters in critical altitude when the boost was raised and RPM was raised as well?
Even the Homare wasn't a particularly large displacement engine at just a bit under 36 liters.

No more economical than any other Merlin powered aircraft. What it had was a particularly economical airframe in terms of L/D, largely due to a couple of features that were "not quite ready for prime time" in 1940 Japan, and a design philosophy that would have been a hard sell in that place and time.

Hello XBe02Drvr, Shortround6,

Thanks for the reminder. I was thinking more of the Merlin versus R-2800 when I wrote "economical".

Plus, the Japanese had been focusing so long on radials for their light weight, they were a little behind the curve on liquid cooling. Witness their issues when handed the DB600 series engines fully developed, no R&D required.

The story of the Ha-40 is a bit more complicated than that. The original engine that they were "handed" was a DB-601Aa which was the low rated version. What they and probably everyone else wanted was the DB-601A-1.which had less low altitude power but a higher critical altitude. The Japanese took that engine, lightened it a bit and also improved the supercharger enough to bring the critical altitude very close to that of the A-1 engine.
There is also the issue of having the plans for an object and not having the manufacturing capability to make it. There are plenty of modern examples of this kind of thing.

- Ivan.

 

[tomo pauk]

Hello Tomo Pauk,
That seems like a pretty odd way to run an engine. Either economical cruise or War Emergency.

Not much of an economical cruise - 1240 HP in low gear. That's 20% more than max power of the late Sakae versions.

The Kasei 21 and 25 sound like twins to the Kasei 23 in the Raiden as far as throttle settings.
The other seem quite a bit more limited in their ultimate performance.

The other (Kasei 11) was early engine - used from 1941.

Consider how the vapor ware fighter stacks up against the Shiden-KAI. It needs range equivalent to A6M, but the N1K2-J carries even more internal "fuel" than your specification but has considerably less range. How big do you intend for those "two drop tanks" to be? The N1K2-J was already carrying a 400 liter drop tank and still had less range.
The N1K2-J had decent performance, but it also had a much more powerful Homare engine with water-methanol injection to achieve it. It carried no equipment for a carrier fighter and other than some bullet proof glass, it had no armour.
Do you really think that adding equipment and armour and fuel for extra range and reducing engine power is going to result in reasonable performance?

664 L (175.4 US gals) of the internal fuel of the Shiden-Kai is less than 200 US gals I've proposed. Two drop tanks of 300 or 400 liters should complement that fine.
Against the Zero - yes, we have more stuff in the aircraft, but also much more power.

I believe what you are not taking into account is that the Sakae was a higher revving engine than the Kasei. Who would have thought that when they went from Sakae 12 to Sakae 21, the gain in HP would be nearly nothing except not quite 2000 meters in critical altitude when the boost was raised and RPM was raised as well?

A 10% greater RPM of 'engine X' is no match for 50% greater displacement of 'engine Y'. Everybody knew that - P&W, Wright, DB, RR, Bristol, Soviets, Japanese.

Even the Homare wasn't a particularly large displacement engine at just a bit under 36 liters.

Okay.