N1K, J2M and Ki-44 vs. 1941 and 1942 vintage Bf 109

[tomo pauk]

The Ki-100 has always baffled me. It is usually reported on with glowing praise, yet on paper, seems to have 1941 era Spitfire Mk.V performance.
From Wiki;
" A well-handled Ki-100 was able to outmanoeuvre any American fighter, including the P-51D Mustangs and Republic P-47N Thunderbolts which escorted the B-29s over Japan, and was comparable in speed, especially at medium altitudes"

" The Ki-100 along with the Army's Nakajima Ki-84 and the Navy's Kawanishi N1K-J were equal to the latest Allied types in the final year of the Pacific War."

Not sure how that would be possible, considering the "latest allied types in the final year of the Pacific war" would be P-47N's, P-51D's, F4U-4 and a smattering of Spitfire MK.XIV's all of which would have enjoyed a 80 mph speed advantage

It was not possible. But, sometimes the authors give themselves too much of elbow room to try and bend the facts and figures, as well as try to wrap the stuff in shiny paper in order for their story or book sells better.
Many times it is better to translate the Japanese Wikipedia article on the Japanese stuff (as well as German-language Wiki for German stuff; same with Russian for Soviet stuff), than to go with usual English-language Wikipedia as a source.

 

[Shortround6]

edit post

 

[Shortround6]

P-40Q was a long way from a P-36, not sure what your point is here precisely

That is not a P-36 in the photo.

I find the P-36/P-40 series interesting because from the firewall back we have the same airplane (wing, fuselage, tail, etc) but powered by number of different engines and some rather different performance envelopes. It was not until the P-40Q that there was much change in either the wing or fuselage.
As I said, the plane in the photo was a P-40 (no letter) that P & W got ahold of an stuck a two stage engine similar to the engine in the F4F-4 Wildcat.
Granted in had no guns and no armor but it wound up being the 4th fastest P-40 ever built. It was faster than the P-40F/L by a measurable margin.
the P & W home Field was also home to an training squadron of P-40Fs and the experimental plane often flew mock dogfights against the P-40Fs.

The Point is that the large amount of power the P-40Q had, it wasn't much faster than the Hawk 81 experimental.
So how do you judge performance based on looks?

Here is another picture.

The two big scoops don't look very streamlined. The cowl opening doesn't look like anything special.
The exhaust pipes and ducts are very out of the ordinary for 1942/43.

This thing was supposed to be about as fast in 1942 as a Ki 84 was in 1944 according to some sources on Japanese aircraft.
The P-40Q was about as fast as some people claim the the Ki-84 was if it hand good fuel.

What I am saying is that is very hard to base anything on "looks".

 

[Wild_Bill_Kelso]

I see! So how fast was this "p-40"? What kind of supercharger?

 

[Shortround6]

Hawk 81 (P-40) with an upgraded engine from an F4F-4.
P & W claims 315mph at sea level and 388mph at 25,000ft using 1,015hp.
They estimated 370mph at 24,000ft in service condition.

as posted in post #33

Supercharger was two stage, like the -86 engine in the F4F-4
Engine was a P & W SSC7-G, supercharger gears are not listed

The -86 engine was not rated at military power by P & W but the "normal" power at 2550rpm at the three altitudes were listed.
The SSC7-G makes the same power at the same altitudes at 2550rpm. P& W did give it a military rating, it may have used a slightly different carb than the -86 engine.

 

[Wild_Bill_Kelso]

Ok sorry, I just wanted to double check i didn't miss something. Wasn't P-40Q more like 422 mph?

And no special supercharger? How is it getting 1,000 hp at 25,000'?

 

[Shortround6]

Not sure how that would be possible,

As Tomo has said, there may be a little (or more than a little) "artistic license" being used in the descriptions.

However things were somewhat relative in the summer of 1945 in Japan.

The Ki-44 had gone out of production at the end of 1944 (Nov production was 1/3 of what August had been) leaving the IJAAF with the Ki-43 in somewhat scattered production and it as near hopeless as a fighter in 1945, The Ki-84 with increasing serviceability/performance problems and the KI-61 with not only problems with the V-12 engines but a bombing raid pretty much ended V-12 production so it was the Ki-100 or.............

The Ki-100 was about as fast as a Ki-61 I and climbed better and perhaps turned a bit better? with better performance than a Ki-43 and a more reliable engine than the Ki-84 becoming a favorite of the IJAAF pilots wasn't all that hard.

The Ki-61 II had better performance but the engine was not reliable and the bombing raid had finished off any hope fixing it, Decision to use the radial engine had been made even before the bombing raid flattened the factory.

 

[Wild_Bill_Kelso]

Yeah we know that the Japanese had been bombed into oblivion by 1945, had horrible fuel and various materials shortages, had lost most of their merchant fleet and were drastically outnumbered. The discussion was really on the design level, did they make good planes? And to some extent production. (could they build them in numbers).

Of course when fleets of B-29s are incinerating your cities and US subs and dive bombers are sinking your entire merchant fleet, it's tricky to keep the factories running...

 

[Frog]

Yeah we know that the Japanese had been bombed into oblivion by 1945, had horrible fuel and various materials shortages, had lost most of their merchant fleet and were drastically outnumbered. The discussion was really on the design level, did they make good planes? And to some extent production. (could they build them in numbers).

Of course when fleets of B-29s are incinerating your cities and US subs and dive bombers are sinking your entire merchant fleet, it's tricky to keep the factories running...

A mining campaign B-29s greatly contributed to the attrition of the maritime traffic.

 

[AerialTorpedoDude69]

Japanese say ~380 mph top speed.

The source for that is a book in Japanese: Watanabe, Yoshiyuki (2000) "Shiden Kai of Local Fighter", Gakushu Kenkyusha p.180
But typical of Japanese sources, they were probably using Military rating and not WEP. There's also the question of whether this was a prototype or production version and whether it was a quote from a designer or from a pilot.

Compared to Japanese performance test conditions, very high-octane fuel would certainly not hurt, but would be unlikely to significantly improve speed performance. That is, unless modifications were done to run the engine at higher performance than design, which is unlikely.

Greg dug up the original source documentation and said it was 96-octane, not 100 or 92.

I myself am highly dubious that a Japanese 2,000 horsepower engine somehow produces a slower aircraft than a US 2,000 horsepower engine, all things being equal (let alone when factors like weight and drag are leaning heavily into the Japanese aircraft's favor, as is the case say, if you compare an N1K to an early to mid- run P-47.)

The N1K1/2 suffered from aerodynamic drag factors that was a legacy of its floatplane origins. While it had an excellent wing design featuring a low-drag airfoil, that was offset by the 4-degree attachment point between the wing and the fuselage (if I understand correctly, I could be wrong). Basically, Kawanishi rushed a design into production because they knew the Navy had no good alternative.

The Shiden Kai retained the crappy attachment point, which caused a degree of performance loss. Overall, the success of the Shiden was the result of a combination of shrewd political maneuvering between Kawanishi and Genda (who was Kawanishi's inside man in the IJN) and corruption. It definitely was a technically sophisticated aircraft but it took over a year of development to eliminate its horrendous failings. An aircraft that writes itself off in landing accidents more often than it gets shot down is a horrible aircraft.

The Japanese planes may be faster than some credit them with. But are they 420mph airplanes?

This is an interesting subject. Francillon himself said that the late-war, partially wooden Frank II made 416 MPH with the -23 and -25 models of the Homare, but didn't include a source. However, everyone points at Francillon's equally unsourced numbers when they say that the Frank wasn't as fast as TAIC's calculation. I personally believe that the early Pe-32 prop's pitch angles and length wouldn't have allowed the full horsepower to be deployed but for everyone who is treating Francillon's numbers as fact, his numbers for the Frank II are just as valid: 669 kph. That's not much different from the 687 KPH calculated by TAIC.

Again, let's be clear about this: Francillon was using Japanese numbers (which were without thrust stacks, without a fully rated -21 engine, without WEP, and were for prototypes).

We know that the -23 and -25 engines were direct injection and therefore had better fuel-air mix control at altitude. The -23 was likely 1900 HP and the -25 was the first fully rated 2,000HP engine.

 

[Frog]

A mining campaign B-29s greatly contributed to the attrition of the maritime traffic.

 

[Ivan1GFP]

Gentlemen,
I resolved a year or two ago not to get into these kinds of discussions because they always seem to be a rehash of the same topic without any consideration of what had already been discussed in the past. I have been involved in at least a half dozen threads on the same topic. It gets old when you point to the same references over and over again. It is especially difficult now because my old laptop has been out of commission for a couple of years and most of my data was there.

Here goes anyway. This will probably be my only post in this thread. The question of what the performance actually was for a Ha-45 Homare engine in good condition is actually pretty well documented by the Middletown Depot test of a Ki-84 Hayate. The performance figures (engine power) claimed by the Japanese were very nearly achieved to the point where a good engine can be believed to be capable of the power claims.
The question of Water Methanol injection or not is simply not an issue with most of the late-war Japanese engines. You simply cannot run them past maximum continuous power levels WITHOUT Water Methanol. The WM injection was not just for Emergency Use. This is quite well documented along with the specific manifold pressures at which the WM would automatically start. I won't bother linking to the Middletown Reports because I have done that at least a half dozen times in the past to no lasting effect.

One thing to keep in mind is that the N1K2-J and Ki-84 are slightly different. Their engine output is very slightly different, I believe because of the differences in the cowl and ram effect. This is only a few HP though and not all that significant overall unless you are a nit-picker like I am.

Another thing to consider is that the Homare like most Japanese engines didn't really have a War Emergency rating. The TAIC just assumed that the pilot might use the Take-Off rating as WEP because in theory he could. This matters because the typical Japanese Manual will only give performance for Rated Power (not even Military Power) and of course the Take-Off rating will give you even higher power levels though at a slightly lesser altitude.

One comment I saw early in this thread was about the armour on the N1K. There actually was NONE. Interestingly enough, armour is not what made the aeroplane tough, but that is an entirely different discussion worthy of another thread.

Now comes the opinion part: I personally believe that N1K2-J was capable of 400+ MPH. I would guess about 410 to 415 or so. The Ki 84 was probably a few MPH faster. This is on the assumption that each had a well maintained and constructed engine and good quality fuel neither of which was particularly likely at the end of the war.
As for fighting various models of the Me 109, I would say it all depends on the altitude. Under 15,000 Feet, I would pick the N1K2-J. Over 20,000 Feet, I would pick the Me 109. This is similar to what was described in Genda's Blade in encounters of N1K2-J and P-47 though without the low altitude encounters.

- Ivan.

 

[PAT303]

The discussion was really on the design level, did they make good planes? And to some extent production. (could they build them in numbers)

You could say the Japanese planes were too little too late, same for the Spitfire, like the Japanese aircraft it could have evolved into more than what it actually did but the war came first, good enough now is better than perfect later. Aircraft performance is directly related to engine power, engine power is directly related to fuel performance numbers, the Japanese like the Germans didn't have the specialist metals in quantity to build reliable 2,000hp engines or the 120-150PN fuels to fuel them as that was the exact industry the bombing campaigns targeted for obvious reasons and while the axis fighters did fight to the end neither country had aircraft that could go toe to toe with the equivalent 44-45 Allied planes.

 

[tomo pauk]

Aircraft performance is directly related to engine power, engine power is directly related to fuel performance numbers, the Japanese like the Germans didn't have the specialist metals in quantity to build reliable 2,000hp engines or the 120-150PN fuels to fuel them as that was the exact industry the bombing campaigns targeted for obvious reasons

It is not like majority of Allied A/C was powered with 2000 HP engines either. And it is not like Axis main engines' types were 27L types that were depending on 130-150 PN fuel to make high power - displacement matters as always.
Germany had 120-150 PN fuels, admittedly not in quantity required. Installing water-alcohol injection systems on engines was a workaround to deal with lack of very high PN fuels, enabling to both countries to have 1800+ HP engines in service by 1943.
BMW 801D managed 1900 HP with German high-oct fuel and without ADI, in service by 2nd half of 1943.

What was Japanese problem was that vast majority of their fighters in service were powered by small engines with under 1200 HP.

and while the axis fighters did fight to the end neither country had aircraft that could go toe to toe with the equivalent 44-45 Allied planes.

Me 262 had no equivalent among Allied planes in 44-45...

 

[PAT303]

It is not like majority of Allied A/C was powered with 2000 HP engines either.

At wars end the Merlin, Daimler Benz, Sabre, Griffon, various radials from all the makers such as the R2800 and BMW 801 were all nudging or exceeding 2,000hp reliably.

 

[PAT303]

Me 262 had no equivalent among Allied planes in 44-45...

They didn't have too, it was not a reliable or mature aircraft, too little too late.

 

[tomo pauk]

They didn't have too, it was not a reliable or mature aircraft, too little too late.

If one wants to go toe to toe vs. Allied best of 1944-45, Me 262 is still it's best bet.

 

[Shortround6]

Toe to toe gets weird.

It is sort of like the P-40 vs the Zero.

The Me 262 did some things very well and was probably the best interceptor of heavy bombers at the end of the war.

It's ability to to shoot down fighter planes is somewhat more suspect. Not that it couldn't or didn't but it's margin of superiority is a lot less.
It climbed well but not as good as the better piston engine planes of 1944/45, but the climb gradient may be different. (it may have climbed a bit slower but covered a lot more ground per minute so the competing planes wound up in different places)
It couldn't turn like the piston engine fighters (wing was about the same size as a Spitfire or Mustang) but weighed a lot more.

It was a real boom and zoom, which works well on bombers, perhaps not as good on fighters?

It had problems with acceleration, don't slow down and try to fight the prop jobs at under 400mph.

It also had a problem with the guns.
The four 30mm MK 108s were about the most powerful armament used on a single seat, single engine fighter (or even most twins) but the ammo capacity was limited (6 seconds for the 4 guns and and an extra 2 seconds for the upper guns) so combat persistence was not great.
The muzzle velocity was also poor. Which rather ruled out long range shots, forget the curved trajectory nonsense, it is a time of flight thing. Where is the target going to be when the shells get there? And with the speed of the Me 262 the amount of lead needed changed more rapidly than the slower aircraft. Back to the low amount of ammo, you don't have enough ammo to start spraying and walk the shells onto the target.

The Allied jets also had issues but their gun set ups were better suited to fighter vs fighter combat.

 

[PAT303]

If one wants to go toe to toe vs. Allied best of 1944-45, Me 262 is still it's best bet.

All that would happen is the 262 pilot would blast around not wanting to slow down or touch his throttles with the P51 Spit P47 whatever turning every time he saw the nose come around, it would end in stalemate.

 

[Vincenzo]

Spring '45; flying a P-47 try to turn with a Me 262 at 450 mph