Jack vs. Tojo - Which was better? Why?

[Clayton Magnet]

Technically the Ki-44 II has 6/50-cal and 2/40mm cannons

I was under the impression that the Shoki would have at most four machine guns. Two synchronized Ho-103 in the fuselage, and one in each wing. Was there actually provision for six to be installed?

 

[GrauGeist]

I was under the impression that the Shoki would have at most four machine guns. Two synchronized Ho-103 in the fuselage, and one in each wing. Was there actually provision for six to be installed?

From what I've read, the KI-44 in it's various configurations never had more than two weapons in the cowl and one in each wing.
The cowl positions were either 7.7mm or 12.7mm MGs and the wing positions were either 12.7mm MGs or 40mm cannon.

There were proposals to upgun to cannon in all positions, but these remained on paper.

 

[Reluctant Poster]

Is the IJN the only carrier force to specify a frontline fighter incapable of flying from its carriers? Why not make the Jack carrier capable or divert its resources to a carrier fighter? Since when is it the navy's job to intercept B-29s? That nation was messed up.

The US wasn't exactly immune to interservice rivalry, the Japanese were just a little more extreme.

 

[cherry blossom]

I have been struggling with the information in this thread that most versions of the Kinsei 60 series did not use methanol water injection at military power and above.

Firstly, according to Goodwin and Starkings, water injection was introduced from the Kinsei 52 and 53 (MK8B and MK8C). There is no obvious need to change the system for adding water to air - fuel mixture on changing to the direct injection of fuel, so the water may have been added before the supercharger (hopefully the methanol should not require backfire screens).

Secondly, if we use that famously accurate source, Wikipedia, to find the power of the P&W R-2000 Pratt & Whitney R-2000 Twin Wasp - Wikipedia we find "The R-2000 produced 1,300 hp @ 2,700 rpm with 87 octane, 1,350 hp with 100 octane and 1,450 hp @ 2,800 rpm with 100/130-grade fuel." With almost the same swept volume, the Ha-112 II gave 1,500 ps @ 2,600 rpm with 92 octane. Unfortunately, the boost is given as unknown by G & S on page 119 but it seems to me that it would need to be high enough to require either 100/130 octane fuel or water injection even if the use of direct injection allowed better scavenging via keeping the exhaust valve open longer.

There is a Ki-100 at Cosford (see thread Kawasaki Ki 100 shots). Can someone go over and count the ports for adding liquids? Is Joe Picarella in the house?

 

[Vincenzo]

For the information in the engines section, Shinpachi works, Kinsei 61 had not water injection but the Kinsei 61-ru or 62-ru (it's possible a mistyping) had it

 

[GregP]

I was under the impression that the Shoki would have at most four machine guns. Two synchronized Ho-103 in the fuselage, and one in each wing. Was there actually provision for six to be installed?

According to several sources, yes. I can't say for sure, never having seen a Ki-44 of any variant. The armament claim comes for the TAIC manual No. 2, dated 1945, so they probably knew a thing or two about the Ki-44 II by then.

 

[Shortround6]

Well for some of these engines a lot depends on the altitude. and some depends on time.
The US engines were rated at 5 minutes of time subject to engine staying within temperature limits.
I don't know about the Japanese engines, if they had a 1 minute or 3 minute rating or 5 minute.

I would also note that not all superchargers were created equal. P&W tended to use a pretty small supercharger (in capacity ) so it would use the least amount of power at take-off.

A R-2000 was good for 1450hp using 49.5in MAP (1258mm) +9.8lb
However it was only good for take-off and up to 1000ft.
In high gear it was good for 1100hp at 16,000ft.

Some engines that were rated at 1350hp (and many of them were rated using 100/130 fuel) would give you the 1350hp at 3000ft in low gear but only 1100hp in high gear at 16,000ft.
Some engines were given different ratings depending on what kind of main bearings they used.

Some of the engines rated on 100 octane fuel were rated at 1350hp at take-off/2000ft. In high gear they were rated at 1100hp at 13,200ft. ( a different gear ratio for high gear)

These are all at 2700rpm.

P & W doesn't seem to have rated the engine for 87 octane. They have one listing using 90 octane but the engine was never was never manufactured. (a lot of these not manufactured engines got model numbers) The Military may very well have rated the engine/s for 87 octane fuel in the manuals for when the planes could not get 100 or 100/130.
A 1945 manual has a quick chart for using 91 octane fuel. The engine is restricted to 1200hp for take-off using 43.5in of map

A British manual (?) might show 87 octane. 91 octane was a US fuel only. At least during the war

The Ha-112-II while rated for 1500hp/2600rpm for take-off was only rated at 1350hp/2500rpm at 6,500ft and 1250hp/2500rpm at 19,500ft. Both which handily beat a R-2000 running at 2550rpm (Normal or max continuous )

The other thing to consider is that the P & W engines were rather conservatively rated. the older R-1830 was rated at close to 1000 hours for transport use. Japanese engines may have been pushed harder (higher temps or something else?)

 

[GrauGeist]

Here's a photo of a captured KI-44-II in the Philippines, 1945 - one weapon in each wing.

I suspect poorly worded descriptions can mislead, for example, many sites state: "it had two machine guns in the cowl and two in the wings", giving the impression of "two in each wing".
The armament would be better described with: "it had two machine guns in the cowl and one in each wing".

 

[GregP]

I checked the TAIC manual and the actual description reads, "2/12.7/250 + 2/40/10 or 4/12.7/250." I HAVE seen a source that claims 6 guns, but that was some time back and I can't recall the source exactly. So ... no exact recall for the source generally equals no second source in this forum.

I stand corrected.

I would think that 10 rounds of 40 mm would only be for a bomber interceptor and I would remove the 40s and replace with 20s and more ample ammo supply if I were in command.

 

[GrauGeist]

I would think that 10 round of 40 mm would only be for a bomber interceptor and I would remove the 40s and replace with 20s and more ample ammo supply if I were in command.

You're not far off the mark, Greg - as I recall, the 40mm gave them a great deal of trouble, so they replaced them with the 12.7mm MG.

 

[Greg Boeser]

Some simply removed the cannon, leaving just the nose guns.

 

[Shortround6]

here is a drawing from Wiki on the 40mm projectile

There was no cartridge case, the propellent was in the base of the projectile.

Basically what the Japanese had was gun/rocket launcher that with 1/2 the velocity of the German MK 108, fired a bit slower, and a shell that had about 2/3rds of the explosive.
And the magazine held 10 rounds. weapon could empty the magazine in in about 1.25 seconds.

 

[BiffF15]

I just went back through the majority of this thread and have a couple of questions for the knowledgable.

Early on there are comparisons made between the P47N and the J2M3. The speeds and climb rates that I saw were for a max loaded P47 and not one at about half gas over Japan. Does anyone have the charts for a no longer tanked but still with pylons at approx half fuel weight for a P47N? This conversation for a bit was just like the Mustang vs 109 chart comparison seen in other threads.

I only bring this up as a plane with 33% it's weight being fuel will have a big gain in climb rates once it's down to half fuel vice a plane that only has 150 gallons (10% of it's weight) at takeoff. When a Thunderbolt met a Jack over Japan, its weight would be much lower, and it's climb rate I would think much higher. Numbers are for example only.

Cheers,
Biff

 

[GregP]

I just went back through the majority of this thread and have a couple of questions for the knowledgable.

Early on there are comparisons made between the P47N and the J2M3. The speeds and climb rates that I saw were for a max loaded P47 and not one at about half gas over Japan. Does anyone have the charts for a no longer tanked but still with pylons at approx half fuel weight for a P47N? This conversation for a bit was just like the Mustang vs 109 chart comparison seen in other threads.

I only bring this up as a plane with 33% it's weight being fuel will have a big gain in climb rates once it's down to half fuel vice a plane that only has 150 gallons (10% of it's weight) at takeoff. When a Thunderbolt met a Jack over Japan, its weight would be much lower, and it's climb rate I would think much higher. Numbers are for example only.

Cheers,
Biff

That's a problem with a LOT of WWII comparisons. The U.S.A. has a lot of data about their planes while some of the basic data about Axis aircraft are seemingly lifted from one website to the next, verbatim. And the lack of things like standard climb from SL to 10,000 and 20,000 feet or a standard metric number of meters makes comparisons difficult and/or almost impossible. If we DO get decent data in some area, then we seemingly fight over fuel quality, etc. I share your curiosity.

I have a P-47N POH and it says the empty weight is 10,998 lbs. and the useful load is anywhere from 2,824 lbs up to 10,200 lbs.

Max fuel internal is 550 US gal. with another 440 US gal. of external fuel possible. So, fuel can run from zero to 990 gallons. So, fuel can run from zero to 3,300 lbs. internally and up to 5,940 lbs if full internal and external fuel is carried. So ... no external and half internal fuel is 1,650 lbs. Pilot is 200 lbs.

It had eight 50-cal MG and COULD carry 500 rpg, but the usual load was 267 rpg.

Clean wing, with racks only, it came in at 16,400 lbs. That included full internal fuel. Since half fuel is 1,650 lbs, the same aircraft at half fuel, still with full ammunition is about 14,750 lbs. Figure we used a little oil and a bit of ammo, and we're looking at 14,300 - 14,500 lbs when about to head for home, assuming that is about when we have half internal fuel remaining.

 

[Clayton Magnet]

Basically what the Japanese had was gun/rocket launcher that with 1/2 the velocity of the German MK 108, fired a bit slower, and a shell that had about 2/3rds of the explosive.
And the magazine held 10 rounds. weapon could empty the magazine in in about 1.25 seconds.

Seems like it was a missed opportunity for a technology transfer, like the U Boat stuffed full of MG 151/20's for the Ki-61 program.
Easier said than done, I suppose

 

[AerialTorpedoDude69]

GregP The optional armament listed in the TAIC manual is confusing and, add to that confusion, it would make sense if an interceptor were well armed. However, 4x12.5mm was what the Japanese Army in 1940 considered to be well armed. At one point, they considered 2x12.5 and 2x7.8mm to be heavily armed as indicated by the Ki-61 and Ki-44-I.

In the J2M vs Ki-44 comparison, one thing worth pointing out is the time frame: These planes are products of the year in which they were designed and manufactured. And I gotta say it's slightly unfair to compare the J2M3 to the Ki-44-II as there is at least a year separating the two. The fairest comparison is to compare the Ki-44-II to the J2M1 as they are both produced in 1942. However, that comparison is when things get weird. Because while the J2M1 had an advanced airframe, its performance lagged behind that of the Ki-44-II although both have similar horsepower, armaments, and armor protection. For whatever reason, the J2M1 weighs substantially more than the Ki-44-II, both in empty and gross weights. (Its gross weight is more comparable.)

And that potentially contributed to the performance gap between the two, despite the Raiden's use of an extension shaft, advanced streamlining, and a "laminar" airfoil. Only the Mustang or maybe the Tempest use so many aerodynamic refinements (although their superlative performance is partly due to their turbo better supercharger. The Ki-44, on the other hand, is a more conventional design, without much attention to detail. So you might think it would perform worse.

But in a head-to-head comparison between the two aircraft, it's surprising that the Ki-44-II cost less to make, performed better, and weighed less while offering the same armor protection and a similar armament.

But so while I appreciate the J2M1's advanced design, we've got to think that something is extremely wrong with the way the Japanese calculate VMAX on their aircraft. Because these two aircraft had approximately equal horsepower ratings at altitude and ended up with the Raiden (Mk.1) being substantially slower than the Ki-44-II. That doesn't make any sense to me. By the way, thanks for your head-to-head comparison between the two aircraft. It helped summarize the differences between the two aircraft.

 

[tomo pauk]

Only the Mustang or maybe the Tempest use so many aerodynamic refinements (although their superlative performance is partlye due to their turbo).

There is no turbo on Mustang, nor on Tempest.

 

[GregP]

GregP The optional armament listed in the TAIC manual is confusing and, add to that confusion, it would make sense if an interceptor were well armed. However, 4x12.5mm was what the Japanese Army in 1940 considered to be well armed. At one point, they considered 2x12.5 and 2x7.8mm to be heavily armed as indicated by the Ki-61 and Ki-44-I.

In the J2M vs Ki-44 comparison, one thing worth pointing out is the time frame: These planes are products of the year in which they were designed and manufactured. And I gotta say it's slightly unfair to compare the J2M3 to the Ki-44-II as there is at least a year separating the two. The fairest comparison is to compare the Ki-44-II to the J2M1 as they are both produced in 1942. However, that comparison is when things get weird. Because while the J2M1 had an advanced airframe, its performance lagged behind that of the Ki-44-II although both have similar horsepowers, armaments, and armor protection. For whatever reason, the J2M1 weighs substantially more than the Ki-44-II, both in empty and gross weights. (Its gross weight is more comparable.)

And that potentially contributed to the performance gap bteween the two, despite the Raiden's use of an extension shaft, advanced streamlining, and a "laminar" airfoil. Only the Mustang or maybe the Tempest use so many aerodynamic refinements (although their superlative performance is partlye due to their turbo). The Ki-44, on the other hand, is a more conventional design, without much attention to detail. So you might think it would performance worse.

But in a head-to-head comparison between the two aircraft, its a bit surprising that the Ki-44-II cost less to make, performed better, and weighed less while offering the same armor protection and a similar armament.

But so while I appreciate the J2M1's advanced design, we've got to think that something is extremely wrong with the way the Japanese calculate VMAX on their aircraft. Because these two aircraft had approximately equal horsepower ratings at altitude and ended up with the Raiden (Mk.1) being substantially slower than the Ki-44-II. That doesn't make any sense to me. By the way, thanks for your head-to-head comparison between the two aircraft. It helped summarize the distinction between the two aircraft.

Hi AerialTorpedoDude.

Somehwat agree, but neither the Mustang nor the Tempest had a turbosupercharger, They were supercharged and, in the case of the P-51D, a 2-stage unit. The Sabre-powered Tempest V had a single-stage, 2-speed supercharger. The Centaurus powered Tempest also had a single-stage, 2-speed supercharger.

An empty Radien comes in at about the normal gross of the Ki-44. That much extra weight without a corresponding power increase accounts for the early performance of the Raiden. Nothing like power to help performance, is there?

 

[BiffF15]

That's a problem with a LOT of WWII comparisons. The U.S.A. has a lot of data about their planes while some of the basic data about Axis aircraft are seemingly lifted from one website to the next, verbatim. And the lack of things like standard climb from SL to 10,000 and 20,000 feet or a standard metric number of meters makes comparisons difficult and/or almost impossible. If we DO get decent data in some area, then we seemingly fight over fuel quality, etc. I share your curiosity.

I have a P-47N POH and it says the empty weight is 10,998 lbs. and the useful load is anywhere from 2,824 lbs up to 10,200 lbs.

Max fuel internal is 550 US gal. with another 440 US gal. of external fuel possible. So, fuel can run from zero to 990 gallons. So, fuel can run from zero to 3,300 lbs. internally and up to 5,940 lbs if full internal and external fuel is carried. So ... no external and half internal fuel is 1,650 lbs. Pilot is 200 lbs.

It had eight 50-cal MG and COULD carry 500 rpg, but the usual load was 267 rpg.

Clean wing, with racks only, it came in at 16,400 lbs. That included full internal fuel. Since half fuel is 1,650 lbs, the same aircraft at half fuel, still with full ammunition is about 14,750 lbs. Figure we used a little oil and a bit of ammo, and we're looking at 14,300 - 14,500 lbs when about to head for home, assuming that is about when we have half internal fuel remaining.

GregP,

First, thanks for the info. To be more specific what I'm looking for is the performance of a P47N at weights it would have seen over Japan on a mission with an expected over water RTB. The numbers I keep seeing don't seem to line up with that weight / configuration. I would think the P47N would perform quite a bit better due to shedding tanks, fuel, and water injection before or as the fight develops. The Mustang Me109 comparisons seem to use takeoff weights / speeds / climb rates when in actuality the Mustang engaging Fw's and Me's over Berlin would be much lighter having shed a larger portion of it's weight / drag from jettisoning tanks and burning gas (a greater improvement in it's performance than the aircraft it encounters). As with the Mustang example, the P47N would be the same at "fights on" over the J2M, Ki-44, or any other Imp Japanese fighter.

Cheers,
Biff

 

[GregP]

Almost all the performance tests are at normal gross weight because that is the worst performance you can expect. I'm pretty sure that as a former F-15 pilot, you saw an enormous difference between an F-15 at airshow weight and an F-15 with full armament and tanks / ordnance. Some even flew with conformal tanks, external tanks, and ordnance, didn't they?

The P-47N performance trials over at wwiaircraftperformace.net show the P-47N with an initial rate of climb of 2,200 fpm at 54.5" Hg and 3,200 fpm at 72: Hg WER. Both of those are at 16,330lbs. I am assuming 2,800 hp WER and about 2,200 HP normal.

I will use a standard formula: RC = (33,000 [(PA-PR)/(W)]), where: RC = rate of climb (fpm), PA =Power available (hp), PR = power required for level flight (hp), W = weight (lbs).

If I punch in 2800 hp and 16,300 lbs for weight, I can back into PR using 3,300 fpm RC. PR would equal 1170 hp. Really, it will be less due to propeller efficiency, etc. Now, if I change the weight to 14,300 lbs, the new rate of climb will be about 3,761 fpm. I am assuming you mean rate of climb since speed would be almost the same. I'd expect roll rate to also not change much with weight, unless the initial roll rate was with wing tanks and the new one is clean.

That's sort of a basic first-order approximation, but shouldn't be too far off. The climb will be better at lighter weights, the question is by how much. A real, practicing aeronautical engineer could do better. Maybe Drgondog will chime in here.

The P-47 has a fantastic zoom climb due to weight and a nice climb boost with reduced weight. It was also a decently fast roller.