Thoughts on the Nakajima Ki-84 and Kawasaki Ki-100

GregP said:

Doesn't weigh much? Overload for long range is over 11,000 pounds!

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Where do you get this weight from Greg? I've only seen figures below 8,000 lbs fully loaded for the Ki-100.

GregP said:

Have to disagree with this post. The Ta 152 and Spitfire XIV were never true contemporaries of the Ki-48/100. These airplanes (Ta 152 and Spitfire XIV) fought in the ETO and never made an appearance in the PTO during the war. Contemporary in time, sure. Contemporary in combat, no.

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My original post was in regards to the Ki-100 specifically, not the Ki-84. I used the Spitfire Mk.XIV as an example of an aircraft in service at the time of the Ki-100's introduction, but it was not really a contemporary in time either, as it entered service more than a year previous. A more accurate Spitfire to use would be the Mk 21, which entered service about about a month before the Ki-100.
I quite like the Ki-100, however, for an aircraft entering service in 1945, it did not have impressive performance, maybe on par with other Japanese fighters that entered service years before, like the J2M and Ki-44.
I think the Ki-100's true value, was that it was available, and perhaps most importantly, RELIABLE.

Actually, DarrenW, I'm talking about restored pristine, new-looking examples of both the F6F and the F4U, usually an F4U-1a or F4U-1d.

They fly side by side at identical power and rpm settings. This from current pilots who fly them. Now, nobody is doing WER runs, but they ARE cruising them side by side at the same power settings. What this tells me is they are not that different aerodynamically at cruise power settings. It doesn't tell me what they will do at max power side by side.

Here is a routine where the Horsemen (Jim Beasley and Ed Shipley) are flying a P-51D and an F4U Corsair. This does NOT show they are flying at equivalent power settings (and they aren't), but does show they have no trouble flying side by side.

Just because it sort of fits with my last post, here are the Horsemen in F-86s, with Steve Hinton in lead, Ed Shipley and Dan Friedkin on wing.


This is from the Planes of Fame Airshow in 2012.

NAA sure built pretty airplanes.

I hear you Greg and I fully agree that aerodynamically there wasn't a lot to choose from between the two but the Corsair was STILL the 'cleaner' aircraft, with a smaller total drag figure and wing area to boot. A very fast radial engine carrier fighter was what Vought was shooting for afterall and they definitely got it. On the other hand Grumman made the Hellcat to be as simple as possible to fly off a carrier, fast enough to deal with the Japanese, and easy to manufacture. They were only concerned about aerodynamics to a certain extent. They obviously played their cards right and built a real winner of a fighter plane.

My point is that while there may be less of a difference in throttle settings at slower speeds, the aerodynamic disparity between the two becomes more and more apparent the faster you fly. So yes in a CRUISE the settings between the two may be very close but this won't last long as throttles get advanced.

And although I can fully appreciate and respect first hand accounts from the pilots who currently fly them, without knowing the configuration of each and "correctness" to original factory built aircraft it's really difficult to assess if what they now claim was actually the case during the war.

Would I be correct in saying that the A6M that the Planes Of Fame Museum in Chino, California has, is actually the closest we could ever hope to get to testing an actual WW II warbird?
A couple of vaguely 20 mm cannon shaped weights and a couple of vaguely .30 cal. machine gun shaped weights. Self sealing gas tanks, pilot armor, what's that? Radio? Ya' got a hand-held, right?

Hi SparotRob,

The Planes of Fame A6M5 Model 52 is VERY authentic to original drawings.

The main differences would be:

1) The pilot's seat has been moved aft by about 6 inches to accommodate larger pilots.
2) The original pinned-in-the-middle rudder bar has been replaced with a rudder pedal assembly from an F8F Bearcat, so the rudders move fore and aft instead of pivot in the middle. Therefore, brakes are toe brakes, not heel brakes.
3) There are some SAE bolts that have replaced originals metric bolts. Not all have done so but, if they have a problem with a metric bolt, it is very likely an SAE bolts is substituted. There is no "metric phobia," but metric AN bolts are more than twice the cost of SAE AN bolts and there is NO reason to pay more for an already-too-expensive aircraft repair or overhaul. When metric bolts come down to reasonable prices, if ever, then they'd likely go with original-size metric hardware.
4) There is a modern radio and an ADSB.
5) The original main landing gear doors are missing and they fabricated some good-enough flatter doors to fly with. There is some interest in making a set of original type gear doors, but they are complex forms and not at all simple constructs. They'd likely be very simple if they had the original forms for the gear doors, but they don't. It would likely not be worth the effort to fabricate doors to the original drawings for anyone but a dedicated purist who has the money and time to throw at it.
6) The armament has been removed and replaced with dummy units, as in ALL civilian aircraft expect for maybe one fully-armed P-51D Mustang that might be flying about in some unnamed country somewhere.
7) Some original skin has been replaced when it was corroded or damaged.
8) New fabric was installed several years back. I removed the old fabric from the ailerons, elevators, and rudder myself since I was working for Steve Hinton at the time. But that fabric was also not original ... it came from the original restoration back in 1976 - 77. The rudder trim adjust mechanism is a wonder of simplicity and very tight operation ... there is no slop in the trim mechanism.
9) The internal cable controls are all new with new pulleys. This was done several years back during the major overhaul that was completed. The engine did not require an overhaul and is in great condition, as is the spare engine.
10) The propeller is original and is a Sumitomo unit supplied to Mitsubishi under license that is identical to a Hamilton-Standard unit. Japan had a legal license to manufacture these propellers before the war and the war didn't change the license for manufacture.
11) Several instruments are modern English-unit instruments. Some are original. The throttle still has the selector switch that allows the pilot to select MG, cannons, or both.
12) The aircraft has a modern ELT.
13) The tires are modern tires that are the original size. The tailwheel is solid, not pneumatic, as it was in original manufacture.

Close enough!

DarrenW said:

I hear you Greg and I fully agree that aerodynamically there wasn't a lot to choose from between the two but the Corsair was STILL the 'cleaner' aircraft, with a smaller total drag figure and wing area to boot. A very fast radial engine carrier fighter was what Vought was shooting for afterall and they definitely got it. On the other hand Grumman made the Hellcat to be as simple as possible to fly off a carrier, fast enough to deal with the Japanese, and easy to manufacture. They were only concerned about aerodynamics to a certain extent. They obviously played their cards right and built a real winner of a fighter plane.

My point is that while there may be less of a difference in throttle settings at slower speeds, the aerodynamic disparity between the two becomes more and more apparent the faster you fly. So yes in a CRUISE the settings between the two may be very close but this won't last long as throttles get advanced.

And although I can fully appreciate and respect first hand accounts from the pilots who currently fly them, without knowing the configuration of each and "correctness" to original factory built aircraft it's really difficult to assess if what they now claim was actually the case during the war.

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Corsair has smaller wing area? I don't think so. The Ki-84 is overall a smaller airplane with the same horsepower as the Corsair.

An F4U-4 comes in at 9,200 lbs empty and 14,670 lbs gross. It has 314 square feet of wing area. The engine has 2,380 hp WER. That is 6.16 lbs/hp.

A Ki-84 I-a comes in at 5,864 lbs empty and 7,940 lbs gross. It has 230 square feet of wing area. The engine has 2,041 hp at sea level. That is 3.89 lbs/hp. It also has 3 feet more wingspan than a Corsair. It SHOULD be a bit better at higher altitude due to better span loading.

The Ki-84 is lighter at gross than an F4U-4 is empty! And the horsepower is very close. The Ki-84 at gross has a power loading that is HALF that of a gross weight Corsair. Sorry, the supposed lack of performance for the Ki-84 just doesn't add up ... but that's just my take on it.

But ... I also don't want to fight about it. Here is my drawing of a Ki-84:



I think it was the best Japanese piston fighter by a decent margin when everything in the aircraft was working. If everything isn't working right, you pays your money and you takes your chances.

GregP said:

Corsair has smaller wing area? I don't think so. The Ki-84 is overall a smaller airplane with the same horsepower as the Corsair.

An F4U-4 comes in at 9,200 lbs empty and 14,670 lbs gross. It has 314 square feet of wing area. The engine has 2,380 hp WER. That is 6.16 lbs/hp.

A Ki-84 I-a comes in at 5,864 lbs empty and 7,940 lbs gross. It has 230 square feet of wing area. The engine has 2,041 hp at sea level. That is 3.89 lbs/hp. It also has 3 feet more wingspan than a Corsair. It SHOULD be a bit better at higher altitude due to better span loading.

The Ki-84 is lighter at gross than an F4U-4 is empty! And the horsepower is very close. The Ki-84 at gross has a power loading that is HALF that of a gross weight Corsair. Sorry, the supposed lack of performance for the Ki-84 just doesn't add up ... but that's just my take on it.

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Greg please re-read my post. I was obviously comparing the F4U with the F6F and NOT the Ki-84.

Duhhh ... OK. I was looking at the Ki-84 in the topic heading after doing something else that required some thinking. Open mouth, insert foot, chew. Cheers.

Maybe it was placing all those rivets in the drawing that did it ...

GregP said:

Duhhh ... OK. I was looking at the Ki-84 in the topic heading after doing something else that required some thinking. Open mouth, insert foot, chew. Cheers.

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No problem. I still enjoyed reading your post. It's filled with losts of great information!

I check in here now and then, and do other things in between, so sometimes it is hard to stay on topic. I was just looking at installing a GFCI / AFCI receptacle in the back yard and was doing a load calculation for the circuit. It isn't exactly rocket science, but it does make an old guy think a bit.

GregP said:

Sorry, the supposed lack of performance for the Ki-84 just doesn't add up ...

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Probably because it was better on paper than in actual service. Most engines didn't produce nearly the horsepower as designed, and sub-par maintenance practices took their toll on war-weary airframes.

Furthermore, athough there exists that oft-quoted remark about not bothering to intercept Franks at high altitude because of their speed, there are other reports which describe the Ki-84 as faster than your average Zero but not terribly difficult to catch and shoot down. Author Richard M. Bueschel stated that some were hard pressed to reach even 250 mph due to engine and airframe issues.

GregP said:

Sorry, the supposed lack of performance for the Ki-84 just doesn't add up ... but that's just my take on it.

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I don't think anyone in this thread has claimed the Ki-84 had relatively low performance. That claim has been reserved for the Ki-100

GregP said:

I check in here now and then, and do other things in between, so sometimes it is hard to stay on topic. I was just looking at installing a GFCI / AFCI receptacle in the back yard and was doing a load calculation for the circuit. It isn't exactly rocket science, but it does make an old guy think a bit.

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Yep, I know that all too well myself!

Just Schmidt said:

Honestly I think the Ki 100 is overrated. Sure, it dived well, had a reliable engine and handled well, indeed seem to have been a forgiving airplane. But if the performance figures we have is anything to go on, something in the area of 580 km/h is not going to cut it for a fighter entering service in 1945. I really don't think it can be compared to the Ta-152, though they did try to make it into a high attitude fighter. They did not approach reliability in that role. It was not bad for its 1500 hp radial, and it was an impressive enough feat of engineering to convert it in so little time.

Add to that the overwhelming number of aircraft the allied possessed.That inexperienced pilots could fly it is a mixed blessing, these pilots may have been better served with not having an aircraft at all. I think I've said something along these lines before.

The Ki 84 was plagued by an unreliable engine, and decreasing standards of production didn't help. IIRC it at least initially had problems with collapsing undercarriage. The performance figures I've seen range between app. 630 km/h and 690 km/h. Not enough to set a world record, but quite decent. it entered service long before the Ki 100. Some may not have had a homare that delivered as much as 1500 hp, but I think it was a match for the best upon entering service. Of course it was outnumbered too, though far more were produced. While the unluckier individual examples may have performed no better (or even worse), it was always potentially a superior aircraft, and often so in practice too.

Of course better fuel would help both of them.

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I'm always left shaking my head when I see the horsepower ratings of Japanese engines. Does anyone know of a reference dealing primarily/solely with Japanese aircraft engines?

Just Schmidt said:

Honestly I think the Ki 100 is overrated. Sure, it dived well, had a reliable engine and handled well, indeed seem to have been a forgiving airplane. But if the performance figures we have is anything to go on, something in the area of 580 km/h is not going to cut it for a fighter entering service in 1945.

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Japanese figures are moderately better. More like 600 - 605 kph depending on the batch of airframes. I believe the 580 kph figure is for the Western equivalent of maximum continuous power, and the 600 kph + figure is with full water/methanol injection.

That's still very far from world beating. The 109F-1 was making that sort of speed in very late 1940/very early 1941!

The thing about the Ki-100 was that all reports make it out to be an absolute delight to fly - very little workload for the pilot, easy handling, superior maneuverability to anything bar a Ki-43-II across the speed range, able to dive to high speeds and with solid build quality/reliability (not something to be underestimated in Japan in early 1945).

This make it just the sort of aircraft that Japanese Army pilots liked - which is why it's reputation is probably so good from a Japanese PoV.

GregP said:

There is no "metric phobia," but metric AN bolts are more than twice the cost of SAE AN bolts and there is NO reason to pay more for an already-too-expensive aircraft repair or overhaul. When metric bolts come down to reasonable prices, if ever, then they'd likely go with original-size metric hardware..

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Hi Greg
WAAAAAYYYY back when I was doing the MiG certifications I found that Aviall Germany had metric hardware and hose fittings at about the same price delivered in Aus as the AN/MS/NAS hardware was here. Was also actually a lot cheaper than using hashed up non-aviation hose fittings like a competitor used and required no ADR approval (like Form 337 in USA but requires a full engineering analysis and certification.

And in the earlier F-86 post - Steve snr or jnr?