The KI-84-IB

[Krusty]

Ki61 v. Ki100 stats...

Category: value (Ki61) | value (Ki100) Bold will be the better of the 2.

LOADED WEIGHT: 7,650 lb | 7,705 lb
Drag: inline slim profile | wide round radial
Service Ceiling: 11,600 m | 11,000 m
Top speed: ~375 mph as modeled in AH @ 15k | 360mph @19.7k
 

Currently the AH model for the Ki-61 is off... It should turn as well as the wildcat, but does not. That said the only reason they put a heavy, fat, lead slug of an engine in the nose was because they had airframes sitting around in wartime with no engines. It was an act of desperation. Crews enjoyed radial engines. It was a cultural experience with their armed forces that radial engines were reliable and trustworthy. The performance was 99% identical to the Ki-61 except that the power curve looked a little different. The speeds were just about the same, but they just had a dog-leg in the chart like the A6M5 engine does.


The only benefit the Ki-100 would have is the climb rate. It would be MARGINALLY better (probably a couple hundred fpm if that) because the plane had more horsepower. This was offset in normal flight by the drag and weight (so don't expect massive acceleration), but at climb speeds I think it means a little extra climb rate. Time to 15000 listed as 6 minutes to the 7 minutes of the Ki61. Some estimates at low-3000s (one said 3200, not sure, most don't say on the Internet) feet per minute, whereas our Ki61 does 3000 and our Ki84 does about 4000-4200fpm.

 
There is almost no area of the Ki-100 that the Ki-61 doesn't do or do better, except fly at 19.7k, and the Ki61 will be much faster at 15k where most other Japanese engines are at their weakest power drop.

I repeat: It was a lack of engines, not a boost in performance, that spawned this joining of parts. There are tons of propaganda out there claiming it was the best ever, it killed 12 hellcats on its first mission, etc etc... None of these are true. It was simply a Ki61 with a different engine and performed exactly the same but with a better maintenance record.


As for the Ki-84-IIb, I find these rapid-fire 20mms the equal of hispanos -- not in overall boom per round, but for the lethal 1-burst-kill capabilities... More than once I've had something fly through my stream of quad typh/temp/chog/hurr2 guns and shrug it off (when the same guns mounted 2x on a spit would insta-kill?? Makes no sense!!!), whereas if I land a solid ping with a Ki-84 it usually does plenty of damage. I really like the Ki-84 guns. You can blow your ammo really fast without a bit of self restraint, but when you have a shot and you take it, they get the job done and THEN some!

[nrshida]

Krusty, you have asserted once in this thread that the Ki-100 = Ki-61, and previously (5 years ago in fact) that the Ki-100 would perform worse than the Ki-61:-

http://bbs.hitechcreations.com/smf/index.php/topic,164462.0.html

I do not argue with your explanation for the circumstances of the Ki-61 to Ki-100 conversion. This is well documented. Nor do I dispute that the Ki-100 likely took a small penalty on top speed due to larger frontal area.

However can you please cite your reference for the data you have posted above regarding the comparable weights of the Ki-100 / Ki-61 variants.

You are the only one who claims the weights were anywhere near similar. In fact you state a weight gain of 55lbs going from Ki-61 to Ki-100.

Every other source of information I read indicates a considerable weight SAVING going from the liquid-cooled V12 to the air / oil-cooled radial. Depending on where you read, the saving was from 100 - 300 kgs (approx 220 - 660lbs).

You refer to the radial as a 'heavy, fat, lead slug of an engine in the nose' but the radial engine alone was apparently lighter than the V-12 engine. The nose was also 5 inches shorter, if that is relevant. On top of that the liquid cooling system was not present. No radiators, hoses, pumps, valves or the actual liquid either. Several versions of the Ki-61 also had a lead counterbalance in the tail, fitted to offset the increasingly heavy Ha-140 engine during production. This was also removed to restore the centre of gravity in the Ki-100.

So how can what you have stated be so? Please account for the additional mass.

Secondly while you mention that the Ki-100 had more power, there was in fact a considerable gain in power moving to the radial engine. It seems to be agreed that the Kawasaki Ha-40 inverted V12 liquid-cooled engine was rated around 1,175 bhp. While the Mitsubishi Ha-112-II 14 cylinder radial engine was rated at approximately 1,500 bhp.

If the above data is correct, and stated simply for clarity: more power AND less weight, then while absolute top speed might be lower, surely general handling, climb rate, turn rate and acceleration would be markedly improved. This would be in keeping with the Imperial Japanese Army's findings regarding the flight characteristics of the Ki-100, which they claim surpassed the Ki-61's in all but maximum speed.

Perhaps JHerne would be kind enough to consult his library for us and cite some definitive references regarding the comparable weights and power outputs of the Ki-61 and Ki-100?

[STEELE]

+1 to the 1B and toss in the 1C, or just do the 190A8 thing n make 3 guns packages

[Krusty]

Radial engines often have more horsepower than inline engines in planes with similar performances... The horsepower alone doesnt equate to great performance when it is totally negated with excessive drag and weight.

Look at USN planes and how much horsepower they have vs similar performing planes with Allison engines, or Merlin engines.

More horsepower in a radial doesn't mean much when it's got a massive flat surface it had to drag into the wind.

The weights were pulled from wiki for simplicity's sake. Typical loaded weights. I dislike comparing empty weights because often those are very misleading (and in the Fw190 weight debate many sources came up that considered different "loadouts" as "empty" -- but they all agreed on typical loaded weight)

More horsepower != better speed, if the horsepower is gained from switching from inline to radial.

[HighTone]

Would like to see the Ki-81-Ib. I love the Ki-84 and have been flying it as almost my primary ride for a few months now. And while I do agree that the .50's are enough, the 4 x 20mm Ho-5's would give a better punch for bombers and other heavily armoured aircraft. Plus just another choice is always great.

One thing though, the Ki-84-Ib had slightly more horsepower than the Ia. The Ib rated at 1990 hp at take off vs the Ia at 1900 hp. Hopefully that would help offset the additional weight of the extra cannons. Also I believe that on the Ib the cannons in the nose had 100 rounds per gun, while the wing cannons stayed the same at 150 rounds per gun.

That would be sweet, the Ki-84-Ib with 1990 hp, and 4 x 20mm Ho-5 cannons with 500 rounds total.

The Ic, well that would be nice, but with the same engine as the Ib, we could just add it as a gun package.

Of course out of all this, I still think we need the Ki-43(II) and Ki-44 first. Also the G4M, J2M3 and the Ki-45 

[JHerne]

Here's my references pertaining to the Ki-61/Ki-100

Aerodetail 23 Ki-100
ModelArt 428 IJA Kawasaki Type 3 & Type 5 fighters
ModelPress 4 Ki-100
Famous Airplanes of the World #23 Ki-100 Type 5 Fighter
Japanese Military Aircraft of WWII
Kagero Miniatury Lotnicze 23 - 68th Sentai

In most cases, you're going to have to brush up on either your Kanjii or Czech. In most of these books, performance data is listed, and in a few, comparative data against US types is provided. Ironically, not one of these publications considers the Ki-61 to an equal of the Ki-100.

J

[nrshida]

Krusty, the point about the top speed was conceded by everyone present, including the Imperial Japanese Army.

However, there you go again with your excessive weight claim. Just because the engine looks bigger does not make it heavier. On Wikipedia, which I believe was the source you yourself cited ('wiki'?), it claims the Mitsubishi Ha-112 radial to be 54 kg (120lbs) lighter than the Ha-140 V12. That's just for the engine unit alone.

Empty weights or loaded weights are not misleading as long as you compare like with like. Wikipedia, if indeed it can be relied upon at all, also has a brief specification for both the Ki-61 and the Ki-100, empty weight and loaded weight for both aircraft, if you would care to check.

Further, the frontal area in fact is not massively flat as you imply, take a look at the photos I posted. There is a streamlined cowling and some of the air is directed over the cylinders and heads and expelled rearwards.

Comparing a Vought Corsair to a Spitfire, for example, is quite another thing to comparing the same airframe with a radial engine fitted. If you stood next to the Ki-100 you would see what I mean, the aircraft is apparently no larger than the Bf109G-2 trop that is one plane further along. Another famously small fighter aircraft.

Regardless of your unique and persistant claim regarding the Ki-100 being equal to the Ki-61, the power output of the Ki-100 is historically documented as being much higher than the Ki-61, and the weight of the Ki-100 conversely documented as being much lower.

Respectfully I suggest you have perhaps gathered your data from an unreliable source.

Regarding the IJA's claims of improved performance in all other areas. Improved turning would come alone from a reduction in mass. Improved climb from a reduction in mass and an increase in power. Finally acceleration, if my understanding garnered from several detailed technical posts by Stoney, BadBoy and HiTech does not fail me, could also be improved at lower speeds by virtue of lower parasitic drag and higher relative propellor thrust and yet further increased by virtue of the more powerful engine?

Hopefully a mathematician will be along shortly to straighten us all out.

[Krusty]

No need for math nshida... Simple historical performance facts are available.

This has been hashed and rehashed many many times. I believe WideWing put it very nicely once:

Basically, the Ki-100 was terribly slow when compared to what it had to compete with.

Let's see how it compares to a P-40L of 1942.

Speed
P-40L: 370 mph at 20k
Ki-100: 360 mph at 19.8k

Sea level speed
P-40L: 312 mph
Ki-100: 307 mph

Climb, initial from sea level
P-40L: 3,300 fpm
Ki-100: 3,200 fpm

Time to climb
P-40L: 5.9 minutes to 15k
Ki-100: 6.6 minutes to 16.4k

Very similar performance, except that the P-40L entered service in 1942 and the Ki-100 in 1945.

Facing the Ki-100 was the F6F-5, F4U-1D, F4U-4, P-51D and P-47N.

The slowest of these is the F6F-5, which when tested by TAIC attained 409 mph at 21,600 feet (that's 6 mph less than Grumman claimed). At 20k, the Ki-100 can manage only 349 mph, at 21.6k it will be slower still.

The other American fighters were faster yet. How would the Ki-100 hope to compete? Consider that the A6M5 easily out-climbed the Ki-100 and could turn circles around it, the only advantage of the Ki-100 was in speed, and that advantage was less than 20 mph. By 1945, the Zero was hopelessly out of date. Granted, the Ki-100 was easy to fly, meaning low-time pilots could fly it without difficulty. Handling was excellent, but like the Ki-61, its initial and sustained rate of roll was barely average, degrading from 240 mph on up. Acceleration was poor, especially by late-war standards.

In short, the Ki-100 was a solid fighter for 1942, but by 1945 it was completely out-classed. It could and did score victories. But, so did the Zero.

As to sources, I'd avoid most of the books written by pulp factory authors like Gunston. Joe Baugher uses Francillon as a source and Francillon published more fiction than Stephen King...

Indeed, the utter hogwash of Ki-100s matching the P-51D and P-47N is rediculous in the extreme. That claim of 14 F6Fs shot down for no loss was a complete frabrication, unsupported by Navy records. Yet, author after author repeats this nonsense over and over.

The battle these idiots are referring to occured on July 25th, 1945 over Yokaichi Airfield. 18 Ki-100s bounced a group of 10 Hellcats. The Japanese were at 12,000 feet, the F6Fs were down around 5,000 feet, strafing and rocketing the base. In the ensuing fight, two F6Fs were lost. One in a collision with Captain Tsutae Obara. Both pilots were killed. Ensign Herbert Law's engine was hit by ground fire, causing the windscreen to obscured by engine oil. Unable to see, he evaded long enough to crash-land his Hellcat. IJAAF Warrant Officer Shin Ikuta was shot down and killed by the F6Fs. Low on gas and ammo, the remaining 8 Hellcats returned to their carrier. Japanese pilots claimed 12 F6Fs destroyed. Navy pilots claimed 8 Japanese aircraft shot down or destroyed on the ground. Actual losses were 2 lost and 2 damaged for the Americans. Japanese losses were 2 lost and 3 damaged, one of which crash-landed on Yokaichi field. Several Japanese aircraft were left burning on the field resulting from the Hellcats strafing. Gun camera film revealed that 3 utility aircraft had been set ablaze by the F6Fs, and several more unidentified aircraft were damaged to some extent.

Over time, this engagement has been embellished to inflate the Japanese claims and ignore the fact that two Ki-100s went down and another shot-up Ki-100 was wrecked in a forced landing.

In reality, the Japanese force, nearly twice as large as the American force, attacked with the advantage of altitude. Despite being handed a significant disadvanage, the Navy pilots scored as well or better than the Japanese and were able to disengage at will.

Virtually anything written by Henry Sakaida can be trusted to be generally correct. Watanabe is also reasonably reliable, with Kuroe, Jobo and Izawa somewhat less so. Some of these authors accept Japanese claims on face value, therefore it is essential to compare US records to get an accurate picture. However, all the the above can be relied upon to accurately report Japanese losses. Look for english translations as much of the material by the above authors was published in the Japanese language.

My regards,

Widewing

Please note it performs worse than a 1942-era P-40L but first saw combat in 1945, and did rather poorly at that. Waaaaay too much revisionist history and BS revolving around the Ki-100's uberness.

[Doc72]

Did the -B see combat?

Yes it did.....it wasn't very long at all after the A came out that the B came into play with the 4-20mm's.

[Krusty]

On the subject of the -B, Doc do you actually have some reference to show the 4x20mm saw combat? I've been curious as records of this are sketchy at best.

[nrshida]

Krusty, surely not the straw man approach. Our disagreement was over the statistics you posted and your assertion that the Ki-100 = Ki61. Which was unsupported by all other sources.

I agree that the Ki-100 was born out of desperation by the Japanese manufacturers and also that the top speed was lower than the Ki-61. I also agree with Widewing that the famous combat report with the Hellcats has been discredited. We don't suggest 'uberness' and don't even ask for 'uberness'.

The fans of the Ki-100 would like to see it included because by all accounts, although it's top speed was slower, it was essentially a better handling, better turning and better climbing derivative of the Ki-61. It was an interesting and resourceful piece of engineering, and it did fly in combat in the defense of Japan.

I think your implication that top speed is some metric for the 'uberness' of an aircraft is rather missleading, at least in the context of Aces High. If that was so then surely (for example) the Brewster Buffalo would never leave the hanger?

I don't agree that an aircraft should be ruled out for inclusion on the grounds that more 'competitive' aircraft should be added instead.

[Perrine]

No need for math nshida... Simple historical performance facts are available.

This has been hashed and rehashed many many times. I believe WideWing put it very nicely once:

Is the quoted speed for  ki-100 at deck in military or wep power?

[Wmaker]

nrshida,

You are comparing the weights between Ki-61-II and Ki-100. Ki-100 was indeed lighter than the Ki-61-II but weighed almost the same as the KI-61-I-Tei we have in AH (source: AH/Francillon). The AHs weight agrees to the pound with Francillons (he's still a quite credible source on many issues, albeit the research is old and not without errors) figure for the Ki-61-Kai c, which, AH Ki-61 was named initially in AH until a Japanese player wanted the name change to more accurately match the designation to the Ki-61 AH has.

So the Ki-100 and AH's Ki-61 weigh about the same but Ki-100 puts out approx 320hp more. So yes, considering the better power loading and practically the same wingloading, it should perform clearly better than the Ki-61 we have in AH. I also think that 320hp goes quite a long way to offset the radial's drag regards to absolute top speed performance. Obviously, it would still be far, far inferior to any 1945 USN/USAAF fighter that it had to face but it would indeed be a fun ride here in AH, where the realities of the real war rarely match the arena-play.

[nrshida]

Thank you Wmaker, I'm sorry to differ with you but you have stated one thing incorrectly. I actually didn't find any data regarding the Ki-61-II. The weights I found pertained to the Ki-61-I-KAIc. I do not know how similar this is to the KI-61-I-Tei we have in Aces High. I am now searching...

I do not have a copy of that book myself, but actually Francillon is cited as the source for the specifications on Wikipedia.

If you have this book, or anyone else does, would you be so kind as to check that the information on Wikipedia is faithful to the printed data. In fact, if you have the means and it is allowed, would it be possible to upload some scans of the relevant pages? Especially if there is any data regarding the KI-61-I-Tei (AH version).




From Wikipedia:-




'Japanese Aircraft of the Pacific War', pages 119-120:-

Specifications (Ki-61-I-KAIc)

Powerplant: 1× Kawasaki Ha-40 liquid-cooled inverted V12 engine, 875 kW (1,175 hp)

Length: 8.94 m (29 ft 4 in)
Wingspan: 12.00 m (39 ft 4 in)
Height: 3.70 m (12 ft 2 in)

Wing area: 20.00 m² (215.28 ft²)

Empty weight: 2,630 kg (5,800 lb)
Loaded weight: 3,470 kg (7,650 lb)
Range: 580 km (360 mi)




'Japanese Aircraft of the Pacific War', pages 133–134:-

Specifications (Ki-100-1a/b Goshikisen)

Powerplant: 1× Mitsubishi Ha 112-II radial engine, 1,120 kW (1,500 hp) at take off

Length: 8.82 m (28 ft 11 in)
Wingspan: 12.00 m (39 ft 4 in)
Height: 3.75 m (12 ft 4 in)

Wing area: 20 m² (215 ft²)

Empty weight: 2,525 kg (5,567 lb)
Loaded weight: 3,495 kg (7,705 lb)
Range: 2,200 km (1,189 nmi, 1,367 mi)




Assuming the above data is correct, then the differences between loaded weights give a very misleading picture. One thing jumped out at me immediately, look at the comparative ranges of the aircraft. In fact the range information must surely be an error. An increase by a factor of about 3.7? I think it's unlikely. Regardless, the unloaded weights paint a very different picture. Assuming that unloaded only refers to no fuel and no ammunition?

I propose the only logical explanation is that the Ki-100 must have had an additional fuel tank fitted. Perhaps in front of the cockpit, the space where the new steel engine support frame is located? I did comment previously on the importance of comparing like with like. Obviously fully loaded with fuel does not give an equal comparison if the latter had a larger capacity. I am now searching for pictures to see if this is so.

Could this be the source of the continued confusion I wonder?

Sorry to keep banging on about it, I do feel sorry for the original poster who's thread we have now completely derailed. I did suggest starting a Ki-100 thread earlier. I'm only trying to find and establish quantifiable facts.

Must I actually go back to the R.A.F. Museum with a large screwdriver and 3 sets of industrial grade bathroom scales? Sheesh the things you have to go through to put a 'Thank you for the Ki-100 HTC!' in your signature. 

[Wmaker]

Hi nrshida!

I started a new thread about the Ki-61/Ki-100 over at A&V forum: http://bbs.hitechcreations.com/smf/index.php/topic,297618.0.html