Ki-61/100 Hien Performance

[Laurelix]

Ki-61-I Ko / Otsu / Hei
Empty Weight: 2380kg
Loaded Weight: 3130kg
Wing Area: 20m2
Engine: Ha-40
Take Off: 1160hp (WEP)
1030hp at SL / 1085hp at 4200m
-
Max Speed: (Military Power) [Mannifold Pressure]
Sea Level: 471kph [39Hg]
1000m: 496kph [39Hg]
2000m: 520kph [39Hg]
3000m: 545kph [39Hg]
4000m: 569kph [39Hg]
4760m: 588kph [39Hg]
5000m: 589kph [38Hg]
6000m: 591kph [34Hg]
7000m: 589kph [30Hg]
8000m: 580kph [26Hg]
9000m: 561kph [23Hg]
10000m: 523kph [20Hg]
-
Rate of Climb: (Military Power)
Time to 5000m: 5:30
Time to 8000m: 10:48
-
Stall Speed: (No Flaps, 1000m, 3130kg Weight)
150km/h IAS
-
Armament:
Ko:
2x 7.7mm Type 89
2x 12.7mm Ho-103
-
Otsu:
4x 12.7mm Ho-103
-
Hei:
2x 12.7mm Ho-103
2x 20mm MG-151
-
Sustained Turn Time: (WEP, Sea Level)
16 Seconds

—————————————

Ki-61-I Tei
Empty Weight: 2630kg
Loaded Weight: 3470kg
Wing Area: 20m2
Engine: Ha-40
Take Off: 1160hp (WEP)
1030hp at SL / 1085hp at 4200m
-
Max Speed: (Military Power)
Sea Level: 462kph
5000m: 580kph
-
Rate of Climb: (Military Power)
Time to 5000m: 7:00
-
Stall Speed: (No Flaps, 1000m, 3470kg Weight)
158km/h IAS
-
Armament:
2x 12.7mm Ho-103
2x 20mm Ho-5
-
Sustained Turn Time: (WEP, Sea Level)
18 Seconds

—————————————

Ki-61-II KAI Ko / Otsu:
Empty Weight: 2855kg
Loaded Weight: 3825kg
Wing Area: 20m2
Engine: Ha-140
Take Off: 1500hp (WEP)
1350hp at SL / 1250hp at 5700m
-
Max Speed: (Military Power / WEP)
Sea Level: 525kph / 544kph
3000m: 580kph / 601kph
5000m: 598kph / 620kph
6000m: 610kph / 612kph
10,000m: 544kph / 544kph
-
Rate of Climb: (Military Power / WEP)
Time to 5000m: 6:30 / 5:40
-
Stall Speed: (No Flaps, 1000m, 3825kg Weight)
166km/h IAS
-
Armament:
2x 12.7mm Ho-103
2x 20mm Ho-5
-
Sustained Turn Time: (WEP, Sea Level)
19 Seconds

——————————————

Ki-100-I Ko / Otsu:
Empty Weight: 2525kg
Loaded Weight: 3495kg
Wing Area: 20m2
Engine: Ha-112-II
Take Off: 1500hp (WEP)
1260hp at SL / 1350hp at 2000m / 1250hp at 6000m
-
Max Speed: (Military Power / WEP)
Sea Level: 485kph / 514kph
1000m: 510kph / 541kph
2000m: 538kph / 570kph
3000m: 542kph / 574kph
4000m: 545kph / 578kph
5000m: 567kph / 601kph
6000m: 580kph / 585kph
-
Rate of Climb: (Military Power)
Time to 1000m: 1:06
Time to 2000m: 2:10
Time to 3000m: 3:22
Time to 4000m: 4:42
Time to 5000m: 6:00 (5:00 WEP)
-
Stall Speed: (No Flaps, 1000m, 3495kg Weight)
158km/h IAS
-
Armament:
2x 12.7mm Ho-103
2x 20mm Ho-5
-
Turn Time:
17 Seconds

——————————————

Ki-100-II:
Empty Weight: 2700kg
Loaded Weight: 3670kg
Wing Area: 20m2
Engine: Ha-112-II Ru
Take Off: 1500hp (WEP)
1260hp at SL / 1325hp at 2000m
-
Max Speed: (Military Power / WEP)
Sea Level: 479kph / 508kph
1000m: 500kph / 531kph
2000m: 520kph / 553kph
3000m: 538kph / 572kph
4000m: 551kph / 584kph
5000m: 563kph / 594kph
6000m: 572kph / 603kph
7000m: 580kph / 610kph
8000m: 585kph / 614kph
9000m: 580kph / 595kph
10000m: 565kph / 571kph
-
Rate of Climb: (Military Power)
Time to 1000m: 1:16
Time to 2000m: 2:23
Time to 3000m: 3:51
Time to 4000m: 5:13
Time to 5000m: 6:40 (5:12 WEP)
Time to 8000m: 11:30
Time to 10000m: 18:00
-
Stall Speed: (No Flaps, 1000m, 3670kg Weight)
163km/h IAS
-
Armament:
2x 12.7mm Ho-103
2x 20mm Ho-5
-
Turn Time:
18.5 Seconds

 

[Ivan1GFP]

Hello Laurelix,
What are you using for Military Power and War Emergency Power for the Ha-40 and what altitudes are you getting your calculated speeds?

Your use of one set of weight specifications for the Ko/Otsu/Hei is a bit misleading because there were quite a few equipment changes between various models. Just for fuel load, the difference between one model to another could be as much as 250 liters.

There is actually quite a lot of information in the FAOTW series of books on these engines as well as the Ha-140 but there are quite a few details that are missing, especially with Emergency Power at altitude.

- Ivan.

 

[Laurelix]

Hello Laurelix,
What are you using for Military Power and War Emergency Power for the Ha-40 and what altitudes are you getting your calculated speeds?

Your use of one set of weight specifications for the Ko/Otsu/Hei is a bit misleading because there were quite a few equipment changes between various models. Just for fuel load, the difference between one model to another could be as much as 250 liters.

There is actually quite a lot of information in the FAOTW series of books on these engines as well as the Ha-140 but there are quite a few details that are missing, especially with Emergency Power at altitude.

- Ivan.

Ha-140
1500hp Take Off (WEP)
1350hp at sea level (Military Power)
1250hp at 5700m

This is what you'll find in the sources. This means that at 5700m, the WEP Power is 1390hp.

1500 / 1350 = 1.11111
1250 x 1.1111 = 1390

 

[Ivan1GFP]

Hello Laurelix,

That is NOT a valid technique.
You actually need to know something about the supercharger on the aircraft and any power adders such as Nitrous Oxide if you were dealing with German types, or whether it was a gated throttle as on some of the Merlin aircraft.

In most cases, War Emergency Power has a lower critical altitude because the WEP manifold pressure is higher and can't be maintained to quite the same altitude as Military Power because the Supercharger doesn't have the capacity.

I keep asking you about RPM because for most of these Japanese engines, there is a different RPM limit for Military Power and Emergency / Take-Off Power.

- Ivan.

 

[Shortround6]

Ha-140
1500hp Take Off (WEP)
1350hp at sea level (Military Power)
1250hp at 5700m

This is what you'll find in the sources. This means that at 5700m, the WEP Power is 1390hp.

1500 / 1350 = 1.11111
1250 x 1.1111 = 1390

It doesn't mean anything of the sort.

Military power at altitude was not some arbitrary limitation or percentage of a different power.
It was usually the limit of power the engine could make at a given rpm and supercharger set up.
Supercharger setup means step up gears, impeller, intake type and and so on. At altitude (not low level) the engine was turning it's max allowable rom and the supercharger impeller was turning it's max rpm and the throttle was wide open. That is the military power at 5700 meters. With no extra supercharger capacity there is no WEP at higher altitudes.
Supercharged airplane engines had to run with partially closed throttles at take-off/low altitude to keep from blowing the engine up. The higher the plane flew the more the throttle could be opened. Opening the throttle more than "normal" (Military power) gave the WEP at low altitudes with increased maintenance issues.

to show the problem with your "formula" consider the the Allison V-1710-73 engine used in the P-40K. 1325hp for take-off (51in MAP), 1550hp at sea level WEP (60 in MAP) and 1150hp military at 12,000ft (42in MAP).

It doesn't matter that the WEP at sea level is 1. 1698 times the take-off power. Or that the supercharger could actually deliver around 70in of manifold pressure at sea level. At 12,000ft the supercharger could only deliver 42in of pressure (with no ram) and 1150hp was all you were going to get unless you over revved the engine against Allison's, Curtiss's and the Army's recommendations.

I would also note that the Germans were only able to get 1355hp out of the DB605 at 5700 meters at 2800 rpm and 1.42 Ata. (1079mm ?) and the DB 605 was a 35.7 liter engine. the Ha 140 was how big? the Ha 40 was a 33.93 liter engine.

 

[Ivan1GFP]

I would also note that the Germans were only able to get 1355hp out of the DB605 at 5700 meters at 2800 rpm and 1.42 Ata. (1079mm ?) and the DB 605 was a 35.7 liter engine. the Ha 140 was how big? the Ha 40 was a 33.93 liter engine.

Hello Shortround6,

I believe we are mostly in agreement.
There are a couple minor points of difference.

With the German GM1 Nitrous Oxide system, it didn't quite follow the same rules because it was an oxidizer and essentially acted as a supercharger in a bottle. It WOULD work past the normal full throttle height.

1.42 ATA actually works out to about +285 mm Hg (Japanese) or 1045 mm Hg (Russian).
Ha-140 Bore was 150 mm, Stroke was 160 mm.

I had thought the DB 605 was a bit stronger than the numbers you are listing.
Power for Ha-140 is:
1500 HP @ 2750 RPM - Take-Off - +380 mm or 44.88 inches Hg.
1250 HP @ 2650 RPM - Maximum @ Sea Level - +380 mm Hg
1350 HP @ 2650 RPM - Maximum @ 5700 meters - +380 mm Hg
5700 meters is critical altitude. The source data listed "Maximum" which I interpret to be Military Power.

Now it isn't documented, but I wonder what would happen if the pilot decided to run the engine up to 2750 RPM at critical altitude. This isn't a consideration with US aircraft but most Japanese engines were running about 100 to 200 RPM less at their Military rating.

- Ivan.

 

[Laurelix]

Hello Laurelix,
What are you using for Military Power and War Emergency Power for the Ha-40 and what altitudes are you getting your calculated speeds?

Your use of one set of weight specifications for the Ko/Otsu/Hei is a bit misleading because there were quite a few equipment changes between various models. Just for fuel load, the difference between one model to another could be as much as 250 liters.

There is actually quite a lot of information in the FAOTW series of books on these engines as well as the Ha-140 but there are quite a few details that are missing, especially with Emergency Power at altitude.

- Ivan.

That's why Ki-61-II top speed is at 6000m at military but with WEP the top speed is at 5000m.
Also Ha-140 has 1250hp at 5700m at Military, not 1350.

 

[Shortround6]

With the German GM1 Nitrous Oxide system, it didn't quite follow the same rules because it was an oxidizer and essentially acted as a supercharger in a bottle. It WOULD work past the normal full throttle height.

You are correct about the effect of the GM1 but not all bf 109s were fitted with GM1 and certainly not all aircraft using DB 605 engines. I was trying to keep the comparison simple

Now it isn't documented, but I wonder what would happen if the pilot decided to run the engine up to 2750 RPM at critical altitude. This isn't a consideration with US aircraft but most Japanese engines were running about 100 to 200 RPM less at their Military rating.

It is indeed an interesting question. I would note that a number of early US engines used a higher rpm for take-off than they did for "military" power and/or some were not rated at "military" power at all (late 1930s to 1940-41?).

The F4F Wildcat with R-1830 engine being a special case in point as it was allowed to use 2700rpm for take-off but only 2550rpm for full power at altitude. Add in the fact that at least one manual says that 2800rpm could be used under special circumstances (extra short take-off?) for take-off.

However, for the US military power was a 5 minute rating while take-off power was often only a one minute rating. late in the war some US engines were allowed to use (officially) the military rating for 15 minutes.
Going back to the Germans, some of the DB601 engines were only allowed to use the highest boost rating for 1 minute and not 5 minutes and there was a clockwork timer that helped enforce the time limit. Engine automatically returned to the lower throttle setting at the end of one minute. I have no idea if there was delay in pushing the throttle forward again or how many times in quick succession the pilot could use that one minute burst of power.

An airplane also had to be set up to use such extra power as sometimes the prop was either too small to effectively transmit the extra power or was limited by the pitch range (the F4F for example didn't pick up much, if any speed by going past 2550rpm although it might have helped climb a little?)

 

[tomo pauk]

I would advise against using US terms for ww2 Japanese engines today. Yes, I know TAIC people used US terms back in 1945/46.
Without the 100 oct fuel or better, Japanese were using water/alcohol injection for emergency power, probably only on radial engines, and later in war. Ha-40 never got it, Ha-140 was such an unreliable engine that made BMW 801C/early D, Napier Sabre, Nakajima Homare or R-3350 look like bed of roses.

 

[Ivan1GFP]

That's why Ki-61-II top speed is at 6000m at military but with WEP the top speed is at 5000m.
Also Ha-140 has 1250hp at 5700m at Military, not 1350.

Hello Laurelix,
You are correct. re HP at 5700 meters.
I swapped the entries. It should be:
1350 HP Military @ SL
1250 HP Military @ 5700 meters.

.....
Going back to the Germans, some of the DB601 engines were only allowed to use the highest boost rating for 1 minute and not 5 minutes and there was a clockwork timer that helped enforce the time limit. Engine automatically returned to the lower throttle setting at the end of one minute. I have no idea if there was delay in pushing the throttle forward again or how many times in quick succession the pilot could use that one minute burst of power.

Hello Shortround6,
The Ha-40 was actually based on he DB 601Aa with the 1 minute Take-Off rating that you described.
It had a bit more power at low altitude than the DB 601A-1 but also had a lower critical altitude (I believe 3700 meters). The Germans only exported or licensed the Aa and not the A-1. The Japanese improved the supercharger enough to bring the critical altitude up to 4200 meters which still wasn't quite what the DB 601A-1 could do but was close. It would have been great for a fighter entering service in 1940 or 1941.....

An airplane also had to be set up to use such extra power as sometimes the prop was either too small to effectively transmit the extra power or was limited by the pitch range (the F4F for example didn't pick up much, if any speed by going past 2550rpm although it might have helped climb a little?)

I just ran some of the numbers for the Ki 61-I and -II to see how their propeller power coefficients compared with other fighters. I did the calculations using Military power output and with RPM for Military and Emergency settings.
The propeller setups appear to be very much middle of the range. They have "more propeller" than the Me 109G and P-40 series and a bit less propeller than the P-39 Airacobra but the numbers are not greatly different. This is using diameter rather than blade areas, but all are three blade propellers. There were other close values for aircraft with four blade propellers, but it is harder to make a comparison there without knowing a bit more.

I would advise against using US terms for ww2 Japanese engines today. Yes, I know TAIC people used US terms back in 1945/46.
Without the 100 oct fuel or better, Japanese were using water/alcohol injection for emergency power, probably only on radial engines, and later in war. Ha-40 never got it, Ha-140 was such an unreliable engine that made BMW 801C/early D, Napier Sabre, Nakajima Homare or R-3350 look like bed of roses.

Hello Tomo Pauk,
I believe you are correct about the terminology but one has to have some kind of standard for comparison.
With a fuel standard of only 91/92 octane, the Japanese were actually using Water-Methanol injection pretty much for anything over "Maximum Continuous" power. Normal Rate, Climb, Military, etc all relied on ADI.... for SOME engines.

Not sure why some engines needed it and some did not.
I think it MIGHT have had something to do with the boost pressures. The Ha-40 only ran at +240 mm and the Ha-140 ran at +380 mm while the Kasei and Homare were running +450 mm and +500 mm.

You are right that Ha-40 / Ha-140 never got it, but some models of the Sakae / Ha-25 / Ha-115 got it and some did not. For some reason, for the same engine series, the Japanese Army managed to get their Ha-115 engines working with ADI but the Navy never were successful with their Sakae 31 ADI. None of the Sakae ran at particularly high manifold pressures though.

- Ivan.

 

[Laurelix]

Added more Info, few corrections and made it more tidy and easy to read.

 

[mad_max]

You may find something you're missing or different than the data you used here. Paste link into new window.

drive.google.com/open?id=0B-ehXSd3MY6QdjFFSEI0S0plekE

 

[Laurelix]

• Stall Speeds and Turn Rates (At Sea Level) [Calculated]

=
Ki-61-I Ko (2950kg)
146km/h (Flaps Up)
123km/h (Landing Flaps)
Power to Weight: 2.86kg/hp (Military Power) - 2.54kg/hp (Combat Power)
Turn Rate: 16-17 Sec (Combat - Military Power)
=
Ki-61-I Otsu (3130kg)
150km/h (Flaps Up)
127km/h (Landing Flaps)
Power to Weight: 3.03kg/hp (Military Power) - 2.70kg/hp (Combat Power)
Turn Rate: 16.5-17.5 Sec (Combat - Military Power)
=
Ki-61-I Hei (3166kg)
151km/h (Flaps Up)
128km/h (Landing Flaps)
Power to Weight: 3.07kg/hp (Military Power) - 2.73kg/hp (Combat Power)
Turn Rate: 16.5-17.5 Sec (Combat - Military Power)
=
Ki-61-I Tei (3470kg)
158km/h (Flaps Up)
135km/h (Landing Flaps)
Power to Weight: 3.37kg/hp (Military Power) - 2.99kg/hp (Combat Power)
Turn Rate: 19-20 Sec (Combat - Military Power)
=
Ki-61-II KAI Ko (3825kg)
166km/h (Flaps Up)
143km/h (Landing Flaps)
Power to Weight: 2.83kg/hp (Military Power) - 2.55kg/hp (Combat Power)
Turn Rate: 19-20 sec (Combat - Military Power)
=
Ki-100-I Ko (3495kg)
159km/h (Flaps Up)
136km/h (Landing Flaps)
Power to Weight: 2.77kg/hp (Military Power) - 2.33kg/hp (Combat Power)
Turn Rate: 18-19 sec (Combat - Military Power)
=
Ki-100-II (3670kg)
163km/h (Flaps Up)
140km/h (Landing Flaps)
Power to Weight: 2.91kg/hp (Military Power) - 2.45kg/hp (Combat Power)
Turn Rate: 18.5-19.5 sec (Combat - Military Power)

Guess im more precise than Bunrindo which states 137-142km/h landing speed for Ki-100-I.
I used 1.44 CL_Max for Ki-61/Ki-100 Wing Lift Coefficient, That gave me 139km/h stall with landing flaps for the Ki-100-I

This is probably why i went with the 1.44 CL value

Furthermore the US intelligence says the Ki-61-I otsu could take off around 130kph

 

[Laurelix]

Armament and ammo count for the different Hien Fighters

• Ki-61-I Ko
Wings: 2x 7.7mm Type 89 (1000 rounds)
Nose: 2x 12.7mm Type 1 (500 rounds)
-
• Ki-61-I Otsu
Wings: 2x 12.7mm Type 1 (500 rounds)
Nose: 2x 12.7mm Type 1 (500 rounds)
-
• Ki-61-I Hei
Wings: 2x 20mm MG-151 (240 rounds)
Nose: 2x 12.7mm Type 1 (500 rounds)
-
• Ki-61-I Tei
Wings: 2x 12.7mm Type 1 (500 rounds)
Nose: 2x 20mm Ho-5 (240 rounds)
-
• Ki-61-II
Wings: 2x 12.7mm Type 1 (500 rounds)
Nose: 2x 20mm Ho-5 (500 rounds)
-
• Ki-61-II KAI Ko
Wings: 2x 12.7mm Type 1 (500 rounds)
Nose: 2x 20mm Ho-5 (500 rounds)
-
• Ki-61-II KAI Otsu
Wings: 2x 12.7mm Type 1 (500 rounds)
Nose: 2x 20mm Ho-5 (500 rounds)
-
• Ki-100-I Ko
Wings: 2x 12.7mm Type 1 (500 rounds)
Nose: 2x 20mm Ho-5 (500 rounds)
-
• Ki-100-I Otsu
Wings: 2x 12.7mm Type 1 (500 rounds)
Nose: 2x 20mm Ho-5 (500 rounds)
-
• Ki-100-II
Wings: 2x 12.7mm Type 1 (500 rounds)
Nose: 2x 20mm Ho-5 (500 rounds)

[Ki-61-II KAI Otsu, Colourized]

 

[Laurelix]

Added more detailed info regards to Ki-61-I Top Speed at different altitudes

 

[Laurelix]

According to several sources like this one

and this one

The Ki-61 / Ki-100 series were capable of up to 850km/h IAS in a dive and pilot testimonies indicate the airframe and the wings could withstand even more.

The designer Dr. Doi wrote in his Maru Mecha magazine

'The dive limit was set to 850km/h. In the load test, assuming a loaded weight of 2950kg, no damage occurred even if 15G's were applied to the main wing and the subsequent tests were stopped. Although the weight reduction of the main wing was considered to improve its performance, the Ki-61 was shelved because it had already shown sufficient performance. "" There has never been a case where the Type 3 fighter had undergone aerial disassembly. "

On one occasion a Ki-61 pilot with the late speedometer showing up to 1000km/h reached a speed where his speedometer reached its limit and was shaking, claiming he reached the speed of sound. On other occasions several Japanese pilots testified even reaching 900km/h and yet there was no wrinkle on the wing and no flutter occurred.

 

[Laurelix]

LMFAO
No wonder the Tony could achieve Mach 1, pull 15G's and it's wings would remain perfectly intact. It has 3 f****ing wing spars

 

[Laurelix]

Official Kawasaki document states '850km/h (Indicated)' as the official maximum safe dive limit for the Ki-61/100 series.
On the request of the person who shared the document with me, i cannot share it. But if you manage to get the document yourself, its right there.
Infact the secondary sources above most likely quote this same kawasaki document.

 

[Cripss_Sidmeyer]

The details about the Ki-61-I/Ki-61-II/Ki-100 structure:

 

[spicmart]

How could such a slender, delicate wing be so rugged? The weights of the Ki-61/100 in comparison with similar fighters do not indicate heavier structure.
How were three spars possible without being heavier?
I thought the Me 109 had a main spar with two auxiliary spars as well.