Looking for Ki 43 Hayabusa data

[Ivan1GFP]

The Ha-25 engine in the Ki-43-I appears to correspond to the Sakae 12 engine in the Mitsubishi A6M2 for power output
The Ha-115 engine in the Ki-43-II appears to correspond to the Sakae 21 engine in the Mitsubishi A6M3 for power output.

In looking at a diagram from the FAOTW 65, the reduction gear housing of the Ha-115 looks like that of the Ha-25 / Sakae 12 and is much shorter than that of the Sakae 21. From this I would assume that the reduction gear ratios of the Ha-115 and Sakae 21 are different.

Does anyone here know what the gear ratios are for the Ha-25 / Ha-115? Are they the same as the Sakae 12?

Thanks.
- Ivan.

 

[krieghund]

Here is two pages out of the TAIC manual on the NK1/Ha25 series engines

 

[Vincenzo]

here http://www.ww2aircraft.net/forum/engines/data-base-japanese-aircraft-engines-19466-2.html
Shinpachi posted data from japanese book

 

[Shinpachi]

Yes, Vincenzo. Nakajima's list says 0.6875(11/16) for the Ha-25 and 0.5833(7/12) for the Ha-115.

 

[Ivan1GFP]

Thanks Guys.

Seems like some of the data is contradictory though:
Compression is listed as either 7.0 or 7.2 for the same model engines depending on the source.
The NK1E (Sakae 31) shows a reduction gear ratio of .6875 while the NK1F (Sakae 21) shows .5833.

Any idea which values are correct?

Thanks.
- Ivan.

 

[krieghund]

Hard to say, I would like to think the TAIC guys performed a thorough job of data tabulation. Especially the guys who risked their lives behind the line to collect the data and specimens. I am not that familiar with the Intel philosophy of the day but I would like to think they had quality control methods in place to counter check on data especially the scribes putting it on paper. Then again my experience with the military would say that these were admin clerk positions in the back waters and the military has a way of putting people not suited for the job in these positions, kind of like trying to plow the field with a Cadillac. Of course motivation goes along way as well if the person in question is interested in this field of endeavor or if he is like a homosexual gynecologist not too interested in his job.

 

[Ivan1GFP]

Regarding the accuracy of the TAIC guys, For the Ki-61 Hien, there is a photograph of a long ruler or tape measure being stretched along the length of the airplane. There is another that shows the depth of the fuselage.

While the TAIC presumably would try to measure the aircraft as well as they could, It doesn't compare to the accuracy in dimensions that can come from the manufacturer. I build 3D models on the computer at times and would want the most accurate dimensions possible. Often they do not know what the specified loads would be for a captured aircraft and might overload or underload. Another issue would be guessing at the throttle settings if there isn't a manual.

BTW, What would be the "Basic Weight" of the the Ki-43?

- Ivan.

 

[krieghund]

Well the best I can figure consulting all my pubs I figure these are the empty equipped weight (less pilot, fuel, oil and ammo)

Ki43 IIb = 4050 lbs

Ki-43 IIIa = 4094 lbs

Ki-43 IIIb = 4244 lbs

Remember when calculating the loaded weights the Model III has a 90 to 100 liter methanol water tank behind the pilot.

 

[Ivan1GFP]

Thanks Krieghund,

Here is a quick check for the Ki-43-IIb: (with a few assumptions)


Empty Equipped ------------------- 4050 pounds
Pilot (75 kg) -------------------- 165.3 pounds
Oil (45 Liters) ------------------ 88.3 pounds
Fuel 300 Liters (Tank #1) -------- 475.5 pounds
Fuel 263 Liters (Tank #2) -------- 416.8 pounds
Ammunition 12.7mm x 1000 rds ----- 113.4 pounds

Gross Weight --------------------- 5309.4 pounds


Specifications call for 5320 pounds but since we have not included minor equipment such as Flare guns, etc. This seems quite reasonable.

Assumptions are the following:
Fuel Tank sizes are those of a Ki-43-I and I believe the Ki-43-II carried a few liters less.
Ammunition weight is for the Italian 12.7 mm MG which uses identically dimensioned ammunition though the round weights may be different.

Is there anything obvious I left out?

- Ivan.

 

[krieghund]

I believe the best explanation of the fuel quantity discrepancies between the Model I and II results from the type of tank protection applied. This even causes the same model to have variances.

The Ho103 12.7 MG ammunition weight was 4.06 oz per round. I don't have the link weight to hand but I will look for it. Also the Ki-43 II carries 250 rpg which puts the weight of ammo around 125 to 130 lbs. Other than than that I think you are pretty close considering there are so many variances in the data published. One way to get a higher degree of accuracy is find a Museum that has one and see if it was weighed and the equipment fit when weighed.

Just a thought, as I did that for the A6M3 Model 22 that was flyable a while back and got the weight and balance sheet for it.

 

[Ivan1GFP]

Hello Krieghund,

Thanks again for the data.

I do have some estimated data for the Ho-5 20 mm, but that was for the Ki-43-III. (8.4 ounces per round + link, 7.654 ounces for the round without the link.)
For the Ho-103 12.7 mm, I know the dimensions of the round are the same as the Italian 12.7 which was apparently based on the old Vickers gun. The Japanese gun has a good bit more muzzle velocity and also uses an explosive round, so I can see there being a weight difference. What is the data source for the 4.06 ounce per round weight?

The rear wing tanks (1) don't seem to vary between different models of the Oscar, but the front tanks (2) do. What I have for the Ki-43-II is 528 liters versus 563 liters for the Ki-43-I. My wife confirmed that my guess as to the 45 liter listing was engine oil. My assumption for oil density which varies a LOT with temperature was for 20 degrees centigrade.

My biggest lack of data at this point is ammunition weights for Russian Aircraft Guns such as their 12.7 x 108 and 20 mm x 99R.

The problem with a weight and balance sheet for the A6M3 Model 22 is that the modern aircraft are flying with a P&W R-1830 instead of a Nakajima Sakae. There are going to be differences between modern and original radios which are not insignificant and I suspect the modern plane doesn't carry guns.

Thanks.
- Ivan.

 

[krieghund]

Ok your question on the 12.7mm round weight had me hit the books...I had a penciled annotation in my TAIC working copy but I hadn't put a source with it. Well I'm here to tell you I can give you everything to know about the ammo for that weapon except the round weight which was hardly ever mentioned even in EOD pamphlets. However I prevailed. The weight of the HEI round is almost identical to the Breda round upon which it is based but just a hair heavier at 2.98 oz per round and with a link comes to 3.69 oz. So 500 rounds comes to 115.19 lbs.

I will see what I have on Russian Ammo.

The weight and balance sheet I have somewhere is for a Sakae equipped aircraft.

 

[Ivan1GFP]

Hello Again Krieghund,

I have a perhaps silly question for you: Who has a flyable A6M3 Model 22 that is flyable today with a Sakae engine?
I thought the only flyable Type Zero fighter with a Sakae that remains operational is the A6M5.

Any data forthcoming on the Soviet guns?

Thanks.
- Ivan.

 

[krieghund]

Sorry I spoke before finding the W&B sheet. The aircraft has a R-1830 engine in it and appears to been modified in Russia and was originally a A6M2 Model 21. However the aircraft has four wing tanks and one fuseage tank. The fuel quantity listed on the W&B sheet does not equal what the 'real' A6M3-22 carried. It carried 152 US Gals and clean take-off weight of 5906 lbs.

 

[Hiromachi]

XI. Turning Performance:

Altitude/Direction/IAS/Radius/Time/RPM/AMP
1969'/Left/205 m.p.h./307.4'/10.8/2700/37.8
1969'/Right/205 m.p.h./301.5'/11.0/2700/37.8

Note: Turns are executed without difficulty but the ailerons get heavy with increased speed.

Please forgive me for digging this thread, but I spotted this data and thought of using them.
But before I made some basic counting's (I'm only law student, don't have much knowledge in aviation). However, if we make basic math - length of circle with 93.7 m (307.4) radius = 588.73, speed in a turn is 330 km/h (205 mph) which equals 91.6 m/s. We divide 588.73 by 91.6 and we get 6.42 seconds. So this all looks very unlikely to be real, I mean if this is sustained turn ... Turn radius most likely would be around 500 feet.

10.8 sec would give 5.7 G, so that doesn't look to be executed without difficulty.

I hope someone can prove me wrong, otherwise that data doesn't seem real for sustained turn, maybe it is instantaneous ? Or maybe I just made some mistake...

 

[J311yfish]

This looks to be a Ki-43 performing a 180-degree turn in about 6 seconds:

View: https://www.youtube.com/watch?v=1BXo-jWcGnw

 

[GregP]

Something is fishy here. The formula for the radius of a level turn is: R = V^2 / (g * tangent[bank angle]), and you can get the bank angle from the arc cosine of (1/ g-force).

At 205 mph and 2.92 g, you complete a 180° turn in 10.7 seconds with a radius of 1,024 feet at 17° per second turn rate.

AT 205 mph and 5.7 g, you could complete the 180° turn in 5.2 seconds with a radius of 501 feet at 34° per second turn rate ... IF you had the power and an airfoil that could DO it. I cannot think of ANY WWII plane that can turn at 34° per second, so that sounds pretty much like pie in the sky to me. I am quite suspicious of values above around 20° - 25° per second even for a maneuverable Japanese type and I don't believe any WWII fighters could sustain much more than 4 g's in a level 180° turn ... not that the wing couldn't do it, but they didn't have the excess power to stay level at more than around 4 g's. Might be wrong in this, but would be glad to discuss it.

I work in SAE units (mph and feet), but working in metric units is no trouble if it helps the discussion.

 

[nicknack]

Hi Everyone

I stumbled across this website when looking for detail information on the ki43 and zero.

Wonder if anyone has any drawings of the cowl/nose sections for the ki43 IIb or III, I would be very thankful for any such information or drawings.

Also does anyone have a source or even be kind enough to provide some drawings for the Mitsubishi A6M5 cowl?

My interest in this is mostly a mix of large scale plastic models and scratch built Remote Control Aircrafts with a bit of 3D modeling to help out.

thanks
Nick

 

[Shinpachi]

Wonder if anyone has any drawings of the cowl/nose sections for the ki43 IIb or III, I would be very thankful for any such information or drawings.

Also does anyone have a source or even be kind enough to provide some drawings for the Mitsubishi A6M5 cowl?

Hello Nick.
Welcome to the forum and Thank you for your PM.

As long as I know, no detailed cowl drawings for the models you are searching for are available.
I have ever seen such one for A6M3 only before.
Best way will be to cut and trace the overall 3-views like from the followings.

Ki43ii
Ki43iii
a6mzero

Good luck!

 

[Hiromachi]

Something is fishy here. The formula for the radius of a level turn is: R = V^2 / (g * tangent[bank angle]), and you can get the bank angle from the arc cosine of (1/ g-force).

At 205 mph and 2.92 g, you complete a 180° turn in 10.7 seconds with a radius of 1,024 feet at 17° per second turn rate.

AT 205 mph and 5.7 g, you could complete the 180° turn in 5.2 seconds with a radius of 501 feet at 34° per second turn rate ... IF you had the power and an airfoil that could DO it. I cannot think of ANY WWII plane that can turn at 34° per second, so that sounds pretty much like pie in the sky to me. I am quite suspicious of values above around 20° - 25° per second even for a maneuverable Japanese type and I don't believe any WWII fighters could sustain much more than 4 g's in a level 180° turn ... not that the wing couldn't do it, but they didn't have the excess power to stay level at more than around 4 g's. Might be wrong in this, but would be glad to discuss it.

I work in SAE units (mph and feet), but working in metric units is no trouble if it helps the discussion.

Hmpf, sorry for late answer but was busy. I figured that Japanese didnt measure sustained turn, at least none of the manuals I've crossed ever appeared to prove otherwise. Even tests on N1K1 Kyofu Fowler Flaps were provided only with single turns.
I guess in single turn it looks different than in sustained.

This gentleman could tell us something but I got no clue how to contact him, maybe Shinpachi could find something. The website seems to be under construction still and lacks many data and links :
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