Japanese Piston Engines

[KevinB]

Shinpachi,

I'm very interested in the article but I am having difficulty with your link....my Web Browser shows it as "gibberish"....any tips would be appreciated.

Thanks,

[kool kitty89]

Here's a direct link: Translated version of http://www.warbirds.jp/kakuki/sanko/en_america.htm

[Shinpachi]

Sorry KevinB for my imperfect introduction of the engine lists but
here has come kool kitty89's good assistance!

That is what I want!
Thank you kool kitty89

[kool kitty89]

That's a good site, I found a very comprehensive one on US engines a while back (in English) with a similar layout of the data, but unfortunately I've lost it.

[red admiral]

This has a complete list of USAF engines and subtypes from the period with lots of details. It doesn't give WER power and some of the engines have been downrated in 1949 from wartime.

[kool kitty89]

Thanks, I liked the one I mentioned as a good quick refrence, kind of like this Junkers website The Hugo Junkers Homepage

[HoHun]

Hi Shinpachi,

>We regard the site itself as an edited data base because it covers not only Japan but U.S.A, Germany, Britain, France and Italy widely as if a volume of a book.

Ah, I see - thanks a lot! :-)

Have you ever seen Japanese WW2 aircraft or engine manuals that state the operating parameters of the powerplants?

Such manuals appear to be the best source for reliable data, but so far, I've only seen a translated Ki-44 manual once which mentioned boost pressures and engine speeds.

As there seems to be quite a bit of confusion regarding the operating parameters of the various A6M models, it would appear that the manuals would help us out of this difficult situation, so any hint you might have would be appreciated! :-)

Regards,

Henning (HoHun)

[kool kitty89]

I'm kind of interested in finding out more on the Japanese inline engines.

Not so much the Ha 40/140/240 (dirivatives of DB 601/605), but the lesser known V-12's (the Ha 2-2, Ha 4, Ha 9, Ha 21, and Ha 46), the Ha 9 being pretty much the only one to see significant use. (though the Ha 2-2 was, somewhat unsuccessfully, used on the Ki-1 bomber)

Particularly the origins of the designs. (what the're based on, coipis/license built, or dirvatives of other engines, or if they're indigenos designs)

[Shinpachi]

Hi HoHun.

I will translate descriptions about Sakae 21 from A6M3 Operation Manual.
Please give me a few days.

I fully understand your enthusiasm.
Thank you for asking me.

***********

Hi kool kitty89.

I'm also much impressed with your good knowledge about the Japanese engines. Please keep in touch with me as any information will be coming up

[kool kitty89]

Well before reading that site, all I really knew of (besides the DB based engines) was the Ha 9, I foun out about the Ki-1 after doing a quick search on the Ha 2-2.

Thanks for the info and any more to come.

[kool kitty89]

There's an english portion of that website too, WarBirds Is the database not accessible there?

[Shinpachi]

Hello kool kitty89.
There seem no secrets about Japanese web sites today.
You are checking them very well
I know the site but not checking so well.
Thanks for the info.

[Shinpachi]

Hi HoHun.
Here is my translation about the Sakae 21.

**************
Aircraft Engine

Name: Sakae 21

Number: 1

HP:
Nominal:
1,080 @1st stage of supercharger(on the ground)
1,100 @2nd stage of supercharger(alt. 2,850meters)
980 @2nd stage of supercharger(alt. 6,000meters)
Lift-off:
1,130


RPM:
Nominal: 2,700
Lift-off: 2,750

Manifold air pressure(Mercurial column in milimeter):
Nominal: +200*
Lift-off: +300

Nominal altitude(meter):
2,850 @1st stage of supercharger
6,000 @2nd stage of supercharger

Reduction Gear Ratio:
7/12 (0.5833)

Fuel:
Specific gravity: 0.72
Type: Aviation type92 volatile oil



Data Source: "A6M3 operation manual" at Japan Center for Asian Historical Records [Reference Code] A03032271200


*Note: Description about Manifold air pressure is indistinct.
It can be read "Nominal (0.25kg per square centimeter) +200 more or less with normal max(---) common for nominal 1st stage and 2nd stage" by Shinpachi's eyes.

Wishing any help for you

[HoHun]

Hi Shinpachi,

>Here is my translation about the Sakae 21.

Thanks a lot! That is great stuff, very useful in improving the accuracy of our knowledge of the A6M :-)

>1,080 @1st stage of supercharger(on the ground)
>1,100 @2nd stage of supercharger(alt. 2,850meters) <- actually 1st stage?
>980 @2nd stage of supercharger(alt. 6,000meters)

This is highly interesting - I had thought that the US TAIC engine data was based on guesswork (being war-time intelligence information), but their data was in fact identical to the Japanese rating you quoted. Here is the TAIC information:

Sakae model 21, TAIC 1944 p. 852
Take-off 1115 hp/2750 rpm/41.7" SL
WEP 1115 hp/2750 rpm/41.7" SL
WEP 1180 hp/2750 rpm/41.7" 7500*
WEP 1040 hp/2750 rpm/41.7" 18000*
MIL 995 hp/2700 rpm/37.8" SL
MIL 1085 hp/2700 rpm/37.8" 9350 ft
MIL 965 hp/2700 rpm/37.8" 19700 ft

Analysis:

TAIC and Japanese MIL rpm: match
TAIC and Japanese MIL boost: match (37.8" Hg = +200 mm Hg)
TAIC and Japanese MIL full throttle height: match
TAIC WEP and Japanese take-off rpm: match
TAIC WEP and Japanese take-off boost: match (41.7" Hg = +299 mm Hg)

At the first sight, the quoted powers do not seem to match, but it's important to remember that the international HP was 735.5 W while the Imperial HP was 745.7W, so the power figures match, too.

There is one value that is an exception, though:

>1,080 @1st stage of supercharger(on the ground)

This appears like a value that might be achieved at increased boost ... for +200 mm, 2700 rpm it seems to be too high as it almost matches the 1100 HP at 2850 m of the MIL rating, but mechanically-supercharged piston engines lose power as altitude decreases below full throttle height.

>*Note: Description about Manifold air pressure is indistinct.
It can be read "Nominal (0.25kg per square centimeter) +200 more or less with normal max(---) common for nominal 1st stage and 2nd stage" by Shinpachi's eyes.

Hm, this sounds like an important comment, but I don't entirely understand it ... could you explain it again, please?

Regards,

Henning (HoHun)

[Shinpachi]

Hi HoHun.

You are checking everything.
Much impressed.

1. >1,100 @2nd stage of supercharger(alt. 2,850meters) <- actually 1st stage?

Yes, it was my mistype. It had to be typed as you pointed out.

"1,100 @1st stage of supercharger(alt. 2,850meters) "


2. >*Note: Description about Manifold air pressure is indistinct.
It can be read "Nominal (0.25kg per square centimeter) +200 more or less with normal max(---) common for nominal 1st stage and 2nd stage" by Shinpachi's eyes.

When I read them very carefully, contents look very simple as follows.

"Manifold air pressure(Mercurial column milimeter)
Nominal 225* * normal max (1st stage)
+200 @ nominal 1st stage, 2nd stage
Lift-off +300 "

Here attached my work-table images for your references.

Wishing any help for you!