Ki-100 peformance

[alejandro_]

I found these data in j-aircraft:

【V-Max（km/h / m）】
500 / 1000
520 / 2000
539 / 3000
543 / 3210
536 / 4000
551 / 5000
575 / 6000
578 / 6140
568 / 7000
556 / 8000
542 / 9000
527 / 10000

【Climb to（m / minutes】
1000 / 1'12"
2000 / 2'13"
3000 / 3'08"
4000 / 4'29"
5000 / 6'00"
6000 / 7'25"
7000 / 8'56"
8000 / 10'57"
10000 / 20'00"

Posted by Hiroyuki Takeuchi. No details on aircraft condition, fuel or power used. I have compared the performance to other estimations and a Ki-61 test.

 

[krieghund]

Here is some more info..........How's your Japanese?

 

[tomo pauk]

Hi, alejandro,

The green line at your graph goes as far as 700 km/h (Ki-61-II). Any good data about that?

 

[alejandro_]

Hello Krieghund Tomo Pauk

Thanks for the information, my japanese is a bit rusty. . Do you have the book's title (or document) for the second page you uploaded.

Tomo Pauk, the data you refer to comes from a TAIC manual. I do not have any evidence of Ki-61-II being tested in the US, thus I assume its an estimation based on the Ki-61-I performance and II extra power. However, in my opinion is very optimistic. Ki-61-II was plagued by engine power, and Ki-61-I did give loads of trouble as well. As a matter of fact, the ones tested by the US Navy was probably the best maintained sample in the whole pacific (better fuel, great attention to setup and use of as many spare parts as possible as it was the only sample available).

http://www.ww2aircraft.net/forum/aircraft-requests/ki-61-tony-speed-altitude-diagram-27545.html

 

[krieghund]

Yes here is the cover, I think the engines manufactured by Aichi were better built than by Kawasaki. The M6A1 Seiran's AE1T Atsuta 32 could produce 1700 HP, quite a feat for a DB601 class engine.

 

[tomo pauk]

The Japanese themselves state max speed at 610 kmh (in table provided by krieghund) for the -II (Ha-140 engine, under 1500 HP). As for the US table's from the link you gave, it contains a disclaimer that figures written there are not from the tests, but from 'fragmentary documentation extrapolation from engine specs'.
Anyway, if we take a look what German, Italian British planes were doing with similar power drag (ie. 380-400 mph for Spit V, 109G-6, Italian 5 series), the US table about Tony II looks definitely wrong.

 

[Ivan1GFP]

The Japanese had a tendency to state their maximum speeds under "Military Power" as versus the US approach of stating performance under "War Emergency Power". Sometimes the often quoted performance number is not what we expect. The most glaring example of this is the max speed of a J2M3 Raiden which is often quoted at 371 mph. This number is accurate but it was while carrying a drop tank. Without the drop tank, the tested aeroplane achieved 407 mph which is quite credible in my opinion.

The Ki-61 in either version was quite a sleek looking design. With similar installed power to the Me 109E, the Ki-61-I achieved about the same speed. It seems to me that with very similar installed power to the Me 109G, it should achieve similar speeds as well. The 109G was about a 400 mph aircraft plus or minus a couple MPH. The typically quoted 387 mph was of a Me 109G-6/R-6 which carried a cannon pod under each wing.

- Ivan.

 

[Shortround6]

The Japanese had a tendency to state their maximum speeds under "Military Power" as versus the US approach of stating performance under "War Emergency Power".

- Ivan.

The problem here is that not all engines had a "War Emergency Power" rating. And many of the ones that did have a "WER", the rating was at a lower altitude were the the air was enough thicker that the "top" speed of the aircraft did not change. If "top" speed was achieved at 20,000ft with Military power XXX then WER at 14,000ft of XXX + 15% does nothing for the speed at 20,000ft and above although it will improve speed at sea level to 14,000ft and above tapering off the higher you go. WIth the air that much thicker at 14,000ft the plane may go faster at WER than at MIL power at that altitude but it still may not be faster than the plane goes at 20,000ft.

WER usually depended on excess supercharger capacity at the lower altitudes, fuel or water/alcohol that would allow higher than "normal" boost without detonating, and a cooling system that will handle the extra heat for X number of minutes. Plus the engine had to be strong enough to stand the power without breaking.
US engines like the R-1820, R-1830, R-2600 never (or rarely) got WER ratings and the R-2800 only got it with water/alcohol.

Different countries may have had different definitions of "Military" power however.

 

[Ivan1GFP]

Perhaps we should use different terms then:

How about Max continuous, 30 minute, 5 minute and 1 minute ratings? Except for the 1 minute (typically a "Take-Off" power) rating, just about everyone had a rating that corresponded to these though the terminology might be different. 30 minute might be the same as "Climb" power.

Consider the discussion over at J-aircraft about the max speed of the A6M2 Model 21 Zero. Their stated max speed is 316 mph at military power. US Testing of Koga's A6M2 arrived at 332 mph in an aircraft that admittedly was not in perfect shape.
I know they have some issues with translating the Japanese throttle settings to corresponding US settings in that discussion.

- Ivan.

 

[razor1uk]

US speed figures afiaa, were nearly always for clean aircraft at WEP or near limit of relialbe higher power settings; for fighters, where as the aerial military arms of Japan, more often used the more normally loaded configuaration without WEP for theirs, giving a better idea of actual operational performance; easier to work out ranges and flight times over long distances for missions.
For camparison sake, those whom prefer US aircraft, maybe should ignore their own non-operationally loaded figures with WEP.

 

[Shortround6]

Things changed with time.
US didn't adopt WER settings until late 1942 or early 1943. ALL early performance figures were done at either Military power (5min or 15 min) or "normal" (max continuous) power which either had a ONE hour or no time limit. Time to altitude figures were often done with the first 5 minutes of the climb at Mil Power and the remainder of the climb at "Normal" power.
Then there is a transition period in which max speed may or may not be quoted with "WER" depending on the plane and then you have the late war war period were almost all if not all fighters had a WER rating.

Again with the Japanese, you have to know if there was a WER rating or not. Some Sakae engines had a water/alcohol system, the early ones did not. When engaged on the later engines that would be the equivalent of WER. If the engine was not fitted with with the system there is NO WER.

"A6M2 Model 21 Zero. Their stated max speed is 316 mph at military power." It may not be the same as "U.S." military power, it may be max continuous power.

U.S. Military power was often the same rpm and manifold pressure as take-off power. While it had a time limit it could be used as often as required subject to the time limit and REQUIRED no extra notes in log book or maintenance inspections/procedures, UNLIKE WER use. EACH use of WER had to logged and depending on the engine (and time period) inspections or maintenance procedures were modified to take into account the use of the WER. Use of WER could trigger more frequent spark plug changes (sometimes after every use) and drastically shorten the life of the engine before it was pulled for routine overhaul, at least until more experience was gained.
Without knowing what the Japanese (or other countries) procedures were it is difficult to say if their WER settings were equivalent to the American ones.

 

[Ivan1GFP]

Untitled Document

This article gives a bit of insight about the Sakae 21 engine as installed in the A6M2 Model 21 Type 0.
I believe most of this article is credible though the translations of throttle settings are a bit off.

The statement here is that Koga's Zero was tested at 35 inches MAP (+150 mm). My calculations put +150 mm at 35.8 inch MAP.

The article also comments that there was an "Overboost" setting at 38 inches or +250 mm. My calculations put 37.8 inches at +200 mm. To me, this seems like the equivalent of our War Emergency Power.

As you pointed out, there was no Water / Alcohol injection system for the Sakae 21, but I don't see how that precludes it from having a War Emergency setting.

- Ivan.

 

[Shortround6]

The author of the article seems to be confusing or blurring "military or 30 minute rated power" as they are not the same thing. and "not over boost (roughly "war emergency power" in U.S. terminology)" is also a bit confusing.

For an example see: http://www.zenoswarbirdvideos.com/Images/P-39/P39SEFC.pdf

The 1000hp at 2600rpm and 39.2 in is the "Normal" or 30 min rating (actually US engines did not usually have a 30 min rating, it was often either 60 minutes or until the fuel ran out=max continuous)
For this engine the next step is "military power" 1150hp at 3000rpm and 44.5inches. In this case it has a 15 min rating but many US engines had a 5 min rating at MIL power.
Next step is the "take-off" rating, in many cases it was the same as "Military power" and is usually 5 min. The use of MIL or T-O power triggered NO EXTRA maintenance procedures and instances of use were NOT logged in the aircraft's records. In this case it was allowed to use 1200hp and 50.5in of boost which is certainly "over boost" compared to Military power.
The WER rating is 1420hp using 57in of manifold pressure.

As an example of how terminology changed see: http://www.zenoswarbirdvideos.com/Images/B-25/B25SEFC.pdf

Please note there is no "military" or WER on the chart. But the "Maximum Emergency" rpm and manifold pressure and power output are those of later R-2600 engines that have "Military" ratings. Again, please note the time limits and please note that "take-off power" required more "boost" than MAX emergency power, by roughly 50-75mm.

This is just different terminology by the US Army depending on the date in the war. Trying to compare to other countries rating systems or procedures can get really difficult. The British used the 30 minute rating and I believe the Germans did too. I don't know if an engine that can go for 30 minutes at power level XXX can go longer or if it introduces wear problems. ALL these power levels were subject to temperature limits. exceeding oil, coolant, or cylinder temperature would call for throttling back regardless of the time limit.
Many engines were Throttled to less than full power for take-off in normal conditions. Being able to "overboost" in difficult conditions for a few moments or even several minutes is not quite the same thing as a WER setting.

I do not disagree with the fact that the tests of the Zero with less than full rpm and boost do not reflect it's true performance but I do have strong reservations about the "terminology" used.

As in this sentence. "Sakai distinguished between normal full power speed (316 m.p.h.) and over boost (345 m.p.h.)."

In US use "normal full power" can mean the MAX continuous rating, which in the late 1930s was considered the engines "normal" rating.

You are NOT going to pick up roughly 10% in speed by increasing the manifold pressure by 8.5%. For instance if our plane needs 1000hp to do 345mph it will only need 742hp to do 316mph.

Another problem with this article is that it fails to take altitude into account. The Sakae 21 engine used a two speed supercharger instead of the single speed of the Sakae 12.

Zeros with Sakae 21s were deployed into combat areas in the Spring of 1942 which makes depending on combat reports to confirm the speed of the Zero 21 a bit of a problem. How did the F4F or P-39 pilot KNOW which engine was in the Zero he was chasing or was chasing him?

 

[Ivan1GFP]

Oops. My Goof.
I meant to write Sakae 12 because that was the engine installed in the A6M2 Model 21 that is described here. Single speed supercharger.

Surprisingly the A6M3 Model 32 and Model 22 which used the Sakae 21 did not appear to offer any significant speed increase. In fact in US Tests, the A6M5 wasn't significantly faster either (335 mph) even though what is typically listed for the type is 351 mph. There are lots of data points for various models of this aircraft and many of them don't fit together very well.

I know I am going a bit off topic, but the only point I was trying to make here was that there WAS a WEP setting in the earlier Sakae engines before the Water / Methanol injection in the Sakae 31.

- Ivan.

 

[GregP]

My reference for the performance of Japanese aircaft comes from the book, "General View of Japanese Military Aircraft in the Pacific War," by Nippon, Gunyokio No Zenbo. I have both the Japanese text and the English text. The Japanese text was first published in 1953. The English text was first published in 1956.

It gives to takeoff rating of the engine, but no indication of WER or of power at the max speed/ altitude combination or at what opwpoer was used to attain the speed. However, max speed is USUALLY attained at the maximum height at which the power system can maintain maximum power. The "WER"rating should not be used because it was NEVER intended as normal operation ... but many Allied performance tests did use the WER rating.

The A6M5 Model 52 is quote as 565 kph at 6,000 meters, which is 351 mph at 19,685 feet.

This text was compiled by the saff of Aireview" by Kantosha, Tokyo, Japan and is a treasure of information, especially if you read Japanese! I don't but have friends who do.

 

[Gaston]

duplicate

 

[Gaston]

Whatever the straight line performance was (a low 595 km/h at WEP is quoted for the Ki-61-I, so 650 km/h at WEP for the Ki-100 seems high but could be close to correct. The same 650 is quoted for the J2M3 and again the same is also quoted for the similar 1500 hp power Ki-44 in one Tokyo area defense evaluation (the same where the ki-61-I is only listed as 595), and 695-710 km/h is well established for the Ki-84), it is worth noting the Japanese extensively tested the Ki-100 as so superior to the Ki-84 that one of them could take on three Ki-84s and have a resonable chance of winning from co-alt, then do the same after switching pilots... That's how huge the margin of superiority of the Ki-100 was, despite 30 mph inferior speed. The Ki-84 dived better, but that was the only other advantage it had.

Gaston

 

[Ivan1GFP]

I had not been following this thread for a while, but here goes....
I will admit up front that this is more or less an informal summary of what I have read from various places. I will try to find specific references if it comes to that.

The Ki-61-I is very close to a Me 109E in speed and climb. It has about the same engine power and drag but does it with a substantially larger wing 215 ft^2 versus 175 ft^2. It doesn't have slats so that might make up for some of the wing area differences.

The Ki-61-II is very close to a Me 109G in speed IFF its engine is working to advertised performance which makes it about a 400 mph fighter. In general, the Japanese engines were not able to achieve the same supercharger performance that their German originals did, so perhaps the speed at altitude was a touch less. There were VERY few of these planes and the engines generally were not reliable.

The Ki-100 had about the same power as the Ki-61-II but was much lighter in weight. The engine installation had a lot more drag so speed was only a bit more than the Ki-61-I.

The J2M Raiden was a different beast entirely. With about 1800 HP and a tiny laminar flow wing, it was a whole lot faster. US Tests put this critter at 410-415 mph clean and 371 mph with a drop tank. Handling was quite good by US standards though poor by comparision to Japanese types such as the A6M or Ki-43. Wing loading was high by Japanese standards, but wasn't by international standards. The engine was quite reliable and build quality according to US technicians that examined them at Yokosuka was quite good.

Sometimes speed isn't the only factor to be considered. Handling and Climb can also be quite important. Consider that the Spitfire Mk.IX is about 30 mph slower than the P-51D but is better in performance just about everywhere else.

- Ivan.

 

[Gaston]

TAIC tests I read put the J2M3 closer to 405 mph, which is a lot slower than a fairly well accepted figure now for the Ki-84 at around 430-435 mph... I would be interested to know where your J2M figures came from, as they do seem plausible given the power and weight.

J2M3 was maneuverable enough to be known to occasionally force catastrophic structural damage on US P-51Ds in some high-speed dogfights...

Ki-100 was indeed lighter than the Ki-61-II by about 700 lbs, but was still heavier than the Ki-61-I by 100 lbs...

It is indeed remarkable that while being 30 mph slower than the P-51D, the Spitfire Mk IX at +25 lbs was probably the best climbing piston-engined single engine fighter of WWII to be used in any large numbers... I don't know how much tighter it turned though: The margin was probably not that huge in slow-speed turning, and the P-51D could definitely out-turn the Spitfire for 180° (thus only briefly) above 300 mph (tighter radius): British RAE tests: P-51D: 450 yards radius. Spitfire Mk XIV: 625 yards radius. Both tests at 400 mph.

It is remarkable to note in combat how little, especially in the Marks after the Mark V, the Spitfire is used in turning combat, and is almost always used in diving and zooming maneuvers.

Gaston

 

[Jabberwocky]

British RAE tests: P-51D: 450 yards radius. Spitfire Mk XIV: 625 yards radius. Both tests at 400 mph.

It is remarkable to note in combat how little, especially in the Marks after the Mark V, the Spitfire is used in turning combat, and is almost always used in diving and zooming maneuvers.

Gaston

More horse pucky

RAE test please. I'll take a link, the title of the test or even a secondary source that contains a reference to the test.

Extraordinary claims require extra ordinary proof. I've asked you for this evidence on several different websites over the course of several years, and you've yet to even acknowledge my request...

Just to show everyone else how full of it you are:

Aces High BB post from 2009:

Gaston:
Apparently the P-51D at 400 MPH could make a 180° turn of 450 yards radius, wich handily beats even the Spitfire Mk XIV, quoted at 650 yards radius at this same speed. (Some may recall I had quoted this wrong in feets...)

So, is it a 180° turn or a 360° turn?

And, from the Ubi forums, same year, same outrageous statement and a fair bit of weasling when asked for evidence:

Gaston:
The Spitfire 14's quote of a turn radius of 625 yds, vs 450 yds for the Mustang, at 400 MPH, is from Skychimp, who was the discoverer of the NACA 868 report, whose fig. 47 we all have been posting for about ten years now...

Only now its 625 yards.

Got that data right have we? Are you sure.

Again, in 2010

Gaston:

Minimum radius of turn for the Spitfire XIV at 10 000 ft. going at 400 MPH (Farnborough test): 625 yds...

P-51D (with metal elevators likely!): 450 yds...

So, now we have an exact altitude. Still no evidence though...