Ki-84.........420 MPH???

[Karnak]

-ammo-,

The suggestion here would be to use the Ki-84-II data given that the only real difference was the wooden parts.

[Vermillion]

While I love the Ki-84, a FM built on the 420mph data would make it an "uber plane".

Basically imagine an aircraft as manueverable as the N1K2-J, and that is faster than the P-51D from about 18k down to the deck.

Why would anyone fly anything else?

When the Ki-84 in question was tested head to head with a P-51D and a P-47D, it outperformed each aircraft in every way until you got above 20k.

Hell, I'd be happy to just find a detailed report on the aircraft and the testing that occurred.  Its like a will-O-wisp trying to find that old data, and it was a hobby of mine for a couple of years.

[BUG_EAF322]

Why do u guys want everybody to fly the ki-84
Because that's what im gonna do when a 420mph uberturnclimbanddive plane is gonna be released in AH

since the 414 mph p38 is gonna be totaly worthless against it.

Yes i want that plane that is gonna get everything out of balance.

WTG go get it!!!!`

[mora]

Originally posted by brady
This guy I quoted above, says that the higher octane fuel would not of increased the Ki-84 preformance, since it was designed to operate on lower (well 87) Octane fuel. He also says that the test was run using 87 octaine fuel for the Ki-84. I will link the thread hear so you can read it in detail it is very interesting and their are more figures and referances:

A quote from the thread linked below:

"Just for reference about aviation gas, during WWII the US used 3 grades and they were classified as 80/87, 100/130, and 115/145. I'm also pretty sure that high performance American fighters only used the 115/145 grade. Also my 1972 Sanderson 'Private Pilot Manual' says it is ok to use a higher grade of the gasoline than your engine is rated for if your grade isn't available for a short period of time but it will not improve performance. "

See this thread all te good stuff is buried in the middle of it:

http://www.matrixgames.com/default.asp?URL=http%3A//www.matrixgames.com/forums/

You can use higher boost pressure without knocking when using higher octane fuel, and that improves performance. 1972 Sanderson is correct when it comes to normally aspirated engines.

[brady]

"You can use higher boost pressure without knocking when using higher octane fuel, and that improves performance. 1972 Sanderson is correct when it comes to normally aspirated engines."

 So your saying that since the Ki-84 was not normaly aspirated that the suposidely higher octane fuel burned in it during the test provided a better preformance?
  The guy also mentions that they DiD Not use 100 octane fuel, as normaly beleaved in the test with the Ki-84 post war but the 80/87 octaine fuel.

[butch2k]

[Pyro]

I have (hopefully, that's not a "had" because I can't find it) a translated Ki-84 manual.  IIRC, the performance listed in there was quite a bit less than the TAIC estimates.

[brady]

Frankely I was a bit shocked at the preformance figures this Lemurs fellow was sugecting, howeaver he presented a good case for his sugestion of 415-420 mph for the Ki-84, so I enquired hear to see just what everyone thought. I have E mailed him and provided a link to see if we can get him to come hear a debate the issue.

[butch2k]

Pyro i suppose they are more on par with the first two columns shown below

[mora]

Originally posted by brady
"You can use higher boost pressure without knocking when using higher octane fuel, and that improves performance. 1972 Sanderson is correct when it comes to normally aspirated engines."

 So your saying that since the Ki-84 was not normaly aspirated that the suposidely higher octane fuel burned in it during the test provided a better preformance?
  The guy also mentions that they DiD Not use 100 octane fuel, as normaly beleaved in the test with the Ki-84 post war but the 80/87 octaine fuel.

I'm not saying anything about that particular KI-84, but I just noted that with a little or no adjustments you can get higher power from a super/turbocharged engine with higher octane fuel.

[SmokinSS]

I am not an aircraft mechanic so take this with a grain of slat please.  I do however build high performance engines on a side job.

Whenever you have an engine that is super/ turbo charged, nitroused or with a very high compression ratio ( normally above 10.5/1) a higher octane fuel is required to help prevent detonation inside the combustion chamber. A higher octane fuel is not easier to burn and requires more heat to start the flame front inside the cylinder. A colder spark plug and a closer gap helps in this aspect also.

I don't know how this is affected with altitudes higher than what you would find at a race track. We do carry a small weather center with us when we go to read air density, temp and humidity so we can have an idea of how to tune the car that day.

I don't know if this will help or even contribute to the conversation just throwing the ole .02 in.

Have a great weekend.
Robert

[Michael Johnson]

Hi all,

Brady, i am Lemurs from Matrix.

Quote:
The test was performed with 100 octane fuel. In a war condition (no ammo, but with guns) aircraft that was reconditioned here in the US.

I have several magazine articles from the 70's that talk about this in depth. However, there is no known records from the flight tests, and I've checked with the Air Force Musuem on the issue.
End.

Actually, I did not know what fuel was used.  Thanks for the info on the test... the data at NARA seems to have been lost as i could not find it!

Like i said at Matrix this is just a logic chain that i am working on.
I have a feeling that 'bad quality & control' on late war Japanese engines is more complicated than we know.

I have found some data on Jap engines since i origionally posted and it seems the HA45 was built for 93-94 octane fuel.  100 octane fuel would probably boost you by 2-3mph. Thats it.
Higher octane fuel does not burn as easy so with a lower compression engine you will eventually have a dirty intake and it won't help your performance much. Anything higher than 100 octane would not help at all and would degrade your performance quicker.
HOWEVER, by '44 Japan was using pine nuts, coal, shale, etc to make aviation fuel and i have heard that much of the late war fuel was in the range of 85-87 octane which is just not enough.
That is why Jap pilots at the end of the war reported performance gains using allied fuel.
And i suspect much of the 'bad engines from the factory' was low octane fuel prematurely detonating.

I realize Japan had many troubles building things to spec at the end of the war, this was a project to see what the Ki-84 was capable of as built in Japan when the engine worked.

Michael

[Mitsu]

Ring Ring!!....It's time to bring Ki-84?

[Michael Johnson]

Hi all,

As i said in my post on Matrix this is all putting together pieces for me.

One of you said you had a translated flight manual for the Ki-84.
According to the theater interrogation reports all they were able to find on the Ki-84 was the prototype flight manual which was issued to the training unit.

Quite possibly that is what you had.
Do you have any more info?

The reports were that the 1st armed & armoured proto flew at 388mph. The 4th proto flew at 392mph.
That is official.
Then the interrogation teams interviewed
some engineers who said for the pre production version (which saw combat)
they changed the exhaust to individual stacks to give some extra power with their estimate (backed up by every other Japanese plane that used the technique) that it would give 9-10mph extra.

In my book that makes it 401mph armed and armoured. For the production version there are no surviving official papers, so again the engineers were interrogated.
The engineers stated that for the production Ki-84 the cowl was cleaned up and various other minor changes.
Those changes would probably add speed not subtract it.

The speed quoted in every book, game etc has to have a source; some of the early writers sourced the -THINTS others sourced earlier authors.
In my opinion that is a sloppy way to write a book or article.
392mph is only mentioned one(1) time in the official literature, for the 4th prototype. The first writers didn't have anything else to go on so the shrugged and said 392 sounds good. What else could they do?

However, many people if they hear something enough times they will decide it must be true. Sometimes mistakes are made...
There are still British pilots from WW2 that claim shooting down an He113...
do you think they really did?

The 4th proto Ki-84 used an 1800hp engine and that engine was also used in the initial production version.
The majority of Ki-84's were equipped with the 1990hp -21 or -25 engine however.

My guess is that the early production plane could do between 392-400mph with the standard operating fuel.
The model-21 engine planes could probably do between 401-414mph with
their fuel and engine problems.

Ki-84-2:
There was no recovered official papers for this plane. So the interrogaters continued with the engineers who stated semi-quote: The Ki-84-2 being a partly wooden plane was expected to be about 5mph slower than the Ki-84-1
and in pre production armed & armoured flew at 415mph at 20,000ft.

Again, the Ki-84-2 was equipped with the 1990hp engine.

So, with all of these pieces my thought is that with a good engine and 94 octane fuel the Ki-84 could fly 420mph.

408-410 would be a good number to use in a game for the 1990hp version.

I am not trying to step on anyones toes, i am just trying to share my thought process on this.
I have to have something to show for all of my time at NARA!

Michael

[Michael Johnson]

Oh, and i agree that the Ki-84 was an excellent plane in most ways better than the P51 or P47 (yikes! that is heresy! burn him!)
but the reason you might fly something else is because the Ki-84 was a dog over 23,000ft.

Useless against B29's. Or their escort fighters at high altitudes.

Much of the saved weight was because of the lack of a real supercharger.
In fact the supercharged version, which never went into production, was a slower aircraft.

Mike