Question about Ki-84 Testing at Wright Field

[BuzzLightyear]

One of the Ki-84's (given Foreign Evaluation number FE-302 then T2-302) captured at Utsunomiya South military airfield in Japan in 1945 was shipped to and tested at Wright Field, apparently against a P-47D and a P-51D. The plane reached a top speed of some 427 mph. This is well in excess of published speeds. What gives? I know the plane was overhauled at Middleton Air Depot before going to Wright Field for testing, but it wasn't modified.

Anyone have any ideas as to why this plane was so much faster than published specs? Anyone have a copy of the report?

http://members.cox.net/rowlandparks/t302.jpg

[GregP]

That would be really nice to know! One potential factor was probably American gasoline. The stuff the Japanese and the Russians were using in the last year or two of the war was probably no more than 80 - 85 Octane.

I certainly don't claim this as THE factor, and I haven't seen the report, but well-filtered, 100+ OCtane fuel probably contributed to a good-running powerplant that was probably free from detonation for the first time since it was built.

I always thought the Ki-84 was the best Japanese fighter of the war.

[Romantic Technofreak]

Although I personally also like the Hayate most, literature tells about two serious rivals:

1. The Kawasaki Ki-100

http://www.xs4all.nl/~fbonne/warbirds/ww2htmls/kasaki100.html

The Ki-100s performance seems to be somewhat lower than the Ki-84s (580 to 630 kph), but it is flown with a 500hp lesser engine. Given the Ki-100 an engine of 2.000 hp, ist should run estimated 649 kph! Looks like other engines would not fit to the fuselage, formerly designed as Ki-61 with narrow inline engine.

2. The Kawanishi N1K Shiden

For arguments (See Steve Lange´s, scroll down):
http://aeroweb.brooklyn.cuny.edu/specs/kawanish/n1k2j.htm

For nice picture:
http://www.angelfire.com/fm/compass/N1K.htm
(Note the mistake that the Shiden is driven by a RR Merlin inline engine. Obviously from captured Australian Spitfires, the cylinders are wound around the central axis to form a radial:D)

With equal engine performance, the Shiden runs only 595 kph, for me this performance is already obsolete for 1944/45. Inspite of this, the Shiden often is considered "best Japanese Navy fighter".

I never heared well-founded arguments (like I am used to listen to in this very forum) about a performance comparison between these Japanese fighters, although they often are considered as "superior" to their Allied opponents, were there not the restraints of fuel, production, crew education and mechanic education quality. I don´t have the entire "Best fighter" discussion thread in my head, but as much as I remember these planes don´t come up there, while following the superiority argument them must have been the best piston-engined fighters of WWII.

Personally I may disagree, but given Buzz´s observation above and Greg´s solution by just using some more octane the situation may look differently. I only can say these planes at least came one or two years too late. If Ki-84s had manned Japanese aircraft carriers early enough, who knows what might have been?

[robert]

In Rene Francillon's Japanese Aircraft of the Pacific War, he notes that the speed of 427 mph was achieved "at 20,000 ft using War Emergency Power." This would indicate some kind of a boost; of exactly what type, I'm not sure.

In his Profile on the Ki-84, Francillon directly quotes the Wright Field report, so he must have had access to it. Here's the report's conclusion:

"It is believed that the 'Frank-1' is a fighter aircraft with excellent manoeverability and handling qualities and a good rate of climb for its type. The light power loading and control forces are admirable, although its lack of pilot protection and short range leave much to be desired in the light of present fighter standards."

The Wright Field Ki-84 was fitted with an Ha-45-21 engine, giving 1,970 hp at 3,000 rpm, and a War Emergency Rating of 2,050 hp at 2,500 ft. The Wright Field Test results were as follows (from the Profile):

Maximum speed:
363 mph at sea level
427 mph at 20,000 ft
360 moh at 35,000 ft

Cruise speed:
254 mph at 1,500 ft

Climb rate:
4,275 ft/min

Ceiling:
38,000 ft

Normal range (internal fuel 184 US gallons):
780 m at 254 mph

Maximum range (plus 174 US gallons additional fuel):
1,845 m at 173 mph.

Assuming that "m" stands for "miles" in the range, I don't see how 1,845 miles can be seen as short-ranged!

Phil Butler's War Prizes gives the following information on FE-302/T2-302, one of two Ki-84s captured at Utsunomiya South Military Airfield and shipped to Wright Field:

"This 'Frank' was shipped to the USA abord the USS Barnes and was handed over to the USAAF on 7th December 1945...After restoration work at Middletown, FE-302 was test flown on 16th May, 1946. On 20th May it was delivered to Patterson Field, flying onwards to Wright Field on 27th May. After a further 8 hours of flight tests at Wright Field, it was flown to Park Ridge on 3rd July 1946 for the proposed Air Museum. The Flight Test report concluded that the type compared favourably with the NA P-51H and Republic P-47N. The type was criticised for its short range and lack of armour. It was also noted that the flight test programme had been hampered by frequent failures of the engine exhaust stacks due to the use of poor material, poor welding techniques and bad detailed design of the method of suspension. The series of Flight Test Reports was issued under Project No. NAD-25, with references in the series F-1M-1119-ND. There is no record of this aircraft after its arrival at Park Ridge, and it was probably scrapped when the depot was reactivated during the Korean War."

[GregP]

Thanks for the details on the Frank!

The Ki-84, the Ki-100, and the Shinden-Kai (the low wing version), were very good aircraft, if a little slower than than the best the Allies had to offer.

Their workmanship quality was always good, but the metallurgy suffered from Allied bombing, and directly affected the combnat effectiveness of the otherwise-good airframes. The quality of their pilots also deteriorated, as has been discussed in earlier threads.

Still, a well-flown Ki-84, Ki-100, or Shiden-Kai could hold its own against any opposition ... unless it was simply overwhelmed by numbers. And that was the case in 1945.

The Japanese culture made defeat a thing to be ashamed of, and they did very little to keep the history of their aircraft industry documented after WWII. Today, we have very little in the way of historical documents to tell us much of what the Japanese aricraft industry developed and how the testing went.

Some years back, the Russian Yakovlev bureau was talked into producing some new-build Yak-3s (with Allison engines ... for serviceability concerns) for a few wealthy pilots. I would love to see Mitsubishi, Kawasaki, and Fuji (Nakajima) produce some new-build Japanese fighters for us to see! ... possibly with Pratt & Whittney radials ...

[BuzzLightyear]

Robert, I have both those books and I'm aware of the history given in War Prizes. I have an original copy of Francillon's book, and also of the later reprint, and I can't find that test performance summary anywhere in them. Can you give me a page number? Thanks.

[robert]

quote:Originally posted by BuzzLightyear

Robert, I have both those books and I'm aware of the history given in War Prizes. I have an original copy of Francillon's book, and also of the later reprint, and I can't find that test performance summary anywhere in them. Can you give me a page number? Thanks.


Perhaps I was unclear that I was referring to two different books by Rene Francillon.The comment about the the speed of 427 mph being obtained using Emergency War Power is from Japanese Aircraft of the Pacific War, 1987 edition (the one with the painting of the H8K on the cover), page 236.

The quote from the Wright Field report and the figures from that report are from the same author's entry in the old Aircraft in Profile series, Aircraft Profile #70, Nakajima Ki-84. My copy is the March 1982 reprint, and the pages are un-numbered, but it's only twelve pages long, and the quote from Wright Field is on page 10, and the test figures are in the second column from the left in the "Specifications" table on the back page. In the collected Aircraft in Profile hardbacks, the Ki-84 is in Volume 3.

Hope that helps!

[BuzzLightyear]

Ok, gotcha. Thanks for the clarification. I don't have the Profiles book.

[ickysdad]

Any new info on this subject? Anywhere I can get a copy of that report?

[Trexx]

You know, I've got this gigantic book, "Great Planes of World War Two" that features reports of American fighters being tested in mock air combat to a myraid of Japanese fighters. I'll take it off the bookshelf and see if that report is featured. Stand - by.

[ickysdad]

quote:Originally posted by Trexx

You know, I've got this gigantic book, "Great Planes of World War Two" that features reports of American fighters being tested in mock air combat to a myraid of Japanese fighters. I'll take it off the bookshelf and see if that report is featured. Stand - by.

One maynot realise that the 427 MPH figure is probably an estimated value . Rene Francillion's book states that at that speed which was at 20,000' was obtained at a wieght of 7490 lbs. when the normal load was 7955 lbs. most probably a low fuel,no ammo loadout. He also states that at that altitude it was 3 MPH faster then the P-51 & 22 MPH then the P-47 at that altitude HOWEVER thier speeds were obtained at factory settings and 100 grade fuel from an earlier point in the war while the K-84 had a reconstructed engine (that could use over-boost) using a Hamilton Standard propellor further it was modified to use 150 grade fuel . The USAAF fighter figures were also with wing racks fitted which will slow them down some. There was no side by side compariosons/tests involved as many down throough the ages have been lead to believe.
So always read the fine print when looking at compariosns.