Here is some good stuff regarding the Oscar and Ki-44 Shoki (Tojo) as well:
Date: 09 Mar 1998
Newsgroups: rec.aviation.military
Date: 09 Mar 1998
Newsgroups: rec.aviation.military
The Ki-43 was, in some ways, more dangerous to deal with than the A6M, chiefly
because it had a better rate of roll and was armed with two 12.7mm machineguns.
The P-40 driver with a Zero on his tail could usually break the contact with
an aileron roll. This was much less likely with the Ki-43. The Oscar boy
could plant himself behind the P-40 and stay there no matter what the Curtiss
driver did, all the while hammering .50 cal nails that could do some real
damage.
In contrast, the Zero pilot, even if he couldn't be shaken, was doing most of
his firing with rifle caliber mgs which did less damage (although enough of
them in the right places could do the job). The 20mms generally didn't come
into play unless the Zero was in point blank range. A way to stay out of
point blank range was to execute a series of violent aileron turns; this would
allow the P-40 pilot to gradually pull away from the Zero. Once he had
extended sufficiently, he could go into a fast, shallow climb and leave the
Zero behind.
The best bet for the P-40 driver was to have sufficient altitude to dive away
from either the Oscar or Zero, but that wasn't always the situation.
The Ki-43 had better wing loading and power loading than the Zero, had superior
initial acceleration, a better roll rate and a tighter turning circle. It also
had a substantially better rate of climb. That made it an awesome aerobatic
fighter that you absolutely, positively did not dare engage in a dogfight. It
also meant that if you bounced an Oscar and the pilot spotted you, he was
probably going to escape scott free because, should he choose to turn, he could
roll into a tight turn faster than you could follow, whereas if you bounced a
Zero, should he choose to turn, you could follow him, outrolling him and
staying with him for a considerable portion of his turn, often enough to do him
in. (In practice, Oscar and Zero drivers both generally preferred to snap up
into tight loops when bounced, leaving the P-40 driver the option of blowing on
by and clearing the vicinity or sticking around to get a Nip on his six.)
In a typical scenario early in the game, P-40s could be flying top cover for
B-26s flying at 9,000 ft. that were attacking an airstrip, note Oscars taking
off below, make a turn away from the B-26s to position themselves up-sun to
dive on the Oscars once they approached the bombers, turn and come back, taking
less than three minutes for the entire maneuver, and find the B-26s already
under attack from those Oscars they had seen just taking off. Amazing little
buggers.
P-40 escort quickly learned to dive on any Oscars they spotted, no matter how
far below they were, and the bomber boys had to learn not to howl when they saw
their escort peel off for the deck, even though there were no Jap planes
anywhere close by.
The chief advantages of the Zero over the Oscar besides the two 20mm cannon
were a somewhat faster maximum speed and a much, much greater range. Since the
P-40 was faster than the Zero, its superior speed to the Ki-43 wasn't too
important. Range was, because it meant that Zeros could be encountered almost
anywhere at anytime. That was a key reason they were so dangerous.
The Ki-61 was a very serious airplane, no doubt, and was by no means a rare
fighter in New Guinea, being routinely encountered from about mid-1943 on. The
Ki-84 wasn't encountered until the second PI campaign. Definitely a topflight
performer.
Not to be overlooked is the Ki-44, the performance of which was more or less
comparable to the FW 190A series, but with a faster rate of climb. It was met
over the oil refineries in the Dutch East Indies and was used in China and was
quite formidable. The P-40 was simply outclassed by it, and had the Japanese
Army pushed Ki-44 units into New Guinea in 1942, it would definitely been bad
news for the allies. In the nearly failed Buna campaign (the US 32nd Infantry
Division suffered 90 percent casualties, the worst rate of the entire war) in
late summer, for example, the chief allied fighter was the P-40, Es flying
escort for Ks which were used as dive bombers. The P-40s flew three and four
missions a day, desperately fighting to stave off disaster on the ground. No
way the old E could have handled the Ki-44. The Ki-44 could have cut a wide
swath through New Guinea at just the right time--pre-P-38. Apparently, the
JAAF considered holdings in the DEI, Manchuria and CBI more important than
Australian New Guinea, so reserved the Ki-44s to protect them, leaving the
Ki-43 to handle the "North of Australia Front" that the navy had gotten it
entangled in, then choosing to supplement the Ki-43 with the Ki-61, which fell
prey to the P-38.
The Ki-44 was replaced by the Ki-84, theoretically a good move, but it might
have made more sense to keep the Ki-44 in production anyway, perhaps shutting
down Ki-43 production at Tachikawa replacing it with Ki-44 production.
Tachikawa built Ki-43s until the end of the war; Nakajima itself stopped
building Ki-43s in Oct., 1944 and ended Ki-44 production in favor of Ki-84
production in Dec., 1944.
It's worth pointing out that while the Japanese Navy stuck pretty much with the
A6M manuever fighter, the Japanese Army went from the Ki-43 maneuver fighter to
the Ki-44, Ki-61 and Ki-84, all energy fighters.
As the USAAF introduced superior fighers, so did the JAAF. When an American
Army pilot was flying the P-40, he met the Ki-43. He got the P-47 or the P-38
and he met the Ki-44 and Ki-61. He got the P-51 and he met the Ki-84. When
the USN/USMC pilot was flying the F4F, he met the Zero. When he was flying
the F6F he met the Zero. When he was flying the F4U, he met the Zero. It's
another point of superiority of the JAAF over the JNAF that is largely
overlooked.
It's certainly true that the Ki-43 was kept in production long after its
virtues had largely become irrelevant or surpassed(true, too, of the Zero), but
that can be said as well of the Me 109 and, for that matter, the P-40. It's
worth remarking that while neither Messerschmitt nor Curtiss ever came up with
a better single-engine piston fighter than the one they started the war with,
and just monkeyed around with their original design, Nakajima came up with two
entirely new fighter planes, each substantially superior to its predecessor.
