Nakajima Ki-84

https://en.wikipedia.org/wiki/Nakajima_Ki-84

The Nakajima Ki-84 Hayate (?84 ?? Gale) is a single-seat fighter flown by the
Imperial Japanese Army Air Service in the last two years of World War II. The
Allied reporting name was "Frank"; the Japanese Army designation was Army Type 4
Fighter (????? yon-shiki-sento-ki). The Ki-84 is generally considered the best
Japanese fighter to operate in large numbers during the conflict. The aircraft
boasted high speeds and excellent maneuverability with an armament (up to two 30
mm and two 20 mm cannon) that gave it formidable firepower. The Ki-84's
performance matched that of any single-engine Allied fighter it faced, and its
operational ceiling enabled it to intercept high-flying B-29 Superfortress
bombers. Pilots and crews in the field learned to take care with the plane's
high-maintenance Nakajima Homare engine and a landing gear prone to buckling.
The difficulties of Japan's situation late in the war took a toll on the
aircraft's field performance as manufacturing defects multiplied, quality fuel
proved difficult to procure and experienced pilots grew scarce. Nevertheless, a
well-maintained Ki-84 was Japan's fastest fighter. A total of 3,514 aircraft
were built.

The design of the Ki-84 addressed the most common complaints about the popular
and highly maneuverable Ki-43: insufficient firepower, poor defensive armor, and
lack of climbing speed. The Ki-84 was a cantilever low-wing monoplane of
all-metal construction, except for the fabric-covered control surfaces. It had
retractable tailwheel landing gear. Armament comprised two fuselage-mounted,
synchronized 12.7 mm (.50 in) machine guns — these proved challenging to
synchronize properly with the Hayate's four-blade propeller — and two
wing-mounted 20 mm cannon, a considerable improvement over the two 12.7 mm (.50
in) machine guns used in the Ki-43 Hayabusa. Defensive armor offered Hayate
pilots better protection than the unsealed wing tanks and light-alloy airframe
of the Ki-43. In addition, the Ki-84 used a 65 mm (2.56 in) armor-glass canopy,
13 mm (.51 in) of head and back armor, and multiple bulkheads in the fuselage,
which protected both the methanol-water tank (used to increase the effectiveness
of the supercharger) and the centrally located fuel tank.

It was the Nakajima firm's own-designed 35.8 litre displacement, Ha-45 Homare
("Praise or Honor") air-cooled eighteen-cylinder radial engine, first accepted
for military use in 1941, that gave the Hayate its high speed and prowess in
combat. Derived from the Nakajima Homare engines common to many Japanese
aircraft, the Hayate used the Homare 21 direct-injection version of the engine,
using water injection to aid the supercharger in giving the Ki-84 a rated 1,491
kW (2,000 hp) at takeoff. This combination theoretically gave it a climb rate
and top speed roughly competitive with the top Allied fighters. Initial Hayate
testing at Tachikawa in early summer 1943 saw test pilot Lieutenant Funabashi
reach a maximum level airspeed of 624 km/h (387 mph) in the second prototype.
After the war a captured late-production example was tested in the US and
achieved a speed of 680 km/h (422 mph) using 92 octane AvGas, plus methanol
injection.


Role
Fighter

Manufacturer
Nakajima Aircraft Company

First flight
March 1943

Introduction
November 1944

Retired
August 1945 (Japan)

Primary user
Imperial Japanese Army Air Service

Number built
3,514

Variants
Nakajima Ki-116

The first major operational involvement was during the battle of Leyte at the
end of 1944, and from that moment until the end of the Pacific war the Ki-84 was
deployed wherever the action was intense. The 22nd Sentai re-equipped with
production Hayates. Though it lacked sufficient high-altitude performance, it
performed well at medium and low levels. Seeing action against the USAAF 14th
Air Force, it quickly gained a reputation as a combat aircraft to be reckoned
with. Fighter-bomber models also entered service. On April 15, 1945, 11 Hayates
attacked US airfields on Okinawa, destroying many aircraft on the ground.

In the final year of the war the Ki-84, the Ki-100 (essentially a radial-engined
version of the inline-powered Kawasaki Ki-61) and Kawanishi's N1K2-J were the
three Japanese fighters best suited to combat the newer Allied fighters.

Specifications (Ki-84-Ia)

General characteristics
Crew: 1
Length: 9.92 m (32 ft 7 in)
Wingspan: 11.238 m (36 ft 10 in)
Height: 3.385 m (11 ft 1 in)
Wing area: 21 m2 (230 sq ft)
Airfoil: root: NN-21(16.5%) ; tip: NN-21(8%)
Empty weight: 2,660 kg (5,864 lb)
Gross weight: 3,601.5 kg (7,940 lb)
Max takeoff weight: 4,170 kg (9,193 lb)
Powerplant: 1 × Nakajima Ha-45-23 Homare Models 11,12,21 or 23 18-cylinder
air-cooled radial piston engine, 1,522 kW (2,041 hp)
Propellers: 4-bladed constant-speed metal propeller

Performance
Range: 2,168 km (1,347 mi, 1,171 nmi)
Service ceiling: 11,826 m (38,799 ft)
Rate of climb: 21.84 m/s (4,299 ft/min) at sea level
18.29 m/s (3,600 ft/min) at 3,050 m (10,007 ft)Wing loading: 171.47 kg/m2 (35.12
lb/sq ft)
Power/mass: 0.41 kW/kg (0.25 hp/lb)

Armament

2× 12.7 mm Ho-103 machine guns in nose, 350 rounds/gun
2× 20 mm Ho-5 cannon in wings, 150 shells/cannon
2× 100 kg (220 lb) bombs
2× 250 kg (551 lb) bombs
2× 200 L (53 US gal) drop tanks



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