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Aircraft


Photograph of A6M Zero launching for the Pearl Harbor
        attack

National Archives

Like the tank, the aircraft was a weapons system that was introduced in the First World War and proved decisive in the Second. Aircraft had an unprecedented level of mobility, but only within their combat radius of a friendly base. Much of the strategy of the Pacific War was directed towards capturing new bases from which air power could be projected ever deeper into enemy territory.

The aircraft of the Second World War were almost exclusively metal-skinned piston monoplanes. A few fabric-covered biplanes saw service early in the war, and jet aircraft were introduced towards its end, but none of the latter saw service in the Pacific. Metal construction meant greater structural strength, while piston engines evolved to near their practical technological limit, yielding speeds of better than 400 miles per hour. Firepower also increased, from the dual 0.30 machine guns of the biplane fighters of the First World War to eight 0.50 machine guns or four 20mm cannon on the most heavily armed fighters of the Second World War. Bomb loads increased to 20 tons on the B-29 Superfortress, which also had a range of over 3000 miles.

The two sides had different aircraft design philosophies. Japanese aircraft were optimized for offensive fighting power and emphasized range, firepower, and maneuverability at the expense of ruggedness and protection. This led to deficiencies such as the almost complete lack of self-sealing fuel tanks, which made many Japanese aircraft fire traps. Few Japanese aircraft had any significant amount of pilot armor. Allied aircraft were much better protected but could not match the maneuverability of Japanese aircraft. However, second-generation Allied aircraft had powerful enough engines to catch up with the speed of Japanese aircraft while remaining rugged and well-protected.

The weaknesses of Japanese aircraft were pointed out in a 17 April 1942 conference at Rabaul convened to review the lessons of I-Go. Ugaki chaired the conference while Yamamoto silently observed. There was considerable discussion of the tendency of Japanese aircraft to catch fire after just a few hits. The Japanese were reluctant to admit the problem, preferring to attribute aircraft bursting into flame as jibaku, pilots deliberately blowing up their planes as a symbolic act of suicide. However, the conference concluded that there was more need for "bullet protection", and subsequent Japanese aircraft designs did in fact put a greater emphasis on protection. However, the new designs by and large went into production far too late to make much difference.

Another peculiarity of Japanese aircraft was the very poor communications equipment. The Japanese Navy did not acquire the capability to manufacture and install radios in its aircraft until 1940. Production was 1000 long-range HF sets and just 100 short-range radiotelephone sets per month in 1942. Each fighter was to be retrofitted with a radiotelephone and each light bomber with a radiotelephone and HF set, but the sets were poorly installed and almost unusable. The designs were so compact that they had a tendency to overheat and suffer early component failure. Many fighter pilots later discarded their sets as so much useless extra weight. The Japanese sometimes compensated for their inferior radio equipment by dropping powder markers from light bombers, which carried a navigator, to help guide their fighters back to their carriers. The powder markers took the form of solid cone-shaped silvery pellets that could be dropped in a line over the ocean and which melted to form a line of reflective patches on the ocean's surface.

Japanese air tactical doctrine emphasized radio silence in any case. Communication by radio was permitted only to report an attack, to order an attack, or to report sightings of significant enemy units. The resulting low volume of communications required only a single crystal-controlled radio channel. However, radio doctrine began to change after the Japanese began to appreciate the significance of radar, which ensured that maintaining radio silence did little to achieve surprise. The single channel was also vulnerable to jamming by the Allies, though this was sometimes deliberately avoided to permit intelligence officers to eavesdrop on Japanese communications.

Japanese radio equipment began to show significant improvement later in the war. By late 1943 the Japanese had begun manufacture of the Navy Type 3Ku Mark 1 Wireless Telephone, which was modern, well designed, and well constructed. Japanese crystals were of good quality and the U.S. Air Force considered Japanese voice microphones superior to their own.

In general, Allied intelligence found Japanese instruments, navigation equipment, and oxygen apparatus to be of good quality, and occasionally innovative. However, Allied intelligence was not impressed with the quality of parachutes.

Communications problems were not exclusive to the Japanese. American pilots made much heavier use of voice radio than the Japanese, often showing very poor radio discipline.  Yet poor radio communications dogged the Americans as late as the Battle of Santa Cruz and probably contributed to the slaughter of the torpedo bombers in the Battle of Midway. American radios of 1941 were equipped with a "coffee grinder", a small hand-cranked frequency tuner that was tedious for pilots of single seat aircraft to work. However, American radio communications even at their worst were superior to those of the Japanese, and improved markedly later in the war. By mid-1943, the Americans had equipped their carrier aircraft with the excellent AN/ARC VHF radio, which was equipped with eight push-button preselected channels. These were marvels of miniaturization for their day, packing some 4600 components into a box 29" by 19" by 9" (74cm by 48cm by 23 cm). Long-range bombers were equipped with the SCR-287, a 75-watt radio capable of long-range voice or key transmission.

An important aspect of air power was aircraft availability. When an air unit was out of combat and it was known that an important operation was pending, it was possible to bring as many as 80% to 90% of the aircraft in the unit to full mission capability. Under conditions of continuing combat, this percentage dropped. Typical availability was 50-70% for U.S. forces and sometimes less than 30% for Japanese forces at forward bases. This was partly a function of environment, and an availability of even 50% required an exceptional effort for U.S. forces early in the jungle war in the South Pacific. More complex aircraft tended to have a lower availability rate: At the start of the Rabaul air offensive of 1942, availability percentages were 92% for P-40s, 91% of F6Fs, 66% for F4Us, and just 38% for the complex P-38s.

Aircraft Types

Aircraft could carry out a variety of missions, but no single aircraft design was effective at all missions. Most aircraft fell into one of four broad categories, though these had significant overlap.

Reconnaissance Aircraft. The original air mission, reconnaissance is the collection of intelligence by direct observation. While all aircrew were capable of eyeballing the area in which they operated, some aircraft were specifically designed for this role.

Fighters. The introduction of reconnaissance aircraft in the First World War naturally led to the development of fighter aircraft to gain control of the air or deny control of the air to the enemy.

Bombers. Because of their mobility, aircraft could rapidly concentrate firepower at crucial points. In addition, aircraft had a shock value similar to that of tanks. Bomber aircraft were optimized to deliver firepower against surface targets.

The equipment and doctrine of naval air forces naturally emphasized strikes against enemy shipping, but carrier raids against shore targets were also anticipated. American naval aircraft were regularly committed to direct ground support missions, but it was only late in the war that the Americans mastered the art of close air support, which is the form of direct air support in which attacks are carried out against targets immediately in front of friendly forces.The jungle was particularly difficult terrain in which to distinguish friend from foe, and there were friendly fire incidents at New Georgia in spite of the tendency for direct air support to be directed against targets well to the Japanese rear.

Transport. Although transport by air was the most expensive way to move men, equipment and supplies, it was also the fastest and most flexible. Transport aircraft were particularly important in areas lacking normal infrastructure, including many areas of the Far East and Pacific.

In addition, trainer aircraft were required to train aircrew.

Lists of aircraft that participated in the Pacific War can be found under their aircraft types.

Aircraft Specifications

The aircraft specifications given in this Encyclopedia have the following meanings.

Crew. The crew of a combat aircraft varied from a single pilot in most fighter aircraft to 13 in the B-17 Flying Fortress. Light bombers typically had a crew of two, consisting of a pilot and radio operator/rear gunner. Some kinds of light bombers, including most torpedo planes, could carry an additional observer or gunner. Medium and heavy bombers typically had two qualified pilots, a navigator, a bombardier, a flight engineer, and a variable number of additional gunners. The non-pilot specialists usually manned a gun when under attack.

Dimensions. These are the wingspan, length, and height. The dimensions were particularly important for carrier aircraft, which had to be able to fit onto the elevators and under the overhead of the hangar deck. The dimensions also determined how many aircraft could fit onto a carrier flight deck for a deckload strike. Some carrier aircraft had folding wings to save space.

Wing area. In general, a greater wing area means better low-speed maneuverability and lower takeoff and landing speeds, but at the cost of a reduction in maximum speed. The usual comparison figure is the wing loading, which is the ratio of weight to wing area.

Weight. Usually the empty and fully loaded weights are given. The heavier the aircraft, the more lift was required to keep it in the air. More lift was achieved either by increasing the wing area or by increasing the cruising speed. A light load usually increased an aircraft's range.

Maximum Speed. This specifies the maximum speed the aircraft could achieve in level flight, and the altitude at which this speed was reached. At lower altitudes, the denser air produces more drag, while at higher altitudes, the engine efficiency begins to suffer in the thinner air. Most aircraft of the Second World War had engines equipped with some kind of supercharger to compensate for the thinner air at altitude. Those few that did not had poor high-altitude performance, sometimes to such an extent that their best speed came at sea level.

Cruising speed. This is the speed at which the aircraft achieved its optimal range.

Landing speed. This is approximately equal to the stall speed at sea level. The greater the landing speed, the longer the runway required.

Climb rate. This is a measure of how quickly the aircraft could gain altitude. It is an important performance specification for fighter aircraft. Since climb rate dropped as altitude increased, we give an average climb rate from sea level to normal operational altitude.

Service ceiling. This is the altitude at which the rate of climb drops below 100 feet per minute. It marks the maximum practical altitude at which the aircraft can operate.

Power plant. This indicates how many engines the aircraft has, and of what type. Almost all aircraft that saw combat during the Pacific War were equipped with either radial or inline piston engines. Radial engines were air-cooled, which made them less susceptible to combat damage and allowed them to produce more power per unit weight. On the other hand, inline engines had a much smaller cross-section, which usually reduced drag enough to compensate for their greater weight.

Armament. This varied greatly between different aircraft types, but usually consisted of some number of machine guns or cannon. These were either fixed to the airframe, so that they were aimed by pointing the entire aircraft, or they were mounted in flexible mounts or turrets, where they were aimed by gunners. Rifle caliber (0.30 or 7.7mm) machine guns were often used early in the war, but gave way to 0.50 caliber (12.7mm) weapons or cannon that packed more punch. Cannon fired an explosive shell, usually 20mm but sometimes as large as 40mm, which could do a great deal of damage; but cannon also had a lower rate of fire, so that 0.50 caliber machine guns remained competitive with cannon almost to the end of the war.

Some Allied strafing aircraft carried a single 75mm gun. These were useless in aerial combat but could be effective against ground targets.

Bomb load. This describes the stores that could be mounted on the aircraft's hard points or in its bomb bay. These stores included bombs, rockets, and torpedoes, but also fuel drop tanks for extending the aircraft's range or airborne radar pods.

Range. The range of an aircraft is the maximum distance it can fly before it must land to refuel. It differs from the combat radius, which is the maximum distance from its base that an aircraft can successfully perform its mission. The rule of thumb is that combat radius is about one-third of total range. This means that the aircraft expends one-third of its fuel reaching the target, up to one-third of its fuel maneuvering near the target, and one-third to return home. Aircraft occasionally operated at close to half their range, but this put them at a serious disadvantage because there was no fuel reserve for combat maneuvers.

Fuel. The maximum amount of fuel carried internally by the aircraft. Where more than one figure is given, these specify different internal storage locations, such as wing or fuselage tanks. Fuel capacity of drop tanks is listed under bomb load.

Capacity. For transport aircraft, this lists the number of passengers or weight of cargo the aircraft could carry.

Sensors. Describes any special sensors the aircraft carries, such as radar or magnetic anomaly detectors.

Production. This summarizes how many of the aircraft were produced, and over what time period. In the case of Allied aircraft, a large fraction of production went to Europe rather than the Pacific. The fraction of production reaching the Pacific varied from less than 20% for the A-26 to essentially 100% for the B-29 and some of the Navy models.

Variants. Most aircraft models were refined and improved over the course of their production run, so that more than one variant saw combat. In addition, some aircraft models were modified to fill specialized roles. For example, certain variants of the A-20 were produced with transparent noses for a bombardier, so that they could serve as bombing lead ships in Europe.


Japanese aircraft guns

7.7mm Type 89

7.7mm Type 89 Model 2

7.7mm Type 92

7.7mm Type 97

7.92mm Type 98

7.92mm Type 1

12.7mm Type 1

13mm Type 2

13.2mm Type 3

20mm Mauser

20mm Type 97

20mm Type 99

20mm Type 1

30mm Ho-155

30mm Type 5

37mm Type 98

37mm Ho-203

40mm Ho-301

57mm Ho-401

Allied aircraft guns

0.30 Browning

0.50 Browning

20mm Hispano

0.303 Vickers K

37mm M4

40mm Vickers Class S

75mm M4



References

Bergerud (2000)

Francillon (1979)

Gamble (2010)

"Handbook of Japanese Military Forces" (1944-9-15)

Klein (2013)

Mikesh (2004)

Tillman (1979)

Werneth (2008)

Zimm (2011)



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