Battle of the Philippine Sea-Technology


An enlisted plotter annotates the transparent vertical summary plot in an Essex Class carrier combat information center.


U.S. Naval Institute Photo Archive – Officers and men in the USS Lexington (CV-16) work over a plotting table in the carrier’s radar plot spaces while operating off Formosa in 1945. During the series of Navy raids on Formosa that month, Lieutenant Monsarrat was in the same area on board the Langley (CVL-27) when a Japanese bomb crashed through her deck.

The key to the Battle of the Philippine Sea would be less gunnery and torpedo work per se, but much more general proficiency in air and anti-­air warfare. This had three dimensions: (a) the quality of the two sides’ aircraft and pilots; (b) the techniques of fighter control used; and (c) the quality of the anti-aircraft gun defence systems on both sides. These will be discussed in turn. One important point, however, ought to be reiterated. Often anti-air warfare is seen purely in terms of `air defence’. In fact, the capacity of a fleet to destroy the aircraft attacking it is an important part of its offensive fighting capability. Drawing the enemy into making air attacks is like drawing out his surface units. If they expose themselves by attacking, they make themselves subject to engagement, engagement moreover where the Clausewitzian advantages of the defender are on the side of the forces being attacked. The destruction of an attacking air fleet is an offensive fleet engagement like any other.

Quality of Aircraft and Pilots

The Americans were in a much better situation than the Japanese with respect to both aircraft and pilot quality. The standard US Navy fighter, the F6F-3 Hellcat, was slightly faster than the `Zero’ in its latest A6M5 version at 375mph against 350. The F6F was heavier and more robust with an engine of almost twice the power. Its six 0.5in heavy machine­guns could inflict terrible damage on the lightly built Japanese machines. The `Zero’ was quite well armed with two 20mm cannon and three machine-guns but lacked both armour and self-sealing fuel tanks. Only the latest A6M5b versions carried by Chitose, Chiyoda and Zuiho had armoured glass windscreens and automatic fire-extinguishers. Japanese fighter advantages were in maneuverability and rate of climb, but the Japanese fighter pilots were in no position to exploit these characteristics. Japanese training had suffered badly through fuel shortages and the need to replace the heavy casualties of 1942-44. During the winter of 1943-44 advanced combat training had been abandoned for the best pilots coming out of elementary/intermediate training, and although this decision was reversed in the spring of 1944, the damage had been done. Many potentially good pilots had been killed prematurely on operations. A very large proportion of the Japanese pilots in First Mobile Fleet were fresh out of training school with little, if any, combat experience. The average Japanese naval pilot had only 275 hours of flying time compared with 525 for an American.

A major reorganization of Japanese air groups had been undertaken in February 1944. Air groups had been formed for groups of carriers. Air Group 601 covered the fleet carriers Taiho, Shokaku and Zuikaku. It consisted of skilled survivors of previous battles, seaplane pilots and freshly trained personnel. It had been able to carry out training at Singapore but the inability to carry out flight operations around the Tawi­-Tawi base caused a degradation of flying skills. Air Group 652 covered Junyo, Hiyo and Ryuho and had suffered serious attrition in the fighting around Rabaul in early 1944. The replacements for these losses were hastily gathered together in Japan where fuel was short. The `Zero’ fighter-bombers were flown by bomber pilots with little, or no, air combat experience. The combat capability of the group was considered to be `modest’. Again, deployment to Tawi-Tawi prevented any further training in the period just prior to the battle. Air Group 653 (Chitose, Chiyoda and Zuiho) was in almost as bad shape. The majority of its pilots were of the September 1943 or January 1944 graduating classes, probably mainly the less able members of these groups who had received advanced training but who had had no combat experience. Average pilot training times for each group were six months for 601, two months for 652 and three months for 653. Before the war pilots had averaged forty-two months of training!

All this was bad enough, but the Japanese aircraft depended on the superior pilot skill that had been displayed by the first generation of Japanese pilots in the months after December 1941. Both the new Yokosuka D4Y-i Suisei (`Comet’) dive-bomber (Allied code-name `Judy’) and the Nakajima B6N-i Tenzan (`Heavenly Mountain’) torpedo-bomber (`Jill’) were fast and maneuverable, being significantly lighter than their US counterparts. The `Judy’ had a loaded weight to power ratio of only 6.9lb/hp and the `Jill’ only 6 compared with their American counterparts’ 7.4 and 8.6. Their range was also significantly better, but they were also harder to fly. The Japanese were also still using a higher proportion of older aircraft of the first war generation, both the ‘Val’ dive-bomber and `Kate’ torpedo-bomber. The latter in particular combined poor protection and performance by 1944 standards.

The American air groups were combat-hardened veterans who had emerged from a richly endowed training programme back in the USA. US pilots had 300 hours of flying before carrier assignment and 24 months or so of training before entering combat. Many had been in combat for ten months and their aircraft were suffering, being in need of overhaul and with fuel consumption higher than normal. This exacerbated the Americans’ disadvantage in combat range. The Avenger torpedo-bomber was, however, relatively fast and well-armed and armoured. The Helldiver dive-bomber was even faster than the Avenger and could absorb much punishment, but it was not as maneuverable as its slower but well liked predecessor, the SBD-5 Dauntless, which was still in service in TG58.3 and in small numbers in Yorktown. Given the Japanese inability to exploit the good features of their aircraft, for which their designers had sacrificed other desirable qualities, they were outmatched both qualitatively and quantitatively in the air. American problems were marginal by comparison.

Fighter Control

By June 1944 the Americans had a well-established system of Combat Information Centres (CICs) where radar operators plotted enemy raids on cathode-ray tubes with range and bearing indicators. They then passed this information to plotters who put the target on a plexiglass display. Raids were numbered and the position of friendly fighters shown. The status of all the fighters being controlled by a particular ship was placed on another display. The fighter direction officer observed both boards and allocated fighters to intercept the incoming raids, guiding them into position by VHF radio. There was a Task Force fighter director (FD) officer in the TF58 flagship in touch with the five Task Group fighter director officers. These in turn were in touch with the FD officers in each carrier. The director allocated raids to the TGs and the latter raids to individual ships. The system was an advanced and integrated one and worked remarkably well. The electronic hardware on which it was based comprised SC or SK search radars which worked at a frequency of 400mHz; range was 60-100 miles respectively and bearing error was 2° at 100 miles (7 miles). SM fighter control radar, carried in carriers, gave height information and also indications of the composition and vertical formation of the attackers. High-frequency SG surface search radar (3,000mHz) could give warning of low-altitude torpedo-bomber attacks.

The Japanese were much less well equipped in this vital regard. Their fighter director officers seem to have worked more or less straight from the radar consoles, giving instruction by radio. The main Japanese air warning radar was the Type 2 with a frequency of 200mHz. It was of low power, which limited range to 50 miles at best. Bearing error was 5 degrees at such range. A still lower frequency radar of higher power, similar range but lower accuracy, the Type 3, was also used.

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