POWER PLANT: One Pratt & Whitney R-1830-56 radial engine, rated at 1,350 hp
PERFORMANCE: 320 mph
COMMENT: Grumman’s F4F “Wildcat” production ceased in early 1943 to make way for the newer F6F “Hellcat”, but General Motors/Eastern Aircraft continued producing “Wildcats” for both U.S. Navy and (British) Fleet Air Arm use. At first, General Motors produced the FM-1 (identical to the F4F-4, but with four guns). Production later switched to the improved FM-2 (based on Grumman’s XF4F-8 prototype, informally known as the “Wilder Wildcat”) optimized for small-carrier operations, with a more powerful engine, and a taller tail to cope with the increased torque.
From 1943 onward, “Wildcats” equipped with bomb racks were primarily assigned to escort carriers for use against submarines and attacking ground targets, though they would also continue to score kills against Japanese fighters, bombers and kamikaze aircraft. Larger fighters such as the “Hellcat” and the Vought F4U “Corsair” and dedicated dive bombers were needed aboard fleet carriers, and the “Wildcat’s” slower landing speed and its size made it more suitable for shorter flight decks of escort carriers.
General Motors / Eastern Aircraft produced 5,280 FM-1 and FM-2 variants out of total production of 7,860 “Wildcats” (Ref.: 24).
POWER PLANT: Two BMW 003 turbojet engines, rated at 900 kp each
PERFORMANCE: 553 mph at 16,405 ft
COMMENT: This Blohm & Voss dive bomber and ground attack aircraft project of 1944 was of a twin boom design with each boom having a bomb bay in the forward section capable of holding a SC 250 bomb. The aircraft was powered by two BMW 003 turbojet engines mounted side-by-side under the center nacelle in which the cockpit and armament was located. The heavy armament consisted of four fuselage mounted MG 151/20 20mm cannon. The landing gear was a conventional “tail-dragger” arrangement with extended track width. Although detail planning was in advanced stage the project was not favored by the “Technische Amt” (Technical bureau) of the RLM (Ref.: 17).
TYPE: Long-range Maritime Reconnaissance and Bomber Flying Boat
ACCOMMODATION: Crew of nine
POWER PLANT: Four Mitsubishi “Kinsei 46” radial engines, rated at 930 hp each
PERFORMANCE: 211 mph at 19,685 ft
COMMENT: The Kawanishi H6K4 was an Imperial Japanese Navy flying boat used during WW II for maritime patrol duties. The IJ Navy designation was “Type 97 Large Flying Boat”, The Allied reporting name for the type was “Mavis”.
The aircraft was designed in response to a Navy requirement of 1934 for a long range flying boat and incorporated knowledge gleaned by a Kawanishi team that visited the Short Brothers factory in the UK, at that time one of the world’s leading producers of flying boats, and from building the Kawanishi H3K, a license-built, enlarged version of the Short “Rangoon”. The Type S, as Kawanishi called it, was a large, four-engine monoplane with twin tails, and a hull suspended beneath the parasol wing by a network of struts. Three prototypes were constructed, each one making gradual refinements to the machine’s handling both in the water and in the air, and finally fitting more powerful engines. The first of these flew on 14 July 1936 and was originally designated “Navy Type 97 Flying Boat”, later H6K. Eventually, 217 would be built.
H6Ks were deployed from 1938 onwards, first seeing service in the Sino-Japanese War and were in widespread use by the time the full-scale Pacific War erupted, in 1942. At that time of the war, four Kokutai (Air Groups) operated a total of 66 H6K4s.
The type had some success over South East Asia and the South Pacific. H6Ks had excellent endurance, being able to undertake 24-hour patrols, and were often used for long-range reconnaissance and bombing missions. From bases in the Dutch East Indies, they were able to undertake missions over a large portion of Australia. However, the H6K became vulnerable to a newer generation of heavier armed and faster fighters. It continued in service throughout the war, in areas where the risk of interception was low. In front-line service, it was replaced by the Kawanishi H8K “Type 2 Large-sized Flying Boat“, Allied code name “Emily” (Ref.: 24).
TYPE: Amphibious biplane reconnaissance and air-sea rescue aircraft
ACCOMMODATION: Crew of three to four
POWER PLANT: One Bristol “Pegasus VI” radial engine, rated at 680 hp
PERFORMANCE: 135 mph at 4,750 ft
COMMENT: The Supermarine “Walrus” (originally known as the Supermarine “Seagull V”) was a British single-engine amphibious biplane reconnaissance aircraft first flown in 1933. It was operated by the Fleet Air Arm (FAA) and also served with the Royal Air Force (RAF). It was the first British squadron-service aircraft to incorporate in one airframe a fully retractable main undercarriage, completely enclosed crew accommodation and all-metal fuselage.
Designed for use as a fleet spotter to be catapult launched from cruisers or battleships, the “Walrus” was later employed in a variety of other roles, most notably as a rescue aircraft for downed aircrew. It continued in service throughout WW II.
The single-step hull was constructed from aluminium alloy, with stainless-steel forgings for the catapult spools and mountings. Metal construction was used because experience had shown that wooden structures deteriorated rapidly under tropical conditions. The wings, which were slightly swept back, had stainless–steel spars and wooden ribs and were covered in fabric. The lower wings were set in the shoulder position with a stabilising float mounted under each one. The horizontal tail surfaces were positioned high on the tail fin and braced on either side by N struts. The wings could be folded on ship for stowage. The single “Pegasus” radial engine was housed at the rear of a nacelle mounted on four struts above the lower wing and braced by four shorter struts to the centre-section of the upper wing. This powered a four-bladed wooden pusher propeller. The pusher configuration had the advantages of keeping the engine and propeller further out of the way of spray when operating on water and reducing the noise level inside the aircraft. Also, the moving propeller was safely away from any crew standing on the front deck, which would be done when picking up a mooring line.
Although the aircraft typically flew with one pilot, there were positions for two. The left-hand position was the main one, with the instrument panel and a fixed seat, while the right-hand seat could be folded away to allow access to the nose gun-position via a crawl-way. Behind the cockpit, there was a small cabin with work stations for the navigator and radio operator.
A total of 740 Walruses were built in three major variants: the “Seagull V”, “Walrus I”, and the “Walrus II”. The Mark IIs were all constructed by Saunders-Roe and the prototype first flew in May 1940. This aircraft had a wooden hull, which was heavier but had the advantage of using less of the precious wartime stockpiles of light metal alloys. Saunders-Roe would go on to build under license 270 metal Mark Is and 191 wooden-hulled Mark IIs.
The successor to the “Walrus” was the Supermarine “Sea Otter” – a similar but more powerful design. “Sea Otters” never completely replaced the “Walruses”, and served alongside them in the air-sea rescue role during the latter part of the war.
The “Walrus” was known as the “Shagbat” or sometimes “Steam-pigeon”; the latter name coming from the steam produced by water striking the hot “Pegasus” engine.
The main task of ship-based aircraft was patrolling for Axis submarines and surface-raiders, and by March 1941, “Walruses” were being deployed with Air to Surface Vessel (ASV) radars to assist in this.
By 1943, catapult-launched aircraft on cruisers and battleships were being phased out; their role at sea was taken over by much-improved radar. Also, a hangar and catapult occupied a considerable amount of valuable space on a warship. However, “Walruses” continued to fly from Royal Navy carriers for air-sea rescue and general communications tasks. Their low landing speed meant they could make a carrier landing despite having no flaps or tailhook (Ref.: 24).
TYPE: Anti-ship and -fortification explosive filled glide bomb as “Mistel” composition. Project
ACCOMMODATION: Pilot only in Arado Ar 234C-3
POWER PLANT: None with glide bomb, two BMW 003A turbojet engines with Arado Ar 234C-2, rated at 850 kp each
PERFORMANCE: Data not available
COMMENT: This “Mistel 5” project was one of the last glide bomb developments submitted to the RLM before the end of WW II. Arado, working with Rheinmetall-Borsig, designed a simple glide bomb that would be powered (version B) or unpowered (version A) and carried beneath the Arado 234 “Blitz” bomber or Heinkel He 162 “Spatz” interceptor. The purpose of this glide bomb, which could be guided by radio control or a target guidance system, was to attack targets such as ships or military facilities.
construction of the Arado Ar E.377 was wooden throughout the entire aircraft. The fuselage was circular in cross section and was cigar shaped. The nose held 2,000 kg of high explosive especially suitable for ship attacks. In addition 500 kg of an incendiary liquid was stored in the rear fuselage which also acted as ballast to counterbalance the forward warhead. The wings were tapered and shoulder mounted. They also served as auxiliary fuel tanks for the guide aircraft. A cruciform tail unit was mounted at the rear of the fuselage. For take-off the “Mistel 5” composition was set on a releasable trolley, developed by Rheinmetal-Borsig.
Upon arrival of the target the E.377 glide bomb was released by means of explosive bolts and flew to the target by means of a radio-control (Ref.:17).
COMMENT: The Yokosuka MXY8 “Akigusa” (“Autumn grass”) was a training glider built in parallel with the Mitsubishi J8M rocket-powered interceptor aircraft.
The J8M was to have simply been a licence-built Messerschmitt Me 163 “Komet” (“Comet”), but due to difficulties in obtaining technical materials from Germany, it eventually had to be designed almost from scratch. The MXY8 was designed in parallel with the J8M to validate the design, and then to provide pilot training during the development of the actual interceptor. The Imperial Japanese Army Airforce designation for the trainer was Mitsubishi Ku-13
The MXY8 was built entirely of wood, and fitted with ballast tanks that would be filled with water to simulate the weight and therefore flight characteristics of a fully equipped J8M. Some 50-60 of these gliders were eventually built.
A more advanced trainer, the MXY9, equipped with a primitive turbojet engine was planned, but was never produced (Ref.: 24).
POWER PLANT: One Ranger XV-770-8-8 inline air-cooled engine, rated at 600 hp
PERFORMANCE: 172 mph at 8,100 ft
COMMENT: The Curtiss SO3C “Seamew” was developed by the Curtiss-Wright Corporation as a replacement for the Curtiss SOC “Seagull” as the US Navy’s’s standard floatplane scout. Curtiss named the SO3C the “Seamew” but in 1941 the US Navy began calling it by the name “Seagull”, the same name as the aircraft it replaced (the Curtiss SOC a biplane type), causing some confusion. The British Royal Navy kept the Curtiss name “Seamew” for the SO3C that they ordered. One of the US Navy’s main design requirements was that the SOC “Seagull’s” replacement had to be able to operate both from ocean vessels with a single center float and from land bases with the float replaced by a wheeled landing gear.
From the time it entered service the SO3C suffered two serious flaws: inflight stability problems and problems with the unique Ranger air-cooled, inverted V-shaped inline engine. The stability problem was mostly resolved with the introduction of upturned wingtips and a larger rear tail surface that extended over the rear observer’s cockpit. The additional tail surface was attached to the rear observer’s sliding canopy and pilots claimed there were still stability problems when the canopy was open. The canopy was often open because the aircraft’s main role was spotting. While the inflight stability problem was eventually addressed (although not fully solved), the Ranger XV-770 engine proved a dismal failure even after many attempted modifications. Poor flight performance and a poor maintenance record led to the SO3C being withdrawn from US Navy first line units by 1944. The older biplane Curtiss SOC “Seagull” was taken from stateside training units and restored to first-line service on many US Navy warships until the end of World War II. In total 795 Curtiss SO3C “Seamew’s”have been built (Ref.: 24).
POWER PLANT: One Walter HWK 509C liquid-fuel rocket engine, rated at 2,400 kp thrust (main chamber: 2,000 kp thrust, auxiliary chamber 400 kp thrust)
PERFORMANCE: 569 mph (estimated)
COMMENT: In 1944 the Arado design team proposed two liquid-rocket engines powered reconnaissance versions of the Arado Ar 234 “Blitz” (Lightning) high-speed bomber. The Arado Ar 234R, as it was designated, would consist of a regular Ar 234C frame but without turbojet engines. Instead two pods were installed under the wing, each containing a Walter HWK 109-509A bi-fuel rocket engine (project Ar 234R-1A). The second project Ar 234R-1B was to be powered by a Walter HWK 109-509C two chamber liquid-fuel rocket engine mounted in the rear section. Therefore a cowling would have been installed in the rear fuselage underneath the rudder. The upper rocket engine called “Steigofen” (Accelerate chamber) delivered 2,000 kp and was to be used for climbing to altitude while the lower rocket engine, “Marschofen” (Cruising chamber) delivered 400 kp thrust and was used to power the aircraft during horizontal flight. During return flight – over a distance of more than 155 miles – the aircraft flew as a glider without power. The wing had a laminar profile with its maximal thickness at 50 to 60% chord. The glide ratio was calculated to 1:14.
Because of the limited fuel capacity and short endurance of the rocket engines the Ar 234R-1b was to be towed by a Heinkel He 177 “Greif” heavy bomber. A possible reconnaissance mission in the London area was calculated as follows: After take-off from a Luftwaffe base near Paris the aircraft was towed to the operational altitude of app. 26,247 ft, reached near Calais. After release of towline with “Steigofen” at full throttle the aircraft was powered at a speed of app. 506 mph to an altitude of app. 55,775 ft. This height was reached in a few minutes app. near the coast of Dover. During horizontal flight intermittent ignition of the “Marschofen” accelerated the aircraft with 569 mph to the target (i. e. London). After photo mission the aircraft flew back to the coast of England at a speed of 541mph and the descent back to the home base was flown as a glider. The mission was estimated for 21 minutes.
Although the Arado Ar 234R-1B project was promising it was abandoned in favor of the DFS 228 reconnaissance rocket-driven glider giving even better ceiling of 75,460 ft (Ref: 16).
POWER PLANT: One Nakajima NK9H “Homare” 42 radial engine, rated at 2,000 hp
PERFORMANCE: 426 mph at 32,810 ft
COMMENT: The Kawanishi J6K1 “Jinpu”was a purpose-built land based interceptor designed for the Imperial Japanese Navy Air Force, but that didn’t enter production because of the success of the same company’s Kawanishi N1K2-J “Shiden” (“Violet lightning”, Allied code “George”).
The J6K1 was developed from the Kawanishi J3K1 of 1942. This was to have been powered by the Mitsubishi MK9A radial engine, and would have been a fairly standard looking radial engined fighter, but it didn’t progress beyond the early design stage.
Work on the J6K1 began in 1943. This time the aircraft was to use the Nakajima “Homare” 42 engine, the design progressed far enough to receive a popular name, the “Jinpu”(Squall). The new interceptor would have been very heavily armed, with two 30mm cannon and two 13.2mm machine guns, and with a good top speed of 426mph. The J6K1 never entered production. Kawanishi had also produced the N1K1 Kyofu” (“Mighty wind, Allied code “Rex”) float plane fighter, which was followed by a normal landed based version, the Kawanishi N1K1 “Shiden”. This was then superseded by the N1K2-J “Shiden-Kai”, a smaller aircraft than the J6K, armed with four 20mm cannon and with sufficiently impressive performance to meet the Navy’s requirements. The N1K2-J was produced in large numbers, while the J6K1 was cancelled (Ref.: 24).
POWER PLANT: One Pratt & Whitney R-2800-34W “Double Wasp” radial engine, rated at 2,300 hp
PERFORMANCE: 421 mph at 19,700 ft
COMMENT: The Grumman F8F “Bearcat” concept began during a meeting between Battle of Midway veteran Grumman F4F “Wildcat” pilots and Grumman authorities on June 1942. At the meeting, Lieutenant Commander J. Thatch emphasized one of the most important requirements in a good fighter plane was “climb rate”.
Climb performance is strongly related to the power-to weight ratio, and is maximized by wrapping the smallest and lightest possible airframe around the most powerful available engine. Another goal was that the new fighter – Grumman’s design designation for the aircraft was G-58 – should be able to operate from escort carries, which were then limited to the obsolescent F4F “Wildcat” as the Grumman F6F “Hellcat” was too large and heavy. A small, lightweight aircraft would make this possible. After intensively analyzing carrier warfare in the Pacific Theatre of Operation for a year and a half, Grumman began development of the G-58 “Bearcat” in late 1943.
In 1943, Grumman was in the process of introducing the F6F Hellcat, powered by the Pratt & Whitney R-2800 engine which provided 2,000 horsepower. The R-2800 was the most powerful American engine available at that time, so it would be retained for the G-58. This meant that improved performance would have to come from a lighter airframe.
To meet this goal, the Bearcat’s fuselage was about 1.5 m shorter than the Hellcat, and was cut down vertically behind the cockpit area. This allowed the use of a bubble canopy, the first to be fit to a US Navy fighter. The vertical stabilizer was the same height as the Hellcat’s, but increased aspect ratio, giving it a thinner look. Similarly, the main wing had the same span, but having lower thickness, especially at the root. Structurally the fuselage was strengthened and armor protection was provided for the pilot, engine and oil cooler. Compared to the “Hellcat”, the “Bearcat” was 20% lighter, had a 30% better rate of climb and was 50 mph (80 km/h) faster.
The Navy placed a production contract for 2,023 aircraft based on the second prototype on 6 October 1944. On February 1945 they awarded another contract for 1,876 slightly modified aircraft from General Motors, given the designation F3M-1. These differed primarily in having the R-2800-34W engine and a small increase in fuel capacity.
Deliveries from Grumman began on May 1945. The end of the war led to the Grumman order being reduced to 770 examples, and the GM contract being cancelled outright. An additional order was placed for 126 F8F-1B’s replacing the .50 cal machine guns with the 20 mm M2 cannon, the US version of the widely used Hispano-Suiza HS.404. The F8F prototypes were ordered in November 1943 and first flew on 21 August 1944, a mere nine months later. The first production aircraft was delivered in February 1945 and the first squadron, VF-19, embarked to CV 16 “Lexington”, was operational by May 1945, but WW II was over before the aircraft saw combat service (Ref.: 24).