All posts by Gunther Arnold

Heavy Bomber

Boeing B-17F “Flying Fortress, 303 BG “Hell’s Angels”, 8th USAAF (Hasegawa)

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TYPE: Heavy bomber

ACCOMMODATION: Crew of ten


POWER PLANT: Four Wright R-1820-97 Cyclone supercharged radial engines, rated at 1,200 hp each

PERFORMANCE: 287 mph

COMMENT: The Boeing B-17 “Flying Fortress” was a four-engine heavy bomber developed in the 1930s for the United States Army Air Corps (USAAC). Competing against Douglas and Martin for a contract to build 200 bombers, the Boeing entry (prototype Model 299, XB-17) outperformed both competitors and exceeded the air corps’ performance specifications. Although Boeing lost the contract (to the Douglas B-18 “Bolo”) because the prototype crashed, the air corps ordered 13 more B-17s for further evaluation. From its introduction in 1938, the B-17 “Flying Fortress” evolved through numerous design advances becoming the third-most produced bomber of all time, behind the American four-engined Consolidated B-24 “Liberator” and the German multirole, twin-engined Junkers Ju 88.
On 8 August 1934, the USAAC tendered a proposal for a multiengine bomber to replace the Martin B-10. The Air Corps was looking for a bomber capable of reinforcing the air forces in Hawaii, Panama, and Alaska. Requirements were for it to carry a “useful bombload” at an altitude of 10,000 ft, a range of 2,000 mi and a top speed of at least 250 mph was desired.
The prototype XB-17, with the Boeing factory designation of Model 299, was built at Boeing’s own expense. It combined features of the company’s experimental XB-15 bomber and Model 247 transport. The first flight of the Model 299 was on  July 1935 and on 20 August 1935, the prototype flew from Seattle to Wright Field in nine hours and three minutes with an average cruising speed of 252 miles per hour, much faster than the competition.
The USAAC had been impressed by the prototype’s performance, and on January 1936, through a legal loophole, the air corps ordered 13 YB-17s (designated Y1B-17 after November 1936 to denote its special F-1 funding) for service testing.
The YB-17 incorporated a number of significant changes from the Model 299, including more powerful Wright R-1820-39 Cyclone engines. Although the prototype was company-owned and never received a military serial (the B-17 designation itself did not appear officially until January 1936, nearly three months after the prototype crashed), the term “XB-17” was retroactively applied to the airframe and has entered the lexicon to describe the first “Flying Fortress”.
Opposition to the air corps’ ambitions for the acquisition of more B-17s faded, and in late 1937, 10 more aircraft designated B-17B were ordered to equip two bombardment groups, one on each U.S. coast. Improved with larger flaps and rudder and a well-framed, 10-panel plexiglas nose, the B-17Bs were delivered in five small batches between July 1939 and March 1940. In July 1940, an order for 512 B-17s was issued, but at the time of the attack on Pearl Harbor, fewer than 200 were in service with the army.
The aircraft went through several alterations in each of its design stages and variants. Of the 13 YB-17s ordered for service testing, 12 were used by the 2nd Bomb Group of Langley Field, Virginia, to develop heavy bombing techniques, and the 13th was used for flight testing at the Material Division at Wright Field, Ohio. Experiments on this aircraft led to the use of a quartet of General Electric turbo-superchargers which would become standard on the B-17 line
As the production line developed, Boeing engineers continued to improve upon the basic design. To enhance performance at slower speeds, the B-17B was altered to include larger rudders and flaps. The B-17C changed from three bulged, oval-shaped machine gun blisters to two flush, oval-shaped machine gun window openings, and on the lower fuselage, a single “bathtub” machine gun gondola housing, which resembled the similarly configured and located ventral defensive emplacement on the German Heinkel He 111P-series medium bomber.
While models A through D of the B-17 were designed defensively, the large-tailed B-17E was the first model primarily focused on offensive warfare. The B-17E was an extensive revision of the Model 299 design: The fuselage was extended by 10 ft; a much larger rear fuselage, vertical tailfin, rudder, and horizontal stabilizer were added to the design; a gunner’s position was added in the new tail; the nose (especially the bombardier’s well-framed, 10-panel nose glazing) remained relatively the same as the earlier B through D versions had, but with the addition of a Sperry electrically powered manned dorsal gun turret just behind the cockpit, and the similarly powered Sperry-built manned ventral ball turret just aft of the bomb bay. The B-17’s turbocharged Wright R-1820 Cyclone 9 engines were upgraded to increasingly more powerful versions of the same power plants multiple times throughout its production, and similarly, the number of machine gun emplacement locations was increased to enhance the aircraft’s combat effectiveness.
In April 1942, the B-17F was introduced onto the production lines, and outwardly this variant differed from the B-17E only in having an extended Plexiglas nose which was frameless except for the optically flat bomb-aiming panel, paddle-blade airscrews for maximum operating performance, extra fuel cells, improvements of the bomb stowage, brake system, communications equipment and oxygen system. As the cross weight was increased, the undercarriage was strengthened.
Owing to the constant modifications being applied to aircraft on the production lines and the immense scale of production orders, a system of “Block Designations” was instituted.  Thus, the first Boeing-built B-17F Fortress became B-17F-1-BO, and all aircraft in this production block were identical insofar as equipment and installations were concerned. Blocks B-17F-5-BO, -10-BO, etc., followed, the intervening number being left to indicate subsequent changes made at modification centres. Production of the B-17F continued for 15 months, during which 2,300 were built by Boeing, 600 by Douglas (suffix DL) and 500 by Locked Vega (suffix VE). The final production blocks of the B-17F from Douglas’ plants did, however, adopt the Bendix “chin turret” with two machine guns, giving them a much-improved forward defense capability.
The B-17F variants were the primary versions flying for the Eighth Air Force to face the Germans in 1943. The maximum bomb load of the first B-17F was 4.350 kg, but on typical missions to Germany, Eighth Air Force Fortresses carried 1.800- 2.270 kg over operating ranges averaging 1,400 miles. Beyond these distances, the bomb load fell rapidly, so that the effective combat radius of B-17F was about a maximum of 800 miles. Later modifications already referred to increase the fuel capacity as well as bomb load and by that the USAAF was enabled to build up an immense striking force in the European Theatre of Operations (Ref.: 4, 24).

Fighterbomber, Medium Bomber

Arado Ar 234B-2 “Blitz” (“Lightning”), (9/KG 76), (Dragon)

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TYPE: Fast medium bomber

ACCOMMODATION: Pilot only

POWER PLANT: Two Junkers Jumo 004B-1 turbojet engines, rated at 900 kp each

PERFORMANCE: 461 mph at 20,000 ft

COMMENT: In late 1940, the Reichsluftfahrtministerium (RLM, Reich Air Ministry), offered a tender for a jet-powered high-speed reconnaissance aircraft with a range of 1,340 mi. Arado was the only company to respond, offering their E.370 project, a high-wing conventional-looking design with a Junkers Jumo 004 tubojet engine under each wing.
Arado estimated a maximum speed of 480 mph at 20,000 ft, an operating altitude of 36,000 ft and a range of 1,240 mi. The range was short of the RLM request, but they liked the design and ordered two prototypes as the Arado Ar 234. These were largely complete before the end of 1941, but the Jumo 004 engines were not ready, and would not be ready until February 1943. When they did arrive they were considered unreliable by Junkers for in-flight use and were cleared for static and taxi tests only. Flight-qualified engines were finally delivered, and the first prototype, the Ar 234 V1 made its first flight on July 1943 at Rheine Airfield.
By September 1943, four prototypes were flying and four more prototypes under construction. The sixth and eighth aircraft of the series were powered with four BMW 003 turbojet engines instead of two Jumo 004s, the sixth having four engines housed in individual nacelles and the eighth flown with two pairs of BMW 003s installed within “twinned” nacelles underneath either wing. These were the first four-engine jet aircraft to fly.
The projected weight for the aircraft was approximately 8 tonnes. To reduce the weight of the aircraft and maximize the internal fuel the eight prototype aircraft were fitted with the original arrangement of trolley-and-skid landing gear, intended for the planned operational, but never-produced Arado Ar 234A version.
Arado did not use the typical retractable landing gear. Instead, the aircraft was to take off from a jettisonable three-wheeled, tricycle gear-style trolley and land on three retractable skids, one under the central section of the fuselage, and one under each engine nacelle.
The RLM had already seen the promise of the design and in July 1943 had asked Arado to supply two prototypes of a “Schnellbomber” (“Fast bomber”) version as the Arado Ar 234B. Since the original skid-equipped Ar 234A’s fuselage design was very slender and filled with fuel tanks, there was no room for an internal bomb bay and the bombload had to be carried on external racks.
Since the cockpit was directly in front of the fuselage, the pilot had no direct view to the rear, so the guns were aimed through a periscope, derived from the type used on German World War II tanks, mounted on the cockpit roof. The Ar 234B version was modified to have fully retractable tricycle landing gear, with the mid-fuselage very slightly widened to accommodate the forward-retracting main gear units, the nose gear retracting rearwards. The first twin-Jumo 004 powered prototype Ar 234B (V 7) flew on 10 March 1944 for the first time and made history on 2 August 1944 as the first jet aircraft ever to fly a reconnaissance mission.
Production B-series aircraft  were slightly wider at mid-fuselage to house the main landing gear, with a central fuel tank present (the middle one of a trio of fuel tanks) in the mid-fuselage location forward tank, central and an aft. Under tests with maximum bombload consisting of three SC 500 bomb, the Ar 234 V9 aircraft could reach 418 mph at 16,000 ft. This was still better than any bomber the Luftwaffe had at the time, and made it the only bomber with any hope of surviving the massive Allied air forces. The normal bombload consisted of two 500 kg bombs suspended from the engines or one large 1,000 kg bomb semi-recessed in the underside of the fuselage with maximum bombload being 1,500 kg. In case the full bomb load was to be deployed on an Ar 234B for an operational sortie, fuel had to be reduced and two Walter HWK 109-500A-1 “Starthilfe” (Take-off assistance) liquid fuel jettisonable JATO rocket pods delivering 500kp thrust each were fixed under each wing.
Production lines were already being set up, and 20 Arado Ar 234B-0 pre-production aircraft were delivered by the end of June 1943. Later production was slow, as the Arado plants were given the simultaneous tasks of producing aircraft from other bombed-out factories hit during the USAAF’s “Big Week”, and the ongoing license-building and nascent phasing-out of Heinkel’s heavy He 177A bomber, even as the Arado firm was intended to be the sole subcontractor for the Heinkel He 177B (He 277) series strategic bomber, meant to start construction at Arado as early as October 1944. Meanwhile, several of the Ar 234 prototypes – including a few of the surviving six twin-engine Jumo 004-powered “trolley-and-skids” Ar 234A-series prototypes – were sent forward in the reconnaissance role. In most cases, it appears they were never even detected, cruising at about 460 mph at over 29,900 ft, with the seventh prototype achieving the first-ever wartime reconnaissance mission over the United Kingdom by a Luftwaffe-used jet aircraft.
The few 234Bs entered service in autumn and impressed their pilots. They were fairly fast and completely aerobatic. The long takeoff runs led to several accidents; a search for a solution led to improved training as well as the use of two jettisonable RATO units. The Jumo 004 engines were always the real problem; they suffered constant flameouts and required overhaul or replacement after about 10 hours of operation.
The most notable use of the Arado Ar 234 in the bomber role was the attempt to destroy the Ludendorff Bridge at Remagen. The aircraft continued to fight in a scattered fashion until Germany surrendered on 8 May 1945. Some were shot down in air combat, destroyed by flak, or “bounced” by Allied fighters during takeoff or on the landing approach, as was already happening to Messerschmitt Me 262 jet fighters. Mostly the remaining aircraft sat on the airfields awaiting fuel that never arrived.
Overall from mid-1944 until the end of the war a total of 210 aircraft were built. In February 1945, production was switched to the Arado Ar 234C variant. It was hoped that by November 1945 production would reach 500 per month. Only a few of this four engine aircraft were built before Germany finally collapsed (Ref.: 24).

Fighter, Projects

Messerschmitt Me 262 HG III/ Concept 3 (Unicraft Models, Resin)

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TYPE: High-speed test aircraft. Project

ACCOMMODATION: Pilot only

POWER PLANT: Two Heinkel-Hirth HeS 011 turbojet engines, rated at 1,300 kp thrust each

PERFORMANCE: High subsonic speed, estimated

COMMENT: In early 1941 several high speed versions of the basic Messerschmitt Me 262 were designed on the drawing board. The first of these “Hochgeschwindigkeitsjäger” (HG), (High-speed fighter) was the Messerschmitt Me 262 V9, unofficially called HG I. This aircraft featured modified wing leading edges of the inner wing section, swept angles of stabilizers, and a “Rennkabine” (Racing canopy), shallow, low-drag cockpit canopy and windscreen with low profile.
Other two projects were created following this way: The Me 262 HG II called for an outboard wing of increased chord and an improved air intake and engine installation, and finally  the Me 262 HG III, which was the final stage of development. It required more radical modifications, as a new 45 degree swept wing with engines housed in the wing roots. Three variants of the Me 262 HG III are known correspond to the original layout.
Entwurf 1” (Concept 1) had a the original tail plane of the Me 262, “Entwurf 2” (Concept 2) had a butterfly-type tail plane, and “Entwurf 3” (Concept 3) together with various subtypes was considerably altered in the fuselage area, where the cockpit was relocated at the rear and formed a part of the empennage group. The swept back stabilizers were located behind the cockpit. This Messerschmitt Me 262 HG III/ Concept 3 attained a very high state of fighter technology, which in the post-war period was the only realized abroad after a passage of several years.

Trainer

M6A1-K “Nanzan” (“South Mountain”), (‘Shisei-Seiran Kai), (MPM-Models)

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TYPE: Trainer aircraft for Aichi M6A1 “Seiran”

ACCOMMODATION: Pilot and trainer

POWER PLANT: One Aichi Atsuta Type 32 liquid-cooled engine, rated at 1,400 hp

PERFORMANCE: 310 mph at 17,060 ft

COMMENT:  The Aichi M6A1-K “Seiran Kai” was a trainer version of the submarine-launched attack floatplane Aichi M6A1 “Seiran”. It was fitted with an inwardly-retracting undercarriage, and the folding tip of the rudder was dispensed with as the absence of floats improved directional stability. The popular name of the M6A1-K was later changed to “Nanzan” (Southern Mountain”).
Two prototypes of this aircraft were built and flight tested before the war in the Pacific ended in 1945 (Ref.: 24).

Heavy Bomber, Assemblyships

Consolidated B-24D “Liberator” “Striped Ass”, 466th BG (H), 8th USAAF, (Airfix Models)

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TYPE: Heavy bomber, Assembly ship

ACCOMMODATION: Crew of four

POWER PLANT: Four Pratt & Whitney R-1830-43 Twin Wasp radial engines, rated at 1,200 hp each

PERFORMANCE: 303 mph at 25,000 ft

COMMENT: The Consolidated B-24 “Liberator was a heavy long-range bomber of the USAAF during WW II and large aircraft for its day. It had a wing span of 110 feet and a gross weight of more than 30 tons. Powered by four 1,200 hp radial engines, it had a maximum fuel capacity of 2,814 US gallons and the bomb load varied from 2,000 to 4,000 kp depending on the distance of the target to be attacked. The crew varied from eight to 10 men, five or six of whom acted as gunners, manning the 10 machine guns usually carried for defence.
The operating technique with these heavy bombers was, after take-off, to assemble large formations of from 20 to 40 aircraft while climbing to operational altitude of 20,000 to 25,000 feet. This was coordinated by means of “Assembly Ships” (or “Formation Ships”) specially fitted to aid assembly of individual group formations. They were equipped with signal lighting, provision for quantity discharge of pyrotechnics, and were painted with distinctive group-specific high-contrast patterns of stripes, checkers or polka dots to enable easy recognition by their flock of bombers. The aircraft used in most cases were veteran B-24Ds. All armament and armor was removed and arrangements for signal lighting varied from group to group, but generally consisted of white flashing lamps on both sides of the fuselage arranged to form the identification letter of the group. Such an assembly was despatched from a single airfield and joined with other formations to form a division column of perhaps 500 to 600 bombers.
The 446th Bombardment Group (H) with Component Squadrons 784th, 785th, 786th and 787th Bombardment Squadron (H) was activated on 1 Aug. 1943 at Alamogordo AAFd. NM. The training for combat commenced at Kearns Fd. Utah end Aug. 43, remaining there until Nov, 43, when the group moved back to Alamogordo AAFd, NM. In early Feb. 44 the group moved to Topeka AAFd, Kan and after a week’s stay began movement to the UK. Here the group was stationed at Attlebridge, Norfolk, for the last year of the war in Europe.
Combat aircraft were Consolidated B-24H, B-24J, B-24L and B-24M. In total the group flew 232 missions in the course of the year against strategic objectives like U-boat installations in Kiel, ball bearing works in Berlin, aircraft factories in Munich and oil refineries in Hamburg. Remarkably, the 785th Bomb Squadron flew 55 consecutive missions without loss. The aircraft shown here is the assembly ship of the 446th Bombardment Group. It’s a veteran Consolidated B-24D named “Striped Ass” (Ref: 2).

Notice: Identification markings of this aircraft are mostly hand-made. After airbrushing the surface with different aluminum-silver shading red stripes are applied according to the original. For this I used microthin precision slit tape, Bishop Graphics. Inc., Westlake Village, Ca. This is self-adhesive, in red color, extreme thin and easy to apply. Unfortunately transparent it needed to be painted stripe by stripe before being applied.

Fighter, Projects

Messerschmitt Me P. 1110/II “Tunnel-Einlauf”, (“Tunnel-air-intake”) with Kramer X-4, (Planet Models, Resin)

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TYPE: High altitude fighter

ACCOMMODATION: Pilot only

POWER PLANT: One Heinkel-Hirth HeS 011 turbojet engine, rated at 1,300 kp

PERFORMANCE: 630 mph

COMMENT: In Autumn 1944, in the context of the “Jägernotprogramm” (“Emergency Fighter Program”) the Oberkommando der Luftwaffe (OKL, Luftwaffe High Command) requested for proposals for a new generation of fighter/interceptor aircraft in order to replace the Heinkel He 162 “Salamander” or “Volksjäger” (“Peoples fighter”).
Besides designs such as Blohm & Voss Bv P.212, Focke-Wulf Ta 183, Heinkel He P. 1078, and Junkers EF 128 Messerschmitt proposed its project Me P. 1110 with three different variants.
First of the designs was the Messerschmitt Me P.1110/I, a turbo-jet powered interceptor with a conventional-looking design with the air intakes located in the middle part of fuselage sides above the wing the inlet not protruding the cross section (“Rampen-Einlauf”, “Ramp-air-intake”). The wing was of wooden construction and was swept back to 60 degree at the wing root and 40 degree at the leading edge. The tail plane was conventional with elevators and a vertical fin and swept back. Power was provided by a Heinkel/Hirth HeS 011 turbojet engine. A pressurized cockpit with streamlined fairing,  tricycle landing gear and three MK 108 30mm cannon in the nose with a provision for two more in the wing roots was envisaged.
The second design was the Messerschmitt Me P.1110/II that differed from the Me P.1110/I mainly in a V-tail unit and a divided annular air intake behind the cockpit. The advantage of this unusual arrangement was that it would reduce drag by fifteen percent compared to a single nose air intake at the cost of four percent air flow reduction to the jet engines. To increase the air flow a supercharger was provided that additionally withdraw the boundary layer.
Like the Me P.1110/I, the Me P.1110/II had 40 degree swept-back wings, an HeS 011 jet engine and was armed with three MK 108 30mm cannon in the nose with a provision for two more in the wing roots.
The third design the Messerschmitt Me P.1110 “Ente” was of canard configuration with small wings in the front and larger wings in the rear part of the fuselage.
All projects would be soon dropped in favor of the Junkers EF 128 and none of the Messerschmitt designs made it to the prototype stage. (Ref.: 20, 22).

Medium Bomber, Cargo

Bristol “Buckingham” B 1 (Valom)

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TYPE: Medium bomber

ACCOMMODATION: Crew of two

POWER PLANT: Two Bristol “Centaurus” IX radial engines, rated at 2,520 hp each

PERFORMANCE: 336 mph at 12,000 ft

COMMENT : In early 1939 Bristol suggested a bomber variant of the “Beaufighter” with their Bristol “Hercules” engines. British policy at the time was an expectation for medium bombers to be provided from the US allowing British industry to concentrate on heavy bomber designs but a design was requested preferably based on an existing design which meant working with the Bristol “Beaufort” or “Beaufighter”.
Air Ministry specification B.7/40 called for a medium bomber to replace the Bristol “Blenheim”. The specification stipulated a speed of at least 300 mph at 5,000 ft, a normal load of 500 kg of bombs and a center turret armed with at least two 12.7 mm machine guns. Only Armstrong Whitworth Company tendered a full design but it did not meet with approval. So when Bristol brought their Type 162 (tentatively named “Beaumont”), which was fortunately well matched to B.7/40 specification, to the Air Staff, this led to a request to complete a mockup in 1940 and then a confirmed contract for three prototypes in February 1941. The “Beaumont” was based on the rear fuselage and tail of a “Beaufighter”, with a new center and front fuselage. The armament was a mid-upper turret with four machine guns, four more machine guns firing forward and two firing to the rear.
Construction began in late 1940, with a new Air Ministry Specification B.2/41 to be written around it. Changes in the requirements, removing dive bombing and ground attack support which incoming US bombers were expected to be capable of and increasing the performance to allow for the future, meant the “Beaumont” would no longer suffice. The changes in performance, requiring a bomb load of 4,000 lb, a speed of 360 mph and a range of 1,600 miles meant a redesign by Bristol to use the Bristol “Centaurus” engine.
The Bristol redesign with a larger wing and the more powerful engines was the Bristol ”Buckingham”. It had gun installations in the nose, dorsal and ventral turrets. Generally conventional in appearance, one unusual feature was that the bomb-aimer/navigator was housed in a mid-fuselage ventral gondola, resembling those on the earlier German Heinkel He 111H and American Boeing B-17C and -D in appearance. This was part of an attempt to give all the crew positions unobstructed views and access to each other’s positions. The bomb bay could hold up to 2,000 kg bombs. The rear of the gondola had a hydraulically powered turret with two Browning machine guns. The Bristol-designed dorsal turret carried four Brownings. A further four fixed, forward-firing Brownings were controlled by the pilot. Following more changes, specification B.2/41 was replaced by B.P/41. An order for 400, at an initial rate of 25 per month, was made with deliveries expected in March 1943. The first flight took place on 4 February 1943. During testing, the “Buckingham” exhibited poor stability which led to the enlargement of the twin fins, along with other modifications. The Bristol “Buckingham B1” was first flown 12 February 1944 with “Centarus” VI or XI engines, 400 ordered but reduced first to 300 then to 119, with only 54 built as bombers. Overtaken by events, it was mainly used primarily for transport and liaison duties (Ref.: 24).

Medium Bomber, Projects

Arado Ar. 340 (Anigrand Models, Resin)

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TYPE: Medium bomber

ACCOMMODATION: Crew of four

POWER PLANT: Two Junkers Jumo 222 or Daimler-Benz DB 604 (both liquid-cooled) or BMW 802 (radial) piston engines
PERFORMANCE: 360 mph

COMMENT: In 1939, the “Technisches Amt des Reichluftfahrtministeriums” (RLM); (Technical Office of the Reich Air Ministry) issued specification for a “Bomber B” requirement.
The Reich Air Ministry ordered the aircraft to replace the Junkers Ju 88 and Dornier Do 217 bombers by 1943. At first four manufacturers submitted plans to the Air Ministry: Arado project E.340, Dornier Do 317, Focke-Wulf Fw 191, and Junkers Ju 288. Later, Henschel was asked to submit its Henschel Hs 130 design due to the expertise of this company with its experiments with pressurized cockpits. Meanwhile, Project “Bomber B” contest winner was the Arado design, officially named Ar 340.
While the designs of all other contenders were of more conventional layout the Arado Ar 340 was designed with a central fuselage containing all four crew members. The cockpit and rear compartment were glazed and pressurized. The projected Junkers Jumo 222 engines were positioned in a unique twin-boom arrangement connected only through the wing assembly, a configuration which offered the crew better visibility. The landing gear was mounted to the load-bearing wing center-section. The tail of the aircraft was a unique design, where the tail plane did not connect the two booms but was cantilevered outwards instead, each similar to the asymmetric Blohm & Voss Bv 141B booms and tail arrangement. Also similarly, this would have provided the rear gunner with a clear range of fire directly behind. The fuselage extended forwards beyond the engines, with the gunners situated behind the cockpit, ahead of the bomb bay and wing spars. The MG 151 cannon in the tail of the central fuselage would have been controlled with remote aiming through periscopes. There were also two remote-controlled “Fernbedienbare Drehlafette FDL 131” 13mm (remotely-controlled gun turrets) to be placed above and below the fuselage.
The Ar 340 was one of the steadily growing numbers of later-war military airframe designs designed to use the troublesome Junkers Jumo 222 engine. Otherwise an innovative design, these powerful engines were selected because they would have allowed the Arado Ar 340 to carry the required payload of 5,900 kg within a relatively compact airframe, despite their still-strictly developmental nature. As the development of the Junkers Jumo 222 engines were cancelled, plans were discussed to power the Arado Ar 340 with Daimler-Benz DB 605 liquid-cooled engines or BMW 802 radial engines. Meanwhile the RLM favoured the Junkers Ju 288 and the Arado project was not pursued.
Ultimately, the entire “Bomber B project” was cancelled, primarily as a result of the failure to develop the required engines (Ref.: 24).

Fighter

Mitsubishi A7M2 “Reppū” (“Strong Gale”, “Sam”), (MPM Models)

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TYPE: Carrier-borne and land-based fighter

ACCOMMODATION: Pilot only

POWER PLANT: One Mitsubishi Ha-43 radial engine, rated at 2,200 hp

PERFORMANCE: 390 mph at 21,660 ft

COMMENT: Towards the end of 1940, the Imperial Japanese Navy asked Mitsubishi to start design on a 16-Shi carrier-based fighter, which would be the successor to the carrier-based Mitsubishi A6M “Rei-sen” (“Zeke”, Allied reporting code “Zero”). At that time, however, there were no viable high-output, compact engines to use for a new fighter. In addition, Mitsubishi’s design’s team was preoccupied with addressing early production issues with the A6M2b as well as starting development on the A6M3 and the 14-Shi interceptor which would later become the Mitsubishi J2M “Raiden” (Allied code “Jack”), a land-based interceptor built to counter high-altitude bombers). As a result, work on the “Rei-sen” successor was halted in January 1941.
In April 1942, the development of the A6M3 and the 14-Shi interceptor was complete, and the Japanese Navy once again tasked Mitsubishi with designing a new “Zero” successor to become the “Navy Experimental 17-Shi Ko (A) Type Carrier Fighter “Reppu” (“Strong Gale”, Allied reporting code “Sam”). In July 1942 the Navy issued specifications for the fighter: it had to fly faster than 397 mph above 20,000 ft, climb to 20,000 ft in less than 6 minutes, be armed with two 20 mm cannon and two 0.51 in machine guns, and retain the maneuverability of the A6M3 “Rei-sen”.
As before, one of the main hurdles was engine selection. To meet the specifications the engine would need to produce at least 2,000 hp, which narrowed choices down to Nakajima’s NK9 (Ha-45) under development (later becoming “Homare”), or Mitsubishi’s MK9 (Ha-43), which was also still being developed. Both engines were based on 14-cylinder Nakajima “Sakae” and Mitsubishi “Kinsei”, respectively) engines converted to 18-cylinder power plants. The early NK9 had less output but was already approved by the Navy for use on the Yokosuka P1Y “Ginga” (Allied code “Frances”), while the larger MK9 promised more horsepower.
With the larger, more powerful engine, wing loading became an issue. With the MK9 the engineers concluded it could fulfill the requirements; however, production of the MK9 was delayed compared to the NK9, and the Japanese Navy instructed Mitsubishi to use the NK9.
Work on the 17-Shi was further delayed by factories prioritizing Mitsubishi  A6M “Reisen” and Mitsubishi G4M (Allied code “Betty”) bomber production as well as further work on A6M variants and addressing Mitsubishi J2M “Raiden” issues. As a result, the 17-Shi, which became the A7M1, officially flew for the first time on 6 May 1944, four years after development started. The aircraft demonstrated excellent handling and maneuverability, but was underpowered as Mitsubishi engineers feared, and with a top speed similar to the A6M5 “Rei-sen”/”Zeke”. It was a disappointment, and the Navy ordered development to stop on 30 July 1944, but Mitsubishi obtained permission for development to continue using the Ha-43 engine, flying with the completed Ha-43 on 13 October 1944. The Mitsubishi A7M2 “Reppu” now achieved a top speed of 390 mph, while climb and other areas of performance surpassed the “Zero”, leading the Navy to change its mind and adopt the aircraft. The A7M2 “Reppu” was also equipped with automatic combat flaps, used earlier on the Kawanishi N1K-J “Shiden” (Allied code “George”), significantly improving maneuverability.
In June 1945, ace pilot Saburo Sakai was ordered to Nagoya to test the airplane. He declared it to be the fastest fighter he had ever seen, able to surpass anything on the air, Japanese or American. He claimed it could fly in circles, while ascending, around a Grumman F6F “Hellcat” or a North American P-51 “Mustang”, and that engineers stated it could fight at up to 39,370 ft.
When the war in the Pacific area ended a total of 10 Mitsubishi A7M “Reppu’s” were built including only one production aircraft A7M2 (Ref.: 24).

Medium Bomber, Postwar

Convair XB-46 (Anigrand Models, Resin)

Gallery

TYPE: High-speed medium bomber

ACCOMMODATION: Crew of three

POWER PLANT: Four Allison J35A-3 turbojet engines, rated at 1.815 kp each

PERFORMANCE: 439 mph at 15,000 ft

COMMENT: In 1944, the US War department was aware of aviation advances in Germany and issued a requirement for a range of designs for medium bombers weighing from 36,287 kg to more than 90,718 kg. Designs from this competition, sometimes named the “Class of ’45”, included the Convair XB-46, the Martin XB-48, and the North American XB-45 “Tornado”.
In the fall of 1945, Convair found it was competing with itself with its XB-46 turbojet bomber when the USAAF became interested in an unorthodox forward-swept wing turbojet attack design, the Convair XA-44 that the company had also been working on. With the end of WW II severely curtailing budgets, the company considered canceling the XB-46 in favor of the other project as there was insufficient funding for both. Company officials argued that it made more sense to allow them to complete the XB-46 prototype as a stripped-down testbed omitting armament and other equipment and for the USAAF to allow them to proceed with two XA-44 airframes in lieu of the other two XB-46s on contract. In June 1946, the USAAF agreed to the substitution but that project was ultimately cancelled in December 1946 before the prototypes were completed. The XB-46 would be completed with only the equipment necessary to prove its airworthiness and handling characteristics.
The Convair XB-46 was a graceful design and had a long streamlined oval torpedo-shaped fuselage, long narrow straight shoulder-mounted wings with four Chevrolet-built Allison J35-C3 axial-flow eleven stage turbojets of 1.730 kp static thrust paired in an integral nacelle under each wing. The fuselage turned out to be a problem, as it distorted under flight loads. The pilots sat in tandem in a pressurized fighter-style cockpit under a single Plexiglas teardrop canopy with the bombardier-navigator-radio operator in a transparent Plexiglas nose section.
The straight wing had an aspect ratio of 11.6, and was equipped with Fowler flaps which extended over 90 percent of the span, in four sections. The flaps extended via electrical actuators, and had very small ailerons. Each wing had five spoilers made of perforated magnesium alloy. The engine air intakes were flat oval inlets, with a duct curving downward in a flat “S” to the engines, which were mounted behind the leading edge of the wing. The unusual flight control system utilized a system of pneumatic piping to transmit the pilots control inputs and actuate various systems, rather than the more typical hydraulic, manual or electrical control lines and systems of most aircraft of the era.
Production versions were to be equipped with a pair of .50 caliber Browning M2 machine guns in a tail turret designed by Emerson Electric Company and provision was made for an APG-27 remote control optics and sighting system, but no weaponry was fitted into the prototype.. Likewise, production aircraft were intended to be built with the General Electric J47 engines with 2.345 kp static thrust rather than the J35s used on the prototype
The XB-46’s first flight occurred 2 April 1947 after a month of taxi testing, and lasted ninety minutes. The pilot praised its handling qualities. Basic flight testing took place for five months, and by September 1947 it was concluded after 127 hours aloft on 64 flights by both the Convair Company and USAAF test pilots. Stability and control were excellent but there were engineering problems with engine de-icing, the cabin air system, and vertical oscillations caused by harmonic resonance between the wing and spoilers. There was also concern regarding the ability of the three man crew to exit the aircraft in case of an emergency, since the exit plan relied on the pneumatic system to hold the main door open against the airstream.
The B-46 program was cancelled in August 1947, even before flight testing had been completed, because it was already obsolete. The North American B-45 “Tornado” already had production orders, and even it would be eclipsed by the Boeing B-47 “Stratojet’s” superior performance (Ref.: 24).