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).
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).
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).
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).
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).
POWER PLANT: Two Daimler-Benz DB 603A liquid-cooled engines, rated at 1,725 hp each
PERFORMANCE: 475 mph
COMMENT: The Dornier Do 335 “Pfeil” (“Arrow”) was a WW II heavy fighter built by the Dornier Company. It’s performance was much better than any other twin-engine designs due to its unique push-pull configuration and the lower aerodynamic drag of the in-line alignment of the two engines. It was Luftwaffe’s fastest piston-engine aircraft of World War II. The Luftwaffe was desperate to get the design into operational use, but delays in engine deliveries meant that only a handful were delivered before the war ended.
The origins of the Dornier Do 335 trace back to WW I when Claude Dornier designed a number of flying boats featuring remotely driven propellers and later, due to problems with the drive shafts, tandem engines. Tandem engines were used on most of the multi-engine Dornier flying boats that followed, including the highly successful Dornier Do J “Wal” (“Whale”) and the gigantic Donier Do X. The remote propeller drive, intended to eliminate parasitic drag from the engine entirely, was tried in the innovative but unsuccessful Dornier Do 14, and elongated, tubular drive shafts as later used in the Do 335 saw use in the rear engines of the four-engine, twinned tandem-layout Dornier Do 26 flying boat.
There are many advantages to this design over the more traditional system of placing one engine on each wing, the most important being power from two engines with the frontal area (and thus drag) of a single-engine design, allowing for higher performance. It also keeps the weight of the twin power plants near, or on, the aircraft centerline, increasing the roll rate compared to a traditional twin. In addition, a single engine failure does not lead to asymmetric thrust, and in normal flight there is no net torque, so the plane is easy to handle. The choice of a full “four-surface” set of cruciformly tail surfaces in the Do 335’s rear fuselage design, included a ventral vertical fin-rudder assembly to project downwards from the extreme rear of the fuselage, in order to protect the rear propeller from an accidental ground strike on takeoff. The presence of the rear pusher propeller also mandated the provision for an ejection seat for safe escape from a damaged aircraft, and designing the rear propeller and dorsal fin mounts to use explosive bolts to jettison them before an ejection was attempted — as well as twin canopy jettison levers, one per side located to either side of the forward cockpit interior just below the sills of the five-panel windscreen’s sides, to jettison the canopy from atop the cockpit before ejection.
In 1939, Dornier was busy working on the P.59 high-speed bomber project, which featured the tandem engine layout. In 1940, he commissioned a flying test bed, closely modeled on the airframe of the early versions of the twin engine Dornier Do 17 bomber but only 40% of the size of the larger bomber, with no aerodynamic bodies of any sort on the wing panels and fitted with a retractable tricycle landing gear to validate his concept for turning the rear pusher propeller with an engine located far away from it and using a long tubular driveshaft. This aircraft, the Göppingen Gö 9, built by , Schrempp-Hirth, a small sailplane company, showed no unforeseen difficulties with this arrangement, but work on the Dornier P.59 was stopped in early 1940 when the RLM ordered the cancellation of all projects that would not be completed within a year or so.
In May 1942, Dornier submitted an updated version his design as the Dornier P.231, in response to a requirement for a single seat, “Schnellbomber” -like high-speed bomber/intruder. P.231 was selected as the winner after beating rival designs from Arado, Blohm & Voss and Junkers, development contract was awarded as the Dornier Do 335. In autumn 1942, Dornier was told that the Do 335 was no longer required as a “Schnellbomber”, and instead a multi-role fighter based on the same general layout would be accepted. This delayed the prototype delivery as it was modified for the new role.
The Dornier Do 335 V1 first prototype flew in October 1943 and initial trials revealed essentially good handling characteristics. Acceleration was particularly favourable and the turning circle was rather better than had been anticipated. The use of a nose-mount annular radiator for the forward engine (much like a Junkers Jumo 211-powered Junkers Ju 88, or Jumo 213-powered Focke-Wulf Fw 190D-9) and a ventral-fuselage mount air-scooped radiator installation for cooling the rear engine (appearing like that on a North American P-51 “Mustang”) was distinctive.
However, several problems during the initial flight of the Do 335 would continue to plague the aircraft through most of its short history. Issues were found with the weak landing gear and with the main gear’s wheel well doors, resulting in them being removed for the remainder of the V1’s test flights. The Do 335 V1 made 27 flights, flown by three different pilots.
During these test flights the second Do 335 V2 was completed and made its first flight on December 1943, followed by the third Do 335 V3 on January 1944. In mid January 1944, RLM ordered five more prototypes, one to be built as Do 335A-6 night fighter. By this time, more than 60 hours of flight time had been put on the Do 335 and reports showed it to be good handling characteristics, but more importantly, it was a very fast aircraft. Even with one engine out, it reached about 350 mph.
Thus the Do 335 was scheduled to begin mass construction, with the initial order of 120 preproduction aircraft to be manufactured by DWF (Dornier-Werke Friedrichshafen) to be completed no later than March 1946. This number included a number of bombers, destroyers (heavy fighters), and several yet to be developed variants. At the same time, DWM (Dornier-Werke München) was scheduled to build over 2000 Do 335s in various models, due for delivery in March 1946 as well.
On 23 May 1944, as part of the developing “Jägernotprogramm” (“Emergency Fighter Program”) directive, maximum priority was given to Do 335 production. Furthermore, the decision was made, along with the rapid shut-down of many other military aircraft development programs, to cancel the Heinkel He 219 night fighter, which also used the DB 603 engines, and use its production facilities for the Do 335 as well. However, Ernst Heinkel managed to delay, and eventually ignore, its implementation, continuing to produce examples of the He 219A.
At least 16 prototype Do 335s were known to have flown as well as Muster-series prototypes on a number of DB603 engine subtypes. The first preproduction Do 335A-0s were delivered in July 1944 to the “Erprobungskommando 335” (“Proving detachment 335”) formed for service evaluation purposes. Approximately 22 preproduction aircraft were thought to have been completed and flown before the end of WW II including approximately 11 Do 335A-1 single-seat fighters of which two examples had been converted to a trainer version Do 335A-12 for training purposes (Ref.: 7., 24).
TYPE: Long-range Maritime Reconnaissance and Bomber Flying Boat
ACCOMMODATION: Crew of ten
POWER PLANT: Four Mitsubishi MK4Q “Kasei 22” radial engines, rated at 1,380 hp each
PERFORMANCE: 290 mph at 16,400 ft
COMMENT: The Kawanishi H8K “ Type 2 Large-sized Flying Boat) was an Imperial Japanese Navy flying boat used during WW II for maritime patrol duties. The Allied reporting name for the type was “Emily”.
At the same time the type’s predecessor, the Kawanishi H6K, was going into service in 1938 the Navy ordered the development of a larger, longer-ranged patrol aircraft under the designation “Navy Experimental 13-Shi Large-size Flying Boat”. The result was a large, shoulder-winged design that is widely regarded as the best flying boat of the war. Despite this, initial development was troublesome, with the prototype displaying terrible handling on the water. Deepening of the hull, redesigning of the planing bottom and the addition of spray strips under the nose rectified this. Two further prototypes— actually pre-production aircraft— joined the development program in December 1941. The IJNAF accepted the first production version as the H8K1, “Navy Type 2 Flying Boat, Model 11”, of which 14 would be built.
The H8K1 entered production in 1941 and first saw operational use on the night of 4 March 1942 in a second raid on Pearl Harbor. Since the target lay out of range for the flying boats, this audacious plan involved a refueling by submarine, some 900 km north-west of Hawaii. Two planes from the Yokohama Kokutai (Naval Air Corps) attempted to bomb Pearl Harbor, but, due to poor visibility, did not accomplish any significant damage.
Six days after the second Pearl Harbor raid one of the “Emily’s” was sent on a daylight photo-reconnaissance mission of Midway Atoll. It was intercepted by radar directed Brewster F2A-3 “Buffalo” fighters of Marine Corps squadron VMF-221 and shot down.
After serving as an engine test bed for the Kasei 22 powered H8K2, the original H8K1 experimental aircraft was again modified as the prototype for a transport version of the H8K series. The deep hull made possible the installation of two decks, the lower deck extending from the nose to the rear hull step and the upper extending from the wing centre-section to the rear of the hull. Accommodation was provided for either twenty-nine passengers or sixty-four troops, the armament was reduced to one flexible 13mm Type 2 machine gun in the nose turret and one 20 mm Type 99 Model 1 cannon in the tail turret. A total of thirty-six H8K-2L transport flying boat “Seiku” (“Clear sky) were built between 1943 and 1945 and exclusively operated by Naval transport units.
An improved version of Kawanishi H8K2 “Type 2 Flying Boat, Model 12” (Nishiki Hikōtei 12-gata) soon appeared, and it’s extremely heavy defensive armament earned it deep respect among Allied aircrews. The H8K2 was an upgrade over the H8K-1, having more powerful engines, slightly revised armament, and an increase in fuel capacity. They were used on a wide range of patrol, reconnaissance, bombing, and transport missions throughout the Pacific war. In mid 1943, many aircraft were equipped with Mark IV Model 1 ASV radar. This was to be the definitive variant, with 112 aircraft produced.
Even though far fewer Kawanishi H8Ks were built than contemporary British Short “Sunderlands” or American Consolidated PBY “Catalinas”, the Japanese flying-boat emerged from conflict as the most outstanding water-based combat aircraft of the second World War (Ref.: 1, 24).
POWER PLANT: Two Pratt & Whitney R-2800 radial engines, rated at 2,100 hp each
PERFORMANCE: 205 mph
COMMENT: The Martin PBM-5 “Mariner” was an American patrol bomber flying boat of WW II. It was designed to complement the Consolidated PBY “Catalina” in service with the US Navy.
Designed in 1937, the Model 162 continued the rivalry which had sprung up between Martin and Consolidated by challenging the latter company’s PBY “Catalina”. A somewhat later design than the PBY, the Martin 162 was in due course to demonstrate a marked superiority of performance, an although it served in smaller quantities than the PBY during WW II, it continued to give important service for many years after 1945.
The Model 162 design featured a deep hull with a gull wing and two Wright “Cyclone” engines. To test the handling qualities of the design, Martin built a single-seat, quarter-scale model known as the Model 162A, an on June 1937, the US Navy places a contract for a single full-scale prototype, to be designated XPBM-1. First flown on February 1939, the XPBM-1 had 1,600 hp Wright R-2600-6 engines an provision for nose and dorsal turrets plus additional gun positions at the waist and tail position. The XPBM-1 was designed to carry 2,000 lb bombs or depth-charges. It had retractable stabilizing floats under the wing and a flat tailplane with outrigged fins. Later, dihedral was added to the tailplane, canting the fins inward to give the Martin flying boat one of its most striking characteristics. At the end of 1937 the Navy ordered 20 production model PBM-1s, for which the name “Mariner” was eventually chosen. All aircraft were completed by April 1941 and went into service during 1941.
On November 1941, orders were placed with Martin for 379 PBM-3 “Mariners” and these appeared, from 1942 onwards, in several different versions. All “Mariners” from the -3 model onward had fixed, strut-braced wing floats and lengthened engine nacelles, the latter providing stowage for bombs or depth-charges. The basic PBM-3 had Wright R-2600-12 engines, and variants includes 50 unarmed PBM-3R transports with seats for 20 passengers, 274 PBM3Cs with standardized US/British equipment and 201 PBM-3Dswith Wright R-2600-22 engines and improved armament and armor protection. Many of the PBM-3Cs and -3Ds carried search radar in a large housing above and behind the cockpit, and experience with the use of this radar led to development in 1944 of a long-range anti-submarine version, the Martin PBM-3S. A total of 156 of the latter variant were delivered, with R-2600-12 engines.
In 1943, the Martin XPBM-5 appeared with 2,100 Pratt & Whitney R-2800-22 or -34 engines, and production contracts were placed for this variant in January 1944. The PBM-5, delivered from August 1944 to the end of the war, had eight 0.50-in machine guns and AN/APS-15 radar. They were used as long-range reconnaissance aircraft and for the anti-submarine role. Production totaled 631 aircraft (Ref.: 23).
POWER PLANT: Two Daimler-Benz DB 603A liquid-cooled piston engines, rated at 1,750 hp each
PERFORMANCE: 348 mph at 19,685 ft
COMMENT: When the “Führungsstab der Luftwaffe” (Operations Staff of the Luftwaffe) drafted its so-called “Bomber B” requirement which was translated into a specification for issue to selected airframe manufactures in July 1939 by the “Technischen Amt des Reichluftfahrtministeriums” (RLM), (Technical Office of the RLM), its intention was nor merely the provision of successors for the Junkers Ju 88 and Heinkel He 111; its aim was also to carry the state of the art in medium bomber design a significant step forward.
The specification was noteworthy in the performance advances that it stipulated, and equally so in design innovations that it called for. The “Bomber B” had to possess a range of 2,237 miles do endow it with a radius of action sufficient to encompass the entire British Isles from bases that it was assumed would be available in France and Norway, a maximum speed of 373 mph at 19,685-22,965 ft., which compared favourably with the speeds of the best contemporary fighters, and a bomb load of 4,410 lb. It had to carry three or four crew members, possess a loaded weight of the order of 44,090 lb., and be of twin-engined configuration, utilizing the extremely advanced 24-cylinder liquid-cooled Daimler-Benz DB 604 or Junkers Jumo 222 engines then at an early stage in development, but the really radical demands of the specification were its insistence on pressurized accommodation for the crew, and the use of remotely-controlled barbettes to house defensive armament.
Initially, the specification was issued to four manufacturers: Arado, Dornier, Focke-Wulf and Junkers, although the scope of the contest was later to be broadened to include Henschel (Henschel Hs 130) when it was realized by the RLM that this company has more pressure cabin experience than any other contestants, with the possible exception of Junkers. The final proposals of the original four competing companies were submitted to the “Technisches Amt” in July 1940, and evaluation eliminated the Arado contender, the Ar 340, prototypes being ordered of each of the other contender, Dornier Do 317, Focke-Wulf Fw 191 and Junkers Ju 288.
Dornier’s proposal was based broadly on the design of the Dornier Do 217, the four crew members being housed ahead of the wing in a pressure cabin which, taking the form of a detachable compartment pressurized by tapping the superchargers of the Daimler-Benz DB 604 engines, was extensively glazed by a series of curved panels.
Two versions of the Do 317 were proposed: the simplified Do 317A, powered by two DB 603A engines (instead of the troublesome Daimler-Benz DB 604) and featuring conventional defensive armament, and the more advanced Do 317B with the heavy 1.5 tonnes apiece, counter-rotating DB 610A/B “power system” engines, remotely aimed “Fernbedienbare Drehlafette” (FDL)-style gun turrets (remotely-controlled turrets), heavier bombload, and an extended wing.
Six prototypes of the Dornier Do 317A were ordered, and the first of these, the Do 317 V1, commenced its flight test program on September 1943. The Do 317 V1 was very similar in appearance to the later Dornier Do 217K and -M subtypes, with a visually reframed slight variation of its multiple glazed-panel “stepless cockpit”, fully glazed nose design that accommodated a pressurized cabin provision, and triangular tailfins. Trials with the Do 317 V1 revealed no real performance advance over the Do 217. However, it was clear even at this point that the call for designs was to some extent a formality, as the Junkers Ju 288 design had already been selected for production. So it was decided to complete the remaining five prototypes without cabin pressurization equipment and fit them out with FuG 230 “Kehl-Straßburg” radio guidance transmitting gear to employ them as Henschel Hs 293 missile launchers. In this form, the prototypes were redesignated Dornier Do 217R. At this time, the Do 317B project was abandoned due to changing wartime conditions (Ref.: 7, 24).
ACCOMMODATION: Crew of two plus eight passengers or equivalent cargo
POWER PLANT: Two Hitachi Ha-13a radial engines, rated at 510 hp each
PERFORMANCE: 233 mph
COMMENT: The Tachikawa Ki-54 was a Japanese twin-engine advanced trainer and light transport aircraft used during WW II. The aircraft was developed in response to an Imperial Japanese Army Air Force requirement for a twin-engine multi-purpose trainer, principally for crew training. The prototype first flew in summer 1940 and, on completing trials, entered production in 1941 as “Army Type 1 Advanced Trainer Model A” (Tachikawa Ki-54a). The Ki-54a was soon followed by the Tachikawa Ki-54b as “Army Type 1 Operations Trainer Model B” and Tachikawa Ki-54c as “Army Type 1 Transport Model C”.
The Tachikawa Ki-54c was a light transport and communication version characterized by its smooth upper fuselage line and was fitted with eight seats. A similar version was built in small numbers as Tachikawa Y-59 for civil operators. Late in the war an all-wood version of the Ki-54c, the Tachikawa Ki-110 was built, but the aircraft was destroyed during an American air raid.
As a crew trainer and light transport, the Tachikawa Ki-54 was one of the most successful Japanese aircraft of the war and was well known to the Allies which named it “Hickory” regardless of the version. The code name “Joyce” was erroneously assigned to a non-existent light bomber version.
A total of 1,368 Ki-54 were built by Tachikawa Hikoki K.K. during the war. A few captured aircraft were flown after the war by various users (Ref.: 1, 24).
Scale 1:72 aircraft models of World War II
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