All posts by Gunther Arnold

Nightfighter

Heinkel He 219A-0 “Uhu”, (“Eagle Owl”), I./NJG 1 (Dragon)

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TYPE: Night fighter

ACCOMMODATION: Crew of two, Pilot and Radar operator/navigator

POWER PLANT: Two Daimler-Benz DB 603G liquid-cooled engines, rated at 1,900 hp each

PERFORMANCE: 416 mph at 22,965 ft

COMMENT: The Heinkel He 219 “Uhu” (“Eagle Owl”) was a night fighter that served with the German Luftwaffe in the later stages of WW II. A relatively sophisticated design, the He 219 possessed a variety of innovations, including Lichtenstein SN-2 advanced VHF-band intercept radar, also used on the Junkers Ju 88C and Messerschmitt Bf 110G night fighters. It was also the first operational military aircraft to be equipped with ejection seats and the first operational German World War II-era aircraft with tricycle landing gear. Had the He 219 been available in quantity, it might have had a significant effect on the strategic night bombing offensive of the Royal Air Force; however, only 294 of all models were built by the end of the war and these saw only limited service.
Development and production of the He 219 was protracted and tortuous, due to political rivalries between Josef Kammhuber, commander of the German night fighter forces, Ernst Heinkel, the manufacturer and Erhard Milch, responsible for aircraft construction in the Reichluftfahrtministerium (RLM – the German Aviation Ministry). The aircraft was also complicated and expensive to build; these factors further limited the number of aircraft produced.
When engineer R. Lusser returned to Heinkel from Messerschmitt, he began work on a new high-speed bomber project called Heinkel He P.1055. This was an advanced design with a pressurized cockpit, twin ejection seats (the first to be planned for use in any combat aircraft), tricycle landing gear — featuring a nose gear that rotated its main strut through 90° during retraction (quickly orienting the nose wheel into the required horizontal position for stowage within the nose, only at the very end of the retraction cycle) to fit flat within the forward fuselage and remotely controlled, side mounted FDSL 131 defensive gun turrets similar to those used by the Messerschmitt Me 210. Power was to be provided by two of the potentially troublesome, dual-crankcase Daimler-Benz DB 610 “power system” engines then under development, weighing on the order of about 1–​1⁄2 tonnes apiece, producing 2,950 hp each, delivering excellent performance with a top speed of approximately 470 mph and a 2,500 mi range with a 2,000 kg bomb load.
The RLM rejected the design in August 1940 as too complex and risky. Lusser quickly offered four versions of the fighter with various wingspans and engine choices in order to balance performance and risk. At the same time, he offered the Heinkel He P.1056, a night fighter with four 20 mm cannon in the wings and fuselage. The RLM rejected all of these on the same grounds in 1941. Heinkel was furious and fired Lusser on the spot.
About the same time as Lusser was designing the P.1055, Kammhuber had started looking for an aircraft for his rapidly growing night fighter force. Heinkel quickly re-designed the P.1055 for this role as the Heinkel He P.1060. This design was similar in layout but somewhat smaller and powered by two of the largest displacement  single-block liquid-cooled aviation engines placed in mass production in Germany, the Daimler-Benz DB 603 inverted V12 engine. As designed by Heinkel, these engines’ nacelle accommodations featured annular radiators similar to the ones on the Junkers Jumo 211-powered Junkers Ju 88A, but considerably more streamlined in appearance, and which, after later refinement to their design, were likely to have been unitized as a Heinkel-specific “Kraftei” (Power egg) engine unit-packaging design. Nearly identical-appearance nacelles, complete with matching annular radiators, were also used on the four prototypes Heinkel He 177B prototype airframes built in 1943-44, and the six ordered prototypes of Heinkel’s He 274 high-altitude strategic bombers with added turbochargers. The early DB 603 subtypes had poor altitude performance, which was a problem for Heinkel’s short-winged design, but Daimler had a new “G” subtype of the DB 603 power plant meant to produce 1,900 hp take-off power apiece under development to remedy the problem. Heinkel was sure he had a winner and sent the design off to the RLM in January 1942, while he funded the first prototype himself. The RLM again rejected the He 219, in favour of new Junkers Ju 88- and Messerschmitt Me 210-based designs.
Construction of the prototype started in February 1942 but suffered a serious setback in March, when Daimler said that the DB 603G engine would not be ready in time. Instead, they would deliver a 603A engine with a new gear ratio to the propellers, as the DB 603C with the choice of using four-blade propellers, as the similarly-powered Focke-Wulf Fw 190C high-altitude fighter prototypes were already starting to use into early 1943, with the DB 603. DB 603 engines did not arrive until August 1942 and the prototype did not fly until November 1942.
When Kammhuber saw the prototype, he was so impressed that he immediately ordered it into production over Milch’s objections. Milch – who had rejected the He 219 in January in favor of the Junkers Ju 388J was enraged.
Stability problems with the aircraft were noted but Heinkel overcame these by offering a cash prize to engineers who could correct them. Further changes were made to the armament during the development of the prototype He 219V-series. The dorsal rear defensive guns mounted atop the fuselage and firing directly rearward from a fixed, internally mounted, rear-facing dorsal “step” position, at a point just aft of the wing trailing edge, were removed due to their ineffectiveness. The forward-firing armament complement of the aircraft was increased to two Mauser MG 151/20 20 mm cannon in the wing roots, inboard of the propeller arcs to avoid the need for gun synchronizers, with four more MG 151/20 cannon mounted in the ventral fuselage tray, which had originally ended in a rearwards-facing “step” similar to and located directly under the deleted rear dorsal “step” – this rearwards-facing feature was also deleted for similar reasons.
The Heinkel He 219A-0 model featured a bulletproof shield that could be raised in the front interior cockpit, hiding the entire bottom portion of the windscreen, providing temporary pilot protection and leaving a sighting slot by which the gunsight could be aimed at a bomber. Production prototypes were then ordered as the Heinkel He 219A-0 and quickly progressed to the point where prototypes V7, V8 and V9 were handed over to operational units in June 1943 for testing.
The earlier prototypes, with four-blade propellers for their DB 603 engines (also used on the Fw 190C prototypes, with the same DB 603 engine) had blunt, compound-curvature metal nose cones also used for production-series He 219A airframes. The initial examples of these nose cones possessed cutouts for their use with the quartet of forward-projecting masts for the “Matratze” (“Mattress”) 32-dipole radar antennae on the noses of at least the first five prototypes, used with the early UHF-band “Lichtenstein” B/C or C-1 radar installation. These early He 219V-series prototype airframes also had cockpit canopies that did not smoothly taper aftwards on their upper profile, as on the later production He 219A-series airframes, but instead ended in a nearly hemispherically-shaped enclosure. The fourth prototype, He 219 V4, equipped with the earlier canopy design, had a small degree of internal metal framing within the rearmost hemispherical canopy glazing, apparently for a rear dorsal weapons mount or sighting gear for the deleted fixed “step”-mount rearwards-firing armament.
The first major production series was the Heinkel He 219A-0, although initially the pre-production series, it matured into a long running production series, due to numerous changes incorporated into the design, along with the cancellation of several planned variants. Production problems as a result of Allied bombing in March meant the A-0 did not reach Luftwaffe units until October 1943. The A-0 was usually armed with two 20 mm MG 151/20 cannon in the wing roots and up to four 20 mm or 30 mm cannon in a ventral weapons bay. The first 10–15 aircraft were delivered with the 490 MHz UHF-band FuG 212 “Lichtenstein” C-1radar with a 4 × 8-dipole element “Matratze” antenna array. 104 Heinkel He 219A-0s were built until the summer of 1944, the majority of them at EHW (Ernst Heinkel Wien) or Heinkel-Süd in Wien-Schwechat (Ref.: 24).

Reconnaissance, Trainer, Observation

Nakajima E8N2 ‘Dave’, Training Unit, Kyushu (Wings Models, Vacu-formed)

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TYPE: Ship-borne reconnaissance floatplane, Trainer

ACCOMMODATION: Crew of two

POWER PLANT: One Nakajima Kotobuki 2 KAI 2 radial engine, rated at 630 hp

PERFORMANCE:  186 mph

COMMENT: The Nakajima E8N was developed as a replacement for the same company’s E4N and was essentially an evolutionary development of the earlier type, with revised wings of lesser area and taller tail surfaces. Seven prototypes were constructed, under the company designation MS, first flying in March 1934. These were duly engaged in comparative trials against competitors from Aichi and Kawanishi.
The MS was ordered into production, designated Navy Type 95 Reconnaissance Seaplane Model 1 in October 1935. A total of 755 E8Ns were built by Nakajima and Kawanishi, production continuing until 1940. Operating as a catapult-launched reconnaissance aircraft the E8N was subsequently shipped aboard all the capital ships then in service, battleships, cruisers and aircraft tenders. It was used successfully in the Second Sino-Japanese War and distinguished itself on several occasions by destroying opposing Chinese fighters. Occasionally the aircraft was operated as a dive-bomber but was more often employed as a reconnaissance and artillery spotting aircraft.
One E8N was purchased in early 1941 by the German Naval Attaché to Japan, Vice-Admiral Wenneker, and dispatched on board “KM Münsterland” to rendezvous with the German auxiliary cruiser “Orion” at Maug Island in the Marianas. The meeting occurred on 1 Feb 1941, and “Orion” thus became the only German naval vessel of the Second World War to employ a Japanese float plane.
Some aircraft remained in service with the fleet at the outbreak of the Pacific War, and one flew reconnaissance from the battleship Haruna during the Battle of Midway. The type was coded “Dave” by the Allies. Later, they were replaced by more modern aircraft such as the Aichi E13A and the Mitsubishi F1M and the remaining aircraft were reassigned to second-line duties for instance communications, liaison and training (Ref.: 24).

Reconnaissance

DFS 346 (Huma Models)

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TYPE: High-speed, high-altitude reconnaissance aircraft

ACCOMMODATION: Pilot only, in prone position

POWER PLANT: One Walter HWK 109-509 liquid-fuel rocket, rated at 3,400 kp thrust

PERFORMANCE: 560 mph (verified), 1,723 mph (estimated)

COMMENT: The DFS 346 was a German rocket-powered swept-wing aircraft subsequently completed and flown in the Soviet Union after WW II. It was designed by Felix Kracht at the Deutsche Forschungsanstalt für Segelflug (DFS, “German Research Institute for Sailplanes”). The prototype was still unfinished by the end of the war and was taken to the Soviet Union where it was rebuilt, tested and flown.
The DFS-346 was a midwing design of all-metal construction. The front fuselage of the DFS 346 was a body of rotation based on the NACA-Profile 0012-0,66-50. The middle part was approximately cylindrical and narrowed to the cut off to accommodate vertically arrayed nozzles in back. Probably for volume and weight reasons the DFS-346 was equipped with landing skids, both in the original German design and in the later Soviet prototypes; this caused trouble several times.
The wings had a 45° swept NACA 0012-0,55-1,25 profile of 12% thickness. The continuously varying profile shape caused a stall in certain flight conditions, which caused complete loss of control. This was later corrected by use of fences on the top of the wings.
The DFS 346 was a parallel project to the DFS 228 high-altitude reconnaissance aircraft, designed under the direction of Felix Kracht and his team at DFS. While the DFS 228 was essentially of conventional sailplane design, the DFS 346 had highly-swept wings and a highly streamlined fuselage that its designers hoped would enable it to break the sound barrier.
Like its stablemate, it also featured a self-contained escape module for the pilot, a feature originally designed for the DFS 54 prior to the war. The pilot was to fly the machine from a prone position, a feature decided from experience with the first DFS 228 prototype. This was mainly because of the smaller cross-sectional area and easier sealing of the pressurized cabin, but it was also known to help with g-force handling.
The DFS 346 design was intended to be air-launched from the back of a large mother ship aircraft for air launch, the carrier aircraft being the Dornier Do 217K as with the DFS 228. After launch, the pilot would fire the Walter HWK 109-509B/C twin-chamber  engine to accelerate to a proposed speed of Mach 2.6 and altitude of 100,000 ft. This engine had two chambers — the main combustion chamber as used on the earlier HWK 509A motor; but capable of just over two short 2,000 kp of thrust at full power, and the lower-thrust “Marschofen”, (Cruise chamber = throttleable chamber of either 300 kp (B-version) or 400 kp (C-version) top thrust levels mounted beneath the main chamber. After reaching altitude, the speed could be maintained by short bursts of the lower “Marschofen” (cruise chamber).
In an operational use the plane would then glide over England for a photo-reconnaissance run, descending as it flew but still at a high speed. After the run was complete the engine would be briefly turned on again, to raise the altitude for a long low-speed glide back to a base in Germany or northern France.
Since the aircraft was to be of all-metal construction, the DFS lacked the facilities to build it and construction of the prototype was assigned to Siebel Werke located in Halle, where the first wind tunnel models and partially built prototype were captured by the advancing Red Army.
On 22 October 1946, the Soviet OKB-2 (Design Bureau 2), under the direction of Hans Rössing and Alexandr Bereznyak, was tasked with continuing its development. The captured DFS 346, now simply called “Samolyot 346” (“Samolyot” = Aircraft) to distance it from its German origins, was completed and tested in TsAGI wind tunnel T-101. Tests revealed some aerodynamic deficiencies which would result in unrecoverable stalls at certain angles of attack. This phenomenon involved a loss of longitudinal stability of the airframe. After the wind tunnel tests, two wing fences were installed on a more advanced, longer version of the DFS-346, the purpose of fences was to interrupt the spanwise movement of airflow that would otherwise bring the boundary-layer breakdown and transition from attached to stalled airflow with loss of lift and increase of drag.
This solution was used on the majority of the Soviet planes with sweptback wings of the 1950s and 1960s. In the meantime, the escape capsule system was tested from a North American B-25J “Mitchell” piston engine medium bomber and proved promising. Despite results from studies showing that the plane would not have been able to pass even Mach 1, it was ordered to proceed with construction and further testing.
In 1947, an entirely new 346 prototype was constructed, incorporating refinements suggested by the tests. This was designated “346-P” (“P” for planer = “glider”). No provision was made for a power plant, but ballast was added to simulate the weight of an engine and fuel. This was carried to altitude by a Boeing B-29 “Superfortress” captured in Vladivostok and successfully flown by Wolfgang Ziese in a series of tests. This led to the construction of three more prototypes, intended to lead to powered flight of the type.
Newly built “346-1“ incorporated minor aerodynamic refinements over the 346-P, and was first flown by Ziese on September 30, 1948, with dummy engines installed. The glider was released at an altitude of 9700 m, and the pilot realized that he hardly could maintain control of the aircraft. Consequently, while attempting to land, he descended too fast (his speed was later estimated at 310 km/h). After first touching the ground he bounced up to a height of 3–4 m and flew 700–800 m. At the second descent, the landing ski collapsed and the fuselage hit the ground hard.
The pilot seat structure and safety belt proved to be very unreliable, because at the end of a rough braking course Ziese was thrown forward and struck the canopy with his head, losing consciousness. Luckily, he wasn’t seriously injured, and after treatment in hospital he was able to return to flying. Accident investigation research team came to the conclusion that the crash was a result of pilot error, who failed to fully release the landing skid. This accident showed that the aircraft handling was still very unpredictable, as a result, all rocket-powered flights were postponed until pilots were able to effectively control the aircraft in unpowered descent, requiring further glide flights.
The damaged 346-1 was later repaired and modified to 346-2 version. It was successfully flown by test pilot P. Kazmin in 1950-1951 winter, but nonetheless these flights also ended “on fuselage”. Furthermore, after the last flight of these series, the airframe again required major repairs. On 10 May 1951, Ziese returned to the program, flying final unpowered test flights with the 346-2, and from 6 June, unpowered tests of the 346-3 without accidents.
By the mid-1951 346-3 was completed, and Ziese flew it under power for the first time on 13 August 1951, using only one of the engines. Continuing concerns about the aircraft’s stability at high speeds had led to a speed limit of Mach 0.9 being placed during test flights. Ziese flew it again on 2 September and 14 September. On this last flight, however, things went drastically wrong. Separating from the carrier plane at 9,300 meters (30,500 ft) above Lukovici airfield, the pilot fired the engine and accelerated to a speed of 900 km/h (560 mph). The rocket engine worked as expected, and 346-3, quickly accelerating, started ascending and soon had flown in very close proximity of its carrier aircraft. Ziese then reported that the plane was not responding to the controls, and was losing altitude. Ground control commanded him to bail out. He used the escape capsule to leave the stricken aircraft at 6,500 meters (21,000 ft) and landed safely by parachute. With the loss of this aircraft, the 346 program was abandoned (Ref.:24).

Helicopter

Sikorsky HO2S-1 (Unicraft, Resin)

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TYPE: Helicopter

ACCOMMODATION: Crew of one or two

POWER PLANT: One Pratt & Whitney R-985 Wasp Junior  air-cooled radial piston engine, rated at 450 hp

PERFORMANCE: 106 mph

COMMENT: The Sikorsky R-5 (after WW II designated H-5 and also known as S-48, S-51 and by company designation VS-327) is a helicopter developed by Sikorsky Aircraft Corporation in 1943. It was used by the United States Army Airforce (USAAF), later U.S. Airforce (USAF) as well as the U.S. Navy and U.S. Coast Guard (with the designations HO2S and HO3S).
It was designed to provide a helicopter having greater useful load, endurance, speed, and service ceiling than the Sikorsky R-4. The R-5 differed from the R-4 by having an increased rotor diameter and a new, longer fuselage for two persons in tandem, though it retained the R-4’s tailwheel-type landing gear. Larger than the R-4 or the later R-6, the R-5 was fitted with a more powerful Pratt & Whitney Wasp Junior 450-hp radial engine, and quickly proved itself the most successful of the three types.
The first XR-5 of four ordered made its initial flight on August 1943. In March 1944, the Army Air Forces ordered 26 YR-5As for service testing. Additionally, the U.S. Navy ordered three R-5As as the HO2S-1 for evaluation tests.
In February 1945, the first YR-5A was delivered. This order was followed by a production contract for 100 R-5s, outfitted with racks for two litters (stretchers), but only 34 were actually delivered. Of these, fourteen were the R-5A, basically identical with the YR-5A. The remaining twenty were built as the three-place R-5D, which had a widened cabin with a two-place rear bench seat and a small nose wheel added to the landing gear, and could be optionally fitted with a rescue hoist and an auxiliary external fuel tank. Five of the service-test YR-5As helicopters were later converted into dual-control YR-5Es.
Sikorsky soon developed a modified version of the R-5, the S-51, featuring a greater rotor diameter, greater carrying capacity and gross weight, and a redesigned tricycle landing gear configuration; this first flew on February 1946. With room for three passengers plus pilot, the S-51 was initially intended to appeal to civilian as well as military operators, and was the first helicopter to be sold to a commercial user. Eleven S-51s were ordered by the USAF and designated the R-5F, while ninety went to the Navy as the HO3S-1, commonly referred to as the ‘Horse’.
By the time production ceased in 1951, more than 300 examples of all types of the H-5 had been built (Ref.: 24).

Fighter

Messerschmitt Me 163B V41 “Komet“ („Comet“), Erprobungskommando 16, (Heller)

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TYPE: Rocket-powered interceptor

ACCOMMODATION: Pilot only

POWER PLANT: One Walter HWK 109-509A-2 liquid-fuel rocket engine rated between 1,500 kp to 100 kp full variable

PERFORMANCE: 559 mph at all altitudes

COMMENT: The Messerschmitt Me 163 “Komet” (“Comet”) was a German rocket-powered interceptor aircraft. Designed by A. Lippisch, it was the only rocket-powered fighter aircraft ever to have been operational and the first piloted aircraft of any type to exceed 1000 km/h (621 mph) in level flight. Its performance and aspects of its design were unprecedented. The Messerschmitt Me 163 “Komet” was among the most technically advanced and inherently dangerous military aircraft ever to see service. The radical ‘tailless’ design was developed by Dr Alexander Lippisch as the DFS 194 at the Deutsche Forschungsanstalt für Segelflug, (German Research Institute for Sailplanes) at Darmstadt in the 1930s. In January 1939, project work on the DFS 194 was transferred to Messerschmitt AG at Augsburg responsible for fitting a rocket motor. Lippisch also moved to Messerschmitt AG to head the development project team. The rocket-powered sailplane DFS 194 made its first flight on August 1940 what was very successful. Although Messerschmitt was not impressed by the concept of a rocket-powered interceptor, Lippisch and his team continued work on the project. Officially designated Messerschmitt Me 163 the aircraft was first flown under rocket power in 1940 becoming the first aircraft to exceed 1000 km/h, experiencing control problems on the edge of the sound barrier.
Five prototype Messerschmitt Me 163A V-series aircraft were built, adding to the original DFS 194 (V1), followed by eight pre-production examples designated as Me 163 A-0. These aircraft were intensively tested by the Luftwaffe and although its extraordinary acceleration, climbing characteristics and speed inspired the authorities the handling of this tiny aircraft especially during take-off and landing showed tremendous problems. The rocket engine gave power for only a few minutes and the rest of the flight had to be continued as a glider.
Five prototypes and eight pre-production examples were followed by 30 completely redesigned production aircraft Messerschmitt Me 163B-0. These aircraft were armed with two 20 mm MG 151/20 cannon and some of these were allocated to “Erprobungskommando16” (EKdo 16) (“Testing-command 16”) that was formed March 1943 in Peenemünde-West, as a test unit for the rocket fighter, and later based at the Luftwaffe airfield in Bad Zwischenahn for a considerable period of time. This EKdo 16 had some of the aircraft painted completely in red and was the first Luftwaffe unit to perform a combat mission.
The performance of the Me 163 far exceeded that of contemporary piston engine fighters. At a speed of over 200 mph the aircraft would take off, in a so-called “Scharfer Start” (“sharp start”, “sharp take-off”) from the ground, from its two-wheeled dolly. The aircraft would be kept at level flight at low altitude until the best climbing speed of around 420 mph was reached, at which point it would jettison the dolly, retract its extendable landing skid and then pull up into a 70° angle of climb, to a bomber’s altitude. It could go higher if required, reaching 39,000 ft in an unheard-of three minutes. Once there, it would level off and quickly accelerate to around 550 mph or faster, which no Allied fighter could match. Flight endurance under power was just eight minutes after which the aircraft became a glider, and the time available to attack enemy aircraft using  two 20mm cannons was very limited. Once the rocket’s fuel supply was exhausted the Me 163B “Komet” was an easy target for fighter aircraft, particularly during the landing phase (Ref.: 24).

Reconnaissance, Trainer, Observation

Kawanishi E7K2 (“Alf”), (Tamiya)

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TYPE: Reconnaissance floatplane

ACCOMMODATION: Crew of three

POWER PLANT: One Mitsubishi “Zusei” 11 radial engine, rated at 870 hp

PERFORMANCE: 171 mph

COMMENT: The Kawanishi E7K was a Japanese 1930s three-seat reconnaissance floatplane. It was allocated the reporting name “Alf” by the Allies of WW II.
In 1932 the Imperial Japanese Navy requested the Kawanishi Aircraft Company to produce a replacement for the company’s Kawanishi E5K. The resulting design, designated the Kawanishi E7K1, was an equal span biplane powered by a 620 hp “Hiro Type 91W-12 liquid-cooled inline engine. The first aircraft flew on 6 February 1933 and was handed over to the navy for trials three months later. It was flown in competition with the Aichi AB-6 which was designed to meet the same 7-Shi requirement. The E7K1 was ordered into production as the Navy Type 94 Reconnaissance Seaplane and entered service in early 1935. It became a popular aircraft, but was hindered by the unreliability of the “Hiro” engine. Later production E7K1s were fitted with a more powerful version of the “Hiro 91”, but this did not improve the reliability. In 1938 Kawanishi developed an improved E7K2 with a Mitsubishi “Zuisei 11” radial engine. It first flew in August 1938 and was ordered by the Navy as the Navy Type 94 Reconnaissance Seaplane Model 2. The earlier E7K1 was renamed to Navy Type 94 Reconnaissance Seaplane Model 1.
The type was used extensively by the Japanese Navy from 1938 until the beginning of the Pacific War, when E7K1 were relegated to training duties but the E7K2, despite their obsolescence, remained in first-line service until 1943. The aircraft was initially used for convoy escort, anti-submarine patrol and reconnaissance. Later in the war, the E7K2s were retained in the liaison and training role and as mother aircraft for the MXY4 radio-controlled target plane. Also both versions were used in Kamikaze operations in the closing stages of the war (Ref.: 1, 24).

Reconnaissance

DFS 228 V1 (Huma Models)

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TYPE: Rocket powered high-altitude reconnaissance aircraft

ACCOMMODATION: Pilot only in prone position in pressurized cockpit

POWER PLANT: One Walter HWK 109-509 bi-fuel liquid rocket engine, rated at 1,650 kp at 40,000 ft

PERFORMANCE: 435 mph at 75,459 ft

COMMENT:   Beginning in 1940, the DFS (Deutsches Forschungsinstitut für Segelflug, German Research Institute for Sailplanes) started an ambitious program to achieve supersonic flight. Since the only engines powerful enough and available at the time were rocket engines, it was realized that the solution was to have the assault on the sound barrier take place at a high altitude. It was decided to divide the program into three sections:
The first part was concerned with developing and testing of the pressurized cockpit section, the method of pilot escape in case of emergency and performance testing of rocket engines at high altitudes.
The second part was to discover the performance of various sweptback wing configurations. The DFS acquired the Heinkel P.1068 designs for a four-engined turbojet bomber with various wing sweep angles.
The third and last part was to actually build a supersonic aircraft with information learned in the above two steps, which was eventually to become the DFS 346.
The DFS decided to design a new aircraft (although much was learned in an earlier design, the DFS 54) to investigate the first part of their three-step program. Thus, in 1941, the RLM assigned the number 228 to the aircraft, and requested that the DFS 228 also be designed for high-altitude reconnaissance duties as well as research work.
The first prototype of the DFS 228 (coded D-IBFQ) was completed in 1943 by the DFS, although the control sections and landing skid were built by Schmetz Company. The fuselage of the DFS 228 V1 consisted of three circular sections: the nose section containing the cockpit; a center section which contained the landing skid, fuel tanks and a Zeiss infra-red camera; and the tail section with the Walter HWK 509A-1 or A-2 rocket engine. The wing was attached at the mid-fuselage point, and featured 4.5 degrees of dihedral. Wooden construction was used for the entire wing, with a single laminated wooden spar running from wingtip to wingtip, wooden ribs and a plywood covering.  Wide-span divided ailerons were fitted to the wing (the inner section acted as landing flaps), and lift spoilers were also fitted to the upper and lower wings. A conventional tail unit was used, also with all wooden construction. Landing was done on a retractable skid. Since the DFS 228 was to operate in extremely high altitudes, a completely pressurized cockpit was designed. Although it was thought at first that the pressure cabin could be of wooden construction, a metal compartment was built after the wooden one failed to hold sufficient pressure. The nose section was double-walled constructed with aluminum foil insulation. The V1 prototype had a conventional seated pilot’s position, but the V2 and later aircraft were to have a prone pilot position, due to the difficulty of of sealing such a large compartment with the pilot seated upright. All glazed areas were made of double layered Plexiglas and were provided with warm air circulation between layers to prevent frosting of the Plexiglas.
After pressure sealing problems became apparent on the V1 cockpit, it was decided to go with a prone pilot. An adjustable horizontal couch was provided for the pilot to lay on; all controls, oxygen supplies and cockpit equipment mounted directly to the steel tube structure which was then attached directly to the main fuselage bulkhead at the back of the cockpit. This also had the added advantage of keeping the pressurized area small. Thus it was easier to keep sealed. The new cockpit arrangement was incorporated in to the DFS 228 V2 and later aircraft.
A very interesting flight plan was arranged for the operational recognizance DFS 228. It was to be mounted above (or could be towed behind) a carrier aircraft (usually a Do 217K), where it was then carried to approximately 32.808 feet. Upon release, the DFS 228 would then ignite its rocket engine until an altitude of about 75.460-82.021 feet was reached. By this time, the DFS 228 would be over its photographic target area and after its reconnaissance mission was fulfilled, the aircraft would then make a long glide back to base.
In the case of an emergency at high altitudes, the complete pressurized nose section (with all life support equipment attached) could be jettisoned by firing four explosive bolts, or it could take place automatically when the cockpit pressure dropped below a minimum level. An automatic parachute would then deploy to stabilize and slow the descent. When a safe altitude was reached, the pilot was ejected by compressed air, and would then descend to the ground using his personal parachute. This escape procedure was successfully tested by the Soviets after the war, with a captured DFS 346, which had a similar escape system.
DFS 228 V1 flight trials were made at Hörsching, southwest of Linz, by the DFS and also by Erprobungsstelle Rechlin in late 1944. Over 40 test flights were made, and although powered flight was to take place in February 1945, none were actually made using rocket power, and none exceeded 32.808 feet. It was in these tests that the upright pilot’s position was found to be unsuitable for proper cockpit pressurization. The decision was made to go with the prone position cockpit, and was included into the DFS 228 V2, which was built and also flight tested.
The main faults found with the 228 were that it suffered from poor aileron effectiveness at high altitudes and that the elevators were very sensitive. Other than the early pressurization problems, the general handling was satisfactory and the problems would not hamper the intended role of the aircraft. A potential problem could have arisen with the use of the Walter HWK 509A1 or A-2 rocket engines, due to the fact that the flight profile meant for the rocket engine to be intermittently operated, and the possibility existed of valves and pumps freezing up at the extreme altitudes and low temperatures in which the flight was to take place. Of course, newer rocket engines were continually being developed, and perhaps some sort of heating system or the possibility of using M-Stoff and A-Stoff (methanol and oxygen) for fuels, which could have operated at much lower temperatures, could have been developed.
Although powered flight had not been attempted at the time of Germany’s collapse, the construction of a pre-production batch of 10 DFS 228A-0 aircraft had begun at Griesheim, near Darmstadt.
The DFS 228 V2 was destroyed at Hörsching in May 1945, only the forward section had parts worth salvaging. The DFS 228 V1 survived the war, and was surrendered at Ainring in the US Zone of Occupation. On June 18, 1945, it was taken by road to the US Air Technical Intelligence Unit at Stuttgart. It was later sent to the RAE Farnborough in June 1946, and although allegedly was sent to the scrap pile in 1947, another report has the DFS 229 V1 being sent to Slingsby Sailplanes Ltd. at Kirkbymoorside in Yorkshire. Strangely enough, Slingsby offered a design for their T44, a stratospheric research sailplane which incorporated several DFS 228 features, including the detachable pressurized cockpit section (Ref.: 17).

Medium Bomber, Postwar

North American AJ-1 “Savage”, Naval Air Test Center, Patuxent River, (Anigrand Models, Resin)

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TYPE: Carrier-borne medium bomber

ACCOMMODATION: Crew of three

POWERPLANT: Two Pratt & Whitney R-2800-44W Double Wasp radial engines, rated at 2,400 hp each plus one Allison J33-A-10 turbojet engine, rated at 2,040 kp thrust

PERFORMANCE: 471 mph

COMMENT: The North American AJ-1 “Savage” was designed shortly after WW II to carry atomic bombs and this meant that the bomber was the heaviest aircraft thus far designed to operate from an aircraft carrier.
At the end of World War II, the U.S. Navy began a design competition on August 1945 for a carrier-based bomber which could carry a 4,536 kg bomb that was won by North American Aviation. Later that year, the Navy decided that it needed to be able to deliver atomic bombs and that the AJ Savage design would be adapted to accommodate the latest Mark 4 nuclear bomb the next step in development from the more sophisticated imploding Plutonium sphere design Mark 3 “Fat Man” used on Nagasaki. A contract for three XAJ-1 prototypes and a static test airframe was awarded on June 1946. The first prototype made its maiden flight two years later on July 1948. That same year the US Navy began an interim capability program employing the Lockheed P-2 “Neptune” carrying a crash program reproduction of the smaller simpler all uranium ‘gun’ design Mark 2 “Little Boy” nuclear bomb as its first carrier launched nuclear bomber aircraft until the “Savage” was in service. The “Neptune” launched using Jet Assisted Take-Off (JATO) rockets but could not land on existing carriers; if launched they had to either ditch at sea after its mission or land at a friendly airbase.
The AJ-1 was a three-seat, high-wing monoplane with tricycle landing gear. To facilitate carrier operations, the outer wing panels and the tailfin could be manually folded. The two piston engines were mounted in nacelles under each wing with a large turbocharger fitted inside each engine nacelle, and an Allison J33-A-10 turbojet that was fitted in the rear fuselage. Only intended to be used for takeoff and maximum speed near the target, the jet was fed by an air inlet on top of the fuselage that was normally kept closed to reduce drag. To simplify the fuel system, both types of engines used the same grade of avgas. Self-sealing fuel tanks were housed in the fuselage and each wing. The aircraft usually carried 300-US-gallon tip tanks and it could house three fuel tanks in the bomb bay with a total capacity of 1,640 US gallons. Other than its 5,400 kg bombload, the bomber was unarmed.
Two of the three prototypes crashed during testing, but their loss did not materially affect the development of the aircraft as the first batch of “Savages” had been ordered on October 1947. The most significant difference between the XAJ-1 and the production aircraft was the revision of the cockpit to accommodate a third crewman in a separate compartment. The first flight by a production aircraft occurred in May 1949 and Fleet Composite Squadron FIVE (VC-5) became the first squadron to receive a “Savage” in September. The squadron participated in testing and evaluating the aircraft together with the Naval Air Test Center (NATC) in order to expedite the “Savage’s” introduction into the fleet. The first carrier takeoff and landing made by the bomber took place from the USS “Coral Sea” on April and August 1950, respectively.
When first deployed, the AJ-1 was too large and heavy to be used by any American aircraft carrier except for the “Midway” class. The modernized “Essex” class carriers with reinforced decks and the very large “Forrestal” class could also handle the “Savage”. The aircraft was not popular aboard ship as it was too big and cumbersome that it complicated any other flight operations the ship was required to conduct. One problem was that the wings had to be folded one at a time by a crewman on top of the fuselage with a portable hydraulic pump, a time-consuming process, so that the bomber could be moved out of the way to allow other aircraft to land or take off. One pilot reported that the AJ-1 was “a dream to fly and handled like a fighter”, when everything was working properly. The aircraft, however, was not very reliable, possibly because it was rushed into production before all the problems could be ironed out. The bomber was replaced by the Douglas A3D “Skywarrior” beginning in 1957. In total140 aircraft were built plus three prototypes (Ref.: 24).

Reconnaissance, Helicopter, Observation

Focke-Wulf Fw 186 (Planet Models, Resin)

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TYPE: Autogiro, reconnaissance, observation

ACCOMMODATION: Pilot and observer

POWER PLANT: One Argus As 10c air-cooled inline piston engine, rated at 240 hp

PERFORMANCE: 103 mph

COMMENT: German helicopter development began with Focke-Wulf’s acquisition of the rights to manufacture Cierva autogyros during the 1920’s. Over 30 Cierva C.19 and C.30 autogyros were built during the late 1920’s and early 1930’s, and from this experience, Heinrich Focke, the engineering half of the Focke-Wulf company, decided to develop an original autogyro design to compete in the Luftwaffe’s contest to provide a utility-liaison aircraft. The Focke-Wulf entry, designated Fw 186, was essentially a Focke-Wulf Fw 56 “Stösser” (Goshawk) parasol wing advanced trainer, with wings removed, tail unit and landing gear redesigned, and configured for two seats in tandem. The engine remained unchanged, with a clutch arrangement installed to start the blades rotating for takeoff. An autogyro, similar in principle to today’s gyrocopters, uses the main power plant for forward thrust, while the rotors freewheel in flight. The aircraft could take off and land in very short distances, but it could not hover or take off and land vertically.
The first flight of the Focke-Wulf  Fw 186 was on July 1939 and although very successful, it was beaten out by the Fieseler Fi 156 “Storch” (Stork) for the Luftwaffe contract, and disappeared from the scene afterward. Only two examples were built (Ref.: Planet Models).

Reconnaissance, Helicopter, Observation

Kayaba Ka-1 (Frank-Airmodel, Resin)

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TYPE: Autogyro, reconnaissance, observation

ACCOMMODATION: Crew of two

POWER PLANT: One Argus As 10c air-cooled engine (Ka-1) or Jacobs L-4MA-7 air-cooled radial engine (Ka-2), both rated at 240 hp

PERFORMANCE: 103 mph

COMMENT: By order of the Imperial Japanese Army (IJA) the Kayaba Industry developed an autogyro designated Kayaba Ka-1 for reconnaissance, artillery-spotting, and anti-submarine uses. The design based on an American Kellet KD-1A, which had been imported to Japan in 1939, but which was damaged beyond repair shortly after arrival. Kayaba Industry was tasked by the IJA to develop a similar machine, essentially a repaired Kellet KD-1A but powered by a German Argus As 10c engine and shared similar aspects to the German Focke-Wulf Fw 61, which was first flown in 1936, but only about 20 were produced.
The first Kayaba Ka-1 took off from Tamagawa Airfield in May 26, 1941. In the following Army trials, performance was deemed excellent. Originally, it was planned to send the Ka-1 to spot for the artillery units based in mainland China, but the change of the course of war in that theater rendered those plans meaningless. Instead, a few Ka-1 were sent to the Philippines to perform the duties of liaison aircraft as replacements for the Kokusai Ki-76. Soon, an improved version with a Jacobs L-4MA-7 radial engine was on the production line as Kayaba Ka-2. After some time the IJA finally decided on the best use of these unique aircraft, and the majority of Ka-1 and Ka-2 were pressed into service as anti-submarine patrol aircraft. Pilot training for this duty started in July 1943 with the first batch of 10 pilots graduating in February 1944; followed by another batch of 40 pilots in September 1944.
Originally, the plan was to deploy the Ka-1/Ka-2 from 2D-class cargo ships to spot enemy submarines, but these ships turned out to be too cramped for operations; therefore the Ka-1/Ka-2 unit was assigned to the Army-operated escort carrier Akitsu Maru from August 1944 until her sinking in November 1944. From 17 January 1945 ASW patrols were resumed from an airstrip on Iki Isaland with a maintenance base located at Gannosu Airfield in Fukuoka prefecture. ASW patrols also started from May 1945 from Izuhara airfield on Tsushima Island. These missions helped to protect one of the last operational Japanese sea lanes between the ports of Fukuoka and Pusan. Eventually US carrier-based aircraft began to appear even in the Tsushima Strait, so in June 1945 the Ka-1/Ka-2 units were relocated to Nanao base on the Noto Peninsula, in the Sea of Japan, operating from there until the end of the war. The Ka-1/Ka-2 did not directly sink any submarines during the war however, they were well regarded for issuing submarine warnings
A total of 98 Ka-1 and Ka-2 airframes were produced by the end of war, of them 12 were destroyed before being delivered to the IJA and about 30 never had an engine installed, about 50 were delivered to the IJA, but only 30 were actually deployed. Some sources have stated that 240 were built, but this cannot be verified (Ref.: 24).