All posts by Gunther Arnold

DFS 346 (Huma Models)

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 “Mitchel” 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).

Sikorsky HO2S-1 (Unicraft, Resin)

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).

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

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).

Kawanishi E7K2 (“Alf”), (Tamiya)

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).

DFS 228 V1 (Huma Models)

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).

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

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).

Focke-Wulf Fw 186 (Planet Models, Resin)

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).

Kayaba Ka-1 (Frank-Airmodel, Resin)

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).

Kellett YO-60 (LF model, Resin)

TYPE: Autogyro, reconnaissance, observation

ACCOMMODATION: Crew of two

POWER PLANT: Jacob R-915-3 radial engine, rated at 300 hp

PERFORMANCE: 110 mph

COMMENT: The Kellett YO-60 was a military derivative of the civil Kellet KD-1 autogyro built by the Kellett Autogiro Company by order of the United States Army in the late 1930. It had the distinction of being the first practical rotary-wing aircraft used by the United States Army and inaugurated the first scheduled air-mail service using a rotary-wing aircraft.
Using the experience gained in building Cierva autogyros under license the Kellett Autogiro Company developed the KD-1 which was similar to the contemporary Cierva C.30. It had two open cockpits, a fixed tailwheel landing gear and was powered by a 225 hp Jacobs L-4 radial engine. After testing of the prototype a commercial variant designated the Kellett KD-1A was put into production. The KD-1A had a three-bladed rotor with folding blades and a number of minor detail improvements. A KD-1B which was a KD-1A with an enclosed cockpit for the pilot was operated by Eastern Airlines and inaugurated the first scheduled rotary-wing air-mail service on July 1939.
In 1935 the United States Army bought a KD-1 for evaluation and designated it Kellett YG-1, a second aircraft followed which had additional radio equipment and was designated the Kellett YG-1A. These two aircraft were followed by a batch of seven designated Kellett YG-1B.
In 1942 seven more aircraft were bought by the US Army Air Force for use in the observation role as the Kellet XO-60. During initial test phase several improvements were incorporated compared to the KD-1. A new style clutch had discs and used a planetary reduction gear system at the engine with a larger drive shaft running directly from the power takeoff on the engine to the rotor head and the pilot was put in the front seat and added a transparent plastic cover over both cockpits and a large transparent plastic panel in the belly beneath the pilot’s feet. The observer’s seat could swivel so he could ride backwards and work at a small table behind the rear seat. When the observer was not in place, ballast had to be carried in the rear cockpit. Furthermore, the power plant was changed to a Jacobs R-915-3, seven cylinder, air-cooled, radial engine providing 330hp through a Hamilton-Standard constant speed propeller and the engine mount was removable at the firewall. In this way a quick change power plant package could be stocked. The fuselage structure was similar to the earlier KD-1/YG-1. The fairing was different with flatter sides giving the observer better downward vision out the side windows. The enclosure over the two cockpits hinged open and slid to the right to permit entrance and exit from the cockpits on the left.
The model was soon changed from Kellett XO-60 to YO-60 and seven were built. Only six were delivered, one was damaged in a run-up accident and was not repaired.
One YG-1B was modified with a constant-speed rotor and was re-designated the Kellett YG-1C, it was later re-engined with the more powerful R-915 and re-designated again as the Kellett XR-2. The XR-2 was destroyed by rotor ground resonance problems and the evaluation was continued with another modified YG-1B designated the Kellett XR-3. In total app. 24 Kellett autogyros were built for the US Army Air Force.
One Kellet KD-1A been imported to Japan in 1939 and was prototype for the Kayaba Ka-1 and Ka-2 autogyro (Ref. 24).

Focke-Wulf Fw 191 V1 (Airmodel, Vacu-formed)

TYPE: Medium bomber

ACCOMMODATION: Crew of seven

POWER PLANT: Two BMW 801A radial engines, rated at 1,539 hp each

PERFORMANCE: 385 mph at 20,800 ft

COMMENT: The Focke-Wulf Fw 191 was a prototype German bomber of WW II, as the Focke-Wulf firm’s entry for the Bomber B advanced medium bomber design competition. Two versions were intended to be produced, a twin-engine version using the Junkers Jumo 222 engine and a four-engine variant which was to have used the smaller Daimler-Benz DB 605 engine. The project was eventually abandoned due to technical difficulties with the engines
In July 1939, the RLM issued a specification for a high-performance medium bomber (the “Bomber B” program). It was to have a maximum speed of 370 mph and be able to carry a bomb load of 4,000 kg to any part of Britain from bases in France or Norway. Furthermore, the new bomber was to have a pressurized crew compartment, of the then-generalized “stepless cockpit” design (with no separate windscreen for the pilot) pioneered by the Heinkel He 111P shortly before the war and used on most German bombers during the war, remotely controlled armament, and was to utilize two of the new 2,466 hp class of engines then being developed (Jumo 222 or DB 604), with the Jumo 222 being specified for the great majority of such twin-engined designs, that Arado, Dornier, Focke-Wulf and Junkers had created airframe designs to use. The Arado Ar E340 was eliminated. The Dornier Do 317 was put on a low-priority development contract; and the Junkers Ju 288 and Focke-Wulf Fw 191 were chosen for full development.
Overall, the Fw 191 was a clean, all-metal aircraft that featured a shoulder-mounted wing. Two 24-cylinder Junkers Jumo 222 engines (which showed more promise than the DB 604 engines) were mounted in nacelles on the wings. An interesting feature was the inclusion of the Multhopp-Klappe, an ingenious form of combined landing flap and dive brake fitted in four sections to the wing trailing edges, which was developed by engineer H. Multhopp. The entire fuel supply was carried in five tanks located above the internal bomb bay, and in two tanks in the wing between the engine nacelles and fuselage.
The tail section was of a twin fins and rudders design, with the tailplane having a small amount of dihedral. The main landing gear legs retracted to the rear and rotated 90° to lie flat in each engine nacelle with the mainwheels resting atop the lower ends of the gear struts when fully retracted, much like the main gear on the production versions of the Junkers Ju 88 already did. Also, the tailwheel retracted forwards into the fuselage. A crew of four sat in the pressurized cockpit, and a large Plexiglas dome was provided for the navigator; the radio operator could also use this dome to aim the remotely controlled rear guns.
The Fw 191 followed established Luftwaffe practice in concentrating the crew in the nose compartment, also including the nearly ubiquitous “Bola”, inverted-casemate undernose gondola for defensive weapons mounts first used on the Junkers Ju 88A before the war, and in the use of a “stepless cockpit”, having no separate windscreen for the pilot, as the later -P and -H versions of the Heinkel He 111 already did. This was pressurised for high-altitude operations. The proposed operational armament consisted of one 20 mm MG 151 cannon in a chin turret, twin 20 mm MG 151 in a remotely controlled dorsal turret, twin 20 mm MG 151 in a remotely controlled ventral turret, a tail turret with one or two machine guns and remotely controlled weapons in the rear of the engine nacelles. However, different combinations were mounted in the prototype aircraft. Sighting stations were provided above the crew compartment, as well as at the ends of the aforementioned “Bola” beneath the nose.
The aircraft had an internal bomb bay. In addition, bombs or torpedoes could be carried on external racks between the fuselage and the engine nacelles. The design was to have had a maximum speed of 370 mph, a bomb load of 4,000 kg, and a range allowing it to bomb any target in Britain from bases in France and Norway.
It is said that the intention to use electric power for almost all of the aircraft’s auxiliary systems (also a fact for the successful Focke-Wulf Fw 190 fighter), requiring the installation of a large number of electric motors and wiring led to the nickname for the Fw 191 of “Das fliegende Kraftwerk” (the flying power station). This also had the detrimental effect of adding even more weight to the overburdened airframe, plus there was also the danger of a single enemy bullet putting every system out of action if the generator was hit. On its maiden flight early in 1942, the Focke-Wulf Fw 191 V1 showed immediate problems arising from the lower rated engines not providing enough power, as was anticipated. Additional problems occurred with the Multhopp-Klappe, which presented severe flutter problems when extended, and pointed to the need for a redesign. At this point, only dummy gun installations were fitted and no bomb load was carried. After completing ten test flights, the Fw 191 V1 was joined by the similar V2, but only a total of ten hours of test flight time was logged. The 2,466 hp Junkers Jumo 222 engines which would have powered the Fw 191 proved troublesome. In total only three prototype aircraft, V1, V2 and V6, were built. The project was crippled by engine problems and an extensive use of electrical motor-driven systems. Problems arose almost immediately when the Junkers Jumo 222 engines were not ready in time for the first flight tests, so a pair of 1,539 hp BMW 801A radial engines was fitted. This made the Fw 191 V1 seriously underpowered. Another problem arose with the RLM’s insistence that all systems that would normally be hydraulic or mechanically activated should be operated by electric motors.
At this point, the RLM allowed the redesign and removal of the electric motors (to be replaced by the standard hydraulics), so the Fw 191 V3, V4 and V5 were abandoned. The Fw 191 V6 was then modified to the new design, and also a pair of specially prepared Junkers Jumo 222 engines were fitted that developed 2,170 hp for takeoff. The first flight of the new Fw 191 took place in December 1942. Although the V6 flew better, the Junkers Jumo 222 was still not producing their design power, and the whole Jumo 222 development prospect was looking bad due to the shortage of special metals for it. The Fw 191 V6 was to have been the production prototype for the Fw 191A series.
Due to the German aviation engine industry having ongoing problems in producing power plant designs capable of output levels matching or exceeding the 2,100 hp figure throughout the entirety of the war years, that had any demonstrable level of combat-ready reliability, the Jumo 222 engines were having a lot of teething problems, and the Daimler Benz DB 604 had already been abandoned, a new proposal was put forth for the Fw 191B series.
The Fw 191 V7 through V12 machines were abandoned in favor of using the Fw 191 V13 to install a pair of Daimler Benz DB 606 or 610 “power system” engines, which were basically coupled pairs of either DB 601 or 605 12-cylinder engines. Their lower power-to-weight ratio, however, from their 1.500 kg weight apiece for each “power system”, meant that the armament and payload would have to be reduced. It had already been decided to delete the engine nacelle gun turrets, and to make the rest manually operated. Five more prototypes were planned with the new engine arrangement, V14 through V18, but none were ever built, possibly from the August 1942 condemnation by Reichsmarschall H. Göring of the coupled “power system” DB 606 and 610 power plants as “welded-together engines, in regards to their being the primary cause of the unending series of power plant problems in their primary use, as the engines on Heinkel’s He 177A “Greif”, Germany’s only production heavy bomber of World War II.
One final attempt was made to save the Focke-Wulf Fw 191 program, this time the Fw 191C was proposed as a four engined aircraft, using either the 1,322 hp Junkers  Jumo 211F, the 1,332 hp Daimler-Benz DB 601E, the 1,455 hp Daimler-Benz DB 605A or similar rated DB 628 engines. Also, the cabin would be unpressurized and the guns manually operated, with a rear step in the bottom of the deepened fuselage — in the manner of the near-ubiquitous “Bola” gondola used by the majority of German bombers for ventral defense under the nose — being provided for the gunner.
However, at this time, the whole “Bomber B” program had been canceled, due mainly to no engines of the 2,500 hp class being available, which was one of the primary requirements in the “Bomber B” program. Although the Fw 191 will be remembered as a failure, the air frame and overall design eventually proved themselves to be sound; only the underpowered engines and insistence on electric motors to operate all the systems eventually doomed the aircraft. All in all, there were only three Focke-Wulf Fw 191s ever built (V1, V2 and V6), and no examples of the Fw 191B or C ever advanced past the design stage. The RLM kept in reserve for Focke-Wulf the future number: Fw 391 for follow-up designs, but nothing ever developed. The project was eventually scrapped (Ref.: 24).