You are talking about Do 335, right?
World War II German Dornier Do-335 interceptor (Do-335 Pfeil)
Since Hitler came to power, At the end of World War II, the hopes of the Third Reich were pinned on a variety of "secret weapons." However, most of them were fleeting and only increased the interest of future generations in "archaeological exploration." For example, this missile did not The "arrow" that hit the target - Dornier Do 335.
Since the Wright brothers realized their dream of human flight, every aircraft designer has been racking their brains to pursue higher speeds. A very natural The approach is to increase the number of engines to provide more powerful power. However, if multiple engines are installed horizontally in a conventional manner, it will undoubtedly expand the overall windward area of ??the aircraft, and the increased resistance cannot be underestimated. In addition, if one side of the engine fails, it will also adversely affect the balance of the flight. So think about it from another perspective, if the engines are arranged longitudinally front and rear, and the power is transmitted along the central axis of the aircraft body, so that the aircraft can use the power of two engines in the aerodynamic shape of a single engine, wouldn't this kind of shortcomings be overcome?
As early as before and after World War I, Germany's Claude Dornier designed a series of seaplanes along this line of thinking, with two engines back-to-back in a forward-pulling configuration. In the push-driven form, the Do 15 water reconnaissance aircraft in 1922 was a successful example, and the even more outstanding Do 18 was further developed in 1935. However, the highly protruding engine nacelle obviously could not meet the drag reduction requirements of high-altitude aircraft, so Dornier thought of integrating the power components with the fuselage to truly achieve high-speed requirements. In August 1937, he specially designed this aircraft Concept applied for patent number 728044.
When World War II broke out, Dornier was busy developing new bombers. One of the projects, P.231, was to install an engine on the nose to drive a pulling propeller in a conventional way, and a second one on the rear fuselage. The engine drives the propulsion propeller at the rear of the aircraft, and the key technology lies in the transmission method between the rear engine and the propeller. In order to verify the feasibility, a G?ppingen G? 9 test machine was specially built in 1940 for relevant tests. Its slender body is equivalent to 1/2.5 Do 17, and a 60 kW Hertz is installed at the center of gravity. It is equipped with the Hirth HM 60R engine, and a specially designed extended drive shaft is installed in the rear fuselage, which passes through the tail to drive the propeller. The successful test flight of G? 9 proved the effectiveness and reliability of this rear propulsion method and transmission assembly.
In 1942, the German Aviation Ministry (RLM) put forward the demand for a single-seat high-speed bomber. In May, Dornier participated in the bidding with a revised P.231/3 plan and defeated the Arado. Two strong rivals, Arado and Junkers, were awarded RLM Do 335 R&D contracts. However, the subsequent development was full of twists and turns. Just as the design work was in full swing, in the face of the growing air threat from the Allies, a simple bomber became outdated. The Ministry of Aviation ordered the development direction to shift to one that could adapt to various combat requirements. The multi-purpose fighter aircraft can be flexibly modified into a combat bombing type, a high-speed reconnaissance type, a two-seat night type and a heavily equipped interception type. Although an improvement plan for the Do 335 was quickly produced, the Ministry of Aviation's technical department, which had long had doubts about this unconventional design, was reluctant to renew the contract. Dornier had no choice but to report directly to Air Force Director Erhard Milch. ) Marshal asked for help, which promoted the final completion of the entire design.
In early 1943, Dornier received a contract to build three prototypes. However, jets were more favored at this time. With Hitler's personal intervention, Messerschmitt's Me 262 was mentioned. Although the Do 335 was in many respects an equal priority, production plans for more prototypes supported by Milch were postponed. The first prototype Do 335 V1 (CP UA serial number W.Nr 230001) was completed at Dornier's Friedrichhafen plant and departed from Mengen, Wurttemburg on October 26 ) flew off the ground for the first time, breaking through a high speed of 600 kilometers per hour on its fourth flight. V1 uses two Daimler-Benz DB603A-2 12-cylinder liquid-cooled engines with a power of 1,305 kilowatts, which drive two 3-blade reverse-pitch propellers at the front and rear respectively. The rear engine in the middle of the fuselage passes through an extended transmission The shaft drives the rear propeller, and the corresponding position is also equipped with a radiator and exhaust pipe. Like the G? 9, the Do 335 also uses a front tricycle landing gear. The tail consists of an upper and lower vertical tail and a left and right horizontal tail forming a cross shape. Its wingspan is almost the same length as the fuselage, and the overall outline is quite sturdy. Another very special feature is the use of an ejection escape seat in the cockpit, which was rare at the time. It is powered by compressed air, but the canopy must be opened manually before use. In order to avoid possible harm to the pilot, the explosive bolts set on the upper vertical tail and rear propeller can be detonated before ejection to throw away these dangerous parts. Similarly, in an emergency, the vertical tail can also be thrown away first when a belly landing is required. Lose.
After passing preliminary testing, the V1 was shipped to the Luftwaffe's Rechlin Erprobungstelle for more extensive official evaluation. Although some longitudinally unstable movements were found at high speeds, the pilots who participated in the test gave positive comments on its control performance, maneuverability, especially acceleration and turning characteristics, and believed that the aircraft had no major structural problems. Such a dual-launch configuration is not difficult to master, but poor rearward visibility and insufficient landing gear strength have become the focus of criticism. At that time, Dornier named the Do 335 "Pfeil" (Arrow in English) based on its high-speed performance. However, the long nose and thick body made the pilots prefer to call it "Anteater" (Ameisenbaer). , that is, English Anteater).
In the winter and spring of 1943-44, many prototypes also left the factory for further testing in Oberpfaffenhofen. Some minor improvements were made to V2 (CP UB) and V3 (CP UC), including adjusting the position of the fuel cooler vent, optimizing the shape of the canopy, adding rearview mirrors, and redesigning the main landing gear door. V4 (CP UD) was originally planned as a prototype of the two-seat night-fighting-all-weather Do 435, powered by a 1,865 kW Junkers Jumo 222 engine with an extended wingspan, but was later cancelled. V5 (CP UE) is the first prototype equipped with weapons. The nose is equipped with a 30 mm MK103 cannon with 70 rounds of ammunition. The gun barrel is located on the central axis and passes through the hub of the front propeller. There are also 2 15mm MG151 machine guns, each with 200 rounds of ammunition. V6 (CP UF) and V7 (CP UG) were mainly used for installation and testing of various equipment. V7 was later shipped to Dessau for modification of the Jumo 213 engine, and V8 (CP UH) became the Test platform for the DB603E-1 engine.
In view of the good response from the test flight results, in December 1943, the Ministry of Aviation formulated a production plan to manufacture 310 Do 335s by the end of 1945. The main production line was located in Manzel. However, in March-4 of the following year Allied air raids during that month destroyed most of the equipment, forcing Dornier to return to Oberpfaffenhofen to set up new production lines. By May, production of the Do 335 was accelerated amid signs that an Allied counterattack could launch from France at any time. V9 (CP UI), as a pre-production prototype of the A-0, still uses the DB603A-2 engine, further strengthens the landing gear, and is equipped with a complete weapons system. It is also officially tested at Richlin. However, the continuous bombing by the Allies affected the supply of major components such as engines, and the assembly of the Do 335 was also relatively complicated. Therefore, only 10 A-0 combat bombers rolled off the production line from July to October, and some of them were equipped with test flight units. EK335 (Erprobungskommando 335) for in-depth testing and actual combat evaluation before official service.
In November 1944, the initial production Do 335A-1 entered the production stage, and the engine was upgraded to the 1,342-kilowatt DB603E-1. In addition to the internal bomb bay in the belly of the fuselage, which can accommodate 500 kilograms of bombs, Two hardpoints were installed under the wings, both of which could carry 250 kilograms of bombs or auxiliary fuel tanks. Deliveries began in January 1945. The flight speed of the A-1 type can reach 763 kilometers/hour with afterburner and 685 kilometers/hour without afterburner. The maximum climb rate is 1,400 meters/min. The combat radius is close to 1,500 kilometers. At that time, such performance was enough to stand out from the crowd. The subsequent A-2 and A-3 models were supposed to have improvements to increase their firepower, but these were never implemented. Another Do 335A-0 was modified into an A-4 long-range reconnaissance prototype, with an aerial camera and external fuel tank installed. The engine was replaced with a 1,417-kilowatt DB603G model. There were orders for 10 A-4 production models. , but none of them were completed. The A-6 two-seat night combat version is based on the V10 (CP UK) and is equipped with the FuG 220 "Lichtenstein" SN-2 radar. It adopts a tandem cockpit layout, with the radar operator located in the higher rear cabin. Due to the addition of the cockpit, crew and corresponding electronic equipment, the internal fuel reserves have been reduced, and the overall performance has dropped by about 10% compared to the single-seat model. The weapons remain the same as the single-seat model. In order to increase the concealment of night operations, the exhaust pipe is A flame suppressor is installed on it. Production of the A-6 was transferred to the Heinkel factory in Vienna, but it did not start up at all under heavy bombing, and the plan to match the Fug 217/218 "Neptune" radar did not materialize. The final A-Series variants included the A-10 and A-12 two-seat trainers, of which only a few were completed.
In the winter of 1944-45, the rumbling sound of approaching artillery was already mercilessly hitting the door of Germany, and the once arrogant Luftwaffe fell into a dilemma of being exhausted. The continued deterioration of the war situation prompted Dornier to develop the Do 335 from the A-series combat bomber to the more powerful B-series heavily armed interceptor, the "destroyer". V13 (RP UA) is the prototype of the B-1. The landing gear has been modified again. The front and rear engines are DB603E-1/QE-1 respectively. Using the afterburner device, it can reach a power of 1,566 kilowatts in a short time. The 15mm machine gun was changed to a 20mm cannon, and the B-2 even installed two more 30mm cannons on the wings (five guns firing in unison)! Later, from B-3 to B-8, some were equipped with more powerful engines, and some were changed to two-seat night combat models, but until the defeat, most of them were just semi-finished products that stayed on the production line.
Short of manpower and fuel, Do 335 was unable to be put into actual combat in time even though some of its equipment had been sent to combat conversion units as early as 10 months before the armistice. The only "combat examples" are that some Allied pilots claimed to have encountered such "strange birds" during patrols and fired at them, but were escaped at high speed, and there were several Do 335s parked on the ground when the Allied forces captured the airport. Got shot too. When the U.S. military occupied the Dornier factory at the end of April 1945, less than 40 Do 335s of various models were finally completed, and the total number of unassembled products was only about 90 (the specific number varies slightly from different sources) access). There are also many derivative models on the drawing board, including the Do 535 with a mixed piston/jet engine, the twin-fuselage Do 635 long-range reconnaissance version, the P.256 twin-jet version, etc.
What followed the destruction of the Nazis was the division of the spoils among the victors. In July 1945, as part of the US military's "Operation Sea Horse", the two surviving Do 335A-0 and A group of other "suffering brothers" such as Fw 190, Me 262, and He 219 were loaded onto the escort aircraft carrier "HMS Reaper" and transported back to the United States. Another two A-12s in good condition flew directly to Farnborough, England for research by the Royal Aeronautical Establishment (RAE). The French also collected two B-series prototypes for test flight after repair (see "Testing the Enemy" for details). The article "The Arrow"), but within a few years the remaining Do 335s in Europe were all damaged and scrapped.
The two Do 335s that came to the United States across the ocean were relatively lucky. They were assigned to the U.S. Navy’s Patuxent River Naval Aviation Test Center (Test and Evaluation Center, Patuxent River Naval Aviation Center) in Maryland. Air Station) and underwent detailed evaluation until 1948. One of them (original serial number 240102, the second of the pre-production A-0s) was transferred to the National Air and Space Museum (NASM) in 1961, and has since become dilapidated due to long periods of open storage. After many efforts, the only remaining "arrow" was finally transported back to its "mother nest" - the Dornier Aircraft Company in Munich in October 1974 to undergo a thorough restoration. Many engineers and technicians of the year touched the former aircraft with their own hands. (They were also surprised to find that the explosive device on the fuselage was still active). The refurbished Do 335 made its debut at the Hannover Air Show in May 1976, and was then loaned to the Deutsche Museum in Munich for display. However, it ultimately failed to "return to its roots" and was shipped back to the United States in 1986 for dismantling and preservation by NASM. .
Compared with "unconventional" designs such as XP-55 and Go 229, Do 335 appears more traditional, but still has many innovations. From the initial bomber project to the later multi-purpose models, its performance has been outstanding. Except for a few special models, the Do 335 was the fastest piston propeller fighter at the time. With its long range and strong firepower, it will undoubtedly become the leader of the alliance. It is a nightmare for the military bomber fleet, and there is potential for further development. Due to various unfavorable factors, it is difficult for Do 335 to get a chance to show its talents. In fact, aspects such as the reliability of mechanical components and the safety of ejection seats have not yet been improved, although the manufacturing quantity is larger than other "alternatives" , but never had a chance to prove itself. This "sharp arrow" just drew a dazzling trajectory in the sky and disappeared at the end point without a target.