Aviation of Word War II
Long Range Reconnaissance Aircraft
The Ar 240 heavy fighter was born, like the Me 210/410, in the fall of 1938 as a potential replacement for the Bf 110 that had just entered service. Moreover, the Third Reich Aviation Ministry gave the company complete freedom in the use of advanced technical solutions and technologies.
The concept of the heavy fighter has been worked on for a long time by the technical director of Arado Flyugzeugwerke, Walter Blum. The main highlight of the project developed under his leadership was the use of new ideas in relation to the defensive weapons of the "hunter". In collaboration with Rheinmetall-Borzig, Blum designed the advanced weapon system at that time - a remotely controlled machine-gun mount. This decision made it possible to get rid of the main disadvantage of the defensive armament of the Bf 110 - the lack of cover for the lower-rear hemisphere.
The following year, the company presented a project that takes into account the latest achievements in aerodynamics. The aircraft was a two-seater all-metal monoplane with a high wing loading, a pressurized cockpit, a remotely controlled machine gun mount, a highly mechanized wing with automatic slats and double-slotted flaps. The shape of an air brake in the form of a parachute folding into a tail cone was unusual.
To meet another important requirement for the new heavy fighter - the maximum possible speed - the dimensions and cross-sections of the aircraft were chosen to be minimal. To eliminate the reactive torque of the propellers when using powerful motors, it was planned to use coaxial propellers. At the same time, the cocks were supposed to be tunnel - with an air intake for water radiators. This made it possible to simultaneously cool the gearboxes of the coaxial propellers, but wartime conditions did not allow them to be created ...
With the beginning of the war - September 1 - it was decided to stop work on all aircraft that did not have time to start flight tests, including the Ar 240. Work resumed only at the end of 1939. The first flight of the Ar 240 VI took place on April 30, 1940, and after the second Ar 240 V2 followed for three months. From the very first flight, it became clear that the new "hunter" is unstable in all three axes! Considering that the creator of the aircraft Kozin was considered the main specialist in aircraft control in the "Third Reich", the embarrassment was complete ... The rejection of coaxial propellers immediately made the Ar 240 unstable, and the seemingly successful solution with tunnel cocks played an important role here , since such coca had a greater mass and further increased the reactive moment of the screws. The large rotating mass far in front of the aircraft's center of mass made it unstable in longitudinal and lateral control. In addition, long, narrow ailerons proved to be ineffective. The blows in the wind tunnel showed that the thin wing profile was also to blame. The leading edge had to be thickened with special trims. Unlike the problems with the Me 210, the Ar 240 did not even have to rework the plumage. By the fall of 1940, the modified prototypes were sent to the Luftwaffe test center in Rechlin.
By that time, as a result of the air "battle for England", the Bf 110's inconsistency as a "hunter" had already become obvious. The new machines were urgently required to improve the pilot's view, especially forward and downward, to install pressurized cabins and more powerful defensive weapons. As a result, on the next prototype Ar 240 V3 (KK + CD), design changes were made. The aircraft was designed as a dive bomber and reconnaissance aircraft. The pressurized cockpit was moved forward to the very nose, and to maintain alignment, the tail of the new aircraft was lengthened by 1.2 m by inserting a fuselage section. The wingspan also had to be increased by more than 2 meters. The tail air brake was removed. An additional keel was installed. The slats were also removed (mainly to avoid icing). Like its predecessors, the Ar 240 V3 propulsion system consisted of a pair of DB 601A with a capacity of 1075 hp. with. on takeoff. The aircraft was finally equipped with an FA-13 hydraulic fire control system. In the upper and lower installations, a pair of 7.9 mm machine guns were installed. The bow armament is modeled on the Ar 240 V2. All of these improvements delayed the V3's readiness until late spring 1941, when flight tests revealed some, but insufficient, improvement in handling. Again, alterations were required, the installation of new ailerons. At the end of the summer, Ar 240 V3 entered the long-range reconnaissance group for military trials. The FA-13 system, which performed well on tests, performed poorly in the field and was removed along with the offensive weapons. Instead, a pair of Rb 50/30 cameras was installed, as well as a GM-1 nitrous oxide boost system. Colonel Knemeyer of the reconnaissance group carried out several reconnaissance flights over Britain with this aircraft. High speed and high flight altitude made it possible to avoid countermeasures from fighters.
Meanwhile "Arado" finished the fourth Ar 240 V4 . The Ar-0 flugzeugwerke company in Oschersleben was chosen for the production of the Ar 240A-0 installation series. Metal procurement began. Ar 240 V4 was intended for the role of a dive bomber and reconnaissance aircraft. The armament of the previous version was retained, and suspensions for eight 50-kg bombs were installed under the fuselage. The air brake was again installed, increasing the length of the aircraft from 12.4 to 13 m. The engines were installed DB 603A with a take-off capacity of 1750 hp. Before the completion of the dive bombing tests, it was decided that the reconnaissance was now more needed than the dive bomber. As a result, the first pre-production Ar 240A-01 and -02 (GL + QA and QB), which also had the designation V5 and V6, were completed in the reconnaissance version.
Ar240 A-01 and -02 flew in October 1942. Their aerodynamics were also improved, which improved handling, which is still far from ideal. Although the wingspan and shape of the wing did not change, it was actually redesigned. The wing profile has become close to laminar. As a result, the aircraft's performance has improved immeasurably. The air brake was finally abandoned. Engines of steel DB 601E with a capacity of 1175 hp on takeoff. The offensive armament was reduced to a pair of 7.9 mm machine guns. But the FA-13 armament system with coaxial MG81Z machine guns was retained. The two crew members sat back to back in a pressurized, double-glazed cockpit sealed with inflatable rubber hoses. Eight fuel tanks held 2,300 liters of fuel and could be supplemented with a 600 liter outboard tank. Rb50 / 30 automatic cameras were mounted at the rear of the propulsion nacelles. By this time, the takeoff weight had increased to 9460 kg, and the wing load was at least 300 kg / m² with a wing area of 30 m².
Three more Ar 234-A-O were completed and flown to ArO by October 1942. The first of them, the A-03, was originally equipped with DB601E engines, but was later re-equipped with BMW801TJ - 14-cylinder, radial, air-cooled, turbo-charged, takeoff power 1880 hp with. and 1520 liters. with. at an altitude of 10800 m. Ar 240A-04 and -05 (or A-0 / U1 and U2), made without weapons, had DB603A engines. And by December 1942, she had already prepared 80% of the units and parts at the plant in Oschersleben for the first 40 serial Ar 240A, but Erhard Milch suspended the program.
* - max speed at altitude 8300 m
** - max speed at altitude 11200 m with GM1.
*** - with 600-l fuel tank at cruise speed
**** - with two 670-l fuel tanks
Ar 240. Combat Use.
Despite the cessation of production, the produced aircraft were quickly transferred to combat units. Thus, in December 1942, two Ar 240s conducted reconnaissance of the "Stalingrad cauldron" into which Pauls' 6th Army fell. Ar 240A-01 and -02 were delivered to the 5th Fighter Squadron, which was located in the north of Finland near Petsamo. Aircraft "Arado" conducted reconnaissance of the Murmansk railway. Another Ar 240 from February 1943 operated together with the Ju88 from 3. (F) / 100 as part of the Ostland air command, and from July 1943 as part of the Don air command. In June 1943 I. (F) / 100 also used the Ar 240 in the 6th Air Fleet. In the summer of 1943, Ar 240A-02 was transferred from JG-5 to 2. (F) / 122 at Frazinone, southeast of Rome. After several test flights, the aircraft made its first reconnaissance flight. Soon this part received from I. (F) / 123 in Pergia Ar 240A-04 (A-0 / U1), but it was not used due to problems with the DB 603A engines. After their repair, the plane was returned to Germany. This aircraft, together with Ar240A-05 (A-0 / U2) and Ar 240A-03, was used in the southern sector of the Eastern Front in the 10th Long Range Reconnaissance Regiment and as part of the 1st Aufkl Squadron. Gr.Ob.d.L. Ar240 V7 and V8, which were completed before Milch's verdict in October and December 1942, were prototypes of the Ar 240В-1 reconnaissance aircraft. They are also known under the designations Ar 240B-01 and B-02. The aircraft had the same design as the Ar 240A-0. The engines were DB-605AM with a capacity of 1475 hp. on takeoff. Using the injection of a water-alcohol mixture, the power increased to 1800 hp. Both V7 and V8 had a pair of MG17 machine guns forward and barbets with MG81Z. The latter had another 20 mm MG151 cannon in front.
The creation of the Ar 240 reconnaissance variant took priority over other variants of this multipurpose aircraft. As a result, the first "hunter" - Ar 240 V9 (or Ar 240C) did not start flight tests until March 1943, that is, three months after the official completion of the program. The engines on it were DB603A-2 with a capacity of 1750 hp.; and 1850 hp. at an altitude of 2100 m. Ar 240 V9 had practically the same design as the A- and B-series, but the wingspan was increased to 16.6 m. The lengthening of the propulsion nacelles led to an overall increase in the length of the aircraft to 13.3 m. armament consisted of four 20-mm MG 151 cannons. Remote-controlled installations were equipped with twin sets of 13-mm MG 131 machine guns. The empty and take-off weight increased markedly to 8487 kg and 10560 kg, respectively. Despite the increase in wing area by 3.6 m², the load on the wing remained the same. Tests have shown that the flight characteristics have not changed.
Three more experimental aircraft of the C-series were built in parallel: V10 (Ar 240C-02) as a night fighter with another 20-mm MG151 in a WT-151A outboard fairing, FuG202 Liechtenstein locator, and VII and VI2 (Ar 240C-03 and -04) were capable of carrying 1800 kg of bombs and were equipped with a GM1 nitrous oxide injection system, which gave an increase in speed at altitude up to 56 km / h. Other variants were designed, including the Ar 240C-1 with DB603G, the Ar 240C-2 night fighter, the C-3 and C-4 high-speed bomber and reconnaissance aircraft; multipurpose Ar240D with DB614 engines (DB603 with three-speed supercharger); enlarged Ar 240E - bomber with DB603G engines and an equivalent variant of the Ar240F fighter. However, the technical department refused to continue the Ar 240 program. The decision was largely motivated by unsatisfactory controllability and some other problems, which at the time of the program's termination in late 1942 were still unresolved.
"Arado" Аr.440 - two-seat heavy fighter-bomber. The creation of the Ar 440 was considered a completely separate project, although modified units from the Ar 240 were used. The engines were DB 603G, which differed from the DB 603A with a faster supercharger and increased compression ratio, and gave up to 1900 hp on takeoff. with. Structurally, the Ar 440 differed from the Ar 240 by the addition of an additional section just behind the cockpit and a new aft fuselage. The center section was expanded so that the propulsion nacelles were further from the fuselage. The span of the consoles, the stabilizer was also increased, and the propulsion nacelles were lengthened. The engines were fitted with the GM1 system. It was assumed that the DB 627 engines would be installed in the series, which differed from the DB 603G in a two-speed supercharger and a subsequent cooler, developing power up to 2000 hp. on takeoff.
It was understood that the main task of the aircraft would be the role of a fighter-bomber. Armament Ar 440 consisted of two 30mm MK 108 cannons at the root of the wings, two 20mm MG 151 cannons at the nose of the fuselage. The defensive armament consisted of a pair of 13 mm MG 131 machine guns in the upper and lower remote-controlled mounts and one 20 mm MG 151 cannon mounted stationary back. The bomb load was 1000 kg.
The first prototype aircraft was designated Ar 440A-01. Flights began in the summer of 1942. Initial factory tests were encouraging - none of the defects still fought on the Ar 240 showed up on the Ar 440. Three more Ar 440A-0s joined the test program by the end of November, in December and January 1943. Ar 440A-04 was tested by one of the most famous "hunters" - Ober-Lieutenant Thirfelder, who was absolutely delighted with the new aircraft. Despite positive reports from Rechlin, where the new aircraft was being tested, the Technical Department refused to launch the Ar 440 into production. The possibility of releasing the aircraft was considered again 18 months later, after the start of the so-called "urgent fighter program", but by this time the Dornier -335, which promised great prospects, was already approaching, and the Arado fighter finally became history.