Arado Ar 68
Contemporary of the Gloster Gladiator, the Fiat CR.32 and the Polikarpov I-15. the Arado Ar 68 was ordered as a successor to the Heinkel He 51 which, during its brief service career, had acquired a somewhat unenviable reputation among pilots of the fledgeling Luftwaffe. By comparison with the Arado Ar 65F that it had supplanted, the He 51 was certainly no docile hack for the inexperienced, and its low-speed characteristics were anything hut forgiving. Indeed, accident attrition had been high, and there was some reluctance on the part of the Luftwaffe to exchange this, the "devil they knew" for what could only be an even faster and potentially more dangerous "devil" that they didn't know! The Ar 68 did possess a slightly higher wing loading than that of the He 51, it was true, and landing speed was consequently higher, but performance-wise there was little to choose between these two fighters. Sheer speed was not the sole criterion in the selection of a fighter; manoeuvrability was paramount and in this the Arado fighter excelled. With this was coupled a very sturdy structure and, what is more, its handling characteristics were exceptional; yet the Luftwaffe remained unconvinced.

Ernst Udet, eventually tiring of the vacillation, decided that the only way to convince the doubtful elements in the Luftwaffe was to organise a series of mock combats between the He 51 and the Ar 68, Udet himself flying the Arado. His opponent in the He 51 soon found himself out-manocuvred on every count.The Arado appeared to out-turn, out-climb and out-fight the Heinkel effortlessly, and not so many months later, the "HorstWessel" Jagdgeschwader (JG 134) was re-equipping with the Ar 68.

A single-bay biplane of unequal span and chord, the Ar 68 was largely the creation of the Arado Flugzeugwerke's chief designer, Ing Rethel, and the first prototype. the Ar 68a D-IKIN began flight trials at Warnemünde in 1934. Powered by a BMW VI d twelve-cylinder liquid-cooled upright-Vee engine producing 750 hp at sea level for take-off for one minute and having a maximum continuous rating of 550 hp, the Ar 68a was of mixed construction. the wooden wings being plywood- and fabric-covered, and braced by splayed-out N-type interplane struts, and the fuselage was a rectangular welded steel-tube structure, faired to an oval section and covered forward and along the decking with detachable light metal panels and aft on the sides and bottom with fabric. While the handling characteristics of the Ar 68a met the most sanguine expectations, performance was lower than anticipated. forward view for the pilot left something to be desired. and exhaust gases seemed to accumulate in the pilot's cockpit. The answer to all these problems appeared to be offered by the new Junkers Jumo 210 engine. Its inverted-Vee form improved forward view and removed the problem of exhaust gases, and although it offered only 610 hp for take-off, it embodied a supercharger which enabled the engine to maintain this power to 3400 m. One of the first production Jumo 210A engines was mounted in a second prototype of Arado's fighter, the Ar 68b D-IVUS. As was to be expected, the engine suffered its share of teething troubles and built-in drag resulted from the poor design of its radiator bath. However, a new form of radiator which offered an appreciable reduction in drag and. simultaneously, a small amount of residual thrust, was quickly designed and fitted to the third prototype, the Ar 68c (which was also known as the Ar 68 V3 under the system of Versuch ntimbers introduced for experimental aircraft by the RLM).

The Ar 68c was flown for the first time in the summer of 1935 and was the first prototype to carry armament, this comprising two 7.9-mm MG 17 machine guns in the upper cowling of the engine. With the successful completion of armament trials and performance fully meeting the original specification, the Arado Flugzeugwerke was already making preparations for the series production of the fighter as the Ar 68C when the company was informed that its requirements for the Jumo 210A engine could not be fulfilled, several other aircraft mantifacturers having staked their claims for deliveries of the new engine before Arado. In consequence. Arado was forced to revert to the BMW VI engine for the fourth prototype, the Ar 68d (or Ar 68 V4) D-ITAR, but still hopeful of getting deliveries of the Junkers engine, the company fitted a Jumo 210 Da engine offering 690 lip for take-off and with 550 hp available as a normal continuous rating in the fifth aircraft, the Ar 68e (Ar 68 V5) D-ITEP. The Ar 68e was, in fact, a production prototype for the Ar 68E-series fighter, but the impossibility of obtaining supplies of the Junkers engine necessitated the temporary shelving of the Ar 68E in favour of the Ar 68F. an interim model with the BMW VI which began to enter service late in 1936.

Relatively few Ar 68F fighters had been manufactured before an improvement in the Jumo 210 delivery position enabled the Arado Flugzeugwerke to place the Ar 68E on the assembly line with the Jumo 210 Da and, later, Jumo 210 Ea engine of 690 hp for take-off, deliveries of this model commencing in the spring of 1937.

The Ar 68E progressively supplanted the He 51 as the Luftwaffe´s principal first-line fighter, and although the Messerschmitt Bf 109B had been hurriedly despatched to the Condor Legion which was finding its ageing He 51s no match for the nimbler and faster I-15 biplanes and I-16 monoplanes of the Republicans, in 1938 two Ar 68E-l biplanes were sent to Spain for experimental operational trials in the role of night fighter. The Ar 68E fighters flew operationally from La Cenia airfield. equipping Grupo 9 under Capitan Javier Murcia.

The structure of the Ar 68 fighter remained unchanged throughout its development and production life as did also its armament of two MG 17 machine guns with 500 rpg. This armament could be supplemented by a special dispenser housing six SC 10 fragmentation bombs but this was rarely fitted owing to the serious effect that the drag of the installation had on performance. Although by the spring of 1937 the first series production Messerschmitt Bf 109B fighters had begun service evaluation, the Arado Flugzeugwerke was not convinced that the debut of this sleek fighter monoplane had sounded the death knell of the fighter biplane in Germany, and after the Ar 68G had proved abortive owing to the lack of an efficient BMW "altitude" engine, the Ar 68H (D-ISIX) was completed and flown. This differed extensively from its predecessor. Armament was increased to four MG 17 machine guns, two of these being built into the upper wing, a nine-cylinder radial BMW 132 Da engine-a licencebuilt version of the American Pratt & Whitney Hornet-offering 850 hp at take-off supplanted the liquid-cooled engines previously installed, and as a concession to modernity, a sliding cockpit canopy was provided. The maximum speed of the Ar 68H exceeded 248 mph (400 km/h). but by now the RLM was convinced that the biplane configuration had little further to offer aircraft in the fighter category, and the development of landbased fighter biplanes in Germany finally ceased.
Type A, D Prototypes Single seat fighter B, C, E Prototypes Single seat fighter E Single seat fighter F Single seat fighter
Engine 1 BMW VI 750 hp 1 Junkers Jumo 210A 735 hp 1 Junkers Jumo 210Da later Ea 735 hp 1 BMW VI 750 hp
Dimensions Length 9,50 m height 3,30 m span 8,00/11,00 m wingarea 27,30 m2
Weights Empty 1600 kg load 420 kg flying weight 2020 kg Empty 1600 kg load 420 kg flying weight 2020 kg wingloading 74 kg/m2 powerloading 2,75 kg/hp Empty 1600 kg load 420 kg flying weight 2020 kg wingloading 74 kg/m2 powerloading 2,70 kg/hp
Performance   Max. speed 306 km/h at sea level, 335 km/h at 2650 m, 325 km/h at 4000 m, 295 km/h at 6000 m, initial climb rate 12.5 m/sec, time to 6000 m 10 min, service ceiling 8100 m range 500 km Max. speed 330 km/h, 310 km/h at 4000 m, 295 km/h at 6000 m, range 500 km, service ceiling 7400 m
Armament   2 MG 17 with 500 rpg and optional 6 SC 10 bombs in a special dispenser 2 MG 17 with 500 rpg and optional 6 SC 10 bombs in a special dispenser
Type G Single seat fighter (Only Project) H Single seat fighter
Engine High altitude engine 1 BMW 132 Da
Performance Max. speed 400 km/h service ceiling > 9000 m
Armament   4 MG 17 with 500 rpg and optional 6 SC 10 bombs in a special dispenser
5 Prototypes
Seriesproduction 514 of which Erla delivered 76 and Fieseler 63
Arado-Ar 68
Die seit längerer Zeit als Ausbildungsmaschine bei der Luftwaffe . eingesetzte Konstruktion ist als verspannter Doppeldecker ausgeführt, eine Bauweise, die von Arado in den verschiedensten Baumustern gepflegt und weiterentwickelt wurde. Flügel von ungleicher Spannweite, gestaffelt, auf jeder Seite durch einen nach außen geneigten N-Stiel miteinander verbunden. Zwei Trag- und ein Hängekabel.
Oberflügel auf verspanntem Strebenbaldachin gelagert. Flügeltiefe und Dicke über dem Rumpf zur Verbesserung der Sicht kleiner als außen. Holzbauweise mit zwei parallelen Holmen. Spaltquerruder nur am Oberflügel. Der Unterflügel weist an der Hinterkante Klappen zur Verringerung der Landegeschwindigkeit auf.
Rumpf von ovalem Querschnitt. Stahl rohrbau v/eise, Vorderteil und Rücken mit Blech beplankt, sonst Stoffbespannung. Offener Führersitz unter Hinterkante Oberflügel. Leitwerk mit Metallgerippe, Flossen blechbeplankt, Ruder stoffbespannt. Höhenleitwerk ungeteilt, Flosse auf jeder Seite durch einen umgekehrten V-Stiel nach der Kielflosse abgefangen. Beide Ruder besitzen Außenausgleich mit Gegengewichten. Höhenruder mit Trimmklappe versehen.
Festes Einbeinfahrv/erk, OelStoßdämpfer. Räder verkleidet. Spornrolle ebenfalls verkleidet, mit Druckgummi gefedert.
Triebwerk: BMW VI 750 PS mit Heißkühlung. Kühler in einem Schacht unter dem Motor. Brennstoffbehälter von 200 1 im Rumpfvorderteil, Oeltank von 16 1 hinter dem Motor. Eclipse-Starter.
Bestückung: zwei feste, durch den Schraubenkreis feuernde MG, für die zusammen 1000 Schuß Munition mitgeführt v/erden. Magazin für 6 Bomben zu je 10 kg. FT-Anlage für Senden und Empfang.
Spannweite 11 m, Länge 9,5 m, Höhe 3,3 m, Fläche 27,3 m2, Leergewicht 1580 kg, Fluggewicht 2000 kg, Flächenbelastung 73,5 kg/m2, Leistungsbelastung 2,67 kg/PS,
Höchstgeschwindigkeit am Boden 330 km/h, in 4000 m Höhe 310 km/h, in 6000 m 295 km/h, Lande-geschw. 96 km/h, Steigzeit auf 6000 m 16 min, Dienstgipfelhöhe 7400 m, Reichv/eite 500 km, Flugdauer 1,7 Std.