Arado Ar 81 The Arado Ar 81 was a German prototype dive bomber . Because the Reich Air Ministry decided to purchase the competing Junkers Ju 87 , only three prototypes of the Ar 81 were completed . Development . In 1934 , the Reich Air Ministry or RLM ( " Reichsluftfahrtministerium " ) initiated two parallel programmes to build new dive bombers for the German air force , to replace the Heinkel He 50 . The first , the so - called " Sofort " or immediate program , aimed to develop an interim dive bomber , and resulted in the production of the Henschel Hs 123 . The second , " Sturzbomber " program , aimed to produce a more definitive aircraft . In January 1935 the formal requirements for this were sent out to German aircraft manufacturers . These had been written around the Junkers Ju 87 , of which the first prototype was already under construction . Indeed the Luftwaffe had already given Junkers an order for 118 aircraft . Nevertheless , two manufacturers received an order to deliver three prototypes of their competing projects : The Heinkel He 118 and the Arado Ar 81 . The Blohm & Voss Ha 137 competed as a private venture . The Ar 81 was the only one of the competitors to be conceived as a biplane . Reportedly this was on the advice of Ernst Udet . There seems to have been some doubt at Arado about the use of this outdated configuration , for alternative designs were made for a monoplane with an inverted gull wing . However , in the end the Ar 81 was built as an all - metal biplane . It was a neat enough design , which looked rather more streamlined than the first prototype of the Ju 87 , and was slightly smaller and lighter . The slender fuselage had a closely cowled Junkers Jumo 210C engine up front with a large radiator bath below it . The wings were relatively short in span and connected by N - struts outboard . Behind the wings , the crew of two sat in a roomy cockpit in with a semi - enclosed canopy , back to back . The rear of the cockpit canopy was open to allow the gunner to freely aim his defensive machine gun . The fixed main landing gears legs were fitted with streamlined covers and spats for the wheels . The tail section was very slender , and the tail of the first prototype , Ar 81V1 , consisted of a tailplane with some dihedral that carried two outboard fins and rudders , to improve the field of fire of the tail gunner . However , testing from the end of 1935 onward revealed serious stability problems . The second prototype was given a raised tailplane without dihedral , braced with struts , but this did not cure the issues , and the third prototype had completely reworked tail , with a boom structure of larger cross - section that carried a tall single tail fin and a large rudder . This prototype also had a Jumo 210Ca engine that drove a two - bladed variable - pitch propeller , instead of the three - bladed fixed - pitch unit fitted to the first two prototypes . The defensive armament of a single fixed MG 17 machine gun , intended to be fitted in the engine cowling , and a MG 15 defensive gun in the rear cockpit , was probably never installed . The same is claimed for the special bomb rack below the fuselage , intended to swing a 250 kg bomb clear of the propeller in a diving attack . However , test pilot Kurt Starck claimed that during the 1936 trials , the Ar 81 was the only aircraft capable of dropping a 500 kg bomb in a vertical dive , which indicates that a bomb rack must have been fitted . In its developed Ar 81V3 form , the Arado design was in several aspects better than the Ju 87 prototypes , including level speed , manoeuvrability , range , and especially rate of climb : It reached 4000 m in eleven minutes , while the Junkers design needed 23 minutes . However , the Ju 87 was a more modern design and its performance could be improved by installing more powerful engines , while the Ar 81 had less development potential . And due to the delay involved in redesigning the tail , the Ar 81V3 only made its appearance in the spring of 1936 , when the RLM had already chosen the Ju 87 .