The Arado Ar 81, a German prototype dive bomber, saw only three prototypes completed as the Reich Air Ministry opted to acquire the rival Junkers Ju 87 instead.
The Ar 81 was the sole competitor designed as a biplane, reportedly following advice from Ernst Udet.
Arado initially had reservations about the outdated configuration, considering alternative monoplane designs with an inverted gull wing.
Nevertheless, the final product was an all-metal biplane with a sleek design, appearing more streamlined than the initial Ju 87 prototype, and being slightly smaller and lighter.
The fuselage was slender, housing a Junkers Jumo 210C engine with a large radiator bath below.
The wings were relatively short, connected by N-struts outboard.
The spacious cockpit accommodated a crew of two, with a semi-enclosed canopy allowing the gunner to freely aim the defensive machine gun.
Streamlined covers and spats were added to the fixed main landing gear legs.
The tail section of the first prototype, Ar 81V1, was slender and featured a tailplane with some dihedral, along with two outboard fins and rudders to enhance the tail gunner’s field of fire.
Despite the initial design, stability issues were discovered during testing in late 1935.
Subsequent prototypes underwent modifications, with the third prototype receiving a completely redesigned tail featuring a larger cross-section boom structure, a single tall tailfin, and a large rudder.
Additionally, this prototype was equipped with a Jumo 210Ca engine powering a two-bladed variable-pitch propeller, a departure from the three-bladed fixed-pitch unit used in the earlier prototypes.
During the 1936 trials, test pilot Kurt Starck asserted that the Ar 81 was the sole aircraft capable of releasing a 500 kg bomb in a vertical dive.
This suggests that a bomb rack must have been installed, despite claims that the defensive armament, including a single fixed MG 17 machine gun and an MG 15 defensive gun, was never actually fitted.
Additionally, the special bomb rack below the fuselage, designed to swing a 250 kg bomb clear of the propeller during a diving attack, was also reportedly not installed.
The Arado design, in its advanced Ar 81V3 version, surpassed the Ju 87 prototypes in various aspects such as level speed, manoeuvrability, range, and notably rate of climb.
It was able to reach an altitude of 4,000 meters (13,000 ft) in just 11 minutes, while the Junkers design required 23 minutes.
However, despite its initial advantages, the Ju 87 had the potential for further improvement by incorporating more powerful engines, whereas the Ar 81 had limited development possibilities.
Unfortunately, due to the time-consuming process of redesigning the tail, the Ar 81V3 was introduced only in the spring of 1936, by which time the RLM had already selected the Ju 87.
Specifications
Crew
2
Length
11.65 m (38 ft 3 in)
Wingspan
11.2 m (36 ft 9 in)
Height
3.57 m (11 ft 9 in)
Wing area
35.6 m2 (383 sq ft)
Empty weight
1,925 kg (4,244 lb)
Gross weight
3,070 kg (6,768 lb)
Powerplant
1 × Junkers Jumo 210Ca,
Inverted V-12 liquid cooled piston engine,
480 kW (640 hp) at 2,700 m (8,900 ft)
Propellers
2 bladed variable pitch propellers
Performance
Maximum speed
345 km/h (214 mph, 186 kn) at 4,000 m (13,000 ft)
Range
693 km (431 mi, 374 nmi) at 4,000 m (13,000 ft)
Service ceiling
7,698 m (25,256 ft)
Time to altitude
At 4,000 m (13,000 ft) in 11 minutes
Armament
Guns
1 × 7.92 mm (0.312 in) MG 17 machine gun fixed in the engine cowling,
1 × 7.92 mm (0.312 in) MG 15 machine gun flexible in the rear cockpit
Bombs
1 × 250 kg (550 lb) bomb on a swinging crutch under the fuselage.
Sources Arado Geschichte Eines Flugzeugwerks-Jorg Armin Kranzhoff. Aircraft of the Luftwaffe 1935-1945, An Illustrated Guide-Jean-Denis GG LaPage. The Official Monogram Painting Guide to German Aircraft, 1935-1945-Kenneth A Merrick & Thomas H Hitchcock.
