The Arado Ar 240 emerged from a late‑1930s Luftwaffe requirement for a second‑generation Zerstörer—a heavy, twin‑engine, multi‑role combat aircraft intended to surpass the Messerschmitt Bf 110, whose performance and growth potential were already proving inadequate by 1938.
The Reichsluftfahrtministerium (RLM) sought an aircraft capable of high‑speed interception, long‑range reconnaissance, and dive‑bombing, all within a single airframe.
Arado and Messerschmitt were both invited to submit designs, with Messerschmitt offering the Me 210 and Arado proposing a far more ambitious concept built around several advanced technologies the firm had been developing since the mid‑1930s.
Arado’s chief designer, Walter Blume, had long been fascinated by the challenge of integrating defensive armament into high‑speed aircraft without the drag penalties of traditional manned turrets.
His team had also invested heavily in pressurized cockpit technology, travelling-flap high-lift systems, and remote-controlled defensive gun turrets—all of which would be incorporated into the Ar 240. airwar.ru
The result was one of the most technically sophisticated German aircraft projects of the war—yet also one of the most troubled.
Design Philosophy and Technical Innovations
Airframe and Aerodynamics
Arado designed the Ar 240 around the principle of minimising drag at high speed, which led to an unusually small wing area for an aircraft of its weight class.
The wing loading exceeded 330 kg/m², extraordinarily high for the era and far above typical single-engine fighters.
This configuration promised excellent top speed but imposed severe takeoff and landing challenges.
To counteract this, Arado employed the following:
Travelling flaps (a Fowler‑type system that increased wing area when deployed)
Full‑span leading‑edge slats
Ailerons split into upper fixed and lower extending sections
These devices were intended to tame the aircraft’s low-speed behaviour, though in practice they never fully compensated for the wing’s inherent limitations.
Pressurized Cockpit
The Ar 240 featured a fully pressurised cockpit, a rarity among German twin-engine aircraft of the period.
This allowed long‑range reconnaissance missions at high altitude with reduced crew fatigue.
The pressurisation system was integrated into a streamlined, heavily glazed cockpit positioned well forward on later prototypes to improve stability.
Remote-Controlled Defensive Armament
One of the aircraft’s most distinctive features was its remote‑controlled defensive gun system, developed through years of Arado experimentation.
The system used:
A periscopic sight operated by the navigator/gunner
Hydraulically powered turrets mounted in the unpressurized rear fuselage
Pancake‑shaped, low‑drag housings for the guns
Early prototypes used the FA‑9 system with MG 81Z machine guns; later versions adopted the improved FA‑13 system with MG 131s.
Although innovative, the system suffered from reliability issues, especially at altitude, where optics and hydraulics were prone to freezing.
Engines and Cooling System
Most prototypes used Daimler‑Benz DB 601 or DB 603 inline engines.
The cooling system employed annular radiators housed behind large, ducted spinners, giving the aircraft the appearance of a radial‑engined design.
This arrangement reduced drag and was similar to the radiator installations on the Ju 88 and the intended Jumo 222‑powered Ju 288.
Dive-Bombing Equipment
Because the RLM required dive‑bombing capability, Arado installed a rear‑fuselage “petal” dive brake, which opened sideways like a clamshell.
This unusual device extended beyond the tailplane and was inspired by similar experiments on the Dornier Do 217.
Prototype Development and Flight Testing
Early Prototypes (V1–V4)
The first prototype, the Ar 240 V1, flew on 25 June 1940.
It immediately demonstrated severe instability on all three axes, poor low‑speed handling, and chronic engine overheating during taxiing.
Enlarged ailerons, modified dive brakes, and auxiliary radiators were added to subsequent prototypes.
The V3 prototype introduced the first functional remote‑controlled defensive turret system and was used for reconnaissance trials.
The V4 prototype incorporated the dive‑brake system and DB 603 engines.
Refinement Attempts (V5–V12)
Despite continuous modifications—including new wings with thicker, quasi‑laminar profiles—the aircraft remained directionally unstable.
Additional dorsal and ventral fins were tested, and control surfaces were repeatedly redesigned.
Even with these changes, pilots found the aircraft demanding and unpredictable.
Nevertheless, the Ar 240 demonstrated exceptional speed for a two‑seat aircraft.
Some prototypes exceeded 630 km/h, and the later V11/V12 with GM‑1 nitrous oxide boost reportedly approached 700 km/h at altitude.
Operational Use
Although never accepted for mass production, several prototypes and pre‑production aircraft saw limited operational service:
The Ar 240 V3, V5, and V6 were stripped of armament and used as high‑speed reconnaissance aircraft over Britain, where their speed allowed them to evade interception in 1942.
Five Ar 240A‑0 aircraft were delivered for field evaluation in 1943.
Units in Finland, the Eastern Front, and Italy used them for reconnaissance missions, including flights over Murmansk and deep into Soviet territory.
Despite impressive speed, the aircraft’s handling problems, maintenance complexity, and unreliable defensive systems made it unpopular with crews.
Variants
Ar 240A‑0
Pre‑production reconnaissance aircraft: five built. Powered by DB 601E or DB 603A engines. Used operationally in small numbers.
Ar 240B (Proposed)
A planned development with DB 605 engines; never completed.
Ar 240C Series
A major redesign with increased wingspan (16.59 m), DB 603A engines, and significantly heavier armament.
C‑1: Heavy fighter
C‑2: Night fighter with FuG 202 radar
C‑3: Light bomber
C‑4: High‑altitude reconnaissance aircraft
Prototypes V9–V12 represented these configurations.
Despite promising performance, the RLM cancelled further development in 1943.
Arado Ar 440
A heavily revised derivative with a lengthened fuselage and DB 603G engines.
Although superior to the Ar 240, it too was abandoned in favour of the Dornier Do 335.
Performance Summary (Ar 240A‑01)
(Representative figures)
Maximum speed: ~618 km/h
Cruise speed: ~555 km/h
Range: ~2,000 km
Service ceiling: ~10,500 m
Rate of climb: ~9 m/s
Armament:
2 × fixed MG 17 forward
2 × remote MG 81 or MG 131 in dorsal/ventral turrets
Up to 1,800 kg bombs (depending on variant)
Assessment and Legacy
The Arado Ar 240 was one of the most technically advanced German aircraft projects of WWII, incorporating innovations that were ahead of their time.
Yet its ambitious design exceeded what contemporary aerodynamics, materials, and systems engineering could reliably support.
Its key shortcomings included the following:
Chronic instability, even after extensive redesign
Shifting RLM priorities, which increasingly favored simpler, proven designs
Despite its failures, the Ar 240 contributed valuable research data on pressurisation, remote weapon systems, and high‑lift devices, influencing later German aircraft development.
In the end, the Ar 240 stands as a classic example of overambition in wartime aviation design—a machine of remarkable speed and innovation that never overcame its fundamental aerodynamic flaws.
