The Arado Ar E.654 was proposed as a heavy fighter / destroyer platform designed from another Arado product - the Ar 240. Though the Ar 240 model eventually saw operational service with the Luftwaffe (albeit in limited numbers), the Ar E.654 would never see the light of day. Its unconventional engine arrangement provided some technological barriers to contend with so much so that the complex system was eventually shelved altogether.
The E.654 maintained some visual similarities to the Ar 240 with two wing-mounted engine nacelles, a crew of two and a long streamlined fuselage. Whereas the Ar 240 held its Daimler-Benz engines wholly in the wing nacelles, the E.654 attempted to utilize a more complex approach in order to maximize overall streamlining and benefit engine protection. The E.654 was designed to house the twin Daimler-Benz DB 614 OR 627 series engines within the fuselage itself while running the propellers via multiple gear shafts. This approach was highly apparent in the general design of the exterior of the aircraft as it would not have exhibited quite the large nacelles as those found on contemporary systems. Additionally, keeping the engine within the fuselage added some element of protection to the units as the fuselage was generally the most well-protected part of any aircraft, able to sustain large amounts of damage before losing integrity. The smaller nacelles also provided for better side visibility over the engines themselves, an issue apparent in the design of the Ar 240, that aircraft sporting its large wing-mounted engines to either side of the cockpit. A standard landing gear system was envisioned with the main gears recessing into each nacelle and a retractable tail wheel operating under the rearward portion of the fuselage. The tail section was dominated by a very distinguishable arrangement featuring a high-mounted tailplane with a protruding appendage - an interesting design approach even for this time.
The cockpit was of a glazed variety, again following the lead of the Ar 240 before it. The seating area was held well-forward in the fuselage providing exceptional views outward, above and down. The pilot sat extreme forward with the gunner seated directly behind in a back-to-back seating arrangement. The gunner would have operated the rear-ward facing machine guns through a periscope system.
At the heart of any heavy fighter was its offensive armament and the E.654 did not disappoint. A battery of 6 x Mk 103 series 30mm heavy cannons was arranged in groups of three in bulges on either side of the lower fuselage. Defensively, the E.654 utilized a system similar to the Arado Ar 240 aircraft - with the rear gunner controlling a dorsal and ventral turret (each fitted with 2 x MG 131 series 13mm heavy machine guns) in recessed positions near the base top and bottom positions of the empennage.
In all respects, the E.654 would have been a serviceable aircraft but the complexity inherent in the engine layout and operation doomed the type to the drawing board - similar to the fate that fell the E.561 proposal. Getting materials and parts for such a complex system proved too much for Luftwaffe technicians to address - especially when one considers the defensive war Germany was becoming embroiled in. It seems that the multi-shaft arrangement of the E.654's design would have developed other engineering obstacles as well with most of the issues no doubt related to potential vibration caused by the engine and shaft layout and maintaining the proper level of power generated at the engine, which would then have to be translated through the shaft and eventually to the propeller.
The E.654 received an internal project name of "Skorpion", no doubt due to the stinger-like protrusion at the top of the tail fin. It was also known by the descriptive name of "Kampfzerstorer". Arado designer Walter Blume headed up the project.