The Dornier Do 335 is one of Germany’s most weird and wonderful late WWII aircraft. Its unique push-pull engine configuration made the Do 335 extremely fast, but it also meant the aircraft was unreliable and exceedingly complex. Although it was advanced, production delays meant only a handful were made, none of which made an impact on the outcome of the war.
When the war ended the US ended up with two Do 335s, but after being studied they had little use as piston engine fighters were approaching the end of the road. Today, just one example survives.
Claudius Dornier first toyed with unconventional engine configurations in WWI, designing aircraft with propellers remotely rotated by the engine. The advantage of this configuration is a reduction in drag, as the engine can be neatly tucked away somewhere within the aircraft, only leaving the propeller exposed to the oncoming air.
In the 1930s he began investigating the idea of using two engines mounted within the fuselage – one powering a propeller at the rear and a second powering a propeller in the nose. This configuration, known as push-pull, has a number of benefits. Mounting engines on the wings, as is normally done on multi-engine aircraft, creates a lot of drag that slightly offsets the benefits of using two engines.
A push-pull layout means an aircraft has the power of a twin-engine aircraft without any increase in drag. In addition, storing both engines in the fuselage improves an aircraft’s handling and makes it easier to fly if one engine is lost.
In 1940 the project was canceled by Hermann Göring, but Dornier started working on it again in May 1942 to fulfill a request for a fast bomber-intruder. Later in 1942, the request for a bomber-intruder was changed to a multi-role fighter, so the aircraft was delayed significantly while Dornier made the appropriate modifications.
Over a year later the aircraft – now the Do 335 – first took flight. Over its relatively extensive (for late war German prototypes) testing, it was soon found to be an extremely fast aircraft, reaching 474 mph in level flight. Even on one engine, it could reach around 350 mph.
Armament came in the form of one 30 mm cannon firing through the propeller and two 15 mm cannons above the nose.
It entered production in 1944 and was given maximum priority, but by the time the war ended less than 50 had been completed.
Unique features
Many aspects of the Do 335 are unique, almost all of which are a result of its unique engine layout.
Power comes from two 44.5 liter Daimler-Benz DB 603 engines, each producing 1,800 hp. These engines allowed the Do 335 to reach high speeds, but the rear engine sometimes suffered from overheating issues. Additionally, at nearly 1 ton apiece, the engines contributed to the aircraft’s overall large proportions.
In fact for a fighter the Do 335 was monstrous. With a wingspan of 13.8 m (45 ft 3 in) and a length of 13.85 m (45 ft 5 in), it dwarfed conventional aircraft in the same role.
With two propellers – one at each end – the Do 335 faced some unique problems. One of these was with keeping both the propellers off the ground. With a propeller at the rear, it could not be a typical tail-dragger and instead sat on tricycle landing gear (one of the first aircraft to use this). The immense weight pushing down on the long and thin landing gear proved to be a problem throughout the Do 335’s short life.
Also, the rear propeller was a terrifying danger to a pilot if they needed to bail out, so the Do 335 was one of the first aircraft to come with an ejection seat.
Fate
In the air, the Do 335 was a very high-performing aircraft, able to speed away from most Allied aircraft. When it wasn’t suffering from issues with the engines or landing gear it was reportedly an excellent and gentle aircraft to fly, with brilliant acceleration and no sudden and hard-to-handle characteristics.
Some pre-production aircraft reached pilots before the war ended, but only a single production Do 335 was ever completed.
An early model was shipped to the US after the war ended, and was examined until 1948. As the jet age was gaining momentum there was little to learn from the Do 335. Dornier restored the aircraft in 1975, and it was eventually returned to the US.