Twitter
Facebook
From well before World War II, the German aircraft designer Claudius Dornier had been interested in tandem engines.
He felt the traditional system of placing one engine on each wing reduced performance and that the engines in tandem in the fuselage would make the aircraft, in effect, a single engine one.
The most important advantage of this arrangement was the reduction of frontal area drag to that of a single-engine design, allowing for higher performance. It also kept the weight of the twin power plants near the aircraft center line, increasing the roll rate compared to a traditional twin engine aircraft. Finally, with tandem engines, a single engine failure would not lead to asymmetric thrust, so the plane is easy to handle with one engine out.
Dornier used tandem engines on his 1930s multi-engine flying boats, and with the beginning of World War II in 1939, Dornier began work on a high speed bomber project with a tandem engine layout.
However, work on the bomber was stopped in early 1940 when Hermann Göring ordered the cancellation of all projects that would not be completed within a year — one of the most unfortunate long range decisions made by the Germans in World War II and one that cost them their technological lead in many areas.
By 1942, new projects were authorized and in May 1942, Dornier submitted an updated version of his high speed bomber and was awarded development contract under the designation Do 335.
Then, in autumn 1942, Dornier was told the high speed bomber was no longer required but to develop a multi-role fighter based on the Do 335 layout.
The resulting aircraft was huge for a fighter — as long as a Ju-88 bomber — and was very heavy — 21,000 pounds fully loaded. It sat on high, stalky tricycle landing gear with a low mounted, stubby broad wing set well back that gave the pilot excellent downward visibility.
The Do 335 was powered by two massive, tandem DB 603A engines each delivering 1,300 horsepower, one mounted conventionally in the front behind an annular ring cowling, and the second behind the wing cooled by a large air scoop under the fuselage. It had a set of cruciform tail surfaces so the ventral vertical fin–rudder protected the rear propeller from striking the ground on takeoff or landing.
The design incorporated several other unique features, including a reversible-pitch forward airscrew to shorten what was expected to be a long landing run, hydraulically operated flaps, an inclined seat like the F-16 with a compressed air powered ejection seat, needed to clear the rear propeller in the event the pilot had to bail-out (although the vertical tail and propeller could be jettisoned by explosive bolts).
For armament, the first models were fitted with a 30 millimeter engine mounted MK103 cannon and two 15 millimeter MG151 cannons in the upper nose.
The long, slender fuselage, relatively small wings and cruciform tail led Dornier to name the Do 335 the “Pfiel,” or Arrow, but the very long nose led the test pilots to informally name it the “Ameisenbär,” or Anteater.
The prototype flew on Oct. 26, 1943, and the first flights showed the concept was sound.
As the tests progressed, the aircraft showed very high speed and acceleration, excellent general handling, and a reasonable turning circle, much superior to a normal twin engine fighter. Although some snaking and porpoiseing was found at high speeds and it had very poor rearward vision and weak undercarriage, these were considered minor problems.
The Luftwaffe air inspector, Field Marshal Erhard Milch, who was in charge of aircraft production, said the Do 335 could “hold its own in speed and altitude with the latest Allied fighters and does not suffer from engine reliability issues (like the German jet fighters).”
Its performance was so good that on May 23, 1944, with an Allied invasion of France expected at any time, Hitler ordered maximum priority be given to the Do 335 in what was called the “Emergency Fighter Program.”
The first 10 Do 335s were used by a special group formed in September 1944 for the service evaluation and development of operational tactics. In action, it showed a maximum speed of 474 mph at 21,000 feet and it could easily outrun any Allied fighters it encountered.
But Allied bombing destroyed the main factory and, because the Do 335 were complex aircraft to build — installation of the electronics alone took 60 hours of assembly — it arrived late to the operational units. This, and the lack of aviation fuel, meant the operational career of the Do 335 was limited.
Of all the late war German developments, the Do 335 was one of the few that really suffered from political delays rather than lack of technology.
With proper decisions, the innovative aircraft probably could have been in active service in early 1944, in time to cause great damage to Allied bomber forces.
A very promising two-seat night interceptor with a second cockpit for the radar operator, the FuG217 radar and flame dampers fitted to the exhausts was almost completed. Another promising varient was the more heavily armed B-series heavy fighter with the two 15 millimeter cannons in the nose replaced by 20 millimeter MG151s and two 30 millimeter MK103 cannons mounted on the inner wing leading edges, which would have made it a devastating day bomber interceptor.
Two of the surviving single seaters were shipped back to the U.S. for detailed evaluation by the U.S. Navy and U.S. Army Air Force. After Navy flight tests from 1945 to 1948, one aircraft was donated to the Smithsonian’s National Air Museum.
In 1975, this aircraft was restored by Dornier employees, many of whom had worked on the airplane originally.
Today, it is on display at Steven F. Udvar-Hazy Center near Washington Dulles International Airport.
(For questions or comments, contact Dr. Michel at marshall.michel@spangdahlem.af.mil.)
