Dornier Do 335 Pfeil
No-one can accuse the
World War II German aircraft designers of conservatism and, while the
majority of combat aircraft were of conventional design, there were
many others which pushed the forefront of aeronautics. Unhampered by
tradition, German designers sought fresh means to solve old problems,
and in so doing provided the Allies in both East and West with a wealth
of advanced research material following the end of hostilities. One of
the most famous of the bizarre shapes which took to the air over
Germany was the Dornier Do 335 Pfeil, a brave attempt to provide the
Luftwaffe with a potent fighter-bomber, night-fighter and
A Do 335A-1 serving with Erprobungskommando 335 (The only
semi-operational unit with this aircraft)
Prof Dr Claudius
Dornier was the genius behind the famous company of Dornier-Werke GmbH,
and he had established a long line of successful aircraft, notably in
the field of flying-boats. For most of the late 1930s and World War II,
Dornier was primarily concerned with the production of bombers for the
Luftwaffe. Since the end of World War I, Claudius Dornier had been
interested in the field of centreline thrust, whereby two engines
shared the same thrust line (one pulling and one pushing). Benefits of
this system were obvious over a conventional twin layout, with only the
same frontal area as a single-engined aircraft, the wing left clean of
engine nacelles and attendant structures, and no asymmetric pull if one
engine cut out. However, problems did exist in the area of the drive
shaft which drove the rear propeller. The unconventional tandem engine
layout was patented by Claudius Dornier in 1937.
flying-boat experience gave him a wealth of knowledge in simple
centreline thrust arrangements, where two engines were mounted
back-to-back over the centreline of many of his designs. By the
mid-1930s, he saw the possibility of using this concept to power a
high-speed fighter, but first the rear engine extension shaft
arrangement had to be proved. To that end Ulrich Hutter was
commissioned to design a small testbed for the arrangement. Designated
the Goppingen Go 9, and built by Schempp-Hirth, the testbed featured a
pencil-slim fuselage contained a 80 hp (59.6 kW) Hirth HM 60R engine
mounted at the centre of gravity beneath the shoulder-set wing. Stalky
main undercarriage units retracted into the wing, while a nosewheel
unit retracted forward into the extreme nose. Behind the wing a long
and slender tail boom hid the drive shaft, which extended past a
cruciform tail to a four-bladed wooden propeller.
Flying for the first
time in 1940, the Go 9 proved that the rear pusher principle was both
efficient and safe, which gave Dornier new impetus to his fighter
designs taking shape on the drawing boards. However, the Technische Amt
of the RLM decreed that Dornier abandon his work with fighters and
return to the main job in hand of producing bombers and flying-boats,
despite some initial interest in his radical designs. Nevertheless, in
1942 the Technische Amt issued a requirement for a high speed unarmed
intruder aircraft, and Dornier submitted his Projekt 231 design,
incorporating the tractor-pusher engine arrangement. After evaluation
Dornier was awarded a development contract in the face of opposition
from Arado and Junkers, and the designation Do 335 was assigned to
As design got underway,
the RLM issued a new directive to redesign the Do 335 as a
multi-purpose day fighter, night-fighter, fighter-bomber, Zerstorer and
reconnaissance platform, which caused a delay in production of the
prototype. By the autumn of 1943 the Do 335 was ready for flight.
Dornier's concept had
emerged as a fearsome looking aircraft, appearing as purposeful as a
fighter could. In the forward fuselage a Daimler-Benz DB 603 featured
an annular-ring cowl, while exhaust stubs just aft of the trailing edge
belied the position of the rear engine. Underneath the rear fuselage a
large air scoop aspirated the second unit, which powered a three-bladed
propeller mounted behind a cruciform tail. Under the centre-section of
the wing were doors for a small weapons bay, capable of carrying a
single 1,100 lbs (500 kg) or two 550 lbs (250 kg) bombs. The
undercarriage was a tricycle arrangement, with the wide-track main
units retracting inwards into the wing and the nosewheel retracting
backwards (following a 90 degree rotation) into the area beneath the
The broad wing was set
well back, and although the name Pfeil was used semi-officially, the
service pilots who became acquainted with this extraordinary machine
soon dubbed it Ameisenbär' (ant-eater), thanks to its long nose. A
Dornier pilot was at the controls for the first flight from
Oberpfaffenhofen, this taking place on 26 October 1943 with the Do 335
V1 first prototype (CP+UA). After initial Dornier trials, it moved to
Rechlin to begin extensive official trials. Reports from
Oberpfaffenhofen and Rechlin were favourable, with only slight
longitudinal stability problems encountered. Most pilots were surprised
at the speed, acceleration, turning circle and general handling of the
type, and development continued smoothly. Further prototypes joined
Dornier and Rechlin trials, introducing new improvements such as
redesigned undercarriage doors and blisters in the canopy accommodating
mirrors for improved rearward vision.
By the fifth prototype
armament had been installed, this comprising two 15 mm MG 151 cannon in
the upper fuselage decking and a single 30 mm MK 103 cannon firing
through the forward propeller hub. Subsequent prototypes were used for
further flight trials and engine tests, culminating in the Do 335 V9
built to pre-production standards. The first Do 335A-O pre-production
aircraft (VG+PG) followed shortly in mid-1944, with full armament and
ready to start operational evaluation. The Erprobungskommando 335 was
established in September 1944 to conduct tactical development using
many of the 10 Do 335A-0s built. Service trials began with the V9 with
the Versuchsverband des Oberfehlshabers des Luftwaffe.
By late autumn in 1944,
the Do 335A-l full production model appeared at Oberpfaffenhofen, this
introducing the definitive 1,800 hp (1342 kW) 12-cylinder DB 603E-1
engine and two underwing hardpoints capable of carrying fuel or 550 lbs
(250 kg) bombs. Similar in airframe details to the Do 335A-1 was the Do
335A-4 (T9+ZH) unarmed reconnaissance version. Only one was completed,
adapted from a Do 335A-0 with two Rb 50/18 cameras in the weapons bay
and increased external fuel. Daimler-Benz DB 1,900 hp (1417 kW) DB 603G
engines were to have been fitted with higher compression ratio and more
powerful superchargers. The sole example was later tested at 1./Versuchsverband
Next in line of the
Pfeil variants was the Do 335A-6 (prototype Do 335 V10), which was the
night fighter variant. Armament remained unchanged from the fighter
bomber, but FuG 220 Lichtenstein SN-2 or Fug 217J Neptune/FuG 218
Neptun V airborne intercept radar was to have been incorporated, the
aerials being located forward of the wing (lateral beam port and
vertical beam starboard). To operate the radar a second crewman was
needed, and to accommodate him a cockpit was incorporated above and
behind the pilot. Giving the Pfeil an even stranger appearance than
before, the second cockpit also meant a considerable restructuring of
the fuel system since fuel capacity was reduced to 600 litres. To
augment this the weapons bay area was converted over to fuel storage.
The negative effect on performance of the extra cockpit, aerials,
weight and other modifications such as flame damping tubes over the
exhaust ports was in the region of 10 percent, but production aircraft
would have offset this partially by being fitted with DB 603E engines
with MW-50 (water/methanol) boost instead of the DB 603A retained by
the sole example. Production was scheduled to have been undertaken by
Heinkel in Vienna, but this plan was overtaken by events and the
tooling was never assembled. There was only one operational Do 335A-6,
flown by Werner Baake in I./NJG 3 flying Do 335 V-10 (CP+UK) with FuG
220 Lichtenstein SN-2 radar.
The final pair of Do
355A variants comprised the Do 335A-10 and Do 335A-12, both featuring
the second cockpit for use as conversion trainers. The former was
powered by the DB 603A engine (prototype Do 335 V11) and the latter by
the DB 603E (prototype Do 335 V12). With full controls in the raised
cockpit for the instructor, the two prototypes were both delivered
without armament, but this was rectified in the pair of Do 335A-12
After development of
fighter-bomber, reconnaissance, trainer and night-fighter variants, the
role of heavy Zerstörer was next to be developed, as a direct
result of the worsening war situation. During the winter of 1944/45,
the Do 335 V13 (RP+UP) emerged from the Oberpfaffenhofen factory as the
Do 335B-1. This aircraft featured the replacement of the weapons bay by
a fuel tank, and the replacement of the 15 mm cannon by 20 mm MG 151
cannon. More heavily armed was the Do 335 V14 (RP+UQ) which, intended
for service as the Do 335B-2, featured the same armament and an added
MK 103 30-mm cannon mounted in the wings.
In the event, these
were the only B-series aircraft to be completed, although others (V15
to V20) were on the construction line at the termination of the
project. These included more B-l and B-2 prototypes, and a pair of Do
335B-6 prototypes, these being night-fighters similar to the Do 335A-6
but with the heavy armament of the Do 335E-l. Other prototypes would
have featured DE 603LA engines with a two-stage supercharger. The Do
335B-3 was to be powered by two 2,100 hp (1566 kW) Daimler-Benz DB
6O3LA engines. One other development deserves mention, the B-4, B-5 and
B-8 models which featured a 14 ft 10 in (4.3 m) increase in wing span
for greater altitude performance. The development of these new outer
wing panels had been undertaken by Heinkel, but they remained on the
drawing board. The last flight took place on 20 April 1945, when
Hans-Werner Lerche took Do 335A-02 from Rechlin to Oberpfaffenhofen.
included the Do 435 night-fighter, with side-by-side seating, cabin
pressurisation and long-span wooden wings, the Do 535 mixed-powerplant
fighter with the rear DB 603 replaced by a jet engine, and the Do 635
long-range reconnaissance platform which aimed to mate two Do 335
fuselages together with a new centre-section. When the Allies overran
the Dornier factory at Oberpfaffenhofen in late April 1945, some 37
Pfeils had been completed, with about 70 others awaiting final assembly
and the arrival of components.
As far as is known, the
Pfeil never entered into combat, although US pilots reported seeing the
strange aircraft in the sky during sorties over Germany, and the
Erprobungskommando was forced to send aircraft into a sky which could
not be guaranteed as being free of hostile aircraft. In its single-seat
version it was one of the fastest piston-engined fighters ever built,
with a claimed top speed of around 475 mph (765 km/h). Despite this
high performance, it was the much slower two-seat night-fighter version
which would probably have proved the most effective if the war had
continued. Equipped with excellent radar and powerful weapons, and
blessed with good visibility, combat persistence and performance, the
night-fighter would have wreaked havoc against the RAF bomber streams.
Flying the Pfeil was an
experience, thanks to its high performance and unusual configuration.
While the performance provided an exhilarating ride for the pilot, the
configuration prompted some doubts. His main concern was the ejection
seat, the Do 335 being only the second production type to feature this
(after the Saab J21). Before firing the seat, explosive bolts which
held the upper vertical tail surface and rear propeller were fired to
clear a way for the egressing pilot. Despite the ejection seat, he had
to jettison the canopy manually. As another safety feature, the lower
vertical tail surface was jettisonable in case a wheels-up landing was
To conclude, the Pfeil
proved to be a sound design with no major faults. If development had
been allowed to continue at a steady pace, and had sufficient resources
been made available, the teething problems which remained with the type
could have been ironed out, and the Pfeil could have emerged as a
warplane of major importance to the Luftwaffe. However, as the military
situation facing Germany darkened during 1944/45, resources continued
to be split between dozens of projects, and development of the Do 335
was rushed, to compensate for the dislocation wrought by allied bombing
and the advance of the Allied armies, Development and production was
also delayed by the state of German industry, which could not provide
the necessary sub-contracted components such as propellers, engines and
radios. The development effort was further diluted by unnecessary
effort on unattainable advanced derivatives while the basic
fighter-bomber was starved of both manpower and money.
Do 335 Ejection Seat
One interest of note
was that the "Pfeil" was equipped with an ejection seat. The upper
tailfin and the rear propeller were equipped with explosive bolts to
separate them from the fuselage to avoid impacting the pilot in the
case of ejection.
Do 335 Cockpit Layout
Today, the sole
remaining example of this unique type is on display at the National Air
and Space Museum in Washington DC. Do335A-0 VP+GH (Wk Nr. 240102) was
one of the two examples evaluated at the US Navy's Patuxent River Test
Centre in 1945. Thereafter, it stayed in open storage for 27 years in
the grounds of the NASM storage facility at Silver Hill. In October
1974 the decaying airframe was flown back to Munich, for a complete
restoration by Dornier Aircraft at Oberpfaffenhofen (then building
Alphajets). The magnificently restored aircraft was first displayed at
the Hanover Airshow in May 1976, and then loaned to the Deutches
Museum, Munich, for a several years before returning to the NASM.
Dornier Do P.231 Pfeil
- The original bomber designation in spite of the fact it was designed
as a fighter.
Dornier Do 335A-0/A-1
Pfeil - Do 335A-0 was the fighter bomber variant and the Do 335A-1 was
the fighter variant.
Dornier Do 335A-4 Pfeil
- A reconnaissance version with Rb 50/18 cameras.
Dornier Do 335A-6 Pfeil
- This was a night fighter version equipped with FuG 220 Lichtenstein
SN-2 or FuG 218 Neptun V radar. Only a single aircraft was produced.
Dornier Do 335A-10/A-12
Pfeil - A total of three tandem seat trainers.
Dornier Do 335B-1/B-2
Pfeil - The Do 335B-1 was fighter version with two 20 mm MG 151/20
cannon and one 30 mm MK 103 cannon but soon abandoned in favour of the
Do 335B-2. The Do335B-2 was also a fighter with three 30 mm MK 103
cannon and two 20 mm MG 151/20 cannon but only two prototypes were
Dornier Do 335B-3 - The
Do 335B-3 was to be powered by two 2,100 hp (1566 kw) Damiler-Benz DB
603LA engines. Never built.
Dornier Do 335B-4 - Was
intended to have an higher aspect ratio.
335B-5/B-6/B-7/B-8 - These the designations given to proposed night
fighter variants, but they never materialized.
Dornier Do 435 -
Proposed two seat night fighter.
Dornier Do 535 - Was to
be developed in conjunction with Heinkel with the rear piston engine
being replaced with a turbojet engine of Heinkel design.
Dornier Do 635 "Zwilling"
- Proposed long range reconnaissance aircraft created by the merging of
two airframes by the creation of a new wing centre section.
Do 335A-1 Pfeil "Arrow")
Seat Fighter Bomber
Hutter designed the original Goppingen Go 9 research aircraft and Dr
Claudius Dornier held the patent for the tandem engine layout.
Dornier-Werke GmbH (Schempp-Hirth built the Goppingen Go 9 on which the
Dornier Do 335 was based).
1,750 hp (1305 kw) Daimler-Benz DB 603A-2 12-cylinder inverted Vee
Maximum speed 478 mph (770 km/h) at 21,000 ft (6400 m); cruising speed
426 mph (685 km/h) at 23,295 ft (7100 m); service ceiling 37,400 ft
Range: 857 miles
(1380 km) on internal fuel.
16,314 lbs (7400 kg) with a maximum take-off weight of 21,164 lbs (9600
45 ft 3 1/4 in (13.80 m); length 45 ft 5 1/4 in (13.85 m); height 16 ft
4 3/4 in (5.00 m); wing area 414.42 sq ft (38.50 sq m).
(A-0/A-1) One 30 mm MK 103 cannon firing through the propeller shaft
and two cowling mounted 15 mm MG 151/15 cannons. (B-2) One 30 mm MK 103
cannon firing through the propeller shaft and two cowling mounted 15 mm
MG 151/15 cannons plus two 30 mm MK 103 in the wings. (Bomber versions)
One 1,102 lbs (500 kg) bomb or two 551 lbs (250 kg) bombs internally
and two 551 lbs (250 kg) bombs externally.
P.231 (original bomber designation), Do 335A-0 (fighter bomber), Do
335A-1 (fighter), Do 335A-4 (proposed reconnaissance variant), Do
335A-6, Do 335A-10/A-12 (tandem trainers), Do 335B-1 (fighter with two
20 mm MG 151/20 cannon), Do 335B-2 (fighter with two 30 mm MK 103
cannon), Do 335B-3 (powered by two 2,100 hp (1566 kw) DB 603LA
engines), Do 335B-4 (was intended to have an higher aspect ratio).
Corresponding night fighter variants were given the designations Do
335B-5, Do 335B-6, Do 335B-7 and Do 335B-8; Do 435, Do 535, Do 635
Fug 125a blind landing receiver and a Fug 25a IFF.
flight (Do 335V-1) autumn 1943; (production A-1) late November 1944.