The number of improvements found in the various types of the Do-217 appear
to make this aircraft a profitable subject for further comment in view of its many
diverse uses as a long range heavy bomber, minelayer, and reconnaissance airplane.
The armament of the 217-E usually consists of one 20-mm Oerlikon cannon
or a 13-mm machine gun on a free mount in the nose, one 15-mm machine gun fixed
in the bottom of the nose, firing forward, one 13-mm machine gun in an
electrically-operated dorsal turret, a 13-mm machine gun on a free mount in the ventral position,
and two 7.9-mm machine guns on free lateral mounts. In a recently crashed airplane,
two sets of twin 7.9-mm machine guns were found. It is believed that they are now
being used for lateral protection instead of single machine guns of the same caliber.
The most recent change found in Do-217 armament is the addition of three fixed,
rearward-firing guns. One is in the extreme tail and one is in the aft end of each
engine nacelle. A master switch and a cocking switch are provided for the pilot
and there are three firing buttons, one each for the pilot, dorsal gunner, and ventral
gunner. The circuits would allow the firing of either 7.9-mm or 13-mm machine
guns. It is possible that a 30-mm gun will be fitted on a few of these aircraft for
use as tank-busters. The night-fighter version of the Do-217 has four 20-mm
fixed cannon in the nose in addition to four 7.9-mm machine guns. It has been
reported that an experimental model is now being developed which will carry eight
cannon and four machine guns.
The engines are the usual BMW 801A 14-cylinder, twin-row, air-cooled
radials, each being easily detachable from the aircraft, and apparently now
equipped with a modified exhaust system.
Six fuel tanks having a total capacity of 785 U.S. gallons are mounted in the
wings. Two fuel tanks with a total capacity of 399 U.S. gallons can also be carried
in the fuselage bomb compartment instead of bombs and two 238 U.S. gallon
jettisonable tanks on the bomb-racks outboard of the engine nacelles. This gives
a maximum total capacity of 1,660 U.S. gallons, and a range of 2,445 miles at
economical cruising speed with an endurance of 11.7 hours. The large fuselage fuel
tank on the E-4 sub-type consists of a metal shell covered with self-sealing material,
the first metal shell tank to be seen in a bomber.
The aircraft has a normal bomb load of 4,400 pounds, and a maximum of
6,600 pounds. Normal stowage consists of either four 1,100 pound and four 110 pound
internal bombs or two 2,200 pound internal and two 550 pound external bombs. There
is also provision for carrying torpedoes, but the Do-217 is not frequently used as
a torpedo bomber.
The armor on the Do-217 E is reasonably comprehensive. The pilot's seat
is protected by 5-mm (.197 in) plate, the back of which is attached to an 8.5-mm
(.33 in) plate back-shield which moves it so that the pilot is always protected at any
position of seat elevation. A piece of 9-mm (.354 in) plate in the roof of the cockpit,
slightly aft of the pilot's head, gives him protection from above. For protection
of the dorsal gunner, the top of the fuselage aft of the turret is armored with two
6-mm (.236 in) plates, on either side of which is a 6-mm curved triangular-shaped
piece extending down over the sides of the fuselage. The rise of the turret above
the fuselage is protected by a 9-mm (.354 in) circular plate made in four sections
and about 12 inches high. The ventral gunner is protected in front by a 10-mm
(.394 in) vertical plate, cut away for operation of the gun, and from below by 5-mm
(.197 in) plates. One report states that he is also protected by an 8.5-mm (.335 in)
semi-circular bulkhead 3 feet 9 inches by 1 foot 8 inches, placed aft of his position.
There is no known protection for the lateral gunner. It has been reported that a
6-mm (.236 in) semi-circular bulkhead is fitted into the engine nacelles to protect
the lower half of the engine and its accessories. The dinghy recess in the top of
the fuselage about in line with the trailing edge of the wing, is armored with 8-mm
(.315 in) rear plate, 4-mm (.157 in) plate on the sides and bottom, and 5-mm (.187
in) plate on the cover.
Some of the aircraft examined were wired and equipped for electrically
operated dive-brakes, and an automatic pull-out device. The umbrella type
dive-brake in the tail of early Do-217's proved unsatisfactory and the newer models
have a five-slat type brake installed under the wing outboard of the engine nacelle,
nearer the leading edge than the trailing edge of the wing.
In addition to the large dinghy, which is omitted in later models, each of
the crew of four is provided with a single-seat dinghy, carried with their parachutes.
The F-Gerät radio altimeter, a device for measuring by radio the actual
height of the aircraft above the ground, has been found in some aircraft. Usually
a knife-edge cable-cutter is fitted, faired into the leading edge of the wing and
around the nose.