Hybrid Aircraft - Heinkel He.111Z
Germany had designed two heavy cargo gliders in 1940, the Me.321 and the Ju.322,
the Luftwaffe had no suitable aircraft to tow them. The troika-schlepp, or triple-tow,
using three Messerschmitt Bf.110C-1s, proved dangerous, and types such as the
Junkers Ju.90 lacked the power required for the task. Ernst Udet conceived the
idea of joining two bombers by a common central wing section, and urged the Junkers
company to develop such a type.
In 1941, two prototypes of the He.111Z (Zwilling, or "twin") were produced.
Two He.111H-6 bomber fuselages with complete tail assemblies were joined by a
new centre section wing having three Jumo engines (giving a total of five engines).
Despite its rapid development, after testing late in 1941, and some airframe strengthening,
the He.111Z proved to be an efficient glider tug, with more than enough power
to tow the new giant gliders.
could be assisted by two 1,100 lb. thrust (500 kgp) JATO rockets beneath each
fuselage and two 3,307 lb. thrust (1500 kgp) rockets under the centre section,
one each side of the middle engine. For the large Me.321 glider, the towing cable
was divided, and fixed at each central wing-root, joining between the tailplanes
into a single 16 mm cable. Smaller gliders, such as the Go.242, could be towed
in pairs on independent cables attached to each fuselage of the He.111Z.
A single He.111Z was able to tow three small gliders during trials, but this was
not standard practice.
The He.111Z entered production early in 1942 and were placed in service that year.
Only the prototypes and the first few production models used He.111H-6 airframes;
the remainder were based on the He.111H-16. They were very successful, and well-liked
by the crews.
The He.111Z carried a crew of seven. The pilot sat in the port fuselage, with
five throttles, full instrumentation, and controls for the undercarriage members
and radiator flaps for the gear and three engines on his side. The second pilot
in the starboard fuselage was given dual controls but no throttles, and worked
the starboard undercarriage and two sets of starboard engine radiator flaps. The
second pilot also served as navigator. A mechanic, radio operator and gunner were
housed in the port fuselage, and a mechanic and gunner in the starboard.
Normal armament consisted of a 20 mm MG FF cannon in the starboard nose position
and an MG 15 in the port nose. Each fuselage had a single 13 mm MG 131 in the
dorsal position and a single 7.9 mm MG 15 in the rear of the ventral position
and a similar weapon in a beam hatch of each fuselage. Various other armament
configurations were tried, including four 13 mm MG 131s, two MG 91Z paired 7.9
mm installations, and five single MG 81J guns.
The He.111Z was not easy to control in flight, but it enjoyed a trouble-free career.
Only three months had elapsed between the prototypes' first flights and delivery
into service, with only a couple of days dedicated to service evaluation. It could
maintain level flight with three engines cut, provided the remaining two provided
Eight of the twelve He.111Zs were destroyed in service, being shot down by fighters
or destroyed as a result of bombing. The remaining four were presumably destroyed
He.111Z 'Zwilling' data:
Five Junkers Jumo 211F-2/S-2 engines.
JATO rockets could be used
one below each fuselage and one each
side of the central engine.
EMPTY EQUIPPED WEIGHT:
47,400 lb. (21500 kg)
63,052 lb. (28600 kg)
116 ft. 1.66 in. (35.4 m)
55 ft. 9.66 in. (16.4 m.)
1,587.06 sq. ft. (148 m²)
|DISTANCE BETWEEN FUSELAGE
41 ft. 11.75 in. (12.8 m.)
TOWING SPEED (2x Go.242):
155 mph (250 km/h)
TOWING SPEED (1x Me.321):
137 mph (220 km/h)
264-270 mph (425-435 km/h)
In excess of 32,800 ft. (10000 m.)
OPTIMAL CRUISING ALTITUDE:
9,030 ft. (5800 m.)