Submarines and their Weapons - Aircraft of World War II

HYBRID AND COMPOSITE AIRCRAFT
Engineers on both sides during World War II gave
considerable thought to the problems associated with
guiding unmanned explosives-packed aircraft to a target.
We shall see in Chapter Five how the USAAF
used remotely controlled B-17s to complete the
destruction of V weapons sites in France in 1944, but
long before that, in 1940, the RLM had turned the
problem over to DPS. The parameters the Institute
was given included supporting parasite fighter aircraft
and refuelling heavily loaded bombers in flight as
well as guiding a flying bomb to its target zone, and
the first tentative solution was to tow one aircraft with
another using either a flexible cable or a semi-rigid
bar which could contain or support a fuel hose. There
was a persistent belief that such a system had merit,
and experiments with it continued until 1945, but by
late 1941, one of the Institute's teams had begun to
work on a means of mounting one aircraft on another,
piggyback-style, and in January 1942 the 'Mistel'
('Mistletoe') concept received official approval.
Soon, Junkers and autopilot-maker Patin were
ordered to collaborate with DPS, and within little over
a year, work had begun on assembling a prototype
combination of Ju 88A-4 and Bf 109F-1.
'MISTEL' 1
DFS's first task had been to devise a suitable structure
to co-locate the two aircraft so that the stresses acting
on them would be transmitted between the two main
spars, with coupling links which could be sundered
either mechanically or explosively. The result was a
pair of tripod struts, the apex of which hooked into
plates on the underside of the Bf 109's wing roots, the
HYBRID AIRCRAFT AND GLIDERS
two outer bases of each located on load-bearing plates
which traversed the main spar, while the inner legs
located on to it directly through the fuselage top. A
single pole supported the Messerschmitt's tail and
kept the fuselage axes parallel. In later combinations,
the fighter sat at a 15-degree nose-down angle.
The steering and control system was located in the
rear of the Junker's fuselage and consisted of a master
compass, a steering compass and a three-axis
autopilot from Patin. This apparatus was used to steer
the combination in normal flight via servos and two
simple thumb switches in the fighter's cockpit, one
for rudder and ailerons, the other for elevators, with
the fighter's controls remaining free. However, the
two aircraft's control systems could be linked, and
thus operated from the fighter by the usual combination
of stick and pedals (via servos, once again), at
will. Either the bomber's two engines alone, or all
three, could be used, depending on the speed and
range required, all fuel being supplied from the host
aircraft. This was by no means the only modification
needed to the bomber component - in fact, the aircraft
were virtually gutted and rebuilt - but the amount of
work needed on the fighter was minimal. In order to
accommodate the explosive 'warhead', the existing Ju
88 nose section, including the glazed cupola which
formed the cockpit cover, was removed entirely, and a
solid bulkhead built up. The 3500kg (7720lb) hollow
charge, with its distinctive proboscis-like extension
Below: One of the earliest'Mistel' combinations (they
were known unofficially as 'Vater und Sohn' - father and
son) matched the Messerschmitt Bf 109F with the Junkers
Ju 88A-4. Testing began in July 1943.