The Aviation Historian — January 2018

26 THE AVIATION HISTORIAN Issue No 22

10, 1944, Wg Cdr G.E.F. Proctor of AI2(g)
describes the system and its origins. This report
goes into surprising detail on the development
of the Ar 232, describing how the first example
was damaged on take-off owing to its Fowler
flaps being ineffective. The second aircraft was
being modified “to install an ‘Absaugklappe’
(suction flap) as a safeguard against breakaway
of the airflow”. The system used a flap installed
on the upper surface of the wings near the
fuselage. When opened, air was sucked into
“a special chamber from where, suitably
compressed, it flows over the upper surface of
the outer part of the wing with greatly increased
speed”. The report also stated that the Arado “is
reported to take-off in under 200yd (presumably
with a light load)”.
A further report, P.5/8546, dated November
27, 1943, describes how the Absaugklappe
was a two-part affair, with an inboard flap and
“an outer part which is lowered together with
the aileron”. Within days, more information
materalised. Report P.5/8750 of November 30,
1943, states that “The ‘Absaugklappe’ fitted to
this aircraft has yielded excellent results, and,
together with a special arrangement of the
undercarriage, is said to have limited the take-off
run to 60m [197ft]”. A take-off run of less than
200ft is most impressive; indeed, this was in the
same league as the Fieseler Fi 156 Storch, a type
whose loaded all-up weight was ten per cent of
the Arado’s empty weight.

On January 13, 1945, Wg Cdr Proctor issued

AI Report 2296, which included all the available

information on the Ar 232 and was supported

by a highly accurate drawing of the four-

engined aircraft in landing configuration. The

report describes how the Arado operated on the

ground and noted its “unusual undercarriage

arrangement” and how its mainwheels could be

“partially retracted while it is still taxying”, to

ensure that “it is in the most convenient attitude

for unloading and loading at the moment when

it comes to rest”. Proctor also observed that the

main undercarriage was probably fully extended

for take-off to reduce rolling resistance.

The most striking aspect of this whole exercise

is the quantity and quality of the intelligence

the Allies had. The brave Poles and Norwegians

who provided information of a highly technical

nature played a key role in the process. This

was particularly true of the Polish engineer in

the factory who furnished drawings of the key

features, such as the Absaugklappe and the

undercarriage, not to mention the progress of

the development. The PIs at RAF Medmenham

had identified a new type but could not provide

more than key features; dimensions, possible

configuration and undercarriage arrangement

gleaned from aerial photography. Once the Air

Intelligence officers realised that the photo- and

human intelligence (photint and humint in

ABOVE The strikingly accurate artist’s impression of the four-engined Ar 232B drawn by Peter Endsleigh Castle,
whose work later became well-known through his regular contributions to RAF Flying Review and other aviation
magazines from the 1950s onwards. Castle joined MI6’s Air Intelligence Branch as a 21-year-old in May 1939.

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