During World War II, the Arado Ar 231 emerged as a lightweight floatplane designed by Arado to serve as a scout aircraft for submarines.
However, due to the requirement of being stored within the submarines, certain design compromises were made, rendering this single-seat seaplane of limited practicality.
The Ar 231, a light parasol-wing aircraft, was specifically designed for use on U-boat “cruisers” such as the Type XI B.
It was equipped with a 119 kW (160 hp) Hirth HM 501 inline engine and weighed approximately 1,000 kg (2,200 lb).
With a wingspan of 10 m (33 ft), the aircraft was ingeniously designed to fit into a storage cylinder measuring only 2 m (6 ft 7 in) in diameter.
To facilitate storage, the Ar 231’s wings had detachable sections that could be removed by two operators in under six minutes.
An interesting feature of this aircraft was its offset wing design, where the right-wing root attached to the wing’s tilted centre section (positioned above the fuselage, as seen in all parasol-wing designs) and was lower than the left-wing root.
This allowed the wings to overlap when folded, minimising the space required for storage.
The Ar 231s were found to be delicate, lacking in power, and challenging to manoeuvre, even in peaceful weather conditions, as testing soon demonstrated.
Additionally, U-boat commanders were hesitant to remain on the surface for launching and retrieval purposes.
Consequently, the development of the Ar 231s was abandoned in favour of the Focke Achgelis Fa 330 Gyroglider.
A portion of the testing was conducted aboard the auxiliary cruiser Stier, with two out of the six prototypes being taken on a single voyage.
Specifications
Crew
1
Length
7.81 m (25 ft 7 in)
Wingspan
10.18 m (33 ft 5 in)
Height
3.12 m (10 ft 3 in)
Wing area
15.2 m2 (164 sq ft)
Empty weight
833 kg (1,836 lb)
Gross weight
1,050 kg (2,315 lb)
Powerplant
1 × Hirth HM 501,
6-cylinder air cooled inverted inline piston engine,
120 kW (160 hp)
Propellers
2 bladed fixed pitch propeller
Performance
Maximum speed
170 km/h (110 mph, 92 kn)
Cruise speed
130 km/h (81 mph, 70 kn)
Range
500 km (310 mi, 270 nmi)
Endurance
4 hours
Service ceiling
3,000 m (9,800 ft)
Wing loading
69.1 kg/m2 (14.2 lb/sq ft)
Power/mass
0.113 kW/kg (0.069 hp/lb).
Sources Arado Geschichte Eines Flugzeugwerks-Jorg Armin Kranzhoff. Aircraft of the Luftwaffe 1935-1945, An Illustrated Guide-Jean-Denis GG LaPage. The Official Monogram Painting Guide to German Aircraft, 1935-1945-Kenneth A Merrick & Thomas H Hitchcock. Sea Eagles, Luftwaffe Anti Shipping Units, 1939-1941, Vol 1-Chris Goss.
