POWER PLANT: One Hirth HM 502 six-cylinder inverted inline engine, rated at 160 hp
PERFORMANCE: 106 mph
COMMENT: Designed from the outset for use on U-boat “cruisers”, like the Type XI B, the Ar 231 was a light parasol-wing aircraft. The aircraft was powered by an inline engine, weighed around 2,200 lb, and had a 33ft wingspan. The design led to a simple and compact aircraft that could be fitted into a storage cylinder only 6.7 ft in diameter. For ease of storage, the Ar 231’s wings featured detachable sections that two operators could remove in less than six minutes. One unusual feature was an offset wing design, with the right wing root attaching to the wing’s tilted center section (elevated above the fuselage, as on all parasol-wing designs) and lower than the left wing root, to allow the wings to be quickly folded up. Testing soon revealed the Ar 231s to be fragile, underpowered, and difficult to fly even during calm weather, and as a result, development ended in favour of the Focke-Achgelis Fa 330 gyro glider. Some of the testing was done on the auxiliary cruiser “Stier”. Only six prototypes were built (Ref.: 24).
TYPE: Long-range Transport, Maritime Patrol and Bomber Flying Boat
ACCOMMODATION: Crew of 12
POWER PLANT: Six Daimler-Benz DB 603G, rated at 1,900 hp
PERFORMANCE: 264 mph at 19,685 ft
COMMENTS: First prototype flew in April 1944, but was sunk early 1945 by strafing Mustangs. At the end of WWII the second prototype was virtually complete and construction of the third was in an advanced stage
POWER PLANT: One BMW VI 7,3 Z liquid-cooled engine, rated at 750 hp
PERFORMANCE: 205 mph
COMMENT: The Heinkel He 51 was a single-seat biplane which was produced in a number of different versions. It was initially developed as a fighter, it was also developed as a ground-attack aircraft and a floatplane.
In 1931, Heinkel Aircraft Company developed the Heinkel He 49, officially an advanced trainer in fact it was a fighter. The first prototype flew in November 1932, and was followed by two further prototypes with a longer fuselage, and a revised engine. The type was ordered into production for the still secret Luftwaffe as Heinkel He 51, the first pre-production aircraft flying in May 1933. Deliveries started in July of the next year.
The He 51 was a conventional single-bay biplane, with all-metal construction and fabric covering. It was powered by a BMW VI engine, with an armament of two machine guns mounted above the engine. The He 51 was intended to replace the earlier Arado Ar 65, but served side-by-side with the slightly later Arado Ar 68. The He 51 was outdated the day it entered service, and after an initial run of 150 production fighters, the design was switched into the modified He 51B, with approximately 450 built, including about 46 He 51B-2 floatplanes. With begin of WW II the Heinkel He 51B-2 was only used in a role as trainer (Ref.: 24).
POWER PLANT: One BMW 132K radial engine, rated at 960 hp
PERFORMANCE: 208 mph
COMMENT: The Heinkel He 114 was a sesquiwing reconnaissance seaplane produced for the German Kriegsmarine (German Navy) in the 1930s for use from warships. It replaced the company’s Heinkel He 60, but did not remain in service long before being replaced in turn by the Arado Ar 196 as standard spotter aircraft.
While the fuselage and flotation gear of the He 114 were completely conventional, its wing arrangement was highly unusual. The upper set of wings was attached to the fuselage with a set of cabane struts, as in a parasol wing monoplane, whereas the lower set was of much lesser span while having approximately the same chord. This general layout is not especially unusual, and is known as a “Sesquiplane”, or a biplane which has a smaller lower wing. Typically, the lower wing is about 3/4 of the span of the upper wing, and has a smaller chord as well. The He 114 has a much shorter lower wing than usual, but has the same chord as the upper wing, which keeps the wing area ratio similar.
The He 114 was never a great success, was not built in large numbers, and served with the Luftwaffe for only a short time. While the Heinkel He 60 had handled very well on the water but been sluggish in the air, the He 114’s handling while afloat was poor and its performance in the air scarcely better than the aircraft it replaced (Ref.: 24).