In a flying boat, the main source of buoyancy is the fuselage, which acts like a ship's hull in the water. Most flying boats have small floats mounted on their wings to keep them stable. All large seaplanes have been flying boats, their great weight supported on their hull.
The first Brandenburg flying-boat was the 3-seat flying boat developed by Ernst Heinkel from a Lohner design and built in small numbers for the German and Austro-Hungarian Navies in 1915. In 1916 Heinkel produced an original design for a single-seat wooden-hulled fighter flying-boat, which he named CC after Camillo Castiglioni, financial controller of the Brandenburg company. The CC was characterized by 'starstrut' interplane bracing like that used for the D.II.
After flight trials with the prototype a single CC was ordered by the German Navy. This was delivered to Warnemunde in February 1917, powered by a 150hp Bz.III engine and armed with a centrally mounted Spandau front gun.
Two CC production batches totaling thirty-five aircraft were delivered during 1917; these had wing radiators and a twin-Spandau armament. Some also had slightly lengthened hulls. Major user of the CC was the Austro-Hungarian Navy, for whom the type was built by Phoenix.Hansa Brandenburg
Designated in the A class in Austrian service, the flying-boats were used up and down the Adnatic in defense of ports and naval bases. Like their German counterparts, they were at first fitted with one. and later with two, machine-guns; it may be supposed that these were the domestic 8mm Schwarzlose weapon.
The W.18 single-seat fighter flying boat was, like the CC that it supplanted, intended primarily for the Austro- Hungarian Navy. The prototype was flown early in 1917 with a 150hp Benz Bz III six-cylinder water-cooled engine, and production with a 200hp Hiero engine was undertaken on behalf of the Austro-Hungarian Navy, a total of 47 being delivered between September 1917 and May 1918.
Brandenburg W.18: this improved version of the Brandenburg CC had some aerodynamic refinements, of which the most important abandoning the "star" wing struts in favor of more conventional layout. Armament normally comprised two fixed forward-firing 8mm Schwarzlose machine guns
The W.18 was employed for both station defence and fighter patrol tasks. One Benz-engined example was delivered to the German Navy in December 1917.
The Hansa-Brandenburg W.20 was a German submarine-launched reconnaissance flying boat of the World War I era, Ernst Heinkel designed and Hansa-Brandenburg began construction sometime late 1917, early 1918.Only three W.20s were built.
Due to the need to be stored in a water tight container which could be mounted on the deck of a submarine the W.20 was a small single-seat biplane flying boat that was designed to be assembled and dismantled quickly. It had a slender hull on which was mounted a biplane wing and a conventional braced tailplane.
The Hansa-Brandenburg W.20 was powered by an Oberursel rotary engine mounted on struts between the wings driving a pusher propeller. The pilot had an open cockpit just forward of the lower wing. Because of the slender hull stabilising floats were fitted below and at the end of the lower wings.
The W 20 was a quick and dirty solution, with little thought given to the actual problem of meeting the operational requirements. The engine and fuel tank, mounted independent of the wing cellule, could be folded backwards upon the rear fuselage for storage. It was specified by the German Marine that an untrained crew could assemble and disassemble the machine without using tools, except a hammer.
Submarine "cruisers" from the large German type U139 and U155 are cited as suitable for the placement of the water tight container. No German submarine was ever fitted with a water tight capsule before the Armistice.