Submarine aircraft carriers are submarines equipped with fixed wing aircraft for observation or attack missions. These submarines saw their most extensive use during World War II, although their operational significance remained rather small. The most famous of them were the ese I400 class submarine and the French submarine although a few similar craft were built by other nations' navies as well.

The submarine aircraft carriers which were actually built, with the exception of the I400 and AM classes, all used their aircraft in supporting roles, usually for reconnaissance. This is in contrast to the typical surface aircraft carrier, whose main function is serving as a base for combat aircraft.

was the first nation to experiment with submarine aircraft carriers, inspired by the Imperial German Naval Air Service commander Oberleutnant zur See Lothar von Arnauld de la Perire. He commanded a unit of two reconnaissance seaplanes (Friedrichshafen FF.29s) in Zeebrugge which had been recently occupied by the Imperial German Army in the early months of World War I. One of the first UBoats to arrive at the Zeebrugge base was Kapitnleutnant Walther Forstmann's U12, which was to play the role of submarine aircraft carrier.

Forstmann ordered the modification of the unarmed FF29 seaplanes so they could carry 26 (12 bombs. This unit made history when on 25 December 1914, one of its newly modified aircraft flew across the English Channel and up the River Thames, dropping its bombs on the outskirts of London where they did little damage. Although chased for a time by three British interceptors, it returned to base safely. On this first ever bombing mission it became apparent that the aircraft suffered more from fuel problems and lack of range than from British defences.

Later encouraged by this success, Arnauld and Forstmann theorized that they could effectively increase the range of their seaplanes by taking the aircraft to the sea on the deck of submarine and placing it in a takeoff position, then launching the planes after the sub partially submerged, allowing the plane to float off. On 15 January 1915, U12 left their Zeebrugge base transporting one bombarmed FF29 on its deck. The submarine left the harbor, seemingly dwarfed by the 53 2 (16.21 wingspan of the fixed wing aircraft, which stretched almost of the 188 (57 length of the small coastal patrol submarine. After U12 had left the safety of the breakwater, however, the captain realized that the heavy swells they were encountering might swamp the aircraft and endanger the operation, he ordered the immediate launch of the seaplane.

Forstmann flooded the sub's forward tanks and despite the pitching of the boat, Arnauld in command, floated the seaplane off the deck's surface without much difficulty and took off. He had originally intended to rendezvous with the sub, but later decided against it. After gaining sufficient altitude, Arnauld's plane left for the British coast. The German officer apparently flew along the English coastline undetected and then made his way back to occupied Zeebrugge. The experiment had been successful, in the sense that the aircraft had been carried out to sea and had safely floated off the submarine's deck. However, it was obvious that some improvements were needed in the procedure and setup.

Arnauld and Forstmann proposed further development experiments to the German Naval Command, but were vetoed as their project was considered technically impracticable. The plans were kept on ice until 1917, when they were reinvestigated in the hope that they would increase the striking power of new German subs such as the longrange cruisetype Unterseeboote, which were to be equipped with aircraft for scouting purposes little seaplanes that could be quickly assembled and dismantled onboard and kept in special compartments on deck but the idea was eventually abandoned as the war came to an end. Stralsund V.19. The first type was designed in 1917 for use aboard the Cruiser submarines that never went into service. The second model was an experimental plane of the flimsiest construction for use in the calmest of seas.

The British also experimented with the aircraftcarrying submarine concept when HM Submarine E22 was fitted out in a manner similar to the German UBoat. It was to be capable of launching its two Sopwith Schneider/Sopwith Baby floatplanes in 1916. However, just as in the German experiment, the aircraft were carried outside and the submarine could not submerge without losing them.

World War I / PostWorld War I examplesMain article: French submarine Surcouf

Surcouf was a French submarine ordered to be built in December 1927, launched 18 October 1929, and commissioned May 1934. At 4,000 (3,600 displacement submerged, Surcouf was the largest submarine in the world at the start of World War II. Her short wartime career is laced with controversy and conspiracy theories.

Surcouf was designed as an "underwater cruiser," intended to seek and engage in surface combat. For the first part of that mission, it carried an observation float plane in a hangar built into the after part of the conning tower; for the second part, it was armed with not only 12 torpedo tubes but also a twin 8 (203 gun turret forward of the conning tower. The guns [url=http://www.bengalsnflofficialauthentic.com/authentic-jeremy-hill-jersey.htm... Jeremy Hill Jersey were fed from a magazine holding 60 rounds and controlled by a director with a 16 6 (5 rangefinder, mounted high enough to view a 7 (11 horizon. In theory, the observation plane could direct fire out to the guns' 15 (24 maximum range. Antiaircraft cannons and machine guns were mounted on the top of the hangar.

The Regia Marina (Italian Navy) developed, in the late1920s, the Ettore Fieramosca, a submarine with a waterproof hangar for a small reconnaissance plane. They gave commissions to the Italian aircraft manufacturers Macchi and Piaggio for two prototypes. Altogether 42 submarines were built with the capability to carry floatplanes. By 1928, the M2 had been fitted with a waterproof hangar and hydraulic catapult and could launch and recover a small seaplane. The submarine and her plane could then act as a reconnaissance unit ahead of the fleet. The American government purchased two CasparHeinkel U1 disassemblable seaplanes for detachment to Anacostia Naval Station for evaluation and testing. Later, one aircraft was lost during an exhibition flight in 1923, but this provided useful technical information.

The Navy accepted the construction of 12 submarinebased aircraft at different private enterprises like CoxKlemin Aircraft (from New York) with their CoxKlemin XS1 design (one prototype and five preproduction aircraft) and another six were ordered from Glenn L. Martin Company (from Baltimore) with their design Glenn Martin MS1, both small disassemblable seaplanes.

Both models were tested in the S1 during October and November 1923. Later, the CoxKlemm company attempted to develop its design with an XS2 model, but the Navy lost interest in the concept. In 1931, another similar concept was born when Loening Aircraft Engineering Corporation presented its design the Loening XSL1[1][2] a small flying boat for submarine trials aboard the S1, but the concept of submarine aircraft carriers was never [url=http://www.bengalsnflofficialauthentic.com/authentic-aj-mccarron-jersey.htm... accepted by the US Navy's submarine service.