The A.E.G. R.I was a 'Giant' class bomber produced during 1918, but that never entered production, and suffered the loss of the first prototype.
The 'R' giant class bombers were the largest German aircraft of the First World War, and were designed for long range bombing missions with high payloads and long ranges. The most famous giants were built by the Zeppelin-Werke Staaken, but a number of other companies also produced 'R' class designs.
The two A.E.G. giants, R.I 21/16 and R.I 22/16 were ordered in 1916, in an attempt to take advantage of A.E.G.'s experience with twin engined bombers. A.E.G. produced a four engined aircraft with all four engines carried inside the fuselage. Power was transmitted to the two propellers via gear boxes and transmission shafts. This system caused a great deal of vibration, and so the four engines were placed on a massive engine mount which formed the heart of the aircraft. One engine had a Bosch inertia starter, and the other three were then started from the running engine. Early on each engine had its own radiator, but these were later merged into two larger radiators.
The fuselage was built with an all-steel structure. The wings had a mix of steel and duraluminum. The fuselage was covered with plywood from the nose to the rear of the engine room, and then with fabric.
The tail was unusual. It had a large horizontal tail plane, which could be moved a short distance up or down, and separate elevators, mounted five feet above the tailplane. Two rudders were carried between the tail plane and elevators.
The observer's cabin was in the nose, and had glass windows. It was accessed via a ladder from below, or from the engine room. Above it was a two man machine gun position. This cabin was originally semi-enclosed, but this was later turned into a standard open cockpit.
Behind the observer's cabin was the engine room, which was above the main landing gear.
The pilot's cabin was positioned behind the engines and wings, in order to improve his view during landings. To reach his cabin the pilots had to enter the observer's cabin and then pass through the engine room. There was room for two pilots, each with their own controls.
The wireless cabin was behind the pilot's cockpit. It had large windows on each side, and a ventral machine gun position in the floor.
R.I 21/16 was completed during 1918 and her initial tests went well. Engine ground tests were carried out on 23 and 30 May 1918. The aircraft made its maiden flight on 14 June, and flew for 27 minutes carrying a 1,190kg payload. Landing was difficult, and the aircraft had to be modified to move weight forward.
It was then decided to replace the propellers. The glue in the new propellers required ten days to be safe, but the increasingly dire situation at the front meant that the test programme was accelerated. After only four days the propellers were installed. On 3 September one propeller broke apart after an hour in the air. A transmission shaft broke loose and smashed the centre section of the aircraft, which crashed, killing seven men (including the person who had insisted on the test).
Work on R.I 22/16 was suspended after the crash and the aircraft was never completed. It was scrapped after the end of the First World War.
A.E.G. also worked on a number of other R-type aircraft, none of which got beyond the design stage. These included the monoplane R.II, which was to be powered by eight engines and a massive triplane that was developed by A.E.G. and Aviatik.
Engine: Four Mercedes D.IVa
Power: 260hp each
Crew: At least 7
Span: 118ft 1 1/2in
Length: 63ft 11 1/2in
Height: 20ft 10in
Empty weight: 19,8345lb
Loaded weight: 28,003lb
Max speed: not known
Climb Rate: not known
Armament: Up to five machine guns