From mid-1911 Sommer started designating his designs with letters according to a system for which the key seems lost.

   Type K: This was an all-wood biplane with a faired-in nose for the pilot, and a forward elevator mounted on 2 outriggers. The wings were narrower than those of previous machines. It was not successful, being designed for the Army who was not interested in it, since at the time the Army wanted heavier, more powerful aircraft.

   Type R (Type de Place - fortress type): The last of the Sommer biplanes, and the most successful, developed in several variations throughout 1912. By mid-1912 these were called R1, R2, and R3; but by the end of the year only R and R3 were still mentioned. By the time Sommer was building the R-types, he had re-staffed his factory, with the new workers coming from the armament industries and being familiar with precision assembly-work. This big biplane was more modern than it appeared: built of wood, the struts by the engine were steel tube, and the steel-tube landing gear struts were wood-filled. The wooden wing struts were hollow. Controls were mounted in ball-bearings, and piano wire was replaced with cable running through guides of copper tubing. Two rudders were set below the tailplane with its rear elevator, and a forward elevator might be also fitted at will, again to orient the pilot. R2 was a 2-seater, R3 a 3-seater. The crews sat in a cockpit in front of a Renault engine; the fairing on the R2 was open in front, and covered on top on the R3. Different sets of wings were used. One photograph shows 4 ailerons, 2 large and 2 small on the upper wings (R2?); others show 6, with 2 more on the lower wings (R3?). All hung down at rest. 2 of the ailerons were linked to the rudders, supposedly helping in turbulent weather. Type R was fitted with a variety of engines: a 50 or 70 hp Gnome, or a 50 or 70 hp Renault. One Type R was tested in December 1912 with an 80 hp de Dion Bouton V8. The family archives show a Type R with a water-cooled Canton-Unne of probably 110 hp, and a front elevator.

   (R3 - spans: 15.5 m, 12 m; length: 11 m; length including front elevator: 11.7 m; total area: 54 sqm; top speed: 93 kmh; take-off run: 60m; landing run: 30 m; empty weight: c 50 kg; gross weight (fuel and oil for 4 hr): c 900 kg; various engines)

   Type Reliable: This light wooden machine appeared in the press in April 1912; designed for tactical reconnaissance, it was quickly foldable. A pusher, it had no forward elevator, and the pilot sat well forward of the lower wing leading edge. The engine was mounted aft of the propeller. The tailplane had an elevator fitted to it, and the same vertical rudder as on the Types K and L pivoted around a vertical axis at about 1/3 chord, with a tailskid mounted on its leading edge.

   (Spans: 12.5 or 12.8 m, 9 m; length: c 9.5 m; empty weight: 275 kg; 50 hp Gnome)