No 3: Tested during June 1911, it flew in August; it was a rough copy of the pigeon-tailed Bleriot. The horizontal tail surfaces resembled those of No 2 and were set at a high angle of attack; the rudder, well aft of the tailplane, was similar to those used on the ACRs and the Thomanns, and like them was made of steel tube with bronze bearings. The whole machine may have been built of welded steel tube, either by Thomann or more likely, by Roux. The bent-wood tailskid and undercarriage may have been built by Bleriot, and the wheels were faired with fabric on the outsides. The wings curved downward slightly "'to improve the return to level flight after a bank"; Kaufmann seem to have believed that lift resulted from air pressure underneath the surfaces. A small flat fin was added aft of the rear cockpit. A later version of No 3 with 12-rib wings was described with a 50 hp Anzani; it was the first of the Kaufmann aeroplanes to fly.

   (Span: 10.6 m; length: 7.6 m; 50 hp 6-cylinder Anzani)
  
   No 4: This was the last of his designs, shown under the placard Type de Course at the 1911 Salon, with a triangular rudder and reduced angle of attack on the tailplane. The wings were long, and tapered to pointed tips, curved down like a bird's. A contemporary drawing shows still another wing arrangement, with gracefully upswept tips. The fuselage was narrow, with a wide-set undercarriage. A double-looped skid Bleriot-style held up the tail. This machine may never have been tested at all.

   (Span: 11.6 m; length: 7.6 m; empty weight: 280 kg; payload: 180 kg; 90 hp 6-cylinder Anzani)
  
   In 1913, Kaufmann graduated from the Ecole d'Aeronautique at about 24, and was appointed engineer by Louis Clement. He volunteered in WWI and flew Voisin bombers; in the course of the War he was wounded, and his aeronautical career was ended.