Aleksandr Aleksandrovich Porokhovshchikov built trainers for Tsarist Imperial air service, for Bolsheviks, Red Army and several neighbouring countries. All were derived from 1914 Caudron designs with biplane wings of unequal span and short nacelle with pusher or tractor engine. Single examples of first 3 designs led to substantial production of pusher P.IV tandem-seater, tractor P.IVbis side-by-side and tractor P.IV 2bis tandem. More powerful P.VI and VIbis were built 1921-4.