As the war progressed, aviation detachments were grouped into larger units:   In spite of Russia's need for airframes and engines, only about 5,600 aeroplanes were built in Russia before October 1917. Much of this was due to the fact that Russian industry could not keep pace with demand. Imperial Russia did not possess the manufacturing capacity to produce engines and airframes in the numbers needed. Thus, the Czarist government relied heavily on imported engines and airframes from France and Britain. Russia's aircraft production slightly outpaced her Austrian opponent, who stayed in the war one year longer, produced about 5,000 aircraft and 4,000 engines between 1914 and 1918. Of course, the output of Russia and Austria-Hungary pale in comparison to the 20,000 aircraft and 38,000 engines produced by Italy and the more than 45,000 aircraft produced in Germany. In addition to construction problems the Imperial Russian Air Service faced great difficulties in keeping the aircraft they did have in the air. Because it was so difficult to get new machines in a timely manner and because the Russians faced a shortage of aircraft for such a large front, the Russian high command kept out of date aircraft flying as long as possible. Thus, Russian pilots flew obsolete machines in combat throughout the war in the face of much better enemy aircraft. The fact that so many obsolescent machines remained in service produced Otryads that were an eclectic mix of aircraft; some front line, others nearly so, and some that should not have been flying. With so many different engines and airframes from French, British and Russian factories, trying to keep the machines flying was a constant challenge for Imperial ground crews. One report from the American War Department dated August 24, 1916 stated that, "The great majority of Russian machines are very dangerous to fly, due to the lack of proper over-hauling and having been tinkered with by inexperienced men. Lack of spare parts induced the Russians to fit magnetos and sparking systems to motors for which they were not built, and this makes the wear and tear excessive all around." The Imperial Russian Air Service, in common with other World War I air services, struggled to find a way of allowing a machine gun to fire safely through the spinning propeller of an aeroplane. The Russian High Command was tardy in realizing the necessity for arming its aircraft throughout 1914 and 1915, leaving frustrated aviators using such impromptu armaments as pistols, rifles, trolled anchors and cables, and other makeshifts. Part of the delay was caused by a paucity of light automatic weapons that an aircraft could lift.