The post-armistice production of airplane engines was somewhat greater, both proportionately and in numbers of units delivered. This was due partly to the greater momentum acquired by the engine project, partly to the fact that engines could be stored safely and would retain good military value for years to come, and partly to the necessity of keeping the engine makers at work while their factories were turning to normal production. The total American production of aviation engines on the war contracts was as follows: deliveries to October 31, 1918, 28,509; deliveries thereafter, 13,081; total war production, 41,590. Of these engines 20,493 were Liberty engines, of which about 5,000 were produced after the armistice. About 300 observation balloons were produced after the armistice before the manufacture could be terminated. In one important particular the policy adopted in the demobilization of the war aircraft industry was exactly the opposite of that used in demobilizing the ordnance industry. In working back to a peace footing, it was the policy of the Ordnance Department to reserve complete manufacturing equipments and to set up stand-by plants for the manufacture of some of the most important materials in ordnance supply. On the other hand, in demobilizing the airplane industry it was the policy for the Government not to retain any manufacturing facilities whatsoever. There were strong strategic reasons behind both these policies. For field guns, for recuperators, for shell, and for other important ordnance, there is little or no normal commercial demand; and the only way the Ordnance Department could guarantee the future existence of facilities for producing these materials was to retain the equipment created during the war. But there is, or can be, some commercial demand for airplanes, and some day there will undoubtedly be a great commercial demand for them. It is important to the military welfare of the United States that this country take a foremost place in the improvement of designs and in the production of flying machines for commercial use. Only through the development of a great independent aircraft industry in this country can the Government be assured of the existence of facilities upon which it can rely to give this nation great power in the air. As conditions now are, the Government itself must be the chief customer of the airplane industry, and on the government orders the industry must live until commercial flying begins to develop on a scale comparable at least to the early development of railway transportation in the United States. If the Air Service were to have retained the war manufacturing facilities as government producing and stand-by plants, that act would have dealt a staggering blow to the infant commercial industry in the most uncertain period of its existence.