America’s war associates had developed a multiplicity of types of both planes and engines, with much resulting loss of economy both in production and in the training of the fliers to operate them and of the mechanics necessary for their upkeep. Profiting by this mistake, the Air Service of the United States endeavored to simplify types. The primary need was a standardized, high-powered motor that could be produced in quantity. Two or three engineers devoted themselves to this problem, working out in a few weeks the Liberty Motor, which proved to be a signal contribution to air warfare and to the possibilities of peace time aeronautics. It soon demonstrated its worth for all except the light pursuit plane and won the highest praise from our own airmen and from those of England, France and Italy. By the time it was ready for manufacture battle front needs had begun to indicate the necessity for a still higher horsepower and the making of these complicated changes delayed its completion. The first contract for its manufacture was signed early in September, 1917, and when the “cease firing” order was passed along the battle lines over 15,000 had been turned out and quantity production at a rate of 2,000 per month had been reached, while 16,000 motors of other types brought the total to 31,800. The month of October had seen a total production of 5,600 airplane motors. Advising with the air service officials of England, France and Italy, it was decided that this country could render the most efficient aid by specializing in battle and observation planes, rather than by attempting to produce all of the several kinds into which the developments of air warfare were specializing airplane uses. The types of foreign planes selected for these services had to undergo a certain amount of alteration to fit them for the Liberty motor and for other reasons, but when production began it proceeded rapidly, and over 3,000 were built, together with a large quantity of spare parts for repairs. Other types were being adapted to the American engine, which was considered the best engine for these planes, and new designs were being developed when the armistice was signed, and all of these would very soon have been in quantity production. American designers had been spurred to high pressure effort by the needs of the country and among the planes ready for testing, or already tested, approved and ready for manufacture, were several embodying original ideas that would have made them highly efficient as fighting planes. One of these was so simplified for the purpose of speedy production that it required but one-tenth the number of parts of the ordinary service plane of European design.