Considerable progress was made in the adaptation of other types of foreign planes to the American-made engines, and in the development of new designs. The U. S. D. 9A, embodying some improvements over the De Haviland 4, was expected to come into quantity production in the near future. The Bristol Fighter, a British plane, was redesigned to take the Liberty 8 and the Hispano-Suiza 300 h. p. engines. A force of Italian engineers and skilled workmen was brought to America to redesign the Caproni night bomber to take three Liberty motors, and successful trial flights of this machine have been made. Several new models are under experimentation. Chief of these is the Le Père two-seater fighter, designed around the Liberty motor, the performance of which is highly satisfactory. Several of these planes were sent overseas to be tested at the front. PRODUCTION OF SERVICE ENGINES In view of the rapid progress in military aeronautics, the necessity for the development of a high-powered motor adaptable to American methods of quantity production was early recognized. The result of the efforts to meet this need was the Liberty motor—America’s chief contribution to aviation, and one of the great achievements of the war. After this motor emerged from the experimental stage, production increased with great rapidity, the October output reaching 4,200, or nearly one-third of the total production up to the signing of the armistice. The factories engaged in the manufacture of this motor, and their total production to November 8, are listed in Table 21. Table 21.—Production of Liberty motor to November 8, 1918, by factories: Packard Motor Car Co. 4,654 Lincoln Motor Corporation 3,720 Ford Motor Corporation 3,025 General Motors Corporation 1,554 Nordyke & Marmon Co. 433 ————— Total 13,386 Of this total, 9,834 were high-compression, or army type, and 3,572 low-compression, or navy type, the latter being used in seaplanes and large night bombers. In addition to those installed in planes, about 3,500 Liberty engines were shipped overseas, to be used as spares and for delivery to the Allies. Other types of service engines, including the Hispano-Suiza 300 h. p., the Bugatti, and the Liberty 8-cylinder, were under development when hostilities ceased. The Hispano-Suiza 180 h. p. had already reached quantity production. Nearly 500 engines of this type were produced, about half of which were shipped to France and England for use in foreign-built pursuit planes. Table 22 gives a résumé of the production of service engines by quarterly periods: Table 22.—Production of service engines in 1918.