To meet the extensive demands for a high-grade lubricating oil, castor beans were imported from India and a large acreage planted in this country. Meanwhile research work with mineral oils was carried on intensively, with the result that a lubricant was developed which proved satisfactory in practically every type of aeroplane motor, except the rotary motor, in which castor oil is still preferred.
PRODUCTION OF TRAINING PLANES AND ENGINES
When war was declared the United States possessed less than 300 training planes, all of inferior types. Deliveries of improved models were begun as early as June, 1917. Up to November 11, 1918, over 5,300 had been produced, including 1,600 of a type which was temporarily abandoned on account of unsatisfactory engines.
Planes for advanced training purposes were produced in quantity early in 1918; up to the signing of the armistice about 2,500 were delivered. Approximately the same number was purchased overseas for training the units with the Expeditionary Force.
Several new models, to be used for training pursuit pilots, are under development.
Within three months after the declaration of war extensive orders were placed for two types of elementary training engines. Quantity production was reached within a short time. In all about 10,500 have been delivered, sufficient to constitute a satisfactory reserve for some time to come.
Of the advanced training engines, the three important models were of foreign design, and the success achieved in securing quantity production is a gratifying commentary on the manufacturing ability of this country. The total production up to November 11 was approximately 5,200.
PRODUCTION OF SERVICE PLANES
The experience acquired during the operations on the Mexican border demonstrated the unsuitability of the planes then used by the American Army. Shortly after the declaration of war, a commission was sent abroad to select types of foreign service planes to be put into production in this country. We were confronted with the necessity of redesigning these models to take the Liberty motor, as foreign engine production was insufficient to meet the great demands of the Allies. The first successful type of plane to come into quantity production was a modification of the British De Haviland 4—an observation and day bombing plane. The first deliveries were made in February, 1918. In May, production began to increase rapidly, and by October a monthly output of 1,200 had been reached. Approximately 1,900 were shipped to the Expeditionary Force prior to the termination of hostilities.
The Handley Page night bomber, used extensively by the British, was redesigned to take two Liberty motors. Parts for approximately 100 planes have been shipped to England for assembly.