This enormous increase over the original power of the Liberty engine required changes in the construction, notably in increasing the strength of practically all of the working parts, including the crank shaft, the connecting rods, and the bearings. The change also resulted in making scrap iron of a large quantity of the jigs and special tools employed in making the lighter engines. A still further change had to come in the character of some of the steel used in some of the parts, and this went back to the smelting plants, where new and better methods of producing steel and aluminum for the Liberty engine had to be developed.
Thus while there were no fundamental changes in the design of the engine, the increase of its power required a considerable readjustment in the engine plants. Yet so rapidly were these changes made that on the first anniversary of the day when the design of the Liberty engine was begun—May 29, 1918—the Signal Corps had received 1,243 Liberty engines. In this achievement motor history was written in this country as it had never been written before.
From a popular standpoint it may seem that the Liberty engine was radically changed after its inception, but such an assertion is entirely unwarranted; for in the fundamental thing, the design, there was but one change made after the engine was laid down on paper in May, 1917, namely, in the oiling system. The original Liberty engine was partially fed with oil by the so-called scupper system, whereas this later was changed to a forced feed under compression. The scupper feed worked successfully, but the forced feed is foolproof and was therefore installed upon the advice of the preponderance of expert criticism.
It is also true that in working out certain practical manufacturing processes some of the original measurements were altered. But this is a common experience in the manufacture of any internal-combustion engine, and alterations made for factory expediency are not regarded as design changes, nor are they important.
The delivery of 22 motors in December of 1917 was followed by the completion of 40 in January, 1918. In February the delivery was 70. In March this jumped to 122; then a leap in April to 415; while in May deliveries amounted to 620.
The quantity production of Liberties may be said to have started in June, 1918, one year after the engine's conception in Washington. In that month 1,102 motors of the most powerful type were delivered to the service. In July the figure was 1,589; in August, 2,297; in September, 2,362. Then in October came an enormous increase to the total of 3,878 Liberty engines. During the month before the armistice was signed the engine factories were producing 150 engines a day.
In all, up to November 29, 1918, 15,572 Liberty engines were produced in the United States. In the disposal of them the American Navy received 3,742 for its seaplanes; the plants manufacturing airplanes in this country took 5,323 of them; 907 were sent to various aviation fields for training purposes; to the American Expeditionary Forces in France, in addition to the engines which went over installed in their planes, we sent 4,511 Liberty engines; while 1,089 went to the British, French, and Italian air services.
Some of the earliest Liberties were sent to Europe. In January, 1918, we shipped 3 to our own forces in France. In March we sent 10 to the British, 6 to the French, and 5 to the Italians. By June 7 the English tests had convinced the British air minister that the Liberty engine was in the first line of high powered aviation engines and a most valuable contribution to the allied aviation program. The British air minister so cabled to Lord Reading, the British ambassador in Washington. Again on September 26 the British air ministry reported that in identical airplanes the Liberty engine performed at least as well as the Rolls-Royce engine. Birkight, who designed the Hispano-Suiza engine in France, declared that the Liberty engine was superior to any high-powered aviation engine then developed on the Continent of Europe.
