The production of the Liberty engine so captured popular attention that the public never fairly understood nor appreciated the extent of another production enterprise on the part of those providing motive power for our war airplanes. This was the supplementary manufacture of aero engines other than those which bore the proud appellation of "Liberty."
Let the production figures speak for themselves. In those 19 months, starting with nothing, we turned out complete and ready for service 32,420 aero engines. Of these thousands of engines less than one-half—the exact figure being 15,572—were Liberty engines. The rest were Hispano-Suizas, Le Rhones, Gnomes, Curtisses, Hall-Scotts, and some others, a total of 16,848 in all—built largely for the training of our army of the air.
This production would have been even more notable had the war continued, for at the date of the signing of the armistice the United States had contracted for the construction of 100,993 aircraft engines. Of these 64,100 were to be Liberty engines, so that the total plan of construction of engines other than the Liberty would have produced about 37,000 of them. The total cost of carrying through the combined engine project would have been in the neighborhood of $450,000,000.
While at the outbreak of the war American knowledge of military aviation may have been meager, still it was evident from the start that we would be able to go ahead with certain phases of production on a huge scale without waiting for the precise knowledge of requirements that would come only from an exhaustive study of the subject in Europe. In the first place we knew that we must train our aviators. For this purpose there was at the start no particular need of the highly-developed machinery then in use on the western front. The first aircraft requirement of the early training program was for safe planes, regardless of their type, and motive power to drive them. Later on, when we were better prepared, would come the training that would afford our aviators experience with the fighting equipment. So at the start there was no reason why we should not proceed at once with the construction of such training machines as we knew how to build.
An aviation program for war falls into these two divisions—the equipment required for training and that required for combat. While our organization, particularly through the Bolling commission which we had sent to Europe, was making a study of our combat requirements and while we were pushing forward the design and production of the Liberty engine, we forthwith developed on an ambitious scale the manufacture of training planes and engines in this country.
The training of battle aviators, on the other hand, also separates into two parts, the elementary training and the advanced training. The elementary training merely teaches the cadet the new art of maintaining himself in the air. Later, when he has mastered the rudiments of mechanical flight, he goes into the advanced training, the training in his fighting plane, where he requires equipment more nearly of the type used at the front.
For the elementary training we had some good native material to start with. The Curtiss Airplane Co. had been building training planes and engines both for the English and Canadian air authorities. This was evidently the most available American airplane for our first needs. The Curtiss plane was known as the "JN-4" and it was driven by a 90-horsepower engine called the Curtiss "OX." In the production of this equipment on the scale planned by the Signal Corps, the embarrassing feature, the choke point, was evidently to be the manufacture of the engine. The Curtiss plant at Buffalo for the manufacture of planes could be quickly expanded to meet the Government demands; but the Curtiss engine plant at Hammondsport, N. Y., could not develop the production of "OX" engines up to our needs and at the same time complete the orders which it was filling for the English and Canadian air services.
Consequently, contracts were awarded to the Curtiss Co. for its capacity in the production of "OX" engines, and then the American aviation authorities came to an agreement with the Willys-Morrow plant at Elmira, N. Y., for an additional 5,000 of these motors. Ordinarily it would require from five to six months to equip a plant with the large machine tools and the smaller mechanical appliances necessary for such a contract as this. But the Willys-Morrow plant tooled up in three months and was ready to start on the "OX" manufacturing job.
CURTISS ENGINE, MODEL OX-5.
CURTISS ENGINE, MODEL OX-5.
CURTISS ENGINE, MODEL OX-5.
HALL-SCOTT ENGINES BEING INSTALLED IN AIRPLANE FUSELAGES.
HALL-SCOTT ENGINES BEING INSTALLED IN AIRPLANE FUSELAGES.
HALL-SCOTT ENGINES BEING INSTALLED IN AIRPLANE FUSELAGES.
TWO VIEWS OF LE RHONE 80-HORSEPOWER ENGINE.This is one of the successful rotary engines.
TWO VIEWS OF LE RHONE 80-HORSEPOWER ENGINE.This is one of the successful rotary engines.
TWO VIEWS OF LE RHONE 80-HORSEPOWER ENGINE.
This is one of the successful rotary engines.
If speed in production was required at any point in the aviation development it was here in the manufacture of the elementary training planes and engines. Without training material, no matter how many aviation fields we set in order nor how many student aviators we enlisted, the movement of our flying forces toward the front could not even begin. And here entered an interesting engineering and executive problem that had to be worked out quickly by those in charge of our aircraft construction. If it were plotted on paper, the curve of requirements for aircraft training material would climb swiftly to its peak during the first six or eight months of the war and then decline with almost equal swiftness until it reached a low level. In other words, we must produce the great number of training machines in the shortest time possible in order to put our thousands of student aviators into the air at once over the training fields; but when this training equipment had been brought up to initial requirements, thereafter our needs in this direction could be met by only a small production, since the rate of wastage of such material is relatively low. Once our fields were fully equipped, the same apparatus could be used over and over again as the war went on, with little regard to the improvements of the type of battle planes, so that the ultimate manufacture need be large enough only to keep this equipment in condition.
It soon became evident that the production of Curtiss planes and engines, even under the heavy contracts immediately placed, would not be sufficient to take care of our elementary training needs; and the aviation administration began looking around for other types of aircraft that would fit into our plans. The experts in all branches of war flying which the principal allied nations had sent to the United States, warned us against the temptation to adopt many types of material in order to secure a quick early production. If the training equipment were not closely standardized in types, it would result in confusion and delay, both in training the aviator to fly and in preparing him for actual combat. Such had been the experience in Europe; and we were now given the benefit of this experience, so that we might avoid the mistakes which others had made. We were advised to adopt a single type of equipment for each class of training; but if that were not consistent with the demands for speed in getting our service in the air, then at the most we should not have more than two types either of planes or engines.
In the elementary training program it was evident that we could not equip ourselves with a single type of plane, except at considerable expense in time. Consequently we went ahead to develop another.
We found a training airplane being produced by the Standard Aero Corporation and known as the "Standard-J." The company had been developing this machine for approximately a year, and its plant could be expanded readily to meet a large contract. For the engine to drive this plane we adopted the Hall-Scott "A7A." This was a four-cylinder engine. It had the fault of vibration common to any four-cylinder engine, but it was regarded otherwise by experts as a rugged and dependable piece of machinery. The Hall-Scott Co. was equipped to produce this motor on an extensive scale, since at the time this concern was probably the largest manufacturer ofaviation engines in the United States, with the possible exception of the Curtiss Co. The engine had been used in airplanes built by the Standard Aero Corporation, the Aero Marine Co., and the Dayton-Wright Co. Therefore the Joint Army and Navy Technical Board recommended the Standard-J plane and the Hall-Scott A7A engine as the elementary training equipment to alternate with the Curtiss plane and engine.
The Government placed contracts with the Hall-Scott Co. for 1,250 engines, its capacity. But, since a large additional number would be required, a supplementary contract for 1,000 A7A's was given to the Nordyke & Marmon Co. The Hall-Scott Co. cooperated with this latter concern by furnishing complete drawings, tools, and other production necessities.
When it came to the advanced training for our aviators, more highly developed mechanical equipment was required. There must be two sorts of this equipment. The advanced student must become acquainted with rotary engines such as were used by the French and others to drive the small, speedy chassé planes, while he must also come to be familiar with the operation of fixed cylinder engines, possessing upwards of 100 horsepower. These latter were the engines in commonest use on observation and bombing planes. For each type, the rotary and fixed, we were permitted by our policy to have two sorts of engines in order to get into production as quickly as possible, but not more than two.
Here again we had to survey the field of engine manufacture and select closely, at the same time making in point of speed approximately as good a showing as if we had adopted every engine with claims for our consideration and had told manufacturers of them to produce as many as they could.
In this case of rotary engines, our aviation representatives in Europe advised the production here of Gnome and Le Rhone motors. There were two models of the Gnome engine, one developing 110 horsepower and the other 150. The Le Rhone engine produced 80 horsepower. The Bolling commission had recommended that the Gnome 150 be used in some of our combat planes.
In the spring of 1917 we were producing a few Gnome 110 horsepower engines in this country. The General Vehicle Co. at some time previously had taken a foreign order for these engines. But neither the Gnome 150 nor the Le Rhone 80 had been built in the United States, both of these having been developed and used exclusively in France. The first recommendations from our observers in France advised us to produce 5,000 of the more powerful Gnome 150's and 2,500 Le Rhone 80's.
The production of Gnome engines in this country forms a good illustration of the manner in which aircraft requirements at thefront were constantly shifting, due to the rapid evolution of the science of mechanical flight. Our officers did not hesitate to overrule their previous decisions, if such a course seemed to be justified, even at the cost of rendering useless great quantities of work already done and material already produced. This has been shown in the case of the Liberty engine. At the start we set out to build Liberty 8-cylinder engines on a large scale, only to discontinue this work before it was fairly started; but later on we again took up a Liberty 8-cylinder project on almost as great a scale as had been planned originally.
So with the production of the heavy 150-horsepower Gnome engine. Our European advisors were first of the opinion that we should go heavily into this production. Consequently the equipment end of the Signal Corps projected a program of 5,000 of the large Gnome engines. Such a contract was entirely beyond the capacity of the General Vehicle Co., which had been building the lighter Gnomes. So the Government entered into negotiations with the General Motors Co. to assume the greater burden of this undertaking. Under the pilotage of the aircraft authorities, an agreement was reached for the industrial combination of the General Motors Co. and the General Vehicle Co. The former concern brought its vast resources and numerous factories into the consolidation; while the latter furnished the only skilled knowledge and experience there was in the United States in the art of making rotary engines. This seemed to be a great step in our progress and an achievement in itself; but just as the undertaking of the construction of large Gnome engines was about to be started, events in Europe had caused our observers there to revise their first judgment, and we received cabled instructions recommending that we discontinue the development of the Gnome 150.
The entire program for Gnome 150's was canceled, and thereafter the General Vehicle Co., with its relatively small capacity, was called upon to produce as many of the small Gnome 110's as it could. As a matter of record the production of these engines amounted to 280 in number.
The Signal Corps found it difficult to induce manufacturers in this country to undertake the construction of foreign designed engines at all. The plans and specifications of mechanical appliances furnished by foreign engineers and manufacturers are so different from ours that trouble is invariably experienced in attempts to use them here. Successful concerns in this country naturally hesitated to pick up contracts on which they might fail and thus tarnish their reputations. Our advisors in Europe were insistent that we should produce Le Rhone engines in quantity in the United States, yet it was hard to find any manufacturing concern willing to undertake such a development. Nevertheless, the production of Le Rhone engines proved to be one of the most successful phases of the whole aircraft program. Its story illustrates the obstacles encountered in adapting a foreign device to American manufacture, and it also shows how American production genius can overcome these handicaps.
It was only after strenuous efforts on our part that the Union Switch & Signal Co., of Swissvale, Pa., a member of the Westinghouse chain of factories, was induced to take up the Le Rhone contract. This project called for the production of 2,500 rotary Le Rhones of 80 horsepower each. Let us see how the manufacturers took this totally unfamiliar machine and went about it to reproduce it in this country.
One might think that it would be necessary only to take the French drawings, change the metric system measurements to our own scale of feet and inches, and proceed to turn out the mechanism. But it was not so simple as that. We did receive the drawings, the specifications, the metallurgical instructions and the like, but these we found to be unreliable and unsatisfactory from our point of view. For instance, according to the French instructions the metallurgical requirements for the engine crank-shaft called for mild steel. This was obviously incorrect; and if an error had crept into this part of the plans there was no telling how faulty the rest of them might be. So from the metallurgical standpoint alone this became a laboratory job of analysis and investigation. A sample engine had been sent to us from France. Every piece of metal in this engine was examined by the chemists to determine its proper constituents, and from this original investigation new specifications were made for the steel producers.
The drawings of the engine were quite unsatisfactory from the point of view of American mechanics. They were found to be incorrect, and there were not enough of them. Consequently this required another study on the part of engineers and a new set of drawings to be made up. All of this fundamental work monopolized the time of a large force of draughtsmen and engineers for several months, working under the direction of E. J. Hall and Frank M. Hawley. The engine could not be successfully built without this preliminary study, yet this is a part of manufacture of which the uninitiated have little knowledge.
THREE VIEWS OF BUGATTI 410-HORSEPOWER ENGINE.
THREE VIEWS OF BUGATTI 410-HORSEPOWER ENGINE.
THREE VIEWS OF BUGATTI 410-HORSEPOWER ENGINE.
THREE VIEWS OF THE HISPANO-SUIZA ENGINE.
THREE VIEWS OF THE HISPANO-SUIZA ENGINE.
THREE VIEWS OF THE HISPANO-SUIZA ENGINE.
The production of the Le Rhone engine might have been materially delayed by these difficulties, except for the organizing ability of the executives handling the contract. While the metallurgists were specifying the steel of the engine parts and the engineers were drafting correct plans, the factory officials, with the assistance of the engine production division of the Air Service, were procuring machinery and tooling up the plant for the forthcoming effort. By the time this equipment was installed the plans were ready, the steel mills were producing the proper qualities of metal, and all was ready for the effort. The Gnome-Le Rhone factories in France sent one of their best engineers, M. Georges Guillot, and he assisted in the work at the Union Switch & Signal Co. So rapidly was the whole development carried out that the first American Le Rhones were delivered to the Government in May, 1918, considerably less than a year after the project was assumed by the Union Switch & Signal Co., which concern had not received the plans of the engine until September, 1917. By the time the armistice was signed the company had delivered 1,057 Le Rhone engines. Subsequent contracts had increased the original order to 3,900 Le Rhones, all of which would have been delivered before the summer of 1919, had the coming of peace not terminated the manufacture. Although France is the home of the rotary aviation engine, M. Guillot has certified to the Aircraft Board that these American Le Rhones were the best rotary engines ever built.
When it came to the selection of fixed cylinder engines for our advanced training program, all of the indications pointed to a single one, the Hispano-Suiza engine of 150 horsepower. This was a tried and true engine of the war, tested by a wealth of experience and found dependable. France had used the engine extensively in both its training and combat planes. In 1916 it had been brought to the United States for production for the allies, and when we entered the war the Wright-Martin Aircraft Corporation was producing Hispano-Suizas in small quantity. By the early summer of 1917, however, the motor had fallen behind in the development of combat engines because of the increasing horsepowers demanded by the fighting aces on the front, but it was still a desirable training engine and could, if necessary, be used to a limited extent in planes at the front.
The plane adopted by the American aircraft authorities for this type of advanced training was known as the Curtiss "JN 4H." It was readily adapted for the use of the Hispano-Suiza 150-horsepower engine. Contracts for several thousand of these engines were placed with the Wright-Martin Aircraft Corporation, and up to the signing of the armistice 3,435 engines were delivered. Before we could start the production of this engine it was necessary for the Government to arrange with the Hispano-Suiza Co. for the American rights to build it, this arrangement including the payment of royalties. Incidentally it is interesting to note that royalty was the chief beneficiary of the royalties paid by the American Government, King Alfonso of Spain being the heaviest stockholder of the Hispano-Suiza Co.
Although our policy permitted us to produce a second training engine of the fixed cylinder type, no engine other than the Hispano-Suiza was taken up by us. A number presented their claims forconsideration, but they were one and all rejected. Among these were the Curtiss engines "OXX" and "V." A few of both of these had been used by the Navy, but neither one seemed to the Signal Corps to meet the requirements. The Sturtevant Co. had developed a 135-horsepower engine and built a few of them, while Thomas Bros., at Ithaca, N. Y., had taken the Sturtevant engine and modified it in a way that they claimed improved it, although the changes had not substantially increased the horsepower. This engine was rejected on the ground that it was too low in horsepower to endure as a useful machine through any considerable period of manufacture, and also because it was too heavy per horsepower to accomplish the best results.
To sum it up, our training program was built around the above named engines—the Curtiss "OX" and the Hall-Scott "A7A" for the elementary training machines; the Gnome and Le Rhone, for the rotary engine types of planes in the advanced training; and the Hispano-Suiza 150-horsepower, for the advanced training in fixed-cylinder-engine machines. Between the dates of September 1, 1917, and December 19, 1918, we sent to 27 fields 13,250 cadets and 9,075 students for advanced training. They flew a total of 888,405 hours and suffered 304 fatalities, or an average of 1 fatality for every 2,922.38 flying hours. At one field the training fliers were in the air 19,484 hours before there was 1 fatality; another field increased this record to 20,269 hours; while a third made the extraordinary record of 1 casualty in 30,982 flying hours.
Although we do not possess the actual statistics, the best unofficial figures show that the British averaged 1 fatality for each 1,000 flying hours at their training camps, the French 1 for each 900 flying hours, while the Italian training killed 1 student for each 700 flying hours. These figures are significant, although varying conditions in the types of training programs may account to some extent for the wide differences in numbers of casualties at American as compared with allied training camps.
But while we were producing engines for the training airplanes, both elementary and advanced, we were not staking our whole combat program on the Liberty engine alone, although we expected that engine to be our main reliance in our battle machines. Our organization, both at home and abroad, was on the alert continually for other engines that might be produced in Europe or the United States and which would be so far in advance of anything in use by the air fighters in Europe in 1917 as to justify our production of them on a considerable scale. One of these motors which seemed to promise great results for the future was the Rolls-Royce, which had even then, in 1917, taken its place at the head of the British airplane engines.
Considerable difficulty was experienced in reaching a satisfactory arrangement with the Rolls-Royce Co. We expected to duplicate this engine at the plant of the Pierce-Arrow Motor Car Co., at Buffalo, N. Y., but the British concern objected to this arrangement on the ground that the Pierce-Arrow people were commercial competitors.
It was several months before we could agree on a factory and arrive at a contract satisfactory to both sides. Meanwhile the Liberty engine had scored its great success, and the expected enormous production of Liberties tended to cool the enthusiasm of our aircraft authorities for the Rolls-Royce, as it was evident that the Liberty itself would be as serviceable and as advanced in type as the British product.
The Rolls-Royce Co. wished to manufacture here its "190," an engine developing from 250 to 270 horsepower; and for this effort it was prepared to send to the United States at once a complete set of jigs, gauges, and all other necessary tooling of a Rolls-Royce plant. With this equipment ready at hand the company expected to produce about 500 American-built Rolls-Royce engines before the 1st of July, 1918.
But so rapidly was the evolution of aircraft engines going ahead that even during the time of these negotiations it became evident that something more than 250 horsepower would soon be needed in the fighting planes on the Western front. We therefore abandoned the Rolls-Royce model 190 and started negotiations for the 270-horsepower engine, the latest and most powerful one produced by the Rolls-Royce Co. But for this engine the British concern could not furnish the tooling, which would have to be made new in this country, and this would reduce the schedule of deliveries. As a result no American-built Rolls-Royce engine was ever made.
Another disappointing experience in attempting to produce a foreign designed motor in this country was the project to bring the manufacture of Bugatti engines to the United States. When our European aircraft commission arrived in France, the first experimental Bugatti engine had just made its appearance. It was apparently a long step in advance of any other motor that had been produced. This French mechanism was a geared 16-cylinder engine. It weighed approximately 1,100 pounds and was expected to develop 510 horsepower. It seemed to be the motor to supplement our own Liberty engine construction. Although heavier than a Liberty, it was much more powerful. The first Bugatti engine built in France was purchased by the Bolling commission and hurried to the United States with the urgent recommendation that we put it into production immediately and push its manufacture as energetically as we were pushing that of the Liberty engine.
The Signal Corps acted immediately upon this advice and prepared to proceed with the Bugatti on a scale that promised to make its development as spectacular as that of the Liberty. The Duesenberg Motor Corporation, of Elizabeth, N. J., was even then tooling up for the production of Liberty engines. We took this concern from its Liberty work and directed it to assume leadership in the production of Bugattis. The Liberty engine construction had been centered in the Detroit district. We now prepared to establish a new aviation engine district in the East, associating in it such concerns as the Fiat Plant at Schenectady, N. Y., the Herschell-Spillman Co., of North Tonawanda, N. Y., and several others. For a time the expectation for the Bugatti production ran almost as high as the enthusiasm for the Liberty engine, but the whole undertaking ended virtually in failure, a failure again due to the tremendous difficulty in adapting foreign engineering plans to American factory production.
This was the story of it. In due time the sample Bugatti engine arrived, and with it were several French engineers and expert mechanics. But, once set up, the Bugatti motor would not function, nor was it in condition to run; for, as we discovered, during its test in France a soldier had been struck by its flying propeller. His body had been thrown twice to the roof of the testing shed, and the shocks had bent the engine's crank shaft. Then, too, we learned for the first time that the design and development of this engine had not been carried through to completion and that a great deal of work would be required before the device could be put into manufacture. The tests in France had developed that such a fundamental feature as the oiling system needed complete readjustment, and this was only indicative of the amount of work yet to be done on the engineering side of the production. We did our best with this engine; but to redesign it and develop it so that it could pass the severe 50-hour test demanded by our Joint Army and Navy Technical Board was the work of months, and after that the tooling up of plants had to be accomplished. The American Bugatti was just getting into production when the armistice was signed, a total of only 11 having been delivered.
As we have seen, we were already building several hundred Hispano-Suiza 150-horsepower engines for our training planes. Soon after the arrival of our aircraft commission in France we were advised to go into the additional manufacture of the latest Hispano-Suiza geared engine of 220-horsepower. Consequently the Washington office at once arranged with the Wright-Martin Aircraft Corporation, which was building the smaller Hispano-Suizas, to undertake the production of this newer model also. The preparations for this manufacture had gone on in the Wright-Martin plant for a considerable period of time when further advice from Europe informed usthat the Hispano-Suiza 220 was not performing successfully on account of trouble with the gearing. This fact, of course, canceled the new contract with the Wright-Martin Co., the incident being another of those ups and downs with which the undertaking was replete.
Along in the summer of 1918 the Hispano-Suiza designers in Europe brought out a 300-horsepower engine. By this date the development of military flying had made it apparent that engines of such great horsepower could be used advantageously on the smaller planes. However, the engine plants of the allied countries were already taxed to their capacities by their existing contracts, and the demands of these countries for high-powered engines could not be supplied unless we in America could increase our manufacturing facilities even further.
In following out this ambition, we placed contracts for the production of 10,000 Hispano-Suiza 300-horsepower engines. Of these, 5,000 were to be built by the Wright-Martin Aircraft Corporation. To enable this company to fulfill the new contract we leased to it the plant owned by the Government in Long Island City which had formerly been owned by the General Vehicle Co. The other 5,000 of these engines were to be built by the Pierce-Arrow Motor Car Co. at Buffalo. We also contracted for the entire manufacturing facilities of the H. H. Franklin Co., of Syracuse, N. Y., to aid both the Wright-Martin Corporation and the Pierce-Arrow Co., in this contract. The first of these high-powered Hispano-Suiza engines were expected to be delivered in January, 1919, but this project, of course, was interrupted by the armistice.
To summarize the complete engine program of the aviation development, the total contracts for engines provided for the delivery of 100,993 engines. These were divided as follows:
The delivery of aviation engines of all types to the United States Government, engines produced as part of our war program, were as follows, by months:
The production by types was as follows to November 29, 1918:
At the signing of the armistice the United States had produced about one-third of the engines projected in its complete aviation program.
Of the output of training engines to November 29, 1918, the various airplane plants took 9,069 for installation in planes, 325 (all of these being Le Rhone rotaries) went to the American Expeditionary Forces in France, 515 (all of which were Hispano-Suizas) were taken by the Navy, a single A7A model was sent to one of the allied countries, while 6,376 engines were sent directly to the training fields.
Of the combat engines produced to November 29, 1918 (which classification includes all of the Liberties, the two more powerful types of the Hispano-Suiza, and the Bugatti engine), 5,327 went to the various airplane plants for installation in planes, 5,030 of them were sent directly to the American Expeditionary Forces, 3,746 were turned over to the Navy, 1,090 went to the several allied nations, and 941 were taken by the training fields.
The shipment of aviation engines to Europe, however, does not imply the immediate use of them by our airplane squadrons at the front. In this report shipment to the American Expeditionary Forces means the shipment of engines from the American factories producing them. As a matter of fact several months usually elapsed from the dispatch of an engine from an American shop until it actually reached the Air Service in France, and even then another month might be required to put the engine into actual service. As a result, of the 5,000 and more aviation engines sent to France by the American engine producers, outside of those installed in their planes, less than 3,000 are recorded in the annals of the American Expeditionary Forces as having been received by them up to the end of December, 1918, the missing 2,000 being in that period either somewhere in transit or in warehouses on the route to their destination.
It is of interest to note what makes of foreign engines were used by our airmen in the war operations. An appended table shows the list of those received, their names, their rated powers, the numbers received month by month, and the totals. The records of the American Expeditionary Forces show that the squadrons in all received from all sources 4,715 aviation engines up to the end of the year 1918, but it should be borne in mind that this figure does not include more than 2,000 engines, principally Liberties, recorded on this side of the Atlantic as having been shipped to the Army abroad. Of the 4,715 engines noted as received, 2,710 were Liberties.
None of the foreign engines used by our pilots even approached the Liberty in power. The nearest in power were a Renault and an Hispano-Suiza, both rated at 300 horsepower.