High on the list of contributions made by the Navy to the development of aviation was its insistence, at the very beginning, on the use of scientific methods in designing airplanes. The introduction of aerodynamic principles almost immediately after the first successful flight is one of the most cogent reasons for the rapid advance in aviation. Today it is an accepted fact that any improvement in airplane construction will be secured by such methods, but this was far from true during the first years after the Wright brothers, in 1903, proved that an airplane could be made to support a man and a motor in controlled flight. The early inventors made their first flying machines by trial and error, with a large percentage of error, until Captain Washington Irving Chambers1 and a group of naval officers began the long search for the aerodynamic principles so necessary for building airplanes efficient and safe enough for combat. Theirs was a difficult task because very few treatises on this subject had been written before 1910.
Immediately after the Wrights’ demonstration at Kitty Hawk, the Navy Department was deluged with letters from inventors desirous of selling, among other weird contrivances, a Spider Flyer, which was an early idea for a helicopter; a Birdaplane or Mechanical Duck “adapted by nature to Fly, Float, or Swim,” for $50,000; and a Mechanical Fish to be used both as a submarine and flying machine. Fortunately for the progress of naval aviation, Captain Chambers, then an assistant to the Aid for Material, was detailed in September 1910 to take charge of this correspondence in addition to his other duties. Chambers, with only half a desk and a part time secretary two flights up, soon expanded his assignment as answerer of letters to include the study of the whole problem of airplane construction. With some training and experience in scientific research, Chambers was well fitted for the task ahead of him. Realizing the impossibility of purchasing, at this time, an airplane suitable for use with the fleet, he and a few other officers began to collect all available information on aviation problems.
By answering all the letters sent to the Navy by aviation enthusiasts, Chambers stimulated and directed the efforts of those whom he thought capable of developing airworthy machines by giving them scientific data obtained either from the investigations of his own officers or from European technical and aeronautical institutions. In return he received many valuable suggestions which he sent to naval laboratories for testing. The Captain’s filing cabinet soon became a repository of all new aeronautical ideas, fantastic and otherwise.
When Chambers first started his work, he complained bitterly about the lack of aeronautical books in the naval library and began to collect both American and European writings on subjects even remotely connected with aviation. His favorite ones in this period were written by Langley, Eiffel, and Bryan[1] because they dealt with the scientific theories of design, and Chambers had translations made of most of Eiffel’s writings. During the years he was in charge of naval aviation, Chambers not only collected many copies of scientific articles but also contributed periodic reports of progress in aviation and summaries of scientific discoveries. Although the first successful airplane was flown in America, European inventors were soon producing better ones. Their superiority was due mainly to the fact that they were willing, a little earlier than American manufacturers, to use the mathematical calculations and scientific principles of such men as Eiffel. One of Chambers’ greatest achievements was the early adoption of these theories in America.
When airplanes were first offered to the Navy, some officials in the Department were either indifferent to or frankly skeptical of their value in fleet operations. This was not surprising since the early flying machine was a delicate thing. In spite of this attitude, the Department often sent naval observers to various exhibitions. Lieutenant George C. Sweet and Naval Constructor William McEntee watched the trials of the Wrights’ Army biplanes at Fort Myer in 1908 and 1909; Captain Chambers, Lieutenant N.H. Wright, and McEntee attended the International Aviation Tournament at Belmont Park, New York, and the Aviation Meet at Halethorpe, Maryland, in October and November, 1910; and Lieutenant Theodore Ellyson witnessed some of the events at San Francisco in January, 1911. These exhibitions enabled the naval representatives, who could not attend the European meets, to note the latest advances in civilian aviation which might be of ultimate use to the Navy. Bleriot, Antoinette, and Farman airplanes competed with Wright, Curtiss, and other American machines, enabling the officers to compare the relative merits of both European and domestic aircraft.
Chambers, encouraged by the progress revealed at Belmont Park and Halethorpe, strongly recommended the purchase of several airplanes for the instruction of a few naval officers and “for further investigation of the principles governing their use.” Chambers asked only $25,000 for the first appropriation because he knew that a great deal of investigation had to be done before an airplane would be produced suitable for naval operations. Nevertheless he wanted a few machines, preferably from two different manufacturers, on which his officers could experiment. Not until July, 1911, however, was he granted funds to buy one Wright and two Curtiss airplanes.
Before this date Chambers was fortunately able to initiate the first phase of naval experimentation, a period in which little real scientific work was attempted but one in which the technique of airplane construction was greatly improved. In the autumn of 1911 Glenn Curtiss had established an airfield on North Island, near San Diego, where he could teach flying and build new types of airplanes during the winter months. In December he invited the Secretary of the Navy to send an officer to receive instruction and conduct any experiments of interest to the Navy. Lieutenant Ellyson was chosen by Chambers and worked with Curtiss for a number of years, at the North Island camp during the winter, and at Hammondsport, New York, in the summer. Curtiss, a mechanical genius but untrained in the scientific principles of design, was more than willing to try any new ideas, especially those of value to the Navy. These two, with the constant advice and criticism of Chambers, made many changes in the designs used for the first Curtiss airplanes—changes which were incorporated in the construction of the two airplanes made for the Navy when the 1910 appropriation bill was passed. The most important innovation was the development of the hydroaeroplane, later called a float plane. Curtiss had done some preliminary work on this type but now developed it more fully because it was the kind of aircraft desired by Chambers and Ellyson. Although some new and valuable scientific ideas were contributed by Dr. A. F. Zahm during his occasional visits to Hammondsport, or were gained from European works, most of the problems were solved by the Hammondsport group in the evenings as they sat around the table at Mrs. Mott’s boarding house to discuss the daily accidents. Probably more changes were made as a result of accidents than through the study of aerodynamic theories.
As soon as the Navy acquired its own airplanes a more intensive program of experimentation was started by Captain Chambers and his small group of aviators, Lieutenant Ellyson, Lieutenant John Rodgers, Lieutenant John H. Towers, and Ensign Victor Herbster among others. An aviation camp was set up at Greenbury Point near Annapolis, Maryland, where the work could be carried on with the aid of the personnel and the facilities of the Naval Engineering Experiment Station. The resources of this station had been offered as early as December, 1010, by Captain H. I. Cone, Chief of the Bureau of Steam Engineering, for testing the strength of airplane parts. He had also offered to increase the apparatus for testing engines whenever the Department bought any aircraft. When the first three airplanes reached Annapolis the aviators and employees of the Bureau began to make alterations, replace poorly tooled parts, and repair the machines which were wearing out very quickly. It was not long before both Chambers and Ellyson were complaining that flight instruction was being seriously delayed while the men tinkered. This method of investigation, however, was not adequate for the solution of problems more advanced than the improvement of minor structural details, and Chambers was already looking forward to a time when really accurate scientific work could be carried on in a well equipped laboratory.
While the aviators were busy at Annapolis, Chambers planned further experimental work for another naval laboratory, the Model Basin at the Washington Navy Yard. He realized that better hulls and pontoons for hydroaeroplanes could be designed if preliminary tests were made at the Model Basin, since their seaworthiness requirements were very similar to those for ships. Furthermore, he believed that the design of hydroaeroplanes was the proper business of naval constructors, who had not only the theoretical and experimental training, but also experience acquired as ship designers, to solve the fundamental problems of airplane construction such as stability, buoyancy, propulsion, and speed. In the autumn of 1911 Naval Constructor McEntee, long interested in aviation, not only initiated experiments on hulls and pontoons but also began writing on aerodynamic theories evolved mainly from his knowledge of comparable problems in ship building. He was one of the first to check the metacentric height of an airplane in order to determine in advance the amount of stability a given design would have when the machine was finally built. Using the metacentric height for checking the stability of a ship was an old story to a ship designer, but aircraft manufacturers so far had ignored this aid for solving one of their most difficult problems. Based on his earlier work on ship propellers, McEntee applied the same formulae for determining the best size and shape of air propeller to gain the greatest thrust and speed. His conclusions were then tested on models at the Basin, and during flights with Ellyson and Towers.
The value of using models was a problem long debated both in Europe and America, although extensively used by Eiffel in his laboratory at Auteuil. It was far easier to make a series of changes on models to learn the effect of each alteration on the performance of an airplane than to make them on an aeroplane itself. The cost of these changes was less, and they could be made more quickly, but the problem of translating the results to normal size machines was difficult and not well understood at that time. Chambers nevertheless advised everyone to check his designs in this way before constructing an airplane, although he accepted no fundamental changes in structure until they had been tried out on full size aircraft.
While McEntee and Chambers were making new designs for hulls and pontoons for the Wright and Curtiss machines, the assistance of another Naval Constructor, H. C. Richardson, was secured. Richardson was finally transferred from the Philadelphia Navy Yard to the Model Basin where he could devote full time to the construction of float planes. He also worked at North Island with Curtiss, and together they made newer designs for hydroaeroplanes and tried out the hulls forwarded from the Model Basin by Chambers and McEntee. Richardson was later to design the first airplane built by the Navy, the 82-A, in 1915.
While instigating research in aerodynamic theory and better construction of airplanes, Chambers himself had been working on various methods of using airplanes with ships. During this period the idea of shore-based naval aircraft had not yet been considered and Chambers wanted to find, through use, the particular characteristics most needed by the Navy. Chambers, noting the improvement of aircraft construction at Belmont and Halethorpe, decided that the next step was to investigate the possibility of launching them from the deck of a ship. He persuaded Eugene Ely, a Curtiss flyer, to make such an attempt from the U.S.S. Birmingham on November 14, 1910, at Hampton Roads in a “comparatively old model Curtiss biplane.” A platform, eighty-two feet long by twenty- five feet wide, was rigged on the forecastle deck. Ely took off in a distance of fifty-seven feet and flew to Willoughby Spit. A second demonstration by Ely was staged during the San Francisco exhibition, on January 18, 1911, when he flew from shore to the U.S.S. Pennsylvania. After circling the ship, he landed downwind at forty miles an hour and was brought to a standstill after the hooks, placed under his airplane, had caught eight lines arranged across the deck, attached to sandbags, the first use of an arresting gear. Lieutenant Ellyson had suggested this device only the night before. After an hour on deck, the airplane was turned around and Ely flew back to San Francisco. These flights demonstrated the fact that an airplane could be flown to and from a warship, and Chambers now recommended that some be bought for each of the scout cruisers, these “to be issued in the same manner as boats, anchors, and searchlights, which cost even more.” On February 17, 1911, Curtiss proved that a hydroaeroplane could take off from land, alight on the water alongside a ship, be hoisted on board, then hoisted out again and be flown from the water back to land. Some naval officials thought this was the best method of using an airplane in naval combat, but Chambers saw the difficulty of hoisting machines on and off a ship during actual warfare. Too much time would be lost, especially if an enemy were near, and he urged a return to the previous idea of launching from the deck but without the complications of a platform.
Curtiss and Ellyson then suggested stretching two wire cables from the superstructure of a ship on which the airplane could slide while gaining flying speed. This type of runway could be rigged, the machine launched, and the runway removed in fifteen minutes. This device was successfully tried out at Hammondsport on September 7,1911, but by this time Chambers had conceived the idea of using a compressed air catapult for launching an airplane, and the plan of rigging wire cables on deck was abandoned. Based on his earlier experience in designing a catapult for launching torpedoes, Chambers, with the aid of Naval Constructor Richardson, made one for airplanes. A flat car, shot forward by compressed air, carried the airplane until its flying speed was attained, at which time the car fell away from the airplane. Ellyson, in a Navy hydroaeroplane, was successfully shot from the catapult on November 12, 1912, proving the feasibility of this device. All ships carried air compressors, so power would always be available, and the apparatus was so small it would occupy little space. It could be mounted on top of a turret or quickly transported to any other convenient place. These tests showed, however, that a stronger type would be required when heavier airplanes were made, and Lieutenant Richardson and Lieutenant Commander H. C. Mustin devised better ones.
The first specification for an American military airplane, issued by the Army Signal Corps, had left the details of construction to the designer, merely asking “that it be sufficiently simple in its construction and operation to permit an intelligent man to become proficient in its use within a reasonable length of time”—the time was not specified. To this specification Lieutenant Sweet had added, after seeing the Wright demonstration, certain qualifications he thought necessary for a naval airplane. He wanted one to fly at least forty miles an hour carrying two persons, to be so constructed that it could fly in weather other than dead calm, and could be launched and alight on a ship’s deck or start and land on water, and small enough to be conveniently stowed on board ship. When Chambers finally had the money to buy airplanes, the details of the Curtiss machines were left almost entirely to the discretion of Lieutenant Ellyson. Chambers wanted an hydroaeroplane with amphibian attachments —a hull or floats for the water and retractable landing gear for use if the machine were to be beached or had to alight on land, and Ellyson wanted a slow moving landplane, “one that would hop but not fly,” for training purposes.
After a year spent in trying out the new machines purchased in 1911, and finding a method for launching them, Chambers and the naval aviators prepared a set of general requirements for naval aircraft. These specifications were more definite than the earlier ones; in fact Chambers was afraid some of the requirements might prove to be impossible to fulfill. These specifications, issued in July, 1912, were not only more detailed but also revealed the advance in understanding of the aerodynamic principles which had been worked out by the Navy. For the first time manufacturers were required to provide technical data to show that their machines would be built according to the most modern methods. To provide for an intelligent comparison of designs, each manufacturer was to submit complete stress diagrams showing the distribution of loads on all the main structural parts of the machine, including especially the distribution of loads during a 400- yard turn under full load conditions. Complete statements of the dimensions and material used for each part to show that there was adequate ratio of breaking load to working load had to be included. The location of the center of gravity with full load and with light load, and the locations of the center of pressure for the extreme positions within the safe angles of attack had to be marked on the blue-prints. Since this was a specification for an hydroaeroplane, details of the pontoon were included; it must be more integrated with the whole structure than in earlier designs, should be of light construction but strong, preferably of metal. The hydroaeroplane was to have sufficient stability so that it could ride adrift in a twenty-mile breeze in open water when the engine was stopped, and so that it could be easily controlled in the air. Special consideration was to be given to any manufacturer who could provide automatic or semiautomatic controls which could be disconnected by the pilot when he preferred to use the manual controls.
These and other demands in the specifications of 1912 and 1913 clearly reveal the general characteristics of an airplane required by Chambers and the other naval officers. These men were more interested in safety than in high speed machines of the sporting type. In order to attain safety in the air, Chambers asked principally for more efficient engines, and for airplanes which had the correct amount of stability, and could be easily controlled and maneuvered.
The early inventors thought that the only way to increase the power of an engine was to increase its size and then, in order to provide enough lift to carry the added weight, increase the number of wing panels. But Chambers was quick to realize that an airplane engine could be more efficient without being larger if better methods of construction were used and if the correct size of propeller was determined, so he initiated a number of investigations on these problems. The aviators also were worried about the poor construction of the engines and spent a great deal of their time rebuilding them and reassembling parts which had been put on incorrectly. For instance, some connecting rods had been put on backwards on an engine delivered to Annapolis in December, 1912, “but made no difference as to the running of the motor”; nevertheless the aviators changed the rods. In other cases they found that parts had been badly designed, and they suggested changes or made them themselves. By 1912 some foreign manufacturers were making more efficient engines than their American competitors, but Chambers was opposed to the purchase of these because of the difficulty of getting spare parts. Nevertheless the Navy bought a few to study their design.
Chambers’ major objective throughout his whole career was to discover ways of making an airplane more inherently stable. The early inventors paid scant attention to this problem, trusting to the skill of the pilots to keep the machines from crashing. But this unscientific attitude was scorned by the Navy. Chambers undoubtedly read and wrote more on this than on any other problem of construction, and did more than any one else in America to awaken manufacturers to the necessity of building stability into an airplane. He warned, however, that the amount of stability would have to be varied according to the type of airplane. A pursuit plane should have less than a scout because too much inherent stability makes an airplane hard to maneuver, and too little forces the pilot to exert all his attention and energy to keep the machine under control.
Stability can be achieved in a number of ways, but one of the first to be tried was to improve the stability of the wings, since the early airplanes had practically no tail areas to improve balance. Following the teaching of Langley, Chambers himself believed that tandem wings would give the right amount of stability; but, fortunately for the development of military aircraft, few of this type were made, and none were purchased by the Navy. He likewise favored the Dunne tailless biplane with swept-back wings which was stable but difficult to maneuver. Later the Navy bought two Dunne-type machines built by the Burgess Company and Curtis, but soon abandoned the type as too hard to control in combat.
Another important factor in the problem of stability was the correct location of the center of gravity and the latter’s relation to the line of thrust and the center of pressure at different angles of attack. Understanding little about the importance of this relationship, the first inventors did not bother to determine the center of gravity until the machine was finished. The last thing Ellyson did before accepting the Triad, the Navy’s first hydroaeroplane, was to fly it around in order to find its center of gravity in the air and on the water.
Controllability, although closely allied to that of stability, was another problem which caused a great deal of trouble. Control surfaces, such as ailerons, elevators, and rudders are used on airplanes to increase balance and to control the rotations of the machine about its three axes. The location, shape, and size of these early surfaces differed considerably and were, on the whole, inefficient. Since there was no well-defined tail area, the ailerons were placed between the wings, and the elevators were often put in front of the wings. Even the rudders were sometimes to be found attached to the wings, although usually placed at the end of an outrigger extending to the rear of the machine. But finally, as a result of Chambers’ constant demand for greater controllability, and the experiments of Richardson and McEntee at the Model Basin, balanced control surfaces were developed. By this time the aerodynamic advantage of a tail area had been discovered by the English scientist, Bryan, and the controls could be placed at the end of the tail area. Chambers not only demanded more efficient control surfaces but also some means of obtaining automatic stability during flight. He opposed the idea of a single gyroscope, having learned through his experiments with torpedoes that a single one was worse than none at all, so refused all those which were offered to him. But he finally secured a double gyroscope made by the Sperry Company and this greatly improved the action of the naval airplanes.
Considering the inadequate facilities for aeronautical research available in America during Chambers’ time, a surprising number of improvements were made in airplane design. But Chambers was not yet satisfied. He knew that America had about reached the limit of its scientific knowledge and no further progress would be possible until an aeronautical laboratory was built. The facilities of the Model Basin and the Experimental Station, although fully utilized, were not adequate for all necessary investigations. The naval officers who had been doing most of the work on aircraft were good but, with a few exceptions, they lacked sufficient scientific training. Furthermore, experimental work was interfering with their duties as instructors and flyers. He wanted a well- equipped laboratory, staffed with scientifically trained specialists, so that all the uncertain factors regarding the physical properties and aerodynamic laws could be investigated. These specialists could then furnish the constants, laws, formulae, and other information needed by the aeronautical engineers to enable them to construct airplanes efficient enough for naval warfare. Congress, however, did not pass his bill to establish a national laboratory but, largely due to the efforts of Chambers, the Regents of the Smithsonian Institution on May 1, 1913, established the Langley Aerodynamical Laboratory. From this laboratory developed the National Advisory Committee for Aeronautics which at last fulfilled Chambers’ idea of a true research institution. With the establishment of laboratories the pioneer period of aviation was brought to an end.
During the period from 1908 to 1913, the Navy did far more than buy a few airplanes and hold demonstrations in the use of airplanes with the fleet. Naval officers, by constantly insisting on the scientific treatment of the problems of airplane design, by drawing trained engineers into the field of naval aviation, and by demanding the establishment of aeronautical laboratories in America, did much to change the “art,” as it was then called, into the “science” of aviation.
With A.B., A.M. and Ph.D. degrees from Vassar College, The University of California, and the University of Chicago, Dr. Welborn has also studied at Oxford University, the University of Paris, and Radcliffe College. She taught history at Hood College, Northeastern University, and Florida State College. Subsequently she was for eight years a research assistant and staff member at the Carnegie Institution of Washington, working in the history of science. At present she is one of the historians in the Naval Aviation History Unit, Navy Department, Washington, D. C.