Figure 16.—Shop engine, 1901, showing governor and exhaust valve cam. (Photo courtesy R. V. Kerley.)
Figure 16.—Shop engine, 1901, showing governor and exhaust valve cam. (Photo courtesy R. V. Kerley.)
The engine was of normal stationary powerplant design, having a heavy base and two heavy flywheels, one on each side of the crank. These werenecessary to ensure reasonably uniform rotational speed, as, in addition to having only one cylinder, the governing was of the hit-and-miss type. It had a 6×7-in. bore and stroke and would develop slightly over 3 hp at what was apparently its normal operating speed of 447 rpm, which gives an MEP of 27 psi.
The engine is noteworthy not only for its very successful operation but also because it incorporated two quite ingenious features. One was the speed-governing mechanism. As in the usual hit-and-miss operation, the engine speed was maintained at a constant value, the output then being determined by the number of power strokes necessary to accomplish this. The governor proper was a cylindrical weight free to slide along its axis on a shaft fastened longitudinally to a spoke of one of the flywheels. A spring forced it toward the center of the wheel, while centrifugal force pulled it toward the rim against the spring pressure. After each opening of the valve the exhaust-valve actuating lever was automatically locked in the valve-open position by a spring-loaded pawl, or catch. The lever had attached to it a small side extension, or bar, which, when properly forced, would release the catch and free the actuating lever. This bar was so positioned as to be contacted by the governor weight when the engine speed was of the desired value or lower, thus maintaining regular valve operation; but an excessive speed would move the governor weight toward the rim and the exhaust valve would then be held in the open position during the inlet stroke, so no cylinder charge would be ingested. Since the ignition was not mechanically timed, the firing of the charge was dependent only on the compression of the inlet charge in the cylinder, so it made no difference whether the governor caused the engine to cease firing for an odd or even number of revolutions, even though the engine was operating on a 4-stroke cycle at all times.
Figure 17.—Shop engine, 1901, showing operation of exhaust valve cam. (Pratt & Whitney drawing.)
Figure 17.—Shop engine, 1901, showing operation of exhaust valve cam. (Pratt & Whitney drawing.)
The exhaust valve operating cam was even more ingenious. To obtain operation on a 4-stroke cycle and still avoid the addition of a half-speed camshaft, a cam traveling at crankshaft speed was made to operate the exhaust valve every other revolution (see Figure17). It consisted of a very slim quarter-moon outline fastened to a disc on the crankshaft by a single bearing bolt through its middle which served as the pivot about which it moved. Just enough clearance was provided between the inside of the quarter-moon and the crankshaft to allow the passage of the cam-follower roller. The quarter-moon, statically balanced and free to move about its pivot, basically had two positions. In one the leading edge was touching the shaft (Figure17b), so that when the cam came to the cam follower, the follower was forced to go over the top of the cam, thus opening the exhaust valve. When the cam pivot point had passed the roller, the pressure of the exhaust valve spring forced the following edge of the caminto contact with the shaft and this movement, which separated the leading edge of the cam from the shaft, provided sufficient space between it and the shaft for the roller to enter (Figure17c). Thus, when the leading edge of the cam next reached the roller, the roller, being held against the crankshaft by the valve spring pressure (Figure17d), entered the space between the cam and the shaft and there was no actuation of the valve. In exiting from the space, it raised the trailing edge of the cam, forcing the leading edge against the shaft (Figure17a) so that at the next meeting a normal valve opening would take place. The cam was maintained by frictionalone in the position in which it was set by the roller, but since the amount of this could be adjusted to any value, it could be easily maintained sufficient to offset the small centrifugal force tending to put the cam in a neutral position.[20]
Angle, Glenn D.,51Baby Grand Racer,47Baker, Max P.1,10,26,28Bariquand et Marré,43,44-45,57-58Beaumount, William Worby,9,25Bristol Siddeley Engines, Ltd.,44-45Carillon Park Museum, Dayton, Ohio,ix,5n,7,37Chanute, Octave,28Chenoweth, Opie,ix,22,35,42,63Christman, Louis P.,ix,7,8,28Cole, Gilmoure N.,ixClarke, J. H.,18Daimler-Benz A. G.,ix,10,13Engineers Club, Dayton, Ohio,ix,32Ford, Henry,8Ford, Henry, Museum, Dearborn, Michigan,8,64Forest, Fernand,11Franklin Institute, Philadelphia, Pennsylvania,ix,47Gough, Dr. H. J.,58nHowell Cheney Technical School, Manchester, Connecticut,x,14,15Kelly, Fred C,4nKerley, R. V.,ix,65Kitty Hawk Flyer,ii,3Langley [Samuel P.] Aerodrome,9,62Loening, Grover C,13nManly, Charles L.,9,62Maxim, Sir Hiram Stevens,3McFarland, Marvin W.,1,33,47,61Miller-Knoblock Manufacturing Co., South Bend, Indiana,26National Park Service, Cape Hatteras National Seashore,ii,ixNeue Automobil-Gesellschaft,43Porter, L. Morgan,ixPratt & Whitney Aircraft Corp.,v,x,37,40-41,49,52,53,67Pruckner, Anton,33Rockwell, A. L.,ix,37Santos-Dumont, Alberto,11Science Museum, London,x,5,6,7,8,11,21,23,26Taylor, Charles E.,5,64United Aircraft Corp.,v,xWestern Society of Engineers,2Whitehead, Gustave,33Wittemann, Charles,33nWright, Bishop Milton (father),28Wright, Katherine (sister),4Zenith carburetor,52
Angle, Glenn D.,51
Baby Grand Racer,47Baker, Max P.1,10,26,28Bariquand et Marré,43,44-45,57-58Beaumount, William Worby,9,25Bristol Siddeley Engines, Ltd.,44-45
Carillon Park Museum, Dayton, Ohio,ix,5n,7,37Chanute, Octave,28Chenoweth, Opie,ix,22,35,42,63Christman, Louis P.,ix,7,8,28Cole, Gilmoure N.,ixClarke, J. H.,18
Daimler-Benz A. G.,ix,10,13
Engineers Club, Dayton, Ohio,ix,32
Ford, Henry,8Ford, Henry, Museum, Dearborn, Michigan,8,64Forest, Fernand,11Franklin Institute, Philadelphia, Pennsylvania,ix,47
Gough, Dr. H. J.,58n
Howell Cheney Technical School, Manchester, Connecticut,x,14,15
Kelly, Fred C,4nKerley, R. V.,ix,65Kitty Hawk Flyer,ii,3
Langley [Samuel P.] Aerodrome,9,62Loening, Grover C,13n
Manly, Charles L.,9,62Maxim, Sir Hiram Stevens,3McFarland, Marvin W.,1,33,47,61Miller-Knoblock Manufacturing Co., South Bend, Indiana,26
National Park Service, Cape Hatteras National Seashore,ii,ixNeue Automobil-Gesellschaft,43
Porter, L. Morgan,ixPratt & Whitney Aircraft Corp.,v,x,37,40-41,49,52,53,67Pruckner, Anton,33
Rockwell, A. L.,ix,37
Santos-Dumont, Alberto,11Science Museum, London,x,5,6,7,8,11,21,23,26
Taylor, Charles E.,5,64
United Aircraft Corp.,v,x
Western Society of Engineers,2Whitehead, Gustave,33Wittemann, Charles,33nWright, Bishop Milton (father),28Wright, Katherine (sister),4
Zenith carburetor,52
*U.S. GOVERNMENT PRINTING OFFICE: 1971—397-764
Manuscriptfor serial publications are accepted by the Smithsonian Institution Press, subject to substantive review, only through departments of the various Smithsonian museums. Non-Smithsonian authors should address inquiries to the appropriate department. If submission is invited, the following format requirements of the Press will govern the preparation of copy.
Copymust be typewritten, double-spaced, on one side of standard white bond paper, with 1-1/2" top and left margins, submitted in ribbon copy with a carbon or duplicate, and accompanied by the original artwork. Duplicate copies of all material, including illustrations, should be retained by the author. There may be several paragraphs to a page, but each page should begin with a new paragraph. Number all pages consecutively, including title page, abstract, text, literature cited, legends, and tables. A manuscript should consist of at least thirty pages, including typescript and illustrations.
Thetitleshould be complete and clear for easy indexing by abstracting services. Include anabstractas an introductory part of the text, followed by an identification of theauthorthat includes his professional mailing address. Atable of contentsis optional. Anindex, if required, may be supplied by the author when he returns page proof.
Headingsare to be used discriminately and must be typed with extra space above and below.
For matters of general style (including bibliography and footnotes or notes) followA Manual of Style, 12th edition, University of Chicago Press, 1969. For more detailed treatment on footnotes and bibliography see Citation Style Manual prepared for MHT publications (October 1963). Use the modern order of citing dates: 29 February 1972.
Simpletabulationsin the text (e.g., columns of data) may carry headings or not, but they should not contain rules. Formal tables must be submitted as pages separate from the text, and each table, no matter how large, should be pasted up as a single sheet of copy.
Use themetric systeminstead of (or in addition to) the English system.
Illustrations(line drawings, maps, photographs, shaded drawings) can be intermixed throughout the printed text. They must be clearly numbered in sequence, as they are to appear in the text. They will be termedFiguresand should be numbered consecutively; if a group of figures is treated as a single figure, however, the individual components should be indicated by lowercase italic letters on the illustration, in the legend, and in text references: "Figure 9b." Type (double spaced) all legends on a page or pages separate from the text and not attached to the artwork.
In thebibliographyspell out book, journal, and article titles, using initial caps with all words except minor terms such as "and, of, the." (For capitalization of foreign language titles, follow the national practice of the language.) Underscore (for italics) book and journal titles. Use the parentheses-colon system: 10(2):5-9 for volume, number, and page citations.
Notesandfootnotes, accompanying a manuscript, are to be typed consecutively, double-spaced, and on sheets separate from the text. In typing the notes the number should be typed on the line and followed by a period. The footnote number should be typed slightly above the line and should follow any punctuation mark except a dash.
Forfree copiesof his own paper, a Smithsonian author should indicate his requirements on "Form 36" (submitted to the Press with the manuscript). A non-Smithsonian author will receive fifty free copies; order forms for quantities above this amount with instructions for payment will be supplied when page proof is forwarded.
1: An extensive bibliography, essentially as complete at this time as when it was compiled in the early 1950s, is given on pages 1240-1242 of volume 2 ofThe Papers of Wilbur and Orville Wright, 1953.2: Max P. Baker was a technical adviser to the Wright estate and as such had complete access to all of the material it contained.3: In the 1890s the wealthy inventor Sir Hiram Stevens Maxim conducted an experiment of considerable magnitude with a flying machine that utilized a twin-cylinder compound steam powerplant. It was developed to the flight-test stage.4: Fred C. Kelly,Miracle at Kitty Hawk, 1951.5: Charles E. Taylor (Charley Taylor to the many who knew him) was in effect the superintendent of and also the only employee to work in the original small machine shop. A most versatile and efficient mechanic and machine operator, he made many parts for all of the early engines, and in the manner of the experimental machinist, worked mainly from sketches. He also had charge of the bicycle shop and its business in the absence of the Wrights.6: This is a charitable agency set up by the late Colonel and Mrs. E. A. Deeds primarily for the purpose of building and supporting the Deeds Carillon and the Carillon Park Museum in Dayton, Ohio.7: The Science Museum expressed a desire to have these but never received them. There is a reference to them in a letter to the Museum from the executors of his estate dated 20 February 1948, but is seems rather obvious from the text that by this time the drawings mentioned by Orville Wright in his 1943 letter had become confused with those being prepared by Christman for the Smithsonian Institution. The Science Museum did have constructed from its own drawings a very fine replica which is completely operable at this time.8: There is a third set of drawings prepared by the Ford Motor Company also marked as being of the 1903 engine and these are rather well distributed in various museums and institutions. What this set is based on has been impossible to determine but it is indicated from the existence of actual engines and parts and the probable date of their preparation (no date is given on the drawings themselves) that they were copied from drawings previously made, and therefore add nothing to them. The Orville Wright-Henry Ford friendship originated rather late, considering Ford's avid interest in history and mechanical things. This tardiness could possibly have been the result of Wright coolness—a coolness caused by a report, at the time the validity of the Wright patents was being so strongly contested, that Ford had advised some of those opposing the Wrights to persevere and to obtain the services of his patent counsel who had been successful in overturning the Selden automobile patent. If this barrier ever existed it was surmounted, and Ford spent much effort and went to considerable expense to collect the Wright home and machine shop for his Dearborn museum. The shop equipment apparently had been widely scattered and its retrieval was a major task. It is most likely that the drawings resulted from someone's effort to follow out an order to produce a set of Ford drawings of the original engine. A small scale model of the 1903 flight engine, constructed under the supervision of Charles Taylor, is contained in the Dearborn Museum.9: Charles L. Manly was engaged in the development of the engine for the Langley Aerodrome. See also footnote to Table on page62.10: Fernand Forest,Les Bateaux Automobiles, 1906.11: Grover Loening, letter of 10 April 1963, to the Smithsonian Institution.12: Assuming a rich mixture, consumption of all the air, and an airbrake thermal efficiency of 24.50% for the original engine, the approximate volumetric efficiency of the cylinder is calculated to have been just under 40%.13: A rather thorough stress analysis of the rod shows it to compare very favorably with modern practice. In the absence of an indicator card for the 1903 engine, if a maximum gas pressure of five times the MEP is assumed, the yield-tension factor of safety is measurably higher than that of two designs of piston engines still in wide service, and the column factor of safety only slightly less. The shear stresses in the brazed and threaded joints are so low as to be negligible.14: Rankin Kennedy,Flying Machines—Practice and Design, 1909.15: Considerable doubt surrounds Whitehead's actual flight accomplishments, but Pruckner's engines were certainly used, as several were sold to early pioneers, including Charles Wittemann. It is probable that the specific power output was not very great, for the air-cooled art of this time was not very advanced and Pruckner had a rather poor fin design. But the change to water cooling eliminated this trouble, and the engines were most simple, should have been relatively quite light, and with enough development could probably have been made into sufficiently satisfactory flying units for that period.16: A drawing of the camshaft is held by The Franklin Institute.17: Baker states that the first crankshaft was made from a slab of armor plate and if this is correct the alloy was a rather complex one of approximately .30-.35 carbon, .30-.80 manganese, .10 silicon, .04 phosphorus, .02 sulphur, 3.25-3.50 nickel, 0.00-1.90 chromium; however, all the rest of the evidence, including Orville Wright's statement to Dr. Gough, would seem to show that it was made of what was called tool steel (approximately 1.0 carbon).18: Their intended piston ring tension is not known. Measurements of samples from the 4-and 6-cylinder vertical engines vary greatly, ranging from less than 1/2 lb per sq in. to almost 1-1/4 lb. The validity of these data is very questionable as they apply to parts with unknown length of service and amount of wear. It seems quite certain, however, that even when new the unit tension figure with their wide rings was only a small fraction of that of the modern aircraft piston engine.19:The Papers of Wilbur and Orville Wright, volume 2, Appendix.20: The Wrights apparently never applied for an engine patent of any kind. This no doubt grew out of their attitude of regarding the engine as an accessory and deprecating their work in this field. A reasonably complete patent search indicates that this particular cam device has never been patented, although a much more complex arrangement accomplishing the same purpose was patented in 1900, and a patent application on a cam-actuating mechanism substantially identical to that of the Wrights and intended for use in a golf practice apparatus is pending at the present time.a: Concurrently with the Wrights' first engine work, Manly was developing the engine for the Langley Aerodrome, and a comparison of the Wrights' engine development with that of Manly is immediately suggested, but no meaningful comparison of the two efforts can be drawn. Beyond the objective of producing a power unit to accomplish human flight and the fact that all three individuals were superb mechanics, the two efforts had nothing in common. The Wrights' goal was an operable and reasonably lightweight unit to be obtained quickly and cheaply. Manly's task was to obtain what was for the time an inordinately light engine and, although the originally specified power was considerably greater than that of the Wrights, it was still reasonable even though Manly himself apparently increased it on the assumption that Langley would need more power than he thought. The cost and time required were very much greater than the Wrights expended. He ended up with an engine of extraordinary performance for its time, containing many features utilized in much later important service engines. His weight per horsepower was not improved upon for many years. The Wrights' engine proved its practicability in actual service. The Manly engine never had this opportunity but its successful ground tests indicated an equal potential in this respect. A description of the Langley-Manly engine and the history of its development is contained inSmithsonian Annals of Flightnumber 6, "Langley's Aero Engine of 1903," by Robert B. Meyer (xi+193 pages, 44 figures; Smithsonian Institution Press, 1971)
1: An extensive bibliography, essentially as complete at this time as when it was compiled in the early 1950s, is given on pages 1240-1242 of volume 2 ofThe Papers of Wilbur and Orville Wright, 1953.
2: Max P. Baker was a technical adviser to the Wright estate and as such had complete access to all of the material it contained.
3: In the 1890s the wealthy inventor Sir Hiram Stevens Maxim conducted an experiment of considerable magnitude with a flying machine that utilized a twin-cylinder compound steam powerplant. It was developed to the flight-test stage.
4: Fred C. Kelly,Miracle at Kitty Hawk, 1951.
5: Charles E. Taylor (Charley Taylor to the many who knew him) was in effect the superintendent of and also the only employee to work in the original small machine shop. A most versatile and efficient mechanic and machine operator, he made many parts for all of the early engines, and in the manner of the experimental machinist, worked mainly from sketches. He also had charge of the bicycle shop and its business in the absence of the Wrights.
6: This is a charitable agency set up by the late Colonel and Mrs. E. A. Deeds primarily for the purpose of building and supporting the Deeds Carillon and the Carillon Park Museum in Dayton, Ohio.
7: The Science Museum expressed a desire to have these but never received them. There is a reference to them in a letter to the Museum from the executors of his estate dated 20 February 1948, but is seems rather obvious from the text that by this time the drawings mentioned by Orville Wright in his 1943 letter had become confused with those being prepared by Christman for the Smithsonian Institution. The Science Museum did have constructed from its own drawings a very fine replica which is completely operable at this time.
8: There is a third set of drawings prepared by the Ford Motor Company also marked as being of the 1903 engine and these are rather well distributed in various museums and institutions. What this set is based on has been impossible to determine but it is indicated from the existence of actual engines and parts and the probable date of their preparation (no date is given on the drawings themselves) that they were copied from drawings previously made, and therefore add nothing to them. The Orville Wright-Henry Ford friendship originated rather late, considering Ford's avid interest in history and mechanical things. This tardiness could possibly have been the result of Wright coolness—a coolness caused by a report, at the time the validity of the Wright patents was being so strongly contested, that Ford had advised some of those opposing the Wrights to persevere and to obtain the services of his patent counsel who had been successful in overturning the Selden automobile patent. If this barrier ever existed it was surmounted, and Ford spent much effort and went to considerable expense to collect the Wright home and machine shop for his Dearborn museum. The shop equipment apparently had been widely scattered and its retrieval was a major task. It is most likely that the drawings resulted from someone's effort to follow out an order to produce a set of Ford drawings of the original engine. A small scale model of the 1903 flight engine, constructed under the supervision of Charles Taylor, is contained in the Dearborn Museum.
9: Charles L. Manly was engaged in the development of the engine for the Langley Aerodrome. See also footnote to Table on page62.
10: Fernand Forest,Les Bateaux Automobiles, 1906.
11: Grover Loening, letter of 10 April 1963, to the Smithsonian Institution.
12: Assuming a rich mixture, consumption of all the air, and an airbrake thermal efficiency of 24.50% for the original engine, the approximate volumetric efficiency of the cylinder is calculated to have been just under 40%.
13: A rather thorough stress analysis of the rod shows it to compare very favorably with modern practice. In the absence of an indicator card for the 1903 engine, if a maximum gas pressure of five times the MEP is assumed, the yield-tension factor of safety is measurably higher than that of two designs of piston engines still in wide service, and the column factor of safety only slightly less. The shear stresses in the brazed and threaded joints are so low as to be negligible.
14: Rankin Kennedy,Flying Machines—Practice and Design, 1909.
15: Considerable doubt surrounds Whitehead's actual flight accomplishments, but Pruckner's engines were certainly used, as several were sold to early pioneers, including Charles Wittemann. It is probable that the specific power output was not very great, for the air-cooled art of this time was not very advanced and Pruckner had a rather poor fin design. But the change to water cooling eliminated this trouble, and the engines were most simple, should have been relatively quite light, and with enough development could probably have been made into sufficiently satisfactory flying units for that period.
16: A drawing of the camshaft is held by The Franklin Institute.
17: Baker states that the first crankshaft was made from a slab of armor plate and if this is correct the alloy was a rather complex one of approximately .30-.35 carbon, .30-.80 manganese, .10 silicon, .04 phosphorus, .02 sulphur, 3.25-3.50 nickel, 0.00-1.90 chromium; however, all the rest of the evidence, including Orville Wright's statement to Dr. Gough, would seem to show that it was made of what was called tool steel (approximately 1.0 carbon).
18: Their intended piston ring tension is not known. Measurements of samples from the 4-and 6-cylinder vertical engines vary greatly, ranging from less than 1/2 lb per sq in. to almost 1-1/4 lb. The validity of these data is very questionable as they apply to parts with unknown length of service and amount of wear. It seems quite certain, however, that even when new the unit tension figure with their wide rings was only a small fraction of that of the modern aircraft piston engine.
19:The Papers of Wilbur and Orville Wright, volume 2, Appendix.
20: The Wrights apparently never applied for an engine patent of any kind. This no doubt grew out of their attitude of regarding the engine as an accessory and deprecating their work in this field. A reasonably complete patent search indicates that this particular cam device has never been patented, although a much more complex arrangement accomplishing the same purpose was patented in 1900, and a patent application on a cam-actuating mechanism substantially identical to that of the Wrights and intended for use in a golf practice apparatus is pending at the present time.
a: Concurrently with the Wrights' first engine work, Manly was developing the engine for the Langley Aerodrome, and a comparison of the Wrights' engine development with that of Manly is immediately suggested, but no meaningful comparison of the two efforts can be drawn. Beyond the objective of producing a power unit to accomplish human flight and the fact that all three individuals were superb mechanics, the two efforts had nothing in common. The Wrights' goal was an operable and reasonably lightweight unit to be obtained quickly and cheaply. Manly's task was to obtain what was for the time an inordinately light engine and, although the originally specified power was considerably greater than that of the Wrights, it was still reasonable even though Manly himself apparently increased it on the assumption that Langley would need more power than he thought. The cost and time required were very much greater than the Wrights expended. He ended up with an engine of extraordinary performance for its time, containing many features utilized in much later important service engines. His weight per horsepower was not improved upon for many years. The Wrights' engine proved its practicability in actual service. The Manly engine never had this opportunity but its successful ground tests indicated an equal potential in this respect. A description of the Langley-Manly engine and the history of its development is contained inSmithsonian Annals of Flightnumber 6, "Langley's Aero Engine of 1903," by Robert B. Meyer (xi+193 pages, 44 figures; Smithsonian Institution Press, 1971)