DEVELOPMENT OF THE LIBERTY AND OTHER MOTORS
DEBATE IN REGARD TO ORIGIN OF LIBERTY MOTOR—LIBERTY-ENGINE
CONFERENCE, DESIGN, AND TEST—MAKERS OF PARTS—HISPANO-SUIZA
MOTOR—ROLLS-ROYCE—OTHER MOTORS
There has been more discussion of the Liberty motor than any other
motor made during the war. This was due to the publicity given to the
motor by the publication of a romantic story of the motor, issued from
Washington over the signature of Secretary of War Baker, to the effect
that the motor was conceived in a few days, and built and perfected
within a month. Of course every engineer knows that that could not
be done, and it took at least six months before the Liberty engine
was perfected, and this was long after the Creel Publicity Bureau in
Washington issued its statement.
As we have pointed out elsewhere, if the Aircraft Production Board
had taken the patterns of a standard motor like the Hispano-Suiza,
which had been flown for nearly three years under all kinds of war
conditions, and which was being built in this country, and if they
had ordered gigs, dies, and tools, and when we entered the war had
requested our engineers to follow Chinese patterns in the making of
the same, the dies, gigs, etc., could have been made at once instead of
months later, and many American-made aircraft could have been operating
over the lines when the Americans began to fight at Château-Thierry,
and not months later, as was the case. Undoubtedly this delay cost
the lives of thousands of American soldiers, and set back the Allied
victory by just so much. The failure to deliver aircraft on schedule
was the reason why General Pershing had to demand haste in the
production of machines. Regardless of the fact that the aeroplane
motor is radically different from the automobile motor, because it
must be much lighter, nevertheless automobile men were called in by
the Aircraft Production Board to design the Liberty motor, and many of
the engine-building companies that had been constructing aeronautical
motors were not consulted.
After the Liberty engine was completed a lively debate was instituted
as to which of the two companies that was represented at the designing
of the engine deserved the most credit for the job. One of the
automobile companies advertised the fact that they were responsible for
the Liberty motor, and the other company immediately replied, trying to
prove that because they had built successful motors before the war that
they were the real designers of the motor.
To be sure, no one would have objected to the construction of a Liberty
motor on the side, but to delay the construction of motors in quantity
until September, 1917, put the United States back just six months in
production, for a number of factories were already producing parts for
Rolls-Royce engines, and the Wright-Martin Company had been building
the Hispano-Suiza motor since January, 1916.
Be that as it may, the facts regarding the Liberty motor appear to
be that General Squier, E. A. Deeds, Howard E. Coffin, S. D. Waldon,
of the Aircraft Production Board, called in to consultation on May
29, 1918, E. J. Hall, chief engineer of the Hall-Scott Motor Company,
builders of a number of 4, 6, 8, and 12 cylinder aeroplane engines,
and Jesse G. Vincent, experimental engineer of the Packard Motor Car
Company, who had just completed a design and an experimental aeroplane
engine, which had never up to that time been in a plane.
Both these gentlemen were in Washington attempting to interest Signal
Corps officials in the aeroplane engine each had designed.
LIBERTY-ENGINE CONFERENCE
A five-day conference between Mr. Hall and Mr. Vincent, called by Mr.
Deeds and Mr. Waldon of the Aircraft Production Board to consider
aeroplane-engine design and production, was held. The two engineers got
together in designing a standardized, directly driven, five-bearing
crank-shaft engine of 8 cylinders, and one of 12 cylinders, with a
seven-bearing crank-shaft. After a session of twenty hours’ work in
a room at the New Willard Hotel, in Washington, during which meals
were served the two men, and both lived, worked, and slept in the
apartments of Mr. Deeds, a new 8-cylinder 230 horse-power aeroplane
engine was laid out, described, and drawings of transverse and
longitudinal sections were made by Vincent and Hall themselves. This
was the first Liberty motor designed.
On the morning of May 30, 1917, near the close of the designing
session, Mr. Vincent dictated a joint report to the Aircraft Production
Board. The salient points and a rough draft had been agreed upon the
night before. It was dated May 31, 1917, and signed jointly by E. J.
Hall and Jesse G. Vincent.
WASHINGTON, D. C., May 31, 1917.
AIRCRAFT PRODUCTION BOARD,
WASHINGTON, D. C.
_Gentlemen_: At your request we have made a careful study of the
aircraft motor situation and hasten to submit our report as follows:
In order to get this report in your hands promptly we have condensed
it as much as possible and have covered the essentials only.
In view of the fact that there are a number of good motors for
training-machines available, we have disregarded this type of motor
and have confined our attention strictly to the high-efficiency,
low-weight per horse-power type, such as is necessary at the front.
In order that any motors that are built by this country may be of
any value when received at the front, it is, of course, absolutely
necessary that their efficiency be brought up to or a little beyond
the best now available in Europe. This, of course, made it necessary
for us to know just what has been accomplished in Europe. The French
and English Commission has enabled us to obtain this information by
answering our questions very clearly and completely.
From information obtained from these gentlemen and from other sources,
we believe that the Loraine Dietrich is the coming motor in Europe.
This motor has not been built in large quantities as yet, but some
thirty had been constructed and carefully tested out at sea-level and
also at about 6,000 feet elevation. The important facts about this
motor are as follows:
Eight cylinders: 120 mm. bore by 170 mm. stroke.
Cylinders made of steel with water-jackets welded on. Motor is
direct-driven and develops 250 horse-power at 1,500 r. p. m., and
270 horse-power at 1,700 r. p. m. The weight of the bare motor is
240 kilos, or approximately 528 pounds, while the weight of the
motor complete with radiator and water is 305 kilos, or 671 pounds.
There seems to be a reasonable doubt regarding the exact weight of
the bare motor, as while the French Commission gave us the figure of
528 pounds, information from other sources indicates a weight of 552
pounds; probably some intermediate figure is more nearly correct,
but in any event the motor gives a horse-power for approximately two
pounds of weight when figured at its maximum output of 270 horse-power.
After obtaining this information and considering the matter very
carefully, we next investigated the matter of testing such a motor,
as we knew that a motor of this type could not be run at full power
for long periods of time without developing serious trouble. Here
again the French Commission gave us valuable information. They stated
that in using a motor of this type it is only run at full power for
short periods of time while climbing or fighting, and that all other
times it is run at speeds 200 to 300 r. p. m. slower. In view of the
fact that the motor is built to run under these conditions, it is, of
course, necessary to test it under similar conditions, and they stated
when trying out a new model of motor it is their practice to mount a
propeller which will just hold the motor down to maximum speed under
full throttle. The motor is then run for fifty hours, in periods of
six to eight hours each, but the motor is not run up to full speed for
more than a total of ten hours during this entire period, nor is it
run more than thirty minutes at any single time under this condition.
The other forty hours’ running is under throttled conditions, turning
the same propeller 200 to 300 r. p. m. less than maximum speed.
This information is of the utmost importance, as it enables us to
reduce all factors of safety and make possible the light-weight per
horse-power now being obtained in Europe.
After obtaining this information we immediately laid down a proposed
motor which we believe can be produced promptly in large quantity in
this country. Built carefully out of proper materials, this motor will
have approximately the following characteristics and be as good, or a
little better, than the Loraine Dietrich, which is not as yet really
available abroad.
In laying down this motor we have without reserve selected the best
possible practice from both Europe and America. Practically all
features of this motor have been absolutely proved out in America by
experimental work and manufacturing experience in the Hall-Scott and
Packard plants, and we are, therefore, willing to unhesitatingly stake
our reputations on this design, providing we are allowed to see that
our design and specifications are absolutely followed.
The motor is to be of the eight-cylinder type, with cylinders set at
an included angle of 45 degrees. The cylinders are of the individual
type, made out of steel forgings with jackets welded on. The bore is
five inches and the stroke seven inches, giving a piston displacement
of 1,100 cubic inches. The crank-shaft is of the five-bearing type
with all main bearings 2⅜ inches in diameter, and all crank-pin
bearings 2¼ inches in diameter. The connecting-rods are of the
I-beam straddle type. This motor is of the direct-driven type with a
maximum speed of 1,700 r. p. m. This motor will have a maximum output
of 275 horse-power at 1,700 r. p. m. It will weigh 525 to 550 pounds,
but we feel very sure of the lower figure. It will have a gasoline
economy of .50 pounds of fuel per horse-power hour or better; it will
have an oil economy of .04 pounds of oil per horse-power hour or
better. Complete with water and radiator, this motor will not weigh
more than 675 pounds, if a properly constructed radiator is used and
placed high above the motor.
To obtain the above-mentioned weights it will be necessary to use the
fixed type of propeller hub which has been thoroughly proved out by
Hall-Scott practice. In order to obtain the above-mentioned weights
it will also be necessary, as mentioned above, to use the very best
material, workmanship, and heat treatment.
Complete detail and assembly drawings, as well as parts list and
material specifications, can be completed at the Packard factory under
our direction in less than four weeks. We believe that a sample motor
can also be completed in approximately six weeks if money is used
without stint. As soon as the drawings, specifications, and sample
motor have been finished, complete information would, of course, be
available so that any high-grade manufacturer could either make parts
for this motor or manufacture it complete.
In laying down this design we have had in mind the extreme importance
of interchangeability, as a well-laid, comprehensive programme
which has for its base interchangeability of important parts,
such as cylinders, will speed output and reduce ultimate cost to
an astonishing extent. Europe is suffering right now from lack of
uniformity of design, but it is too late for them to change their
plan. We, however, can take a leaf out of their book and start right.
In the design which we have laid down, the cylinder, for instance,
can be used to make four, six, eight, and twelve cylinder motors. As
this is the most intricate part to make, immense facilities could
be provided to produce them in large quantities for the use of many
concerns who could manufacture the balance of the motor. Nearly all
small parts and numerous large and important ones would also be
interchangeable. This would not only speed up production but would be
of the utmost importance in connection with repairs and replacements.
A full line of motors made according to this plan would line up about
as follows:
Rated Maximum Weight per
Type Horse-power Horse-power Weight Horse-power
4 110 135 375 2.7
6 165 205 490 2.3
8 225 275 535 1.9
12 335 410 710 1.7
Respectfully submitted,
(_Signed_) J. G. VINCENT.
(_Signed_) E. J. HALL.
On June 4 Hall and Vincent finished a layout of an 8-cylinder engine,
and presented the drawings and received an order to build ten sample
engines, and on June 8 the Packard Company arranged for pattern-making,
production work, etc.
This motor after intensive work on detail drawings was put into
preliminary production. The first one was delivered to Washington,
July 3, 1917. In the making of the sample engine Mr. Vincent’s company
placed its factory organization at the disposal of the government, and
through Mr. Vincent’s untiring efforts and enthusiasm the first motor
was completed within the sixty days.
The other companies which aided in the work of building this motor were:
The General Aluminum and Brass Manufacturing Company of Detroit made
bronze-backed, babbitt-lined bearings and aluminum castings.
The Cadillac Motor Car Company of Detroit made the connecting-rods,
connecting upper-end bushings, connecting-rod bolts, and rocker-arm
assemblies. The Cadillac Company had perfected the design of
connecting-rods of the forked or straddle type, and had been using them
for several years in their 8-cylinder engines.
The Parke Drop Forge Company of Cleveland made the crank-shaft
forgings. These forgings completely heat-treated were produced in three
days, simply because Mr. Hall gave them permission to dig out the
Hall-Scott dies which were used in making the first Liberty crank-shaft
forgings.
Hall-Scott Motor Car Company of San Francisco supplied all the
bevel-gears out of its stock for the standardized line of Hall-Scott 4,
6, 8, and 12 cylinder aeroplane engines.
The L. O. Gordon Company of Muskegon made the cam-shafts.
The Hess-Bright Manufacturing Company of Philadelphia made the
ball-bearings.
The Burd High Compression Ring Company of Rockford, Ill., supplied
the piston-rings out of stock made up for the Hall-Scott line
of standardized aeroplane engines, for which it had perfected a
piston-ring.
The Aluminum Castings Company of Cleveland supplied the die-cast alloy
pistons, and machined them up to grinding, as they had been engaged in
making them for several years for the Hall-Scott line of standardized
aviation engines.
The Rich Tool Company made the valves.
[Illustration: The Martin bomber.
This plane is equipped with two Liberty engines and has many
long-distance records. It flew from Pittsburgh to Washington, a
distance of 175 miles, in 1 hour and 15 minutes. It also flew from the
Atlantic to the Pacific.]
The Gibson Company of Muskegon made the springs.
The Packard Company made the patterns and several dies in order to
obtain drop-forgings of the proper quality. It also machined the
crank-shafts.
After the preliminary tests passed by the 8-cylinder engine, August
25, 1917, Government Inspector Lynn Reynolds said “that the design has
passed from the experimental stage into the field of proven engines.”
The machine was tested at Pike’s Peak, Colorado, for altitude in
August, 1917. Reports from the battle-field decided the board to build
12-cylinder engines. Thereupon standardized parts made interchangeable
for all types of Liberty engines were detailed, and orders placed with
the various firms named to build the same. Production was started on a
large scale.
On October 17 the production of the Liberty motor started, over six
months after we entered the war.
The delivery of the first Liberty 12 was made on Thanksgiving Day, 1917.
One of the unrecorded incidents of this period concerned the
“scrapping” of $400,000 worth of semi-finished parts of an automotive
aircraft engine, which was assumed O. K., and parts had been ordered
for 250 motors. It was actually in production at the time Hall and
Vincent were ignoring practically all its features and “laying out” the
designs for the Liberty 8 and Liberty 12. It had never been tested in a
plane, and its design and all its parts were rejected.
Owing to the slowness of production due to the new gigs, dies, tools,
etc., necessary to build the engines, much criticism was directed at
the lack of shipments of Liberty engines for army air service in the
winter months of 1917.
Charged with the necessity of protecting the American army transport,
the Navy Department had first call on all air-service equipment. As
a result it received the first Liberty 12’s turned out. These were
installed in navy aeroplanes, where they did good work.
The preliminary Liberty 8 was delivered to the Bureau of Standards,
Washington, D. C., July 3, 1917, by the group of industrial concerns
named. A 54-hour test was made of a Liberty 12 on August 25 by
the Bureau of Standards. The Liberty 12 was detailed for quantity
production, and the actual work was begun, and the work done by
these companies in producing Liberty-engine parts is above praise.
It was then that the mighty energies of their splendid organizations
demonstrated the ability of American industrial life to fight the
battle behind the lines.
WAR DEPARTMENT STATEMENT
Departing from its policy of secretiveness concerning all things of a
military character, the United States War Department on May 15, 1918,
issued an authorized statement dealing with the technical features
and characteristics of the Liberty 12, then in quantity production.
This statement was published in the _Congressional Record_ of an early
subsequent date.
Secretary of War Baker in his report published elsewhere in this book
gives the following account of Liberty motors built:
PRODUCTION OF SERVICE ENGINES
In view of the rapid progress in military aeronautics, the necessity
for the development of a high-powered motor adaptable to American
methods of quantity production was early recognized. The result of
the efforts to meet this need was the Liberty motor—America’s chief
contribution to aviation, and one of the great achievements of the
war. After this motor emerged from the experimental stage, production
increased with great rapidity, the October output reaching 4,200, or
nearly one-third of the total production up to the signing of the
armistice. The factories engaged in the manufacture of this motor, and
their total production to November 8, are listed in Table 21.
TABLE 21.—PRODUCTION OR LIBERTY MOTOR TO NOVEMBER 8, 1918, BY
FACTORIES:
Packard Motor Car Co 4,654
Lincoln Motor Co 3,720
Ford Motor Co 3,025
General Motors 1,554
Nordyke & Marmon Co 433
———
Total 13,396
Of this total, 9,834 were high-compression, or army type, and 3,572
low-compression, or navy type, the latter being used in seaplanes and
large night bombers.
In addition to those installed in planes, about 3,500 Liberty engines
were shipped overseas, to be used as spares and for delivery to the
Allies.
Other types of service engines, including the Hispano-Suiza 300
horse-power, the Bugatti, and the Liberty 8-cylinder, were under
development when hostilities ceased. The Hispano-Suiza 180
horse-power had already reached quantity production. Nearly 500
engines of this type were produced, about half of which were shipped
to France and England for use in foreign-built pursuit planes.
Table 22 gives a résumé of the production of service engines by
quarterly periods:
TABLE 22.—PRODUCTION OR SERVICE ENGINES IN 1918:
Jan. 1 to Apr. 1 to July 1 to Oct. 1 to
Name of engine Mar. 31 June 30 Sept. 30 Nov. 8 Total
Liberty 12, Army 122 1,493 4,116 4,093 9,824
Liberty 12, Navy 142 633 1,710 1,087 3,572
Hispano-Suiza 180 h.p. ... ... 185 284 469
Later the Statistical Department of the War Department issued the
following. The number of planes and engines shipped by the Bureau of
Aircraft Production to depots and storehouses from the date of the
armistice to February 14:
Liberty 12 service engines 4,806
OX-5 elementary training-engines 1,261
Le Rhone advanced training-engines 994
De Havilland-4 observation planes 524
Hispano 180 advanced training-engines 343
Hispano 150 advanced training-engines 254
JN6-H advanced training-planes 174
JN4-D elementary training-planes 131
The Packard Motor Car Company made the final deliveries of Liberty
12 motors during the week ended March 21, 1919. This completes all
contracts. The following shows the number and per cent produced by
each factory:
Number P.C.
Firm produced of total
Packard Motor Car Co. 6,500 32
Lincoln Motor Co. 6,500 32
Ford Motor Co. 3,950 19
General Motors Co. 2,528 12
Nordyke & Marmon Co. 1,000 5
———
Total 20,478
THE HISPANO-SUIZA
It is evident from the records made by the German Mercedes, which
are given in another chapter, that it was the best aviation motor
in existence in July, 1914. Naturally, this motor had considerable
influence on the aeronautical engineers of the Allies. Mr. Marc
Birkright, a Swiss engineer to the Hispano-Suiza Company, automobile
builders in Barcelona, Spain, and Paris, designed the aviation motor
which now holds the world’s record for altitude—28,900 feet. When he
designed the motor he had in mind the construction of the machine-tools
necessary to build the same.
In the summer of 1915 the first motor of 150 horse-power was delivered
to France after a test of 15 consecutive hours. The next two were
tested for 50 hours, and proved satisfactory. France placed a large
order, and the Hispano-Suiza factory began production at the end of
1915. Before the end of the war three Italian, fourteen French, one
British, one Japanese, and one Spanish factory, besides 25,000 people
in America, were producing Hispano-Suiza engines.
The motor had great success in the single-seater fighters flown by
such men as Captain Georges Guynemer, Lieutenant Fonck, Nungesser, and
dozens of other aces.
With the exception of increasing the horse-power from 150 to 180, 200,
300, very few changes were made in this motor in this country.
Four hundred and fifty engines were ordered by the French Government
of the General Aeronautic Company of America early in 1916. When the
Wright-Martin Aircraft Company was formed in September of that year,
less than 100 motors had been delivered. At the end of July, 1917,
1,000 motors were on their books.
From July, 1917, the American factory concentrated on the 150
horse-power engine. The Wright-Martin Company had to build its own
plant for aluminum castings for the engine. In November of that
year the company was ordered to build 200 horse-power engines, and
later the 300 horse-power was ordered. In May, 1918, the French and
British Governments decided to use the 300 horse-power motor in
large quantities, and by October the factories of the company in New
Brunswick and Long Island City were tooled up to produce 1,000 motors
a month, which represented a $50,000,000 order. Early in the spring of
1918, 15 motors a day were produced, and in August of that year the
company was committed to a schedule of 30 engines a day.
THE ROLLS-ROYCE MOTOR
“There is no doubt,” says _London Motor_, “that the conception of
the Rolls-Royce aeronautic engine is extremely good, but no one will
gainsay the fact that the care exercised in manufacture and the
elaborate operations through which the various parts have to pass are
in part the reason for its success. This refinement necessitates the
passing of certain parts through fifty or sixty operations that might
be easily carried out in a comparatively small number if superfine
finish were not desired or required.
“The Rolls-Royce ‘Eagle’ engine, originally designed as a 200
horse-power unit, developed 255 horse-power on the first brake test.
Diligent research and experiment were pursued with extraordinary
results, as will be seen in the following record of official brake
tests, all made without any enlargement of the dimensions or radical
alteration in design. A 12-cylinder engine, 4½-inch bore by
6½-inch stroke, developed in March, 1916, 266 horse-power at
1,800 R. P. M. By July the power was increased to 284 horse-power;
nine months from this date, in September, 1917, it had risen to 350
horse-power, and in February, 1918, 10 more horse-power was added,
making the total 360 horse-power. In addition to the ‘Eagle,’ a smaller
engine giving 105 horse-power at 1,500 R. P. M. was turned out under
the name of the ‘Hawk.’
“The ‘Eagle’ engine was used in the large Handley Page machine, and
in the successful long-distance bombing raids into Germany. In 1916
another engine for fighting planes was added to the list, under the
name of ‘Falcon,’ and was almost exclusively used in the Bristol
fighting plane. The increase in the power developed by the ‘Falcon’
engine, which has a 4-inch bore, was as follows: April, 1916, 206
horse-power at 1,800 R. P. M.; July, 1918, 285 horse-power at 2,000 R.
P. M.
“From the stamping-plant through the machine, gear-cutting, and
grinding shops and welding department, the care with which each engine
is turned out is apparent. Take apart a cylinder which has a stamped
sheet-metal water-jacket welded externally, and the original billet is
found out of which the cylinder was made, but reduced almost by half
when it is ready to receive the valve cages, and during the process
of removal of the metal and forming into proper shape the piece is
subjected to several heat treatments so as to bring the metal to that
stage of perfection needed for the work it has to perform. The elbow
cages that are fitted to the cylinders might be cast and cored, but
the valve cage is an actual solid stamping, and the right-angle bend
through the elbow has to be bored out by special machines.
“One point illustrates the care in the choice of metal and the
multifarious operations through which each part has to pass. A
crank-shaft stamping with extension piece on the rear and about one
foot long is cut off, and test pieces of this metal, properly numbered
with each crank-shaft, are passed through the same treatment as the
crank-shaft itself, and then subjected to minute examination by highly
skilled engineers. The actual manufacturing side of the work would
naturally be very similar to the manufacture of a car engine, but one
obtains a better perspective of what an engine is subjected to by
passing from the erecting and manufacturing shops to the engine-testing
shop, where the ear-splitting reports from the open exhausts of a
number of engines being tested at the same time are heard. Here one
sees how dissimilar the aviation engine is from the car engine. It is
almost impossible, without having actually witnessed it, to picture
to oneself a 12-cylinder engine running at 2,200 R. P. M. against a
brake test. As the exhaust ports are on either side of the engine, the
cylinders being placed in the form of a V, it is possible, by passing
on either side, to look into the combustion-chamber and see the valves
rising and the spit of the exhaust, and, what is almost incredible,
that the exhaust valves are actually red-hot and run in this condition
for hours. Little wonder is it that the valves have to be made of
superfine material and of particular form.
“The variation in the color of the flame of the exhaust, due to strong
and weak mixtures, makes it quite possible to test the good running of
an engine by the color of its exhaust. The strength of the mixture has
necessarily to be altered according to atmospheric conditions and the
altitude to which the pilot desires to climb.
“No doubt airplane-engine practice of the last four years and the
advance that it has made will be reflected in a very marked degree
in the automobile, not necessarily by fitting large airplane engines
in cars, but by applying to car practice the knowledge that has been
gained in manufacture.
“The Rolls-Royce works had in 1907 an area of 5,312 square yards,
and during the war this was increased to 67,935 square yards. At the
present time the payroll is somewhere in the neighborhood of 8,650.”