Power-plant laboratory standard test methods and computations (Power Plant Section)

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Auburn University libraries
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MAT$}1IEL DI V! ION REPOR:T:-, :S:E:-R-I-A-L:: -N~o~.- 2-3-4=3- --:~-=----'
AIR CORPS INFORMA "FlON CIRCULAR
PUBLISHED BY THE CHIEF OF AIR CORPS, WASHINGTON, D. C.
Vol. VI November 1, 1927 No. 589
POWER-PLANT LABO RA TORY STANDARD
TEST METHODS AND COMPUTATIONS
( POWER PLANT SECTION)
Prepared by Robert Insley
Materiel Division, Air Corps
Wright Field, Dayton, Ohio
March 24, 1924
Revised March 12, 1925
UNITED STATES
GOVERNMENT PRINTING OFFICE
WASHINGTON
1927
Ralph Brown Draugh n
UBRARY
MAY 2 8 Z013
Non·Oepoitory
Auburn University
C E UTIFI CATE: By direction of the Secret ary of War the matter contained
herein is published as administrat ive information and is required for the proper
tra nsaction of the public business.
(n )
INDEX
hp hp
General instructions _________ ______________ _ 1 Spark -p lug tests __________________________ _
General instructions for operating engines ____ _ 1 Fifty-hour en du ranee tes t ___ ________________ 8
Standard methods of taking test readings _____ _ 1 Carburetion run__ ____ ___ ______________ __ ___ 9
Method of checking scales __________________ _ 3 Carburetor head test____ ____________________ 10
Instructions for weighing engines ____________ _ 3 Carburetor flight test_ _____ _________________ 11
Full power run ___ _____________________ ____ _ 3 Instructions fo r repairing log sheets_ __________ 11
Propeller load run _________________________ _ 4 Formulre and calculations_____ ______________ 12
Friction horsepower run ____________________ _ 4 Instructions for the preparation of reports___ __ 13
Compression pre sure run __________________ _ 5 Propeller load curves_ __________ ___ ___ __ _____ 14
One-hour foel and oil consumption run __ _____ _ 5 Scale checking form___ ______________________ 15
Routine engine test_ __ ___ ___ _____ ___ _______ _ 5 Standard log sheet__ ________________________ 16
Performance limits for routine engine tests __ _ _ 7 General log sheet___ ____________ ____________ 17
Water-pump capacity tests ______ ____ _______ _ 7 Routine test log sheet_______________________ 18
Oil-pump capacity tests ____________________ _ 7 Carburetor test log sheet__ ______ ________ ____ 19
(III)
POWER~PLANT LABORATORY STANDARD TEST METHODS
AND COMPUTATIONS
GENERAL INSTRUCTIONS
The general foreman is directly responsible for the
installation of the engine and laboratory apparatus. to
be used in connection with all tests. He is responsible
also for checking of the dynamometer, fuel and oil
scales before each test is started. Instructions for
change in apparatus or equ ipment must be issued to
him only. o more than minor modifications may
be made without his approval. The general foreman
should also be notified as oon as possible after the
completion of the test or any series of runs so that he
may make arrangements for changes in set-up and
reassignment of laboratory personnel. Stop watches
and special instruments are kept in the general office
under the supervision of the office manager and are
i sued to engineers and dynamometer operators on
check or memorandum receipt. Persons to whom
such material is issued will be held responsible for its
care until returned. Any failures or inaccuracies of
such instruments should be reported to the chief of
the laboratory immediately so that repairs or replace­ments
may be made promptly.
Before starting the test the engineer should carefully
inspect the apparatus to detect any errors in in stalla­t
ion and to be sure that all necessary instruments are
provided and properly adjusted. Any changes of test
procedure or serious difficulties with laboratory appara­tus
which are likely to affect the test program should
be taken up with the chief of the laboratory so that
he may make proper accommodation in the general
laboratory program.
A complete description of the Power Plant Laboratory
has been issued under the title " D escription of t he
Power Plant Laboratory"-Engineering Division Re­port,
Serial No. 1987.
GENERAL INSTRUCTIONS FOR OPERATING
ENGINES
All new or o~erhauled engines must be thoroughly
"run in" before test runs a re started. The general
foreman will specify the "running in " required for
each engine and will decide in all cases whether or not
the condition of t he engine is satisfactory for test.
Engines should never be started or stopped abruptly
unless the nature of the test requires it or emergency
makes sudden stops nece sary . The rapid heat.ing
and cooling of parts resulting from abrupt starts or
stops is rather severe. Engines should not be run at
full speed or full throttle until the oil has been heated
sufficiently to assure circulation. It is ordinarily
advisable to allow the temperatu re to ri e above 100°
F. before the test is started. To clear the fuel system
and to prevent accidental starts, etc., the engine
should always be stopped (except in emergency) by
hutting off the fuel.
Before starting any test, the full power and fuel
consumption of the engine should be checked to
detect any inaccuracies in assembly or adjustment.
During this check run, the tachometer, thermometers,
pressure gauges, manometers, and other in struments
should also be checked.
STANDARD METHODS OF TAKING TEST
READINGS
The following methods of taking test readings have
been adopted by the power plant laboratory as the
most accurate readily applicable. In taking readings
the operating conditions should be held constant for
several minutes before any reading is attempted in
order to permit the apparat'us to "settle down" com­pletely
and to eliminate distortions due to momentary
variations.
Log sheet forms obtainable in the general office are
shown at end of text.
REVOLUTIONS PER MINUTE
In adjusting the speed on test the tachometer indi­cator
may be followed. Actual readings of revolu­tions
per minute, however, should be made with the
revolution counter by noting the counter difference
for a given interval of time, ordinarily one minute,
measured by stop watch. To avoid errors, counter
readings should be recorded d irectly on the log sheet.
BRAKE LOAD
Not less than two readings of brake load should be
made for each setting.
WATER AND OIL TEMPERATURES
Water and oil thermometers should be placed as
near as possible to the inlet and outlet connections of
the engine. Standard fitting for mercury thermom­eters
are incorporated in the lines at each dynamom­eter.
For particular accuracy, however, for heat
rejection determinations and the like, electric resistance
thermometers measuring differential or direct tem­peratures
are available. These thermometers should
be very carefully installed to avoid distortion of
readiLgs by radiation from water lines, etc. In read­ing
water temperatures the observer should be careful
to take no readings while any considerable adjustment
of the water temperature is being made.
(1)
I - -- ---------------
OIL PRESSURE
The oil pressure is determined by standard pressure
gauge on the instrument board.
AIR TEMPERATURE
Wherever possible conditioned air should be used
on engine tests. The temperature of the conditioned
air should be automatically maintained within 2° of
60° F. at all times. If it is not, the general foreman
should be notified so that adjustments can be made.
Air-temperature determinations should be made with
mercury thermometers in the carburetor air pipe as
close as possible to the engine.
INDUCTION-SYSTEM PRESSURES
Induction-system pressures should be determined by
means of mercury or water manometers. For com­parative
purposes standard induction system pressure
readings will be taken at the cylinder elbow of the
intake manifold branch farthest from the carburetor
(in symmetrical manifolds the manometer fitting will
be located in the rear branch), at the intake manifold
uptake directly above the throttle barrel, and in the
float chamber of the carburetor. In using the single
column mercury manometers the level should be ad­justed
before each reading to insure accurate results.
Note should be made as to whether there is water or
gasoline on the mercury column. For the float cham­ber
depression reading a water manometer should
be used.
FUEL CONSUMPTION
Three methods are available for measurement of
fuel consumption-the tank scales by which the weight
of fuel consumed rri.ay be determined directly, volumet­ric
gauges by which a given volume of fuel may be
timed, and Brown and Barlow flowmeters which indi­cate
directly the volumetric rate of fuel flow. In
reading either the scales or the volumetric gauge the
time required for the consumption of a given quantity
of fu el must be determined. The flowmeter measures
the rate of fuel consumption directly. The bulbs of
the volumetric fuel gauge have capacities as indicated.
They have been calibrated, however, for fuel with a
specific gravity of 0. 710. It is important when meas­uring
fuel consumption with either the volumetric
gauge or the flowmeter that the proper correction be
applied for specific gravity. Care should also be
taken to see that too great a variation of fuel head is
not introduced by the position of the volumetric gauge.
Lines have been painted on the gauge boards and ways
to assist in maintaining proper fuel head . When the
volumetric gauges are used the time interval should
not be less than 90 seconds. A similar accuracy
with the tank scales requires a reading of about five
minutes.
In specifying mixture control positions for fuel
readings "full rich" and "full lean " will be regarded
as the richest and leanest settings possible with the
given control. "Best setting" or "best" is setting
which gives the leanest mixture on which the engine
will just hold maximum power. The leaning should
2
not cause a drop in power of over Y2 of 1 per cent.
The "best setting" should be determined very care­fully
for there is sometimes considerable lag in the
engine's response, and several settings may be neces­sary
before the " best position" is actually reached.
OIL CONSUMPTION
The rate of oil consumption can be determined satis­factorily
only during runs of one hour or more duration.
Before readings are taken the engine should be run
at the required speed and load for not less than 10
minutes to permit the oil circulation to become uni­form.
During the run all operating conditions, espe­cially
speed, water temperatures, and oil temperatures,
must be held constant. Readings of the oil scales,
engine speed, brake load, water and oil temperatures,
and oil pressure should be recorded every 10 minutes
throughout the run. For the best results the quantity
of oil in the pipes between tank and engine should be
kept as small as possible.
COOLING AIR VELOCITY
Cooling air velocity in air-cooled cylinder tests is
measured by a fixed air-speed indicator fitted at the
mouth of the cooling air duct. Where greater accu­racy
is desired traverses of the mouth of the duct may
be made with a portable indicator.
CYLINDER TEMPERATURES
Cylinder temperatures are measured whenever
possible by means of thermocouples embedded in the
metal ordinarily at the hottest point of the head. A
potentiometer is used to indicate the temperature at
the thermocouple. When it is impossible to embed
the couple in the metal or when an exploration of the
cylinder is desired, a "contact " type of thermocouple
is used. Care must be taken when using thermo­couples
with millivoltmeters and uncompensated
potentiometers to correct for the cold junction tem­perature
by adding the cold junction temperature to
the indicated temperature. In connecting the ther­mocouples
to the in strument by leads of the same
materials as the thermocouples precautions must be
taken to insure that like leads are connected together
at intermediate junctions to avoid cross compensation.
SPARK ADVANCE
Unless otherwise specified, the spark advance should
be determined by means of a rotary spark advance
indicator. In case the spark advance is determined
by the position of the control lever on the graduated
sector the positions for full advance and full retard
must also be recorded. The position of best spark
advance is minimum spark advance which will give
full power.
THROTTLE POSITION
The throttle position determination is a reading of
the position of the throttle control lever on its graduated
sector. This reading is obviously valueless unlesS"
the sector positions for full open and closed throttle
are also recorded.
I
J\IlXTORE CONTROL POSITION
The mLx.ture-control position determination is a
record of the posit ion of t he carbureter mixt ure-control
lever on its graduated sector. This record also should
be accompanied by record on t he log sheet of the po i­tion
for f\Jll rich and full lean mixt ure.
METHOD OF CHECKING SCALES
Dynamometer, fu el, and oil scales should be checked
before every test. The following method have been
adopted, and scale checking forms, Engineer Division
Form 736, provided for t hat operation. The scale
checking form should be filled out and t urned in for
approval to the chief of the laboratory before the test
is started.
Dynamometer scaZes.-vVhenever possible t he dyna­mometer
scales should be checked with t he engine di -
connected from the a rmature. The 63-inch checking
arms should be firm ly clamped on the field housing
perpendici1lar to the dynamometer haft and with t he
two ends eq uidistant from t he floor. The dynamome­ter,
linkage, and exposed scale mecha nism should be
carefully inspected to detect any interference with free
movement of the dynamometer or linkage or any im­proper
ad justment of the Unkagc. Any defects noted
should be corrected before the checking is started.
Starting with the scale side checking arm, lift the
arm until about 100 pounds load is recorded on the
scale. Release t he load gently and record in the "UP"
column on the sheet the scale reading when the h and
comes to rest. Repeat the operation, depressing the
arm to 100 pounds load and releasing it gently and
record the scale reading at rest in t he" DOWN " column.
These up and down loads should be released so gent ly
that t he scale hand moves continuou ly in one direction
to t he poin t of rest without oscillating. Attach one
50-pound weight to the scale side checking arm and
reduce the load by about 100 pounds by lifting the arm.
Release the arm gently and record the reading of t he
hand at rest iu the "or" column. Repeat the operation ,
increa. ing the load by depressing t he arm, and enter
t he reading in the " now " column on t he sheet. Con­tinue
in t his manner adding one 50-pound weight at a
time until the scale hand has covered the range to be
used in the te t.
Remove all the weight from the scale side checking
arm and repeat the procedure on the opposite arm.
If the scales show an average error on either side
of more t han 1 per cent, the genera l fo reman should be
notified so that adjustments can be made. After the
adjustments have been completed t he scale checking
operation must be repeated. Only in emergency, and
then only when t he scales appear to be in good mechani­cal
condition, may a caUbration curve be drawn by
which to correct the tes ~ readings. Io general no test
should proceed un t il the scales check satisfactorily.
Fuel and oil scales.-The fuel and oil scale are
checked by adding standard test weights to the scale
platform, ascending to the capacity of the scales and
descending to zero. The readings as each weight is
added or removed should be recorded on the log sheet.
The allowable error in th is check al o is 1 per cent.
3
INSTRUCTIONS FOR WEIGHING ENGINES
1. For the purpose of determining engine weight the
basic engine will include the following acce sory parts,
and whenever possible (unless otherwise specifically
instructed, as in contracts, etc.) t he dry weight will be
so quoted :
Carburetors.
Air intake stacks.
Water pump.
Oil pumps.
Ignition system (inclu ding coils if separate) .
Generato r (when an in tegral part of the ignition
system).
Prop eller hub and bolts.
Gun ynchronizer drives.
Any piping, fittings, controls, etc., supplied by
the manufact urer and obv iously part of the
engine unit.
2. The following parts a re not to be consid ered part
of the basic engine, and when t hey a ccompany the
engine they should be weighed separately and t heir
weights quoted as accessory items:
Fuel pumps.
Exhaust pipes or fla nges.
Generators (part of t he basic engine only when
an integral part of the ignition sy tem) .
Starters.
Switches.
Voltage regulators.
External pr-ima ry and starter wiring, piping, or
controls.
Primer lines and fi ttings.
Starting magneto.
Miscellaneous items obviously not a part of the
operating engin e.
3. Whenever, for a ny rea on, the basic engine differs
from that described in pa ragraph 1 the parts included
in the weight should be specifically described. Those
items, weighed separately, should be completely identi­fied
(by type number, manufacturers' name, etc.) in
listing their weights.
4. When making engine weight determinations every
precau t ion must be taken to assu re t hat t he engine
contains as little as possible of oil and water, that the
zero weight is subt racted from the total, and that the
scales are accurate. (The most recent cale checking
sheet should not be more t han 2 months old .)
THE FULL-POWER RUN
The full-power run is made to determine the full
throttle horsepower and fu el consumption of the
engine over a range of speeds likely to be encountered
in service or of interest for purposes of design or
comparison .
A complete full-power run consists of two full­power
curve determinations, one at f'ull rich and one
" best " setting of the carburetor mixtu re control,
taking a complete set of readings at each 100 revolu­tions
per minute over a speed range from 400 revolu­tions
per minute below to 200 revolutions per minute
above normal speed. " Best setting " of the carburetor
mixture cootrol is t he leanest setting at which the
4
engine will hold full power. A brake load lower than to give maximum power and the carburetor mixture
one-half of 1 per cent below maximum will not be control set at "best position ." The instructions for
considered full power. At each speed the spark obtaining "best setting" of the mixture control are
advance should be set at the minimum advance given under the description of the full-power run,
required to give maximum power . Conditioned air page 3. The throttle and brake load only are to be
to the carburetors at approximately 60° F. should be adjusted to reduce speed and power. The full-power
used for all full-power runs. The temperature of the spark and mixture control settings should be retained
cooling water leav ing the engine will be maintained as throughout the propeller load run .
closely as possible at the point specified by Air Corps The full set of readings to be taken at each speed
or the manufacturers' ia structions. during the propeller load run consists of the following:
No readings should be taken until the engine has Revolution counter, one minute.
settled down to uniform operation at each setting. Brake load, before and after other readings.
Tho quantity of fu el used for determination of fuel Fuel consumption, for a period not less than 90
consumption should be such that the reading covers a seconds.
period of not le s than 90 seconds. A full set of Cooling water temperatu re, in and out.
readings required at each point on the power curve Oil t~mperature, in and out.
consists of the following: Oil pressure.
Revolution counter, one minute. Carburetor air temperature.
Brake load, before and after other readings. Intake manifold depression.
Fuel consumption, for a p eriod not less t han 90 Carburetor float chamber depression.
seconds. Spark advance.
Cooling water temperature, in and out. Throttle position.
Oil temperature, in and out. Mixture control position.
Oil pressure. In a ddition, all information called for on t he log
Carburetor air temperature. sheet, Engineering Division F orm 737 A should be
Intake manifold depression. provided. '
Carburetor float chamber depression. The propeller load run should be repeated if any of
Spark advance. the points obtained fall any distance from the curve
Throttle position. faired through the other points. The curve should
Mixture control position. be plotted at least in rough fo rm before the engine is
In addition, all information called for on the log removed from the te t stand .
sheet, Engineering Division Form 737 A, should be
provided.
If any point or points on the . full -power curves
obtained from this t est appear at all doubtful the run
should be repeated. The curve, therefore, should be
plotted at least in rough form before the engine is
removed from the t est stand.
THE PROPELLER LOAD RUN
The propeller load run is made to observe the per­formance
of the engine under conditions of speed and
power approximating those encountered in service.
The propeller load run starts at full-power normal
speed. Readings are taken at normal speed and at
speeds reduced by 100 revolutions per minute incre­ments
from normal speed over a range of at least 500
revolutions per minute, preferably 600 revolutions per
minute. At each speed the throttle should be so
adjusted that the horsepower varies as with propeller
load directly as the cube of the speed and the brake
load, therefore, as t he square of the speed. Curves in
Figure 1 showing the variation of brake horsepower
and brake load with engine speed in per cent may be
used in computing brake loads. In tests of geared
engines the engineer must be careful to avoid errors
resulting from confusion of engine speeds and propeller
speeds and engine and propeller torque.
The propeller load run should be started at full
throttle, normal speed of t he engine and readings
taken there and at each 100 revolutions per minute
below that speed, covering a range of at least 400
revolut ions per minute. At full t hrottle, normal
speed, the spark and throttle controls should be set
THE FRICTION HORSEPOWER RUN
The fric t ion horsepower of an engine is the power
required to overcome its mechanical friction and to
pump the mixture t hrough the engine. It is measured
at the dynamometcr by determ ining the power re­quired
to drive the engine at a specified speed with full­open
throttles, fuel and ignition shut off, and normal
water and oil temperatures.
In order to reproduce as closely as possible actual
operating temperatures, the engine must be thoroughly
warmed up under its own power before starting the
friction hor epower run and the friction run started
with least possible dela.v after the "warming up"
has been completed. Readings at each speed should
be taken rapidly as soon as engine operation has become
steady and the first readings repeated immediately
after the last to check any variations in running con­dit
ions. It is essential that oil and water tempera­tures
be maintained as nearly constant as possible
during the friction horsepower run.
The fri ction horsepo,rnr run should cover a range
of speeds from at least 400 revolutions per minute
below to 200 revolutions per minute above normal
peed. Readings should be taken at every 100 revolu­tions
per minute throughout the range. A complete
set of readings for the friction horsepower run consists
of the following: .
Speed by tachometer (to save time, counter
readings will not be taken; the tachometer
should have been carefully checked, however).
Friction load, before and_after other readings.
Water temperature, in and out.
Oil temperature, in and out.
Oil pressure.
Carburetor air temperature, average for the
run .
THE COMPRESSION PRESSURE RUN
For comparative purposes, the standard compres­sion
pressure run has been established as the deter­mination
of cylinder compression pressures with the
engine " motored " at 120 revolutions per minute with
full-open throttle, fuel and ignition off, and normal
operating water and oil temperatures. The compres­sion
pressure is measured with a Crosby indicator
with hand-operated drum. For determination of the
condition of the engine the comprei;:sion pressure of all
the cylinders should be determined. For comparison
of two engines (in good condition) of different types
the compression pressure of not less than three cylinders
of each bank should be measured.
THE ONE-HOUR FUEL AND OIL CONSUMPTION
RUN
The purpose of the one-hour fu el and oil consump­tion
run is to determine accura_tely the normal-speed
full-throttle fuel and oil consumption of the engine.
The run should be made at full throttle, normal
speed of the engine (mixture control at "best setting")
with water and oil temperatures carefully maintained
within manufacturer's or Air Corps limits. No read­ings
should be taken until all operating conditions
have become uniform. The engine operation will
probably not become uniform in much less than 10
minutes running at full throttle, normal speed . A
complete set of readings should be taken at the start
of the run and every five minutes thereafter. If it
becomes necessary during the run to replenish fuel
or oil, note of that fact should be made on the log
sheet and the exact amount of added fuel or oil recorded.
The engine operation should be carefully observed
throughout the run and any indication of unsatis­factory
condition recorded . Success in obtaining con­sistent
oil-consumption measurements depends on
maintaining uniform operating condit ions-constant
water and oil temperatures, oil pressures, and engine
speed.
The complete set of readings required every five
minutes include the following:
Speed counter, progressive reading.
Brake load .
Fuel consumption, progressive scale reading.
Oil consumption, progressive scale reading.
Cooling water temperature, in and out.
Oil temperature, in and out.
Oil pressure.
Carburetor air temperature.
Intake manifold depression.
Spark advance.
Mixture-control position.
In addition, all information called for on the log
sheet, Engineering Division Form 737 A, should be
supplied.
67329-29--2
5
THE ROUTINE ENGINE TEST
The routine engine test is conducted to prove the
acceptability of the engine for flight service. All
engines overhauled at the Engineering Division must
pass this or an equivalent test before they are approved
for service.
The routine engine test is conducted under the super­vision
of the Chief of the Engine Liaison Branch and
approval of the engine for release is given by him. He
is, therefore, the final authority in all decisions relative
to routine engine test or final inspection. No deviations
from the routine test procedure here described should
occur ·without his direct approval .
The routine engine test may be performed at either
a torque stand or a dynamometer. If the test is con­ducted
at a dynamometer, conditioned air should be
supplied to the carburetors . The following is the
standard test procedure (a log sheet form is included):
1. Preliminary inspection.-Record expenditure order
number, engine model, and number on log sh eet.
(a) Test compression of each cylinder roughly by
turning engine slowly.
(b) Check carburetor flooding.
(c) Inspect for water and oil leak.s.
(d) Record carburetor setting 011 log sheet.
2. Running in.-The engine should be run in under
its own power at ligh t load for a period specified by the
general foreman, varying according to the number
and character of new parts in the engine. The speed
and load for the running in will a lso be specified by the
general foreman, but ordinarily the period will start
at idling speed and gradually increase to normal speed
at the encl of the run. During the running-in period
the oil pressure should be adjusted with thoroughly
warm oil to specified idling and normal speed pressures;
120° F. will be considered t he standard temperature
for pressure arljustment. The following readings
should be taken and reco rded on the log sheet every
15 minutes during the running-in period:
Time.
Tachometer indicated speed.
Torque load.
vVater temperatures, in and out.
Oil temperatures, in and out.
Oil pressure.
Carburetor air temperature.
3. Idling rnn.-For the idling run the throttles
should be set so that the engine fires uniformly with
fully advanced spark at not more than 350 revolutions
per minute. (If the engine is tested at a dynamometer
the brake load should not exceed 20 pounds.) The
idling run is of 15 minutes duration. Every 5 mi.Lrntes
readings should be made of counter, indicated revolu­tions
per minute, water and oil temperatures, oil pres­sure,
fuel scales, and carburetor air temperature.
Record should be made of the cylinders " missing"
during the run and of the number and location of
plugs cleaned or replaced after the run. The engine
should be run at full throttle at the encl of the idling
nm and its behavior noted. The whole purpose of the
idling run is to detect overoiling and plug-fouling
tendencies. Those records, therefore, a re very
important.
4. Preliminary runs.
(a) Oil-pressure check run.- With oil thoroughly
warm (120° F.) check full t hrottle and idling p ressures.
(b) and (c) Acceleration.- With fully advanced spark
t he acceleration both rapid and slow should be tested
particularly for the purpose of discovering " flat spots"
resulting from improper carburetion. All " flat spots"
must be eliminated before the engine can be approved
for release.
(d) Synchronization of ignition breakers.-To dis­cover
any improper synchronization of ignition breakers
the engine should be operated at full t hrottle, normal
speed, first on all and then on single switches, without
load adjustment. The comparative speeds on single
switches indicate the degree of ignit ion breaker syn­chronization,
provided all plugs a re firing p roperly.
5. Full throttle runs.-When the preliminary runs
have been com'pleted satisfactorily the following runs
should be made at full throttle normal speed, best
spark advance:
(a) Five-minute run with mLxture control at "full
rich ."
(b) Five minute run with mixture control at "best
settlng."
(c) Dynamometer test, fiv e-minute run at 200 revolu­tions
per minute above normal speed "best setting."
(d) Dynamometer test, five minute run at 200
revolutions per minute below normal speed "best
setting."
(c) R ecord of revolut ions per minute by tachometer
at " f'ull lean" mixture control setting. When testing
at the dynamometer t his determination should be made
without change of dynamometer load adjustment
from best etting load.
The following readings should be taken during t he
full throttle runs:
Time, start a nd stop.
E ngine revolutions per minute, by cou nter at
beginning aud end.
Torque load, at beginniug and encl .
\¥ater temperatures, in and out.
Oil temperatures, in and out.
Oil pressure.
Carburetor air temperature.
Intake manifold vacuum.
Fuel scale readin g, before and after.
6. One-hour ntn.- As soon as the full throttle runs
have been completed a one-hour run should be made
at 90 per cent normal speed on propeller load at best
spark advance and mixture control position. The
following readings should be taken every 15 minutes:
Time.
Engine speed by progressive counter readings.
T orque load.
Water temperatures, in and out.
Oil temperatures, in and out.
Oil pressure.
Carburetor air temperature.
Manifold vacuum.
6
Fuel scales, progressive readings.
Oil scales, progressive readings.
Note should be made of any cylinders showing a
tendency to overoil during the one-hour run. At the
end of the run the engine should be stopped very
gradually to prevent strains and valve warpage.
7. Compression pressures.- When the engine is cool
the compression pressures of all the cyli nders should be
judged by "feel " or leakage sound when turning the
engine by hand, by the sound of suddenly opening the
exhaust valve (with wooden or rawhide mallet) at top
center, or when a careful determination is required, by
motoring the engine with the dynamometer at 120
revolutions per minute and mea uring the compression
pressure with a Crosby gauge. Pressures should be
recorded as "good," "fair," or "poor" when estimated
and in pounds per square inch for Crosby gauge t ests.
If any cylinder has lost compre sion the engine must
be returned to the shop for repair a nd the test rerun
as described in paragraph 9.
8. Final checking.-If the cylinder compression
pressures are satisfactory and the engine power, fuel
and oil consumption results meet the requirements of
the table on page 7, the engine will be returned to the
shop for final checking. The final checking consists
of the following operations:
(a) Determination of valve timing.
(b) Determination of valve tappet clearances.
(c) Determination of ignition breaker timing.
(d) Determination of ignition breaker gap.
(e) Inspection of breaker synchronization .
(f) Cleaning carb uretor strainers.
(g) Cleaning oil strainers.
(h) Inspection of accessory equipment.
(i) Preparation for temporary storage, if required
(j) Covering exhaust ports and air intakes.
9. Renm.- If the routine test discloses any unsatis­factory
conditions which require only partial overhaul
of the engine the follo\,·ing rerun will be required after
repairs have been made:
(a) Five minutes full t h rottle, normal speed, best
spark advance, best mixture control position.
(b) One-half hour at 90 per cent normal speed on
propeller load under conditions similar to the
one-hour run.
The engine during this rerun must meet the require­ments
given in Table 1. If the trouble has been suffi­ciently
serious to require a complete overhaul, the
entire routine test must be repeated.
10. Engine tags.-Engines which have passed thti
routine engine test satisfactorily will be identified with
a tag marked "0. K. for flight." On the tag will be
written a lso the foUowing data:
Full throttle revolutions per minute.
Fu ll throttle horsepower (corrected).
Fuel consumption, gallons per hour at-
Full tlu·ottle, full rich.
Full throttle, best setting.
One-hour run.
Oil consumption, gallons per hour for one-hour
run.
TABLE !.- Performance limits for routine engine tests
~ 'rorq ue stand ''O , • .a '., '.,
3l ·§~ g§ <l'O <l'O
oi:i 8§
~ -0 a ''O "::>
§ .,, ... ~~~ ~& -o " z' : :s 8. i:i .. 0 "' -., ~., ~oa>- ...
Run 8.!3 S.~:3 ~'g Sas oil: a ll: la o:1 ... ~ <l ...
e~ ·-~ ~ "'8. 0 s8.0:35 :3 5 ::i~o
B a5 a ... ., a"'"' a o..o:1 8 0.,Q a a.,,
·- 0.
<l "' ... .,
>< .!3 ·- ~·- o i... ~s~-~~;p -s ... d~ "_g <l::>"'
~ ::E ::E r:i·-.Ol ·;:E"'°' ~., 0. ::E"'
- - - - ------------
Liberty 12:
.l''ullD thor o__tt_l_e_ ____ _• F.R. 295 1,650 385 410 230 210 ---- --
B. P. 295 1, 650 385 410 210 200 ------ 90 per cent
Wri~~~=------- B. P. 240 1, 485 ----·- --- --- liO -- --- - 12
FullD thor o__t_tl_e_ _._.•_ F.R. 140 I, 750 190 195 ! 115 100 -- ---- B.P. 140 1, 750 190 1951 100 90 --- --- 90 per cent
speed ________ B.P. 113 I, 575 ------ ------ 80 ------ 6
Wright f:
Full tnrottle ___ F.R. 140 1,400 150 155 90 82 ------ Do ________ B.P. 140 1,400 150 155 82 75 ------ 90 per cent
speed ________ B.P. 113 1,260 ------ ------ 65 ------ 5
WATER PUMP CAPACITY TESTS
Two methods of test are employed for measuring
the water-pump capacity-test of the pump when
pumping through the engine cooling system, and test
of the pump with free outlet and inlet.
PUMP CAPACITY PUMPING THROUGH ENGINE
F:or this test the engine is installed at the dyna­mometer
and run through the same range of speed
covered by the full-power runs, ordinarily from 400
revolutions per minute below normal speed to 200
revolutions per minute above normal speed. Water and
oil temperatures are maintained in accordance with Air
Corps or manufacturer's instructions. The engine
is run at full throttle, best park advance, best mixture­control
setting at each speed. It is allowed to run at
each speed several minutes before readings are started
in order to permit all conditions to become constant.
At each 100 revolutions per minute increment of speed
the following readings are taken:
Engine speed (by counter).
Brake load.
Water temperatures, in and out.
Oil temperatures, in and out.
Oil pressure.
Pressure difference at inlet and outlet of water
pump (by mercury manometer).
Rate of water flow.
Barometer (one reading for test).
When the water pump capacity run is made for the
purpose of determining beat rejection to the cooling
water the temperature differences to and from the
engine should be measured at the time the pump­capacity
determination is made. The temperatures in
this case should be measured by resistance thermometer
units placed as close as possible to the engine inlet
and outlet pipes. In the installation of the resistance
thermometer units care should be taken to avoid stag­nant
pockets and to place the unit well in the water
stream. During such tests also, temperature readings
7
should not be made during adjustment of water
temperature.
The rate of water flow is determined by diverting
(by means of a three-way valve) the outlet water from
the engine for a given interval of time into a weighing
tank and weighing the water so diverted.
FREE WATER-PUMP TEST
The free water-pump test is made with the pump
connected to a small bench dynamometer. The pump
speed range is the same range covered by the test of
capacity of pumping through the engine. Cold water
is used for this te t and the capacity i measured by
weighing the discharge from the pump. At each 100
revolutions per minute increment of speed readings are
made of rate of water flow, pump speed, dynamometer
torque load, suction head at the pump, discharge head
at the pump, and water temperature. A determina­ti~
n is also made of the maximum pressure the pump
can exert (against throttle discharge) at the speed
corresponding to normal speed of the engine.
OIL PUMP CAP A CITY TESTS
Oil-pump capacity is measured by two methods­pumping
through the engine and pumping with free
inlet and outlet.
PUMP CAPACI'!'Y PUMPING THROUGH ENGi E
The oil-pump capacity pumping through the engine
is determined in a manner similar to the water-pump
capacity determination described on this page. The
engine is run at the dynamometer exactly as in the
"best setting" full-power run except that readings are
made of only engine speed, brake load, water tempera­tures,
oil temperatures, oil pressure, and rate of oil
flow. nless otherwise specified oil pump capacity
runs will be made with an inlet oil temperature of
120° F. The rate of oil flow is determined by measur­ing
with a stop watch the tin1e required to reduce the
oil tank scale indication by a given amount. For this
determination the oil discharged from the engine must
be directed to a separate tank. This method obviously
determines the capacity of only the pressure oil pump.
The capacity of the scavenging pump must be deter­mined
by free ·pump test.
In the oil pump capacity run, readings should be
made every 200 revolutions per minute from 400
revolutions per minute below to 200 revolutions per
minute above normal speed. A full set of readings
includes the following:
Engine speed.
Brake load.
Water temperatures, in and out.
Oil temperatures, in and out.
Oil pressure.
Rate of oil flow.
Oil pump suction head.
Oil pump discharge head.
Record should be made of complete physical prop­erties
of the oil used in this test.
FREE OIL PUMP TEST
The capacities of the oil pumps with free inlet and
outlet are determined in the accessories laboratory .
For this t est also the inlet oil temperature is main­tained
at 120° F. The pump is connected to a small
dynamometer and the capacity determined at speeds
corresponding to engine sp eeds covered in the full­power
run- 400 revolutions per minute below to 200
revolutions per minute above normal sp eed. Readings
are taken at 200 revolutions per minute increments
throughout that range. Separate tests are made of
the pressure and scavenging pumps.
The following readings are taken at each speed:
Pump speed.
Brake load.
Oil temperature at discharge.
Pump suction head .
Pump discharge head.
Pump capacity, determined by weighing the oil
discharged.
Oil specific gravity at test temperature.
Record should be made of complete physical prop­e
rties of the oil used in t his test.
A determination is also made of ihe maximum
suction head against which a dry pump will operate at
normal speed.
SPARK PLUG TESTS
Standard spark p lug tests are described in Air
Service Specification No. 28017- B, dated April 12, 1922.
THE 50-HO\TR ENDURANCE TEST
The 50-hour endurance test here described is con­ducted
to obtain comparative endurance information
on aviation engines. While it does not at all compare
in sever ity with t he endurance runs frequ ently applied
to meas ure Lbe durabil ity of aircraft engines, it is be­lieved
to be s ufficiently rigid to represent seveTal times
its duration in actual service and therefore a fair
measure of the serviceability of the engine.
Engine calibration.- Beforc undergoipg 50-hour en­durance
test every engine must be calibrated by the
electric dynamometer. The calibration should consist
of one full-power run (full rich and best mixture control
setting) and one friction horsepower run. Conditioned
carburetor intake air must be provided. The results
thus obtained should not fall any considerable amount
below the average performa nce for the engine under
test unless such a divergence can be accounted for in
special equipment or adjustment. During calibration
runs the engine should be carefully inspected for leaks
or other indications of improper assembly or adjust­ment.
If the calibrat ion results are satisfactory and
no unsatisfactory behavior develops, the engine may
be approved for the endurance test. If, however, the
performance or general behavior of the engine is unsat­isfactory
or defects develop, repairs must be made and
the dynamometer calibration rerun . Before removing
t he engine from the dynamometer the compression in
8
each cylinder should be tested by motoring the engine
slowly and listening for leaks.
Preliminary adjustments.-With the engine mounted
on the test stand the following preliminary adjustments
should be made :
(a) The engine should be thoroughly cleaned exter­nally
and spark plugs cleaned and reset if necessary .
(b) The propeller should be fitted to its hub and bal­anced
and tracked. The hub shmild then be installed
on the shaft following the procedure described by
Air Corps or manufacturer's instructions.
(c) The torque stand if used should be carefully
balanced so that it will remain in any position and so
adjusted that a weight of 10 pounds on either bearer
will tip it against the stop s.
(d) The torque scales, fuel and oil scales should be
carefully checked.
(e) The control installation should be thoroughly
inspected to be sure that the linkage allows them to
cover their fu IL range.
Starting.-Before starting the engine the lubrication
system should be filled with warm oil. The star t
should be made following as closely as possible the
manner of starting engines in service. Any starting
difficulties should be noted on the Jog sheet.
Warming up.-Previous to each run the engine should
be warmed up at less than 1,000 revolutions per minute
until the oil temperature has reached 100° F. The
warming-up period in no case should be less than 10
minutes.
Preliminary observation.- Before starting the first
test period the following observations and adjust­ments
should be made and recorded on the log sheet:
(a) Oil pressure.- The full-throttle and idling oil pres­s
ures should conform with Air Corps or manufac­turers'
specification.
(b) I dling.- CarbureLors should be adjusted so that
the c11gine idles uniformly at not over 400 revolutions
per minute. The lowest uniform idling speed should
be recorded on the Jog sheet.
(c) Ignition.- The synchronization of breakers and
condition of spark plugs should be checked by firing
the engine at full throttle on single switches and noting
the comparative speeds and the regularity of fu-ing.
The full-throttle engine speed on single swit.ches should
be not less than 98 per cent of the speed on all switches.
(d) Acceleration.- Note the smoothness of accelera­tion
with gradual and rapid throttle opening, and note
on the log sheet the nature of any irregularities and the
speed at which they occur.
(e) Fiill-throttle speed.- The fu ll-throttle speed of the
engine should not differ by more than 2 per cent
from t he specified endurance test speed. If full- t hrottle
t est s show a greater divergence, propeller modifications
should be made to compensate. Such tests should be
made on a fairly quiet day so that wind may not affect
the engine speed. The propeller must be rebalanced
after the adjustments have been made.
(f) Propeller hub.-After t he preliminar_y running
has been completed the propeller-hub bolts should be
inspected and tightened if necessary.
FIFTY-HOUR TEST
The 50-hour test is composed of ten 5-hour periods,
each period consisting of one-half hour at full throttle
and 47':! hours at 90 per cent power (97 per cent of
normal speed). The last hour of the last 5-hour
period, however, should be run at full throttle. At full
throttle the spark and mixture control should be set at
"best" position and left in that position for the re­mainder
of the period. Only the throttle should be
adjusted to reduce the load for the 47':! hours at 90 per
cent power.
The engine should be stopped during the 5-hour
period only in emergency, or if it becomes impossible
to maintain 97 per cent of normal speed. All stops
except emergency stops should be made by throttling
the engine and shutting off the fuel supply. The causes
of all stops except those at the completion of the
5-hour periods should be noted OJ) the log sheet.
A 5-hour period must be rerun if a stop occurs before
two hours of the period have been completed. Any
period requiring more than two forced stops must also
be rerun. The test should be discontinued if repetition
of more than three 5-hour periods is required.
At the end of each 5-hour period the following items
should be carefully checked:
Compression in each cylinder.
Propeller-hub nuts.
Propeller-flange bolts.
Manifold connections to cylinders and car-buretor.
Cylinder hold-down nuts.
Fuel, oil, and water fittings and lines.
Ignition connections.
Breaker points.
Distributors.
9
Once during each period a record must be made
of the fuel specific gravity.
During the 50-hour test notes should be made on the
log shee of all indications of unsatisfactory behavior of
the engine, including comments relative to vibration,
leakage, mLxture distribution, valve temperatures
speed variation, ignition, carburetion, etc.
PROCEDURE AFTER TEST
At the completion of the last 5-hour period the usual
inspection should be made and the engine returned to
the dynamometer for another calibration. The method
of calibration after test should be identical with that
before test.
THE CARBURETION RUN
The carburetion run is made to obtain complete per­formance
information on the carburetor engine combi­nation.
This test is applicable only to carburetors which
have been fully developed to a point where they are
thought suitable for use in service. The setting for the
carburetor must be obtained before the beginning of this
run and a record made of the flow of the carburetor
jets. For preliminary determinations of setting,
mixture-control orifices, etc., less formal tests will be
made.
All runs should be made with conditioned intake air,
except where specific instructions to the contrary are
i sued . The following readings hould be taken in
addition to the standard power and fuel consumption
readings:
Vacuum at throat of carburetor Venturi in
inches of water when possible.
Intake manifold vacuum, inches of mercury.
Carburetor float chamber vacuum, inches of
water.
At the end of each 10 hours of running the oil should Position of throttle lever on carburetor.
be completely drained from the system and fresh oil Position of mixture-control lever on carburetor.
put in. At such times the oil screens should be The position of the throttle lever will be read on a
examined for foreign matter by which engine failure graduated sector. It is preferable that this sector be
might be anticipated. attached to the carburetor itself so that direct readings
'1.'est readings.- Every 15 minutes during the 50-hour of the throttle movement arc obtained. However,
test the following readings should be taken: this is not essential, and where time and labor can be
Time, by stop watch. saved the readings may be made on a sector attached
Revolution counter reading. This reading to the control board. Sector reading for full: open,
should be taken at exactly 15-minute intervals and closed throttle should be recorded.
by stop watch. The position of the mixture control-valve will be
Torque load. read on a sector, preferably of metal, attached directly
Cooling water temperature, in and out. to the carburetor itself. The sector should be grad-
Cylinder head temperature, for tests of air- uated in degrees or have 10 equal angular graduations
cooled engines. covering the range of the control, and the readings
Oil temperatures, in and out. should be made from a pointer attached directly to the
Oil pressure. mixture-control valve in the carburetor.
Air temperature. The following group of runs will then be made (care
Fuel scales. These readings must be taken at being taken that there are no duplications of runs pre-exactly
15-minute intervals. viously made during the test on hand) . In many cases
Oil scales. These readings must be taken at where the carburetion run is a part of a general test,
exactly 15-minute intervals. (N OTE.- When some of the propeller load and full throttle runs will be
it becomes nece sary to add fuel or oil, the made prior to the carburetion nm, and these should not
exact weight added and the time of addition be duplicated.
should be recorded on the log sheet.) (a) Idling adjustment.- Adjust the idling so the
The barometric pressure should be recorded engine will fire uniformly on all cylinders at 300 revo-every
hour. I lutions per minute propeller load.
10
(b) Run lo locale "flat spots."-Run the engine at
every 100 revolutions per minute from idling to full
throttle on propeller load. Note all speeds at which
t he engin e operation is not satisfactory and describe
its behav ior at each of these speeds. Make minor
cha Dges, if possible, to correct these condit ions.
(c) Acceleration run.-Compare the acceleration
from idling with that of similar engine-carburetor com­binations
on t he type of test stand used , keeping the
operating condit ions as nearly identical as po~ s ible.
The accelerating qualit ies of the carburetor should
be noted with the cooling water both warm and cold
and record made on the log sheet.
(d) Full-power run.- Make two full -power runs,
taking readings at 100 revolutions per minute incr e­ments
from 400 revolutions per minute below normal
peed to 200 revolutions per minute abO\·e normal
speed. These runs will be made with the mixture
control in the " full rich " and "best setting " posit ions.
They a re better made together-that is, at each speed
take reading with the control in the full rich position,
then shift control to the best setting position and take
readings. The control should always be brought back
to the full rich posit ion when changing from one speed
to another. Great care sh ould be taken in adjusting
the mixture control, for if this is not done the maxi­mum
efficiency becomes a fun ction of chance rather
t han being a true indication of the carburetor-engine
efficiency. Different types of controls show different
characteristics, and the type on the carburetor tested
should be studied in advance. Some controls show a
definite Jag in their r esponse to the mixture control
adjustment, so that to obtain the best setting it may
be necessary to make a second adjustment, after con­ditions
have balanced, before readings are taken. (For
general instructions as to making full-power runs, see
p. 3.)
(e) Propeller load (standard).-(For general instruc­tions
as to making propeller-load runs, see p. 4.
These instructions are to be modified as indicated
below.)
Take a standard propeller load run with readings
at 200 revolutions per minute increments from normal
speed to 800 revolut ions per minute below normal
speed. The mixture control should be set at best
setting at normal speed and clamped there for the
remainder of the run.
(f) Propeller load (f1ill rich and best setting) .- Take
a propeller-load run at 200 r evolutions per minute
increments from normal speed to 800 revolut ions per
minute below normal speed , making all major speed
and load settings at full rich and best setting mixture
control positions.
Following is t he test procedure:
At full rich mixture control setting, no rmal speed,
a full set of tandard readings should be taken. Tlw
brake load recorded at t his condition will be the basis
for computing the brake loads for other speeds.
The mixture control will be adjusted to the best
settiDg, the speed a djusted to normal speed by manipu­lation
of the field resistance of the dynamometer, and
another full set of standard readings taken.
The mixture control must next be restored to full
rich position before the peed is reduced for the follow­ing
set of readings.
The engiDe output should be reduced by the throttle
to propeller-load operation (from full rich normal
speed) and the throttle clamped in position for all
readings at this reduced speed.
With the throttle still clamped, the mixture control
\\'i ll be adjusted to the best setting, and any varia­tions
in speed which occur due to power change will
be rectified by use of the dynamometer field resistance.
A full set of standard readings, including those listed
on pa ge 9, will be taken with this setting of the mixture
control.
This same procedure will be followed at the next
lower speed, etc. This will give two sets of readings
constituting data for t wo curves-
(1) A curve of hor epower and fu el consumption on
propeller load with the mixture control set full rich.
(2) A curve of hor epower and fuel consumption
with the same throttle openings at each speed as on
the fi rst curve, but with the mixture coDtrol adjusted
for the best fuel consumption consistent with main­t
enance of the desired power.
(g) M'ixture control run.- Bring engine to full
throttle normal speed with the mixture control in
the full r ich posit ion. Take a set of readings. Move
mixture control to second posit ion on quadrant, adjust
speed to normal with dynamometer resistance, and
take set of readings. Move mixture control to third
position and r epeat. Repeat this procedure, moving
mixture co ntrol one increment each t ime until either
the readings have been obtained for the total 10
increments of mixture-control movement or the engine
fun ctions so poorly as to ma ke readings impossible.
(h) M aximmn and minimum fuel heads.-(For in­stru
ctions for making this run , see below.)
THE CARBURETOR HEAD TEST
The object of t he carburetor head test is to deter­mine
the effect on brake horsepower and specific fuel
consumption of variations of fuel head at t he carburetor
and to discover t he minimum fuel head at which a
carburetor may safely be operated in an airplane.
Fuel should be supplied from a closed tank with air­line
connections for pressure Yariation. A vent valve
on the tank will make possible fine adjustments of
pressure. The rate of fuel co nsumption may be de­termined
by means of a special volume gauge co n­structed
for this purpose. For this run conditioned
air should be supplied to the carburetor .
1 nless it already has been defini tely determined, the
static flooding head will be det ermined on the bench
with several carburetors of t he type under test.
\Vith t he carburetor on the engine, the engine
running at full throttle, normal peed, mixture control
f ull rich, the fuel head will be lowered very slo\d y
from about 3 pounds per square inch until t he power
drops. At the lowest fuel head at which the engine
operates smoothly enough to permit readings, standard
power and fu el consumption readings should be taken.
The fuel pressure should then be raised to the point
11
at which definite power drop began and standard
readings taken. It is important that these points be
so placed that the nature of the power-fuel head curve
at thi end is clearly defined. If neces ary, several
closely grouped points should be selected for additional
·reading · to locate the curve of power drop. Power
and fuel co nsumption readings should be taken at three
equally spaced points between the point of power drop
and the static flooding point and also at the static
flooding point. The exact fu el head at the carburetor
inlet should be recorded for each condition. The
engine should be allowed to run long enough at each
point to insure uniform operation.
The minimum operating head will be considered that
point at which the fu el consumption begins to drop
rapidly indicating a metering in the fu el line rather
t han in the carburetor.
STANDARD CARBURETOR FLIGHT TEST
The object of the standard carburetor flight test is to
observe the operation of a carburetor under ser vice
condition·, partic ula rly with regard to the fo llowing
features:
(a) Altitude control.
(b) Acceleration.
(c) Action during ma neuver .
The test should be conducted as follows :
(a) The carburetor should be tested in an a irplane
with a fairly high ceiling. The mixture control lever
quadrant will be graduated in 10 divisions, numbered
from 1 to 10, starting from the full rich pos it ion of the
control. The only special instrument required for this
test will be a barograph.
(b) Warm up engine on ground and try acceleration
from lowest idling speed to full throttle, both with a
quick and slow t hrottle opening. Run engine for a
moment at every 100 re volutions per minute from
idling to full throttle, noting carefully the smoothness of
operation. The pilot's remark on accelerat ion and
general operat ion on the ground should be noted on the
Jog sheet.
(c) Climb to service ceiling, keeping mixture control
in t he Jeane t possible pos ition for maximum revolutions
per minute. Take readings of the position of the mix­ture
control lever on t he quadrant every 2,000 feet.
Note on log sheet pilot's observations on operation of
carburetor during climb.
(d) At e rvice ceiling fly level 1 at f u ll throttle and
take the following reading:
At best setting of mixture control- air speed,
engine revolu tions per minute, and position of
control lever.
At full-rich setting-air speed , engine revo­lutions
per minute, and position of control lever.
At full-l ean setting- air speed, engine revo­lutions
per minute, and position of control lever.
(e) Repeat the level flights required under (d)
15,000, 10,000, and 5,000 feet altitude.
' It is important that a constant angle of attack be maintained during
" level" flights, even if the altitude changes slightly. Fly by horizon
rather than by altimeter. ·
(f) At several altitudes, including about 15,000 feet,
10,000 feet, and 5,000 feet, make the following tests and
note pilot's observations on log sheet:
(1) Acceleration after a Jong glide with engine cold.
(2) Action of carburetor during service maneuvers,
especially steep angles of climbing, diving, and sidc­slipping.
INSTRUCTIONS FOR PREPARING LOG SHEETS
The following instructions have been prepared with
the purpose of making more valuable the original log
sheet test data both by making the records complete
and by establishing a uniformity of procedure which
will make such data intelligible to others. In the past
such test records have frequ ently been made with no
thought beyond immediate convenience, and there a re
consequently in the files numerous log sheets whi ch
a re meaningle s to anyone except the engin eer who
conducted the test-often unintelligible even to bim­simply
because the entries are badly confu sed or the
conditions of test a re not completely described.
Supply all t he information required on the sheet.
It is all necessary to properly identify the te t. Only
such information as obviously does not apply may be
omitted. For in tance, the throttle and mixture con­trol
limits (lower left corner) are needed only when the
throttle and mixture control positions are recorded in
the data by their posit ions on graduated sectors.
All miscellaneous information called for on the log
sheet must be filled in before the test is started. If
several runs are to be made in rapid succession without
interval for preparation of additional beets a sufficient
number of sheets should be prepared before the runs
a re started so that each run may be recorded on a
separate sheet.
Each test run shall be recorded on a separate log
sheet so that there may be no confu sion as to the
particular conditions of each run. A " run " consists
of a set of readings taken with a given test set-up and
under specific test conditions. If the set-up is changed
(new carburetors, spark plugs, fuel, etc.) or adjust­ments
made (such as carburetor setting changes) a new
run shall be co nsidered started and a new log sheet
used.
To identify the run the t itle, as it is to appear in the
final report, shall be written clearly in the space
marked " number and title of run ." The t itle should
be as complete as possible. For example, "propeller
load run" is meaningless. " Propeller load run,
standard equipment" or "propeller load run, ED- 52
carburetors " is more specific and clearly identifies the
run.
In the space for " Remarks" (lower right corner)
notation shall be made of special conditions making
the run nece sa ry, such as "Carburetor main jets
increased in attempt to get more power " or " Spark
plugs changed from Mosler M- 1 to B. G. 1- XB to
eliminate detonation." All special equipment also
should be listed in that space so as to positively
identify it. For example, " 7,500-foot supercharger"
is insufficieqt to definitely identify t he supercharger
12
equipment but "G. E. Form G 7,500-foot geared
supercharger" applies to only one particular design
and will not be confused with other superchargers
that may appear later.
All runs must be numbered and the log sheet must
bear the number of the run it records. Every test
log must be filed with the original data for the test
even though its data be worthless. If for any reason
the data on any sheet is erroneous the sheet should be
marked " Reject" and the reason for rejection given,
but it should in no case be destroyed.
Remember that the log sheet is not a personal record
but is to be filed as original data for the test and so
must be in such form that it will be intelligible to any­one.
Therefore, avoid uncommon abbreviations, sup­ply
all the information needed to completely identify
the test and apparatus, write legibly, see that the
engineer's and crew chiefs' names are recorded, and
mention all unusual circumstances likely to infiuence
the accuracy of the res ults.
FORMUL£ AND CALCULATIONS
In the formulrn and calculation on pages 12 and 13
the following symbols a re used:
A= piston area in square inches.
a=area of valve opening in square inches.
B = cylinder bore in inches.
b=barometric pressure in inches of mercury.
BHP= actual brake horsepower.
B.MEP= brake mean effective pressure in pounds
per square inch (corrected to sea level).
C=BMEP constant (BMEP= CX corrected
brake load).
D=total piston displacement in cubic inches.
d=clear diameter of valve port in inches.
E=mechanical efficiency in per cent.
FC=hourly fuel consumption, pounds per hour.
FHP= friction horsepower.
F1lfEP = friction mean effective pressure, pounds per
square inch.
h= maximum valve lift in inches.
HP= brake horsepower corrected to sea level.
JHP= indicated horsepower (FHP+ HP).
JMEP= indicated mean effective pressure - BMEP
+ FMEP in pounds per square inch.
K = brake constant for dynamometer.
5252 for 12-inch arm.
4000 for 15%'.-inch arm.
3000 for 21-inch arm.
1300 for 4 7'2-inch arm.
1000 for 63.025-inch arm.
L = length of stroke in inches.
Z= length of brakearm in inches.
N=engine speed-crank-shaft revolutions per
minute.
R= ear ratio Prop~ller speed
g Engme speed
S=fuel specific gravity.
W =brake load in pounds.
w=weight of fuel in pounds.
7r = 3.1416.
· O= angle of valve seat in degrees.
HORSEPOWEU
Dynamometer horsepower is computed from the
load, the brake circle circumference, and the engine
speed.
2.,,.z N W X N . .
BHP= W X rr x 33000=-r (for direct dnve)
where
K=12X 33000 198000
2.,,.z .,,.1
With a geared engine the dynamometer speed is
R times the engine speed, therefore
W X NXR . BHP K (for geared engrne)
Since the horsepower varies approximately as the
barometric pressure, the sea level horsepower can be
computed by the formula:
C t d BHP BHPX 29.92
orrec e = b
When correcting for variations in carburetor air
temperature it is assumed that the power varies in­versely
as the square root of absolute temperature.
The following formula, therefore, gives the brake horse­power
corrected to a standard temperature of 60° F.
(520° F. absolute):
/460 + T BHP (60° F.) = Observed BHP-y~
where T is the observed carburetor air temperature
in °F.
Friction horsepower computed from dynamometer
load is
FHP= Wii N (for direct drive engines)
W X N X R .
FHP= K (for geared engrnes)
JHP=Ji'HP+ HP
Mechanical efficiency is the ratio in per cent of power
delivered to power developed, or
E=HPX lOO HP X IOO
JHP HP+ FHP
The brake mean effective pressure may be determined
from the horsepower by the plan formula or from the
dynamometer brake load by means of the BMEP
constant.
or
HP=BMEP X L X A X N
12X 33000X 2
HP=BMEP X DX N
792000
SFC=specific fuel consumption- pounds per therefore
horsepower hour. BMEP HPX 792000
t=time in seconds for fuel reading. DXN
13
But since HP WXNX29·92 and since D is con­K
X b
stant for a given engine, t hen,
or
BMEP WX29.92X792000
K X bX D
BMEP-WC 29.92
- b
where
The friction mean effective pressure, FMEP, can be
determined similarly from the FHP or frict ion load.
No correction for barometric p ressure, however, is
applied.
The hourly fuel consumption by weight can be simply
determined by calculating the hourly flow from the
t ime of reading in seconds; thus-
FC=wX3600
t
When the fu el is measured by the volumetric appa­ratus
calibrated with fuel of 0.710 pecific gravity
the true w is obtained by multiplying t he ob en ·ed
weight w' by the correction factor O.~lO' thus
FC= 3600 w' X _§__
t 0.710
Specific fuel consumption is t he fuel consumption per
BHP per hour; therefore:
FC wX3600 wX3600 S
SFC=BHP=tX BHP t X BHP X 0.710
The area of valve opening is most accurately deter­mined
graphically and should be done so whenever
possible. If that method can not be used, however,
the a rea may be determined approximately by the
following formulre:
a=.,,. (dh cos o+h2 cos2 O sin 0)
For 45° valve seats
a=.,,. (0.707 dh+ 0.353 h2)
For 30° valve seats
a=.,,. (0.866 dh+ 0.375 h2)
INSTRUCTIONS FOR THE PREPARATION OF
REPORTS
Four general types of reports are written in t he
laboratory:
(a) Memorandum report.
(b) Project record.
(c) Standard serial report.
(d) Standard engine report.
(a) The memorandum report is a brief report written
in the form of a memorandum to the Chief of t he Power
Plant Section . It ordinarily covers the results of a
minor inve t igation, the outcome of which is not of
sufficient interest to warrant general publication, or of
a major investigation terminated prematurely by
failure of test apparatus or other cause and without
sufficient data to form a basis for a more complete report.
It is used also as a preliminary report on some pro­longed
investigation, the progress of which should be
reported to the chief of the section periodically.
The memorandum report is divided into numbered
paragraphs and treats the material of the report in the
following order:
(1) Object of test.
(2) Summary of results (briefly).
(3) General conclusions (briefly) .
(4) Introductory paragraph-a description of condi­tions
making the investigation desirable.
(5) Test material and apparatus- a description of
the devices tested or studied, together with any uncom­mon
apparatus employed.
(6) Method of test-general methods employed in
conducting the investigation.
(7) Description of test-history of investigation with
difficulties encountered, reasons for delays, changes of
equipment or methods, etc.
(8) General results and conclusions-general anal­ysis
of results and conclusions drawn therefrom.
(9) Recommendations-future procedure recom­mended
as result of this investigation .
(10) Data and illustrations.
In general, the above outline should be followed in
the preparation of memorandum reports. If the report
is very brief, however, it may be limited to several
paragraphs, stating the object of the test, general
results, and conclusions. The form must be flexible,
to be set largely by the judgment of the engineer and
decided, in ca e of doubt, by the chief of the laboratory.
Only such data should be included as are necessary to
clarify the text. Data in the form of curves should be
used as frequently as possible.
(b) The project record is the standard form of de­velopment
record in use at the Engineering Division.
It is written to cover extended developments and
should be used in connection with short investigations
only when such investigations are closely involved
'1 with some general development to which a project
number has been assigned. The form of the project
' record is that of a daily log. General instructions for
the maintenance of project records are given in Ad­ministrative
Circular o. 8. The following specific
instructions are added for the preparation of project
records in the power-plant laboratory:
(1) During the active period of a development the
project record must be kept up to date by adding
entries not less frequently than every three days.
When the development becomes sufficiently inactive
to make such frequent entries inadvisable, such a note
should be made at the entry terminating the active
period.
(2) If for any reason the development is tempo­r
a rily interrupted or permitted to lapse, the project
record should contain a note to that effect explaining
the reason for the interruption.
(3) At the end of each phase of the development
the project record should be su=arized by a general
discussion of the results of that phase. This summary
should be written as an explanation of the work to
14
date. The reason for the various run · should be
stated and the curves or tabulated data used to con­firm
the conclusions as stated. The engineer should
have the point of view of taking stock of what has
been accomplished so far in the test in order to determine
what is the next logical step.
(4) The project record is divided into four sections
indicated by the method of page numbering employed.
The text pages are numbered with plain numbers, the
data pages with D numbers (Dl, D2, D3, etc.), the
00 CK?m 'ELLt le L< AOC ffA2 /NP RCC. YTG VOR ~AL ' PC£t. ,PO• Vfi:' '> BRA ~E L ~AO. /J
~ I//
jl
·- I/ J
I I
I/ I/
l7n J '
~~ 7 I
<§>::
I
I
"',,.:l!
~~
~Ill r7 7
'Ill;
l~J.,.,, '/ I/
~ ~ I &"A EH< R~E PowEe
oj~ I
'-~~ v v / I v I
""' v I v v
/
IM ,,v
/v
v
IM
¥'f!RI !EN T io>F,. !leMA = .'£0
.<lo •lo "''
,_ 9 ln 1 !.o
FIG. 1.
curve pages with C numbers (Cl, C2, C3, etc.), and
the illustration pages with I numbers (Il, 12, 13, etc.).
(5) The project record is typed on " otear" paper
with three carbon copies on plain white paper. The
original and one copy are sent to the section chief, one
copy goes to the laboratory files and one is retained
by the engineer conducting the investigation. The
original copy shall be initialed by the engineer over
his typed signature.
(6) The data included in the project record should
be limited to curves and simple tables. The project
record is primarily a prompt repOTt of events rather
than a complete record of details, which should be
recorded on the original test log sheets. The writer
should bear in mind that the project record is written
for the information of others and hence should give
the reason for the work being done as well as the
results.
(7) Whenever possible, typographical corrections
should be made by pen to reduce retyping and to get
the record out promptly.
(8) The project record is not the last word in report­ing
projects, and the engineer's duties are not fulfilled
until serial reports are prepared summarizing the de­velopment,
either as a whole or in its separate phases.
The project record rarely gets beyond the section
chief, and all projects worthy of greater publicity,
therefore, must be written up in a serial report.
(c) The standard serial report is the form used to
report the results of completed projects or investiga­t
ions. It i prepared in form for blue printing, typed
on black-bordered vellum (Form 288) with curves
plotted on cross-section tracing cloth (Form 291) .
In general form the standard serial report resembles
the memorandum report, but its contents are more
complete. The following outline should be followed
in the preparation of the standard serial report:
(1) Title page.- Tit le of test, number of pages, date,
and signature of section chief and engineer conducting
test.
(2) I ndex.-Wlrnn contents exceeds 15 pages.
(3) Object of test.- One sentence stating briefly the
purpose of the investigation.
(4) Summary of results .- Table or brief statement
of results.
(5) Conclusions.-Brief statement of general con­clusions
and reco=endat ions.
(6) I ntroduction.-A discussion of the conditions
which have made the investigation desirable, with a
description of previous work in the same connection
and a more complete statement of the purposes of the
investigation.
(7) Description.-Complete description with refer­ence
to illustrations of material tested and of any
uncommon apparatus used for the test.
(8) Method of test.-Outline of general method of
test procedure, including runs made, fuel used, oil
used, and detailed description of any test procedure
not described in laboratory instructions.
(9) Record of test.-A story of the test with diffi­culties
encountered, remedies employed, sources of
possib le error, and general discussion of results with
reference to curves and data pages.
(10) Conclusions.- Complete statement of conclu­sions
based on results described in the previous
paragraph.
(11) Recommendations.-Wlrnn the paragraphs on
conclusions do not make the recommendations obvious,
suggest here further investigations desirable or imme­diate
action warranted by the results of this in­vestigation.
(12) Bibliography.-List of Engineering Division
reports and other references bearing on the subject.
(13) Illustrations.-For convenience in assembling
and handling, the illustrations are placed near the
end of the report.
(14) Curves and data pages.-These pages should
include all data useful in clarifying t he text. Make
data graphic whenever possible to simplify reference.
d. The standard engine report covers the results of
the standard engine test. It is completely described
in " Instructions for Conducting Standard Engine
Tests and Preparing Standard Engine Reports,"
Engineering Division Report, Serial No. 1506.
0
f
I
Mat. Div. A. C. 736-Wright Field 7 -25 -27-800
WAR DEPARTMENT
MATERIEL DIVISION, AIR CORPS
WRIGHT FIELD, DAYTON, OHIO
Dyno. No. ___ ___________________ __ ___ _______ ___ _ Date ____________________________________________ __ ____ __ ________ _
Report on Calibration of Dynamometer Scales
Before t est of ___________________________________________________________ ____ ____ _
Engine f C?nnected L Disconnected
Check Wt.
SCALE SIDE READING OUTSIDE READING
on 63" Arm. Up Down Avg. Error Up I Down Avg. Error
'
I
I
0
50 I
100 I
150 I
I
200
GASOLINE SCALES OIL SCALES
Check Up Down Avg. I Error Check Up Down Avg. Error
Weight W eight
I
Repairs made --------------------····------------------------------ -- ----------- -·---------------------------------------------------------------------------- -------- -- ------
Reported by ________________________________________________________ __ ______
E. 0. No. ___ __ ____________ _____________________ Project No. P------------------ ---- --·
Date ------------------------ ------- ---- ------ -- -- -- ---- --------------------------------------------·
No. and Nature of Run·--- ---- -- ------- -------------------------,--------- ---------- ---·
Special Conditions -----------------------------------------------------------------------·
~:::ui:o::!~r } No. _____ ___________________ Brake Arm Length ___ ____________________________ Jn.
Oil Used ___________ __ _____________ Viscosity ______________ __________________ Sec. (Saybolt) at 210 F.
Fuel Used ____________________________________ Spec. Grav. ___ __ __ ___ ____________________ at _____ ____________ o F.
Spark Plugs ------------------------------- ----------------------- --------- ------ ---- ----------------------------------,--
Barometer Before _____________ __ _____ ____ __ _____ ______ __ After ______ _______ ______ Avg. _____ __ ___________ __ _
Mixture Control Position ____________________ ___ Full Rich _______ ______________ ___________ Full Lean
Throttle Position ___________________________________ Closed _______________________________ ___ ____________ Open
Mat. Div. A. C. 737-Wright Field 7-25-27-800
Page No. ______ _________________ ____ _
WAR DEPARTMENT
MATERIEL DIVISION, AIR CORPS
POWER PLANT LABORATORY
Ma e of Engine ____________________ ___ __________________________ ModeL ________________________________ __________ _
A. C. No. _________________ __ __________________ _____ _____ _______________ Mfr's No. _____________________________________ _
Piston Displacement Cu. In. TotaL ____________________________ Per Cyl. _______________________ __ ____ _
Cojpression Ratio ----- ---- -- ------------------------------------------------------------------------- --- -----------
I WRIGHT FIELD, DAYTON, OHIO B. r· E. P. ConstanL ____________________________ _____ With __________________ Jn. Arm.___________ _______ I
I
l
..
CARBURETOR SETTINGS:
Carburetor Used -- ----- -- -----------------------------------·------------------------------------ --- ----------------------------------­Venturi
Size -------------------------------- ---------------------------------------------- --- ---------- ------------- -- ---------------- -----
Main Metering Jet _____ ______________ ___ ______ _____ Flow _____ _________________ Br. Pt./ Hr. B. & B. Flowmeter·
Comp. Metering Jet ____ ______ _____________________ Flow _____ ________ ____ _____ Br. Pt./ Hr. B. & B. Flowmeter
Air Bleed Size·---- ---------------------------- ------ ------ -- ---·------------------ --- --------,-- -- ---- -- ---------- -- ---------------------­Special
Conditions --·---- -- --------------- -------------------·- --- ------------ ----------- ----------------------------------------.-------
~ I
I
!
I
i
Remarks: ---------------- -- ------------------------------------------ --- --- -------------------·
·-----·------------------------------ -----------------.- -------------.- ------------------- -- ------ ---------·
Engineer ----------------------------- -- -------------- -- --------- ---'---------------­Crew
Chief ------ -- --------------------------- -- -- ---------------------------------
I
I
I
I
I
i
I
Date ___________________________________ E. 0 . No. __ : ___ ______ __ __ Project No. P-_____________ ___ Part No. _ _______ ___ Page No.·--· -- --· -- . ENGINE TEST LOG SHEET Make of Engine______________________ __ Model. ______ ____________________________________________ _
Project Title ------------------------------- -------------------·-------------·--------------------------------------------------------------------------------------:
No. and Title of Run _ ___ _____ _________ ________ ___ _________ ___ -- ----· __ ·------------- ---- ------------------ --- --------------------- -- --- -- ---------------------
MATERIEL DIVISION, AIR CORPS,
ENGINEERING DIVISION, AIR SERVICE,
McCOOK FIELD, DAYTON, OHIO.
A. S. No. ______________ __ ____________ __ ___________________ Mfr's No .. ________________________________________________ _
Piston Displacement, Cu. !n .. ______ _. ____ ---·----------------,------ ---------------------------------------- -.
Compression Ratio -------------------------------------------------------------------------------------------~---·
This Is the complete test record. Make it intelligible to others. Be
sure that a ll required da·ta are recorded. Use separate B. M. ·---- ------------- -------- -------------------------------------------- --- -- --· ----------·-- ---------- ------------------- -------- ------- --------- ----------- ------- ----·-----·-·· E. P. Constapt ... ------------------- -------------------------------------------------------------------------- sheet for each run.
TIME
Tach.
R.P. M.
COUNTER
READING
Before After
BRAKE
LOAD
Pounds
Be fore After
WATER
TEMP. oF.
In Out
OIL
TEMP. OF.
OIL
Press Scale
Lb./ Rdg.
In Out Sq. -In. Lb.
FUEL
Carb. Man. I Throt- Mixt.
Air Vac. tie Cont.
POUNDS
Temp. In. Posi .. Posi-
Before After
Time OF. Hg. ti on tion
By Vol. Cor-
Sec.
rected
Factor
I
----~-++-~~--t-t--~~-t-~·~-+~~~ ,'
'
•
~:;qau1:0s~!~r J No. _ __ ___ ____ ____ __ _______ Brake Arm Length _____ __________________________ Jn.
CARBURETOR SETTINGS:
Oil Specification No. _____________________________ . _ ___ ______________ _____ _________________ __________ ____ . __ ____ _
Carburetor Used ------------------------------- -- -------------------- ----·----
Fuel Used ____________ ____ __ _______ ________ ___ ___________ Spec. Grav ._ _______ _______ _____ ____ at ___________ ° F.
Venturi Size ----------------------------------- ----- -- ------------------·---------
Spark Plugs ----------------------------------------------------- -------------··· .----------------------------------- --· Main Metering Jet ----------------------------------------------------------
Barometer, In. of Mercury ___ ____ ____________ _______ ____ __ __ _________ ______________ __ __ ______________ ________ . Comp. Metering Jet _ ------------------------------------------------ ___ .
Mixture Control Position _________________ ________ Full Rich _____ __ ___ ____ _____ _____ .... Full Lean Air Bleed Size ________________________________________________________ .. ______ _
Throttle Position --------------------- -------~---------Closed ____ _______ __ ~----------------------------Open Special Conditions
Mat. Div. A. C. 737 A-McCook Field 1210-26-2M
ACTUAL
R.P.M.
Brake
Load B.H.P.
Pounds
I
'
I
I
I
CORRECTED
B .M.E.P.
B. H.P. Lb./
Sq. In.
FUEL CONS.
LB./
B.H.P./Hr.
Lb./Hr. (Act ual
B. H.P.)
OIL CONS.
Lb./Hr.
Lb./
B.H.P./ Hr.
(Cor­rected
B. H.P.)
Re~ar~s: :: ::: : :: : :: ::: :::::::: : ::::: :< :: :l ::: :::::: :: :: ::::: ::::: :::: : :: : : :: :: :: :::::: ::::::: : ::::::::: :::: : ::
------- --------------------- ------------------- ----- ------------- ----------------- -- -- --------.. ---------------------------------------------------------------------------------------------------------
----- -------- --- -- ---- --- ------------ ---- ---- --- -- ------ --·----- --·--------------- ----- ------------------ ---------------- ----------------- ------ ----·----------------- ----------------------------·--- --- -
--------------- ------------------------------------------------------- ------------- --------------------------------------------------------- ---------------------------------------------------· .. ·-------
----- -- ------- ------- ---------------------------- -------- -------- ------ ----- --------------- ---------------------------------------- ··-- ----- -- ----------- ------ ---------------------------------------- ---
---- -- --- ------------------------- --------------- ------------- ·-· ----·- ---- ------ ---- -- -------------------------------------------- --- --- -------------- --- ----------------- ---- --------------------------
Engineer ______________ . _ .. ________ . ___ ... _. ____ __ ... _________________________ _______ __ ____ __ _____ ,_. ______ . ______ ____ _____ _____________ _. ___________________________ ... _
Crew . Chief _____________ ....... ____ .... ____________________ _____ ____ __________ : ______ ____ __ _______ . __________ __________ : ______ --------------------------------- ·---- --· _
E. 0. No .... ·---------------------------------------------------·------·
PRELIMINARY INSPECTION.
WAR DEPARTMENT
MATERIEL DIV N, AIR CORPS
POWER PLANT LABORATORY
WRIGHT FIELD, DAYTON, OHIO.
ENGINE AND MODEL.-----------·----·--·---------------">-J.---·-·-··-------···
A. C· No.·--------------·-------------------·----MFR'S NO·------------···-----····-···
TESTED ON ·----·---------·------------------------------··----------·-··-·---···-·--··
--(Torque Stand or Dynamometer)
ROUTINE ENGINE TEST
(a) Cylinder Compressions when tried by hand (0. K. or note weak cylinders) ---------·-··-··················--·--··--·-·-·······-·-··----------------·-···--·-·--· ---------···--------- ------··-····
(b) Carburetor Flooding, Engine not Running?···--------·--··-·-·--·-·····-·-··········--·-------·--·-····-·--········-···········-·-···-··-·-··-········---------·-····-···---------·-·-··------------------------·-····
( c) Water or Oil Leaks?-----------·----·---- -- -·-----·-····-···--·----------·-···-·------------·---·······-···-·········-······-·····················--------------------------·------------------·----------··-----·········--···----·
( d) Carburetors Used, Name and Type---·---·-·--··--------- ----------···-------··----·-············-···-·----------·-·····-··············-·--···-···--·-··-·····----··-···---------------·-···--··-----------------····-··--
Venturi Size .... ·-·-····-·-· ----·---------------Main Jet Size ______________________ Flow ······--·----------------···---------·-·····Comp. Jet Size _____ _______________________ _____ Flow ----···------------·
RUNNING IN. DATE BAROMETER
I Tach. I
Load Water Temp. °F Oil Temp. OF
I Oil I Af I I Tach. I
Load Water Temp. °F Oil Temp. OF
I Oil I
Afr
Time Press Te.:p. Time Press Temp.
R.P.M. Lb. In I Out In Out Lb./Sq. In. OF R. P.M. Lb. In Out In Out Lb./Sq. In. OF
I I I I I !I I I I I
I I I I I II I I I I
I I I I I II I I I I
I I I I I II I I I I
I I I I I II I I I I
I I I I I II I I I I
I I I I I II I I I I
I I I I I II I I I I
I I I I I II I I I I
I I
IDLING RUN (Engine must run not over 350 R.P. M., full advanced spark) .
Time Counter
IR. P. M.1
TEMPERATURES°F
I Oil
Fuel Cylinders Plugs Does Engine hit on all cylinders when opened wide after this run 1
WATER I OIL Press Scales
Min . Reading In [ Out In I Out AIR. Lb./Sq. In. Lb. Missing Fouled
0 I I I I I I I
5 I I I I I I I Plugs changed or deaned after this run?
10 I I I I I I I
15 I I I
PRELIMINARY RUNS.
(a) Oil Pressure at Full T hrottle ______________________________ ___________________ __ ____________ Oil Pressure at Idling __________ ___ __ ________________ __ ___________________________________________ __ ______________ _
(b) Acceleration from Lowest Idling Speed with Spark Advanced (Good or P oor) . Quick Opening __ __ __ _________________________ Gradual Opening _______________ _____ __ _
( c) Does Carburetor give Smooth Operation at all Speeds?-----------------------------------·-----···············--·--------------··-----·---------------------------------- ---·--·----------------------------------
At what Speeds do ''Rough" Spots Occur, If Any?--------------- ----------------·------------------------·-------·------------------·------,--------------·------------:-----------------------------·---- -----·-·­(
d) ' Synchronization of Ignition Breakers: R. P . M. Both Switches---·-----·--···-----------------------···---------------------------·------------····----------------····-··-----·-----------·--·-··------------
FULL THROTTLE FIVE-MINUTE RUNS.
R. P. M. Right Switch_·-··-------···-----------·----------·--···------------------------------------ ----·-------------··-----·--·--------------------··-------------­R.
P. M. Left Switch ... ----------------··------------------·------ --------------··-------------- ·-------------·-··--···-···-···--·------·------ ------·--·-·------- --
DATE BAROMETER
TEMPERATURES OF I Oil I Man. j FUEL, LB. II I Load I B.H.P. 1~EL CONS.
Water I Oil I Press. Vac. R p M uncor- / Lb/
In I Out In I Out AIR lbi~~q. ~:.. Before I After . • . Lb. rected Lb/Hr. __T_ IM,...E_ _ sir..:
1
__ ca°_E~~~-1~-~-1 LOAD, LB. I
Start Stop Before I After Before I After
NATURE OF RUN
Normal Speed, Full Rich
Normal Speed, Best Setting
200 R.P.M. more, Best Setting
200 R.P.M. less, Best Sett;ng--
.I II
II
II
II
R. P. M. Full Throttle, Full Lean·-------------------------·····----------------·-----·----·-----------------Brake Load -----·-·-···-··--···-···-·········-··-·······--·--···-··---·--------------------------------------------------
ONE HOUR RUN AT 90% NORMAL SPEED PROPELLER LOAD, MIXTURE CONTROL BEST POSITION.
I Time
TEMPERATURES °F
I
Oil
I II
/ Counter I I FUEL CONS. I OIL CONS.
I Load I WATER I OIL I Press. I Man. I Vac. SFcuaelels ScOaliel s R.P.M. B.H.P. Date I Lb/BHP. I Lb/BHP.
Min. Reading Lb. In \ Out In \ Out AIR Lb/Sq. In. Hg. Lb. Lb/Hr. Hr. Lb/Hr. Hr.
I In. Bar. In. Hg.
0 I I I I I I I I I I I II I I I I I Fuel Used
15 I I I I I I I I I I I II I I I I I
30 I I I I I I I I I I I II I I I I I Oil Used
45 I I I I I I I I I I I · II I I I I I
60 I I I I I I I I I I I II I I I I I Plugs Fouled
Avg. I I I I I t I I I I I II I I I I I
Were any cylinders over-oiling during above run? Where.---------------·-·-----------------·············--------------------------------------------·------···--------·-···--·------------·--- ------------·--------------------
Time at End of One Hour Run ____________________________ _________ ______________ Time of Stop--------··········-------------------·---······- (10 Min. to be consumed in slowing down and stopping).
COMPRESSION PRESSURES, VALVE TIMING AND TAPPET CLEARANCES. (COLD ENGINE)
CYLINDER
PRESSURE
INT. OPENS
INT. CLOSES
INT. TAP. CL.·
EX. OPENS
Jl:X. CLOSES
EX. TAP. CL.
BREAKER TIMING AND GAPS.
BREAKER N 0 . I I I
Degrees Advance I I
Degrees Retard I I
GAP I I I
RUN Control Pos. j
Full throttle, Normal Speed Full Rich I
Full throttle, Normal Speed Best I
Full throttle, 200 r.p.m. less Best I
Full throttle, 200 r.p.m. more Best I
One hour run . Best i
I
I
R.P.M.
Carburetor Strainers Cleaned ? ··-···-·········-----···--·······-··--·----------···········----·-··-----------­Oil
Strainers Cleaned? ------------··-···-------------------------------- ------------------·-- ---------------------·­Condition
of Engine Equipment 0 . K.? ---·-··---------------------- -----------··-·---------···----·------­Prepared
for temporary storage?··-·····-·-·········--------------------·-----·-····-·----------·------------·
Exhaust Ports and Air Intakes covered?--······----··-------··-·····---·-········--·-----·-····---------- --
SUMMARY OF TEST RESULTS
\ .s. H. P. i FUEL CONS. I OIL CONS. II REMARKS: ( 0 . K. or in what respect not up to specified
Lb/Hr. /Lb/BHP Hr. Lb./Hr. performance) ,
I I I I II
I I I I II
I I I I II
I I I I II
I I I I II
Repairs or Replacements ········--·-·-·-····························-·-······-···-·--- ------···-···------------······--·-··········-······-···········----------- -----···-··-·-·---·-···-·-······-·······-···---·-·------------··----·-····-----------
Mat. mv. A. C. 66°Wright Field 7-25-27-800
Tested By: ··-·-·······-····-··----·····--··-----·--·-····-···---------·---Date _____________________________ ___ ____._ _
Checked By: ----------------·······--·-···-···-···············-·----····----Date ___________________________________ ..
Accepted or Rejected ........ ·-····--------·-·······-······------·-------------------------------.----···-·-----------
I f Rejected, Why?·-·-·······-·····---·----·--··-···········-···-·---------------------------------------------------­Approved
-----·---- ---·-------··-·--·-------------·-···--····--------·····-··-------·-·--·-·-·-·-··-····-···-Engineer
Mat. Di v. A. C. 67 -Wrig nt J:· ic w ,.z6-2 7- 800
Run
Nature of Run ................................. .. .... .
Orifice Throttle Nominal
R. P.M.
Size Opening
of
Altitude
IOOO's
In H20.
HEAD
ORIFICE
Choke Box
WAR ·PARTMENT
MATERIEL DIVISION, AIR CORPS
CARBURETOR TEST
POWER PLANT LABORATORY
WRIGHT FIELD,, DAYTON, OHIO
VACUUMS
Air . Secs. Mix.
Ma nifold
Floa t In. Temp. I Lb. Cont.
Ins . Deg. Eng ine F eet
Chamber
• F. Fuel Pos.
1~------- In. Hg. In. H g. 1~------- 1
In. H20.
E. 0. No ........................... :: ..................... .
Date ........................................... ............ .
Abs. Orifice Orifice 1Bar. Air Mix.
Ratio
Temp. He ad Coe f. Corr. Flow
Lb. Air
• F . In. HoO. Factor Lb.-'Sec. Lb. Fuel
Reading j Corr. F ront Rear
-~~'--~~~--~-+~--~~.:;:.;~~.,;.._.::;::.;.:..:.._~ ~~-r-~~--1~~~-t-~~~-~~~-~-1-~~-+~~~~~--1-~--t-~~~f-- ~-+~~~+-~~-+-~~-+~~~+-~~-+-~~~
ZERO RE ADING
I
-~~t--~-t-~~-1-~~~+-~~-'-----1--------1-----+-----+---- - ~- r- --l----i---1- -
-
i
I
I
- 1~---t---·~-+---+----+----t-----t---
I
I -
----~ · ~ I
I
-!--·..--- -
I
I
I
- -
Carburetor Used ............................................................ .. Baromet er : .. ............................ Test made by ........................................................................................ .
Chokes ................................................. . Remarks : ----------------------- --- ---- ------------------------------------------------ ----------------------- --------------- ---------------------------
Maint Jets ........................................... .
Comp. Jets .......................................... ..
I.