Technical bulletin no. 45. Development of military aircraft material for United States Army Air Service under supervision of Engineering Division

              CONFJDENTr~L
Auburn University LibrariPs
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3 1106 025 85039 '2
AIR
VOLUME V
. );
(AVIATION AND AEROSTATION)
BY DIRECTION OF CHIEF OF AIR SERVICE
FOURTH QUARTER - 1925
TECHNICAL BULLETIN
No. 45
NUMBER 487
DEVELOPMENT OF MILITARY AIRCRAFT MATERIAL FOR UNITED STATES
ARMY AIR SERVICE UNDER SUPERVISION OF ENGINEERING DIVISIOK.
Prepared and Published
By Direction of the Chief of Air Service
and under the supervision of
JOHN F. CURRY, Major, A. S.,
Chief of Engineering Division.
McCook Field 1-11-26-lM
CONFIDENTIAL
The information contained herein is confidential and therefore
must not be republished, either as a whole or in part, without
express permission of the Chief of Air Service, U. S. Army.
CONTENTS
AIRCRAFT DEVELOPMENT
AIRPLANES
Douglas Observation Airplanes ------ ---- -------------------- _____ ---- ----------- ------------------ -- 7
Huff-Daland Light Bomber Placed in Production -----------·------------ -- ------------------ ·-- ·- -- 10
Boeing Pursuit Airplanes (Production Article) ___________ .... .. -------- ·- ______________ .. ___ ___ __ ___ 10
X0-6 All-Metal Airplane Passes Static Tests ·· ··-- .......... ........ _ ... -----····--------------- 11
Bids Rece'ived for Heavy Bombardment Airplane (Monoplane Type) ----------------·--- 12
Shock Absorbers ---- -- ---------------- -- ------ ---------- ··---------- ----·--· ---- -- -- ---- ----·----·-·------------ - 12
Design Study for Night Observation Airplane_·- --- --------- ------------·· ----- 12
AIRSHIPS AND BALLOONS
New Airship for Primary Training , Model TF-L ____ ____ ----------·-··-·---- ·--------------- 13
Aii-Metal Car for TC Airship -------- -- ---- --- ---- -·· ·-----·--- ----- --------·--·---- ·-··----- __ ---·--------------·-- 13
Improved Helium Inflati'on Equipment ------·----------- -----·--·- --- --------------- --------- ----· ···-------------- 13
Helium Purification Railway Unit __ ------ -------------- ------·- --- ------------------- ----------------·------------- 14
Erection of Mooring Tower at Scott Fi'eld Delayed_ ·---- ----------- ·--··----- ---- -- --- --- --···--·----·- 15
Redesign of Bar rage Balloon --···------- _ ·-------··-----·· ------- ----·--------· ·--·-- ------ ------ ----- ----·-----·-· 15
ARMAMENT
Investigation of 0-2 and LB-1 Airplanes for Ground Attack... .... -- -----------·· ·······--·-· 15
New Bomb Rack for Production LB-1 Airplanes _______ ---- ---------------- ---- -------·-------·------------- --- 15
EQUIPMENT
:t',,"ight Flashli ght Photography ________ ----- --- -- ------· ····----- ______________ ---------- ---- -- --- ------- ·-- __ 17
Kryptocyanine Film -- ------ ---·---------------- --- ------- ------------·--- __ ____ ______ ,,__________ ___ _____ ___ __ _________ 17
Transmission of Ae1'ial Photographs by Radio Proposed --·--·---·-- ----·--·------------· 18
Pyle-0-Lite F loodlight ---- --------------------------·-·----··--··--·----------------·--·····--·------------- -- -·--·-··-----·----- 18
Short Type Airplane Landing Light . ______ .. ____ ____________ ___ __ ___ ________________ __ --- --- -- --------------·- ----- 18
Changes Proposed to Increase Life of Aircraft Storage Batteries___ ___ _____ __________________ __ ____ 18
Inertia Starters _________ ------·· ······---------- - ------ -- ---------- ·--···------- ·------··· ···----------- ---- -- --- --··----··--- ------ -- 19
New Instruments ___ __ . _ __ . ___________________ ___. . __. .. _. __ __________ _______ _____ -·· _________ .. _. ____. . ____ . _____ .. ·-· __ __ . 19
SCR-133 Radio Set Control Box Made Smaller ------ ----- -- --------------------- -------- --------·· _____ ____ __ 19
P ortable Filling Device for Cross-Country Airplanes -----·-------- -- ----- -- --- --------------------- --- -- 19
POWER PLANTS
Progress on 1200-H. P. "X" Type Engine ___ ··· ··--- ·-·---------- ------------------- -- --- --------------· 19
Development of Curtiss R-1454 Radial Engine _______ __ ----- -------- -- ------ ------- --------------------- 2J
Air-Cooled Liberty Engines ------ ----- --- --- ----- --·----·------ ---- -- -- -·----·--·---···---------·--· ---····--·---·---- -- --- -- . 21
Kingsbury Thrust Bearing -------- ---------- ---- ------------· --- ------ ---- ---·-----· ··-·-·-- --------- -------··-·-------- 21
Investigation of Carburetor Metering Jets ··----------- ___ ____________________ ----- -- --- -- -- ------------- ---- 21
New Stromberg NA-Y5D Carbm1etor for Curtiss D-12 Engine__ __ ____ _____ _________________ __ 22
Scintilla Double Type Magneto _____ ___ _ -------- .... _____ -- ---··--·· ····· ·-- -- ---·······--·--- --- 24
Breaker lVIecha ni s1ns ------ ---··-·-------· ---- --- -- -·---·---· ·· ·----· ·---·-- ---- ---- ---·-·--·--- ------ --· - ----------·-··-·----- 24
Splitdorf Model VA Magneto .. ... ______ ------ ------·--· -- ---------- --- ·--- ----------·----- -------- -------------------- -- 24
B. G. Midget Spark Plugs -·---·---------------- ·----- -- ----·----·- ---·- --- ---- ----------------- -- -- --· -- ------------ ------------- 25
C 0 NT ENT S - (Cont'd)
RESEARCH AND EXPERIMENT.
RESlTME' OF ENGINEERING DIVISION SERIAL REPORTS.
Charts for Solution of Stresses in Airplane Wing Spars____ ____ ________ __ ____ _______ __ _______ 26
Airplane Performance as Dete1,mined by Modern Con ception of Drag __________ ___ . 26
Static Test of Curtiss P-1 Wing s ___ _____ ____ ____ _____ ___ _____ _____ --- ------ ---- ----- ---- ------- --- ----- ------- 27
Static Test of Woven Plywood Wing (Forest Products Laboratory) ____ ____ __ ---- ---- ---- ---- ---- - 27
Wind Tunnel Tests -- --- ---- --- - --- ---- ---- ------ -- --- -- -- --- ------- ---- -- -- -------- -- ---- ---- --- ---- -- -- -- ------ -·- ------- -- ---- 27
Recommendations for Improving. Flig ht Indicator ----- --· ----- --- ----- ----- ------- --- -- --- ------ --- _______ __ 27
Three-Leg Speed Course ---- ---------- --- ------ --- ---- --- -------- -- ------- --- ---------- --- ----- ·--- -- --- ---- __ ______ ___ ______ 28
Location of Airspeed Tubes on TC Airships _ --- ------- --------- --- --------- ----- ----· - ------- -·-- ------· -- ------- -- 28
Pe1,formance Tests ------- -- ----- -- -- ---- --- ----- ---- ------ ---- ----- --- ---- --- -- -- --- ------ --- ----- ----- - ---------- --------------- --- 28
Cadmium Plating by Means of the Udylite Process -- ---- -- ------ ------- -- --- ---- ---- ------- ----- - 28
Second Test of Liberty Engine With Experimental Parts_ ___ _______ ---- ------- -------- -- 29
Bearing Load Analysis of the Air-Cooled Liberty Engine ... ____ _____ ------· ----- -- -· 29
Test of Stromberg NA-S12 Carburetor for Packard lA-2500 Engine 30
Valve and Induction Losses of Typical Aircraft Engine Cylinders____ __ ___ ___ _________ ___ ____ __ 31
Standard and Katalite-Coated Liberty Cylinders__ ___ ____ ___ _____ ___ ______ ____ ______ _______ __________ _______ 32
First 50-Hour Test of Air-Cooled Liberty Engine___ _____ _____ _____ ____ _____ ___ ____ __ ___ __ ___ _____ 34
Endurance Test of Packard lA-1500 Eng ine ------ --- ------ --- ---------- -- ------------------- --- ------ 34
Tel't of Viking Type Fuel Pump (Wright Aero. Corporation)_ __ __ __ _______ ____ ______ __ __ ______ __ ________ 34
Test of Zenith ED-52 Carbuvetors on Curtiss D-12 Engine______ ____ ___ ___ ____ __ ________ ____ ______ ___ _____ 34
Bearing Load Analysis of High Speed Curtiss D-12 Engine ______ ___ __ --- ------ ---- ---- ---- --- ------- -- 35
Development and T est of Stromberg N A-Y5D Carburetor for Curtiss D-12 Engine 35
Test of Stromberg NA-U6A Carburetors on Wright "H" Engine ____ ______ __ -- ---- --- ----- ---- -- -- 35
Cylinder and Manifold Pressures During Induction and Exhaust Strokes______ _________ ____ 36
Development and Test of Zenith ED-52 Carburetor for Liberty Engine__ ________ __ _______ __ __ 36
Third Endurance Test of Liberty Engine With Experimental Parts________ 38
INYESTIGATI01' OF MATERIALS
Effect of Aging on Elasticity of Aluminum Alloys ____ __ _
Hardness of Piston Alloys at Elevated Temperatures ___ __________ ____ ______ _
Correlation of Rockwell, Scleroscope and Brinell Hardness ______ _____ __ _
NEW BOOKS AND DOCUMENTS
39
39
39
Additions to Engineering Division Technical Files during Fourth Quarter, Hl~ f>_ _ 40
Additions to Engineering Division Technical Library during 1925____ _______ 46
LIST OF ILLUSTRATIONS
Douglas Observation 0-2B (Night Flying Article with Dual Control )._________________ __________ 6
Douglas Observation 0-7 with Packard lA-1500 Engine·-· --·-------------·--- -·-· -·- ---·--------- ----·--·- 7
Pilot's Cockpit in Douglas 0-2B -------- -·---·---- --· -- ··-·- -·· ·-·· ···--·-- -·-·---·- ·-·- ·--······-··--- ----------- -·· -- 8
Observer's Cockpit in Douglas 0-2B showing Dual Control Installation__________________ ____ 9
Boeing Pursuit PW-9 (Production Article) -· -· ---· ·-- ------- ·--· ·---····-- ---- ··- -----·- --- --·-··· -·------- ·-· -··· 11
Helium Inflation Man"ifold, Type B-1 -·-··-·····--·-----·-------·- ··- -- -- -------------·-· ··-----·--··----··--------· --·-· 13
Helium Inflation Tube Connector, Type A-1 -----·----- ···-- -· ·---· -··-·----- -------- --···--· ·-------- -·---- ·---·-· 14
Bomb Rack D-2 in XLB-1 Airplane showing Bomb Hoist C-2 in Position for Rais-ing
Bombs to Internal Rack Positions -·-· --· -·----- ---·---· -- --- -- -· -·---··-· ·· ·····--·-- ·--- ---- -·-·- ·-· -·--·--· 16
Instaiiation of 1100-lb. and 600-lb. Bombs on XLB-1 Airplane· --·-····-·--·-· ·------·---·· -------- -·- · 16
Pyle-0-Lite Floodlight ------·------··- ·-·--·-··--·- ·-· ·· --- -- ------ --·-··- ·---·- --------------- ·---- ·-- ·------- ----- -------------- -- 18
Curtiss R-1454 Radi11J Engine with Type "M" Cylinders -··----- ·--· ··-- ····-·-- ·--- -·--·····- ·------·-·- 20
New Stromberg NA-Y5D Carburetor for Curtiss D-12 Engine ---····- ·---- ·-· ·--- --- ·--- ·-···-·-·-· 22
Sectional View of Stromberg NA-Y5D Carburetor (Service Test Model) .... ---···---·- ·---·-· 23
Stromberg NA-Y5D Carburetors Assembled with Air Intake and Manifolds...... ... ..... 23
Splitdorf Model VA Magneto ---· --· -- -··· ·--·---- --- -- -· ·-· ·- ··------ -- -- ----·--·---· ·-- ---· -· -- ------- -·-· -- --· --·--· ·- ···· 24
Independent Breaker Mechanisms en Splitdorf VA Magneto ...... ..... ......... ------·--·-···· ·---·-·-· 2!i
Basket Weave Covering of Woven Plywood Wing (Forest Products Laboratory).... 27
Stromberg N A-Sl 2 Carburetor for Packard l A-2500 Engine...... .... .... ..................... .... ..... 30 •
Stromberg NA-S12 Carburetor with Halves Par.ted showing Double J ets and F loat
Chambers --·--···· -···· ··- -·-- -··-· --·--·---·-------····· ··-----·· -··----··- --- -··-- --· ----·- -· ···--· ··--· -···-· ····-·---· ···-··--·-·-- ·-· 31
Valve Arrangements of Cylinders Used in Study of Induction Losses in Aircraft
Engines ·------- --- ··· ··· ···· ----·-- ·· ··-·· ·-----·--·-·- -- ··--- ·-·----··--·- ···--· ---·-····· ·- ··------· ·····-· ··· 33
Zenith ED-52 Carburetor for Supercharged Liberty Engine ····-----·---·--- ·-··-· --------------·· ·- 36
Zenith ED-25 Carburetor with Halves Parted ....... ·--··-----·-·--- ·-·- ·····-· ·--------------·---· 37
6 T E C H N I C A L B U L L E T I N N n. 4 5
DOUGLAS OBSERVATION 0 -28 (NIGHT-FLYING WITH DUAL CONTROL)
Liberty "12" Eng ine.
(This airplane has been reserved for use of the Ch ief of Air Service )
AIRCRAFT DEVELOPMENT
ON ENGINEERING DIVISION PROGRAM
AIRPLANES
Douglas Observation Airplanes.
Fol lowing adoption of the Douglas X0-2 design by the Army Air S-ervice to supersede the
obsolescent DH-4B as the standard service type observation airplane, the Douglas Company of Santa
l\Toni ca, California, was given a contract for seventy-five airplanes, Of this number, seventy were
to be powered with Liberty "12" engines and the remainder with Packard l A-1500 engines, The
contract also provided for the submission of a skeleton airplane to the E ngineering Division for
static test prior to construction of the production articl es, DeliYeries were scheduled for comple­tion
during the fo re part of 1926,
T he production articles follow the same general design and type of construction used in the
sample airplane, lVIodel X0-2, which participated in the competi tions held at McCook F ield toward
the close of 1924, The model designations for these airplanes, as assigned below, are in accordance
with the new classification for observation types a nd with the manner in which these articles are
equipped ,
Liberty Engine,
46--0-2 Douglas Observation ( Standard)
18-0-2A Douglas Observation (Night Flying)
6--0-2B Douglas Observation (Night Flying-Dual Control)
Packard IA 1500 Engine,
3-0-7 Douglas Observation (Upright Engine)
*1-0-8 Douglas Observation ( Inverted E n gine)
1-0-9 Douglas Observation (Geared Engine),
*Subsequently changed to take Curt iss R-1 454 ra dial eng ine,
DOUGLAS OBSERVATION 0-7 WITH PACKARD lA-1500 ENGINE,
T E C H N I C A L B U L L E T I N N o. 4 5
T he production model embodies many refin ements which find outward expression in that trim
appearance and simplicity of design so characteri stic of the sample airplane submitted in the compe­titions.
Among the noticeable changes affecting the general appearance of the production model are
the fo llowing: new nose cowling and radiator shutter s, double wires in the lift truss of the main wing
cellule· and the addition of an aux iliary tail skid beneath the rudder post. Structural improvements,
although largely of a minor nature, have been made to increase the strength of certain vital parts
rather than to effect any radical change in design. J\ 11 ferrous parts are protected against co r­rosion.
particularly the steel tubing which af ter ass~mhl y was flu shed on the in side with warm linseed
oil under pressure. All wood parts as well as the exterior surface of the tubing are protected by
spar varnish. \!\Tith regard to equi pment, in stallations have been made with a view to increasing ac­cessibi
lity and ease of maintenance. Controls, armament. in str uments and other special eq ui pment
have been arranged to affo rd utmost convenience in manipulation and reliability to fu nction.
In the original specification for the production arti cle equipped with Liberty engine and large
wi ngs of 411 square feet in area, the gross weight was limited to 5005 pounds. T his figure pro­vided
for a military load of 1044 pounds including special armament and equipment and a maxi­mum
combu stible load of 11 31 pounds comp ri sing 170 gallons of fu el, as contained in two 60-gal­lon
cl roppable tanks in the lower wing and one SO-gallon reserve tank in the fu selage, together with
commensurate oil capacity. T hru subsequent revisions in the contract, however, the gross weights
of the various models were decreased considerably from the afore-mentioned limit and varied in
accordance with the manner in whi ch each art icle was equipped. T hese revisions also affected the
layout of the fu el system in that the SO-gallon reser ve tank was replaced by a 40-gallon tank in the
fuselage and a 10-gallon gravity tank in the upper wing, leaving the total capacity of the system
unchangecl.
A II production ar ticles including those equipped with Packarcl engines a re of the same overall
dimensions. T he gross weights of the cliffe rent models, however, vary in accordance with their re-
~I
PILOT'S COCKPIT IN DOUGLAS 0 -28.
A I RC R A F T D EVE L O P MENT 9
spective military loads, the kind of engine used and the special equipment. The normal combustible
load of 798 pounds remains constant for all mode ls. On the night-fl ying articles, the wing tips are
made detachable to accommodate landing lights.
The standard production a rticle. Model 0 -2, which is designed for day-flying, carries a normal
militai·y load of 955 pounds. This load con stitutes the fo llowing : crew of two; one interchangeable
synchroni zed machine gun, either .30 or .SO caliber. mounted forward; two .30 ca li ber machine
guns on rear gun ring ; radio apparatus in cluding receiving. transm1tting and interphone sets; K-3
automatic camera in stallation; and other standard equipment for thj s type of airplane. In addi ­tion
to the normal military load, provision is made for ca rrying a special load of armament.
In the 0-2A, which is specially equipped for night-flying, the normal military load is 992
pounds. T his articl e carries p ractically the same equipment as the 0-2 model except that special
provision is made for the in stallation and operation of electric landing and running lights, wing tip
and airways parachute flares, and other signalling devices.
In addition to night-flying equipment, the 0-2B article is pr O\· icled with parti al dual control in­stallation
in ord er that it may be piloted from either cockpit. For thi s purpose, the rear cockpit has
been equi pped with conventional stick and rudder bar , engine control unit, navigating in struments
and some engine instruments, but there is no tachometer, fu el control cock, ignition cut-out or
radiator shutter control provided. Since no armament or bombing equi pment is carri ed in this air­plane,
the military load totals only 695 pounds. Special equipment includes two-way radio and in­terphone
communication, wing tip and airways parachute fl ares, and electric landing and running
lights complete with switch panels.
The 0 -2B has been flown to McCook F ield where a special in spection is being per formed to
determine the fun ctioning of certain in stallations and special equipment. preparatory to its release
to the service.
OBSERVER'S COCKPIT IN DOUGLAS 0-2B SHOWING DUAL CONTROL INSTALLATION.
10 T E C H N I C A L B U L L E T I N N o. 4 S
The articles with Packard engines, Models 0-7 and 0-9, are similar to the standard 0-2
model in all respects with the exception of the engine section which conforms to the respective de­mands
of the upright and geared engine installations as indicated by their model designations. The
fir st of these, the 0-7, has been received at the Di vision for inspection and performance test.
The 0-8 airplane will be equipped with a Curtiss R-14S4 ai r-cooled radial engine, since the in­verted
Packard engine in stallation has been found inadvisable.
In connection with ground attack aviation, specifications have been prepared covering the con­version
of one night-flying article, for this purpose. The modifications provide for the in stalla­tion
of four .30 caliber Browning machine guns entirely within the wings in addition to the syn­chronized
and flexible guns already provided. The wing guns will be remotely cont rolled by the
crew.
Huff-Daland Light Bomber Placed in Production.
Exceptional performance displayed by the XLB-1 has warranted placing this new type of
single engined light bombardment airplane in production. Accordingly H uff, Daland and Com­pany,
Inc., of Bristol, Pa .. which developed the design , has been awarded an order for ten ai r­planes
to be known as Model LB-1. These airplanes will be placed on service test.
The experimental model XLB-1 met contract requirements in practically all respects. In the
acceptance tests conducted at the Division this airplane with an 800-h. p. Packard geared engine
attained a high speed of 124.5 miles per hour and a service ceiling of lS ,500 feet, thereby exceeding
the performance requirements for speed and ceiling by S ,Yi miles per hour and 1 SOO feet respectively.
These results were obtained with a gross weight of 10.014 pounds. Of this amount 4632 pounds
constituted useful load representing the equivalent of a full complement of armament" and equip­ment,
a crew of three, a supply of fuel and oil sufficient for S ;-:; hours' flight, and a bomb load of
two 600-lb. bombs.
On October 13, 1925, the XLB-1 airplane won the Detroit News Air Transport Trophy Race in
the International Air Races at Mitchel F ield averaging 119.91 miles per hour over a 120-mile
triangular course.
Several important changes will be incoqXJrated in the production models, the most extensive of
which will be the increase in useful load as recommended by the Bombardment Conference at Kelly
F ield last summer ( 1925) . This involves an in c-rease in bomb capacity to accommodate a normal
load of four 600-lb. bombs instead of two 600-lb. bombs as formerly carried and an increase in
crew from three to four persons, the additional man to serve as radio operator and floor gunner in
the rear. To effect these changes necessitates a complete rearrangement of the fuselage and an
enlargement of the bomb bay. The engine mount will also be redesigned to preclude weaving with
large geared engine, and the radiator will be changed from the nose type to the tunnel type with
concordant changes in the cowling. Because of the insistence of the service for dual controls, the
pilot's cockpit will be widened to accommodate two men seated side by side, although this ar­rangement
will be somewhat cramped. The area of the rudder will be increased and more balanced
portion added to compensate for same. Two fixed guns, remotely controlled. will be placed in the
lower wings. All of these changes are being incorporated in a mock-up under separate contract,
preparatory to their inclusion in the production articles.
A brief description of the XLB-1 airplane was published on page 9, Tecli11ical Bulletin No. 43.
The standard performance tests have not yet been concluded.
Boeing Pursuit Airplanes.
A production model P\V-9 pursuit airplane has been receiYed at the E ngineering Divi sion for
in spection and test. This airplane is one of the SS articles being manufactured by the Boeing Air­plane
Company, Seattle, \Vashington, under three production orders awarded by the Army Air
Service for 12, 18 and 2S airplanes respectively. Although fo llowing closely t he same general de­sign
and dimensions as the first experimental article deli vered to the Di vision two years ago, the
pr-oduction model embodies many refinements as evidenced by its neatly trimmed appearance and
its excellent flying qualities. One of the most noticeable changes is the adoption of the split-ax le.
oleo-pneumatic type landing gear in place of the straight type faired axle of the earlier model.
AIRCRAFT DEVELOPMENT
BOEING PURSUIT PW-9 (PRODUCTION ARTICLE)
Curtiss D-12 Engine.
11
One of the production articles on the second order has been selected for experimentation with
the Packard supercharged engine, under the mode 1 designation "XP-4." T his airplane will be
modified to accommodate the in stall ation of the 500-h. p. Packard l\Todel l A-1500 engine equipped
with a 20.000-foot side type supercha rger and a fo nr-bladed metal propeller, 9 feet in diameter. The
installation will necessitate an increase in cooling surface and a rearrangement of the wings and
equipmen t to presen·e balance. Concurrent with these changes it is proposed to mount remotely
controlled machine guns on the wings of the airplane. Provision will also be made in the design
for the installation of radio and night-flying equi pment. A high speed of 175 miles an hour at
an altitude of 20.000 feet is anticipated.
The principal characteri stics of the production Boeing Y\\'-9 airplane are as follows:
Type ....... . .................. . . ...... ...... ... .... . .... Pursuit biplane
Power plant ...... . . . ... . . . . . ... ... ... . .. ...... . ......... . Curti ss D-12
Owrall span ... . ............ ... .... .. .. ... . .......... .. .. 32 ft. 1 in.
Overall length . ..... . .. . . . . . . ........ . .. . ... .. ..... . . . ... . 22 ft . 10;0 in.
Overall height .... . .. ..... . .. .......... . ... ... .. .. . ... . . .. 8 ft . 8 in.
Supporting area .... . ......... ......... . ... . . . ... . . . ...... 241.7 sq. f t.
Gross weight . .. . ...... .. ................... ... ... . ... . .. . 3020 lbs.
Useful load .. .. .. ...... .... . ....... . . . . ... .... . . ... ...... 854 lbs.
H igh speed at ground . . ..... . ...... . . . ............ ... ..... . 165.5 rn. p. h.
Rate of climb at ground ... ..... . . ..... . ... . .... . . . .. . ...... 1710 ft ./ min.
T ime to climb to 10.000 feet .... ... . ....... .. ............. ... 7.9 min.
Service ceiling .... .. ... ... ........ . .. . .. . .... . .... . ....... 20175 feet
Recently the Boeing Airplane Company has been granted the use of certain governrnen t-ovvned
f'q uipment for the dcveiopment of an entirely new type of pursuit airplane about the Packard
Model l A- 1500 in verted type engin e. Besides the engine and accessories, the loaned equipment
includes two remotely co ntrolled machine gun s, several late type in struments and other accessories
incident to modern pursuit aircraft. In lieu of the use of thi s equi pment the Boeing Company
agrees to design, construct and test the proposed airplane at its own expense and subsequently
furn ish the Engineering Division with a fu ll and comprehensive report of its performance.
X0-6 All-Metal Airplane Passes Static Tests.
Static tests have been completed with satisfactory results on the static test model for the new
all-metal X0-6 observation airplanes to be built by the T homas-l\1orse Aircraft Corporation .
Ithaca, N. Y.1 under experimental contract. In these tests the wings and fu selage sustained the
12 T E C H N I C A L B U L L E T I N N o. 4 5
required load factors without failure, and the Vickers' oleo landing gear withstood a drop of 65
inches under half load or a drop of 24 inches greater than that required. As a result of the tests per­mission
has been granted the contractor to proceed with the construction of the flight test model, in­corporating
therein a number of changes to improve serviceability and maintenance. In order that
these changes might be embodied in the design it w:as necessary to raise the contract requirement
for weight empty from 2900 pounds to 2960 pounds. It was also cleciclecl to adopt the oleo-pneu­matic
type of shock absorber as standard equipnwnt on these airplanes in place of the conventional
elastic cord type. The desirability of using oleo-pneumatic units is cine to the fact that this type of
shock absorber gives a minimum rebound in landing and requires vcrv little maintenance.
The X0-6 all-metal observation airplane, five of which are on order, follows a standardized
two-seater biplane design based on the Douglas observation airplane X0-2 which has gone into
quantity production.
Bids Received for Heavy Bombardment Airplane (Monoplane Type).
Bids were received by the Army Air Service at McCook Field on October 22, 1925, for the de­sign
and construction of a heavy bombardment airplane of the monoplane type. Out of eleven air­craft
designers and manufacturers to whom the circular proposal had been sent, only four re­sponded.
These were as follows:
Consolidated Aircraft Corporation,
Cox-Klemin Aircraft Corporation,
G. E lias and Bros., Inc. ,
H uff, Daland and Company, Inc.
The specifications call for the ex.perimental development of one heavy bombardment single­engined
airplane of monoplane construction, built around the new 1200-h. p. air-cooled "X" type
engine now under development by the Allison Engineering Company or about two 800-h. p. Pack­ard
l A-2500 engines. In addition to the regular navigation equipment and defe nsive ordnance, the
proposed bomber will be capable of carrying a crew of four , a normal bomb load of 5,700 pounds
and a supply of fuel sufficient for eight hours' flight at 10,000 feet altitude.
Inasmuch as much preliminary engineering work is required before determining the final de­sign
of wing structure, .upon which the success of the project depends, no decision has been
reached as to the ultimate design of airplane to be built. In this connection one of the contestants,
Huff, Daland and Company, has been contracted with to rework thei r design and furni sh certain
skeleton wing structures and a wind tunnel model for test.
Shock Absorbers.
A preliminary report has been prepared on methods of designing vanous types of shock ab­sorber
units from data obtain ed in impact tests of landing gears at the Engineering Division. The
methods recommended for determining the loads required in these tests are developed in both
anal ytical and graphical forms for the following arrangements:
a. No shock absorber used (tire only)
b. Rubber in tension.
Another report will deal with rubber in compression and with oleo gears.
In connection with oleo gears, shock absorber units of this type have been designed for in­stallation
on the Douglas C-1 transport and 0-2 obser vation airplanes. The design of these gears
is based on the in stallation and test of a model in stallation on the Douglas X0-2 airplane at the
Division.
Design Study for Night Observation Airplane.
A design study of a night observation airplane powered by two \!\!right 200-h. p. Model J-4
radial engines has been initiated. This study will cover construction and test of a wind tunnel
model and performance calculations on the possibility of flight with only one engine. Preliminary
sketches showing various arrangements, together with a three view layout of the proposed design,
have been made.
AIRCRAFT DEV EL OPM ENT 13
AIRSHIPS AND BALLOONS
New Airship for Primary Training, Model TF-1.
Authority has been granted by the Chief of Air Service to design and construct a small non -
rigid primary training ai r ship of about 52.000 cubic feet capacity. The TF-1 airship, as the new
type is designated, is designed for primary training for student pilots and for coast patrol work.
It will replace the present TA air ship for primary training purposes, thereby effecting greater
economy in construction and operating cost by reason of its greatly reduced volume.
This airship will he of a single-engine pusher type, using the Lawrance L-4 engine, vvith pro­\
·ision in the design for the contemp lated in stallation of the new 60 h. p. Rickenbacker 5-cylinder
air-cooled engine, in event this engine proves satisfactory. The control car will be of all-metal con­struction
similar to that used in the TE airship car. The designs for the envelope and the control
surfaces have been completed and the purchase of these parts requested, but the design for the all­metal
car will not be fini shed before April 1.
All-Metal Car for TC Airship.
The saving in weight resulting from the application of the all -metal car to the non-rigid airship
has led to the design of an all-metal car for the TC airship to replace the present semi-monocoq ue
plywood cars with which this a irship is now equipped. By a change in material and design of the
car, it is expected to reduce the structural weight approximately 800 to 1000 pounds. The pro­posed
design will incorporate all improvements that have been recommended as a result of ser vice
test of similar equipment during the past five years.
Improved Helium Inflation Equipment.
Improved eq uipment for helium inflation has been de veloped by the Engineering Division to
provide a quickly applied, gas-tight means of joining standard infl ation tubes used in inflating air­ships
and balloons. This equipment is designed to di spense with the present practice of "tying off"
the tubes-a rnethod that causes a breaking-clown of the gas film with resultant loss of gas. A
complete outfit consists of fi ve units as fo llows:
One Inflation Sleeve with Cover, T ype A-3
One Inflation l\1an ifo lcl , T ype B-1
Three Inflation Tube Connectors, Type A-1
Each infl ation tube connector is fitted with seventy-five feet of standard inflation tube. 10-1 / 2
inches in diameter.
The inflation sleeve is conical in shape, being 10-1 / 2 inches in diameter at the small encl and 1S
inches in diameter at the la rge end. The small encl of the sleeve is fitted with a cluralumin thimble
which connects with a similar thimble on the inflation tube. The large encl of th e sleeve is attached
to the envelope. The object in using a conically shaped sleeYe is to allow the sleeve and thimbl e.
after the sleeve has been tied off and di sconnec ted from the inflation tube, to be pushed in side
the envelope and the opening covered with a standard 18-inch inflation sleeYe cover.
HELIUM INFLATION MANIFOLD, TYPE B-1.
14 T E C H N I C A L B U L L E T I N N o. 4 5
T he inflation manifold is abo cone-shaped. The large end is fi tted with a seat to receive the
connector on the encl of the inflation tube, whereas the small encl branches into twelve leads of
hose for attachment to a like number of gas storage cylinders, the hose being secured to the
cylinders by mean s of wing nuts. The hose connection at the mani fo ld end is provided with a
check-valve to prevent loss of gas clue to hack pressure in changing fr om one cylinder to another
during inflation. As a precaution again st static, a wire about 1/ 32 o{ an inch diameter is passed
thru the hose and soldered to each encl connection to form a ground.
HELIUM INFLATION TUBE CONNECTOR, TYPE A-I.
The inflati on slee1·e on the envelope is connected with the inflation mani fo ld from the gas
cylinders by means of a 75-foo t length of standard 10-1/ 2 inch inflation tube. This tube is fitted
with duralumin thimbles or connectors, one in each end. Connection with the envelope is made by
inserting the thim ble in the inflation tube and the thimble in the small encl of the slee1·e into a collar
containing soft rubber seats again st which the thimbles are clamped by means of exerciser cord
hooked over alternate lugs on their peripheries. Connection with th e gas cylinders is effected by
clamping the thimble in the opposite end of the inflation tube again st the seat in the mani fold, this
same method of clampin g pro viding a gas-tight joint.
The equipment is designed to be electro staticall y safe and gas-tight under all conditions. A l­though
the units are of rugged and durable construction, they are so light and easily handl ed that
they may be quickly connected or di sconnected without loss of gas. Four complete sets have been
procured and sent out to the service for test.
Helium Purification Railway Unit.
The construction of a railway unit fo r helium purifi cation is in prog ress in the lighter-than­air
shops of the E ngineering Division at \Vrig-ht Field. This unit as planned in the Office. Chief
of Air Service. consists of a mobile helium purif ying plant capable of being transported by rail ­road
and of being put into operation at any Air Service station or elsewhere in the field in emerg­ency
cases.
T he plant which has all the necessary equipment fo r puri fy ing helium gas that has become im­pure
from continued use in airships or from other causes, is housed in a specially built rail road car.
It has a capacity of 5,000 cubic feet of impure helium per hour continuous service. The gas is
purifi ed by what is known as the liquefaction process, to a purity of 98 per cent or better . T he
power for running the compressors is f urni shed by two 60 h. p. electric motors which can be oper­ated
on either a 220-volt or a 2300-volt circuit, operation hy the higher voltage being made possible
through the use of a special transformer in stalled in the car .
AIRC R AFT DEVELOPMENT 15
Fabrication of various pieces of special equipment is being clone at McCook Field , and the as­sembly
of the complete unit is expected to be completed at \Vright Field in March, 1926.
Erection of Mooring Tower at Scott Field Delayed.
The Aircraft Development Corporation of Detroit, which has a contract for the erection of a
steel mooring tower at Scott Field, has been granted an extension of time for the completion of the
project. The delay was occasioned by changes in the mooring arrangement to accommodate the
new RS-1 airship, the details of which were furnished by the Engineering Division.
The tower is to be 175 feet high as measured from the ground to the mooring cone receptacle
at the top. It will be of the fixed self-braced tubular smokestack type, measuring 11 feet in diam­eter,
with a splay of 18 feet at the bottom. T he superstructure will rest on a concrete base, 40 feet
in diameter by 10 feet in depth. At the base of the tower a small Truscon steel covered building,
30 feet long by 28 feet wide, will be erected to house the gasoline-electrical driven generator set.
transformers, winches, gasoline and water pumps and other equipment.
Redesign of Barrage Balloon.
\Vork has been started upon the design of an improved type barrage balloon to be smaller than
the first model which failed to meet requirements. In the redesigned model the fo llowing changes
will be incorporated:
a. Volumetric capacity will be reduced from 24,000 cubic feet to 15,000 cubic feet.
b. Air-fi lled lobes will replace the dilatable gas-fi lled lobes used in the fir st design.
c. The lobes will be stiffened by a system of fabr ic diaphragms.
d. Expansion will be obtained through three longitudinal di latable gores.
e. The envelope will be made of light single ply fahric, not over six ounces per square
yard in weight.
The envelope and lobes are being fabr icated by the Goodyear Tire & Rubber Company from
cloth furnished by the Government. It is expected to complete the construction and test of this
balloon in the early part of April, after which data will be prepared for procurement of service test
equipment.
ARMAMENT
Investigation of 0-2 and LB-1 Airplanes for Ground Attack.
The possibilities of installing armament on the Douglas 0-2 observation and the H uff-Dalancl
LB-1 light bombardment airplanes for ground attack purposes are being investigated. To convert
the 'planes for this purpose involves the mounting of remotely controlled Browning machine
guns, together with the necessary ammunition boxes and other accessories, in side the wing as dis­cussed
on page 28, T ech 11ical Bulletin No. 44. The investigation covers construction and test of a
suitable gun mount and ammunition boxes conforming to the airfoil section as well as a test to
determine the strength of the wing spars in that vic;inity.
New Bomb Rack for Production LB-1 Airp]anes.
It has been found necessary to rework the type D-2 internal bomb rack to fit the new pro­duction
LB-1 (light bombardment) airplanes now under construction at the plant of H uff, Daland
& Co., 1nc .. Bristol, Pa. T his change is occasioned by the fact that the new production airplanes
have a wider fu selage than the original XLB-1 airplane. The work has been completed, and the
rebuilt racks forwarded to the manufacturer for installation purposes.
The extensiveness of the changes required to rework the tvpe D-2 bomb rack to fit the new
production LB-l 's made it advisable to draw up an entirely new design of rack for these airplanes.
One of the new racks is being built at the Division to determine the workability of the drawings for
production .
The new production type D-2 internal bomb rack consists of two hangers capable of carrying
three bombs each-either 100-lb., 300-lb. or 600-lb. sizes or combinations of the same. However,
only two 600-l b. bombs can be accommodated on each hanger at one time owing to the relative size
of the bombs and the limited distance between the bomb stations. The bombs are attached to the
J I) T .E C H N I C A L B U L L E T I N N o. 4 5
BOMB RACK D-2 IN XLB--1 AIRPLANE SHOWING BOMB HOIST C-2 IN POSITION FOR RAISING BOMBS TO
INTERNAL RACK POSITIONS.
rack by means of the standard type B-4 bomb shackle or the new improved type B-5 shackle which
is described on page 17, Technicnl Bulletin N o. 43. E ach shackle incorporates it s own arming
mechanism. The mechani sm which trip s the bombs is so a rranged that it skip s all empty bomb sta­tions
c>.utomatically, thereby eliminating any confusion which might arise in releasing the bombs in
different combinations. The rack weighs only for ty pounds as it is built almost entirely of dura­lumin
. It has a high facfor of sa fety with maximum bomb load. The upper extremities of the
rack pro vide a support fo r the internal type bomb hoist, whereas the lower ends provide an attach­ment
fo r an adapter-a bracket fo r attaching one or two external type iJomb racks such as the C-2
and C-3 for carrying 1100-lb. bombs. T!te rack also serves as a support for the type I-I -4 ex­ternal
bomb rack which carries either a 2000-lb. or a 4000-lb. bomb.
INSTALLATION OF llOO-LB. AND 600-LB. BOMBS ON XLB-1 AIRPLANE
(The bombs are carried on C~3 external racks suspended from the D~2 internal rack by m eans of adapters.)
AIRCRAFT DEVELOPMENT 17
EQUIPMENT
Night Flashlight Photography.
After several attempts to take night aerial photographs by flashlight, the first successful test
was made over McCook Field on the night of October 30, 1925. In this test a photograph was
made from an altitude of 2400 feet, which depicted the various buildings, shops, hangars, roads,
trees, and even automobiles traveling the highway bordering the field. The photograph was taken
with a K-3 camera in the night-flying lVIartin Bomber from which a torpedo containing 28 pounds
of flashlight powder was released. The camera was fitted with an ultra high speed lens, a Carl
Zeiss f/2.7, imported from Germany. The torpedo used in the test was manufactured by the U n­excelled
Mfg. Company of Cincinnati, Ohio, in cooperation with the Division. The torpedo
weighed 50 pounds, and was attached to a standard flare parachute. It was so designed that it
could be released with a timed fuse when the photographer is over his objective. By timing the
torpedo to explode eight seconds after release, it was estimated that the fla sh would occur ap­proximately
1000 feet to the rear and 150 feet below the towing photographic 'plane. However, in
this test, the fuse burned for 16 seconds for some unexplained reason, and the flash took place
2000 feet to rear and 300 feet below the 'plane, causing the exposure to be made on the edge of the
illuminated area.
Following these experiments a number of daylight tests were made at the Division with timed
fuse s, and some new torpedoes were manufactured by the U nexcelled Mfg. Company for use in
subsequent tests at Rochester, N . Y.
Night tests over that city were conducted early in November in conjunction with the Eastman
Kodak Company, as this concern possessed a research laboratory equipped with special facilities for
making photometric tests. This equipment included a special photometer, a very sensitive instru­ment
for measuring the intensity of light. The use of such an instrument in these tests was especial­lv
desirable in order to measure the light given off by the fla shlight torpedo. since from this data
it would be possible to predetermine the relative amounts of flashlight powder required to obtain
satisfactory photographs at various altitudes.
The tests at 1\ochester were highly success ful , exposures being made fr om a night-flying Mar ­tin
Bomber airplane equipped with several types of aircraft cameras and two flashlight torpedoes.
The cameras, seven in all , included the Army types, K-1, K-3 and Gaumont, all equipped with high
speed lenses. A motion picture camera was also carried to record the speed of the fla sh. The two
torpedoes, each containing 50 pounds of special flashlight powder. were equipped with parachutes
of the same type as that used on the standard airways parachute flare, and provided with double
time fuses. f\ t a prearranged signal from observers on the roof of a tall building at the Eastman
factory, on which the photometric apparatus had been mounted. the first torpedo was dropped
from an altitude of about 3000 feet for which the exposures had been set. The flash, which lasted
only 1 / 20 of a second- too swi ft for the eye to record-gave excellent results. much better than the
second and slower flash lasting 1/ 2 of a second, which followed a few minutes later.
Remarkable definition was obtained in the resulting photographs. Rivers, buildings. highways.
bridges, smoking chimneys, and other objects were delineated almost as clearly as in daylight ex­posures.
All exposures in this test were made upon hypersensitized panchromatic film manufac­tured
by the Eastman Company. The area photographed covered approximately three square miles.
The success of these experiments is of g-reat military significance, particularly when viewed in
connection with the new process known as "Quick-work" photography in which aerial photo­graphs
taken in flight may be developed and finished within a few minutes without landing.
Since the Rochester test a more efficient flashlight powder has been developed for this work.
and experiments will he continued with six new hornbs or torpedoes of later design and some new
high speed lenses that have been ordered purposely for this work.
Kryptocyanine Film.
Aerial photographs have been made by the Engineering Division using a new film sensitized
with a dye known as "Kryptocyanine." This film photographs thru the action of infra-red light
only, and if found fea sible for service use will permit great haze penetration-a quality so essential
in high altitude photography.
The film is manufactured by the Eastman Kodak Company, Roch.ester, N . Y.
l .s T E ·C H N I C A L l3 U L L E T I N N o. 4 5
Transmission of Aerial Photographs by Radio Proposed.
In view of the success in tran smitting aerial photographs over telephone wires as recently con­ducted
by the Engineering Division in collaboration with the American Telephone and Telegraph
Company, an attempt will be made to transmit aerial photographs by radio. For this purpose two
Jen kins "Junior" machines have been procured.
Pyle-0-Lite Floodlight.
A sample model of the latest type of floodlight projector has been ~ubm itted by the Pyle­National
Company, Chicago, for inspection and
test. The "Pyle-0-Lite" floodlight, as this pro­jector
is called, represents the latest development
by this company in the short focal length reflector
for use with diverging or non-diverging lens. This
reflector has a compact cone-shaped body. so
mounted in a swivel frame that it may be fixed in
any desired vertical or horizontal position. It is
fitted with a convex lens door , 23 inches in di­ameter,
which opens upward giving access to the
glass reflector and incandescent lamp. The top of
the door is fitted with a vizor for shielding the lens
and also the eyes of the operator when adj usting
the floodlight. In addition to being a fi eld flood­light,
the "Pyle-0-Lite" is also designed for in­stallation
on a special truck for mobile purposes.
Short Type Airplane Landing Light.
A modified airplane landing light with short
streamline body, known as the Type A-3. has been
constructed for use on short cord wings like those
on the Boeing and Curtiss pursuits. Six sample
lights of this type are being made for service test.
In connection with this development se\'eral
new types of elliptica.1 and parabolic reflectors and
special lenses are being in vestigated with a view
to incorporating a new and more efficient type of
reflector in the airplane landing light.
Changes Proposed to Increase Life of Aircraft
Storage Batteries.
Preliminary investigation in connection with
PYLE-O-LITE FLOODLIGHT. the standardization of storage batteries discloses
that the life of the present aircraft storage batten r
might be increased from ~S to SO per cent by decreasing the capacity 70 per cent and the weight 8
per cent. There would be no sa\'ing in the overall dimensions of the battery, however. Several
batteries using heavier separators will be obtained for check test.
Inertia Starters.
It has been determined that the T ype C-5 inertia starter submitted hy the Eclipse Machine
Company for examination and test can be in stalled in any standard airplane. with slight modifica­tions
of the fi rewall where necessary. In any in stallation on present engines. however, a special
clutch will have to be mounted on the crankshaft.
The T ype C-5 starter , ten of which are on order with the Eclipse Machine Company, is of the
combination hand and electric operated inertia type. The inertia portion , which contains a fl ywheel
of small diameter, weighs about 27 pounds. whereas the electric m.otor which is removable weighs
only eight pounds. Execs ive fri ction observed in the first experimental unit submitted for test
AIRCRAFT DEVELOPMENT 19
has been largely eliminated by the use of ball bearings at the vital points. The extent to which this
friction has been overcome is illustrated by the fact that it is now possible to obtain 40 accelera­tions
to 12,000 revolutions per minute of the flywheel from a Type C-1 storage lJattery as against
14 accelerations before the ball bearings were installed.
For large aircraft engines, there is being developed an electric inertia starter of 1200 foot­pounds
capacity. It is believed that a starter of this capacity will be capable of handling all engines
from 750 to 1200 horsepower under adverse weather conditions.
New Instruments.
Three new instruments-an airspeed indicator with scale of 0-250 m. p. h., a combination en­gine
gage incorporating a 200-lb. oil pressure gage, and a 3000-r. p. m. tachometer-have been
procured and tested for use in pursuit aircraft. All of the instruments are of the vertical scale typP.
and have a higher range of indication than is normally provided in service type instruments.
SCR-133 Radio Set Control Box Made Smaller.
The control box for the airplane radio set SCR-133 has been redesigned to accommodate pur­suit
aircraft. It was found that by rearranging parts the box could be made much thinner, there­by
reducing its bulk about one-half. Following flight tests of the redesigned box in pursuit aircraft,
work will be started on redesigning the tuner unit with a view to decreasing its size also.
Portable Filling Device for Cross-Country Airplanes.
Tests have been made on portable servicing equipment for use on cross-country airplanes.
This unit consists of .a pump, a nozzle, and a filter , together with suitable hose connections for at­taching
to the standard fuel storage drum. The pump used in this experimental equipment is of
the hand wabble type of 1000 gallons an hour capacity. The complete outfit as at present designed
weighs about 15 pounds.
Several modifications will be necessary before the er1uiprnent is ready for service test.
POWER PLANTS
Progress on 1200-h. p. "X" Type Engine.
Jn collaboration with the Alli son Engineering Company, of Indianapolis, in the development
under experimental contract of the large "X" type 1200-h. p. :'.\fodel X-4520 air-cooled engine, the
Engineering Division is conducting a series of dynamometer tests to determine the final design for
the bearings and cylinders of this engine. The work at the Division involves the design and con­struction
of a hearing test rig and the design , construction and test of the single cylinder. The
bearing test rig has been assembled. and the tests on the bearings begun. After 22 hours of testing
at full speed a knock developed. Upon investigation it was found that the spacers and bearing
adapters had galled on the shaft. Accordingly these parts were removed, and fabrication was be­gun
on replacement parts made of case hardened steel.
For the cylinder tests, several sample assemblies are being made up by the Allison Company
from head castings furnished by the Division . These cylinders will be tested in the McCook Field
laboratory where a universal test engine has been fitted with a special crankshaft to accommodate
them.
The proposed engine will be of the "X" type, its 24 air-cooled cylinders being arranged in
four banks of six each with 90 degrees between banks. T his arrangement gives equal firing inter­vals
and uniform air cooling. The bore and stroke, Sy,J: inches by 774 inches, give a total piston
displacement of 4520 cubic inches, from which the engine derives its model designation. The
cylinder design ~s practically identical to that of the type "M" cylinder previously developed by the
Engineering Division. The crankshaft is designed with hollow crankpin and main journals of
large diameter combining light construction with maximum torsional rigidity. Plain bearings
will be provided in the rod and roller bearings on the crankshaft, the latter finding rigid support on
the thick webs of the tunnel type crankcase. Incorporated in the design as an integral part of the
engine will be a 10,000-foot gear-driven centrifugal supercharger of the suction type and a 2 :1 pro­peller
reduction gear. The former mechanism will be supplied by the General Electric Company
and the latter by the Allison Engineering Company under separate·purchase orders.
20 T E C H N I C A L B U L L E T I K N o. 4 5
The deli very of thi s engine. which had been scheduled for January, 1926, has been extended
for a period of six months in order to allow suffic ient time for working out the fin al detail s of the
design.
Development of Curtiss R-1454 Radial Engine.
F oll owing preliminary clynamometer tests at l\kCook F ield laboratory, the fir st experimental
:tl'Iodel R-1454 air-cooled radial engine was returned to the manu facturer, the Curtiss Aeroplane &
:tlfotor Company, for incorporation of Type "M" cylinders and other changes designed to improve
durability and performance. pon reassembly the master rod was placed at cylinder No. 7, a posi­tion
almost opposite its original location. and the revised engine returned to the Division fo r con­tin
uation of the SO-hour endurance test.
CURTISS R-1454 RADIAL ENGINE WITH TYPE "M" CYLINDERS.
(400 h . p. a t 1650 r.p.m.)
After 12 hours running at speeds varying from 800 r. p. 111 . to 1500 r. p. 111 ., and an additional
half hour at practically full throttle. the engine was removed from the torq ue stand for disas­sembly
and inspection of cylinders and pistons. These parts were found in excellent condition ex­cept
for slight scoring of the piston skirts. To obviate further sco ring circumferential oil grooves
were then made in the piston skirts in addition to the spiral grooves already provided, and the test
continued. At the end of 20 hours running, the master rod hearing flange cracked, and although
there was no indication of crankshaft fa ilure both master rod and crankshaft were removed and
returned to the manufacturer fo r repair. These parts have been recently received, and the en­gme
reassembled for test.
AIRCRAFT DEVELOPMENT 21
Fabrication of two of the five additional engines on order with the Curtiss Aeroplane & Motor
Company has been authorized by change order, but fabri cation of the three remaining engines will
be held in abeyance pending del ivery and test of the fir st engines. One of the R-1454 engines
will be in stalled in the new production model Curtiss P-lA pursuit airplane instead of in the Cur­ti
ss P-2 pursuit airplane as previously announced on page 7. Tech11ical Bulletin No . 43.
The in stallation of the R-1454 radial engine in the X0-2 observation airplane is under con­sideration.
and in this connection performance calculations are being made for comparison with the
performances already obtained with Liberty and Packard engines. If found desirable, the project
will be extended to include preparation of instaliation drawings and actual in stallation of the engine
in this airplane.
CHARACTERISTICS OF CURTISS R - 1454 ENGINE WITH TYPE " M" CYLINDERS.
"f\ Iodel designation .... .. . ... . . . .. . . . .. . .... . . .
T ype ................. . . . . . ..... . . . ... .... . . .
Status ..... .. . . ......... . . ... ....... . .. .. .. . .
J\Ianu facturer . . ...... . ......... . . . . . .. .... . . .
Cylinders .. ... . .. ...... . ...... .. ...... . ..... .
Bore .. . . . . . .... . .. . . .... .. .. . . . . ..... .. .. .. .
Stroke . ..... .. . ...... . ... . ...... ... ... ... .. .
P iston displacement ... ... . ... .... . . . ... .... .
Rated horsepower ....... ....... .... .... .. . . . . .
Compression ratio .. ...... . .. . .... .. . . .. . . . . .. .
!VIean effective p ressure .............. .. . . . .. .. .
*\ /I/ eight (approximate) .. . .. . ... . .... . .... . ... .
VI/ eight per rated horsepower . . . .... .. .. . . .... .. .
Overall diameter ..... . .. . . . ... .. . . .... . . . .... .
*Includes De lco ig ni tion , han<l s tarter and Type 1 L gene rator.
Air-Cooled I,iberty Engines.
R-1454
Air-cooled radial
E xperimental
Curtiss Aero. & Motor Co.
9, Type "l\!I"
5% inches
60 inches
1454 cubic inches
400@ 1650 r. p. m.
5.45:1
132.0 lb.jsq. in.
833 lb.
2.08 lb. / h. p.
54 inches
The first air-cooled Liberty engine developed by the E ngineering Division is still undergoing
developmental endurance tests to improve construction and reduce weight. T his engine, an upright
direct-dri ve model, has so far completed two SO-hour tests and about 25 hours of a third. The last
mentioned test is being run principally to determine the durability of sand cast pistons and triple
valve springs.
The first in verted type air-cooled L iberty engine which was ma nufactured by the Alli son En­gineering
Company on a contract for three engines, was installed in the Engineering Division
XC0-6 observation airplane for participation in the International Air Races at Mitchel F ield. Flight
performance data will be obtained on this moclei upon return of the airplane to McCook Field . An­other
air-cooled Liberty engine equipped with an epicyclic gear has also been received from the
/\lli son Company on the above mentioned order. This engine has been placed on dynamometer test.
Kingsbury Thrust Bearing.
The Kingslmry type thrnst hearing under de,·elopment to permit the use of crankshaft s with
integral propeller mounting fl anges is undergoing endurance tests on a Curti ss D-12 engine. Minor
lubrication difficulties have been encountered, hut the bearing is now operating satisfactorilv.
Investigation of Carburetor Metering Jets.
In an effort to corroborate data on carburetor metering jets with those obtained by the Navy
Department and carburetor manufacturers, the E ngineering DiYision has made check tests on a set
of special jets manufactured by the Stromberg Company for standard use. These jets have been
" flowed" under a SO-centimeter constant head and in a Brown & Barlow ftowmete r, and found to
giYe resul ts consistent with those obtain ed by the manufacturer. A similar set of these special jets
has been made up fo r use by the Division, and the original jets will be returned to the manufac­turer
for cali bration, after whirh they will be forwarded to the Navy Department for similar tests.
22 T E C H N I C A L n U L L E T I N N o. 4 5
New Stromberg NA-Y5D Carburetor for Curtiss D-12 Engine.
An .in vestigation of service difficulties encountered in the use of Stromberg NA-YS carburetors
on Curtiss D-12 engines in pursuit airplanes di sclosed a marked tendency of these carburetors to mal­function
during take-off on rough ground and in abrupt flight maneuver s. It was found necessary
to enlarge the float chambers and modify the fuel passages to correct the trouble. This resulted
NEW STROMBERG NA-YSD CARBURETOR FOR CURTISS D-12 E NGINE .
in the development of a new carburetor, the Stromberg NA-YSD, which has completed sati sfactorily
the experimental tests. This carburetor is now undergoing service test and, if satisfactory, will re­place
the i A-YS carburetors now in service. Views and description of the new Stromberg NA­YSD
are given herewith, but a detai led account of the development will be found in Serial No.
2602 mentioned on page 35 of this issue.
The new carburetor, several of which have heen placed on service test. is designated as _ foc\el
NA-YSD. It is a redesign of the NA-YS model. in which the standard Stromberg metering
system has been retained with slight modificati on. The chief differences between these carburetors
lie in the shape of the float chamber. in the construction of the float mechani sm and in the arrange­ment
of the fuel passages between the float chambers and with relation to the metering system. The
float chamber has been so shaped as to greatly increase the volume of fuel and decrease the volume
of air. In the inverted position, this shape of chamber maintains the fuel level approximately one­half
inch from what is normally the bottom of the chamber . By placing the fuel passages about
five-eighths of an inch above the bottom of the float chamber in the normal position, the fu el in­lets
are always submerged regardless of the position of the carburetor or of the fuel therein .
The fl oat mechani sm is of the same general design as the standard mechani sm. It consists of
two metal fl oats connected by a straight sha ft to operate one needle valve. T he connecting shaft
is so arranged, however, that no fuel or air connection is provided around the shaft between the
chambers. The chamber s, in turn, are connected near the bottom bv a cast-in brass tube and are
vented by means of a small common passage near the top. The rear fl oat chamber is connected
to the mixture control valve chamber thru a ball check valve which closes the passage when the car­buretor
is turned upside clown or when the vertical acceleration incident to maneuvers or bumps is
sufficient to fo rce the ball against the seat. Thus the fu el which is lifted to the top of the float
chamber under these conditions is prevented from passing over into the mixture control chamber
thereby causing malfunctioning.
A IR CRAFT DEVELOPMENT
SECTIONAL VIEW OF STROMBERG NA-YSD CARBURETOR (Ser v ice Tes t Model)
The mixture control which is of the back-suction type with constant suct ion and variable air­bleed
between the air intake and control chamber is the same as used on the NA-YS carburetor .
except that the control valve has a g reater range of adjustment. A new idle adjustment and quad­rant
have been incorporated in the design to provide easy adjustment when the carburetor is titted
to the engine. There are no fuel strain ers in the carburetor, and it is recommended in the installa­tion
that the lin e strainer be mounted on the engine as close to the carburetor as possible to pre­clude
the use of hose connections between the strainer and the carburetor s. The metering character­istics
of the new carburetor are almost identical with those of the standard carburetor . Adjust­ment
and synchronization of the carburetors at idling speed are also effected in the same manner as
on the standard models.
STROMBERG NA-YSD CARBURETORS ASSEMBLED WITH AIR INTAKE AND MANIFOLDS
24 T E C H N I C A L B U L L E T I N N o. 4 5
Scintilla Double Type Magneto.
A Scintilla douhle type magneto similar in general arrangement to the Splitdorf magneto is
under development. Three models of this type are on order for the E ngineering Division where
they will be subj ected to a series of SO-hour bench endurance tests at high speeds.
Breaker Mechanisms.
A study of breaker mechani sms has been initiated for three reasons; fir st. to reduce the severity
of breaker action by a change in cam contours. second , to reduce wear of breaker points thru modi­ficat
ion of the breaker action and third , to protect the breaker points from oil. New cam out­lines
have been worked out for service equipment, and a pivotless breaker is undergoing endurance
test, having completed over 500 hours of bench test at th is writing.
Splitdorf Model VA Magneto.
The Splitdorf l\ I ode I VA magneto is of the double vertical t_vpe with in tegral mounting flange
and single ,·ertical shaft rotor . It differs from conventional t_vpes of magnetos in that it has two
separate electrical and magneto circuits, two breaker mechanisms, two condensers and two coils­each
circuit being independent yet operated by a common rotor. Operation of one side of the
magneto is therefore not affected by failure of the other to functi on. In other words thi s ar­rangement
might be termed a single magneto with double wi ndings-a type of construction that
permits a substantial reduction in in stalled weight wi thout sacrifice in reliability.
In the in stallation the distributors are 1nounted separately from the magneto. The magneto
when mounted vertically in the vee of the engine requires no additional dri ve mechanism other
than that al ready provided by the engine camshaft drive. The in stall ation of the Model VA mag­neto
which weighs about 15 pounds complete with flange permits a saving in in stalled weight of
approximately 10 to 20 pounds over conventional dual magneto in stallation req uiring special mount­ing
brackets.
SPLITDORF MODEL VA MAGNETO.
(Double vertical type with single rntor.)
AIRCRAFT DEVELOPMENT 25
\ •
INDEPENDENT BREAKER MECHANISMS ON SPLITDORF VA MAGNETO.
Practically all work in connection with the development of the Splitdorf magnetos has been
concentrated on the VA type. Six tests aggregating about 300 hours have been conducted on this
type of magneto in an effort to develop it to the point where it will give sati sfactory operation over
a long period without overhaul. To accompli sh this se\•eral modifi cations of the breaker mechan­ism
have been necessary. The incorporation of these modifi cations in all magnetos of this type
has been requested of the Splitdorf Company. \t\fhen this work is completed it is believed that a
satisfactory magneto for sen ·ice use will have been obtained .
B. G. Midget Spark Plugs.
A small spark plug, approximately half the size of the present conventional type plug. is under
development for aviation engines by the B. G. Corporation. These plugs have sati sfactorily com­pleted
preliminary tests, g iving apparently a much wider range of operation than full size plugs of
simi lar design. A sufficient quantity has been ordered for further tests.
RESEARCH AND EXPERIMENT
I
RESUME OF ENGINEERING DIVISION
SERIAL REPORTS.
Serial Reports marked with an asterisk (*) will
be 1:ssu.cd by the Chief of Air Service as
"Air S ervice Inforniation Circulars."
AIRPl .. ANE SECTION
Charts for Solution of Stresses in Airplane Wing Spars. *Serial No. 2597
Ordinarily the calculation of -stresses in airplane wing spars involves the solution of the three­moment
equation by substituting different variables to accommodate the various types. About two
years ago a graphical method for determining s~ea r s and primary bending moments in spars was
evolved by Mr. Frederic F lader , a design engineer then in the employ of the E ngineering Division.
By this method, which was presented in the form of a series of charts, the mathematical processes
in the solution of the three-moment equation could be readily performed graphicall y.
Since that time a new series of charts has been prepared and presented in this report, incor­porating
the same general principles advanced by l\Ir. F lader but revised to provide for a later
method of computing load distribution over the wing tip, a change that has come about since the
original charts were completed. The new charts are based upon the new schedule for wing tip
load distribution as set forth in the 1925 Edition of the Air Service "Handbook of Instructions for
Airplane Designers," published by the Engineering Division. These charts differ from the originals
in that they are presented in nomographic form which greatly facilitates their use for the solution of
spar stresses.
Solutions obtained from these charts involve primar y shears and bending moments clue to
transverse air loads only. T heir use in practical design problems is valuable in locating the support­ing
members of the cellule in order to secure the most economical design for the spars as well as
in selecting tentative spar sizes. Every design, however , should be checked by means of a standard
method of covering the effects of combined bending and axial loads in the spars before construc­tion
is started . Such procedure will expedite structural anaysis of wings by saving time and pre­cluding
errors.
A modification of the three-moment equation to fit different cases of wing beams shows the
possibi lity of solving the equation graphi cally, by means of charts. It is believed that the eight charts
given in this report cover all cases for modern single bay airplanes as well as a maj ority of cases for
two bay airplanes.
Equations involving more than two variables such as those used for wing beams in airnlanes
having more than two bays are not susceptible to easy solution by the methods used in th ~ con­struction
of these charts.
Airplane Performance as Determined by Modern Conception of Drag. ':'Serial No. 2614
The theories advanced in this report are given as a simple and practical explanation of the mod­ern
conception of aerodynamic drag, parasite or induced, and its application in estimating power
consumption of airplanes. T his new point of view on airplane drag in performance analysis re­quires
that such established conceptions as aspect ratio, gap to chord ratio, L/ D and D / L he used
less frequently and that other new quantities such as equivalent monoplane span. span loading,
gap to span ratio, wing fri ction and other new terms be visuali zed and used concurrently.
Several charts and problems showing the application of these new conceptions are included.
RESEARCH AN D EXPE RIME NT 27
Static Test of Curtiss P-1 Wings. Serial No. 2616
This report contains an account of the static tests conducted at I\f cCook Field on a set of wings
for the Curtiss pursuit airplane . Model P -1. T11e wings withstood all tests satisfactorily, supporting
an eight per cent overload for high incidence condition.
Description and drawings of the wing structure and views of the tests are appended.
Static Test of Woven Plywood Wing Panel. Serial No. 2619
In this report will he found the results of a static test of a sample wing panel of woven plywood
construction submitted by the Forest Products Laboratory. The panel, a RAF-15 section, failed
to meet the strength requirements of a standard DH-4B wing for which it was designed.
BASKET WEAVE COVERING ON WOVEN PLYWOOD WING.
(Submitted by Forest Products Laboratory. )
The construction of this panel invites unusual interest in that it was built entirely of wood,
held together with glue. T he structure utilized two multiple spars, each composed of five plywood
"I" sections joined at the strut points by spruce blocks which were glued and pinned to the spars.
T he same type of construction was used for the ribs which were joined at their extremities by
spruce strips shaped to form the leading and trailing edges. The covering was attached to the ribs
with glue, no nails or screws being used. It consisted of a light plywood sheeting, 1/ 4 of an inch
thick, composed of two thin layers of spruce plywood separated by a sheet of corrugated spruce
veneer. the whole glued together. The surface layers were made up of narrow spruce strips inter­woven
on a special loom to give a "basket weave" a s shown in the sketch. The panel had an area
of 106.6 square feet and weighed 111 pounds less fittings and wires.
Wind Tunnel Tests.
The fo llowing reports contain aerodynamical data on various airplane models and surfaces as
determined in the wind tunnel.
Serial No. 2587-Wing F lap Test of DH-4B Airplane Model.
Serial No. 2588- 1/ 15 Scale I\fodel of Proposed Verville-Packard "1500" Geared Engine Bi­plane
Racer ( 1924) .
*Serial No. 2600--Six Horizontal Tail Surface D esigns Using USA-47 Section. Supplement
to Serial No. 2463 (A. S. 1. C. 511 ).
Serial No. 2603- Model of Engineering Division XC0-5 Observation Airplane.
EQUIPMENT SECTION.
Recommendations for Improving Model 1924 (Type A-3) Flight Indicator. Serial No. 2598
The consensus of opinion regarding the model 1924 F light Indicator (A. S. Type A-3) , as de­termined
from service test reports, especially those in which the in strument had been used in an
emergency. is that this in strument is extremely valuable in cloud or night fl ying . T here are, how-
28 T E C H N J C A L B U L L E T I N N o. 4 5
ever, some complaints due to supersensitiveness of the pitch indicator and other minor faults which
require correction during flight. The changes by which these defects may be eliminated are dis­cussed
in this report, together with sketches and views of their proposed installation.
By ·carrying out the recommendations given h erein it is believed that an ideal in strument can be
constructed that will require no adjustments during Right under any weather conditions, yet he
sensitive. reliable and easy to read.
Three-Leg Speed Course. Serial No. 2604
A three-legged speed course, described in this report, has been laid out as a simple method for
te<:>ting airships and airship instruments, in which it is necessary to eliminate the effect of wind
and to average out the irregularities of Right. The chief advantage of the method lies in the fact
that it is not necessary to select a time for flying a speed course when the wind has a negligible
velocity as required by the method of traversing a single leg course in two directions. It is also
believed that this feature may allow speed courses to be flown at higher altitudes in the interest of
safety. The method is also applicable for the same purpose in testing airplanes.
Vector diagrams for three-legged open and closed courses and a diagram of the speed course
at Scott Field are appended.
Location of Airspeed Tubes on TC Airships. Serial No. 2609
Inasmuch as the location of airspeed Pitot tubes on TC airships had never been checked with
respect to the accuracy of the indications given by the airspeed indicator, it became necessary to
explore the airstream in the vicinity of the car in order to obtain a position that would give indica­tions
as close to true airspeed as possible without introducing objectionable in stallations. The loca­tion
finally compromised upon, in which the airspeed tube is mounted well forward of the nose of
the airship car , gives indications over the working range of the instrument within one and one-half
miles per hour of the true ai rspeed. This location is recommended for adoption on all TC airships
and other similar types which employ the suspended car.
A photograph of the new location as recommended for TC air ships is appended.
FL YING SECTION
Performance Tests.
The following reports contain detailed accounts of performance tests conducted by the Army
Air Service Engi neering Division at McCook F ield.
Serial No.
Serial No.
Serial No.
Serial No.
2593-Loening Amphibian with Inverted Liberty and Three-Bladed Dural Pro­peller.
259~C urti ss P-1 (Curtiss D-12 low compression engine) with and without under­slung
Gas Tank.
2605- E lias XNBS-3 with two Liberty E ngines and Douglas vVorld Crui se pro­pellers.
(Performance summary with Hartzell propellers included).
2615-Curti ss PvV-8 with super charged Curti ss D- 12 engine and E ngineering
Division propeller.
MATERIAL SECTION
Cadmium Plating by Means of the Udylite Process. *Serial No. 2584
The l1clylite Process is a process for the electrolytic deposition of metallic cadmium on metals.
Cadmium is a relatively soft ductile metal having a specific gravity of 8.648 and a melting point of
321 ° C. In appearance it resembles si lver and aluminum, but in its chemical and physical proper­ties
it is similar to zinc. However, it does not form basic salts as readily as zinc. Cadmium lies be­tween
zinc and iron in the electromotive force series, ranking with these metals in regard to solution
pressure as fo llows: Iron--.34, Cadmium-.42 and Zinc- .77. By virtue of its position in this
series it should give theoretically a better protect ion to steel than zinc.
IvESEARCH AN D EX PERIME N T 29
Cadmium is no better than zinc from an errosion standpoint, hut it offers greater resistance to
corrosion from atmospheric and salt spray exposures, thus giving equivalent protection with a thin­ner
plate. This is very desirable in the rust-proofing of threaded parts such as streamline wire, tie
rods, nuts, bolts and other parts having close tolerances. \!Vith zinc plating which corrodes and erodes
appreciably, it is necessary to apply a greater thickness of metal. In close tolerances this requires
under-cutting of the parts. For instance on steel parts cadmium plating three ten thousandths
( .0003) of an inch in thickness may be used as an alternative for zinc plating one thousandths of
an inch ( .001) in thickness. Cadmium plating imparts a smooth, lustrous and apparently dense
fini sh which may he subsequently plated, varnished or enameled.
A complete account of the process and its application is given in this report.
POWER PLANT SECTION
Second Test of Liberty Engine with Experimental Parts. Serial No. 2529
The fir st of a series of full throttle Liberty engine tests to determine the suitability of various
experimental parts and accessories for service use was reported in Engineering Division Serial No.
2490 (Air Service Information Circular No. 423) on page 27 Technical Bulletin N o. 43. In that
test the engine was equipped with the foHowing experimental materials:
Agrilite and Kelmet bearings
Genelite and Durex gun synchronizer drive bushings
Navy stub tooth gears
Reinforced cylinders
Tulip valves. Army and Navy types
l\.Ionel coated, nickel coated and calorized valves
Standard and malleable as cast or heat-treated cast iron valve guides
Alemite generator lubricator
Rigid fuel connections
Rockwell water pump modification
Centrifugal oil cleaner
Of these parts, the gun synchronizer dri ve bushings, stub tooth gear s, reinforced cylinders,
Army tulip valves, Alemite generator lubricator , rigid fuel connections and Rockwell water pump
modifi cation warranted further trial and were subsequently rein stal'led for the second test which is
discussed in this report. Some additional parts were also in stalled for the second test such as
Allison steel-backed connecting rod bearings to reduce, if possible, the flexing of the bearing shells
with consequent cracking of the babbitt, oil groove rocker arm bearings to reduce oil leakage at
these points, Navy type reinforced cylinders, Army type silchrome tulip valves with hardened
sterns, aluminum bronze valve guides, jump-gap di stributors and B. G. lXA spark plugs.
The second test was terminated after twenty-four hours of full throttle operation by failure of
the steel-backed connecting rod bearings, clue to the loosening of the babbitt metal both on the
faces and at the fillets. The failure was ascribed to the use of unsatisfactory bearing metal and to
chilling at the fillets. The extruded aluminum bronze guides appeared to be better than the cast
bronze guides. The tulip valves after test were in much better condition than the standard valves
after similar treatment particularly those valves with hardened stems which showed definite super­iority.
It was impossible, however, to continue the test long enough to permit definite conclusions
to be drawri regarding the remainder of the experimental equipment. As a result a third test was ·
run as discussed in Engineering Division Serial No. 2613 on page 38 following .
Bearing Load Analysis of the Air-Cooled Liberty Engine. Serial No. 2549
An analysis of the principal bearing loads of the air-cooled Liberty engine disclosed that this
engine may be run satisfactorily at 1900 r. p. m. but not at 2100 r. p. m. , provided the bearing
stiffness is increased sufficiently by the use of the Navy crankshaft and steel-backed bearings. From
the standpoint of satisfactory bearing and crankshaft Ii fe it is undesirable to run this engine at a
speed exceeding 1800 r. p. m. Maximum required power may be obtained by increasing the brake
mean effective pressure. This may be attained by enlarging the capacity of the rotary induction
system.
30 T E C H N I C A L B U L L E T I N N o. 4 5
T he air-cooled Liberty engine differs from the standard Liberty water-cooled engine in the de­sign
of the cylinders, the pistons, the camshaf ts and the camshaft housings. The cylinders are of
smaller bore ( 4-5/ 8 inches) , necessitated on account of the space required between them for the
cooling fin s. The effect of reducti on in piston displacement on power is offset by a higher rotative
speed and an increased mean effective pressure as shown by dvnamometer tests. Higher operating
speed of this engine is possible because of the reduced reciprocating weights which are twenty-two
per cent less than in the standard Liberty engine.
Steel-hacked bearings are l1 secl in the air-cooled Liberty. They are of the same design as the
bronze-backed bearings used in the standard engine, but their stiffness is more than double that of
- the standard bearings clue to the use of the steel back. Ordinarily after a fifty-hour duration test,
the bronze-backed connecting rod bearings in the standard Liberty must be replaced clue to cracking
of the babbitt. At the encl of a similar test on the air-cooled Liberty, however, the condition of
the steel-backed babbitt bearings was such that an additional fif ty-hour duration test was thought
possible.
Test of Stromberg NA-812 Carburetor for Packard lA-2500 Engine. Serial No. 2548
During preliminary test work in connection with the development of the Packard l A-2500
engine, carburetor settings were used to giYe satisfactory operation at the particular speed that the
SO-hour or other test required . Reports from the Packard factory during this development incli­catecl
that carburetion was not entirely satisfactory inasmuch as smooth operation could not be ob­tained
over the propeller load range without excessive fuel consumption at full throttle. In an ef­fort
to correct this fault, several types of di scharge nozz les were used with varying success. It
therefore seemed advisable to place an engine on the dynamometer to determine a carburetor setting
that would give average horsepower and fuel consumption with smooth operation. The cletailecl
specification for this setting is given in this report.
STROMBERG NA-512 CARBURETOR FOR PACKARD IA-2500 ENGINE.
RESEARCH AN D EX PERIMENT 31
STROMBERG NA-Sl2 CARBURETOR WITH HALVES PARTED SHOWING DOUBLE JETS AND FLOAT CHAMBERS.
T he Stromberg NA-S 12 carburetor used on the Packard l A-2500 engine is of the single
barrel type. It differs from other carburetors of this type manufactured by the Stromberg :rvfotor
Devices Company of Chicago in that it is unusual 1 v large ( 3-15/ 16 inch barrel ) and is fitt ed with
two cl isc11arge nozzles and a float chamber at each side of the barrel. The two fl oat chambers are
~upplied with fuel by the fl oat needle valve and fuel inlet at the rear. The needle valve is oper­ated
by a common lever connecting the two float s in much the same manner as in the type "Y" car­buretor
s. Two separate metering systems and discharge nozzles are used in this carburetor, the
di scharge nozzles being placed on a line perpendicular to the throttle shaft and parallel to the center­line
of the engine. The rear nozzle which is on the same side of the barrel as the id le system is
supplied with fuel thru passages leading from the right float chamber , whereas the front nozzle
is supplied from the left fl oat chamber. Standard Stromberg air bleed metering system, accelerat­ing
well and idle system are empl oyed. The mixture control is of the back-suction type with vari­able
air bleed.
Several views of the carburetor and the di scharge nozzles together with considerable plotted and
tabulated data are appended.
Valve and Induction Losses of Typical Aircraft Engine Cylinders. Serial No. 2551
This test was conducted to obtain in formation on the pressure losses experienced in various
types of aircraft engine cylinders and induction systems under conditions of steady air fl ow. Some
work along this line bad already been clone by the Cla rke Thomson Research and reported by the
National Advisory Committee for i\eronautics in Report No. 24. "Air F low Tbru Poppet Valves."
This report . however, was confined to di scussing the relati ve merits of single and double valves
and comparing their coefficients of di scharge for various li fts. In order to apply this to service
engines and obtain enl ightenment on many new qu estions of design upon which there existed no
specific data fo r reference, the study was extended. It was also deemed advisable to obtain some
pertinent information upon the unusual type of va lve used in the ,.:\]men "Barrel" engine for com­parison
with the standard type of poppet valw.
Air fl ow over a wide range of valve lifts was determined by connecting the test cylinders to a
Nash "Hytor" pump and measuring the flow by means of a smooth approach orifice. Pressure loss
was measured by means of a differential manometer connected between the port and the lower part of
the cylinder. P ressure losses thru the valves only were invest igated , and in all cases, except where
the cylinders were experimental and not provided with standard rnani folds, the losses tbru both
manifolds and inlet valves were measured.
32 T E C H N I C A L B U L L E T I N N o. 4 5
The characteri stics of the yarious cylinders in vestigate<l are given in the fo llowing table :
T y pe of Bore Stroke Displ. Combustion Intake Type of Diam. Seat Lift
Cylinder (in . ) (in.) ( c u . in . ) Chamber V a lves Valve Port Angle (In.)
(in.) (deg.)
Lihertv ..... .. 5 7 137.4 Bumped 1 Mush. ) -.J~ 30 .437
Libert~ ... . ... 5 7 137.4 Bumped 1 Tulip 2.5 30 .437
W- lA . . . . ... . . 5.5 6.5 154.4 Roof 2 T ulip 1.75 30 .375
W (2-valve) . . 5.5 6.5 154.4 Roof 1 Tulip 2.625 30 .6
w (A l. head) . 5.5 6.5 154.4 Roof 2 Tulip 1.75 30 .375
\V (A l. head) . 5.5 6.5 154.4 Roof 1 T ulip 1.75 30 .375
Almen A-3 .... 4.125 5.5 73.5 Modi. hemisphere P late P late
J (air-cooled) .. 5.625 6.5 161.5 Hemisphere 1 T ulip 2.5 45 .562
J (air-cooled) .. 5.625 6.5 161.5 Hemisphere 1 Lib. Tulip 2.5 30 .562
J (air-cooled) . . 5.625 6.5 161.5 Hemisphere 1 Lib. Mush. 2.5 30 .562
D-12 (Curtiss). 4.5 6.0 95.4 Flat 2 Tulip 1.531 45 .398
The fundamental relations obtained in this investigation were determined for air flow against
pressure loss for various valve lifts. All of these data have not been analyzed but they are pre­sen
ted in graphical form with typical methods for analysis which are given to show the various
ways in which this in fo rmation may be used for improvement of design.
In general the following conclusions were drawn:
1. That the coefficient of discharge of poppet val ves decreases as Ii ft 1s increased but re­mames
practically constant for all air fl ow at a given lift;
2. That, for a given lift, the loss thru the va lve varies as a constant power of the air flow ;
3. That losses thru mani fold and carburetor fo r a given air flow at full throttle are indepen­dent
of valve lift;
4. That in a given cylinder the maximum diameter single valve is more efficient per inch of
perimeter than double valves of maximum diameter, due to the greater interference of double
Yalves with the cylinder walls and with each other.
5. That high performance of 4-valve cylinders is accounted for by the inherentl y greater
valve perimeter obtainable with 4-valve cylinders, which more than offsets the inefficiency of double
Yalve construction.
6. That interference with double valves is greater between the cylinder walls and the valves
than between the valves themselves.
7. In the Liberty cylinder and in the T ype J air-cooled cylinder, which are typical of the re­spective
bumped and spherical types of combustion chambers, tulip ,·alves proved less efficient than
mush room valves.
8. In the Liberty engine, it was ascertain ed that manifold and carburetor losses in the first ,
third . fourth and sixth cylinder positions are slightly higher than in the second and fifth cylinder
positions.
9. Losses thru the Almen A-3 valve and manifold were found to be excessively high during
the first 90 degrees of crankshaft travel, indicating a necessary redesign of the port and a change in
the valve timing.
10. In the Model Vl -lA engine with the four-valve cylinder, the loss thru the carburetor.
manifold and valves for any given air fl ow is practically constant for valve li fts above four tenths
of an inch.
11. T hat cast inlet ports of the \V- lA aluminum cylinder head a re more effi cient at high air
flow than the built-up ports of the \V-lA steel head cylinder.
Standard and Katalite-Coated Liberty Cylinders. Serial No. 2553
Katalite is a dull red paint-like coating manufactured by the American Katalite Corporation,
Brooklyn, N. Y ., for application to the cylinder and piston head of an internal combustion engine to
reduce fuel consumption and in some measure decrease the tendency for detonation. The sub­stance
apparently bakes upon the surfaces that come in contact with combustible gases. Its action
is claimed to be a catalytic, assisting combustion merely by its presence. The chief claims of its
producers that thi s substance reduces fu el consumption and also that ( to quote) '-'the maximum
power point with Katalite is practically identical with the point of optimum fuel economy, which of
course simplifies greatly the problem of carburetion ," could not be substantiated.
5CCT101Y A ".A.
lJIRtl /IYLCT flJR?S
,EJ'PERINC!YTl?L Z-YRLl'C JY-C>l./ltOER
5ECTIOl'f .A_ _.\.
OF /IYLET
RE SE ARC H AN D EXP ERI M E N T
TYPE .)"R!R Cttr"EJ7 CYLl/YPER
RL .NC/Y H-.7 C/Y6/IYE
srcfl lt'f//t? 4 -J111LJE w-111c>Vh/JfR
SECTA'.#'Y A A CF //'/LET A?RJY
LIBERTY CYL llYll"R
SECTIOl>' A -A
OFIJYLeT
VALVE ARRANGEMENTS OF CYLINDERS USED IN STUDY OF INDUCTION LOSSES IN AIRCRAFT ENGINES.
33
.34 TECH~TICAL BULLETIN No. 45
First 50-Hour Test of Air-Cooled Liberty Engine. *Serial No. 2555
This test was made to demonstrate the feasibility of cooling high power ai r -cooled cylinders
in the narrow vee in-line arrangement as typified in the air-cooled Liberty engine developed by the
Engineering Division. T he success of this project has opened a large field for the application of
large air-cooled vee type engines to ai rcraft, particularly commercial aircraft.
The air-cooled Liberty engine is a modification of the standard Liberty engine whereby the
water-cooled cylinders have been replaced by air-cooled cylinders and other new parts. The modi­fi
cations include an 'air-cooled cylinder of smaller bore than the standard cylinder to accommodate
the fins, a new piston of 4-5/ 8 inches in diameter, a new piston pin, a new bushing for the small
encl of the connecting rod, an overhead camshaft and housing and a suitable cowling to direct the
propeller blast into the vee where it cools the cylinders in escaping between the fins.
The cylinder construction is a modification of the Type "J" cylinder, an Engineeri ng Division
development which forms the basis of all successful large size air-cooled cylinders in this country.
The air-cooled Liberty cylinder consists of an aluminum hea'cl, screwed and shrunk into place. The
exhaust valves are salt-cooled, and the exhaust side of the cylinder is placed on the inside of the
vee in order to bring the coolest air over the hottest part of the cylinder head. Additional modifi­cations
of the standard engine include steel-backed bearings in the connecting rods, omission of the
water pump and the replacement of the oil pump by a unit of greater volume such as used on the
Navy epicylic geared Liberty. Either conventional carburetor or rotary induction may be used.
The report gives the log of the first SO-hour endurance test including several views of the en­gine,
cylinder construction and other graphical data.
Endurance Test of Packard lA-1500 Engine with Slipper Type Pistons,
Steel-Backed Bearings and Salt-Cooled Valves. Serial No. 2576
T his report contain s an account of an endurance test of a Packard l A-1500 engine equipped
with light weight slipper type pistons, Allison steel-hacked main and connecting rod bearings, and
salt-cooled exhaust valves. The engine performed unsatisfactory at the speed and power maintained
during this test and was returned to the Packard Company for rebuilding in accordance with the
latest design changes. A second endurance test of the rebuilt engine incorporating the above parts
was recommended.
Test of Viking Type Fuel Pump Made by Wright Aeronautical
Corporation. Serial No. 2577
A Viking type fuel pump, Serial No. 348. made and submitted hy the ·wright Aeronautical
Corporation, was tested by the E ngineering Division to determine the fo llowing characteri stics:
1. Capacity at various speeds and discharge pressures;
2. Ability of pump to prime wet or dry;
3. Ability of pump to run dry.
The test showed that the capacity of the pump is ample for the purpose designed at speeds
above 500 r. p. m., but that it is not satisfactory at idling speeds. The pump will not prime dry.
and wet priming is accomplished only at very small li ft heads and at very high speeds because of
large clearances. The pump passed the dry tests satis factorily.
Views of the pumps are appended.
Test of Zenith E. D. 52 Carburetors on Curtiss D-12 Engine. Serial No. 2599
The Stromberg NA-YS or NA-YSA carburetor as now used as standard equipment on the
Curtiss D-12 engine is not suitab1e for use with the side type supercharger. To incorporate the
necessary modifications in this type of carburetor to render it suitable for use with the side type
supercharger would necessitate practically a complete redesign without much assurance of satis­factory
performance. It was therefore decided to determine the desirability of using E ngineering
Division l\fodel 5~ (Zenith) carburetor s, which are specially designed for use with superchargers,
on this engine.
RESE A RCH AND EXPERIMENT 35
It was found that the Zenith E. D. 52 carburetors on the Curtiss D-12 engine functioned sati s­factorily
on 'the dynarnorneter but not in flight. The operation of the engine in the Curtiss pursuit
airplane provecl un sati sfactory during take-off and in maneuvers with the result that these car­buretors
were not recommended for use on the Curtiss D-12 engine.
A description of the E. D. 52 carburetor will be found on the following page.
Bearing Load Analysis of Modified Curtiss D-12 Engine
Operating at 2800 r. p. m. Serial No. 2601
For the purpose of investigating problems and bearing loads encountered in high speed opera­tion
of modern aircraft engines, the Engineering Division conducted an endurance test on a modi­fied
Curtiss D-12 engine operating at 2800 revolutions per minute.
Preparatory to the test, the engine was fitted with steel-backed bearings, standard pistons
with shortened skirt, and special Curtiss V-1400 articulated type connecting rods with special roe!
pins and bolts-all modifications having been made by the Curtiss Aeroplane & Motor Company.
Jn this engine the crankpin bearing of the special connecting rod is babbitted directly on the steel
of the rod whereas, the main crankshaft bearings have steel shells, with their inner surfaces
turned and tinned immediately after machining. The babbitt which forms the bearing surface is
applied after tinning.
The use of steel-backed main and connecting rod bearings is in accordance with recent practice
in aircraft engine design, which has proven sati sfactory in prolonged laboratory tests. In speeding
up the aircraft engine, the design of the bearings involves one of the major problems since the
hearing loads and rubbing factors are greatly increased, clue to the higher rotational speed imposed
upon. the bearings.
In the present investigation an analysis is made of the bearing loads and rubbing factors
which occur in operating the modified Curtiss D-12 engine at a speed of 2800 r. p. m. , and the
values obtained are compared with corresponding values for the Packard l A-1500 and air-cooled
Liberty engines in which the types of bearings are analogous.
Development and Test of Stromberg NA-Y5D Carburetor
For Curtiss D-12 Engine. Serial No. 2602
Shortly after the delivery of the first PW-8 airplanes to the service, it was found that the
Stromberg N A-Y 5 carburetors with which these airplanes were equipped did not function sati s­factorily
on the Curtiss D-12 engine when used in fast pursuit aircraft. The most serious fault
with these carburetors was their tendency to cause the engine to cut-out when the airplane was tak­ing
off or when the airplane was suddenly nosed over into a dive from either a climbing or a level
flight position. The Engineering Division immediately attempted to eliminate the defects inherent
in these carburetors. First, the standard carburetor was modified , but repeated failures of the mod1-
fications to correct the difficulty soon led to the development of a new carburetor in cooperation with
the Stromberg Motor Devices Company.
Views and description of the new NA-Y5D carburetor are given in the report.
Test of Stromberg NA-U6A Carburetors on Wright "H" Engine. Serial No. 2606
The test was conducted for the purpose of checking the performance of the production type
NA-U6A carburetors on the \ i\Tright "H" engine, particularly the automatic mixture control which
constitutes the chief feature of interest on this carburetor. This unit fulfills the need for an auto­matic
mixture control by maintaining a constant mixture ratio for the engine,,at all altitudes, thus
relieving the pilot of the necessity of adjusting the mixture to compensate for changes in altitude.
With this device it is possible for the pilot after setting the mixture control lever in the cockpit in
the automatic control position to fly to any altitude up to and including 20.000 feet without chang­ing
the mixture control lever. In case of accident to the automatic control unit or iri event the
pilot desires to lean or enrich the mixture for other reasons, he may operate the mixture control
lever in the usual manner without interference. The automatic control is built as a removable unit
in order that it may be adjusted in service without disturbing the carburetor installation and that
it may be adapted to other carburetors.**
**This same type of automatic mixture control unit is being developed for use with Stromberg NA-Y5D carburetors
on the Curtiss D-1 2 engine ..
•
36 T E C FI N I C f\ L B U L L E T I N N o. 4 5
The Stromberg NA-U6A carburetor, several \·iews of which are included in the report, was
designed and built by the Stromberg Motor Devices Company in cooperation with the E ngineering
Division for use on the \!\f right Model H engine. This carburetor is of the double barrel type with
the float chamber between the barrels. Metering is accompli shed by the conventional Stromberg air ­bleed
system. T he chief difference between this carburetor and the Stromberg NA-U6 model is
in the kind of mixture control which is of the back suction type. \i\Tith this type of control, the
fl oat chamber is vented to the venturi s and conn ected to the air intake thru a valve which regulates
the pressure in the float chamber.
Cylinder and Manifold Pressures During Induction and Exhaust Strokes. Serial No. 2608
The data incorporated in this report were obtained during an in vestigation of induction losses
in the Packard l A-1237 engine and applied as reported in Seri al No. 2483 "Performance of P ack­arcl
l A-1237 E ngine with Niodified Intake Manifolds and Camshaf ts" (see page 26, T echnical B ul­lctin
No. 43) . T he pressures in the cylinder and in the inlet manifold were measured to show the
effects of changing the manifold arrangement and camshaft design on the P ackard engine, but it is
believed that these pressure studies are applicable to other engines as well.
The pressure studies are presented from two standpoints; fir st, to show the actual pressures
in the induction system and in the cylinder and second , to point out how these pressures are affected
by different types of mani fo lds and variations in intake va lve timing . T11e pressure drop thru
the intake valve affords a means of estimating the rate of flow into the cylinder at various points
in the suction stroke and also a means of indicati ng whether or not the valve timing is correct for
that particular engin e.
Development and Test of Zenith ED-52 Carburetor for Liberty Engine. Serial No. 2610
In the search for a carburetor suitable for the supercharged Liberty engine, it was found that
the present Zenith US-52 carburetor now standard for this engine could not be made to incorpor­ate
the desired features. Accordingly a new carburetor was developed , the model ED-52, in which
certain desirable fea tures of the standard Zenith carburetor were retained .
ZENITH ED-52 CARBURETOR FOR SUPERCHARGED LIBERTY ENGINE.
RESEARCH AND EXPERIMENT 37
The first ED-52 carburetors were designed and built by the Engineering Division for develop­mental
purposes. U pon completion of the experimental work, an improved design was presented
to the Zenith-Detroit Corporation for production purposes. The production model carburetors
1nanufacturecl by this firm were designated as Zenith ED-52.
In the ED-52 carburetor, the venturi, the main metering jet, the compensating metering jet
and the compensator discharge nozzles are interchangeable with the standard Zenith US-52 car­buretor.
The metering system is also the same as in the standard Zenith carburetor with the ex­ception
of the idle well and fl.oat chatnber which are vented directly into the air intake. The com­pensator
jets and main discharge nozzles are feel by separate fuel passages from the fl.oat chamber.
The mixture control is of the orifice plate type, the plate being placed in the bottom of the float
chamber and operated by means of a vertical shaft and gears fitted in the upper half of the car­buretor.
There are two rows of metering orifices in the plate so arranged that one orifice from each
row coincides with a vertical fuel passage leading to the main metering jet which in this case acts
only as a discharge nozzle. Three mixture control positions are provided which give adequate
range for use with a supercharger. A hinged type of float mechanism is used, and the needle
1·alves (Stromberg type) are interchangeable with those of the Stromberg NA-LS carburetor. In
the lower half of the casting around the float needle valve a strainer is provided. This may be
removed for cleaning by removing the strainer plug. The air intake flange is of sufficient width
and strength to accommodate the supercharger air duct. Packing glands are provided around the
throttle shafts to prevent leakage of the fuel-air mixture during supercharger operation.
The report giYes a discussion of the metering characteristics of the ED-52 carburetor as ob­tained
on the dynamorneter and the test data including fuel consumption as obtained in flight rather
than a detailed history of its development. 'It states that the Zenith ED-52 carburetor is satisfac-
ZENITH ED-52 CARBURETOR WITH HALVES PARTED.
33 T E C H N I C A L B U L L E T I N N o. 4 5
tory fo r service use ancl recommends its use with supercharger s. Altho the new carburetor is a
definite improvement over the standard Zenith U S-52, the di fference in general operation is not
sufficient to warrant a change in the standard carburetor ef]uipm ent for the Liberty "1 2" engine.
Third Endurance 'fest of Liberty Engine
with Experimental Parts. Serial No. 2613
T his report gives an account of the third of a series of fi ft y-hour full throttle endurance tests
of the Liberty engine as equipped with various modifications and experimental parts.
T he fir st test (see Air Service In fo rmation Circular No. 423) resulted in the rej ection of
Kelmet and Agrilite bea rings, coated valves and pi stons. and malleable cast iron valve guides. Oilless
gun synchroni zer dr ive bushings, stub tooth gears, reinforced cylinders, tulip val ves, Alemite gene­rator
lubricator. rigid fuel connections, Rockwell water pump modification and centrifugal oil
cleaner . all of which survi vecl the test, were reinstall ed in a high compression engine for the second
test as discussed in the aforegoing E ngineering D1vision Serial No. 2529 on page 29.
T he second test in volved the following parts in addition to those mentioned above : Allison steel­backed
connecting rod bearings, oil groove rocker arm bearings, silchrome tuli p val ves with hard­ened
stems, aluminum bronze valve guides. jump-gap di stributors and B. G. 1 XA spark plugs. The
results of this test which was terminated after twenty-hours running by fa ilure of the steel-backed
babbitt bearings, indicated the superiority of heat treated aluminum bronze as valve guide materiai
over cast or extruded aluminum bronze without heat t r ~atm ent , and the superiority of hardened sil ­chrome
val ves over unhardened vah·es T he test also pointed out the necessity of using different
bearing material in the steel-backed bearings and di sclosed detonation troubles attributed to the
use of rein fo rced cylinder s.
T he third test was conducted wi th the following materials. as di scussed in th is report:
Steel-backed bearings with standard babbitt lining
Rein fo rced cylinders, McCook Field type without internal water pipe
Silchrome tuli p valves with hardened stems
Magnesium piston pin bushings
Genelite and Durex oilless gun synchroni zer drive bushings
l\fodifi ed oil grooves in rocker arm bearings
Stub tooth gears
Rockwell water pump
Rigid fu el connections
Centrifugal oil cleaner on A. S. T ype A-1 oii pump
Jump-gap di stributors
Alemite lubrication of generator.
In this test there were no forced stops attributable to failure of experimental materials. The
_i\ llison steel-backed bearings passed the tests satisfactorily with the exception of a loosening of the
babbitt at the fill ets. Only one water jacket leak developed. T he silchrome tulip exhaust valves
performed satisfactorily in general , the condition of the valves with sterns run in standard cast iron
guides being definitely better than those with stems nm in guides of extruded aluminum bronze.
Some of the magnesium pi ston pin bushings had shrunk and turned in the rods but the surfaces
of the bushings we1·e found in excellent condition at the encl of the run The oil\ess gun syn­chroni
zer drive bushings proved satisfactory. but that no advantages accrued the use of oil grooves
in the rocker arm bearings. The stub tooth gears were in excellent condition except for the crank­shaft
gear which showed wear. T hese ge::n-s together with the modified water pump and the
rigid fu el connections which showed no signs of leakage during the test had completed a total of 124
hours of endurance testing. The per formance of the oil cleaner in the Stryker oil pump was un­sati
sfactory in contrast with that of the jump-gap di stributors which proved highly sati sfactory.
Lubrication of the generator hy the Alemite fittin g- was apparently adequate. At the end of the
tegt, however, the grea e wa fmmd ta have worked tlmm€tf1 t [1e 6aU (Jea r lng to t he crankcase. feav­ing
the tachometer drive gears nearly dry.
Detailed descriptions of the various experimental parts and views of their condition at the
end of the test are given.
RESEARCH AND EXPER IME NT 39
INVESTIGATION OF MATERIALS
Effect of Ag'ing on Elasticity of Aluminum Alloys.
The effect of aging on the elastic properties of aluminum alloys is under observation . Speci­mens
of duralumin of different gages taken from old material in stores or salvaged from static
tests and from various types of airplanes in the McCook Field museum have been placed on labora­tory
test. Additional data will also be obtained on the effect of aging on the tensile and bending
properties of aluminum alloys. The test samples represent .material manufactured in Germany,
France and United States. -
Hardness of Piston Alloys at Elevated Temperatures.
A report has just been completed by the Engineering Division covering an investigation of
BrinelJ hardness on piston alloys at elevated temperatures. It shows that the aluminum-nickel-mag­nesium
alloy has a greater Brine]] hardness than the copper-iron-magnesium alloy. The former is
a modification of an alloy known as Magnalite which was developed in this country several years ago,
and the latter is an alloy knOWll as No. 122 developed by the Aluminum Company of America. As
a result the nickel-bearing alloy has been selected for piston and cylinder heads of air-cooled en­gines
which operate at higher temperatures than conventional water- cooled types. Both alloys are
now being produced by the Aluminum Company of America.
Correlation of Rockwell, Scleroscope and Brinell Hardness.
As a result of a large number of tests a table has been prepared showing the correlation of
Rockwell, scleroscope and Brinell hardness numbers for several alloy steels as quenched and drawn
at temperatures from 400° to 1200° Fahrenheit. This in formation has been prepared for the use
of in spectors and designer s. The table given below is al so of use in calculating ten sile strength
owing to the very close relationsliip between tensile strength and Brine!! hardness as indicated by
the equation :
Tensile Strength = Brinell hardness X 500.
ROCKWELL-SCLEROSCOPE-BRINELL RELATIONS.
Rockwe ll I Scleroscope I Rockwell I Scleroscope · I Rockwell Diamond Brinell Diamond Brinell Diamond I Scleroscope I Brin ell
Point Point Poin t
I I I I
1 I 158 22 35 I 235 43 57 I 408
2 II 160 23 36 I 241 44 58 419
3 I 162 24 36 I 247 45 59 430
4 I 165 25 37 i 253 46 61 442
5 168 26 38 I 259 47 62 -153
6 I 171 27 39 I 265 48 63 464
7 I 174 28 40 II 272 49 65 476
8 28 I 177 29 41 I 279 50 66 488
9 29 I 180 30 42 I 286 51 67 500
10 29 183 31 43 I 294 52 69 512
11 29 ! 186 32 44 I 301 53 70 524
12 29 I 190 33 45 I 309 54 71 536
13 30 193 34 46 I 318 55 73 548
14 30
_II
197 35 47 327 56 74 561
15 30 201 36 48 337 57 76 574
16 31 i 206 37 50 347 58 77 587
17 32 I 210 38 51 357 59 78 600
18 32 I 215 39 52 367 60 80 613
19 33 I 220 40 53 377 61 81 627
20 33 II 225 41 54 387 62 82
21 34 I 230 42 56 398 63 84
i
NEW BOOKS AND DOCUMENTS
ADDITIONS TO
ENGINEERING DIVISION TECHNICAL FILES
DURING FOURTH QUARTER, 1925
INTERNATIONAL AERONAUTICS
Document numbers rifer to Engineering Division file reference
International
Propaganda and popularization. In French.
International Air Congress, Belgium. 1925.
6 P.
Sug f.~ estions for popularizing civil avia­tion.
International Air Congress. Belgium.
fi p .
Some aspect~ of commercial aviation in­surance.
Internationa l Air Congress, Bel-
1<ium. 192 5. 5 p.
Internation:! l custom house regulations.
In French. International Air Congress, Bel­J>;
ium. 1925. 3 p.
Repo!"t on Internat ional European Aero­nautic
Conference in Stockholm, Sept. 28 -30,
1925. 5 P.
Rule of aviation in t he organization of
medical field service. In French. Interna­tional
Air Congress, Belg ium. 1295. 3 p.
Ry A . 'fi lmant.
Sanitary av iation; by Angelo di Nola. In
French. International Air ~ Congress, Bel-g
ium. 192 5. 10 p.
Appointment of international commiss ion
for us ing esperan to; by Rollet de L'Isle. In
French. In ternational AiJ· Congress, Ilel ­J.{
ium. 1925. 2 p.
United States.
McCook Field accomplis hments of past
year (1924). Aviation Progress . Nov. 1,
1925. 4 p. By John F . Curry.
Flight tes ting at McCook Field. Cat.
Dec., 1925. 11 p.
Engineering Divis ion's assistance to Air
Ma il Service; by Donald L. Bruner. Oct.
25, 1925. 6 p.
Statement of activ itie3 perfo1·med by En­gineering
Division which direct ly and in­directly
aided t he United States Air Mail
Service. Sept. 23, 1925. 3 P.
Ins u lar possession : Phi lippines, Porto
Rico, Hawaii, Guam, Samoa, Virgin Islands.
Cuba, and Panama Canal. Publications for
sale by Superintendent of Documents. Ed.
1 2. Aug., 1925.
New publications of the Bureau of Stand­ards.
Sept. 3 0, 1 925.
Trend of aeronautical development. By
Hobert L. Wilson. Cat. Dec., 1925. 6 p .
Sky- writing; by Wendall H. Brookley. A
des cription of m ethod used. Cat. Oct.,
19·~5. 4 P.
Crop cens us taking by airplane. McCook
Field . July 2 9, 1925. 2 P.
Great Britain.
Visit to Royal Aircr::ift Establishment at
Farnboro. England. Sept. 4, 1925. 4 p.
Report on vi s it to Martles ham H eath.
Eng land. Aug. 28, !U,25. 4 p.
Al0.01 /5 1
Al0.01 / 49
A00.4 /7
A00.5 /32
D00.12 /227
D40 / 1
B60 /11
AOO /56
·Aoo ;:;7
DOO.ll/161
Dl3.46/67
Doo 1.12
Cl3 /92
A48.2 /119
1925-Sept.
D52.l /17 1
D52.2 /13
D52.2 /12
F35/125
F35;124
Inspection of the aviation plant of the
Hawker Engineering Company. England.
Aug. 13, 1925. 2 p.
Vis it to works of S. Smnth & Sons, Ltd.,
and description of their e lectric gyro turn­ing
·indicator. England. Sept. 17, 1925.
11 p. Illus
Report on visit to t he superm a rine works.
England. Aug. 26, 1925. 3 P.
France.
Organization of French naval aeronau ­tics.
- From parliamentary docume nts of t he
Chamber of Depu ties. In French. France.
Nov. 24, 1925. Large document.
Regu lations governing manufacture and
acceptance of commercial airp la nes. In
Fren ch. Internationa l Air Congress, Bel­gium
. 1925. 6 p .
Italy.
Italy's aeronautica l budget for 1925-26.
Tr. fromL'Air. Oct. 15, 1925. 1 P .
Review of aeronautics throughout the
world. In Italian. Rivista Aeronautica
No. 1. July, 1925. 227 illus.
Review of aeronautics throughout the
world. Supplement on aerofoi ls. In Italian .
Notiziario 'fecnico N o. 2. Aug., 1925. 139
p . Illus
Review of aeronautics throughout the
world. In Ita lian . Notiziario Tecnico No.
3 - 4. Sept., Oct., 1925. 17fi p. Illus .
Belgium.
Propaganda p rogram in favor of develop­ing
aeronautics in Belgium. In Frent· h. In­ternational
Air Congress, Belgium. 1 !J25.
6 ~ .
Cata log from John Cockerill steel factory,
Liege, Belgium. In French. Cat. Nov.,
1925. 58 p. Illus.
Air s urveying. International Air Con-gr
e~ s. Belgium. 1 925. (i p.
Competitions, Personnel, Etc.
Aeronautica l propaganda in the official
French expos itions. In French . Interna­tional
Air Congress, Belgium . 1925. 4 p.
Booklet illustrating lig ht airplanes and
engines exhibited at the Munich Traffic Ex­position.
1925. 55 p. Illus.
Req uirem e nts for entering "Cup of the
sea" and "Cup of Italy" races for sea­planes
and landplanes. Ita ly. Sept. 26,
1925. 2 p. Maps.
Program for Jacques Schneider Interna­tional
Seaplane Races. Oct. 24, 1925. 49 p.
Illus.
Official world and American a ir records.
Federation Aeronautiq ue Internationale. Dec.
l , 1925. 8 p .
F35/122
D l 3.3 /7
Turr. ­lndicators
C00/3fi
B00.6 /10
A00.3 /62
D00.12 /226
1925-July
D00.12 /223
1925- A.ug.
'DOQ.12/223
1925-Sept.
Al 0/7
Belghnn
F35/126
D62 .4/3 1
A00.7 /21
D5:~.1 /63
Misc. Germ_
D52.03 /VO
D52.03 /Dl
C7 1.61 /G9
NEW BOOKS AND DOCUMENTS
Report on worlds ' duration and dis tance
record establis h ed Aug. 7-8, 192 5. Etampes,
France. 1925. 2 P.
List of new world records recognized by
the Federation Internationale Ae ronauti;que.
N~tional Aeronautic Association. BuUetin
No. 70. Sept. 22, 19 25 . 1 p .
List o! new world records for airplanes
and seaplanes, recognized by the Federation
Aeronautic Internationa le. N a tional A ero­nautic
Association. Bulletin No. 71. Nov.
2. 1925. 2 p.
New American r ecords for airplanes and
seaplanes. National Aeronautic Association.
Bulletin No. 72. Nov. 3, 1925. 3 P .
New world records recognized by the
F. A. 1. National Aeronautic Association.
Bulletin No. 73. Nov. 11, 1925. 2 p.
Bul1etin of Federation Aeronautique Inter­nationale
for June, 1925.
Tes ting the attention and aptitude f or
piloting; by V. G .. Brabant. Kraeplin tests
for aerial navigators. In Fren ch. Interna ­tiona
l Air Congress , Belgium. 1925. 4 p.
Charts .
Two periods of fl yer's sick ness; by Georges
Ferry. "The fl yer's h eart." In French. In­terna
t iona l Air Congress, B e lg ium. 19 25.
3 p.
Psycho-physiological tests for examining
the fitness of men for aviation; by J. Beyne.
In French. International Air Congress, Bel -
g ium. 1 !:125. 2 p .
Arterial s tress in fly ers; by Victor C.
Anastas iu. In French. International Air
Congress, Belgium. 1925. 2 p.
Effect of changes in atmospheric tempera­ture
on artery pres$ure and sickness offtyers;
by Rene Cruch et. In French. International
Air Congress, Belgium. 1 925. 3 p.
Physio logical bases governing oxygen ap­paratus
used in aviation; by J. Beyne. In
French. Inte rnation a l Air Con g re s ~. Bel­g
ium. 19 25. 3 p .
Stable nervous con tro l in relation of flying
e f f iciency; by Martin Flack. International
Air Congress, Belg ium . 1925. 9 p. Chart,
diag_
Methods of estimating the night vision of
flyers . In French. By J. Beyne. Interna­t
ional Air Congress, Belg ium. 1925 . 2 p .
AERIAL NAVIGATION.
Navigation of aircraft. Navy Dept., Bu-reau
of Aeronautics. Technical n ote No.
154. Sept. 3, 1925. 39 p . Charts.
Contents:
Pt. 1. T ec hnical account of flig ht from
to Rio de J eneiro m ade by Ad­miral
Gage Coutinho and Comdr.
Sacadura Cabral, Mar. 30, to
June 1 7, 1922.
Pt. 2. Practical navigation of a ircraft ;
by Capt. F. Tymms.
Pt. :L Aerial navigation; by Comdr.
John Roger s.
Report on third international congress on
aeria l navigation h eld a t Brussels . Belgian .
Oct. 15. 1925. 3 p.
Report on third international congress for
aerial nav igation held in Brussels. England.
Oct. 19, 1925. 3 p.
Navigation by a irc r a ft in the Belgium
Congo. In French. Inte rnatio nal Air Con­gress,
Belg ium. 1 D25. 15 p.
Cla ss ification registe rs and aerial naviga-t
ion. ln French. In ternational Air Con-gress.
Belgium. 1925. 1 p.
Some medical aspects of a.ir transport;
by C. B. Heald. In tern ational Air Congress.
Belg ium. 1295. 17 p.
H ygiene in a ir traffic; by H. Ru lot. In
French. Internationa l Air Con gress, Bel-g
ium. 1925. 1 p.
Some impressio n s of the flight from Paris
to Dakar; by Capt. Arrachart. In French.
Cat. Nov., 1925. 16 P.
Night illumination for aerial navigation;
by A. Fauconnier. In French. Interna ­tional
Air Congress, Be lg ium. 1925. 12 p.
Diags.
D52.l /4 0
Farman
C7 1.tH /55
C71.61 /66
C71.61 /67
C71.61 /68
DOO. U I l '18
192 5-June
BOl. 5/4
B(i3/7
BOl.5/3
R63 /9
B63/8
Dll.33 1 /2 1
BOl.5 /2
BOl.5 /5
A40.3 /32
Doo.12 /23o
D00.1 2/229
A40.3 /34
D52.!7 /3
B0!.5/4
B60 /10
C7!.6 /84
D13.46/68
Na·1iga tion during fog, and radiogoni­metry.
French . Intern ational Air Congress,
Belgium. 1925. 6 p.
Cooch aerial navigation apparatus. In-ternational
Air Congress, Belgium. Report
No. 402. 19 25. 3 p. Diag.
Various causes of accide nts during fligh t .
Mean s to avoid t hem. In French; by Georges
Ferry. Intern ational Air Congress. Belgium.
1~25. 3 p .
Meteorology.
Meteorological protection of air lines; by
Albert Dorlodot. In French. Inter national
Air Congress, Belgium. 1925. 2 P.
Numerical index of meteorological condi­tions
on an airdrome or on an air route for
comparison with flying statistics; by G. Gold.
Intern a tiona l Air Cong r ess, Belgium. Report
No. 420. 1925. 7 p.
Wind factor in flight ; an analysis of one
year's record of the air mail. lnternationa 1
Air Congress, Belgium. 192 5. 20 p. Charts.
Winds of Oklahoma and east T exas . In-t
e rnational Air Congress , Belgium. 1925 .
8 p . Diags.
Frequency of winds of differe n t speeds at
flying levels between New York and Chicago:
by ,J. P. Van Zandt a nd Willis Ray Gregg.
A further a nalysis of the records of the Air
Mail S ervice. International Air Congress.
Belgium. 1925. 6 p . Charts.
Tables and da ta on standard atmosphere;
by Walter S. Diehl. National Advisory
Committee for Aeronautics . 1925. 28 p.
One case of supersaturation of the at­mosphere
verified by airplane; by .T. J au­motte.
In :F'rench. Internationa l Air Con­g
r ess, Belg ium . 1925. ,4 p.
Regulation.
Organization of international aeronautical
legislation. In F'rench . International Air
Congress, Be lg ium. 1 9 2 5. 3 p .
Status of present laws governing avia­tion;
by M. Thieffry. In Fre nch. Inter­national
Air Congress, Belgium. 1925. 6 p.
Suggestions concerning international regu­lations
of air routes . In French. Interna­tional
Air Congress, Belg ium. 1925. 4 p .
Ins pect ion of civ il a ircraft. Inte rnationa l
Air Congress, Belgium. 1925. 21 P.
Prevention of accidents in commercial
aviation; Ly Frerlerick Hadley P age. Inter­n
a tional Air Congress, Belgiu1n. t 925. 4 p.
INSTRUCTION
S y llabus .for training of n aval aviators
a n<l naval a viation pilois. Airpla ne. 1924.
30 p. Chart.
Roya l Air Force ftving training . P art III.
Seaplane flying . Air Minis try. Ed. 1.
June, 1925. .103 p. Illu s .
Annua l report of the Air Service Engineer­ing
School. McCook Fie ld, for year ending
Aug. 14, 1925. 9 p.
Emplovment of combined air force. Air
S e rvice T actical Sc hool. 1 924 -2 5. 41 p .
RESEARCH.
R eport of the Aeronautical ResE:arch Com­mittee
for the year ln24-25. 44 p .
Work of t he aeronautique departm ent at
the natio na l physical laboratory. Interna­tional
Air Congress, Belgium. 1925. 5 p.
Aerodynamic research. In E'rench. In-ternational
Air Congress, Belg ium. 1925.
11 p. Charts .
Experimental r esear ch in aerodynamics.
In French. Bulletin Technique No. 28.
Aug. , 1925. 44 p. Charts, diags.
Aerody na mics ; by J . Joukowski. Tr. from
Bas es Theoriques de L' Aeronautique, 1916,
by J. F. Va nier. Technical Data Sect ion,
McCook Field. Oc t. 9, 1925. 216 p.
Law of dynamic s imilitude. In French.
Internationa l Air Congress, Belgium. 1925.
10 p.
41
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42 T E C H N I C A L B U L L E T I N N o. 4 5
Principle of bird fligh t. In French. In -
ternational Air Congress, Belg ium. 1925 .
8 p. Illu s., d iags.
Theory of flapping flig hts; by Alexander
Lippisc h ; Tr. from Flugsport, June 1 7, 1925.
National Advisory Committee for Aeronau­tics.
Technical m emorandum No. 3 3 4. Oct.,
1925. 11 p, Diags,
Model drog ue experiments . Ad·visory Com­mittee
for A e ronautics. Apr., 1 9 1 8. 12 p
Diags.
Aerolog ica] soundings and the theory o f
Rjerknes cyc lones. In French. Internationa l
Air Congress, Belgium. 1925 . 5 p. Charts.
Data o n r epeated s hock tests. In French.
International Air Congress, Be lg ium. 1925.
6 p.
Notes on stalled fl y ing; by R . M. Hill and
H . L . Stevens. Aeronautical R esearch Com­mittee.
Oct., 1922. 9 p, Diag.
Resistance of fluids and j et reaction. In
French. Interna t ional Air Congress, Bel-gium.
1925. 10 p . Illu s .
Jet diffusion and jet deflection. Tr. by
J. Vanier from V ortrage auf dem Gebiete
der Hydro und ae rodynamik. T ec hnica l
Data Section, McCook Field. Dec. l, 1925.
4 p. Diags .
Periodic fluid flow b e hind cy linders. In-ternational
Air Congress, Be lg ium. 19 25.
2 p,
Motion of c y 1inders in a perfect fluid.
Tr. by F. W. Pawlouski. Technical Data
Section. Memo. report No. 180. Aug. 27,
19 25. 32 p. Diags ,
Flettner rotor s hip in the light of the
Kutta-Joukowski theory and of experime n ta l
res ults; by Frank Rizzo. Natio nal Advisory
Committee for Aeronautics . Technical note
N o. 228. Oct., 1 ~25 . 22 p, Photograph,
charts.
Effect of a rotating cylinder adapted to a
wing profile. In French. International Air
Con gress, Belgium. 1925. 9 p , Diag.,
c hart s .
Modification of the principle of c ircula ­tion;
T r . by .J. Vanier from proceedings of
fir s t Internat iona l Cong ress for applied
mec hanics, De lft, Holland, 1924. T ec hnical
Da ta Section, McCook Field. S ept. 22, 1925.
14 p . Diag.
On valve m ethod of m easuring small mo­tion
with special reference to the precise
recording of sounds, press ure - variations and
vibrations; by Juic hi Obata and Yahei Yos ­hida.
Aerona utical Research Ins titute, Vol.
1, No.11. Tokio. Aug.,1925. 15p. Diags.
Note on the Katzmayr e ffect, that is , the
effect on t he characteristics of an aerofoil
produced by an oscillating airstream. Aero­nautical
Research Committee. Reports and
Memoranda No. 969 . (ae . 185.) Mar., 192 5.
5 p. Charts.
Aerodynamic characteristics of a ircra f t
with r eference to their use; by L. Panetti.
Tr. from L'Ala d'Italia, Apr., 1925. N a ­t
ional Advisory Committee for Aeronautics.
Technical Memorandum No. 3 39. 1925. 12 p.
New method of calculating the aerodyna­mic
c haract eris tics of a biplane by Bruno
Eck. Tr. from Zeitschr ift fur Motorluft­schiffahrt;
by J. F. Vanier. In German with
translation. Tec hnical Data Section, Nov.
6, 1925. 42 p. Charts .
Recen t progress in the t h eor etical deduc ­tion
of airplane wings. By M. Panetti. Tr.
from R e vista Aeronautica, July, 1925. Ad­visory
Committee for Aeronautics. Tec h­nical
Memora ndum No. 338. Nov., 1925.
10 p,
Effect of the location of the main section
in the symmetric bi-convex profile of air­plane
wings. In French. International Air
t.:ongress. Belgium. 1925. 6 P.
Determination and class ifi cation of aero­dynamic
properties of wing sections; by Max
M. Munk. National Advisory Committee
for Aeronau t ics. Sept .. 1925 . 22 p .
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D00.12 / 425
R. & M .
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R. & M.;%3
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AlO 2/180
D 5 ~ .338/~4
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Vol. l ­No.
11
D00.12 /9 6
R & M.
Al0.'i3 1 / l
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D 52.33 / 113
D 52 .33 /114
D52.338;231
Pressure distribution on Joukowski wings.
Graphic construction of J oukows ki wing; by
Otto & Trcfftz, E. B lumenthal. Tr. from
Zeitsc h r ift fur Flugtechnik und Motor luft ­sc
h iffahrt, May 3 1, 191 3. N ational Advi­sory
Committee for Ae ronautics. Technical
Mem orandum No. 336. Oct., 1925. 20 p.
Charts.
L ateral stability; by H. R eiss n er. Tr.
from Z e itsc hrift fur Motorlufts chiffahrt,
1912, by J. F . Vanier. T echnica l Data Sec ­tion
, McCook F ield. Nov. 4, 1925 . 14 p .
Diags,
Graphic representation of the quaJities of
s tatic longitudinal stability : by F. Haus. In
French . Internationa l Air Cong res s, B e l ~
gium. Diags.
Calculations for rate of climb and loss of
speed. In French. Internationa l Air Con ­g
ress, B elgium. 1925. 5 p.
Fore and aft stability of airplanes. In
Fre n c h. International Air Congress, Bel-gium.
1925. 41 p,
Autorotation meas u rem e nts on mode l air­plane
with zero s tagger; by F . B. F radfield
and L. P. Coombes. Aeronautica l Research
Committee. Apr., 1925. 7 p. Charts, d iags.
8t1·ength calculations on airplan es. Tr.
fr om B~ri ·}1te und Abhandlungen d ~ r \V1s­sen
s chaftlichen Gessellschaft fur Luftfahrt,
July, 1925. National Adviso