Technical bulletin no. 34

              AIR SERVICE INFORMATION CIRCULAR
VOLUME V
(AVIATION AND AEROSTATION)
BY DIRECTION OF CHIEF OF AIR SERVICE
APRIL, MAY, JUNE, 1923
TECHNICAL BULLETIN
No. 34
NUMBER 427
DEVELOPMENT OF MILITARY AIRCRAFT MATERIAL FOR UNITED STATES
AIR SERVICE :UNDER SUPERVISION OF ENGINEERING DIVISION .
•
PUBLISHED BY
ENGINEERING DIVISION, AIR SERVICE
McCOOK FIELD, DAYTON, OHIO
1923
McCook Field-6 '.4-23-IM
CONFIDENTIAL
The information contained herein is confidential and therefore '
must not be republished, either in whole or in part, without
express permission of the Chief of Air Service, U. S. Army.
CONTENTS
AIRCRAFT DEVELOPMENT
AIRPLANES
Views and description of Boeing MB-3A-New Curtiss PW-8 Pursuit ........................ 4-9
GA-1 Changes- Flight Test of CO-I-Fokker C0-4-NBS-l's and Barling Bomber.... 10
Perfonnance Results on/ I'A-5 Training-Static Test and Improvement of TA-6........ 11
Aerial Ambulances, A-:( and A-2-Proposed Changes on R-3 and R-6 Racers for
1923 Pulitzer (views of R-6) .............. ............. . ... ........... ...... ... ...... ........ ....... ...... .... 12-16
Deidgni Detajl!l, .. of N~w J,-W-F Transport "T-3" .............. ........ ... .............. ........... ................ 16
AIRSHIPS AND BALLOONS.
Progress on RS-1 at Goodyear-Destruction of TC-1 at F. A. I. D....................... ....... .... 17
New OA-1 Airship Equipped for Gypsy Moth Experiment (views) ......................... , ... 17-1$1
High Altitude Balloon Cabinet-lmprovemenit to Terry Mast-Windbreaks................ 19
Grab Winch-7 M Gas Plant (view)-Investigation of Lift of Gases ..... ....................... 20-21
ARMAMENT.
New B-2 Bomb Racks-R-3 Release H,andles-Machine Gun Ground Test Support.: 21
New Wing Tip Flare Bracket, "E-2," with views and description .................................... 22-23
EQUIPMENT.
Km-C-Lac Celluloid Cleaner-Liquid Oxygen Container (Bureau of Standards) ........ 23
Standard Instrument Boards-Weston Luminous Ammeters-Exide "A-2" and Moore
"Dry Seal" Batteries-New Westinghouse Starter for Liberty.............. .................. 24
Shallow Tank Fuel Gage,--Gogglettes-Brass Goggles-Slide Rule for Gas Com­putations-
Night Field Marking for "T-2" Endurance, Flight.. . .... ......... ... ........... 2i.i
Portable Field Bl'acons- New Landing Light (view)-Landing Lights on NBS-l's
· (view)--K-5 Camera-Revised, Specifications for Field Photographic Trucks ...... 26-27
POWER PLANTS
ImprovPment of Lawrance J-1 Engine ......... .... .. ......................................... .... .................... 27
Wright Radial in DH-4B-1921 Liberty Engines for Service-Magneto Tests-Oil
Heater for V,Tin.ter Flying-New Specification for Fuel Hose-Supercharged
DH-4B Airplanes ...................................... .... .................. ............................................. ..... .. 28
RESEARCH AND EXPERIMENT.
RESUME' OF ENGINEERING DIVISION SERIAL REPORTS.
Stresses in Airplane Spars-Box Spars-Stresses in Drag Trusses-Airplane Per­formance
and Des'ign Charts on "Fineness," "Any Aerofoil," and "Maneuver-ability''-
Ferrule Ends for Streamline Wire ....... .................................................. 29-30
Nomographic Column Charts-Duralumin Spar for TA-4-Gun Sight "X-6"-Flex-ible
Floor Mount in DH-4B ...... ........................... ......... ......... .......................... ....... ........ 31
"T-1" -Transforming C:lmerra-Precimo Gyro Inclinometer-Schroeder Flowmeter.... 32
Perfor,m:inces: Loenin,g PW-2, Dayton-Wright TA-3 (110 LeRhone) and TA-5, and
Huff-Daland TA-6 ................................ .................... ,....................................................... 33
Speed and Ceiling of U.S. Army Airships-Chrome-Vanadium Steel No. 6120.......... 33
Manila Hemp Rope-,-Chrome-Molybdenum Steel Tubing-Aluminum Ingot ....... ......... 34
Cockpit Heater for Altitude Flying-Oxygen System for Supercharged Airplanes.... 34
Carburettor Test Chamber-Effect of Exhaust Back Pressure ... ~................... .. ..... ......... 35
INVESTIGATION OF MATERIALS.
New Coating for, Aluminum-Bearing Metals-Drillin,g Properties of Brass and,
Bronze-Bronze Ingot-Proposed Standard for Chrome-Vanadium Steel­Balsa
Wood in Aircraft Construction...... ........................ ............................... ............... 36
Inspection of Wood Parts in Air Service Storage Depots.................................................... 37
NEW BOOKS AND DOCUMENTS.
Dc.cuments Added to Engineering Divisipn Reference Files ... ... ........ ........... .,........ ... ..... ... 38
4 TE CH N I CA L E UL LET I N No. 3 4
BOEING MB-3A-PTJRSUIT
(Wright " H-3" Engine)
AIRCRAFT DEVELOPMENT
ON ENGINEERING DIVISION PROGRAM
AIRPLANES
PURSUIT
Boeing MB-3A.
Recent completion of two hundred MB-3A's by the Boeing Airplane Company, Seattle, \Vash­ington,
has pro-vided the Air Service with a new improved Tvpe I pursuit ai rplane frnm which the
fau lts of the earlier design, the Thomas-Morse MB-3, have been carefully eliminated. From time
to time as production on the Boeing contract advanced, numerous changes were· made in the new
design by the E ngineering Division as a r esult of service tests on completed articles; which changes
affected all of the MB-3A. airplanes in a more or less degree according to the nature of the change
and the feas ibility of application.
T he new Boeing MB-3A resembles the earlier T homas-Morse MB-3 in general appearance
except for its smaller wing area, new tail surfaces ( in stalled on la~t fi fty arti cles only), and the
side type radiators. The latter cha nge is the most noticeable as the MB-3 carri ed the radiator in
the upper wing. It may be cited that the Thomas-Morse MB-3 a irplanes now in the Service are
being modified for advanced t raining and will be designed "MB-3M" as stated in Techni cal Bul­letin
No. 33.
It has been previously mentioned in earlier numbers of Technical Bulletin, that two produc­tion
MB-3A airplanes built under the Boeing cont ract were delivered to the E ngineering Division
for 'test. One of these as a standard production model equipped with standard ( two ailerons)
wings and new tail surfaces , whereas the other was equipped with special ( four ailerons) wings of
modified section, special shock-absorbing engine bearers, and old style tail sur faces, the special fea­tures
befog designed a nd submitted by the contractor for comparative test. It is the purpose of this
MB-3A SHOWING NEW TAIL SURFACES, SIDE RADIATOR, AND CENTER SECTION.
6 T E C H N I C A L B U L L E T I N N o. 3 4
article to discuss the standard model only, but owing to lack of complete performance data 011 this
model, it 'became necessary to use the figures obtained 011 the special model as noted under "Perform-ance."
·
The standard Boeing MB-3A is an Air Service Type I , single seater pursuit airplane of ex­ternally
braced biplane construction. It is powered by a standard Wright Model H-3, 320 h. p.
engine, swinging either a two or four-bladed propeller. The structural features are briefly de-scribed
in the following. ·
Wings.-The two-bay cellule of the standard MB-3A has no stagger. It is an externally
braced structure with stre-amline brace wires and spruce interplane struts. The upper wing
which carries the gravity fuel tank and the water expansion tank is continuous with two ailerons
inserted in the trailing edge at the tips. The lower wing has two panels, which are attached directly
to the fuselage wing butt on each side. Wood constrnction is used thruout.
Fuselage.-This structure is of the conventional wood construction with laminated ash and
spruce longerons and wooden cross members braced by diagonal wires with turnbuckle adjustment.
The lower wing butt is built integral with the bottom of the fuselage which has a maximum
width of 3y; feet across this portion, the width of the fuselage proper being only 2.Yz feet with a
maximum depth of about 4 feet. Fabric covering is used on both wings and fuselage.
Tail Surfaces.-The new tail surfaces shown herewith are of wood construction with fabric
covering. The elevator is built about a box spar formed of hvo "I" section members with flanges
joined by means of plywood. Conventional "I"
section ribs made with spruce capstrips and ma­hogany
webs in which several lightening holes
are cut, are built on to the spars with the cap­strips
sen·ing as spacers.
NF.W TAIL SURFACES
The same construction is used for the stabi­lizer,
except that this structure employs two spars,
front and rear, which are not joined with ply­wood
at the top and bottom as in the case of the
elevator. This plywood, however, extends from
the front S]Jar forward to the leading edge on both
top and bottom. Lightening holes are cut in the rib webs and al~o in the plywood along the lead-
· ing edge.
The rndcler and fin are of wood construc­tion
also, the former consisting of one main box
spar composed of two members, an "I" section
and a channel section, joined by rihs of the same
design as those used in the elevator and by piy­wood
glned to top and bottom flanges. The fin is
constructed with a single laminated main spar, to
the upper part of which the rudder is hinged, and
two small auxiliary vertical spars of plywood to
which the ribs are joined. The leacling edge is
made of laminated spruce milled and routed to
shape. The whole structure is c9vered with 3-ply
mahogany plywood with large lightening holes cut
thrtt between the spars and ribs.
The general construction of the old style tail
surfaces ·wi.th the short vertical fin and balanced OLD TAIL SURF ACES
elevator and rudder is somew.hat similar to that used in the new surfaces. These are used on the
first one hundred fifty airplanes built under this contract.
Cha:,sis.-Spruce struts supporting a continuous streamline axle fitted with elastic cord shock
absorber and 28 by 4 inch straight-side wheels and Goodyear tires comprise the two-wheeled land­ing
chassis used on this airplane. The axie, proper, consists of two short shafts, one for each
wheel, supported between the spreader tubes. The structure is strengthened by vertical streamline
brace wires. ·
AIR C R A FT D E V E L OPMEN T 7
Power Plant-The power plant consists of a standard \.V right H-3 engine capable of deYelop­ing
320 horse power at a normal speed of 1800 r. p. m. The engine is fitted with one Stromberg
NAD-6A carburetor with standard mixture control effective to ceiling, and an automatic spark
advance, ignition being furni shed by two Dixie magnetos. ·
Fuel system comprises two leak-proof tanks, the main tank of 33 gallons capacity being located
in bottom of fuselage directly in front of pilot and the 12-gallon grav ity tank being placed in
center section of upper wing. Fuel is lifted from main tank by suction thru a line strainer to an
engine-driven bellows pump which forces it thru a 3-way cock directly to carburetor or to both
carburetor and gravity tank, the latter overflowing into the main tank. Gravity pressure alone
may Le used to operate system in case of pump failure.
\Vater cooling is effected by means of two side radiators of Thomas-Morse manufacture, sup­ported
on padded ash sills on each side of fuselage opposite cockpit. The expansion or reserve
tank, which is provided with an automatic pressure relief yaJve to prevent excessive loss of water
under adverse conditions, is placed in the upper wing. Part of the water which has been heated by
the engine, is circulated around the intake manifold , thus heating the gasoline mixture. Cooling
is regulated by shutters over radiators. These are controlled from the cockpit.
Equipment-In addition to the requisite flying equipment, this airplane carries oxygen and
radio apparatus, two life preserver cushions and fire extinguisher. Provision for carrying camera
. is made al so. Armament consists of two .32 caliber synchronized aircraft guns with necessary am­munition
boxes, chutes, and sights. One of the airplanes at McCook Field has been equipped with
electric landing lights and other night flying accessories.
Spare parts for Boeing M.B-3A airplanes, requested bv the Supply Division, Washington, D.
C., have been ordered by the Procurement Section of that Division upon recommendations made by
the Engineering Division in cooperation with Property Maintenance and Compilation Section, Fair­field
Air Intermediate Depot, Fairfield, Ohio. A contract for certain spares has been awarded on
a competitive basis to the Boeing Aircraft Company which is considered sole source of suppiy for
these parts, the balance of the spares will be covered by Circular Proposal. New part numbers will
be assigned, so as to distinguish the new spares from the old. Slight changes from standard -equip­ment
have been incorporated in the new parts with a vie,v of reducing maintenance difficulties to
a mmtmum.
CH ARACDERISTICS AND P ERFORMANCES.
DIMENSIONS
Overall span . .... ..... . .... .. . . . . . . . ... .. . . .. .. 26' 0"
Overall length .. . . . .. . . ... . . ..... . . . . . . .. ... . . . . 20' 0"
Overall height .. .. ... . .. . . .. . . ... : . . . . . . . . . . . . . . 7' 8"
Gap . . .. . . . . .. . .. . .... . . . .. .. . . ... .. . .. . . . . . . .. 4' 5~,;,i"
Stagger ...... .. ... . .. . . . . . ... . .... ..... .. . .. . . none
Sweepback .... ... . .. . . ... .. . ....... .. . . .. ... . . . none
Span of wings . .. . .. .. .. .- . . . . . . .... . . . . . . .. . . .. 26' 0" upper, 24' 6" lower
Chord of wings (same) . .. . . . . . . . .. . . . . .. . .. .. . .. 5' 3-3/ 16"
Dihedral . ... .... . . . .. . ..... .. . .. .. . . . .. . . . . ... . 3°
Incidence (upper wing) .. ..... . .. .. .. . . .. ... . .. . . 3° center, -40' tip
Incidence (lower wing) . . .. .... . . . . . .. . . . .... ... . -40' center, -40' tip
AREAS
Total supporting surface . . . . .. . . . .. ... . ..... . .... 228.55 sq. ft.
Ailerons (2) . . . . . . . . . . . . . . . . . . . . . . . 19.68
Upper wing . . .... . . ... .. . ...... . .. . 114.21
Lower wing . . . . . . . . . . . . . . . . . . . . . . . . 94.66
Elevator . . .. . . . . .. . . . . .. .. . . .. . . . . .. .. : ..... ... 17.0 sq. ft.
Fin .. .. . . ..... . . . . . . . . . .......... . . . . . . ..... . . 1.55
Rudder . . . .. . .. . .. : . . . . . . .. . . . .. .. . _ . . . ... . . . .. 7.632
Stabilizer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.12
8 T E C H N I C A L B U L L E T I N N o. 3 4
WEIGHTS
Empty including water . . . .. . ........ ... .
Ni ilitary load ... .. ....... . .. . . . .. .. . . . . .. . .. . . .
1717.18 lb.
767.82 lb.
Armament ........ . . .. .. .. . . . . ... . . 205.32
Equipment . . . . . . . . . . . . . . . . . . . . . . . . . 84.5
Crew .. ..... .. .. . . . . . . . . . . . . .. ..... 180
F uel . .. . . ....... . .... . . . .. . .. . . ... 264
Oil .. . .. . . . . . . . . .... . .. .. . .... .. .. 34
Gross weight . . ........ . ..... . . . . .. . ..... . . . .... 2485 lb.
Weight per sq. ft. (area) . . . . . . . . . . . . . . . . . . . . . . . . . 10.85 lb.
Weight per h. p. ( rated) . . . . ·. . . . . . . . . . . . . . . . . . . . . 8.29 lb.
PERFORMANCE*
CLIMB SPEED
Standard Time Rate Engine Level Flight
Altitude in inin. f t/ min. r. p. m. m. p.h.
0 1235 1650 140.6
6,500 6.7 855 1660 137.6
10,000 11.2 642 1655 134.5
15,000 21.3 362 1650 125.2
19,500 S. C. 44 100 1640 106.5
21,200 A. C. 0 1630 92.2
Endurance, full throttle at 10,000 ft.- 2 hr., 15 min. approx.
Minimum speed at sea-level-65.2 m. p. h.
Engine
r.p.m.
1850
1810
1790
1745
1675
1630
* The performance results herewith given apply to a standard MB-3A pursuit equipped with B oeing special
design wings (four ailerons) of same area (228.55 sq. f t. ) as standard model but of modified section and old -style
tail surfaces. This special model is slightly heavier in equipment (gr"oss weight 2 539 lb.) than the sta-ndard pro -
duction MB-3A on which no performance data have yet been obtained. ·
A summary of the flying qualities of the MB-3A airplane as taken from the pilot's observations
discloses a good performance and maneuverability at low altitudes but accessibility and mainten­ance
features are only fair. The airplane taxies and takes off easily and quickly with ready re­sponse
to control s. It lands fast yet easily with no tendency to ground loop or pancake, being
very sensitive to elevator. Stability is very good laterally hut somewhat unstable longitudinally
with tendency to dive or "hunt" at high speeds. Maneuverability is excellent with quick response to
all controls, particularily elevator. The airplane rolls, loops, and turns easily, holding steep banks
without falling off. It spins rapidly but responds imrnecliately to controls when reversed.
Curtiss PW-8.
A new pursuit airplane, known as the Curtiss P \V-8, was built for the Air Service by the
Curtiss Aeroplane and Motor Corporation, of New York. on a recently-awarded contract for
three airplanes, and delivered in April to Mitchell Field, Long I sland, where inspection and ac­ceptance
tests were conducted by representatives of the E ngineering Division, after which it was
flown to McCook Field, Davton, Ohio, for further tests and examination in connection with de­sign
recommendations on remaining articles. Later t his airplane was returned to the contractor
for extensive alterations for a proposed transcontinental daylight flight from New York to San
F rancisco, which necessitated removal of military equipment and increase in fuel capacity suffici­ent
to cover distances between refueling stations along the route.
The Curtiss P\ i\T-8 is a two-bay externally-braced biplane with thin wings of equal span ( 32
ft .) and symmetry and a steel tubular fuselage mounting the Curti ss "D-12" engine. Fabric
covering is used on fu selage and wings except upon central portion of continuous upper wing be­tween
the ailerons where the unique Curtiss patented wing radiators form the surface covering.
The design was derived from that of the Curtiss R-6 racer which now holds the vVorlcl's speed
records. The new pursuit plane has a speed in excess of 170 m. p. h. with military load.
i----- 10·-1o··c... -------i
1.--------------,lG.'(l'-------------..
BOEING MB-3A-PURSUIT
General Arrangement.
CHARACTERISTICS
Overall span _ ---- -- ---- -- ----- -- --- 26' O"
Overall length __ -- -- --- -- -- ----- 20' O"
Overall height --- -- ----- -------- -- 7' 8"
Aerofoil -------- ---- ------ --- - R. A. F. 15
Chord _,. _____ ___________________ ______ __ 5' 3i\-"
Supporting area ------------------ 228.55 sq. ft.
Gross weight------------------------ 2485 lb.
Military load ____ ______ __ ,. ________ 767.82 lb.
>
H
10 TE CH N I CA L B UL LET I N No: 3 4
GROUND ATTACK
Engineering Division GA-1.
Modifications of the GA-1 armored triplane which were discussed in detail in last issue of
"Technical Bulletin" are in progress in Engineering Division's shops. The first redesigned chassis
on which a single 44 by 10-inch wheel replaces the two 36 by 8-inch ,vheels formerly used, has been
completed and fitted. Construction on five revised chasses for GA-1 airplanes at Kelly Field,
Texas, is proceeding.
OBSERVATION.
Galludet C0-1.
On initial flight tests, the first production Gallaudet CO 1 all-metal airplane received recently
from the Gallaudet Aircraft Corporation of East Greenwich, R. I., attained a high speed of 120.8
m. p. h. at ground which is an improvement over the experimental model built by the Engineering
Division. (See "Per.forniance" on page 12, Technical Bulletin No. 27.)
To further improve this performance, a new propeller has been designed for the C0-1, as
the propeller used in first flight tests was designed for a DH-4 airplane and turned too slowly to
obtain maximum results. Full performance tests are under way.
Fokker C0-4.
Two experimental observation airplanes, Model C0-4, recently built and delivered to En­~
ineering Division hy _1\nthony H . G. Fokker, of Holland, have been performance tested. These
airplanes differ considerably both in appearance and in conslruction of the front portion of the
fuselage, one being equipped with a circular nose radiator and the other with side radiators. The
latter airplane, equipped with side radiators and drop-forged aluminum propeller designed by the
Engineering Division, attained a high speed of 121.8 m. p. h. in level flight at ground. The same
airplane equipped with -a wooden propeller attained a high speed of 122.3 m. p. h. The other air­plane,
with nose radiator, using a high lift wing and the same wooden propeller aforementioned,
attained a high speed of 125.8 m. p. h. under same conditions.
The "C0-4'' is of biplane construction employing wooden wings and steel tubular fuselage
structure. A standard Liberty "12A" engine is used for propulsion. All three airplanes have been
delivered on the experimental contract which is awaiting termination. No recent progress has
been reported on the five production COA's under construction in Holland.
BOMBARDMENT.
NBS-1.
Construction of eighty-five Curtiss and L-W-F Model NBS-1 night bombers has been com­pleted
at the plants of the respective contractors, the Curtiss Aeroplane and Motor Corporation and
the L-\i\T-F Engineering Company, both of Long Island, N. Y. Altho all of these airplanes have
been accepted by the Government, a shortage of certain equipment such as engine starters and stor­age
hatteries has prevented their delivery to the Service.
Some difficulties have been encountered on supercharger in stallations on the Curtiss NBS-l's,
twenty of which were thus equipped on the Curtiss Corporation's contract. The trouble was due
to use of too large a jet in the carburetor. A supercharger expert from this Division has l)een sent
to the Curtiss plant to supervise work necessary to make installations satisfactory and deliveries will
be held np until this work is completed.
One of the supercharged airplanes was flown to :McCook Field in ]\fay.
NBL-1 (Barling)
Assembly of the Barling Bomber, the large six-Liberty-engined triplane built for the Air
Service by the \Vitteman Aircraft Corporation, has been practically completed at Wilbur Wright
Field, Ohio.
AIRCRAFT DEVELOPMENT 11
Conditioning of the NBL-1 for flight has necessitated a great amount of work and conse­quent
delay, preparatory to the initial "take-off." Ground tests of the engines conducted d1:1-ring
June disclosed defective engine controls which had to be corrected. Tail surfaces and ailerons
were subjected to static test using a proof-load of 6 lb. per sq. ft., ·with satisfactory results. The
air controls were submitted to same test with equally satisfactory results. A test of the landing
gear wheels by the Division disclosed safety factor of only two which was considerably below re­quired
strength, thereby necessitating installation of new and stronger wheels before fli ghts can be
attempted. The large Palmer Aero Cord tires, size 1500 mm. x 300 mm., used on this airplane
are to be replaced by new Goodyear 54 in. x 12 in. straight-side tires, the latter being the largest
size tires built under the new Engineering Division specifications on the "Airplane Straight-Side
Tire and \Vhcei" p1:ogram.
TRAINING.
Dayton-Wright TA-5.
Performance results obtained on the new Dayton-Wright training airplane, TA-5, which was
delivered to McCook Field last March, are as follows :
~ig~ spee~l. at ground ............ . .. ... ..... . .. . .
Service ce1lmg ................... . . . ..... .... .. .
Absolute ceiling ... . ...... ....... . ........... .. .
103.8 m. p. h.
16,900 ft.
19,000 ft.
The TA-5, only one of which was built for the Division by the Dayton-Wright Company, is
a two-place, side-by-side seater biplane mounting a Lawrance J-1 radial engine of 200 h. p. It is
similar in design to the TA-3 airplane, the "Chummy" training model, constructed by the same
firm.
Huff-Daland TA-6.
Static tests of the Huff-Daland TA-6 tandem trammg 'plane, which is a redesign of an im­proved
TA-2 model previously constructed by Huff, Daland and Company, Inc., Ogdensburg, N.
Y., employing metal construction and a 200-h. p. Lawrance J-1 engine, have been completed by this
Division with following results :
Fuselage held required loading satisfactorily to a fact~r of 7 with only minor failures
whereas wings in low incidence loading held to factor of 5 when failure of ribs occurred.
The spars were apparently strong enough at this loading altho a factor of 5.5 is required. In
high incidence condition, the spars failed in bending at factor of 7, one point below required
loading. In reverse position, failure did not occur until required factor of 3.5 had been
reached. Horizontal control surfaces were unsatisfactory due to failure of elevator box spar
below required loading altho a new walking- beam of Engineering Division design was in­stalled.
The vertical tail surfaces held required loading of 30 lb. per sq. ft. at which load.
the rudder became badly distorted.
On performance test, the TA-6 attained a high speed of 114.2 m. p. h. at ground, at 1710
r. p. m., a service ceiling of 18,550 ft. and absolute ceiling of 20,600 ft. For comparison, it may
be cited that the prototype model T A-2 with smaller Lawrance engine of 140 h. p. attained a high
speed of 114.1 m. p. h. at 1640 r. p. m. altho it fell considerably below the TA-6 in ceiling, the
service ceiling being only 15,850 feet. (For per.fonnance of TA-2 sec Technical Bulletin ]\To. 29.)
Further improvement and refinement of the T A-6 airplane for advanced training is assured
by a new contract just awarded by the Division to Hnff, Dalartd and Company, originators of this
design. The principal· changes include a complete new in strument installation, new tail and wing
skids, new streamline engine cowling and exhaust manifolds and replacement of rigid elevator
controls by flexible cables. Longitudinal stability is to be improved either by in stallation of new tail
surfaces or by changing angular setting of wings with respect to the fuselage, thus insuring longi­tudinal
stability or normal flying attitude with controls free, with or without power, thruout the
entire range of flight.
12 T E C H N I C A L B U L L E T I N N o. 3 4
MISCELLANEOUS TYPES.
Ambulance Airplane, Model A-1.
Design drawings and other procurement data have been completed for the construction of a
new airplane ambulance in accordance with the Engineering Division's design recently approved by
Chief of Air Service, ·washington, D. C.
This airplane which is to be designated "Air Service Ambulance A-1 ," is to be of biplane con­struction
mounting a standard Liberty "12-A" engine. Provision is made for carrying a pilot,
medical officer, and two patients. A new type of litter designed by the Engineering Division will
be used. It is likely that bids will be asked for the construction of several airplanes of this type
within a short time.
Ambulance Airplane, Model A-2.
For tlie purpose of demonstrating the possibilities of using large passenger transport for
aerial ambulances, the Air Service Transport T-2, the passenger model described and illustrated in
Technical Bulletin No. 33, was converted into an airplane ambulance in the Division's shops at
McCook Field and flown to Bolling F ield. \i\Tashington, for exhibition at the recent Shriner's con­vention.
The modifications included remov3.l of seats and other equipment from the cabin of the air­plane
and the installation of ambulance equipment consisting of two ambulance litters, seat for
physician , running water, wash basin , and storage tank, and electric ceiling and side lights with
battery for supplying necessary current. An airplane clock, thermometer, and altimeter were also
installed and ideal Joca.tions marked out for medicine cabinet, crash tools, and other fir st aid ac­cesso,
ries. The cabin· was lined with white material and provided with oak flooring covered with
linoleum. Red Cross in signia were painted on the fuselage, wings, and rudder of the airplane.
Air Service Racers.
Interest in racing airplanes, particularly prospective Pulitzer entries, ma nifests itself more
keenly w'ith the advent of the National Airplane Races to be held in St. Louis, Mo., this corning Oc­.
tober. In this connection, a brief discussion of the proposed changes and recent performances of
two Army Air Service racers. the Curtiss R-6 and the Verville-Sperry R-3, both of which will
very probably be entered in the 1923 Pulitzer Race, appears most opportune.
Model R-3.-Extensive changes have been proposed by the Engineering Division to improve
performance of the Verville-Sperry Racer, one of which took fifth place in the Pulitzer Race last
year. T he proposed changes include installation of a Curtiss D-12 engine and Curtiss wing-surface
radiators of the same type as those used on the R-6 racer, which should result not only in in­creased
performance but also in increased safety for pilot. It is probable that an entirely new
and narrower fuselage of improved streamline shape will be constructed and a more carefully
streamlined landing gear installed. It has also been proposed to build a new wing using USA-35
aerofoil section with smaller area and span so as to decrease vibration that is noticeable in present
wing at high speeds, but at the same time keep landing speed within the P ulitzer race limit of 75
lll. p. h.
The present Ver ville-Sperrv racer, three of which were built for the Pulitzer race last year by
the Lawrence Sperry Aircraft Company, Inc. , Farmingdale, N. Y., was designed by the En­gineering
Divisinn with a view of obtaining data regarding use of this type for fast pursuit purposes.
The R-3 is a thick wing monoplane of the Junker type with welded steel tubular fu selage structure
and large tapered wing ·of wooden construction attached in lower position. ;rt is fitted with a re­tractable
chassis. by which each wheel may be folded inward and upward into a recess in the under
side of the wing.
The power plant consists of a high compression \:Vright Model H-3 engine, water-cooled by
two Lamblin radiators suspended below fuselage to rear of engine. Fuel from a 40-1;allon tank
located in fu selage, is supplied to carburetors by an air pressure system.
A IR C R A F T D E V E L O P MENT
The general characteristics of the R-3 racer are as fol lows :
Span ... .. . ... . ...... . . .. . . .. •...... . .... .. . .. .. .. .
Length . .... . .. . . . . .... . .... . .. . ... . ... . .... ... . . .
Height . .. .. .. ... . .. ..... . .... . .. . . . . .. . . . . ... .. . . .
Total Area . ... . .... . . . . .. .. . ... .... . .. . . ... · .. . .... .
A.. erofoil . .. ..... . . . . . . . . . .... ...... . ... . .. . . . ... . . .
Incidence ... . . .. . . . . . ... . .. . ........ . . . ..... .. ... . .
Chord ( tapered wing) . . . . . ... . . . . . .. . ....... . .. ... . .
Weight empty ...... . . ... .. . . .. . . . . .. . ... .. . . .. . .. . .
Useful load . ... . . . . .. . ........ .... . . . .. . .. . . . .... .
VVeight per sq. ft. (aera) .. . .... . .. .. ... . .. . . . ...... . .
Weight per h. p .. . . . . .. . ... . . . . . ... . . . .. . .... . ..... .
29' 3"
22' 5"
7' 1"
144.30 sq. ft.
Mod. NACA-81
-10
root 94", tip 35 .2"
1892.S lb.
488 lb.
16.S lb.
5.96 lb.
13
Of the three fodel R-3 racers entered in the Pulitzer contests last vear, one fini shed in fifth
place at average speed of 181.2 m. p. h .. another made 178 rn . p. h. anci' the third 168.9 rn. p. h.,
before being forced down on fourth lap. In the calibration tests conducted· by the Engineering
Division at '\Vilbur \ \!right F ield during the early part of the present year, a maximum high speed
of 191.1 m. p. h. was attained with chassis retracted and 162.8 m. p. h. with chassis extended in
normal position. On March 31 , 1923, an E ngineering Division pilot established a new \Vorld's
distance record in the R-3 for SO kilometers ( 310.685 miles) OYer t riangular closed course about
Wilbur '\,Vright Field, New Carli sle, and Dayton, Ohio, in 1 hour, 51 minutes, 5.18 seconds or at
average speed of 167.807 rn. p . h. It is estimated that proposed modifi cations if carried out wi ll in­crease
present high speed of this airplane approximately 40 m. p. h.
Model R-6.-The Curtiss R-6 racer, two of which were built by the Curtiss Aeroplane and
Motor Corporation, of Garden City, New York, for the 1922 P ulitzer Race at Detroit, Michigan .
has the distinction of being the '\i\Torld's fastest airplane as a result of the one-kilometer speed
record establi shed by Lt. R. L. Maughan at ·Wilbur Wright F ield on March 29, 1923.
The design embodies a thin-wing. ex ternally-braced biplane cellule with monocoque fuselage
mounting a Curtiss "D-12" engine. '\i\Toocl construction is used for wings which are symmetrically
built with ronted multiple spars and wooden ribs supporting a very thin veneer covering over which
the wing surface radiators are attached. Thin strips of wood laid diagonally and braced by bulk­heads
and longerons, form a beautifully streamlined monoco<jue fu selage. T he control surfaces .
ailerons, elevators, and rudder, a re of metal construction with fa bric covering, the lower part of
CURTISS R-6-RACER
(Curtiss "D-12" 375 h. p·. Engine)
14 T E C H N I C A L B U L L E T I N N o. 3 4-
the rudder completing the tail streamline of the fuselage. The offset vertical fin is of wood con­struction
similar to that employed on the wings and fuselage. The ailerons are actuated by rigid
control· tubes extending along axis of hinge inside of wing.
The power plant consists of the newly developed Curtiss D-12 a ircraft engine fitted with
special speed propeller and spinner. The engine is carefullv streamlined in the oval-shaped fuselage
which has maximum cross-section of 28.5 inches by 38.5 inches at this point. The normal rated
horsepower is 375 at 2000 r. p. m. as equipped with two Zenith U. S. 54 mm. carburetors and two
Splitdorf SS-12 dual magnetos. (Special Stromberg carburetors and special propeller .were used
in establishing one-kilometer speed record). Fuel capacity of 46 gallons is contained in two tanks,
the main tank holding 38 gallons and the reserve. 8 gallons.
GENERAL CHARACTERISTICS.
DIMENSIONS
Overall span ... .. .... .. . • .... .. .... ..... .... ... .. . . ....
Overall length . ...... ... . .... .......... . . . .. . .
Overall height .. . ..................... . ................ .
·wing span (upper and lower) ............... ...... . . .. .. .
·wing chord ( uppe1· and lower) .... . .. . . ... ..... .. ....... .
Incidence .. . . ............... ·. .. ... _. . . ... . ... . . .... .. . . .
Dihedral .... . ...................... . . .. ....... . .. ." .... .
Gap . ...... . ............... . ...... ...... ...... . ....... .
Stagger ......... . .... : . . ........................... . . .
Aerofoil . .. . ...... . ..... . .. ......... . ................. .
Tread .. .. . ... . . .... ............ .. .. . ................. .
AREAS
Total supporting surface .............. . ................ .
Upper wing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63.94
Lower wing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59.62
Ailerons ( 4) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.04
Axle fairing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.31
Elevators ......................... . ...... . ..... .
Fin (vertical) ........ .. .................... . ........... .
Rudder ........ . .. ... ............... ... . ... ........... .
Stabilizer ... . ..... ........ ........... .. .. . ......... . .. .
WEIGHTS
Empty (including ,vater) ..... ~ ............ .. ...... : ..... .
Useful load . . .. . . . ..... . ... .. ....... · .... .. ............ .
Fuel . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . 303
Oil . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . 22.5
Crew . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180
Gross weight .. . ... .. ....... . ..... . .. . ....... ......... . .
Weight per sq. ft. (area) .. .. ........................ . ... .
Weight per h. p. (375@ 2000) ......... . ................. .
19' 0"
18' 10-1 / 2"
7' 7"
19' 0"
3' 10" oo
oo
3' 10~1 /2"
7-1/2"
C-27
4' 10-1/ 2"
135.91 sq. ft.
6.56 sq. ft.
4.25 sq. ft.
4.97 sq. ft.
10.84 sq. ft.
1615.5 lh.
505.5 lb.
2120 lb.
15.851h.
5.66 ib.
Altho the Curtiss R-6 racer has no particular value for military purposes and cannot be con­verted
into a miitary type without a complete redesign, it is a particularly good racing airplane,
and, for that reason, the Engineering Division has proposed two methods for boosting its perform­ance.
As a result of wind tunnel experiments, it is indicated that the Sloane wing section used in
the Curtiss Navy racers is slightly superior to the C-27 wing section used in the Curtiss Army
racer. If the Sloane section wing of the same area were used ( which substitution could be ac­complished
without structural difficulties), the landing speed would remain unchapged and an in--
crease in high speed result. · ·
Another method for increasing speed might be used by reducing wing area with consequent
increase in landing speed. Since -the maximum landing speed for racers has been arbitrarily speci-
CURTISS R-6-RACER
GPneral Arrangement
CHARACTERISTICS
Overall span .. ............ .. ....... 19' O"
Overall length .... .. ....... .. ... .. 18' 101h"
Overall height ... ......... ..... ... 7' 7"
Aerofoil .......... .. ........... ......... C-27
Chord ......... ........................... 3' 10"
Supporting area .... : .. ...... ..... 135.91 sq. ft.
Gross weight ... ... ........ ......... 2120 lb.
Useful load ... .... .... .. ........... 505.5 lb.
",.!,
>-
H
?:I
n
?:I
>-
>Tj ...,
tJ
~
-<
~
L'
0
>,j
~
~ .z..,
.....
<.Jt
16 T E C H N I C A I. B U L L E T I N N o. 3 4
fiecl as 75 111. p. h. , it follows that maximum performance is limited by wing area. For the R-6,
the actual landing speed is believed to be several miles per hour slower than the figure computed
from wind tunnel data. This would permit an increase in high speed of at least one mile per hour
for every mile-per-hour increase in landing speed caused by reduction in wing area. Actual land­ing
speed could be determined from flight tests, thus furni shing data on which smaller wings could
be intelligently designed.
The following records established with the Curtiss R-6 racer, have been or will he homolo­gatecl
by the Federation Aeronautique Internationale thru the National Aeronautic Association, the
official representative body in this country.
DISTANCE ( CLOSED CIRCUIT)
100 km. (62.137 mi.) in 18 minutes, 6.78 second5, or 20.S.3 m. p. h.
Made IJy Lt. R. L. :Maughan at Selfridge F ield; .Michigan, October 14, 1922.
200 km. ( 124.274 mi.) in 36 minutes, 12.17 seconds, or 205.9 m."p. h.
Made by Lt. R. L. Maughan at Selfridge Field, Michigan, October 14, 1922.
MAXIMUM STRAIGHT-AWAY SPEED.
1 km. (0.62137 mi.) <1t 380.751 km/ hr. or 236.587 m. p. h.
Made by Lt. R. L. Maughan at Wilbur Wright Field, Ohio. March 29, 1923.
Note: On same elate, a record of 1 km. at 239.95 m. p. h. made by Lt. L. Maitland at
\Vilbur vVright Field in Curtiss Racer R-6, was ruled out by the N. A. A. officials for the
reason that pilot did not maintain horizontal flight thruout trials : One lap with wind was
made at 281.4 m. p. h.
Attempts to establish a record for the new F. A. I. Three-Kilometer Straight-Away which was
created April 1, 1923, by that association to supersede the One-Kilometer Course, have been tem­porarily
abandoned partly on account of minor accidents to racers during preliminary trials over
the new course and partly to other projects requiring immediate attention.
Air Service Transport "T-3."
Contract for ten new transport airplanes, Model T-3, has been awarded to L-\i\T-F Engineering
Company, Inc., College Point, Long Island , N. Y., for delivery to l\Iitche!l Field, from which
future allocation will be made.
This transport is designed to carry two pilots and six passengers together with their baggage
( about 50 lb. per passeioger). lt may be used for carrying freight also in which case the seats can
be easily removed. By provision in the contract, doors or traps are to be made of sufficient size to
permit loading of a Liberty or Wright ::teronautical engine without the use of hoists.
The de~ign embodies a two-bay, externally-braced biplane construction with sectional and
symmetrical wings and wide-tread landing gear. The power plant is to consist of a single Liberty
"12 A" engine mounted in nose of fuselage with shuttered radiator beneath. Two crash-proof fuel
tanks will be placed in center section of upper wing in such locations that they will not extend over
the portion of fuselage directly beneath. The cockpit accommodates two pilots, who have access to
the cabin, and is located directly behind the engine and forward of leading edge of wing, thus af­fording
maximum visibility forward .
The cabin is large enough to accommodate six passengers and their luggage for which a sep­arate
compartment has been provided. On each side, two windows with drop or sliding sash and
door with fixed window will prO\.;cle light and ventilation. Entrance to cabin is made on port side
only, steps and hand rails being provided for this purpose. Forward from rear wall of baggage
compartment, the fuselage is to be covered with corrugated duralumin sheeting up to the window
sills whereas fabric is to be used above_ sills and over top.
Conveniences and other special f eatures for comfort and safety of passengers include up­holstered
seats, individual safety belts and life preserver cushions, and toilet facilities with pressure
tank and wash basin similar to those provided in standard railway Pullman car. Seat-type para­chutes
are to be worn by each occupant. The cabin will be heated by hot air radiated from air
scoops surrounding the exhaust pipes, the heaters extending along entire length of cabin floor on
both sides. Exhaust pipes are carried aft and are constructed so that no exhaust gases can pos­sibly
enter cabin.
AIRCRAFT DEVELOPMENT
- General characteristics of the "T-3" are briefly stated as follows:
Span ..... . . ... . ..... .. .. . .. . . . . ....... . .. ... .. .. . ... . .
Length ....... . .. ..................... . . . . . ............ .
Height . .... ... ..... .............. . ..... . . .. . .... .. .. . . ·
Wing area including ailerons . ... ....... ...... .. . . ... . .... .
Chord of wing .. . . . .. .. . . .......... . . ....... . .. .. . . ... . .
Tread .. . ... . ... ... ........ . . .. ... .. . ... . .... .... ... . . .
54'
41'
13' 3"
760 sq. ft.
7' 6"
14' 9"
.17
In keeping with En'gineering Division's new policy in construction of large airplanes, static
tests of all important members will be made prior to 111.anufacture and assembly of fir st airplane,
thus eliminating considerable expense, time, and eventual destruction involYed in the usual static
testing of first physical model.
AIRSHIPS AND BALLOONS
RS-1 Airship.
Revised stress analysis of · keel for RS-1 semi-rigid now building at Goodyear Tire and Rub­ber
Company, Akron, Ohio, has been completed by the contractor and checked by the Engineering
Division which has forwarded it to the National Advisory Committee for Aeronautics. Stress
analyses of nose cone, control and power cars. and landi~g gear as practically completed.
Mock-up of control car with model equipme1i.t installed has been completed and ready for in­spection.
\iVater model tests of airship and design drawings of envelope have been completed and
appro'1ed by t his Division. Arrangements are being made for conducting extensive tests on keel
members of different strengths to determine whether present method of forming heavy gage dura­lumin
is practicable for these columns.
A SO-hour test has been completed by the Division at McCook Field on a power transmission
for this airship. The Goodyear Company is furni ~hing three transmissions under separate con­tract.
TC-1 Airship.
Airship TC-1 , the first of the new Class "C" training airships, was flown from Scott Field, ·
Illinois. to the Division's Airship Mooring Station at vVilbur vVright Field, Ohio, in May. The
airship was moored to a Terry mast equipped with experimental huffer, design No~ 3, for a period
of about fifteen hours. The mast functioned sati sfactorily during this test.
Early in June, the same airship upon completion of a second flight from Scott Field to Wilbur
Wright Field was destroyed while being moored to the same mast during a wind aml electrical
storm. The accident was caused, primarily, by breaking of mooring cable attached to nose of air­ship,
which allmved the airship to be blown against the Omaha mooring mast, nearby, where the
envelope was torn and ignited, apparently by discharge of static electricity from envelope to mast.
Investigation of the accident disclosed that the airship would undoubtedly ha.ve ridden out the storm
if it had not been for failure of mooring cable. The Division 'is making some minor improvements
to shorten time required for attaching airship to mast and for anchoring it safely. These changes
are discussed under "Improvement to T erry Mooring Mast" on page 19.
The second newt Class "C" airship, the TC-2, is completed and ready for its trial fl ights at
Wingfoot Lake, Akron, Ohio, preparatory to bei1ig flown to Aberdeen Proving Grounds, Mary­land
, where it will replace the "C-14" now being used for bombing experiments by the U. S.
Ordnance Department. The third airship, the T C-3, is about one-half completed by the contractor,
the Goodyear Tire and Rubber Company.
· OA-1 Airship (formerly "U. S. M. B.")
The first trial flights of the new observation, twin-engined airship, USMB, now designated
"OA-1," were made in April. Several changes in control surfaces were found necessary to obtain
the most effective combinations. The envelope was deflated in June as a result of excessive dif-
18 TECHNICAL BULLETIN No. 34
fusion , the purity of the hydrogen gas at time of deflation being only 70 per cent. It was found
upon examination by means of purity tests and diffusion meter that the gas film of this envelope
had deteriorated to the extent that the purity of the gas could no longer be maintained. A spare
envelope was subsequently installed.
NEW OA-1 NON-RIGJO AIRSHIP
(Formerly designated "U.S. M. B.")
Recently, the OA-1 air ship was equipped with a hopper fo r · scattering insecticide and flown to
Henniker, N. H., for cooperation with U. S. Department of Agriculture, Bureau of Entomology,
in their efforts to exterminate the Gypsy Moth, which i8 ravaging the New England States. Port­able
mooring mast. hydrogen apparatus, and other servicing equipment were shipped in advance to
the scene of operations.
Owing to the belated departure of the airship on its moth-exterminating expedition, caused
by unforeseen deficiencies in rigging attachments and gas valves of the. spare envelope that had
been 'in stalled, it is thought little can be accomplished in eradicating these pests, which have grown
to full size. However, the Department of Agriculture recommended that the "OA-1" proceed to
New England for trial operation of distributor and to prove its utility for this service.
CAR OF NEW OA-1 AIRSHIP
Ins ecticide Hopper in Insert
AIRCRAFT DEVELOPME~T 19
DESCRIPTION OF HOPPER USED IN GYPSY :\10TH EXPERIMENT.
The hopper used to distribute the arsenate of lead in the Gypsy :Moth Experiment was speci­ally
constructed to fit the forv.rard cockpit of the U. S. l\L B. airship , as shown in the insert on the
preceding page.
The de,·ice consists of a chamber for holding the poi son, an outlet through which the poison
is di stributed. and two air intakes. The main air intake consists of a ten-inch tube which takes air
from one of the propellers and exhausts it into the poison outlet on the inside of the hopper. This
flow of air carries the poison out through the oufet and breaks it up into very minute particles. A
valYe located between the air line and the outlet p ermits regulation of the amount of poison to be
n~ed.
Another air intake is located behind the propeller and exhausts its air against the bottom of
the hopper, through numerous small tubes located at varying distances above the bottom. The pur­pose
of this air system is to prevent the arsenate of lead from sticking to the walls of the hopper.
An agitator, driven by a sm;ill propeller, is located in the outlet and revolves at a high rate of
speed for the purpose of breaking up ~my large chunks of poison which might not be broken up
by the air flow.
The hopper has a capacity of 400 pounds. This quantity is suff icient to cover 16 acres of
wood land.
Cabinet for High Altitude Balloon.
A contract for construction of a balloon cabinet for use in high altitude flights has been
awarded to the Eberhart Steel Products Company, Buffalo. '.\l . Y. The cabinet is constructed of
aluminum and duralumin and is provided with windows especially designed to resist frost forma­tion
at high altitudes. Ballast is carried in a hopper in tLe form of shot which may he released
without danger of clogging or freezing.
The cabinet is ai r-tight and is designed to w:thstand internal pressure of ten pounds per
square inch. T he valve and rip panel cords are operated by shafts passing thru air-tight joints in
~iall of cabinet. Altho it weighs only about 500 pounds it is capable of carrying 4.000 pounds of
ba llast.
Improvement of Terry Mooring Mast.
The follow ing improvements to the Terry mast are being made by the Division to co rrect
defirienrie~ n0ted as a result of the recent attempt to moor the new TC-1 airship during a severe
electrical storm which destroyed the latter : .
( l ) A shield is to be provided to prevent mooring cable from slipping off of sheave at
base of mast, which caused the cable to break and allowed airship to r\ri ft free, thus
foui i11g with the Omaha mast.
(2) Additional gear reductions are to be placed on the double-purchase hand winch so
that airship may he hauled to the mast at greater speed .
<3 ) A brake band is to he installed on the top turning portion of the mast to restrict
circular movement of buffer arrangement in a horizontal plane, thus holding buffer
concentric with mooring line and retarding t he continuous fl y-wheel motion which
occurs when buffer runs free.
Early in April. the Terry mooring mast was erected at the DiYision's Airship Mooring Sta­tion,
at Wilbur \Vright Field, for testing new types of buffers and to provide station with mooring
equipment for handling the newly-proposed Lighter-than-Air transport service. A special device
attached to the buffer permits the airship to be "gassed" while moored to the mast.
Windbreaks.
The Engineering Division has prepared a n ew set of drawings for the Type R windbreak,
formerly called McKinley Type or Type A, on ·which all changes found advisable from tests of
original equipment have been incorporated. A set of blueprints will be sent to Naval Aircraft
Factory thru the office of General Inspector of NaYal Aircraft at McCook Field, for their infor­mation
in connection with an -inquiry made by the Navy to the Goodyear Tire and Rubber Com­!)
any concerning this equi pment.
20 T E CH N I CA L B U LL ET I N N o. 3 4
Drawings have been completed for a Type AP windbreak, which is similar to the Type R
windbreak, for adaptation to Type AP balloons. Purchase of one for test is contemplated.
An · experimental wind screen of the turntable type for use with non-rigid airships has been
designed and is to be erected at the Airship Mooring Station, Wilbur Wright Field, within a short
time.
Grab Winch.
A contract has been rece11tly awarded to the Steel Products Engineering Company, Springfield,
Ohio, for construction of one experimental grab winch for ground-handling of airships by me­chanical
means.
The purpose of this apparatus which may be operated by one or two men, is to eliminate the
large number of me.n now required in handling airships upon taking flight or in landing. It is
designed to grab hold of the drag rope dropped from the airship, hauling it down at desired speed,
holding it stationary, or playing it out slowly as occasion demands. The hauling-down apparatus is
to consist of two small track layers opposed to each other and running in a vertical position, the
distance between them being automatically regulated by the thickness of the drag rope. The pres­sure
or "squeeze" between these tracks which are so arranged that they can be easily and instantly
separated for quick release, is automatically controlled by the load on the rope. The main
vehicle is of the track-laying type, each side· being driven by the same motor but independently
7M CONTINUOUS HYDROGEN GENERATING PLANT
. AIRCRAFT DEVELOPMENT 2i
controlled. One side c:an be driven forward while the other is reversed, thus affording a very short
turning radius. Steering is accomplished by means of pedals arranged to minimize the number
of operations required by the operator.
7 M Gas Plant.
The 7 M continuous gas-generating plant, so-called because it is capable of producing hydro­gen
gas by the Silicol process continuously at the rate of 7,000 cubic feet per hour, has functioned
very satisfactorily in the recent tests at this station. It was found that this plant requires one cine­third
as much water as other generating plants of the same type and that it can be operated by
two men, whereas, heretofore, four or five men have been employed, which features show a great
improvement in increased efficiency and ease of operation of the new plant over the present stand­ard
service equipment. A view of the new generator is sho.vn on the opposite page.
For portable purposes, the plant which is very compact may be mounted upon a standard
three-ton truck and driven thru the truck transmission. As a stationary unit, it may be set up in
the field or 'installed in a railroad car, in which case a. small power plant is provided.
The plant is equipped with a specially-designed silicon grinder which permits wet, dry, or
lumpy silicon to be fed to the generator in a smooth, well-spread stream under control of the oper­ator.
The gas is dried by passing it over trays of lime which absorbs the moisture. The trays can
be cleaned and refilled by temporarily passing the gas around the drier. Continuous operation is
effected thru the dumping of the sludge without shutting clown the plant.
Investigation of "Lift of Gases."
The Division has recently completed a document on "The Lift of Gases in Practical Balloon
and Airship Operation," the purpose of which is to provide some practical and easy means of
rapidly and accurately calculating the static lift or buoyancy of a balloon or airship under various
atmospheric conditions, both at the surface and at various altitudes; also to calculate the percentage
of envelope fullness at the ground required to attain complete fullness at a given altitude without
loss of gas by valving. Proper account has been taken of various correction factors for impurity
of gas, "Superheat," and humidity. In addition, a systematic study has been made of average
seasonal atmospheric conditions over the United States to determine variation of lift with lati­tudes
and longitudes which vary appreciably in absolute moisture content. From these investiga­tions,
certain values have been established as being fairly representative of the "standard lift" cor­responding
to the so-called "standard atmosphere."
ARMAMENT
New "B-2" Bomb Rack for DH-4B.
Several old Mark XVI external bomb racks designed and built by the Ordnance Department
have been received from Langley Field, Virg.in~a, for conversion into Type B-2 racks for applica­tion
to DH-4B airplanes. These racks are being rebuilt with new metallic support beams and
safety devices and are designed to carry either two 100-lb. or two 300-lb. demolition bombs.
Bomb Release Handles, Type R-3.
The work of conditioning Type R-3 bomb release handles which have been returned to the
Engineering Division from the Service for reworking. is proceeding under priority order as re­quested
by Chief of Air Service. A number of handles have already been completed and · shipped
and the remainder will be shipped upon completion as soon as their disposition is known.
Airplane Support for Machine Gun Ground Tests.
An adjustable support has been made for attachment to tail skid of an airplane to hold it in
the desired position for testing machine guns on the ground. In order to properly conduct firing
tests on the ground, it is necessary to elevate the tail of the airplane so that the machine gun fire
can be directed at the target.
22 T E CH N I CA L B UL LET I N N o. 3 4
New Wing Tip Flare Bracket, Type E-2.
A ne,v wing tip flare bracket known as Type E-2, has been recently designed and built by the
Engineering Division for night landing purposes, particularly for use c,n monoplanes. The bracket
which is shown in the accompanying. illustration holds the standard Air Service Mark I airplane
flare candle in a horizontal position in such a manner that the glare of the candle is shielded from
the pilot's eyes. This particular feature is attained by an adjustable bracket which may be easily
adapted to the airplane wing upon which it is mounted.
MODEL E-2 FLARE BRACKET
The device consists of an aluminum retaining
bracket carrying the guide and clamp at its lower
encl for holding the candle and an adjustable
bracket riveted to its upper end for mounting to
the wing. T he mounting bracket is of steel and
is assembled to retaining bracket by means of a
latch spring and shoulder ri vet. The deflector or
shield which is bolted to the retaining bracket,
consists of a body, reinforcing .strap, and bead­ing,
made entirely of steel. The electric ter­minals,
insulated with reel fibre bushings and
washers, are provided to ignite the candle which
is held in the clamp by bolt and wing nut.
The "E-2" bracket may be installed on any
airplane of the biplane type now in the Service
by using the mounting holes already provided for
,he Fl alt . wing tip flare bracket. On the mono­plane,
it should be mounted about one-fourth of
the distance inward from wing tip and about one­third
to rear of leading edge on the wing chord
( front spar. ) The lateral position provides
safety in case of banked wings in landing and
the position to rear of landing edge reduces re­flection
from the revolving propeller blades to a
minimum. The flare is controlled by use of the
standard Type C Holt fla re push button control panel which should be mounted upon right side of
pilot's cockpit. This recommendation for location of control panel is made to obtain unifor mity in
installation of controls for night-landing equipment.
LANDING LIGHT, E-2 BRACKET, AND HOLT FLARE INSTALLATION ON DH-4B.
A I RCRAFT D E V E L OPM E NT 23
Interesting points brought out in recent tests conducted by the Division are that the Mark I
flare candle actually burns longer and more brilliantly when carried in a horizontal position and
that the adjustable bracket provide to be an effective means of shi elding the pilot's eyes from the
intense glare of the burning candle.
In order to determine the comparative meri ts of the electr ic landing light. the H olt wing
tip flare bracket, and the new· Type E -2 bracket, the three devices were mounted side uy side upon
the lower wing of a DH-4B airplane as shown at bottom of opposite page. Landings were made at
night without the aid of auxiliary field illumination in the fo llowing manner :
a. Electric landing light- ( fir st ) one on, (sec·ond ) both on.
b. "E-2" Flare bracket-(fir st ) one on, (second ) both on.
c. Holt flare bracket- ( fi rst) one on.
As these landing were made in rapid succession under same atmospheric conditions, it is be­lieved
that accurate results were recorded upon the merits of the respective devices as follows:-
a. Satisfactory landings were made by use of one or both electric landing lights.
b. Satisfacto ry landings were made by use of both E-2 fl are brackets. In comparison with the
electric landing lights, the Type E -2 ])rackets might be considered only 25% as efficient for
landing purposes for the reason that altho the Yolume of light obtained from the flare is far
greater than that thrown off by the electric lights, the area in front of the airplane which
could be illuminated by the flare extended forwa rd only about one-fourth of the di stance· of
that illuminated by the electric lights. This area , however, is entirely sa ti sfactory for land­ing
purposes.
c. Land ing made hy use of the Mark I candle in the Holt wing tip fla re bracket was not sati s­facto
ry for two reasons ; fi r st, because the pil ot was temporarily blinded by the glare from
the unshaded candle and second, because the revolving propeller hlades refl ected a disk of
light vlhich compelled him to shift bis line of vision to such an angle that a sati sfactory
landing was practically impossible. T he use of the "E-2'' bracket entirely eliminated the re­fl
ection from the propeller blades and any possi bility of the pilot being blinded by the glare
of the candle.
Altha a great number of landings were made b~, use of the new flare bracket, no malfunction
was encountered that was attributable to the flare bracket itself. Owing to the fact that the il­luminating
efficiency of the lVIark I flare candle decreases inversely as the time elapsing between
their manufacture and their use, an examination of twentv Mark I candles drawn from stock
and tested according to in structions di sclosed th1t their efficiency to be about 95% which is en­tirely
satisfacto ry for service purposes.
Several models of the T ype E -2 bracket have been tested and the device 1s now ready for
experimental 11roduction for ser vice tests.
EQUIPMENT
Celluloid Cleaning Solution (Km-C-Lac)
A small quantity of patented solution for clraning celluloid has been tested by the E n­gineering
Division recently. It was expected that t his preparat ion would prove valuable in keep­ing
windshields and cellnloid inspection windows clean and clear. It was fottnd , however, that
this cleaner. known as Km-C:-Lac. contained a gray poli shing powder, the continued use of which
would tend to scrntch the soft surface of the t ransparent celluloid used on aircraft for windshields
and in sp!':ction doors. T he use of this particular materi al cannot, therefore, be recommended to
the Sen·ice.
Liquid Oxygen Container (Bureau of Standards)
When a supply of liquid oxygen hecame available recently, the Division conducted two success­ful
flight tests with the liquid oxygen container. Mode! 1922. constructed by the Bureau of Stand­ards
some time ago. During the highest flight to an altitude of slightly over 20,000 feet, the ap-
' I '
24 T E CH N I CAL B UL LET I N No. 3 4
paratus functioned perfectly, both pilot and observer feeling normal in all respects. The operation
of this container is quite simple as it depends upon the nearly constant rate of evaporation of liquid
gas for the supply of oxygen, no regulating valve being required. When the container is half­full-
a four-hour supply for two men- it can be inverted without -any loss of liquid. At four­fifths
capacity, the supply is sufficient to last two men slightly over six hours. In this case, how­ever,
an inversion or inclined position of the container may cause a loss of liquid or greatly in­crease
the flow of oxygen momentarily, thereby causing temporary discomfort to the users but no
harmful effects.
Containers of similar design are to be constn1cted by the Engineering Division for service test
in high altitude work.
Standardized Instrument Boards.
From time to time, investigations have been undertaken by the Division to determine a stand­ard
design of instrument board for use on various standard types of airplanes. So far, no par­ticularly
satisfactory type of board has Leen adopted altho a very promising design has been sub­mitted
by the Pioneer Instrument Company in which advantage is taken of the recently developed
vertical scale instruments. By the use of these new-shaped instruments, it is possible to so re­duce
the size of the instrument board, that airplane designers and builders will be relieved of the
necessity of designing special boards for each new model of airplane. If this development proves
successful, the Air Service would be able to adopt the policy of supplying instrument boards com­plete
·with all instruments, and ready for installation. These boards would be so much smaller than
the present types that installation problems would be greatly simplified, particularly with refer­ence
to armament installations. Another advantage accrues in that the arrangement of instru­ments
would be exactly the same for all airplanes. Several each, of six different types of in­strument
boards, are to be purchased in the near future for service tests. It is anticipated that
some trouble may be experienced in regard to the ease and rapidity with which readings may be
made by the pilot.
Luminous Dial Ammeters (Weston)
One hundred luminous dial ammeters, Model 354, scale 30-0-30, purchased on Air Service
order from the Western Electrical Instrument Company have been delivered to Fairfield Air Inter­mediate
Depot, Fairfield, Ohio, for use in making up ignition switches for Liberty engines
equipped with Air Service 12-volt ignition systems haying newr Type 1-L generators. The re­modeling
of these switches is in progress.
Exide Storage Battery, Type AS-2.
An order has been placed through Chief of Air Service, Washington. with the Exide Com­pany
for 146 Type AS-2 storage batteries. These are identical to the Cincinnati AC-111, except
that Exide uses hard rubber jars in place of cellμloid. In this connection, the :use of celluloid as
a material for the jars has been abandoned, owing- to the difficulty of obtaining material that will
remain leakproof. All future batteries for the Service will he constructed with hard rubber jars.
Moore Dry Seal Storage Battery.
Tests have been in progress for some time on a patented battery known as the "Moore Dry
. Seal." This battery was claimed by the maker to be non-freezing and ,non-spillable on account
of the viscous nature of the electrolyte, and also non-gassing. The capacity of the batteries was
claimed to be about equal to the usual type built with lead plates immersed in acid-electrolyte. The
results of the tests, however, have not yet shown this capacity to be at all comparable with the Air
Service standard battery, and it is not believed that the new type will be any better than the jelly­electrolyte
batteries previously tested. None of the batteries of this type so far tested have proved
to be valuable for aircraft work.
New Electric Starter ~or Liberty (Westinghouse).
ln an effort to improve the present type of electric starter, the Vlestinghouse Company has de­livered
under an experimental purchase order, thi;ee starters for the Liberty engine. These start-·
ers contain several conunendable features and appear to be strongly made. On Prony brake test,
however, the release mechanism for overload took a permanent set and the required starting torque
could not be obtained. Developmental work on these dcyices will be continued.
AIRCR AFT DEVELOPMENT 2S
There has been a demand for some time for a gasoline level gage that could be applied to
shallow tanks of the gravity type. Recently, a complete set of drawings were obtained from the
Dayton Wright Company, illustrating a fairly satisfactory gage for this purpose. These drawings
w.ill be gone over by the Division and reissued under Air Service standards for procurement pur­poses
in case occasion arises for the use of such a gage.
"Gogglette" Goggles.
An experimental order was recently placed with E. B. l\feyrowitz, Inc., N;ew York City, for a
type of goggle known as the "Gogglette." This order was placed to try out the latest Air Service
specification. The manufacturer is having difficulty in meeting .the requirements with reference to
the tests for defects in the glass. The use of this specification for the purchase of gogglettes will
result in obtaining an article quite superior to the present goggle, many of which now in service
will be found to be defective upon close examination.
Brass Plate Goggles.
A departure from the conventional glass goggle has been instituted by the Engineering Division
in the form of a goggle using an opaque brass plate prm·idecl with narrow slits in place of the
usual glass len s. Altho much wind passed thru these slits during flight and visibility was rather
poor, it is thought that these goggles will be valuable for very high altitude work as there would
be slight chance of frost ~orming on them. Tests will be continued.
Slide Rule for Gas Computations.
Several improvements have been made on the balloon and airship lift slide rule. Earlier
models of this rule used curves of constant barometric pressure on logarithmic coordinates of
hydrogen lift and air temperature. The new model has, in addition to these lines of constant
barometric pressure, lines of constant altitude and temperature gradient lines. Data for these lines
were taken from average observed atmospheric conditions as reported by the U. S. Weather
Bureau.
A scale of decreased lift in pounds per 1,000 cubic feet at 100 per cent relative humidity is
plotted beside the temperature scale on the slider. The reverse side of the rule contains percent­ages
of initial volume for the various altitudes and ground temperatures, and a scale giving the
decrease in Yolume clue to a superheat of 1 degree Fahrenheit per 1,000 feet. This rule can be
used for either hydrogen, coal gas, or helium by shifting the slider relative to the movable scale
of per cent purity. A small catch holds these parts of the rule together while the computations are
being made.
Night Field-Marking for "T-2" Endurance Flight.
The electrical Field-marking equipment used in connec.tion with the record-makiug endurance
flight of the Air Service Transport T-2, last April, over the 50-kil<?meter triangular course from
Wilbur Wright Field to New Carrisle, Ohio, and thence to McCook Field, functioned very satis­factorily.
At McCook Field and New Carlisle pylons rotating incandescent beacons were mounted
on modified steel windmill towers, fifty feet high. In addition, a rotating, 36-inch, high intensity
searchlight was used for flood-lighting McCook Field. This light was stopped during the time that
the T-2 was passing the pylon on each lap of the course. Another 36-inch, high intensity search­light,
taking power from a Mack truck, was used at Wilhur W_right Field for flood-lighting the
pylon ( field water tower) during the few minutes that the T-2 was passing. The illuminated water
tank at McCook Field, which was described and illustrated in T echnical Bulletin No. 29 served as a
very efficient pylon and field marker on this flight. An emergency landing field at New Carlisle
was illuminated by an 18-inch incandescent searchlight equipped with a 110-voit bulb and mounted
on a Cadillac automobile chassis. Both pilots of the T-2 commented very favorably upon the ex­cellent
lighting equipment furni shed, every unit of which functioned perfectly during the entire test.
26 T E C H N I C A I. 13 U L L E T I N N o. 3 4
Portable Field Beacons.
Development of a complete portable outfit that could be used either for landing field illumi­nation,
or as a beacon has been in progress for about a year. It was found that the Engineers'
Corps had avai lable, a n11mher of 36-inch, high inten sity searchlights with automatic feed. and that
these searchlights could be operated by a generator installed on the front end of a Mack searchlight
truck. An experimental installation was then made with this equipment. T o use the searc-hlight
as a beacon, an electrically-operated revolving mechanism was developed and applied . Th.is beacon
was easily visible at night from a di stance of six ty mil es. To use the searchlight as a flood light
for landing fie ld illumination , a so-called "spread lens" was applied over the beam door, thus
changing the straight beam into a flat, fan- shaped one. \Vhen th is beam is correctly adjusted , a
long rectangular space is uniformly illuminated on the land ing field.
The fir st complete outfit for service use is just being fini shed at McCook F ield , and will be
shipped to Kelly Field. FiYe more outfits are under construction, and will be forwarded as soon as
tests are completed.
Drawings have been completed for a revolving mechani sm for nse on 36-incii , high intensity
searchlight beacon for night flying as mentioned above.
New Landing Light, Model 1923.
A nevv electric landing light for aircraft
ELECTRIC LANDING LIGHT, MODEL 1923
has been developed by the Division to supersede the
original :Model J -60. The new light known as
"!V[odel l 923," is much smaller, more compact and
of lig hter weight than the· old design. It is fitted
with a 12-volt, 35 ampere lam1) and a two-inch
focal length refl ector, which assembly gives a
candle power of 200,000. The glass door in front
of the light is curved to reduce resistance. Several
concentric blackened cylinders are placed between
the !lamp and the door to prevent any diffusion
of ,;tray iight to the side ,vhere such light might
illmninate ground haze. mist or reflect from the
r~v_olving prcpeller, thus impairing the pi lot's
VI S!On.
The light may be installed on the tip of the wing as shown in the accompanying illustration and
streamlined along the chord. ( S ce view on pa.ge22) . Sever~d sets have been received from the
manufacturer for use on several night flying projects being- conducted by the Service. T he new
light will be in stalled on the new Air Service transports "T-3" under construction b,· the L-W-F
E ngineering Company. ·
Landing Lights on NBS-1.
The correct position for Model 1923 electric landing lights on the NBS-1 night bombers has
been finally establi shed. T he decision to place these lights under the fu selage was made 01:1ly af ter
a series of niglit flights in which these lights were placed in various positions on the wings and
fuselage. The new location not only eliminates heavy wiring in the wing and large connector panels
at the wing hinge, wiing fold and tip but directs the illumination on an area that can be clearly seen
by the pilot in landing. The lights are turned slightly to left ( pilot's side) as shown on opposite
page.
Tcc!tnical instructions for temporary use have been apprm·ed and released by the Division re­garding
the equipment of service airplanes with Holt flares and landing lights for night flying.
New "K-5" Camera.
Several service cameras, Model K-1 , have been modified by the Eastman Kodak Company for
hand operati on in accordance with an experiment:i! rnodel forwarded by the Engineering Division.
The new designation, "Air Service Type K-5", appears on each camera along with the serial num­ber.
Six cameras have been completed and shipped to the Air Service Technical Schools at Ran­toul,
Ill. , and the seventh to Crissy F ield, Califo rnia.
AIRCRAFT DEVELOPMENT 27
The "K-5" camera supersedes both the "K-1" and "K-2" models, leaving only the "K-3"
type for full automatic operation. A dissected model of the latter has been received by the Division
for inspection and exhibition purposes.
Field Photographic Trucks (Revised Specifications ).
Revised specifications have been issued for two laboratory trucks that comprise part of equip­ment
for aerial photographic units for use in the field when no suitable laboratory is available m
the sphere of operations. These trucks are known as follows:
Developing Truck for Aerial Photographic Unit (A. S. Specification No. 30,014-B).
Printing Truck for Aerial Photographic U nit (A. S. Specification No. 30,013-B).
The bodies of these trucks are made from trailer bodies of French design ma.nufactured in
quanti ties by the Hopkins Manufacturing Company during the ·world War. They a:-e equipped
wi th standard lauoratory apparatus, in additicn to power-operated pumps, tent flies, etc.
One set of truck units has been placed in service for test and instructional purposes at the
. \ir Service Technical Schools at Rantoul, Ill.
POWER PLANTS
Improvement of Lawrance "J-1."
Recent development by Division to improve performance and reliability of the Lawrance
;\fodel J-1 fixed radial engine for training and li!!ht pursuit purposes, has been directed to red uc­tion
of excessiYe oil consumption and to design of an imprO\·ecl induction system.
Lubric;ition tests di sclosed that excessive oil consumption was apparently caused by too much
end clearance at master connecting rod bearing. The engine was torn clown, reassembled with
smaller clearances and balanced oil outlet line from crankshaft and tested on dynam::imeter with
resultant improvement showing an average hourly oil consumption of 2.6 lb. at full power and 1.2
lh. under 90 per cent power. A 10-hour en,lurance test will be given before engine is installed
in a DH-4B airplane for flight tests.
CORRECT POSITION OF LANDING LIGHTS ON NBS-1
28 TECH N I CAL B UL LET I N No. 3 4
The new rotary induction system designed by the Division requires only one carburetor (the
standard engine having three) , thus greatly simplifying operation. On the dynamometer, an
engine equipped with the new induction system operated satisfactorily at idling speeds as low as 90
r. p. m. Such low speeds were produced to some extent by fly-wheel action of the dynamometer
armature and probably could not be attained with propeller installed. On the whole, the engine
ran smoothly with good acceleration but failed to develop full power.
Wright Radial "R-1."
A Wright radial engine, Model R-1, has been rebuilt and calibrated preparatory to flight
testing in DH-4B airplane which has been equipped with a special engine mounting to accommodate
this air-cooled engine. On the dynamometer, the engine developed 382 h. p. at 1700 r. p. m.
Liberty, Model 1921.
T'hirty-six Model 1921 Liberty "12 A" engines are being overhauled for Air Service stores.
Another lot of forty-eight are being remodeled for flight purposes. A rumor that Model 1921
Liberty engines equipped wjth stub-tooth gears were giving trouble in service proved erroneous upon
investigation which disclosed that the engines in question were not equipped with stub-tooth gears.
So far, not a single complaint has been reported to this Division on failure of said gears.
1000-Hour Magneto Tests.
Two Scintilla magnetos have satisfactorily completed the 1000-hour endurance tests insti­tuted
by trus Division for the purpose of developing reliable magnetos for aircraft engines. No
breakdowns occurred during test of first magneto at full speed, 2400 r. p. m., and the second
finished the 1'!:est satisfactorily with exception of uneven burning of the breaker points, caused by
mis-alignment, resulting from wear at breaker pivot.
One Apollo magneto has completed a test la sting 983.5 hours.
Oil Heater for Winter Flying.'
An oil heater for winter flying has been built for installation in a DH-4B airplane for ex­perimental
test, to determine the extent to which lubricating oil can be heated without detrimental
results. These tests are being conducted in summer weather when heater must operate under
most severe conditions.
New Specification for Gasoline Hose.
At the request of Chief of Air Service, a new Air Service specification for gasoline hose has
been drawn. The new specifications will not produce as high a C!Uality of hose as the previous one
but can be more easily met by the manufacturers.
A number of objections have frequently been raised by manufacturers against the Air Service
specifications for gasoline hose. It appears that the difficulty is due not so much to meeting the
requirements of the specification as to the fact that Air Service demands are not large enough
to be financially attractive to an industry that is producing inferior grades of hose on a large scale.
\Vhen rubber is immersed in gasoline, it swells, thereby restricting the passage of fuel. Mani­festly,
it would be a very serious situation if the hose used in the airplane swelled sufficiently to
close the fuel line completely. For this reason, certain specifications must be met if satisfactory hose
is to be obtained. This fuel action on rubber differentiates the gasoline hose from the common
garden or water hose. It is possible with careful usage and frequent replacement to use a
cheaper non-specified grade of hose for this purpose and for this reason, waiver of certain stand­ards
in the new specification has been advised.
Superchargers for DH-4 Airplanes.
Twelve General Electric turbo-superchargers, Form D, are being assembled at Fairfield Air
Intermediate Depot, Fairfield, Ohio, for installation on DH-4B airplanes for service test.
RESEARCH AND EXPERIMENT
I
RESUME OF ENGINEERING DIVISION
SERIAL REPORTS.
Serial R eports marked with an asterisk (*) will
be issued by the Chief of Air S ervice as "Air
Sen 1ice I n.fonnat-i()n Circulars."
AIRPLANE SECTION
Effect of Eccentricities on Stresses in Airplane Spars. *Serial No. 2095
The object of this investigation is to illustrate and compare methods of analyzing and com­puting
effect of eccentricities in wing fi ttings on moments, shears, and stresses in ,-Ang spars.
An eccentricity is developed when two or more structural members are so joined together that
their longitudinal axes do not interesect at a common point. When eccentric stresses are induced,
the factor of safety of the structure will be lowered unless additional material is added to one or
more of the structural members affected. Experience has proved t hat the safety factor of a spar
may be reduced as much as twenty-five per cent by poor design of the wing fi ttings, hence great
care should be exercised in arrangement of structural members and in design of fittings in order
that required strength may be obtained with least possible weight.
Three methods for computation of moments, shears, and streses in spars when eccentrically
loaded are given and explained, the front spars of Vought VE-7 and E ngineering Division C0 -2
airplanes being used for example. In addition to the tables, the results are graphically presented
by use of several figures and diagrams.
Properties of Box Spars. *Serial No. 2104
Five important formulas are derived herein for facilitating computation of the moment of
inertia and the section modulus of box spars with unequal fl anges of rectangular section.
Computation of Stresses in Drag Trusses. *Serial No. 2107
The purpose of this report ·is to explain some short cuts and approximations that will be per­mitted
by the Engineering Division in computation of stresses in drag trusses and to illustrate a
simpli fied method of arranging computation of streses in parall el chord trusses in general. In
submitting computations for parallel chord drag trusses to the Division, it is suggested that airplane
designers and engineers follow model form given in report until publication of superseding in struc­tions.
Airplane Performance and Design Charts II-Fineness. Serial No. 2119
This report is sequential to Air Service Information Circular No. 183 (Vol. II ) in which "Fine­ness"
was 'introduced as a variable in predi ction of performance. and has for its obj ect the develop­ment
of a new method of closer approximation in the selection of fin eness for a proposed or un­tested
airplane by compari son with airplanes already tested.
' ·, .
30 T E C H ?\ I C . \ L I3 U L L E T l ~ N o. 3 4
Fineness has been developed as a function ofthe ,ving and parasite resistance and the smaller
the ratio of the latter or equivalent fla t -plate area, Ae, is to the former expressed in terms of RAF-IS
wing area. A. the cleaner the airplane. the higher its fineness and the better its performance. The
selection of ctn approximate value of Ac for a prop0sed airplane by comparison with known values
of Ae for airplanes in the table -of this report can be made with greater accuracy than selection hv
the old method given in the Circular.
A chart on "Fineness" as affected by various factors is appended.
Airplane Performance and Design Charts III­Airplane
with Any Aerofoil. Serial No. 2120
This report embraces the development of a method for solving per formance and design prob­lems
concerning an airplane with any power plant, wing a rea, gross weight, external characteris­tics
and in particular, equipped with wings of any profile whose lift and drag coefficients are
known from a wind tunnel test or of any profile which has been used on an airplarn: that has un­dergone
performance flight tests.
Until quite recently, nearly all airplanes used for military purposes in this country were
equipped with the RAF-15 aerofoil to which Air Sen·ice Information Circular No. 183 (Vol. II ) is
applicable but since the value of so-called thick wings w.as demonstrated by Fokker and Junker air­planes,
aernfoil!" of similar characteristics are being adopted to some extent hy American designers.
In order to meet the need for a system that can be applied uni ver sally to ~irplanes with wings of
any aerofoil -section. auxiliary charts were const ructed for expressing wing area of thick aerofoils
in terms of an equivalent area using RAF-15 aerofoil.
These charts, when used in connection with charts on "Fineness," "Performance and Design."
and "Speed-Altitude" of r~ports p:-evionsly mentioned, for "Equivalent RAF -15 Area" show how
performance of any airplane equipped with any aerofoil may be determined quickly and easily.
This method is equally valuable in predetermini1~g design for either military or commercial air­planes.
Airplane Performance and Design Charts IV-Maneuverability. Serial No. 2121
Tn thi s discussion on maneuverability of airplanes . . a method is formulated; first, for compar­ing
inherent stability of ai rplanes to maneuver; second . tu furnish a criterion for estimating prob­able
maneuverability of a proposed airplane; and th ird . to gnide the desi~·ner in . fi.xin£; funda-­rnental
characteristics of his airplane so as to olY:ain the best compromise in performance.
Manenyerability is arbitrari ly defined as the i1~herent ability of an .airplane to execute climb­ing
turns of small radii; 'that is, the ability to gain altitude in a tight spirai. Inherent abili ty may
be defined as depending only on the fundamental cha racteristics of the airplane--weight, horse­power,
area. wing profile. ,rnd parasite resistance,- exclnsiYe uf the control surface design. effec­tivene5s
or ease of operation. T he Yariati(m of horsepower with altitude. is considered to be the
same for all power plants. and the representati Ye loss of power with altitude as determined em­pirically
for the Liberty " 12" engine-propeller group. is used. This greatly simplifies the solution
and is not inimical to good comparati,·e results. A further simplification results from introducing
"Fineness" as a measure of the efficiency of the profile and as a correction to the horsepower
available. using the DH-4 model test results as a basis.
A complete understanding- of these assumptions can only he obtained by reading the three
reports on ·' .\ irplane Performance and Design Charts" already published. The mathematical solu­tion
for minimum radius of horizontal turn at constant speed is developed and a graph for quick
solution is constructed. Inherent ability to maneuver is measured by the ratio R/r, where "R" is
the rate of climb without turning, obtained from flight test results, and "r" is the minimum
radius in a turn without climbing, obtained by the method of this report. A proposed method for
classification of ai rplanes is a lso included in the present report.
Ferrule Ends for Streamline Wire. *Serial No. 2125
An attempt has heen made to develop a method of usmg uncut st reamline wire with ferrt1le
ends, loop bends, and so lder for repairs in the fieid or in experimental installations where it is
often out of the question to wait for manufacture of streamline wire with threaded end s. cut to
correct length.
RESE A RCH AND EXPERIMENT 31
The report gives an account of preliminary tension tests of specimens embodying this idea in­cluding
a description and views of the terminal, a table of dimensions of parts for use with each
size rod, and tabulation of results obtained. The possibility of using this joint with present stand­ard
aircraft fittings is limited for the present to two smalier sizes, No. 6-4-0 and No. 10-32, wider
fitting~ being required for the larger rods.
Nomographic Column Charts. *Serial No. 2128
(Su persedes Serial No. 1700-A. S. I. C .. No . 304 .)
The following eight monographic charts to aid designers 111 design of wood, steel, or dura­lumin
columns conform, with one exception, to latest Air Service standards for tnbe sizes and
specificati9ns for material and, therefore, super sede those charts publi shed in Air Service In­formation
Circular No. 304.
The new charts are as follows:
Wood
Steel
MATERIAL
Spec. 10225
Spec. 10226
Spec. 10227
Duralumin
SHORT COLUMNS
Johnson's Formula­Square
Spruce Struts
John son's Formula
Yield Point 36,000 lb/sq. in.
" " 60,000 "
105,000 "
125,000
Straight Line Formula
47 ,000--( K) L/p
Duralumin Spar for Engineering Division TA 4 Airplan~.
LONG COLUMNS
E uier's F ormula­Streamline
Struts
Euler's Formula
E = 28,000,000
E = 28,000,000
E = 29.000,000
E = 29,000,000
Euler's Formula
Use Euler Steel Chart
E= 29;000,000 and divide
allowable load by 3.
Serial No. 2135
A static test was made on an experimental spar made of duralnmin tubing, with exception of
one wrapped steel fitting, for use on a proposed training type airplane. T his project has since been
abandoned.
ARMAMENT SECTION.
Gun Sight, Type X-6. Serial No. 2106
Report gives views. description, and operation of ·a new gun sight, Type X-6, for use on
flex ibly-mounted machine guns to com!wnsate for the speeds of both the attaching and the attacked
airplanes. The sight is based on the Reille-Soult Sight used by the French during the late war.
The sighting principle as applied by the F rench, required setting the correction for both speeds
while on the ground. An attempt we>. <; made in the present inn:stigation to incorporate an adjust­ment
to compensate for enemy speeds while in flight without use of tools but this proved im­practicable.
Complete in structions for installati on and diagrams illustrating the operation of the
sight are included.
Flexible Browning Floor Mount. Serial No. 2108
A floor mount for flexibly mounting a .30 caliber Browning aircraft machine gun beneath the
iuselage of an airplane for protection of area below tail sur faces was built and tested on ground
and in air with satisfactory results. The mount consists of a Type A ring mount suspended in
reversed position under i nselage of a DH-4 airplane in such a manner as to bring the butt of the
gun jnst back of flooring in rear cockpit. A ]eve:- was ;:ittached to Spade grip of the gun to facili­tate
manipulation of the mount.
Altha the device functioned satisfactorilv, no immediate use of mechani sm is advocated at
present due to the fact that the Browning gtin has not been accepted for flex ible use in the Air
Service.
. "
32 TECHNICAL BULLET IN No. 34
EQUIPMENT SECTION.
"T-1" Transforming Camera, Model 1923. · SerialNo. 2102
Complete instructions supplemented with illustrations are given in this serial for care and use
of the "T-1" transforming camera and accessories, Model 1923. This transforming camera is
used to make photograpbs from oblique negatives taken with Air Service Model T-1 camera (Bag­ley
Tri-Lens Camera), each transforming camera being adjusted, when made, for use with a par­ticular
T-1 camera. Both cameras hear the same serial number and must he used in connection
with each other. The instructions are specific particularly in regard to developing and printing of
film and paper.
Test of Precimo Gyro Inclinometer. Serial No. 2114
The Precimo gyro inclinometer is an in strument of French design for indicating to the pilot
angle of bank or angle of ascent or descent of the aircraft in flight. It likewise indicates level flight
due to the fact that both lateral and longitudinal angles are indicated on a common dial, therefore
having a common zero position.
The results of the tests conducted by the Division both in flight and in · the wind tunnel
demonstrated that this mechani sm is not reliable and would not be of any service in "avigating"
aircraft.
FLYING SECTION.
Airplane Flowmeter Installation. Serial No. 2144
Oscillations in the Schroeder flowmeter, an aircraft in strument for measuring fuel comsurnp­tion,
have been eliminated by means of a surge tank inserted between the carburetor and the in stru­ment.
This tank serves to dampen the· pulsations in the system, thus permitting the flowmeter to
he read with accuracy in connection with fuel economy tests.
The development carried on in this investigation is preliminary to a general report on eco-
- nomical flight now in preparation. The apparatus used in the tests is very complev and is used
only for experiment purposes in securi_ng data 011 economical operating speeds of a few service air­planes.
A description of the flowmeter will be found in Report No. 129, "Power Plant Instru­ments"
by National Advisory Committee for Aeronautics and in Report on "Test of Schroeder
Flowmeter, Type "C," No. 1," by E ngineering Division.
Schematic layout of fuel system and views of in stallation are given.
PERFORMANCE TESTS.
The following performance tests have been completed by the Engineering Division. The
standard report includ~s a summary of results, weight schedul e, performance graphs, brief descrip­tion
and views of airplane, description of power plant, ·and pilot's observations.
Loening PW-2B. *Serial No. 2024
This is an experimental A. S. Type I pursuit airplane, equipped with high compression
Packard "1237" engine, built by Loening Aeronautical Corporation of New York. Description
and views were published in Technical Bulletin No. 28.
Loening PW-2 (Experimental Model). Serial No. 2025
This airplane is an experimental A. S . Type I pursuit model similar to Loening P\V-2B in
general characteristics with exception of power plant, which is the vVright 300-h. p. engine, and
the vertical tail post.
RESEARCH AN D EXPE RIM ENT
Loening PW-2 (Experimental Model).
33
*Serial No. 2026
This airplane is same as Model PVv-2 in Serial No. 2025 except that center section oi wing
is cut away giving in creased performance. Views and descripti on are given in Technical Bulletin
No. 28 . .
Dayton-Wright TA-3 with 110-h. p. Le Rhone Engine. *Serial No. 2101
The "TA-3" is a side-by-side two-seater training airplane built by Dayton-vVright Company
for Engineering Division. This model is equipped with a 110-h. p . Le Rhone rotary engine which
makes it a better airplane for primary training and cross-country . fl ying than the earlier model of
the same type equipped with 80-h. p. Le Rhone engine.
Huff-Daland TA-6. ~'Serial No. 2157
·. i'
This is a Type XIV biplace airplane built by firm of Huff-Daiand and Company' for ad-vanced
training. It is powered by a new Law.ranee "J-1" 200-h. p. engine and gives a very promis­ing
performance.
Dayton-Wright TA-5. *Serial No. 2158
This is a two-seater tra1111ng airplane similar in design to the Dayton-\Vright TA-3 except
that it is equipped with the new Lawrance "J-1" radial engme. The seating arrangement has im­portant
adnntages for side-by-side in struction.
LIGHTER-THAN-AIR SECTION.
Speed and Ceiling of U. S. Army Airships. *Serial No. 2161
The purpose of this investigation is two-fold; fi r st. to point out theoretically the precise man­ner
in whi ch high speed and high altitude, terms antith etica!ly related with reference to air ship
performance, are generally applicable to all types and classes of airships and in particular to the
principle tvpes of airshi ps operated by or under construction for the U. S. Army ; second , to
determine by calculation the maximum possible altitude or ceiling of various Army air ships with
hydrogen and helium. of differ ent purities and with mixtnre of these gases. based on ratio of " fi xed
load" to "total lift."
MATERIAL SECTION.
Chrome-Vanadium Steel (6120). *Serial No. 2109
The effect of drawing temperature, thickness of sheet, di rection of rolling, and quenching
medium on the proportional limit, tensile strength. elongation. and bending quality of low carbon
chrome-vanadium sheet steel, together with that of brazing at 1750c and 1900° F . 0 11 these proper­ties,
was determined as follows :
a. Tlic physicai properties are marked!? affected by the carbon and chromium content, the best
results being obtained with steel having carbon content greater than 0.18 per cent and a
chromium content greater than 1 per cent.
b. Heat treatment resulted in increase in tensi le strength with decrease in drawing tempera­ture
and increase of proportional limit with decrease in drawing temperature up to 800° F.
after which it decreases with lower drawing temperatures. Ductility as measured by elon­gation
and bend tests, decreases with decrease in drawing temperature.
c. Physical properties are not affected by relation between the axis of the test specimen and
direction of rolling. Thickness of sheet affects elongation ratio.
d. Water quenching gives higher proportional limits and tensile strengths than oil quench­ing.
The effect on other properties being negligible.
o?. Brazing experiments indicate that certain mixture will act as a heat-treating medium with
result ant higher tensi le strength.
34 T E C H N I C A L B U L L E T I N N o. 3 4
Manila Hemp Rope. *Serial No. 2123
Owing to difficulty of obtaining Italian hemp in quantities sufficient for emergency, it became
necessary for the Division to develop a Manila rope 'whose physical properties would be com­measurable
with those of Italian hemp rope which in small sizes from Ys to :}';i -inch in diameter
is generally used for halloon rigging by virture of its high tensile strength with low weight and
its flexibility and ease of handling in manufacture of balloon nets.
Experimentation has successfully produced a Manila rope of tensile strength and weight per
unit length equal to that for corresponding sizes of Italian hemp rope, by changes in construction
of the strand and in structure of finished rope. A further improvement in physical properties and
appearance of experimental Manila rope can also be attained by use of higher quality fibre by
changing material from A. S. Specification Grade I to Gracie D or E .
Chrome-Molybdenum Steel Tubing. *Serial No. 2129
An investigation of variation in physical characteristics of three sizes of chrome-molybdenum
steel tubing after quenching and drawing disclosed that tensile strength and proportional limit of
quenched tubing varied inversely with drawing temperature whereas ductility varied directly with
drawing temperature. At 600° F .. however, proportional limit decreased with decrease in draw­ing
temperature, a characteristic of alloy steels. Water qm:nchiug produced greater tensile strength
and higher prnportional limit than oil quenching on the smaller sizes which developed greater tensile
strength than crushing strength.
Aluminum Ingot. *Serial No. 2132
This is a study of metallographic characteristics of commercially-pure aluminum with par­ticular
reference to occurrence of iron and silicon when such impurities occur either as unavoid­able
impurities or in added amounts up to 4 per cent each.
A summary of important characteristics of three grades of commercial ingot aluminum and
the effects of copper, iron, and silicon in varying amount.:; and combinations are given together
with micrographs of structures, and photographs of specimens and casting molds.
POWER PLANT SECTION.
Cockpit Heater for Altitude Flying. Serial No. 2035
At altitudes above 20,000 feet it is difficult to keep warm even under most' favorable condi­tions
as has been demonstrated on early high altitudes flights of LePere supercharged airplane in
which Major Schroeder and Lieutenant E lsey (McCook pilots) suffered severely from cold. In
Lieutenant Macready's World's record altitude flight to 40,800 feet (indicated), the pipe from
water header to radiator was passed thru cockpit, thus supplying small amount of heat. Recently, a
small hot water radiator, 15 inches widt by 2 inches thick, built of standard 9-inch core tubes was
placed in cockpit and connected in water line between expansion tank and radiator ; a by-pass and
control valve being provided to regulate the heat.
Oxygen System for Supercharged Airplanes. Serial No. 2036
In order to test supercharged airplanes at high altitudes, an oxygen system was needed that
would furnish an adequate supply of oxygen under all conditions. Inasmuch as automatic systems
have not yet proved suff iciently reliable, a manually-operated system was built consisting of four
units shown herewith as follows :-oxygen bottles, reducing valve, heating coil, and supply tubes.
The oxygen passes from the bottles to .the reducing valve thru Ys -inch brass tubing with
silver soldered connections, thence from valve by 74-inch copper tube thru heating coil in radiator
expansion tank where gas is warmed before reaching pi lot and observer thru the flexible tubes.
RESEARCH AND EXPERIMENT 35
At start of a flight, the airplane crew chief opens the valves on the oxygen bottles, allowing
{WI@ a11c 11t1!fc
liflllTd,!' OM!TSIO!T
lil:1A:
gas to flow to reducing valve where its pressure
RE6tl&Tlll5 lli!'Yc O/!ie/1Tct7 is indicated on a small gage. For a full bottle.
BY Tlfc l"/lOT.
'f"tEl!&.c 7tlt!c5 Td
rRO!TT R/10 ,.ee',9,e
C0::-1(1'/T~.
MANUALLY-OPERATED OXYGEN SYSTEM.
Carburetor Test Chamber.
this pressure -is about 1800 lb. per sq. in. and
bottles should be replaced when pressure falls be­low
350 lb. per sq. in. When altitude is reached
which requires use of oxygen, the pilot gradually
opens redticing valve until sufficient supply of oxy­gen
is obtained for himself and observer, the gas
being "smoked" thru a mouthpiece on the flexible
tubes.
It is hoped that the manual system will be dis­placed
by an automatic system that will require
no attention on part of pilot. Such a .system has
much to recommend it.
Serial No. 2072
Report gives description and views of the carburetor test chamber designed and built by En­gineering
Division for use in dynamometer laboratories at McCook Field. This apparatus is used
for obtaining information regarding metering characteristics, that is, ratio of mixture and flow of
fuel, of carburetors for aircraft engines under various conditions of temperature, air flow, throttle
opening, and altitude (density) before such carburetors are put into flight test and, in addition, for
obtaining specific information on carburetors that do not function satisfactorily in service or on
which some design changes are contemplated. Methods for making tests are discussed also.
. Two test chambers of similar design are already in use; one at U. S. Bureau of Standards,
Washington, D. C., described in Report No. 49 by National Advisory Comniittee for Aeronautics
and the other at factory of the Stromberg Motor Devices Company, Chicago.
Elect of Exhaust Back Pressure on Power. Serial No. 2148
On basis of this test, the power loss caused by back pressure from exhaust on an engine
equipped with turbo-supercharger should not exceed 3 per cent. A curve by which power of a
supercharged engine can be estimated is appended.
INVESTIGATION OF MATERIALS
New Coating for Aluminum.
A recent inwstigation completed by the Engineering Division resulted in the discovery of a
coating for aluminum that will resist corrosion from salt spray, water, gasoline, or atmospheric
conditions. This coating consists of sodium silicate of specific gravity 1.1 applied to the parts
either with brush or by dipping after which the parts are then baked for about two hours at 250° F.
The process is comparatively simple and can be performed by any manufacturing establishment
equipped for baking varnish or enamel coatings. Application of this coating to gasoline tanks and
carburetors should prevent eorrosion from water which has on several occasions caused serious
failures in functioning of fuel system. The new treatment of parts has given very satisfactory re-sults
on both cast and sheet aluminum and its alloys. ·
Bearing Metals.
A recent examination of wrist pin bushings from the Bristol Jupiter engine ( British manu-facture)
intlicates that a phosphor bronze of the following composition was used :
Copper ........................................ 68 per cent
Tin ........................................... 8 per cent
Phosphorus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3 per cent
36 T E C H N I C A L B U L L E T I N N o. 3 4
So far as it is known, this composition has never been used in this country for bushings in
aircraft engines. It is harder and has better wearing proper.ties than the gun metal which is used
in Liberty engine bushings, but is more brittle. The Rockwell hardness ( with Ys inch ball) of
the phosphor bronze is 57 whereas that of the standard gun metal is only 35.
Another bearing metal tested was the graphitized bearing bronze which bas recently been per­fected
by the General Motors Research Corporation. The chemical analysis of this metal showed
copper, 83 ; tin, 10; carbon, 4.7; iron, 0.6, which composition is very similar to the General Electric
Company's material known as "Generalite." The graphiti ze.d bearing bronze is recommended for
use as an oilless metal.
Drilling Properties of Brass and Bronze.
An investigation was completed on the drilling properties of several brasses and bron zes in
order. to determine the material which would give a clean, burrless hole when drilled with 1/ 16 and
1/ 32-inch drills. The best material was found to l•e extruded aluminum bronze heat-treated by
quenching in brine from 1600° F. Red brass, Air Service Specification No. 11 ,026, was the best
non-ferrous alioy for this purpose.
Bronze Ingot.
The E ngineering Division has made a general practice of testing metals from various sources
of supply in ord er to determine what sources can satisfactorily meet the requirements of Air
Service specifications. Anchor Brand manganese bronze from the Great vVestern Smelting and
Refi ning Company under A. S . Specification No. 11 ,021 was recently tested, specimens being taken
from the ingot which was then melted down and new specimens cast in accordance with our stand­ard
method. All test specimens passed the requirements of the specification and had the follow­ing
physical properties:
Tensile strength, lb/sq. in . ... . ....... ..... ......... ..... .
Yield point, lb/sq. in ....................... .. . : .. . ...... .
Elongation in 2 in ., per cent .. . ......... ... . ... . . . . ....... .
Brinell ( 500 kg. ) . .... .... · . ...... ... ... ..... ... .. ...... .
71 ,000
33,000
37
121
The superstrength bronzes are special types of the copper-zinc alloys which have tensile
strengths of about 100,000 pounds per square inch. Bronze tested by this Division was received
from the ·William Cramp & Son. Ship and Engine Building Company, Philadelphia. The chemical
composition was found to be as follows: copper, 64; iron , 2.82 ; aluminum, 5.24; manganese, 3.13;
zinc, 24. The physical properties of the test specimens cast in our foundry were as follows:
Tensile strength, lb/sq. in.. .. ..... ..... ... .. ..... .. ....... 115,000
Yield point, lb/ sq. in. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93,000
Elongation in 2 ,in., per cent. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.5
Brinell hardness ( 3000 kg.) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
The super strength bronze compares favorably with the H y-Ten-Sl bronzes made by the American
l\fanganese 'Bronze Company. Tests by the Division on the latter showed a tensile strength of
110,000 pounds, with an elongation of 14.5 per cent. The composition of this material was cop­per,
66 ; iron, 2.5; aluminum, 6; manganese, 2.5; zinc, 22.5.
Proposed Standard for Chrome-Vanadium SteeL
In April, a meeting of the Chrome-Vanadium Steel Committee of the Iron and Steel Division
of the Society of Automotive Engineers was held at the Engineering Division. Data prepared by
this Division were compared with data obtained by several steel manufacturers and consumers, and
~entative curves decided upon for presentation to the Society of Automotive Engineers in estab­)
ishing standard physical properties for this material.
Balsa Wood in Aircraft Construction.
A short investigation of Balsa wood was corr.pletecl by the Division and the results, compared
directly with those obtained on spruce under the same conditions, indicate that Balsa wood with an
oven-cir:-· weight of 8.3 pounds ·will have strength properties approximately 18 to 27 per cent. of
those for good spruce.
RESEA R CH AND EXPERIMENT
COMPARISON OF BALSA AND SPRUCE ON ACTUAL T.TN IT FIBER STRESS IN BENDING.
Species
Balsa . . . . . .
Spruce .. . . .
Oven-dry
Weight
lb/ cu. ft.
8.3
26.
Fiber Stress at
Elastic Limit,
lb/sq. in.
2,000
8,000
Modulus of Elasticity
10\JO lb. per sq. in.
375.5
1683
37
E.L.
Weight
241
308
Tests brve been completed on wing ribs made of balsa wood. These ribs were designed by the
Division for the new Amlmlance airplane. Model A-1, and consist of balsa wood cores with birch
and spruce plies on the outside. It was found that considerable reinforcement w;as necessary on
the diagonal tension members in order to give a loadweight ratio of 45. T he construction looks
promising, however, and an allotment has been requested by the Division for further development.
A representative of the Engineering Division is visiting several Air Service depots for in spec­tion
of wooden parts and general storage conditions for such. Airplane parts such as struts.
wing and ai leron beams, longerons, or other wooden members, that were found defective were dis­carded.
The storage conditions were reported a~ being excellent and all plywood in good condi­tion,
only slight deterioration of glue having taken place. Air depots at Fairfield, Ohio, and Little
Rock, Arkansas, were among those visited.
NEW BOOKS AND DOCUMENTS
REFERENCE DATA ON AERONAUTICAL DEVELOPMENT
AND ENGINEERING IN THE l.'NITED STATES AND
OTHER COUNTRIES ADDED TO THE TECHNICAL FILES
OF THE ENGINEERING DIVI SION, AIR SERVICE.
AVIATION AND AEROSTATION.
GREAT BRITAIN.
British standard glossary of aeronautical
terms. British Engineering Standards As­sociation.
Jan., 1923. 123 p. diags.
Government financial assistance to civil a ir
transport companies. Air Ministry. Civil
Air Transport Subsidies Committee. Feb.
15, 1923. 18 p.
Air estimates for 1123-24. Memorandum
by Secretary of State for air relating to air
estimates. M. I. D. Eng land. Mar. 5, 1 n3.
93 p.
Aerial display of Roval Air Force in Con­stantinople.
M. I. D. Turkey. Mar. 7, 1923.
3 p.
Royal Air Force in Iraq. M. I. D. Eng­land.
Apr. 10, 1923. 22 p.
Contents :
1. Royal Air force placed in c harge
of police work in Iraq.
2. Troops in Iraq.
3. Scheme of defense.
4. Born bing operations.
6. Overhaul and repair depots.
5. Equipment used in Iraq.
7. Overhaul and repair depots .
7. Effect of desert heat on equip­ment.
8. Morale of troops in Iraq.
Improvements relating to smoke, lnn1in­ous.
or other visible trails from aircraft.
British patent specification No. 191,420. Jan.
12, 1923. 4 p. Drawings.
Air travel with s pecial referer.ce to heli­copter;
bv Maj. F. M. Green. Royal Aero­nautical
Society. Mar. 1, 1923. 3 p.
How subsidy is applied to France, Great
Britain, and Belgium. Dec. 28, 1922. 2 p.
D61.2/38
A00.3/27
A00.3 /29
Al0/16
Great
Britain
Al0/16
Great Britain
Cll.2/18
Al0.22/27
A00.3/25
Airplane reliability; by H enri Bouchi &
Louis Breguet. In French. n. d. 12 p.
The scope of airplanes; by Louis Breguet.
In French. From Aerophile, Apr. l, 1908.
6 p.
Commercial airplanes and seaplanes of
future. Will thev be monopla neg or of mul­t
iplane type? Have thick ·or thin wings?
by Louis Breguet. In French. Nov., 1921.
5 p. drawings.
Address of president of chamber of aero­nautical
industries. In French. June 22,
1922. 6 p.
Official figures for new speed records for
one kilometer made by Sadie Licointe on
Nieuport Delage sesquiplane. M. I. D.
France. Feb. 20, 1923. 2 p.
Speed records made by French, Mar. 30,
1923 for 500 and 1000 k ilometers . M . I. D.
D. France. Apr. 6, 1923. 1 p.
Report on Deutsch de la Meuthe cup race
of 1922. M. I. D. France. Oct. 6, 1922.
4 p . Photog raphs.
Comments on French aeronautical show
held at P aris from Dec. 15, 1~22 to Jan. 2,
1923. 0. N. I. 906. Jan. 5, 1923. 10 p.
Safety factors in aviation; by Louis Bleriot.
From L' Aerophile. Oct. 1-1 5, 1922. National
Adviso ry Committee for Aeronautics. Tech­nical
Memorandum No. 197. Apr., 1~23. 6 p.
Financial aspect of commercial aviation in
France; by Pierre Flan din. Comments on
same. M. I. D. France. Mar. 21, 1923.
10 p.
My experiments with helicopter; by
Etienne Oemichen. Tr. from L'Air. M. I.
D. France. Feb. 5, 1923. 6 p.
GERMANY
D52.1 / 124
D52.1/125
D52.1 / 127
A00/26
C71 .61 /23
C71.61 /28
D52.0 3/61
A00.7 /9
D52.l /129
Al0.01 /6
France
Al0.22/1
Oemichen­Peugeot
CZECHO-SLOV AKIA.
Preliminary report on congress on inter- A00.5 /28
Program of fir~t meeting of Aeronautical D60 /3
national aviation legis lation held at Prague.
Czecho-Slovakia, Sept. 25, 1922; by Maj. W.
J. Davis. M. I. D. Germany. Oct. 10, 1922.
4 p.
DENMARK.
Data on military, naval, governm ental, Al0/1
civilian, and commercial aeronautics in Den- Denmark
mark during 1922, in reply to aeronatuical
questionnaire. M. I. D. Germany. Mar.
24, 1923 . 5 p.
FRANCE.
Brief survey of aeronautical industry of F35 /48
France. M. I. D . France. Feb. 8, 1923. 43
p. Photographs.
Registered civil airplanes in France, Dec. B00.6 / 4
31, 1122, giving name of airplane and num-ber
registered. France. Jan. 29, 1923. 2 p.
The future of aviation by Louis Beguet . Al0/192
First International Congress for Aerial
Navigation. In French. Nov. 16, 1921. 15
p.
International of Zurich. In French. n. d.
10 p.
Report on safetv provision& ,for airplanes; D52.l/119
by E . Evering. Tr. from Der Motorwagon.
No. 27, Vol. 25, Sept. 30, 1922. 18 p.
HOLLAND
Civ il aviation in Holland. n. d. 13 p . Al0.01/1
Holland
ITALY
Proceedings of Italian association of aero- D00.12/183
nautics. In Ita lian. Vol. 3, No. 1. 192:l.
90 p. Charts.
Contents:
1. Recent flight successes .
2. Airplane struts.
3. Ael'ial r.avigation law£ in Italy.
LL Induction in wind tunnels of rec­tangular
s hape.
Italy to participate in aeronautical expo- AOO. 7 /7
s ition of Gottenberg, Sweden. M. I. D. Italy.
Mar. 26, 1923. 1 p.
NEW BOOKS AND DOCUMENTS
in aeronaut ica l competitions to
d In Italy during the calendar year,
JI. L D. Italy. Mar. 5, 1923. 1 p .
and reg ulations regarding Jacques
which took place at
Aq. 10 and 12, 1922, under the
n. d. 1_2 p.
comm ercial aerial
M. I. D. Japan.
Oil military, naval, governmental,
and commercial aeronautics in Nor-
1922, in answer to aernautical
• M. I. D. Germany. Mar. 26,
M. I. D. Feb. 24, 192 3.
Tr.
for United
Japan,
Russia
report on Air Service work in
with Army and Navy, Forest
Laboratory. Mar., 1923.
Feb.,
of aeronautical events during
tics, weights, and performances
Nl'riee a irplanes, U. S. Navy service
aperimental airplanes, single and
bombers, aircraft under cou­Ud
obsolete types. Navy Dept.
Aeronautics. aJn. l, 1922.
ad chemical tests on commercial
et United States; by D. W. Kessler.
of Standards . Technolog ic Papers
• Inly 15, ml 9. 5 p . Photographs.
INSTRUCTION
ENGINEERING SCHOOL.
organization for use in Army
Course A. Sub-
Plants. Air
1923. 46 p.
D52.03 /61
D 52.03 /59
Al0/11
France
Al0.01/5
France
Cl l /11
A81/15
A00/44
Al0/1
Sweden
A00.7 /8
A00.3 /28
A00.3 /26
D00.12/9~
D00.12/181
1923-Feb.
Al0/4
United
States
D00.12/9
1923-No. 23
D52.15/58
ln3-Jan.
Dll /9
C50.09 /4
C!'>3.231 / 6
C53.231 /4
Aircraft Power Plant References. Air
Service Engineering School. Apr., 1923.
Large r eport.
Pamphlet on instructions to wood worker~.
Air Service Engineering School. McCook
Field. D21-22. 32 p. Drawings.
Cooling System Problems. Course I ; by
Lt. B. Johnson. Air Service Eng ineering
School. McCook Field. March, 1923. 3 p.
Course in Electricity. Air Service En­gineering
Sc hool. McCook Field. 1923. 3 p.
Course in Aerial Phot ography. Air Service
Engineering Sc h ool. 1923. 9. p. Photo-graphs.
·
.General Aeronautical Engineering Pro­peller
Des ign. Course I. Air Service En­gineering
School. McCook Field. Mar, 1923.
41 p. Drawings, photographs, c harts.
Course of Instruction
Air Service Engineering
Field. Apr., 1923. 16
charts, diags .
on Synchronizers.
School. McCook
p. Photographs,
Course in Thermodynamics ; by C. P. Mc­Laugh
lin. Air Service Engineering School.
McCook Field. 1921 -22. 6 p.
THE GENERAL SERVICE SCHOOLS.
Course in Tactical Principles and Dis­~
ussions. R.::tids. General Service Schools.
School of The Line. 1919-20. 21 p . Maps.
Message Center; by Capt. 0. S . Albright
and Capt. C. L. Eastman. The General
General Service Schools. 1920. 19 p .
Duties of Division Machine Gun Officer;
by Capt. W. C. Short. The General Service
Schools. School of The Line. 1919-20. 45
p. Map, chart.
ITALIAN SCHOOL.
Course in Aeronautical Construction. M.
I. D. Feb. 6, 1923. 1 p .
RESEARCH
AERODYNAMICS.
Aerod}1namic efficiency of aircraft and
price of aerial transports. In French. Apr.
6 1222. 10 p.
The increase in dimensions of airplanes,
weig h t, area and loading of wings; by E.
Everling. Tr. from Technisch e Berichte.
Vol. I II. Part 2. National Advisory Com­mittee
for Aeronautics . Technical Notes No.
132. March, 1923. 27 p. Charts.
Report of I talian Aeronautical Experi­mental
Ins titute. In Italian w ith trans lation.
Dec. 15, 1 n2. M. I. D. Italy. 31 p. Diags.
Contents:
1. Interp.retation of hydrodynamic
experiments for determination of
characteris tics of '"take_off" of
seaplanes ; by C. Verduzio.
2. Calculations of equilibrium and
s tability by Rota.
3. Best position for variable loads
from point of view of equilibrium
and longiudinal stab ility; by Rota.
Report of Aerodynamical Institute at
Technical High School at Aachen. In Ger­m
an. 1922. 2 vol.
Contents :
Vol. 1 -1. Regarding laminar and e ddying
friction.
Vol. 1 - 2. Approximate integration of dif-ferential
equation of border
s tratiem.
Vol. 1 - 3. Heat transmission on eddying
fluid or gas current.
Vol. 1 - 4. Underground water currents in
s loping region s with catch basins.
Vol. 2 -1. Problems of s lotted aerofoil.
Vol. 2-2. Flight and tail spin curves.
Vol. 2 - 3. Mechanical models for sai1ing
flight.
Vol. 2-4. Influence of wind on transport
capacity.
Vol. 2 - 5. Theoretical remarks rE>garding
helicopters .
AIR FORCES, MEASUREMENTS, ETC.
Air forces and moments for B. S .-1 flying
boat with TS wings. Navy Yard. Con­s
truction Dept. Report No. 21 8. Mar. 20,
1923. 11 p . Photog raph, charts, drawings.
39
C53.231/5
Dl 1.1 /70
D52.414/122
A20 /27
A30.2/34
D52.43 /390
D52.42 /56
D52.41 / 100
C71.8/8
C50.09 /5
C53.233 /10
C51.1 /22
D52.1 / 126
D52.1/122
D00.12/117
1922
2A-No. 4
D00.12/112
D52.6/2
BS-1
40 T E C H N I C A L B U L L E T I N N o. 3 4
Air force and moments for Marine ex­peditionary
biplane; by A. F . Zahm and
others. Navy yard. Cons truction Dept. Re­port
No. 214. Feb. 17, 1923. 21 p. Pho­tograph,
charts, drawings.
Air force and moments for TS-1 seaplane.
Navy Yard. Construction Dept. R eport No.
217. Mar. 15, 1923. 17 p. Photographs,
charts, drawings.
Air force and moment for Wragg com­pound
wing. Navy Yard. Cons truction Dept.
Report No. 212. January 15, 1923. 7 p.
Photographs, drawings.. charts.
Air force and moment for \VA a irolane.
Navy Yard. Cons truction Dept. Repoi=t No.
216. Mar. 9, 1923. 13 p. Photograph,
c harts , drawings.
Air res istance 'of experimental target
s leeves: by L. H. Crook. Navy Yard. Con­struction
Dept. Report No. 213. Jan. 25,
1923. 2 p. Chart.
A tmospheric waves and their use in glid_
ing flight; by M. Albert M. I. D. France.
Mar. 28, 1923. 4 p .
Atmospheric waves and their utilization in
soaring flight; by Alber t Baldit. National
Advisory Committee for Aeronautics. Tech­nical
Memorandum No. 194. Mar., 1923.
5 p.
Determination of rotary derivat iv e s ; by
E. F . Relf and others. Aeronautical Re­:::
earch Committee. Reports and Memoranda
No. 809. (Ae. 61). T. 1628. Sept., 1921.
16 p. Charts, diags.
Determination of rotary de1+vatives ; b y
B. F. Reff and othe r s . Appendix on Approxi ­mate
formulae for rotary derivatives ; by H.
Gallaudet. Aeronautical Research Commit­tee.
Reports and memoranda. No. 809.
(Ae. 61). T. 1628. Sept., 1921. 16 p.
Charts.
Report on work being done at Bureau of
Standards on wave-length measurements in
arc spectra of gadolinium and dysprosium,
further tests of radiometers and some
measurements of planetary radiation, etc.
April 7, 1923. 15 p.
Device for taking in ballast for airships.
British patent specification No. 191,411. Jan.
11, 1923. 3 p. Drawings.
Anp1ving vortex theory to aerodynamics
of lifting surfaces; by M. Toussaint; tr.
from L'Aerophile, Jan. 1-15, 1923. Technical
Data Memo. No. 60. McCook Field. May
2, 1923. 12 p. Charts.
Investigation
E. C. Bingham.
tific paper No.
Illus., charts.
of Jaws of plastic flow; by
Bureau of Standards. Scien-
278. June 5, 1916. 45 p.
On thc> decay of vortica1 motion in vis cious
fluid; by Kwan-ichi Terazawa. Report of
Aeronautical Research Institu'te, Tokio Im­perial
University. Vo1. l , No. 4 . Nov.,
1922. 49 p. Charts.
Complete study of longitudinal oscillation
of VE-7 airplane: by F . H. Norton. Na­tional
Advisory Committee for Aeronautics.
Report No. 162. 5 p. Illus., charts.
Function and construction of new air ve­locity
calculator; by Toyotara Su hara. Re­port
of Aeronautical Res ea rch Ins titut e,
Tokio Imperial University. Vol. 1, No. 2.
June, 1922. 7 p. Charts, diag.
On new means of ascertaining mean pres­sure
in heat engine. H. E. Wimperis . Aero­nautical
Research Committee. Reports and
Memoranda No. 803. (E. 4). I. C. E . 366.
June, 1922. 10 p. Illus., diags.
Calibration of valve gear. Res earch Sec-tion.
Naval Aircraft Factory. Dec. 26,
1922. 1 p.
DESIGN AND STRUCTURES.
Airplane design; by H . P. Folland. Minutes
of proceeding s No. 3. Ins t it ution of Aero­nautical
Engineers. Mar. 31, 1922. 31 p.
Illus.
Method of direct design of framed struc­tures
ha Ying redundant bracing; by A. J.
S. Pippard. Aeronautical Research Com­mittee.
Reports and Memoranda No. 793.
(Ae. 50) T. 1714. May, 1922. 11 p. Diags.
D52.1 /1
Marine
D52.6/1
TS-1
D52.33/58
D52.1/l
WA
F14/9
A40.l /14
A40.l /15
D00.12/809
R. & M.
D00.12 /809
R. & M.
D00.12 /72
T. N. B.
D52.71 /48
Al0.22/28
A48.2/93
D00.12 /184
Vol. 1-No. 4
D52.1 /21
Vought
D00.12/184
Vol. 1-No. 2
D00.12 /803
R. & M .
D52.419/267
D52.16 /28
D00.12/793
R. & M.
Co-relation of model and full scale work;
bv R. M. Wood. Royal Aerona utical So_
ciety. Nov. 16, 1 £122. 5 p.
Meas uring an airplane's true speed in
flight testing; by W. G. Brown. National
Advisory Committee for Aeronautics. Tech­nical
Notes No. 135. Apr., 1923. 10 p.
Photographs, diags.
Guiding of airplanes by Loth ~ystP.m of
electric •cables ; by Capt. R. Franck and
Capt . .A. Volmerange. M. I. D. 2081 -470.
France 6983-W. Mar. 28, 1923. 13 p.
Charts. ·
Longitudinal balancing of airplanes; by
Albert Eteve. From Premier Congres In­terantional
de la Navigation Aerienne. Nov.,
1121. Vol. 4. National Advisory Committee
for Aeronautics. Feb., 1923. 6 p. Charts.
The performance of heavily loaded air­planes,
as illustrated by the T-2; by E. W.
Viehma n. Airplane Section. l'vi cCook Field,
Feb. 21 , 1923. 35 p . Photographs, chart.
Lecture on airship construction. M. I. D.
Germany . Feb. 3, 1923. 7 p.
Structural and economic limits of airships ;
by G. A. Crocco. In Italian. April 2, 1922.
4 p. Chart.
R. A. F. data regarding production of air­ship
envelopes; by 0. N. Salbert. Sept. 29,
1922. 3 p.
Practical aspect of seaplanes; by T. R.
Cabe-Browne-Cave. Royal Aeronautical So­ciety.
Feb. 15, 1923. 4 p.
Improvements in hulls for flying boats,
hig h speed launches and the like. British
patent s pecification No. 191,612. Jan. 18,
1923. 2 p. Drawings.
Influence of form of wooden beam on its
s tiffness and s trength by J. A. Newlin and
G. W. Trayer. Part I and II. Forest Pro­ducts
Laboratory. Project L-228-6. Oct. 4,
1 9 22. 68 p. Photographs , charts.
Contents:
Part 1. Deflection of beams with special
reference to shear deformations.
Part 2. Form factors of beams subjected to
trans verse loading only.
Drag of power car for fleet airship No. 1;
b y R. H. Smith and F. A. Louden. Kavy
Yard. Construction Department Report No.
215 . Feb. 13, 1923. 3 p. Photographs,
chart.
Influence of ribs on strength of spars; by
L . Ballenstedt. From Technische Berichte
Vol. 3, No. 4. National Advisory Committee
for Aeronautics . Technic~l Notes No. 139.
May, 1923. 20 p. Drawings.
Compari~on of Fokker rib with Loening
rib; Research Section. Naval Aircraft fac­tory.
Aug. 11, 1921. 4 p. Photographs.
U se of plywood in wing beams; G. E.
Hesck. Fores t Products Laboratory. Oct.
3, 1922. 23 p. Photographs, charts.
Strength properties of materials in
flanges of box wing beams manufactured by
G. Elias Brothers, Inc. McCook Field. May
11, 1923. 3 p.
TESTING.
Des cription of Issyles-Moulineaux 1000-h.
p. wind tunnel; by Lt. Col. Robert. M. I. D.
France. Mar. 28, 1923. 8 p.
Experim.ents on complete models of six
airplanes : by E. F. Rolf and E. Owen. Aero­nautical
Research Committee. Reports and
Memoranda No. 705. (Ae. 25). T. 1511.
Oct., 1920. 24 p. Drawings.
Ten years testing of model seaplanes ; by
G. S. Baker. Lecture to be given at Royal
Society of Arts on Feb. l, 1923. M. I. D.
Eng·Jand. Ja