Investigation of Junker biplane wings (Material Section report)

              Auburn University Libraries
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File D 52.1 /Junker/ 20 McCOOK FIELD REPORT SERIAL No. 1412
AIR SERVICE INFORMATION CIRCULAR
Vol. III
(AVIATION)
PUBLISHED BY THE CHIEF OF AIR SERVICE, WASHINGTON, D. C.
May 20, 1921 No. 230
INVESTIGATION OF JUNKER
BIPLANE WINGS
(MATERIAL SECTION REPORT)
Prepared by Engineering Division, Air Service
McCook Field, October 28, 1920
WASHINGTON
GOVERNMENT PRINTING OFFICE
1921
Ralph Brown Draughon
LIBRARY
MAR 28 2013
Non-Depoitory
Auburn University
/
INVESTIGATION OF JUNKER BIPLANE WIN
PURPOSE.
The purpose of this investigation was to determine:
(a) The physical properties of materials used.
(b) The chemical composition of duralumin used. ·
(c) The design and construction of the wings,
including couplings, splices, joints, welding,
riveting, etc.
(d) The method and quality of workmanship.
CONCLUSIONS.
The German Junker is the only sample of duralumin
tubular and sheet construction of German manufacture
that has been received for analysis in this country. As a
matter of record and to assist designers in preparation of
new designs of all-metal construction, a thorough study
was made of this structure, special attention being given
to the properties of the duralumin tubing, the duralumin
sheet, and to the method of making joints and couplings.
The Junker wings are good examples of practical all­metal
airplane construction. With the exception of the
strut values of the U section internal truss members, both
the design and the construction of the Junker wings are
very efficient and dependable, although it is possible that
some of the joinery could be simplified to some extent so
as to make a more practical production proposition.
The necks of some of the steel coupling parts are ma­chined
a little thin and the threads of some of the couplings
are loose.
The duralumin tubing from the Junker airplane is
smooth and even in gage and size, while much of that
from the French Breguet was rough and uneven in gage.
The ultimate tensile strength of the Junker tubing is also
greater than that from the Breguet 14-B2, as given in
Mc.Cook Field Report, Serial No. 1343, dated August 9,
1920.
It has an average ultimate tensile strength of approx­imately
50,000 pounds per square inch for the smaller
tubes and a li ttle less for the larger ones. The yield
strength in pounds per square inch could not be deter­mined
to any degree of certainty for any of the larger
tubing because of the row of rivet holes running the full
lengtli ~f one side of each, but the small tubing showed a
yield point of a little over 50 per cent of the ultimate
strength.
The low test results shown · by a few specimens were
probably due to damages received in construction or in
service. Since it was necessary to calculate corrections
for rivet holes, etc., in many cases, it is plain that some
differences in ultimate strength data must be expected.
The ductility of the tubing is erratic. The tension test
specimens necked very little and broke suddenly. The
elongation in 2 inches varied from 3 to 20 per cent and
48044---21
averaged about 6 per cent. The specimens for the crush­ing
test expanded regularly to a certain load and then
cracked suddenly.
The sheet duralumin showed a wide range in tensile
strength, probably due to the fact that some specimens had
been affected more by oxidation than others. Many
specimens showed very little ductility and in fact had a
crystallized or granular appearance in the break. The
elongation in 2 inches varied from 0.5 to 6 per cent and
averaged about 1.5 per cent.
The chemical composition of the duralumin samples
from the Junker averaged as follows: ·
Silicon ............. .... .. . ............ . ........ .
Copper . ... . ........ .. .. ... ... . ............. . . . .
Iron ...... _._. ___ .. ....... _ .... _. __ . __ _ . : .... . . .
Magnesium .... . .. .. . . . ... . ..... .... . .... ... .... .
Manganese ....... . ....... . . ......... .. ... ... ... .
Aluminum .. . . ....... ·.- ..................... ··- .. .
0.51
3.34
.81
.59
.15
94.60
which is much the same as the duralumin used. in the
Breguet airplane, excepting .that less copper and man­ganese
were used.
The wing covering had been given a coat of lacquer,
most of which had long since disappeared, leaving the
sheet duralumin exposed to the weather. Much of the
duralumin sheet was therefore seriously oxidized and
weakened, which proves that some good protective coating
must be used on exposed surfaces.
The workmanship throughout was good. Steel rivets
were used for holding members to steel fittings and parts,
but only duralumin rivets were employed for holding
duralumin to other duraluiriin.
No welds failed. Sometimes couplings, splices, and
riveted joints failed and in other instances the attached
tubing failed outside the joints, thus showing well­balanced
design.
Although the Germans depended entirely upon welding
for uniting steel parts, no welding or soldering of duralumin
was attempted in the Junker wings, which indicates that
they had no reliable process for doing this kind of work.
MATERIAL.
The following specimens were taken from the German
Junker biplane wings:
Duralumin tubing:
6 specimens-plain tension, large spars.
10 specimens-plain tension, small spars.
11 specimens-plain tension, internal truss tubes.
6 specimens-crushing or compression, large spars.
8 specimens-crushing or compression, small spars.
9 specimens-crushing or compression internal
truss tubes.
8 specimens--strut or column, large spars.
4
Duralumin tubing-Continued.
4 specimens-strut or column, small spars.
9 specimens-strut or column, internal truss tubes.
Duralumin sheet:
29 specimens- plain tension, longitudinal sheet.
25 specimens---plain tension, crosswise sheet.
54 specimens- bend test specimens.
36 specimens- Erichsen test.
Assembly test specimens:
7 specimens- wing spar couplings.
2 spetimens---splices spar tubing.
3 specimens- welded steel truss spider fittings.
16 specimens- internal truss members attachments.
4 specimens- internal truss members strut tests.
Chemical specimens of duralumin:
1 sample from No. 10.
1 sample from No. 43.
1 sample from rivets.
1 sample from corrugated sheet.
1 sample from plain sheet.
METHOD OF PROCEDURE.
Before beginning any of the tests the several Junker
wing sections or parts were thoroughly inspected and
studied, after which photographs and working drawings of
them were made for record of design and construction.
Owing to the fact that the Junker biplane w:i.s made al­m!)
st entirely of duralumin and that the general construc­tion
was radically different from the ordinary, it wae neces­sary
to test a great number of specimens in order to deter­mine
the value of both the materials and the construction.
5
The wings were covered with comigated sheet duralu­min,
which was fastened to all of the spar tubes by means
of lines of duralumin riveta spaced about 2 inches apart
along the entire length of the tubes. This made it impossi­ble
to find clear specimens of the spar tubing long enough
for the tension and strut tests. In case of the strut or
column tests this made no appreciable difference, since the
rivets were all left in the holes to give the tubes practically
normal support.
The rivets could be of no assistance, however, in the
tension specimens, although most of them were left in the
holes. All of the spar tubing was held in the testing
machine by means of the special tube chucks which were
used for pulling the tubing from the Breguet airplane.
These chucks gripped the tubes equally on all sides,
thus insuring straight pulling during the tests, which re­duced
the weakening effect of the row of holes to a mini­mum.
(See large tubing, fig. 8.)
Since there was only one hole in the circumference at
any one section, it-was necess·ary to correct for only the
one hole in the cross section of the tube when calculating
for the yield and for the ultimate -tensile strength per
square inch. This correction was made by deducting from
the original cross-section area of the tube the product of
the diameter of the rivet hole by the gage of the tube wall.
Owing to the fact that almost every type of material,
fitting, and construction to be found in any of the wing
sections was represented in the upper center wing section,
all of the test specimens, excepting the opposite coupling
parts, a few plain pieces of spar tubing, and a spar reduc­tion
splice, were cut from that wing division.
Specimens of corrugated duralumin sheet wing covering
were taken at regular intervals from one end of the wing
section to the other and marked to show locality._
Specimens gf plain duralumin sheet were taken at
regular intervals from the wing nose covering, and from the
rear internal spar web as shown on photograph.
From each piece of sheet duralum in tested several speci­mens
were cut for tension, bending, and Erichsen tests.
All specimens were numbered and their locations marked
on the photograph when taken from the wing.
In the case of the spars, several specimens were taken in
series along each tube.tested, for the purpose of getting a
check on the regularity of its material and manufacture.
(See fig. 1.)
The small truss tubes were taken from various points in
the wing.
Specimens of both sizes of end couplings were tested by
screwing them together as in service and then pulling them
by the attached tubing the same as in plain tension tests.
Truss members, both tubular and formed sheet duralu­min,
were pulled from the assembled group in their proper
working directions.
Other specimens were given plain tension, crushing, and
column tests.
RESULTS.
PHOTOGRAPHS.
Figure 1.-tlpper center section (end view).
2.-Upper center section (top view).
3.-Upper right wing. (end view).
4.-Upper right wing (tip view).
5.-Lower left wing (top view).
6.-Right-hand stabilizer (top view).
7.-Right-hand stabilizer (bottom view).
8.-Duralumin tubing, tension specimens.
9.- Wing couplings, splices, and crushing speci-mens.
10.-Cluster fittings, spars, and truss members.
DRAWINGS.
Figure 11 (M-900).- Upper wing tip.
12 (M-901).-Lower wing tip.
13 (M-902).-Upper wing center section.
~4 (M-903).-Stabilizer, left hand.
15 (M-904).-Lower wing, cent~r section.
16 (M-1251).-Spar fitting, welded sheet steel.
(From lower wing center sec­tion.)
PHYSICAL TESTS.
Table !.-Straight tension test data, duralumin tubing.
IL-Crushing or compression test data, duralumin
tubing.
III.-Strut or column test data, duraluinin tubing.
IV.-Assembly tension test data.
V.-Assembly tension test data.
VI.- Sheet duralumin tension test data.
VII.-Sheet duralumin Erichsen and bend tests.
VIII.-Duralumin chemical test data.
DISCUSSION OF RESULTS.
Figures 1 to 7, inclusive, when taken in connection with
the drawings, serve to show the general design and con­struction
of the Junker wings and stabilizers. On these
plates will also be found the locations from which all but
a few of the lesser test specimens were taken. The steel
parts all show black in the illustrations.
6
Fig. 3.
Fig. 4.
All of the parts inside of the wings were coated with a
transparent lacquer, excepting the steel fittings, which
had a coat of varnish.
The wirigs were painted green on the outside, but most
of the paint was ·gone and much of the thin duralumin
covering was badly oxidized.
Not,e the geometrical regularity of the design in figure 2
and the absence of st.eel fittings toward the wing tip in
figure 5.
All of the lower spar tubes in the cent.er section are
spliced as shown in figure 1, and all of the large upper
spar tubes in the outer sections have reduction splices
as shown in figures 3, 4, and 5. (See details of splices in
specimens Nos. 19 and 56, figure 9.) These specimens
were given t,ension and column tests, respectively, in
accordance with their functions in the wings.
The large duralumin torque tube in the center section
was not test.ed. It has an eccentric action, since it is
supported by hinge joints on the sides of the steel fittings.
Its supporting trusses at the ends are of steel tubing, torch
welded.
There appears to be no difference between the upper
and lower sides of the horizontal stabilizers, as shown in
figures 6 and 7.
Figure 8.-A few of the representative test specimens
of duralumin tubing. Not,e the squareness of the breaks
in the larger tubing and the undamaged appearance of the
ends of the tubes due to the perfect gripping by the special
holding chucks.
The smaller tubes were held by the ordinary V grips,
and their breaks were more irregular.
No. 6A shows that the coupling joint and attachment
was stronger than the tube.
The elongation in the tubing was so slight that it can
scarcely be noticed excepting in .No. 43, which shows a
little reduction.
Figure 9.- No. 19 shows, the kind of splice used in all
tube t.ension members. It consists of a scalloped sheet
steel wrapper held by four rows of st.eel rivets. This joint
is very efficient.
No. 56 shows the kind of reduction splice used in all of
the large upper spar tubes in the outer wing sections.
It is a step-down from the 1.975-inch tubing to the 1.575-
inch tubing and is subject chiefly to column loading.
The end of the large tube is squared and scalloped to four
points-two long points and two shorter ones. Four lines
of steel rivets hold the smaller inserted tubes. This speci­
·men was given the column test, which it stood to the
full, crushing strength of the smaller tube and with no
signs of joint failure.
No. GA wM tested in tension as an assembled coupling .
The tabe failed outside the coupling. The ring nut and
steel fitting part at end of No. 6A were not tested. T~ey
are included to show details of the coupling.
Coupling 2A-2B failed in tube at first line of eight rivets
in same circumference.
Coupling 5A-5B failed in tube through three rivet holes.
Coupling 4A-4B failed in neck of steel coupling part
through fi_rst line of eight rivet holes in same circumference.
Coupling 1A-1B failed by slipping coupling threads.
The tests on some of the crushing specimens were car­ried
a bit further than others, but with.no higher results.
No~. llA, 77D, 78A, and 780 show the best expansion
results.
7
Figure 10.-This plate shows the two principal speci­mens
(Nos. 7-7 and 13- 14) from whose welded steel spider
fittings the various internal tru88 members were pulled
individually after the main tubes had been given columc
tests. The minor members are also shown as examples of
failures. Note that in some of the formed sheet duralumin
members the duralumin rivets sheared, while in others the
steel ears or lugs were pulled from the fittings. The tubu­lar
truss members gave better resulte than those of formed
sheet.
Specimens Nos. 22 and 15A were tension specimens with
fittings included. No. 15:~ also had a coupling included.
fo each case the tubes failed through rivet holes within
the fittings.
Table I.-The diameters and gages of the tubing were
checked with the following results:
· Tube dimens i:ons.
Outside diameter. I . Gage.
Centi-
Inches. ~:~e~;. Inches. meters.
- - - - - - - - - ---
1.966 5.00 0. 0591 0.15
1. 575 4.00 .039-t .10
1.181 3.00 . 0394 .10
.984 2.50 . 0.194 .10
• 787 2.00 . 0315 .08
• 710 1. 80 .0315 .08
In calculating the results of the tension tests it was
necessary to make adjustments for holes in the breaking
sections. Some slight variations must therefore be
expected. The holes made it impossible to get an accu­rate
measurement of the elongation and also of the yield
points of all the larger tubing.
Table II.-It was found that duralumin tube crushing
specimens, having lengths equal to from 10 to 14 timee
their radius of gyration, · gave ultimate crushing results
approximately equal to ultimate tensile results on the
same tubing. The tubing expanded very regularly ur
to .the.point of failure and then suddenly cracked, showin2
low ductility. (See fig. 9.)
Table III.--Jn the column tests the tubes showed a bit
weaker on the side containing the rivets, which indicates
that clear tubing would have given results higher than
those obtained. All tests were made from squared or fixed
ends with ball and socket bottom plate.
The formed sheet duralumin internal wing truss rri.'em­bers
gave lower strut values than similar tubular members.
Table IV.-ln the coupling tests the resulting test data
. are report,ed only against the tube or end that failed. The
opposite end, of course, would have shown higher values.
Table V.-This table shows the t.ension results on a
varietv of internal truBS members pulled directly from the
steel fittings and in their direct worJ..-ing directions. The
relative rated or design strength of the various members
must be <let.ermined by the number of rivets by which they
were attached to the fittings. Extreme care was·exercised
in setting up these specimens for test owing to the com­plexity
of the aBSemblies.
The variety of the failures shows the design of the
various parts to be well proportioned.
Table VI.-These specimens were cut from samples
wliich were taken from various locations over the wing as
8
I
i.
9
shown in figures NOS. 1 and 2, with the exception of those
which were taken from the wing of a Junker monoplane
and reported as such.
cracks they were reported 0. K.; if some failed the sample
was reported "average," and if all failed the SlJ.mple was
reported "no good."
The several samples were marked by letter for identifi­cation
and location, and specimens cut from each were
marked by letter and number.
The tension specimens were made up in the standard
form- part of them lengthwise and part of them crosswise
of the sheet. The test results seem to indicate that the
strength and ductility of the duralumin sheet is practically
the same crosswise as lengthwise of the sheet.
From two to five specimens 3 inches square were cut from
each sample of sheet duralumin ( excepting those from
inside the wing) and given the Erichsen test for ductility,
Tab/f VIIT.-This table shows the chemical analysis oJ
samples .from representative specimens of duralumin
tubing and sheet from the Junker biplane wings.
Table VII.-Several specimeus from each sample were
given the bend test by being bent back flat upon them­selves
through 180°. If all stood the test without showing
An extract from McCook Field Report, Serial No. 134\
dated August 9, 1920, is included in this report for com­parison
between the composition of the duralumin froin
the Junker and that from the Breguet.
TABLE !.-Straight tension tests----0,uralumium tubing from Junker biplane uings.
Original Percent Corrected Per Per
Speci- Outside Gauge cross- Rivet cross- Yield Maxi- Ultimate cent cent Loca- diame- of sectional holes of cross- sectional Yield load mum strength elonga- elonga- tion of
men sectional load Remarks.
No. ter wall area in area area (pounds). (lbs./sq. load (lbs./sq. tion tion frac-
(inches). (inch). (s,iuare break. (square in.). (pounds). in.). in 2 in 4 ture.
inch). lost. inch). inches. inches.
--- - --------- --- - - ------- --- - - --- ------
8. ·-- · 1. 976 0.062 0.3728 1 2.25 Q. 3644 13,540 37,160 17, 740 48,680 ....... . ........ M.T. Broke through
rivet hole.
10 .. · - · 1.972 .061 .3662 1 2.27 .3519 9,450 26,400 17,800 49,730 · ·-·-··· ........ M. T. Do.
11. - - . - I. 974 .062 .3724 1 2.26 .3640 9,500 26,100 17,170 47,170 ·-······ -······· M. T. Do.
29 .• ·-· 1.967 .058 ·.3478 1 2. Tl . 3..199 11,000 32,360 16,980 49,960 ···-···· ····· ·-· M. T. Do.
30 .• ·-- 1.965 .058 . 3475 1 2. Tl •. 33961 9, 400 Tl, 680 11,060 32,570 -······· -------- M. T. Do.
50. -··· 1.961 .059 .3525 1 2. Tl . 3445 9,470 Tl, 490 18,800 M,570 --- ----- -------- M . T . Do.-
16 •• ·-· 1. 575 . 041 .1976 1 2.83 .1920 ----· ·- ·· · 10,360 53,960 ·------- -·-···-· M. T. Do.
17 .. ·-· 1.578 .0417 .2003 1 2.85 .1946 --· -·· ···· 10,670 54,830 ·----- -- -------· M.T. Do.
18 .. ·-· 1. 572 .041 .1!172 1 2.84 .1916 ---······· ···-···-- 10,830 56,520 --······ M. T. Do.
20 .. ·-· 1. 575 .040 .1929 1 2. 80 .1875 ----······ ·--··---- 9,260 49,390 ::::::::IM.T. Do.
21_ - ... 1.577 .0415 .2002 1 2.80 .1946 ----·-·-·· --2,;;sio- 9,160 47,070 ·------- M.T. Do.
23_ ···- 1. 574 .041 .1975 1 2.84 .1919 5,280 10,720 ~t~ - - -- ·-·- M. T. Do. -
24. - ·-· 1.572 .041 .1972 1 2.84 .1916 5,000 26,100 7,340 · - · -- ·-- M.T. Do.
25_. ·-· 1.575 .041 .1976 1 2.83 .1920 5,700 29,690 7,360 38,330 -··---·· M.T. Do.
26 .. -·· 1.580 .042 .2030 1 2.81 .1973 -- ·-·---·- -------- - 7,280 36,900 ---···-- M.T. Do.
55 .. -·. 1.567 .040 .1919 1 2. 81 .1865 -·----- · -· ·-···---· 10,400 55,760 -----·-· [ M. T. Do.
43. ·- · - 1.182 .042 .1504 0 ·-------- --------- 4,370 29,060 8,230 54,720 20.00 17. 75 M. T. Square break.
44_ - ••. 1.178 .038 .1361 0 --·····- · -----···· 2,780 20,430 7,390 54,300 6.50 5.25 M. T. Do.
40_. --· .982 .039 .1155 0 --------- ------·-· 2,620 22,680 6,780 58,700 6.50 6.00 0.S.T. Do.
41.. - . - .982 .039 ,1155 0 --·-· ··-· --------· 4,800 41,560 5,650 48,920 3.50 2. 75 M. T . Do.
42_. ·-· .985 .041 .1216 0 --- ---- -- ·-------· 3,900 32,070 6,670 54,850 12.00 11. 75 O.S.T. Do.
34 . . . .. . 786 .032 .0758 0 ----- ---- · ··-·· ·-- 1,980 26,120 4,320 m,ooo 7. 50 6.00 O.S.T. Do.
35 ..... . 793 .032 .0785 0 -·- ·· · ·-- -·-···-·· 2,620 34,250 2,980 38,950 3.00 2.50 O.S.T. Do.
36 .• ... . 788 .032 .0760 0 ----·-··- ---······ 2,000 26,320 3,760 49,470 13.00 12. 75 0.S.T. Do.
33_. ·-· . 711 . 031 .0662 0 ---- ·---- ----·---- 2,340 35,350 3,450 52,110 3.50 3.25 M. T. Do.
37_ .... . 711 .031 .0662 0 --- ----- - --------- 1,500 22,660 3,430 57,810 7.50 6.50 M.T. Do.
39. _ ··- . 714 .032 .0695 0 ----·---- ········· 2,020 29,060 3,600 51,800 13. 00 11.50 M.T. Do.
A line of rivets spaced about 2 inches apart to hold corrugated duralumium wing covering made it impossible to get the elongation in the
larger or spar tubing above.
Specimen No.
TABLE II.-Duralumin tubing-crushing tests.
Length Outside
(inches). diameter
(inches).
Gage of
wall
(inch).
Cross­section
area
(square
inch).
Yield Maxi-
Yield load mum
load (pounds/ load
(pounds). .square (pounds)
mches). ·
Ultimate
load/
area/
square
inches).
1/r. •
- - ----------------1--- - ----- --- ----------------------- -
lOA •. ·· · · · · · · · · · -· · -·· - ··· -· -·-- -- - · ·· · ··· ··-······
llA ... ··············-·················-····-·-·-···
29A·-··········-·······--·····-················-'··
30A--··········--·····-······· - ··· -- · - ··· - ·-·- ·····
51A--·· --··· ··--·····-- ---· · ·-·-··· · -- ·- -· ·· - ·-····
51B·-·- -··-·· ·· -- ·-·· · · · -·-·-··--·······-···· ····· ·
17A ..... ·--···-·-··· · ·-···· · ················ ··· -···
18A ..... ...... . ........... .......... ·-··- ··-· -·····
19A·-··· - · · ······ · · -···-············ · -·- ·· ·· · · ···· -
::t:::::::::::::::::::::::::::::::::::::::::::::::
24A ••.......... ·-··· ·· -·-·····-·-· ·· ····-··-·· - · · ··
25A·---·-·····-·············· - · · ·····- - - · -···-·· · ··
49A-···· · - ·--· ··--- -- · - ----- - - --- - ·- · ·-- · - ··· · ·····
77A_····· · ··· · · · -- -· - · ---· - · - · ---- - -· · ·-·-·········
77B. ······-·········· - · - · - ·-· ' · - ··· · ········· ··-··· nc .. . ·-·····- ·-:··· ·- -·· ···- ---·· ··· -···· ··--·· ··-
77D ... . ...... -·- · · - -··· ··· ·· ··-···-·--··· · -·-·· · ···
77E .. ·-··-· ··-· - · -·- ·-· -·-· · ·-·-·· ··- ·- ·····-·-· · ··
77F ·····-··-·-·· -· ···· - -·-·-·-· - ····-·····-·- -- ·-··
78A ... ·-·---····· · ··-····· ··· ·-·······-·· ·- - · ---···
78B·-·--- ' ··· · -·-·-· - ·-·-·-· -· ··-···--··--··· · ·····
78C ••••••• . ·-··· - ····- - ··· · ·-···-· · ·-·-···· · ·· - ····
• 1-length; r-radius of gyration.
1. 970
1. 980
1.970
1.960
1.980
1. 980
1.600
1.610
1.580
1.580
1. 620
1.600
1.590
1.590
. 786
.813
.821
1.114
1.110
1.107
1.135
1.132
1.133
1.974
1. 972
1.965
1. 962
1.972
1.972
1.575
1.575
1.575
1.576
1. 578
1. 576
1. 575
· 1.ii74
. 787
. 787
. 786
. 786
. 787
. 786
• 788
• 784
. 789
0.062
.061
.058
.058
.060
.060
.042
. 041
.041
. 041
.041
.041
.042
.040
.033
. 033
.033
.033
.033
.033
.031
.030
.031
0.3724 13,000
.3662 12,250
.3475 14,000
.3469 13,250
.3604 13,000
.3604 13,000
.2023 7,200
.1976 7,500
.1976 7,000
.1978 7,250
.1980 8,600
.1978 5,400
.2023 3,750
.1928 · 6,250
.0782 3,200
. 0782 3,100
. 0781 2,500
.0781 2,900
.0782 3,000
.0781 2,875
.0737 2,400
.0711 2,100
.0738 2,100
34,910 17,850 47,920 11.44
33,450 17,500 47,790 11.60
40,290 17,500 50,360 11.85
38,200 17,500 50,450 11.80
36,070 19,400 53,830 11. 692
36,070 19,300 53,550 11. 692
35,590 10,300 50,910 12.62
37,960 10,200 51,620 12. 84
35,430 9,500 48,080 12. 60
36,650 9,300 47,020 12. 60
43,430 10,750 54,290 12. 907
27,300 7,500 37,910 12. 756
18,530 6,000 29,660 12. 533
32,420 8,500 44,090 12. 838
40,9'.!0 4,200 53,700 9.96
39,640 4,100 52,430 10.30
32,010 4,000 51,220 10.42
37,130 4,150 53, 140 14.14
38,360 4,100 52,430 14.07
36,810 4,150 53,140 14.05
32,560 3,200 43, 420 14.82
29,540 3,200 45,010 15.05
28,460 3,320 44,990 14. 78
10
Fig. 7.
'
1
Ouralumin Tubtn9 Tension Specimens~ Junker Wl@S.
1
Fig. s . :
11
TABLE III.-Duralumin tubing-column test.
Le~th d~!!i:r G!~bof
Cross- I Maxi- Ultimate
section mum load/area/ Specimen No. J/r.
(inches). (inches). (inch). area load square <~ih).~ (pounds). inches.
- ----- - --- ---------- ----- ---1---- -------- -------- - --- ----
9 .••..•••.••••••••••••• •• •••• • •• . • ••• •••••••. .• •••• ••••...•.••.•••.• •• • . •
12 . ..... . ... .... ... .......... .. . ·-- . .. ..•. ... ...•.. .. .. ·-· . . . . - - - . - . . ... -
27 .. .... . ....................... . ............ . ············· · · · -- · -···· .. .
28 ...................... . ......... . ....... . . .... ............. ... ........ .
31. ... . - ·--- . . - . -· ..... ··- . - .. . ·--·- ... ·-- ...... - .................... - -..
32 .... ······-······· ········ · ··· ·- - · · ·· ··········· · · ·····- ........ . : . . .. .
46 .................... . .................. . . ..•. . .. . ..... .... . . . . .. .. .. . ..
49 ............................ ····· ......... . ... . ........ . ···-· · · ··-···· ·
53 ........ . ... . . .......... .............. .. . ............................. .
54 .•......•.•••••••••.. • ••• • •• • • •••.• • • ••• .. • . • . ••. • .• ••• . • , ...••••.••.••
13- 14 .................................... . ......... . .. . .•. . . . ..•. .. . .....
7-7B ................. . .......................... . ...................... .
56A ...... . . . . •..............•..........•....•.•....•......•........•....
56B ....... . .•. .. ...• • . .•...• . • . .... . .....•....•........•....•......••...
79 ......... . ........... .. .. . ·· · · · ·· ····· -· · · . .. .•. ... ..• .... .... . .... . .. .
80 .......................... . .. ........................ . ........ . . ...... .
81. .... . - ... .... ... .. .. ... ......... .... . - ....... .......... .......... . ... .
82 .... . . . .•...... .•. . . . . .. ..... ..... ..... ...... . ... . .. ... ...... ... .......
83 .•..•.•.••...•.•..• . • .. .•.••.• • •.••• ••• •• ••.•••• • ••.•••• . ••••• ... • .••••
84 ... .. ................ .. ....................... · . ... : ...... ... ........... .
85 . ......•...... ....... . ................... · . ... ..... . ..... ........... ... .
86 ..... • . •. .. . ..•. ... . • . .... . . ........... .... . ....... . .......... .. ..... . .
87 ..... . . . ...•...•... . •.... . .. •. ...•.• ••••• .• •••.• ..• • . • . • .••• • . • . ·•·•· · ·
21.35
23.10
21.36
21.80
2211.. 3804 1
23.38
20. 50
22.66
22.65
41.00
34.00
(')
• 17. 35
23. 7&
10.62
11. 40
11. 40
11. 56
11. 56
14.50
13. 20
14. 52
1. 975
1.972
1.966
1. 967
1. 965
1. 963
1. 572
1. 572
1. 573
1. 576
1.972
1. 971
1. 567
1. 970
1.182
.985
.990
. 987
. 791
. 790
. 794
. 782
• 775
U-SECTION DURALU:MIN MEMBERS.
88 .. . .... .. ..... . ............................. . .... .... . ... .. ......•.... .
89 ....... . . . . ... . ... .. . . ...• : ........................... ...... .... . .... ..•
90 .. ..............•.. . . . ..• . . . . . .. ... . .... .. . . . .• ..... .. ..... . .. . .. . . . ...
91. ..... .. .. . ...... . ....... . ............................................ .
14. 32
14. 34
16. 'J:7
16. 27
•3. 68 1 • 3. 65
• 3.26
• 3. 26
I
0.061
. 061
.058
058i'
.058
.059
.041
.040
.040
.040
. 061
.061
.040
.060
.042
. 040
.043
.043
.031
.031
.034
.028
.029
.030
.031
. 031
. 030
0.3668
.3662
. 3477
.3478
. 3475
.3529
.1972
.1926
.1926
.1931
.3662
.3660
. 1919
.3600.
.1504
.1188
. 1279
.1275
. 0740
. 0739
. 0812
.0663
.0680
.1104
.1132
.1012
.0978
15,910
15,400
15,690
15,640
15,860
15,810
8,070
7,970
8,030
7,690
11,690
15,200
10,460
10,460
5,890
5,630
3,840
5,700
3,790
3,440
3,030
2,720
2,850
2,090
1,870
1,840
1,340
43,380
42,050
45,130
44,970
45,640
44,800
40,920
41,380
41,690
39,820
131,920
'41,530
54,510
54,510
39,160
47,390
30,020
44,710
51,220
46,550
37,320
41,030
41,910
124. 96
135. 32
128. 42
130. 84
128. 33
130. 16
186. 64
165. 63
183. 02
182. 76
240.17
199. 22
• 12.14
• 53. 17
125. 69
109. 47
112. 98
113. 21
i50. 12
150. 72
180.:i5
182. 32
197. 55
'18,930 I··-······ • 16,520 ··- · - ·····
818,180 1··· · ··· ·· ·
813,700 ······ ··· -
1 Strut tube members through steel spider fitting located two-fifths from end. Upper spar tube.
• Strut tubes through joints. These were upper spus, hence compression members in flight. Joint fitting one-third distance from end.
, 1.50 inches - free end of spliced specimen. .
• Calculated on estimated length of each tube in the splice.
, Total length of spliced specimen.
• Developed width of sheet.
1 Open side collapsed .
• Bent edgewise.
TABLE IV.-Wing spar coupling-assembly tension---4uralumin tubing and steel couplings.
Out- Original Corrected Per Yield Ultimate
side Gage of croasrse as,e c- craosrse as,e c- bNeurmof- ceanret ao f Yield load Mmauxmi- strength Specimen No. diam- wall tion tion rivet lost load (pounds/ load (pounds/ Remarks.
eter (inch). (square (square holes . by {pounds). square (pounds). square
(inches). inch). inch). holes. inch). inch).
- ----- ------- - --.--- --------
lA .....•........... 1. 973 0. 061 0. 3664 0. 3176 5 13. 32 8,760 23,910 12,300 38,730 No tube failure.
lB ................. 1. 973 . 061 . 3664 5 8,760 . 23,910 12, 300 38,730 Do.
3A . . ......... ...... 1. 970 .062 . 37164 .3032 8 18.42 6,870 18,490 14,'J:70 47,060 Cou£i~g threads slipped.
3B . . ... .•... . . ..... 1.975 .061 .3668 . 31433 5 24.30 6,870 18,490 14,270 45,400
4A ..... . ........... 1. 961 . 059 .3525 ... . ...... -····· ········ --- ------· ·· · -······ ········ ·· -······· · - No failure.
4B ............. .. .. 1. 975 .061 .3668 . 2984 8 18.65 7,300 19,900 11,020 36,930 Steel coupling neck broke .
2A .. .... ....... ... . 1. 573 .041 . 1973 . 1504 8 23. 77 ------ --- - ··----···· .......... 63,300 No failure .
2B . . ....... .... . ... 1. 575 .041 . 1976 . 1522 8 22.93 ..... . . ... ··· ·· ·--·· 9,520 62,590 Tube failed .
5A . . ..... . ........ . 1. 576 .043 . 2071 .1890 3 8. 74 ··- ·· · -··· ·· ······ ·· 6,730 35,610 Broke through rivet holes .
5B ................. 1. 579 .041 .1981 . 1512 8 23.67 -···· ····· ····---·· · -·-······· 44,510 No failure .
6A .... . ............ 1.576 .043 . 2071 .2013 l 2.80 --········ --····-··· 9,230 45,850 Broke in tube away from
joint.
6B ............. •. . . 1. 575 .041 . \976 .1921 2. 78 ---· ··-··· .......... .......... 48,050 No failure.
15A ... . . . . . .••.. . . . 1. 576 .042 .2025 .1716 5 15. 26 --· · ·· --· · ··· ···· ·· - 9, 960 58,040 Broke in edge of fitting.
15B . . ..... . ........ 1. 579 . 041 .1981 . 1528 8 22.87 ······-··· ····· · -·· · .......... 65,180 No failure .
22 .................. 1. 575 . 042 .2023 .1712 5 15. 37 ······-·-· --·-··-··· 8, 700 50,820 Pulled through spider fit-ting.
19 .... . .. ........ . . . . 1. 576 .041 .1978 . 1752 5 11. 43 .......... ···-······ 8,960 51,140 Tube failed outside, splice .
NOTE.-All test data are based on dura!Ulllin tubing and not on steel parts.
12
Fig. 9.
TABLE V.-Assembly tension tests-duralumin tubular and sheet U section internal wing truss members.
Speci-
Speci-men
men cross-
No. section
form.
------
62 Tube.
64 Tube.
63 Tube.
60 Tube.
61 Tube.
65 u
66 u
67 u
73 1 Tube. I 74 Tube.
76 Tube.
68 Tube.
69 U
70 U
71 U
72 U
Outside Devel- diameter oped
(inches). width
(inches).
------
1.15 -········
1.183 ···-····· .987 .........
. 790 ·· ··· ··· ·
. 792 ········· 3.20
... ...... 3.20
·-· ------ 3.20
o.. 778869 1.··.·.·.·.·.·.··.1.
.788 , ..... .. ..
0.788
3.62
3.60
3.20
3.20
SPECIMEN PULLED FROM TUBE NO. 7-7B.
nross- Corrected Steel Ultimate I Gage of section cross- Rivet Maxi- section rivets holes mum strength
wall area holding (pounds/ Remarks.
(inch}. (square (saqrueaar e mem- briena k. (polouandd s}. square inch). inches). ber. inches).
-------------- -------
0.041 0.1429 0.1294 4 4 3,590 27,740 Tube failed in flat.
.042 .1505 .1297 5 6 4,600 35,470 Do.
.042 . 1247 . ll08 4 2 3,960 3-5, 740 Do.
.029 .06933 . 06933 3 ... . .... 2,000 28,850 Tube failed 2 inches from end.
. 029 . 0579 .0388 3 4 2,200 56,700 Tube failed in flat.
. 030 . 0960 Spliced. 3 12 1,780 18,540 6 duralumin rivets sheared.
.030 .0960 Spliced. 3 4 2,180 22,710 Steel fitting lug failed.
. 031 .0992 Spliced. 3 4 2,250 22,680 Do.
SPECIMENS PULLED FROM COUPLING FITTING NO. 15-A.
o. 031 I o. 07382 I 0. 0431
I ~ 1
. 040 . 09375 . 0674
.030 .07145 .0517
SPECIMENS PULLED FROM
o. 030
.030
.030
.030
.030
0.07145
. 1086
.1080
. 0960
.0960
0.0.517 3
4
4
3
3
:I 1,740 I 1,520
1, 890
22,550 Steel fitting lug falled.
40,370 I Tube and steel lug failed .
36,560 Do.
TUBE NO. 13-14.
4 1,770 34,240 Tube failed in flat.
8 2,200 20,260 4 duralumin rivets sheared and 2 tore out.
8 2,100 19,440 Do.
4 1,990 20,730 Steel fitting lug failed.
4 1,910 19,900 Do.
NoTE.-AII tubes are stamped flat at ends and held to steel fittings by steel rivets. Thus each rivet makes two holes. All U-section sheet
members have channel fishplates held in ends by 6 duralumin rivets. These plates are held to fittings by steel rivets the same as the tubes.
All test data based on cross section of duralumin member.
.I
I
I
13
Fig. 10.
TABLE VI.-Duralumin sheet-tension tests.
STANDARD FLAT SPECIMENS LENGTHWISE OF CORRUGATED SHEET.
Yield Ultimate Elonga- Elonga-
Thick- Area (pounds Maxi- strength tion tion Location
Specimen No. Width
(s~are
Yield mum (pounds in in of Character
(inches). ness (pounds). per (inches). inc es). square load per 2inches 4 inches of fracture. (pounds). square (per (per fracture.
inch). inch). cent). cent).
- - ----------------------- - - - ---------____ , ____ A-1. .... . .............. . . . . .
A-2 .. . .......... . • .. . .. .••. .
B-1 . .... ... .. .. . ....... . ... .
B-2 . .• . .... . ..... ..... .•....
C-1.. ······ ···· ······· · ·····
CD--21 ·.·. ·.·.·.·.·.·.·..·.· .•·.·.·.·.·.·.·.·.•..·.·.· ·.
D-2 ...... . . ......... . ...... .
E-1 ..... . ......... . .. . . ... . .
E-2 .. . . . . . . ... . ... .. .• ... . . .
F-1 • .. ... . ........... ..... ..
F-2 ....... ..... . .... .. .... . .
G-:1 .... .. ... ........... .... .
G-2 . ....... .. •.... .. • . . . .. . .
H-1 . ...... .. ..• . ............
H-2 ........................ .
AC-1. ... . . .• ....... ... . .... .
BC-1. . . . . . ....... . ...... ....
BC-2 ....... ... .......... . .. .
CC-1 .................... ... .
CC-2 . . . .. . . .... . ...... . ..• ..
DC-1. ............ . . ...... . ..
DC-2 •••............ . • .......
EC-1. .. ...... .. . .. ... .. .... .
EC-2 ..... .... .. ... .. . . .... . .
FC-1. . ... . . .. .. . ..... ... ....
FC-2 ............ . .. . . .. . . ...
GC-1. ......... ... .. .. . ..... .
GC-2 .•. ... .. ... . .......... . .
HC-1 ...... . .............. . .
HC-2 . . • .... ... .... . ........
HC-3 . ..• ... •. . . ... .........
0. 680
. 756
. 750
. 750
. 750
. 746
. 749
. 754
. 754
. 747
. 741
. 749
• 751
. 750
. 752
. 742
0.013
.013
.012
.011
.013
.013
. 012
.012
. 012
.013
.013
.013
.014
. 012
.013
.013
0.00884
.00983
. 00900
.00828
. 00975
. 00968
.008\J9
.00904
. 00905
. 00971
.00963
. 00974
.01051
.00900
. 00978
.00965
250
205
225
180
235
250
260
28,280
20,850
23,080
18,560
26, 140
'J:1,650
28, 730
305 34,500 ....... .. ... ..... . . .
305 31,030 0. 50 0. 50
2'>0 'J:I, 780 1.00 . 75
140 16,910 .. .............. ... .
310 31,790 1. 00 . 75
195 20,110 ... ..... . . .. ....... .
325 36, 150 2. 00 1. 25
300 33,190 1. 50 1. 00
370 40,880 .... ... ....... ..... .
340 35, 020 . .. . ....... ...... . . .
240 24,920 340 35,310 ................... .
'1:10 27, 720 350 35, 930 1. 00 . 75
275 26, 170 3&5 36,630 2.50 2.00
190 21,110 320 35,560 1.50 1.00
.... ....... .. ....... ···· · ····· . . ........ 1.50 1.00
200 20, 730 330 34, 200 . . ....... . . . .. .. ... .
STANDARD FLAT SPECIMENS CROSSWISE OF CORRUGATED SHEET.
0. 750 0.013 0.00975 160 lG,410 240 24,620 0.50 0.50
. 749 .012 .00899 150 16,690 180 20,020 ···-·· · ·· · . 25
. 750 .012 . 00900 130 14,440 145 16,110 ... ... .... ··· ·-·-·--
. 750 .013 . 00975 240 24,620 310 31,800 1. 50 1. 00
. 751 . 013 .00976 230 23,570 310 31,760 2.00 1.00
. 749 .012 . 00899 150 16, 690 280 31 , 150 I. 00 .50
. 750 .012 .00900 200 22,220 290 32, 220 . 50 .50
. 748 . 012 .00898 160 17,920 220 24,500 .50 .50
. 748 .012 .00898 ·········· -·- ···· ··· 190 21,160 1. 00 . 75
. 749 .012 .00974 256 26,280 290 29,770 1.00 . 75
. 749 .012 .00974 240 24,640 260 26,690 1.00 .75
. 749 .012 .00899 244 'J:I, 140 280 31,150 1.00 .75
. 746 .012 . 00895 280 31,280 426 47,600 6.00 4.25
. 748 . 013 .00972 .... . .... . ·· · · ··-··· '1:15 28,290 .50 .50
. 748 . 013 . 00972 250 25,720 318 32,720 ····· ··--· ·· -······· . 750 .012 . 00975 200 20,510 340 34,870 . 50 .50
0. S. T .. Ragged.
~: :i;: : : : SCJ8~re.
0. fl. T ... Ragged. 8J L SCJ8~~e.
0. S. T .. Ragged.
M.T .... Do.
O.S.G.. Do.
0 . S. G .• Square.
O.S.G. . Do.
JILT... . Do.
M.T .... Do.
JILT. . .. Do.
M. T .... ·Ragged .
O.S.G.. Do.
M.T .... Ragged.
O.S.T . . Granular.
O. S.G .. Do.
O.S.T .. R agged.
M.T .... Do.
M.T .... Do.
0.S.G .. Do.
LG .... . Granular.
0.S.T .. Do.
0 .S. T .. Ragged.
0.S.T .. Granular.
O.S.T . . Do.
O.S.T .. Ragged.
O.S. T .. Do.
0.S.G .. Square.
M.T .... Ragged .
14
TABLE VI.-Duralumin sheet-tension tests-Continued.
STANDARD FLAT SPECIMENS LENGTHWISE OF PLAIN SHEET.
Specimen No.
Yield Ultimate Elonga-1 El6nga-
Thich- Area (pounds Maxi- strength tion tion Width Yield mum (pounds in in Location Character
(inches). (inncehsess ). i(nscqhueasr)e. (pounds) . sqpuearr e load per 2 incnes 4 inches fracotfu re. of fracture.
inch). (pounds). square (per per
inch). cent) . cent).
---------------------- -----
I - X ... .•.. . • .. . • . • . ... . . : .•• 0. 744 0.017 0.01265 230 18, 180 465 36,760 1. 50 1. 25 M.T • . •. S'J8~~e. J-1. • . . ..•..•. . • •.•.•. ... . .•• • 750 . 016 300 35,000 500 41,670 3.00 2.00 M.T ....
K- 1. .....•.•... . .. . .... .... • • 747 .016 . 01195 310 25,940 500 41,840 2. 50 1. 75 M.T . . .. Ragged.
K- 2 ..•............ . ..•... . .. • 748 . 016 . 01197 ··· ··· ·· ·· .... .... .. 355 29,660 ····· ·---- ---------- 0.8.G .. Do .
K-3 •.....• . .... . .. .... . . .... . 746 .016 . 01194 310 25,960 460 38,530 1. 50 1.25 0 . S .T . . Square
L-1. .... • .. ... .. •. . ... .. ...• • 744 .016 .01190 330 27, 730 470 39, 500 1. 50 1. 00 M.T . ... Ragged .
N-1. . . ....•..... ....... ..... . 748 . 015 .01122 220 19,610 375 33,420 5.50 3. 75 O.S.T .. Square.
N- 2 •.....•.....•. .. .... .. ... . 751 .016 . 01202 210 17,470 360 29,950 4.00 3.50 O.S.T .. Do •
0 - 1. ••. . . . ...•. . ...•.... . ... . 750 . 016 . 01200 310 25,830 520 43,330 3.50 3.25 I. G . . . .. Do.
0 -2 . ... .. ..•...... . .. ... . . . . . 742 .016 . 01187 280 23,590 540 45,490 4. 00
3. 75 1
M.T . ... Do.
P-1. ... •. .•.. ... .. .. .. . .. .. . . 740 .017 .01258 320 25,440 470 37,360 1. 50 1. 00 O.S.T . . Ragged .
P-2 . ... . .. . ... . ...... .• . . . . . • 754 .017 . 01282 325 25,350 565 44,070 1. 50 O.S.G . . Do .
STANDARD FLAT SPECIMENS CROSSWISE OF PLAIN SHEETS.
KC-1. . . . . .. ......... . .. ." ....
I o. 749 0.016 o. 01198 280 23,370 380 31, 720 0. 50 0.50 O. S. T . . Ragged.
KC-2 ........................ . 749 . 016 . 01198 ·····- -- -- -- -- ------ 220 18,360 1.00 .50 M.T ... . Graunlar .
MC-1. .... . . • . ..... . .•.. . .•.. . 749 .017 • 01273 250 19,640 310 24,350 1. 00 . 75 0.S.T .. Do.
NC-1. ..•....•... . ........ . .. . 745 .016 . 01192 300 25,170 484 40,600 1. 50 1. 00 0 . S.T . . Square .
NC-2 . .....•.... . ....... .. .. . . 747 .017 .01270 225 17,720 494 38,890 1.00 1. 00 M.T .. . . Ragged.
OC-1. ... .. . • .. ... •.• .. . . . .. . • 745 . 017 . 01267 320 25,260 495 39,070 5.00 3. 75 M.T . ... Do .
PC-1 . . ..•............... . . . . . 748 . 017 . 01272 340 26,730 504 39,620 2.00 1. 50 O.S.T .. S'J8~:•· PC-2 . . ............ . ... . ..... . 752 .017 . 01278 ...... i~ { J g~g" 284 22,220 1. 50 • 75 M. T ....
RC-1. .. .. ..... . .... ... ..... . • 748 .016 . 01197 140 I 11,700 . 50 . 50 M.T . . .. Ragged.
XC-1. ... . .•..........•.... • . . 751 . 016 ,01202 380 I 31,610 1.00 . 75 M.T . .•• Do.
SPECIMENS FROM JUNKER LARSON MONOPLANE WING. • STANDARD FLAT SPECIMENS LENGTHWJSE OF PLAIN SHEET.
LA- 1. ..• . ... .•. .. ....•...... 1 o. 749 1 0.0181 o. 013481
4251 31, 530 I 670 I 49,700 I 5.00 I 4. 50 1 1. G .. . . · \ S'J8are.
LA- 2 ... ... . . .•. ..•. ..•. . ••.. • 746 .018 • 01343 300 22,340 690 51,380 9. 00 7.50 M.T. . .. o .
LA-3 ...•..... ... • . ... •... . .. . 745 . 018 . 01341 380 28,340 630 46,980 5.50 3. 75 M. T.... Do .
STANDARD FLAT SPECIMENS CROSSWISE OJI PLAIN SHEET •
.:.u.. .......... I 0. 7481 0.0181 0.013461 gl 29,720 I 6651 49,410 I 6.00 I 5. 251 M. T . .. · 1 S'J8a re.
LAC-2 . . .. . . .• .• • ... ... .. . .. . 747 . 018 . 01345 23,700 690 51,300 7.00 5.00 M.T.. . . o.
LAC-3 .... ... . .............. . 749 .018 .01348 380 28, 190 690 51,190 7.50 5. 00 I. G..... Do.
STANDARD FLAT SPECIMENS LENGTHWJSE OF CORRUGATED SHEET.
LAP-1. ....... . . ... . ..... . .. 1 o. 745 1 . 0.0181 o. 01341 I 450 I 33,560 I I 38,030~ 1.251 M. T .... , Ragged.
LAP-2 ..... . .. ..•. ...• ... . .. . 745 • 018 .01341 395 29,460 510 38,030 2. 00 1. 25 0. S. T .. Square .
LAP-3 .............•..•.. . .• . 748 . 018 . 01346 400 29,720 540 40, 120 1. 00 . 50 M. T . . ..
1
Do.
TABLE VII.-Erichsen and bend tests-Duralumin sheet from Junker biplane wings and Junker-Larsen monoplane wings.
SPECIMENS FROM CORRUGATED SHEET-JUNKER BIPLANE.
Specimen No. I
Erichsen tests, _ ________ , ____ B_e_n_d_t es_ts. ___ _
First Second Third Fourth Fifth A a e Specimen SpecimenJ Results.
specimen. specimen. specimen. specimen. specimen. ver g · O. K. failed.
------------- -----1---- - ------ ----- ----------1--- - -
A . . ........ . .. ... . ..... . . .. .... . ... . .. . . . . ...... .
B ....... .... ....... .. . . ..... .. .... .. ..... . ...... .
C . . . .. . . ... .... . ....•. •.• ... •..•.•.....•. . •. ... ...
D . .... . .... . ... ... . ....... . . .... . . ........ . ..... .
E .......... . . .... . . . . . ... . .......•.. .. .•.. . .... ..
F .............. . . . . ....... .. . . . . ... ......... . ... .
0 ......... . .... .• . ... ... . ........ . ...............
H ..........•... . . . ... . . .. .. • . . . . .. .... . ..........
2. 56
2.59
2. 76
2. 90
4. 74
3.54
3.56
2. 62
1. 90
2. 31
2.42
2.55
2.60
5. 70
2.94
3. 10
2.69 2.69 · ···.•· · ·· · ·
Sl;'ECIMENS FROM PLAIN SHEET-JUNKER BIPLANE.
2.46
2. 45
2.59
2. 72
3.67
4.62
3.25
2.86
3 5 Average.
0 7 N .G.
4 3 Average.
5 1 O.K.
3 2 Average.
1 0 O.K.
4 0 O.K.·
0 2 N.G.
§::::::::::::::::::::::::::::::::::::::::::::::::: u~ Ull t~ ·-- ··2:2r :::::::::: U1 g I l ~: 8:
K............... . . . .. . .. ... . . ... ... . ....... . . . . . .. 2. 76 2. 05 .. . .. . .... .... . . . ... . ...... .. . 2.40 O 5 N. G ..
L.................... . ... . .. .. .. .. . ... . .. ........ 2.84 2.63 3.05 2.50 .......... 2.75 0 3 N.G.
N . . ........ . ...•... . .... • . ... .. . ........ . . . •... .. ••·· •·•· · · · ·• · • ·• ·• · ..•••.. . ••••..•••.• . ··•·••••·•··•·····•· • •··•· ···· ···· · · · ·•·
0 ..... ... ............... . . ...... .. ...... . .. .. . . .. ····· · ···· .... . .. .. . · · ···· · · · · · ·· · ······ .... . . .. .. ··· · ······ .......... · ·· · · · ··· ·
P. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . 2. 62 2. 33 2. 98 2. 43 2. 71 2. 61 2 0 0. K.
R.. .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3. 02 1. 97 ' 2. 66 1. 81 2. 37 2. 37 ... . . .. . . . .. . . ..• . •.
i
SPECIMENS FROM CORRUGATED SHEET-JUNKER-LARSEN MON:OPLANE .
LAP .... . . .. ..... .. ...... . .................... . .. , 4.60 I
5.11 !·········!········· ·I 4. 721 31 N.G.
NOTE .-Specimens are from same sheet samples as t ension specimens of same letters.
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ENGINffRING 01 \( lOW~R c~11re.11 sei:Tt OI'/ · 11-904
FIG. 15.-M-904--Lower wing, center section .
<;.------.
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FIG . 16.- M- 1251-Spar fitting, welded sheet steel (from lower wing center section).
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15
TABLE VIII.-Duralumin chemic.al analysis.
CHEMICAL COMPOSITION OF DURALUMIN SAMPLES FROM JUNKER BIPLANE WINGS.
Sample from specimen. Si. Cu. Fe. Mg. Mn. Al.
------------ --- -------------------------- ------------
Tube No.10 ................... .. .............. ... ... ........ ............ ..... ... . .
Tube No. 43 ..................................... . ...... ... ... . ......... . ...... . .. .
Spar rivets .......... ....•. .. . . .• .. .. .. .•..... .• .•... : . .. •.......• .... ...• . . .. .....
Corrugated sheet .•... .. .. .. .... ...... ... .. .................. . . .. .. . . .... . ..... .••. .
Plain sheet ....... . ............................................... · . · . . . ..... · · · · · ·
Average .............. .. • .. .. .. .. • .. . .................... .. . ········· ···· ····
0.51
• 4()
.53
. 71
. 41
.51
3. 31
2. 77
2.66
3.86
4.10
3.34
0.61
. 41
. 87
. 66
1. 48
. 81
o. 62
.60
.60
. 55
.58
.59
CHEMICAL COMPOSITION OF DURALUMIN SAMPLES FROM BREGUET FUSELAGE.
(Copied from McCook Field Report No. 1343, for comparison.)
Tube No.4 ............................... . .......... : ..... ... .......... . . . ... .... . 0.50 3. 30 o. 34 o. 33
Tube No. 5 ...... ..........• .. ...... ... . . . .... •••••.••.. . •..• . • . . ....•.......... . .. .38 3.45 . 39 . 28
Tube No.16 .. . .................... .. . . ................. ... . .. .... . . .. . .... . ...... . .43 4. 51 .38 . 31
Tube No.20 ......... . ........ . . ... . . .•. .. . . . .•... .... •.... . ..... . . ...• . .. . . .. ..... .53 3.61 . 40 . 25
0.12
.20
.17
. 11
.15
. 15
0.88
. 89
I. 28
.95
- - ------ - - - - - ---
Aver~ge ........... ........... .. .... ...... ·· · · ··· · ··· · ··· ··· ······· ··· ·· ·· · · · .46 3. 72 . 38 . 29 I. 00
0
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Diff.
94.60
Diff.
Diff .
Diff.
Diff .
---
94.15