CASE FILE Co

CASE FILE co

TECHIICAL LIEMORANUI.:S

1TATIONAL ADVISORY FOR AERONAUTICS

No. 608

THE USE OF ELEKTRON MTAL liT AIRPLANE CONSTRUCTION By E. I. de Ridder

Jahrbuoh 1929 der Wsenschaft1iohen Oesellschaft fi.r Lu±tfahrt

This nmuua ON W* F** Nt R

NATIONAL MWOlY COMM4!TI K* AEONAIrnr L&JIG1Y PVVOKIAL *€O$*tlT%C*t. LAaOPA7OPY LANG&.EY FIELD, MAM1N, VRIN*A

TO ThLMOV€ *uø€:

QUESTS R) P*iCAIONS SHOULD ,,Do(SstD

Vasi ng to i-i I11Nk pmi*y coMMrcEE Mebruary, 1931 37$UMI'. N.W.. *INGTO$ • 2S. ).C. NATIONAL ADVISORY COITTEE FOR AERONAUTICS

TECHNICAL 1MORANDUM NO. 608

THE USE OF ELEKTRON 1.rETAL IN AIRPLANE CONSTRUCTION* By E. I. de Ridder

The tendency in aircraft construction is tovard higher per formanc:e. and gea.ter economy. From the , aerodynamic standpoint this me:ans a minimum possible drag by streamlining,. and from the structura]viewpo,nt, .aving in weight by usag light metal. Elektron is the lightest of the light metas, andas such merits our special attention beoaus .e it meets the demand for

lighter construction. Itis impossible to go fully into its mechanical proper-

ties and chemical composition on this occasion, but i .t should. not, be passed without at least briefly describing those characteristics which are of interest to the cpnstructor who uses it.

E].elctron,. .as manufacT'cured ly the .1. G. Dye Industry, A.G., Bitterfeld,; isa magnesium-base alloy offrom 1.8 to 1.83 spe- cif'ic gravity.,. lience.a third as ligit as aluminum alloys. The rn I + .' eEg point of the metal is 625° slightly below that of aluminum. The termal expansion coefficient s. of the order of the aluminum alloys. The. absolute figares. for thermal conduo-

tivity, electrical conductivity, tensile strength, and mou1us

of elasticity (for ta:Le__see .appbnd.ix)_are 1bwe than for ai- Die Verwenclung desE1ektrometaJ..1s im Flugzeugbau From Jahrbuoh 1929 der Wissenschaftlichen Gesellschaft fur Luftfahrt. 2 i.A.C.A. Technical Memorandum No. 608 minum or its alloys, although a comparison, which takes the specific gravity into account, yields appreciable advantages.

Regarding the chemical resistivIty, it seems unfair to demand of elektron what we have been unable to achieve even with iron, that is, absolute constancy against atmospheric oxygen.

EleI:tron corrodes, forming a grayish-white film, but this corrosion does not continue as it does in iron, the oxide film forming a protective layer against further corrosion.

Figure 1 shows an automobile wheel rim of elektron with a wrought iron disk, after having been exposed to all climatic conditions for two years. The elektron is covered with a protective film of oxide, but the iron is in an advanced stage of corrosion.

The base metal magnesium is wholly passive to alkalies, such as caustic potash, caustic soda, soap solutions, etc., but ir soluble in all acids except hydrofluoric acid. Hydrous solutions containing fluoride or biohrothate, such as sodium potassium and animonium fluoride, do not attack magnesium, although it is very snsitivto chlorides.

lektron likewise is proof against the majority of alkaline- reacting and neutral, organic elements such as trichiorethylene, carbon tetrachloride, acetone, •aniyl- and ethyl alcohol and, particularly, against the commonly neutral oils nd pure fuels, benzene and benzol.

By changing the composition of the alloy, and mechanical I'T.A.C.A. Technical Me.riorandum No. 608 3 working and heat treatment, th chemical resistivity of the magnesium alloys can •be materially indreased. To ensure satisfactory surface protection, a sithple treatment has proved very satisfactory. Pickling th metal 'in a 'nitric acid-chromate solu- tion (bichromate bf potassi'in 15%, conctrated nitric ci 20%, the rest water) froth 1/4 to' 3 minutes (dpending on the size 'O the metal), followed, by washing athd drythg, i'esiilt" in . a brass- colored deposit, which acts as corrosion'reentative'. As 'in all light metals, a 'ood coat of' varnish is advisable. o give the usé of' dlektói a 'genea1 vietof its pOssible uses, we shl1 tdhch' upon the technOlogy' of thi metal. ' Elek- tron is available in the form'of dasti'ngs, pressings, and rolled products. ' ' ' '" For castings, two principal alloys are'ued: 1. AZF', whibh has a high internal workability, and l's prticular1y siiitle for parts subjeóted to ' abnormally high, temporary stredses, such as parts of a landi'nggea.x and tail skid. Thus, F'ju±e 2deibts a landing gear assembly for the Junkers F 13. Thd cross bars' carrying' the shbok absorber cord are, and havO been manüfactii±ed 'for yearsof 'AZF'metal. 2. AZG, n alloy with a high yield point and bending vibration Ctreng±h is particularlyuitedfo parts u'ojeoted to high fatigue stresses, 'such as cank cases, etd. (See airplane engine with elektron crank case, Fig. 3). Aside from the usual sand castings, chill ' and die cstiags 4 1T.A.C.A. Technical Memorandum Io. 608

are manufactured. The size and weight of the castings are about the same as for aluminum castings. The standard minimum wall thickness is 4 mm - in special cases for smaller pieces, 3 mm. Forged and wrought material is made from: 1. AZM alloy, which constitutes the most important material in aircraft construction as extruded profiles; 2. AM 503 - This alloy is malleable and is used for pipes and fittings o.f fuel tanks; 3. V 1 - especially suitable where hardness and ultimate crushing strength i.s considered more important than tenacity. Figure. 4 shows as example, the crank case in AZG metal ad the polished ad iaardeed cn shaft bearing in ecbruded V 1 metal, where the absence of bushings will he noted. This en-- gine is in mash production. All sections known .n the iron and steel industry as rolled profiles, are made in elektrQn by pressing through special form presses (extrusions). Vith the present equipment, sizes up to

30 X 230 mm for solid cross sections and dimensions up to 200 nun web heights and 70 nun flange width in profiles, as for I beams, can be manufactured. The lengths furnished correspond to about 25 kg. Tube sizes made at present have from 11 to 150 nun ou±- side diameter. Te minimum wall thickness of extruded profiles and tubes is 1.5 mm for small sections, and 2 mm for medium and larger sections. Pressings and drop forgings are made at 350 to 40000 toniper- N.A.C.A. Technical Memorandui Eo. 608 5 atures, where the material can be shaped very satisfactorily for pistons, connecting rods, rocker arms, cam shaft bearings, etc. Larger forgings, such as propellera, have likewise been. attempted quite successfully. As rolled naterial, elektron is only ±urnished in sheets, made from: 1. AZM alloy, and. principally used for supporting parts in aircraft structures;

2. AM 5O2 - a malleable sheet, specially suited. for fairings and. fuel tanks. The available sizes conform to the standrads of the Falu

(See appendix). The sheets range from 350 mm to 630 mm width; the lengths from 2 to 3 in, with the present manufacturing equip- uent. Profiles made from strip can be furnished. in from 0.3 mm to 3.0 mm gauge thickness.

Manufacture of Elektron Metal in the Shop Basically, àlektron d.oe not require melting and subsequent shaping within the aging limit, followed by ainealing as is necessary with â.luuinum alloys. On delivery elektron strip has its final mechanical properties. Appropriate annealing does not lower its tensile strength.

In principle, elektro1 should be hot-worked, although cold- working is possible to some extent. The best temperatures for 6 N.A.C.A. Teohnica1MomorandumIo. 608

th.e AZM composition in sheets are from 270 - 30000

AM 503 I! II U It 270 - 330°C

Z 3 8 II II 8 270 - 30000 and for V 1, AZL and AZ 31 in extrusions are from 270-300°C.

At these temperatures elektron sheet can be worked like soft an-

nealed. aluminum. The permissible bending radii are equal to

twice the trip thickness, for strip over 2 mm = 1.5 to 1.8

times the thickness. For working in the vise the open flame • (gas flame or acetylene with compressed air or blow torch) can

be used. The suitable temperatures can be determined by coating the

tip with machine oil (flash point about 300°C). As soon as • the oil beins to flash, the co'rect temperature has been reached.

• Vise and chuck should be heated during working. For repeated

working, as for profiles, or in drop forging, muffle furnaces

have proved very satisfactory. In rare cases the strip may be clamped in wood or asbestos chucks, where heating the latter

becomes necessary. Figure 5 shows the fuselage and engine cowling of a two-

place sport airplane made from a wooden pattern. For cupping, it is best to heat the tools to 400-500°C; the use of palmine is

advised. Parts intended for especially high ductility are made

by first welding the shaped parts and then finishing the cup-

ping. The strip profiles used in aircraft can be made by hot-

drawing. Fr straight profiles the matrices must be inclined I.A.C.A. Technical Memorandum Io. 608 7 toward. the direction of draving. Fiire 6 shows the manufacture of an intricate profile. The strip is drawn through matrices a and 'o. Both are coniected by a solid, piece e,. and the whole is tippe4 at angle a. In this process the section a is shaped into b; then it is dravm through matrices c and d, where it attains its ±inal shape. For lubrication a mixture of 1/3 hot vapor cylinder oil and 2/3 machine oi.• o .r equal parts of beeswax and mutton tallow can be used. Owing to the thernal expansion of the strips and. of the drawing tools, the matrix should have sufficient clearance (up to 0.2 mm). For tipkness- es up to 2 mm, the drawing speed is from 4 to 5 rn/mm., and. 3 rn/mm for over 2 mri. Drawing is economical for 0.3 to 3 mm strip thickness. In special cases, as for smaller.profiles, or where it is possible to cut the profii length edges, the cut-off method can be employed. Hot-working requires heatable cutting machin- ery or, at.. least, heat insulating. hardwood or asbestos chucks. The s.tahility of elektron 1netal for fairings and tanks (gas and 01,1 tanks) brought up the question of welding. It as found that , 1loy AM 503 was very weldable when a special welding flux was used. The seams themselves when hot, can be worked like the strip. Butt-welding is used because it is the only method by which it is possIble to remove the oxide film. Figure 7 shows some corect1y and incorrectly welded seams, and Figure 8 shows how the correct adjustment of the burner can be checked. 8 i'T.A.C.A. Technical Meriiorandum No. 608

The mixture ratio of oxygen to acetylene is plotted against the

strip thickness of magnesium base alloys and iron when welded.

Figire 9 gives the discharge velocity in the burner plotted against the strip thickness. The nozzle orifice is of - to 1 mm diameter. For strip thickness of 0.6 to 1 mm the oxygen feed is about 0.2 to 0.25 i/mm.; over 1 nun, it is 0.5 to 0.6 i/mm.

Riveted joints are made with the MG 5 alloy developed from an aluminum basis. The rivets have a shear strength of 22. kg/ mm, an elongation of 26%, and can be cold-driven. For low-stressed parts, pure aluminum rivets are practical. But for average and high-stressed parts the LG 5 rivets should be used. The crushing pressure in the strip ranges between 45 -

55 kg/mm2, depending on the strip thickness.

A number of structural parts, which are only slightly shaped can be manufactured cold. In exhaustive tests on possible cold- working, the following bending radii for simple bends were set up:

AZM strip thicknos 0.6 mm - bending radius 3 mm AZM 1 U II If 7 II U ll AZM • 5 11 - U AZM 2 ft 20 Aiii 503 U 0 . 6 2. 5 U AM 503 ft U ft If 7 It AM 503 U 1.5 ft 11 ff AM 503 U 2 u 20 f

A round disk of 500 mm diameter made of AM 503 soft cam-i be cold-- - if bent 25 mm, and 10 mm/made of AZM alloy.

Figure 10 shows the assembly of an engine cowling and propeller fairing, where the various parts are first welded and then shaped. N.A.C.A. Technica Memorandum No. 608 9

All development in conventional constructions in light metal until now are based on the kinds of structural materials.

The decisive factors for such constructions are:

1. Physical and chemical properties, as well as strength; 2. Viorkability; 3. Behavior of the material under special operating conditions. . . For elektron alloys it was therefore imperative to develop special construction methods.. It . is common practice to express the utility of materials in figures of merit or quality, as con- noted in Figure 11, which represents a comparstive tabulation of figures of merit for tensile, strength and yield limit. The diagram yields in natural scale the structural weights of any of these materials under tnesile. stresses, assuming equal tensile strength. The aluminum base alloys being best known, the data on weight saving was, based' on it. Elektron shows a saving in weight throughout, even i± the yield points are. used as basis.

Figure 12 is a comparative compilation of the figures of merit.for structural components with respect to their bending- vibration strength. . The given weight, savings pertain to cast aluminum and duraluminas basis. Again elektron makes the best showing.

Ii Figure 13 we tabulate the figures of merit under compres- sion and buckling. Based on a report of Wagner (Zeitschrift fir

Flügtechnik und. Motorluftschiffahrt, 1928, page, 243), we compared elektron with . duraluniin and steel. In 1iVagners report it was 10 .A.C.A. Technical Memorandum No. 608 stated that profiles and plate walls stressed in buckling, or bending constituted. about 90% of.. the.etirewing structure. One column, gives Tetmayer's.fIgures for AZM,aiioy.; the best for pressed profiles, the other for sheet.

Lastly, we see on Figure 14 a comparison'of structural coin- p onents with equal distortion stiffness and equal notch tenacity. The data given in the diagram for 'distortion strength applies equally to the shear strength, alth6ugh to a lesser extent, because the shear streses in the äonventional constructions with web stiff:eners and sheet covering ar so low that the shear strength of the elektro. is a:ip1y sufficient Moreover, the shear induced by rikreting is'taken up by the crushing pressure', which amounts to 45 to 55 kg/r1r 2 and which, bonerted to figures of 'rierit, ádi:iits of a saving in weight relative'to the other 'ni térials.

Figure 15 éhows the load test of the end ±ib of a Rohrbaci wing, based on the relative data for duralümin and lautal as, given by Brenner n the D.V.L. (Deutshe Versuchsanstalt fr Luf t- fahrt), Report No;89.' The few'changesinclude added gusset plates and geometrically larger profiles. But even with this increased volume in material the weight of the elektron rib is lower, although its absorbed ultimate load is higher. Notwith- standing the fact that, strictly speaking, the atiô of specific weight to ultimate load in -bhe diagram is" only theoretically important, it nevertheless becomes apparent what eight advantages N.A.C.A. Technical Memorandum No. 608 11 elektron metal has to offer for parts subjected to stresses. Figure 16 shows an airplane seat of elektron. Vith only minor changes from duralumin seats, the elektron chair is 23% lighter and 10% stronger. In subsequent development a more suitable type of construction was inaugurated, as exemplified in Figure 17, which also is 23% lighter and of greater strength. The manufacturing cost in both types were 4.5 : 1. For welded sheet covering and for fuel tanks, special structural methods were developed which show what may be accomplished with a material if its ovn particular characteristics are used to best advantage, particularly with respect to lower rianufac- turing cost and lighter construction consistent with safety. 'Ve have already stated that butt-welding was the only suitable method of welding. In the manufacture of fuel tanks the partitions as well as other inside s±iffeners were developed from T fittings, as shown in Figure l8b They are made of pressed AM 503 T sections, and butt-welded to sheet a. The stiffen- ers c, which may induce stresses in the direction of d, are riveted to the end flap. The advantage of this method is the absence of unfavorable stress distribution and assurance o± tight riveted seams. Figure 19 shows various inside tank fittings, which may be equipped with eyes or small support blocks for point support of the tank. Often it is necessary to use anchors or tie rod.s as exemplified on Figure 20. All other fittings are turned from AM 503 pressings and butt-welded as shown on Figure 21. 12 N.A.C.A. Technical Memorandum No. 608

a is the tank wall, b the fitting used for pipe connec- tions, c an interchangeable liners d the lock nut, and ± the tightening washer. Figure 22 shows the standardized construction of an elektron fuel tank which embodies all previo'.sly described characteristics; Figure 23, the open wing tank of a Junkers airplane; and

Figure 24, the same type of tank for.an kv'ia airplane, manufactured under Fokker license. The weight of 35 kg in brass without partitions was reduced to 17 kg in elektron with partitions.

The curves in Figure 25 show the specific weights of tanks made of brass, or other conventional materials, and elektron with respect to liter volume. Figure 26 exhibits a small rowboat, built in 1927, and which, after two years of hard usage, shows no sign of damage, even though it has not been given a coat of varnish since it left the factory. Te bulkheads are open sections, all parts were varnished before riveting, the brass berig for the rudder was insulated with wood which had been previously impregnated with tar, all hollow places where water could collect were avoided, and a tarred strip of linen made the rive.t seams water- tight. Theboat is 6 meters long, 97 centimeters wide, carries four persons, and weighs 30 kilograms.

In this connection it may be o± interest to discuss briefly the elektron castings developed and in use for years in airplanes. Thus, Figure 27 shows the BMW airplane engine with its .A.C.A. Technical Memorandum No. 608 13 elektron crank case. In high-stressed crank cases it is particularly important to avoId' all abrupt changes from thin to thick er. material, sharp curves, or localization of stresses.

TiiC extent of practical àppliatI:bn to aircraft construction and. the results achieved. bec'omb readily apparent on the Savoia flying boat with two 500 hp iott-Fraschini' Asso 500 e- gines, 'shOwn on Figure' 28, 'and. with which Pinedo crossed: the ocantwic.' That this engine has proved. successful for hyd'o- planes is borne out by the fact that. about 2000"are in practical use' to-day'. •Anothe± triking example (Fig :29) . IC the '1000 hp Iso'ttá-'FraCchini ith crank .caing, 'valv.e cov.Cr, ..cáburetor man- ifo1d,cañsha±t support,' e'tc.,:..of"èletro. Figure '30 shows a cat .l.ektron airplane wheCl,, in mas produOtiori for •the Junkers type G 31,. and.Figue:.3J'shows, part of a cast elektron wheel, standard for Albatr'os 'and' ,Dorier ai. pl anes .• '' . ' .: , , ,.,., 1 Figure 3^ is the cast elektro.n. shock 'absorber leg for Jim-: kersG .. 3I.. (na.ss production), and Figure 33, a J'nicrs t.ail.skid. Figu'e 3'4 i's an engine cowling for the Junkers. F 13, ue,d for over a year, and. 24 lighter than a duraluridi cowling.' Figui'e 35 ShoWs the.engine cowling and the propeller fairing of an :A1batros; .'Figwce 36 depicts' an Albatros biplane with prôpei1e'ii'iiig, engine cowling,' fuselage:and landing strut fáiring, 'pilo't*s seat., 'Observer's' seat, etc.., 'of elektron metal. The airl'aes made by:"theLetOv Company, .Pragtte, likewise show liberal'use of èlektron. .. ' 14 N.A.C.A. Technical Memorandum I'To. 608

Fire' 37 shows the fuel and oil tanks fo Klemm sport airplanes, and Figure.'38, a series 'of larger wing-nose tanks, as installed in 'the''Breda airplanes in Italy..' Figure. 3' shows a Junkers F 13 type.win.gtank, who2e weight,'re.vi.ously.o 'brass, was 17.7 kg', as compared to 6.7 kg in,'elektron'metal. After a series of tests on .airplane seats made by the D.V.:L., which af .i.rrie:d to lower st,ructua1 w.eight wit,h higher ultimate. load,. elekt.on• seats were. produced in series and de1iverd to. the industry.' .Varous seats ie shon in Figure 40, t,o be installed.ir,BWairpianes. ;A seat weighs3.5 kg, and withstands, an ultimate load of 50 kg. Figure, 41. hows one aileron of a' two-plaoe Raa-Katzenstein..spQrt airplane, in.u , e for over a year. A epr'esentative"exaLrpJ,e of 1e.ktron ii highly stressed structural. .orponents, is the engine,.bear.er for a 40 hp Saimson- Klerm sport airplane (Fig. 42). Excepting the four-corner, fittings and the mounting"ring, the,entire bearer is' of elektron. Figures'.43, .44,'and 45 representexperimental wing structures in elektron; .one for fabfic coverin, the other for metal covering, and the 'last wholly of elektron'metal. The possibilities of elektron metal in aircraft construe- tion 'areL enhanced 'by the marked saving in weight, 'which ranges between .10.- 30% with'repect to. the conventional kinds of mate- r.ials.used. . What this .rieans for the airplane industry regarding increase '.in,use,ful'ioad, can be seen at a glance. on Figure 46. Taking advantage of the present state of development with N.A.C.A. Technical MeMorandum ITO. 608 15 elektron metal, the industry can effect a saving of 15% in empty weight. It would mean a higher pay load which, for the conventional types of commercial airplanes, ranges between 40 - 70%. N.A.C.A. Technical Memorandum No. 608

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N.A.C.A. Technical Memorandum N0 . 608 18

sicalProprti Cs

Specific gravity, 1.8-1.83

If heat, 0.24

Melting point, about 625°C

Shrinkage, It 1.3%.

Electrical conductivity, 12-18

Coe:rficientof_Theimal_Epansion

Cast alloys (AZF, AZG):

For 20-100°, 0.0000255

II 20-200°, 0.0000271 Extrusions: (AZM, Vi):

For 20-100°, 0.0000240

20-200°, 0.0000257 Piston alloy:

For 20-200°, 0.0000250

Thermal conductivity, 0.32

The data for the extruded alloys depend on the degree of extru- sion normally obtained in round bars up to 50 mm diameter; larger profiles show slightly lower strength figures. The data for the sheets are valid for thicknesses up to 1 mm; thinner sheets show slightly lower strength factors. N.A.O.:A. Technical Memorandum I'To. 608 19

Remarks

The figures for sand cast are based on many tests. The following values are determined on sand cast tensile test bars:

AZF: yield point, 9 kg/mm2, ultimate tensile strength, 19-22 kg/mm2,

elongation at rupture, 6-10%.

AZG: yield point, 11 kg/mm2, ultimate tensile strength, 17-20 kg/mnl2,

elongation at rupture, 4-6%.

AM 503: Although the corrosion resistance Was raised at the expense of elongation, the metal is eas-

ily hot-worked.

20 N.A.O.A. Technical Memorandum No. 608

TABLE II: Tubes -. Available Sizes

Inside diameter,: 8-50 mm, with minimum thickness of 0.8 mm

It II 50. 1-80 mm II It 10 II

It It 80.1-100 U II II U 11 1.2 Outside diarneters on denland. - Dimensions below 8 mrñ ±nside diameter dn demand.

Tolerances (extrusions)

In outside diameter: 2.5% (mi.nimum ± 0.25 mm)

In insid.e diameter (minimum tolerance only) to 20 mm $ 0.5 mm ...... 20-60 $ - 1.0 over - 1.5 U For Drawn Material

In outside diameter: ± 0.1 mm

In inside diameter to 20 1 - $ ...... 0.1mm from 20-60 mm $ ...... ± 0.15 Over ± 0.15 It Due to the fact that tubes in hot pressing may become slightly

eccentric, the following tolerances in wall thickness are permissible, which also define the eccentricity

For Wall Thicknesses: 0.8- 1.4 mm ±0.2 mm

U It U . 1.5-- 2.0 " th 0.25 II It II II 2. 1- 5.0 ± 0. 5

u it II 5.1-10.0 It ± 0.75 U

It ti 10.1-20.0 II ± 11 II over 20.0 u 1.25 II N.A.C.A. Technical Memorandum No. 608 21

(O0 )(oco o'i c100i000000000Q000000 •H 10Na0(D• 0) a) NU)o00 tO'1010'-W p4 000 u4 r4r1 rrIr4r-r-I

CI) Pi - JIll 01+ U.Ie1oTj

a) SZ$ U1nUlTX'UI poS Ot[ JO UL ssa qu SSttT3 0) 11W JAO 98tS UT.SS8 JO SSOU)3Tt4 11111 JO S8GtS .io; unix ooi .xapun ou riq suo •Io3EJ.upa.xeAflaa

I 9S3 Oa JOJ UOdfl . 00J SI a3UJ9O. TT SdTJS UI ,3 - 1. mm 4 U) 0)

.rl CI) 4) 1111 01+ oq.uiui oc- e3U.IIO

a) ,c1a- 00000000000000000000000000000000 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 010 010 0 10 010 •r.4Or4NrI OOL0(0LU000C00000C000N1UOC\)rl0OO)WNN10rr-1r1r1 1 cii Q) a) a) - 0 CD N N N N 0) r 10 10 10 10 N N 0 0000000 a) Eto 000OCO00r QC(\)C ) (I ft ft * ft * * ft i . . . a s a a a • • • . ., o , a • • • • Q U) C? 00 00 00000000 0 0 000000000 U) -ft +1 -H +1 +1 - +1+1 -H +1 + +I+14+t -H -H -H-H - -H + +1-H 3) I.—' 1-4 1010 I—i 00 -i.ECD4 *** ** • . 000000000000000000000000 -4 C) 00 D

43 0 1010 00 4L0•r4 *** 00 000000000000000000000000 00 -If cii -1 - 0ii If) E 0 Ei4 r-4) ** 0 • 0000 0000000000000000000000001 E______- E100 E001010 -I E •. 00 000 000000000000000000oo0000 a ______-______31) cv, ) inCa 3 '3) - - ) . . . . a . a • a a ...... a a . a a a a , . a • . a •. .4 -•rI 0000 S000 - - iCQ101010101010NNcc,'OOa- r-1 I) )1) 22 ILA.O.A. Technical Meiiorandun No. 608

Footnotes from pate 20:

1) According to established st,ndards of Falu.

2) Sheets under 2.5 riirti thicknesses, other than given, are made on demand only. Intermediate thicknesses can be supplied in sheets of over 2.5 mm, but are not kept in stock; therefore, those in parentheses should be ord,ered only when absolutely necessary, due to de- lay in delivery. .

3) Larger widths are not available; the same applies to those marked with * ; those marked with 0 can be delivered, hut eze considered as strips.

4) These are for normal widths. Narrower sizes of greater. length can be obtained on sp ecial order...

5) When measuring the tolerance the measuring points siould be at least 100 mm from the corners and 40mm from the edges.

Translation by J. Vanier, National Advisory Committee for Aeronautics Figs. 1, 2, 3, 4,5

F ig. 1 Fig.4

' -

ii I [ Fig.2 I - j4 Fig.3

•

N.A.O.A. Technical Memorandum No.608 Figs .6,7

- b

Fig.6

(l)Wrong

Before and after welding (2)

Before and after welding r.. . -Extruded profile

'Wrong Right

(5)

Fig.?,

N.A..C.A. Technical Memorandum No.608 Figs.8,9, 10

0 •r 4 c -Valid for elektron AM 503

'Va1id for iron •rl . C i.0 Thic1ness, mm

Fig.8

+ ) •r4 H ON ON HO

,i r0 0

n J_'u '.0 Thickness, mm

Fig.9

F1 3 2

Fig.i0 N.A.C.A. Technical IerorancTurn, o.O8 Fig,ll

— — — ______-- I

...... (13 E H a)CO H Co —. ___ -- —.------I---- ti) •rl rj3 I o 'd 0 0 CO a) Cl) •rI -4 . . I (0 V) 0 ___

-4 rH

Co -- ______— _I bD .OV) o -i 0 (.0 '. ) 0) 4 [Ui Cl) l...... -MI.0 0 • (0 F-i o cc 0 CO HCl) CO r-I .1 0) H HN ______c13 0 V) N CO • 0 . • _____ Co N a) to 0) ij CO H H _____ a) ______0) — ______F-i 0 ItO 'r I 0 t' 0 (.0 I:; ..-; C) H • • • F.\ •rl to c13 0 LU N H 0 F-i CO F-i 1 CO H 0) a) i F-i ______-______-______cl—I 0 o ...... F- cc CO 3 + 0 0 0 aD a) F-i U0 cc cc 0) H V)H H b.O lxi I ______I—I ______I 00 0 LU a) .. o • . ______'-I \'\\\\\' \' \\ \\.\\ F- 0) 0 H LU H H H LU 0)

r1 f.I i1 00 to N) r

• . H H H CO \'.s. CO H

°c::o ., F-i 00 H CL) a LU C) CL) ç 0 ____ H H H H N) H I lix] ______0 0 -P-• (I 0r- 0,1 R N 0H o1bn °t a—f '-1- 0 ?) F-i•rl . 0 0 0 0 0 C - ___ __ +O)__ LU N) 02 H _—---.— __ -__ IN 0 C)H N.A.C.A. Technical Memokndum No.608 Fig.12

I I I I' 0) a) 4-, Cl) 0) o 000 0 F-i • '.-•1 CL) U) LC) N C\2 -uD H H

a) F-i a) 4-, I- CO Cl) ____ 000 Cl) Fl o. . 0 0 CQQ U) Cl) H •r1 4' C-LO V) C\2 H +D 0 F-i cd ;-i cd F-i ,0 Co - - - ______o -3 00 0 0 Fl H •r-1 O3HOLU 'zJ 0 0 kCO Cl) H Cl) Fl :j(o a)

I I I F-i 0 CH -i 00010 0 CH C E C') H H N) r-1 F-i a) __ -______1:1 00L) 0 0 ______Fl • o ODsO H 0) ______0 F-i H H H - H . H -______CO C]) F-i 00 LU CO ___ 1LI cd HH Cl) r Fl 0 bB LO '& -4-t00tf) 0) 1.0

• a)Lc) ON 4 IC) H HH C') sji 1:1 I

Cl) .-'} ?-fl 0 o j4 CF 0 CO 0 4 F-i C') 0 CO 'CO C') H Wi H H 001

N.A.0 .A. Technical LemoranduM NQ .608 Fig.13

NN0OH000O0N H 10 00 0C)N 100 H 00 .0 ) 0 a) 10 H (0 'Co 0)10 0) I I N c I 0)10LrHN)H 0)0)0)LO10NcOCO

LdrO 0'J CaCH )U4r-1 0 P -. I I I I I hO Ca hO CD• H • r F-i b.O H cv . •0 to cv UTWflTn \\ o hO a) ?- ci U0.1 I I hO 0+:) ______r4 -U) •r1 i d Ii bDH H rn H o ,14.r-1 r-4 o CH 0 I I I o LOO o •o LO N •H a) 0 •HTJ c Q 1a) UTLUflTJflG H •-I H U . 4 :1 (dF4 0 rj H F-i+' .r3 Q, (5 Cd i4 to I F-i t1Q) Co Cd I I I CQç 0I r hO Ca C)1 -______cv, p1 r(j a) L) TL__ •---.F-I 0cv ini- 0 rI ,ir4 0 _•O0 a) •1 0 o II ____ -10H F-i ;i C) F-i J0GTL _____ bOHU) 0 O,4 cv' C) _fl---- I • I I I o0o + tHcd 00 U)-. •rI OrHCO 100 ,hD F-i •rl 0, -- U) hO0 0 ______hO 0 ICQ : . . i-i 010 010 4-i F-i F-i 0 U) U 0.1 C ______U) -fH +H 00W .)4a)4a Ca 1a) (DO) 0)0) a) rH+H4 D F-i I I —1- I

F-i bOa) T CC SL___ UTtflrtrLP CCI 0 hO CO ' a UO.IfCTcT _____ 0 ?Ot H F-i OE SCITTO.1CT CPflJLX[ Cd 0 00 II d 9-i ciJ 0

-______f=I 101 (3 r 0 LI) 4 10 10 H 0 N.A.0.A. Tecinica1 Memorandui No.608 Fig.14

-P i) o IC) _____ -p H 0 C!) ci) 0 0) H ______o 0 4 tO 0 0) 0 Cl) U) ___ I ______'ri 4-' 0 0 4-) 4-)1 o o Co 0H 0 • 0 r4 H ti ci) -i N ki U) rd •4-' i ______- Ok 0 N - 4-) •H+ 0 0 0) ______'H +'4 0 0 k ci) 0' H U) OH N ii +'ci H ci) a)— - I I I I 4-) 'rI 0 LU 0 LU 4- H U) H H 0 0 O •' 0 ct TpTt;osnripo 0 0 co i .HJ 0 j . p p H'd 0 H'd O j 'r4O' i.H i) 0 k.r-I O U)11 ?- 0 ci) 4-' ci) -4 kCQ ______-p •r4 'H ci) IC) ______H 0 c) ct3 fl 0) 0 0 H 4-' i H C!) •rl ci) 0 ______k bU (1) k LO LU rI -p + 0 H N U) IC) <1) ,H U) OH H H H 4r I bU •rl • . U) H H 0 •H -p -p Tou. _ /ooi Oa)C 00 -Pci) N.A.C.A. Technical Memorandum No.608 Figs.J51S,17,l9,2324,25 1ekt ron Ahunixrnm alloy,1 'A1umin12xn alloy,2 Specific weIght to u1timate 1oad .2OQ I I I I I I I

...-.....

cv2

Fig.23

N.A.C.A. Technical Memorandum No.608 Figs.I8,20,21,22

ho odi Ij< \\ Q) U ki d - • - ___ U] ho "-i 4) .3j.-1 0 r I

-4 114

4.) • 4) •r4 0 U) a) oo U] I 0 a) F' '-I 0 U 9-. 4 U) -•- ho UI '-3 U r-4

p.' .Q) 0(1)

00) o\\ :

'0 *0 1(1] / ,f \\ Cl) € / L * 'U) w Q) (1) '1-4 0 4.) 'oOo. • rI •,-. E 4) • -4

.1 c14 0/' - .1-I 4.)

p.4 NeA.C.A.Technjcal Memorandum No.608 Fi6s.26,27,28,29,30,31

-t . --. W

Fig.28 FIg .26 •1•••

Fig .30 U

N.A.C.A. Technical Memôranduir No.608 Fis.32,33 ,34,35,36 Flgs.37,38,39,40,41,42,43

N.A.C.A. Technical. Memorandun No.608 Pis.44,45,47,48,49

pI AL

Iij

Fig .49

V Fig .48 N.A.O.A. Teciinical Meiiioraiihini ico.608 Fig.46

Dornier-Merkur Total weigit 6000 8000 4500 3600 Empty weigIt 5903 ____ 4400 2400 2150 Useful loai ____ 2700 ____ 3600 2100 1450 10 13 10 6 15% saving in emty weit b8b oGO 3O 32 1 Thase Se '- 7 8 4 in pay 1gers 61.5 I 40.0 63.0 1 70.0

22 20 18 16 14 - 12f - 1:111 Fig.46 Lici-ease in usefil load when using elektron.