3*3-3-^ 4, A STUDY Cf TEMPERATURES ATTAINED IN A DUMMY AIRCRAFT WING DURING THE SUMMER AT MADISON, WISCONSIN January 1943 RESTRICTED CLASSIFIED DOCUMENT This document contains classified informatior the National Defense of the United meaning of the Espionage Act, USCJ^"K'J8|^52. Its transmission or the revelation of ^StjBftltnts in any manner to an unauthorized P^tAa is^vdrubited by law. Information so classified m^Warnparted only to per- sons in the military jgflfft|ls^r*Services of the United States, appropriate* qyvif%n» officers and employees of the Federal fifrtffllWW* wno have a legitimate interest therein, a^jrKiEmAd States Citizens of known loyalty and ^fj^ p f Wfr i % who of necessity must be informed the* m \ | THIS REPORT IS ONE OE A SERIES ISSUED TO AID THE NATIONS WAR PROGRAM No. 1343-B UNITED STATES DEPARTMENT OF AGRICULTURE FOREST SERVICE FOREST PRODUCTS LABORATORY Madison, Wisconsin In Cooperation with the University of Wisconsin a 3i. iy or I. .•:. -,.: attains ::: a zwiTf aihc^aft •'.'!.::- r/:--.::;; :-.z juiuzr Al . -ft-/- SO; , .-.— By F. I. EHOWKE, Principal Chemi I DO!. 7 LAUGHNiH, Associate Technologist BRUCE &. HXEBIBK, Associate Technologist ?EHT 0. FLEISCHER, Junior Fere L« Ls report presents the detailed results of a study of temper attained in a dummy wing. A summary of these results is given rest Products Laboratory Mimeograph Mo. 1343A. Introdi The wings of aircraft enclose air spaces that are vented side atmosphere only through a limited number of very small holes that little or no circulation of air through the spaces when the craft on the ground. For that reason, higher temperatures are attained w wings and within the plywood wing coverings than those pr ir- rounding atmosphere. The use of eamouf. of dark c r l-. to the absorption of heat from sunlight and the at: temperatures. The experim- described were made I the magnitude of the temperatures so attained. ' i' r, about the relative temperatures attained when the ' rfaces are I ed . paints of different -~lors and different reflec radi . attempt was made tv determine temperate prevail In an aircraft win,- flight and, w of that limitatl : , the dun ^sed resembled an aircraft • of 1 i skin of aircraft plywoc led around a I to the extent of following aircraft proportioning and ries of reports issv. o r the Hesull re re- *ed are prelim: may be red as ado' al dat :.ies aval lab 1 . ; 3 -1- Details of Construction of Dummy Vint: The dummy wing (fig. l) was mode with parallel sides in such a manner that "both edges simulated leading edges having a 2-inch radius of curvature. This type of construction was adapted for two reasons: first, it was simple and convenient; second, it permitted testing a maximum number nf treatments of the leading edges, in which the plywood is sharply bent or glued to shape. The over-all size of the test structure was 4 by 28 by 06 inches. The frame- work was constructed of o/4- by 4-inch solid spruce stock which was used for the spars and all of the ribs. All ribs other than the end ribs were bored with four 2-inch .lightening holes. a skin was 3/32-inch aircraft plywood of 3-ply construction, applied to the framework with the face grain parallel to the spars. Three species of wood — birch, yellowpcplar , and mahogany — were used in the face plies. Some of the details of construction, together with the arrangement of the test sections and the numbers assigned to them, are shown on the sketch in figure 2. The sketch shows the division of the dummy wing into six test sections numbered 1 to 6, starting at the left. Each section consists of a central portion B, covered with panels of flat plywood, arid two leading edges, A and C, covered with curved plywood. Panels on the tops of the central portions are designated B]_ panels and those on the "bottoms Bg panels. The plywood skin on sections 1 and 2 was of yellowpoplar, that on 3 and 4 of mahogany, and that on 5 and 6 of birch. Holes l/8 inch in diameter were drilled in the four corners of each of the bottom (Eg) test panels to simulate the vents in an actual airplane wing. Holes were likewise drilled at 8-inch intervals in the flat bottom faces of t he le adi ng edge s . Two glues, Butacite 4644, a thermoplastic polyvinyl butyrate resin glue (a liauid glue); and Tego, a high-temperature thermosetting, phenol- formaldehyde resin glue (film fcrm) were used in the plywood construction. The leading edges v/ere made by four different methods; 1. Flat plywood bent dry and nailed in place. 2. Flat plywood bent after soaking in cold water and dried on a form before being attached to the framework. 3. Flat plywood bent after soaking in hot water and dried on a form before being attached to the framework. 4. Plywood bag molded before being attached. Some of the pieces of flat plywood for the top and bottom surfaces of the wing were nail glued in place, leaving the nails in place, whereas the others were nail-strip glued, thereby leaving only nail holes. Details of the plywood construction, including the type of glue, the method of gluing, and the method of attachment to the frame, are recorded in table 1. • -i f ** * - Eight copper-cons tantan thermocouples of No. 30 gage were installed in the dummy wing. In each case the thermocouples were placed at the cental' Mimeo. No, 13433 ~2~ • the 1" .are center sec- t thermecfuplea were ailed ns 1 and 6, .-.11 I -;d before installatlcn t found to read 211 c F. i:. boiling wa1 I , s abcut r boil: water at the elev of iiadison. The If I ;rmc- uplea in section 2, 3, 4, and 5 was as fcllcv. section 2: One in the upper glue line r : One in the air space between panels 23]_ and 2^2. 3 in the btttom lue line «f panel 2 section 3: 0:. the air space between panels 3Bi and 3I?2. In eectj 4.2 Oiie in the air space between panels 4E^ and ^B^. section 5: One in the upper glue line of pan^i b3^_. One in the air space between panels 5B]_ and ■ in the bottom glue line cf panel 5Pp. r. more thermocouples were Installed after the dummy v . as asse blied; sne (dij - camouflage paint) was taped - face «f panel .d the other was suspended by string about 6 inches below panel 31 the shade. The thermocouples installed in the air spaces w: ./ere placed about l/2 inch from the top (3]_) panels* 7 are ok arly shown in the end view <*f the diagram given .:antan lead was str - bo thf opening in section 1 and ocnstantan leads were extended froa couple . Lvidual copper wires were led from each thermc :e • L. At 1 Dint, 20-foot ex 1 ^-pper ai con an wires were soldered to the respective leads and all c: i into a cable leading te the atentis ber. Finishes A , 1 1 I -> d : ~ ' . . •-■ 7>. ;... ... v "V i . . ie wiring wa: Leted, the in1 o « the if -On fi g sys* I used I the interior ■■- . Amoo ly these «»f , I , | " I -.ed. applied by bru 'ay an object is size. St ; and 3B wer- ear sealer lu: . which was followed • _^ter by a ;c ized sealar (l-l/2 am paste to set. r). Seel b 41 and . ;oat« of I . ar s ©a- rdboard were stapled « ber 3B rib (fig, l) for the purpose of dividing the interior of the test strud into two "ate co... pertinents. The bottom test panels were t l< n •• LI Into Lace on the frame with l/ 2-inch wire brads. The exterior finishing systems were next applied, as fol o : Tor yellowpoplar and birch, 1 coat Tuf-On No. 74 clear sealer, 1 co: i Tuf-On -.'o. P-40 primer surfacer, and 2 coats Tuf-On ITo. 261 dark oliv loufl; ge enamel. Tor mahogany, 1 coat Tuf-On i T o. 74 filler, 1 coat Tuf-On No. F-40 primer surfacer t and 2 coats Tuf-On ITo, 261 dark olive drab camouflage. Most of these were fast-drying finishes designed for rapid reduction work; it Was hence necessary to reduce them with kerosene in order to a; 1;~ them with a brush. Exposure, of the Dummy '''ing The dummy wing was then ready for exposure. Accordingly, on July 1, 1942, it was mounted on a hinged supporting rack or. the south promenade out- side the main ?orest I-roducts Laboratory buildingj with the north end about 2 feet from the building. The dummy wing was mounted so that the spars Tr ere in a north-south line and the section sloped to the south at an angle of about 7° from tne horizontal. Phis angle was selected because it was thougnt to be representative of the iuaximum dihedral for a modern plane wing, Naturally, since tnis angle was constant, the maximum angle of elevation of the sun de- creased from day to day. Starting July 10, temperature readings were taken at intervals varying between one-half and 1 hour from 8 or 8:30 a.m. to 4:30 or 5 p.m., except on rainy .ays, when fewer readings were taken. Attention was also r iven to the recording of the weather, relative humidity, anc wind velocity. Daily readings were taken until August 24, e readings for several of the more representative days are recorded in table 2. In this location, the maximum angle of elevation of tne sun was about 76°, at 1 p.m., C.'C.T. , on July 10> The glass architectural panels of the Laboratory building directly abeve the dummy wing reflected some light on i1 between 11 a.m. and 3 p.m. This condition undoubtedly added somewhat to the total radiation. The temperature readings recorded on July 10 in this loca- tion arc given in table 2. It should ce added that the reflections from the aforementioned glass panels were somewhat spotty and the inconsistent temper- ature readings for this day are attributed to this circumstance, Trom table 2 it is seen that the maximum temperature of 184° T. was recorded for thermocouple l T o. 1, which is located in the top glue line of panel 53-j_. This reading was taken at 2 p.m., at which time there was no ap- preciable wind, and the sky was clear. Mimeo, do. 13433 -4- It elt th« ■ accv:- I ad com beat r soul were; erected further awa;' fro.. Id- re reflection from the t structure was moved 15 feet I -g to lta resent location. (Pig, • . : . Lson of the temperatures recorded 11 and July 17 ir Ln . Both of there days were very clear; nowpver, the 11th v diet i nereas t..e 17th was defi iltely r ' "re recorded on July 11 was 175° F. at 12(45 • '- - . the top ^lue line of section 23. ^t this time the sun was learly best elevation, aiid ir temperature in the shade was Zhe maximum lue-line temperature on July 17 '.•.•as only 155 e T. (at 12 the sa.-e thermocouple ) although the air temperature in the shade i was 94i° I. Tnis would seem to indict but face temperature is \ fectei. the velocity of air movement over surface, A study of the readin . en July li results in the furtner cc elusion that t.'.e interior finish has an effect on both the top and be temperatures, as well as a slight effect on the air tempi r ture Lo8ed s^pace. The temperatures for the I .ue line in the sectir. .ted .. the insii . aluminum were slightly, but consistent , ligher than r. corres oratures over the clear ; rould be expected, since aluminum is a good reflector, the bottom skin temper.-/ tures were consistently lower i .ized sections than they were in the clear sections, air temper tures in the aluminized sections varied from to 3° I. lover I those in the clear sections* The above observations are supported by the data recorded f er .•.ays. Included in table 2 are the temperature readings recorded ust 11, 13, and 17. A comparison of these shows the effect oi and clov. on tne ri 1 tive temperatures. test shows that, under the weather conditions - i Wis., for those days, other then July 10, designated in table 2, 11 98- sible to attain a temperature of 175° J; in the top glue line of I finished with the conventional dark olive drab camou mum angle to og surface of only 75° and an outside air temper of 85° P. Cra^. a TJelaminati'v. On July 11, the second ay of <::■-. osure, a craei. i. the i :uid the face ply of veneer between sections 6B^ and 6 3 was obeerved, two sections were of birch , tacite .^le l). Apparently , • osure to a : re above lf-"C c arc softened the ^lue and allowec. ply of veneer - ink !he crack is e J . 3B Although cracks developed in the plywood skin f ,lued wit! tnermo setting glue and 3utacite 4644, they were far more Bneral re severe where 3utaeite was used. Par "better results were obtained with nail-strip gluing I Lth plain nail gluing. In the case of the latter, the nails soon worked out su ficiently to crack the paint coating and perxait the ingress of moisture, which ultimately led to cracking aroun.t the nails. On the other hand, the sli ressions left by the withdrawal of the nails on the nail-strip glued panels did not rove a source of cracking. Figures 4, 5, and 6 snow different types of breakdown of the skin and finish. Moisture Content of 'food 7 ''iti-.in the Dummy 'ftr^ The variations in temperature in the air space within the ; -'ing caused corresponding changes in the relative humidity within the enclosed space which tended to set up fluctuations in the moisture content of the wood. Protective finish on the woo 'I surfaces should reduce the extent of variations in moisture content taking place within short intervals of time; but no finish would be expected to prevent changes in moisture content under successive widely differing conditions which persist for a cousiderable le: I of time. To obtain preliminary data on the subject, arran ; ,e...er.tc were made to insert two small pieces of spruce, one finished and one unfinished, in the air space of section 5 of the dummy wing in such a way that they coulu be re- moved, weighed, and reinserted periodically. The specimens were taken from braces in a rib from a Fairchild trainer plane. They bore a generous coating of clear sealer which is understood to consist of two ap lications of Tuf-On iTo, 74 sealer. The coated surfaces exhibited a full, uniform varnisn ^loss with numerous "runs" and "beads" where the coating was exceedingly thick. Frcm one specimen the finish was completely removed by planing off approxi- mately l/64 inch from each face. The specimens were then cut to such length that each contained 0.38 cubic inch of "ooci. The dimensions then -'ere, for tne specimen protected with finish, l/4 by 5/l6 by 4-7/8 inches and, for the unfinished specimen, 7/32 by 9/32 by 6-l/8 inches. The cut ends of tne fin- ished specimen were given three coats of Tuf-On Jo. 7^ sealer so that all surfaces would, be protected. Toe specimens were dried to constant weight at 105° C. and weight L. One end-^r.in end of each specimen was tx"en fastened by means of a small nail, the weight of which was recorded, to the center of a rubber stocper, which in turn was inserted in a hole drilled in the end of section 6 of the du wing. (Fig. 3). The specimens therefore hung freely in the air space of section 53. The oven-dry weight of the unfinished specimen was 2.701 grams, th of the finished specimen 3.047 s rams. After the portion of the work described in this re ort had been completed, the specimens were brought to constant weight in ; room at 65 percent relative humidity and 30 6 F. The unfinished Mimeo. ITo. 13433 ~6_ specimen weighed 3. 06-. , representing a moisture content of 9, percent. I Lnished specimen weighed 3.305 grams from vhich, i- it likewise contained 9, rcent moisture, the weight of dry wood vas com- • ed to be 2.635 grama ana the weight of the finish 0.^12 : ,rams. It view of the obviously thick eoating • lied *nd the of .. left on tue surfaces of the s>ecin .is weight of cc seems : .te re; _e. For purposes of calculating moisture • • ■ ■rved during these experiments, it was 1 '.-re as. * I niched B ec- 1 2, 335 r- Lned constant in weight under .-'11 conditio St the nven- Iry condition whe 11:30 . . r. July 16, both the finished and unfinished specim* began to absorb moisture, By 8 a.m. on Julj' 20, the ten :hed a moisture content of 5.5 perct rrimen one of 2.4 percej . -he air temperature outside v/as then 68 c 7. ■ within the dumoy wing 63° F. Dtiring tJ ide U bure reached a maximum of 87° I. and the enclosed air space 140 c F, As a reev I , - Dntent of the unfinished specimen fell to 5.1 perce. at of hed specimen continued tc rise throughout the la; , re- . er- cent by 5 . . Durin the next 7 days of amcl same weather condil ;lear sky), the moisture content of the ished specimen alt increased during the night and dropped tc a minimum duri. oerature within the air space scared. The maximum moisture coi.te served .ring this period was 6.3 perce;.* I mm 4.6 pel 1 specimen was clearly in fairly close .re equili its , i fluctuated as much as 1.1 percent in mcisture coj tween mor -.-• -•. . ently t :^e to rough equilibrium within 2 days after it v/as .lace:. finis lowever, required 6 days sach closei rough equilibrium with the environment to exhibit a sli re 3 ntent between mor and after continue be ..crease d . daylight hours when that cf - . -imen fell off. On July 22, for example, when the moisturi unfinished specimen at 8 a.m., 4 p.m., and 6:30 . . as 6.3, . . oen1 ectively, that of I 3.7, x. , ad 4.1 sent, respectively. 3y July 2! aver, the fini -ed . ■ rcent moisture content at 8 a.m. and dropped sli ... ture content of the u shed spec about 5.1 percent. I . . ly 27, I Led specim thin 0, it of e • us unfinished .3 percent for the weather had remained unchanged for ier day, they pre ve come tc : Gture sture conte it was not del it • decimal place \ jf the spec • cr. July 25 was a Lac ' 3 ' . ly tc Bhow *re di r .. • 1 tee, • •. . 1343B The next 3 days, July 38 to July 30, marked a ch or irom clear to overcast skies, with much lower maximum temperatures wit] U I uaimy win Ln the middle of the day and less change in relative hu. during th€ i r; \ Both specimens responded to the change in weather b; Lng in moisture content, but the unfinished specimen reacted sooner and more markedly. By 3 a.m. en July 31, the unfinished specimen reached 6.5 percent ', the finished specimen 5.42 percent moisture content. July 31 was a clc : day with a maximum temperature within the dummy wing of 146° ?. at 3 ,.m. a sharp drop in relative humidity during the day. As a result, by 4 — *. moisture content of the unfinished specimen fell off sharply to 5.7 percent and that of the finished specimen to only 5.39 percent. August 1 and 2 were again overcast with the unfinished specimen gain- ing moisture more rapidly than the finished si/ecimen, but August 3 to August 5 marked a resumption of clear days with soaring temperatures within the du wing and low minimum relative humidities. At 8 a.m. on August 3 the unfin- ished s jeciiaen contained 7.5 percent and the finished specimen 6.75 percent moisture, but both specimens lost moisture during the day, tne unfinished one more rapidly, until at 5 p.m. they both reached 6.56 percent, agreeing in moisture content for the first time since their insertion in the dummy wing, In 9 nours the unfinished sv.ecimen lost 1.0 percent while the finished speci- men lost only 0.2 percent of moisture. On August 4, a still warmer day with relative humidity between 32 and 42 percent, the unfinished specimen dropped 1.3 percent and the finished specimen 0.6 percent in mcisture content in a space of 6 hours. From 11 a.m. on August 4 to the early mornin^ of Augv.st 6, the finished specimen contained more moisture than tne unfinished one. August 6 was cool and overcast and the finished specimen contained less moisture than the unfinished specimen throughout the day; but on August 7, a bright, warm day, the two specimens again agreed in moisture content at 11 a.m., containing 6.3 percent. This is a trifle below the moisture content of 6.56 percent at which they agreed the first time. For the rest of August, overcast days brought the moisture content of the finished specimen below that of the un- finished specimen, whereas sunny days caused the finished specimen to retain more moisture than di." the unfinished specimen. During August the unfinished specimen fluctuated be Ween 7.5 anc 1 5.4 percent moisture content, a variation of 2.2 percent, whereas tne finisher specimen fluctuated between 6.8 and 5.7 percent, a variation of 1.1 percent. In both cases, the fluctuations for the period centered close to an over-all average of approximately 6.5 percent moisture content, that is, the finish failed to alter significantly the average moisture content of the weed but it cut the extent of fluctuation above and below the average about in half a greatly slowed the rate of change frrm me level to another.-- The observa- tions in tne dummy wing were continued through the fall and early winter. As the intensity of sunlight and the length o f day decreased, the specimens steadily gained in moisture content until by the middle of December they reached moisture contents of ap p roximately 15 percent. , . -The 6.5 percent average moisture content about which the specimens fluctu- ated is much below the moisture contents reported for airplane woodwork in table 3-4 on page 22 of the "Wood Aircraft Fabrication Manual. •' The cU in the Manual, however, are for woodwork in equilibrium with outdoor condi- tions uncomplicated by enclosure in spaces raised to the high temperatures that prevailed within the dummy wing during the midday hours of clear days. Mimeo. No. 1343B _p_ true that th< spec: . efore inser* ..em in t u dummy wing reduced at the ure cc at which th subsequently ccue tc uilibrium In an a r .. "en relative hui r ture, "he:, equilibrated at 65 per 8 F. at the hey attained only . Is ture .tent, whereas the equilibrium moisture content for normal wood under this condition is considered I r^ximately 11.5 pea . I ave been started in whi ^imens wer^ not reduced * inserted in a dummy wi.\ . -'I'i'ect ^f deflective P^wer of the 3ir.ish en Temperatures a~ :; :..^d in the er objective of this study involves s det- rela- • on between -earperatures attained within the . rared reflec* c =r of the exterior fini . A sec .. r as designed for use as a test frame In t.ie center panels at will. This arrangement was designed to permit the testia vral f .items simultaneously. "ruction is very similar to that of rst dummy wi.. differ only in length. Its over-all size is 4 . stalls •.: are shown in figure 7. The ribs and spars vere again mad - 3/4- by 4-inch solid s race. The ''skin'' (e><~ I center 3/32-inch mahog, >d of aircraft grade, made Bsed Lic- resin glue. hogany Lywoc ' was used to cc I re frame except the center anels, 2 ?re replaceable and are mare of 3/3; bended with Tego glue. The leading edges were made by scald plywood in hot water for one hour and permitting it to cocl er- •; ieces were nail-glued in place next mo] uples vere laced in the center of the inside birch test panel, ■•.. r - nice rib-cap l/2 by 3/8 ~cy 1; :ed perpendicular to the face gra i I .el. ad- dition, th( r les were suspended en str3 of eac. p and b I . test panels. Two thermocouples were als r placed upper and lower glue lines of "est se 1. a of tr.o uples, re, ar table 3. relative position rf ea~ le is . s of the test sections and the inside ~ test • • 3 brus: : :- -. 74 clear sealer. - .. .- received 2 scats of the . 1 - ?re ribs. > top and were <*d to the te . 6 dlf top and bol Barne Bt sections are as folio Section 1, 1 coat Tuf-On Uo, 74 clear sealer and 2 coats ryroxcote #14-109 camouflage olive drab (10 percent infrared reflectance). action 2, 1 coat Tuf-On No. 74 clear sealer and 2 coats ryroxcote #14-100 camouflage olive drab (50 percent infrared reflectance) » Section 3, 1 coat aluminized Tuf-On To. 74 sealer and 2 coats ryroxcote #14-109 camouflage olive drab (50 percent infrared reflectance). Section 4, 1 coat aluminized Tuf-On So, 74 sealer and 2 coats Pyroxcote #14~109 camouflage olive drab (10 peicent infrared reflectance). Section 5, 1 coat Tuf-On To. 74 clear sealer and 2 coats Pyroxcote -.35 blue-- ray lacquer (5 percent infrared reflectance). Section 6, 1 co^t Tuf-On To. 74 clear sealer and 2 coats Tuf-On or&nge-yellow enamel '.'o, 173 (said to nave about 80 percent infrared re- flectance) . Tith the exception of the finish coats, which were sprayed, the finishes were ay ; lied by brush. Topper wire (24 gage) and constantan wire (30 gage) extensions were soldered to the thermocouple wires and strung from test section S through small holes in the cardboard separators to an outlet in the opposite end of the test structure, The edges of the ribs and soars were then coated with a commercial latex manufactured by the General Latex and Chemical Corporation for the purpose of making water-tight joints without using glue. The test panels were laid in their respective positions and nailed in place with 1/2- inch, cement-coated nails. This second dummy wing was set up August 24 on the south promenade of the Laboratory on a hinged supporting rack in such a manner that the spars were in an east-west line and the surface sloped to the south at an angle of about 15 c . (Tig. 8). r-rom August 25 until September 5, temperature read- ings were taken at approximately 1 hour intervals (on some days readings v:ere taken every half-hour). The temperature readings are not so consistent as might be desired; they '-ere found to be very sensitive to changes in the weather. It took some time to determine and record all of the temperatures, and the mere passage of a cloud before the sun had a pronounced effect on the temperature in the test panel. deal temperatures f*r two different days are recorded in table 3. The thermocouple numbers 1 t* 6 give the temperatures at the center of the interior surface of each top panel; numbers 7 to 12 give the air space tem- peratures, and_xuimbers 13 to 18 represent the temperatures at the interior surface *f each bottom panel, lumbers 19 and 20 represent the temperatures in tne glue lines of the top panel in section 1; through an error, however, it is not known which glue line is represented by 19 and which by 20. This can be determined when the panels are removed from the test frame, but it is of no consequence because the same temperatures, within the limit of error of the measurements, were observed in both glue lines. Moreover the close Mimet, ho. 13433 _10- . . , and 20 indicate? .slip ten ture was attained in the second Lue line between lywood an La Lue lines of Lywood covering. 1 interesting observations ea .ade from table 2 ! • for August 26, it is a-ppare. . . and 5 ...... times at-wh: ;] th< angle of the cun was s^ lev: It wa:: tempi vi ture8 throughout the dummy wing struct r rly ecially true -when the outside tea -re was low (about 7C° ?,). comparing the temperature readings of the iples 1, 7, and 13, of . , and 14, ^r of any similar series, the relation between the temperatures at the top, in the air space, and at the bottom, respectively, (all i:;teri A r -faces ) of a panel is obtained. Com -f the ten thermocouples 1, 7, and 13 at 1 p, ... oi Aj list 26 shows .that the temperature at the bottom panel was 12° J. lower than that at the top panel, and the tem- perature • air space was 5° lover than that at the top panel. Headings of the same 3 couple a at 1 p.m., on August 28 show a difference of 2 between I p and bottom panels. As the dummy v . , this dif- ference gradually decreased until the temperatures were practical J same roughout the structure. A comj risen of the values in table 3 for k fi- aly that the clive urab finish having 5C percent infrared reflect i ro- dueed lower temperatures than the finl K.perce. reflectance. Again, this difference was ~ost -marked .. was at its - eipv?".- . •eat difierence in temperature resulted from the us* aluminized sealer under tne condil - tered in this Close eing tem ■ ere .recorded by thermocouples 1 and 4 for tne 1. percent, reflective paint over clear sealer and aluminized sealer, respect Similarly, closely agreeing temperatures were Les 2 a 3 f 50- - reflective taint over ~lear seal? Bealer 3t V "Tuple 5 recorded the temperature at .1 5-percent ref st - squer. ratures were with the readings- of I mple 1, it v . ie-gray 1 ^duced si he 10 ] i refiectant olive drat t. The - air space I res (c LI and 7) and betwe • emperatures at th : ^m 3U ;les 17 and 13). . e-yellov enamel pre , as well as r space, is e. •-11- Table 1. — Detail? >f plywood gluing, forming, attachment, and interior finish for v a r ious wing sections Section : Plyv:ood : Glue : method of {Method of : Interior number : construction and : B] ecies : gluing and : forming : attaching : f ini sh U ) :3- ply yellowjoplar :Tego :Press, bent : fail : Hone '1/ 40-inch face and :dry (20 ; glued :back {percent :l/20-inch core : moisture : content) 13 ) :( Forest Products : Laboratory manu- :Tego :Press : LI : glued : ne 1C ) : facture) : lego : Pre s s , ho t (water bent LI : glued : Hone 2A ) :Tego stress, cold : ter bent : Ll-etrip : ;ed : : ae 23 ) :3utacite : 4644 :.^ ress : Hail- strip 3d : Alumi num 2C ) :3utacite : Bag melded {Hail-strip : - ae : 4644 : glued 3A ) :3-ply mahogany rTego [Press, cold Hai 1 : done 1/40-inch face and water bent 1 led ) l/ 20- inch poplar Tegc : Press Nail glued Alumi num 3C ) core rTego Press, hot water bent Hail Ho 4A ) (Commercial manu- Tego Press, cold Hail '.'"ne facture) water bent glv • 43 ) Tego Press Hail-strip 'glued Clear 4C ) Tego Press, bent dry (20 percent moisture content) Hail glued : ne 5A ) : 3-ply birch j Tego Press, bent Nail - ae l/ 50-inch face and . dry (20 : glued : percent : 1/ 20-inch core : L 3 ture : oo. .tent) : 53 ) : (lorest Products : Laboratory ■janu- : Tego : Press : : blued : Clear 50 ) : facture) : Tego : Press, hot : water bent : dai 1 : glued : Hone 6A ) : Tego : Press, cold! water bent : dail glued ae ' 63 ) : 3utacite: Press : /ait strip: 4644 : glued 60 ) : Butacite! 46^4 : Ba molded : Hail : slued : ivlmeo. do. 13433 Tabla 2. Taapwralora raadlr^i In duaajr win* on dajra aa.aolad to raprwaant dlffarant tjplcal waalner condition. :5Bi lop :&lua Una 5Bg boltoa ilua Una 5B, air apaoa *B, air apaoa 5B» air • baoa ?B. air apaoa 2B, bolloa ilfia Una Jalj 10. 19*2 81 00: Cloud; 1 75 10;00:Claar-no wind i 1*1 10:30: • • ■ : 1*9 lliOOi • • • 1 157 11:30: " ■ ■ 175 12100: • ' • 1 165 12:30! • ' • 1 172 llOO: • • • 182 1:30: • ■ • 1 170 2:00: ■ ■ ■ 1 18* 2 1 30 : • " • 1 173 3i00:»artly loudjr 1 158 3i30: • •lOOiOlaar • 1 156 1 150 ;uUf 11. 19*2 6:30iCl*ax * allll : 108 9:30: ■ • 1 127 10:00: • 1*2 10:30: * 1*6 11:00: ■ 155 11:30: • 160 12:00:911&hl hat* : 158 12:*5: ■ 172 2:00: • 165 2:30: ■ 162 }:00: • 160 *:03: • 1*9 5:00: • 129 7:15: ■ 93 Juljr 17, 19*2 8:00:Cl«ar - wind : 102 8:30: ■ ■ 1 109 9:05: ' • : 117 9:35: ' ■ 1 132 10:00: ■ ■ : 133 10:30: ■ 1** 11:00: • ■ : 1*7 11:30: " 1*7 12:00: ■ 155 1?:*0: " 153 1:00: • 1*7 1:30: * 150 2:00: ■ ■ : 1*9 2:30: • 155 3:00: ■ 151 3:30: ' • I 1*3 »:00: ' ■ 1*5 *:30: ' 1*1 Aunuat 11. 19*« wind 8:00:Claax-ne 87 9:00: • ' 106 10:00: ■ ' 125 11:00: " ' 1*3 12:C0: ■ ' 1*8 1:00: • ' 157 2:*5: ■ ' 1*8 »:00: ■ ' 123 5:00: * ' 102 l^uit 13. 19*; > windy 8:30:Claar a 86 10:001 • 118 11:00: ' 125 12:00: • 129 1:00 : ' 135 ' 2:00 : ■ . 130 5:00 : • 95 Aunuat 17. 19* } 8:00 CloudJ.allftnt 9:30 wind 10:*0 ■ ■ ■ J ll:»5 ■ a * J 12:50 ■ ■ • J 2:00 • ■ ■ J *:50 • • • : 67 96 112 129 125 129 _ip!_ 72 112 113 121 125 12* 130 131 127 135 136 123 123 120 75 107 120 121 126 127 123 133 128 131 131 129 115 95 9* 99 10* 112 112 116 118 109 118 118 11* 119 116 12* 123 121 125 121 81 90 97 110 11* 11* 116 113 88 77 100 102 103 10* 109 95 67 82 90 98 101 108 _25_ Taaparatura(rahranhalt) 7* 132 1*0 1*8 160 157 165 167 161 171 162 1*7 1*3 1*2 103 122 136 1*0 1*8 152 1*9 156 156 15* 152 1*6 129 95 98 107 116 12* 127 137 138 138 1*5 1*3 1*1 1*2 1*1 1*8 1** 138 1*0 137 81 102 116 1*0 138 1*3 1*1 122 96 83 108 116 123 125 125 97 67 95 105 12* 115 12* _21- 7* 1 7* 7* 71 131 129 129 103 139 : 138 1*5 138 1*8 106 1*6 1 115 155 • 152 157 119 155 1 158 158 : lie 160 : 160 165 121 162 162 166 121 160 : 160 107 122 161 : 160 16* : 125 161 1 161 1 165 128 1*7 1 1*3 1*5 120 1*2 1 1*2 in 121 1*2 1*2 118 103 1 101 100 92 120 120 122 105 139 13* 13* 115 138 138 1*0 117 1*5 1*5 1*5 119 1*8 1*8 150 121 1*7 1*7 1*8 118 153 1 153 153 120 155 155 155 122 152 152 153 125 151 151 152 126 1*6 1*6 1*6 12* 129 130 130 115 95 95 95 93 96 96 10* 90 105 105 93 112 112 111 96 121 123 123 101 125 123 123 10* 133 132 131 111 138 13* 13* 110 138 138 1*0 112 1*0 138 138 lie .-V 136 136 109 137 130 13* 105 1*2 137 137 111 1*0 133 135 116 1*5 1*1 139 117 1*2 139 139 11* 138 132 136 113 137 135 135 117 13* 133 . 133 116 81 81 79 79 101 99 99 85 11* 110 11* 93 132 131 . 131 103 138 . 138 : 138 101 1*0 . 135 1*1 102 1*0 137 : 1*0 113 120 . 121 : 122 103 96 96 96 . 91 82 83 : 83 : 77 110 : 110 : 110 93 113 : 113 : 113 88 119 : 119 : 119 93 12* : 121 : 121 9* 121 : 122 : 118 : 93 100 102 : 99 90 2Bi top &lu< llr.a 1 76 : ]** 1 155 167 182 177 180 180 179 181 180 170 166 : 155 1 108 is? : 155 158 169 166 175 167 166 165 153 135 90 : 102 : 111 1 116 1 131 : 135 : 1*2 1*6 150 155 : 152 1*7 151 150 152 153 1*2 1*6 1*0 78 111 127 1*6 15* 161 : 156 : 127 10* 85 125 121 130 1*1 130 93 81 Air taap. Faint Ralatlwa • :.»:« •urfaoa aumldltor taap. Faroai.t 67 77 73 1*1 7* 150 80 161 85 170 85 162 66 17* 51 69 162 87 179 91 178 96 17* 92 166 9* 16* 92 15* 72 106 79 129 6* 1** 68 152 6* 155 65 165 86 163 86 171 36 67 165 89 165 90 161 92 151 9* 137 88 90 62 M 76 62 101 86 107 90 123 86 116 96 122 66 135 *9 93 1*0 9* 150 93 1*6 91 139 92 1*2 92 139 52 96 1*5 99 1*0 100 1*0 99 136 96 135 *9 66 80 51 6* 89 66 97 71 102 »7 66 113 77 112 »1 76 120 61 100 7* 87 38 67 67 7* 72 71 76 1 52 72 76 76 : 76 ** 7* : 61 67 95 10* 122 117 12* _2S_ 67 95 105 lie : 115 121 i .W 66 9* 106 ue 117 121 W 67 72 6* 07 63 97 72 67 115 77 59 97 129 79 : 9* 126 78 5* 97 126 79 : 91 102 ■ 2 H U5176 F b - H > ■ aa 1 3 -< 1 O.M ■ o a i H O a a « QON 1 C range- yellow enamel 80 per cent Infra- red re- flect- ance over clear aealer 31 i r 5 : Blue- grey lacquer 5 percent infra-red reflect- ance over clear sealer m oanell as to Cllve drab 10 percent Infra-red reflect- ance over alualnized eealer ice of bott hi a ■ 1 Olive drab 50 percent lnf ro-red reflect- ance over alUDlnlsed sealer nslde surfi SB 1 OU"\ t J3 d ■ HZ 1 ** 1 SoE-iS It b 1 O O b (3 a a a a b a .0 ■* w v. a a ! •Ot>» I J eg?,fe * dSCal * a a a b a 1 (• a b <-< a an 1 •h v, *~ y «, c ohh E a 3 O at (0 1*1 A d . HZ 1 * £ d 1 H» 1 Orange- yello* enamel «0 per oent infra- red re- flect- ance clear sealer d X a Z 1 Blue- gray lacquer 5 neroent infra-red refleot- ance over clear sealer space *« gsi -S • 1 H I Z 1 Olive drab 10 percent infra-red refleot- ance over alumlnlzed sealer In the all z HZ 1 Olive drab 50 percent Infra-red reflect- ance over alunlnlzed sealer e Buependec to dos 1 B 1 b • 1 a 1 £Z ■ H 1 Olive drab 50 percent infra-red reflect- ance over clear eealer Thermocouri H H 1 Olive drab 10 peroent infra-red reflect- ance over clear eealer 0* 91 a 1 t9-| vihi. 1 a 1 b ! c -, e p.*» b a b en ! arid cv.'caoaad. bacoaca^c>rie 1 oxaaoo.4bv.aooa 1 £""♦»«)" U | a c a 1 a 1 , b b a b *j > k-i] 1 a b a a. b a 1 a »o-«br-<*.e_t ,E 3 u &V, v. a a id rlK ClCHd ia kti -. 1-. -h b a « 1 d z OVO 91 £ d 1 HZ 1 • ir« 01 III £Z 1 H 1 Cllve drab 10 percent infra-red reflect- ance over alumlnlted eealer face of to 01 E .1 a 1 e * i .0 *» -C 1 3 a c -o b a ia b 1 O C b 1 v >a^H*an ia — v. v. 3 a 1 c SS.5 £ s-3 : 5 i 1 ?: a 1 £Z 1 H > Olive drab 50 percent infra-red reflect- ance over clear eealer hermocounl( z ocu 1 e 1 Olive drab 10 peroent lnfro-red reflect- ance over clear sealer 1 z a 01 Oh 1 E .! a 1 e*i a a •3 a .1 b I a 1 v 1 jj"! ry -> S osoxco t-r- t-o>riM^»r.»ri^"-«>-i ^QOi>C»ilD«N P-P- o o\oo««) O O -1.. ;i 32225 3 Q\0\>cocOa> CACAQ C- 1/>C0 O\-A^O00 3 8 C* O SScOaS ■« oco o^^ H003t-t-4HO - O U*l iTl iTl iTl -» - sO H K\CO -H O f K-* ■«■«■* I^O O ■( O kA-O iT>-* CM^4 53 ^^.f-op-^p- t-p 1 1 o ; I bb ' wb'c c -55 a 0000000 00 3 000000000 oocoooo 00 f. O O O r O r~ o o o .bbbbbbb. 5 a c a >, Figbro 1. — The dummy wing partly assembled, shovdng some of the wiring for the thermocouples. IC •ir- •I 2C 3C 4C 5C GC IS 96 TOP VIEW vy r~\ " w 'HERMOCOUPLES END VIEW FIG. Z-FIRS1 DUMMY WING SHOWING DISTRIBUTION OF THE THERMOCOUPLES AND SYSTEM OF IDENTIFICATION NUMBERS Figure 3- — Th Q dummy wing in position on the Laboratory's south promenade. z u ^5173 P Figure ^. — Leading edge 6c, showing crack that opened after 2 days' exposure. This crack is at the beginning of the bend in the leading edge. r ~ SB 6C « * Figure 5.— Cracks that appeared after S days of exposure. Both section 6B and 6c were made with Butacite U-6U4; 6b was pressed, whereas 6c is a bag molded leading edge. zc ■ re 6. --Sections 2B and 2C after 1 „.„h.i «way from 2B aft'er" days'ex^ uresis J^ ^ ^ ll9i -Ided. using-Butacite UTCZli^'lT 011 ~ *' SPARS ~fx4 'SPRUCE ^THERMOCOUPLES I A i\b ♦^a-z-i-je-_-_- ic 4A R II -j ,| , __ *T\ ll >7\ W i *yt " " t " - hi 1< » i ' i, M / 'I 'tT^T^ = 9t = ='F = 5 ? S - jr^-_-_^_-^ _ « u ii U T| u ii U >iy >, 3C 4C RIB-CAPS -fxix/S" 5C R/BS-fx4 SPRUCE 108 16 TOP VIEW THERMOCOUPLES END VIEW FIG.l-SECOND DUMMY WING SHOWING DISTRIBUTION OP THERMOCOUPLES AND SYSTEM OF IDENTIFICATION NUMBERS z u 45175 f Figure S. — Second dummy wing in position on the Laboratory south promenade. UNIVERSITY OF FLORIDA 3 1262 08925 4360