aircraft contruction and processes

8/11/2019 Aircraft Contruction and Processes

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PATTS REVIEW CENTERPATTS COLLEGE OF AERONAUTICS

Lombos Avenue, San Isidro, Paraaque City

AIRCRAFT CONSTRUCTION AND MANUFACTURING PROCESS

Aircraft Structural Componnt!

A" #oint!

All joints constructed using rivets, bolts, or special fasteners are lap joints. asteners cannotbe used on joints in !"ic" t"e materials to be joined do not overlap # for e$ample, butt, tee and edgejoints. A fayed edge %igure &'&( is a type of lap joint made !"en t!o metal surfaces are butted upagainst one anot"er in suc" a !ay as to overlap.

Internal aircraft parts are manufactured in four !ays) *illing, stamping, bending, ande$truding. +"e metal of a milled part is transformed from cast to !roug"t by first s"aping and t"eneit"er c"emically etc"ing or grinding it.

A stamped part is annealed, place in a forming press, and t"en re'"eat treated. ent parts aremade by s"eet metal mec"anics using t"e bend allowanceand layout procedures.

An e$trusion is an aircraft part, !"ic" is formed by forcing metal t"roug" a pres"aped die.+"e resulting !roug"t forms are used asspars, stringers, longerons, or channels.

igure &'- s"o!s a selection of e$truded s"apes used for t"e construction of many aircraftinternal parts. In order for metal to be e$truded, bent, or formed, it must firs be made malleable andductile by annealing. After t"e forming operation, t"e metal is re'"eat treated and age "ardened.

$" Win%!

&" Gnral

+"e aircraft !ing "as to be strong enoug" to !it"stand t"e positive forces of flig"t as !ell asnegative forces of landing. *etal !ings are of t!o types) Semi cantileverandfull cantilever, Semicantilever, or braced, !ings are used on lig"t aircraft. +"ey are e$ternally supported by struts orflying !ires, !"ic" connect t"e !ing spar to be fuselage.

A full cantilever !ing %igure &'( is usually made of stronger metal. It requires no e$ternalbracing or support. +"e s/in carries part of t"e !ingstress. Parts common to bot" !ing designs arespars, compression ribs, former ribs, stringers, stress plates, gussets, wing tips and wing skins%igure &'0(.

'" Spar!

+!o or more spars are used in t"e construction of a !ing. +"ey carry t"e main longitudinal #butt to tip # load of t"e !ing. ot" t"e spar and a compression rib connect t"e !ing to t"e fuselage.

(" Compr!!ion Ri)!

Compression ribs carry t"e main load in t"e direction of flig"t, from leading edge to trailingedge. 1n some aircraft, t"e compression rib is a structural piece of tubing separating t!o mainspars. +"e main function of t"e compression rib is to absorb t"e force applied to t"e spar !"en t"eaircraft is in flig"t.

*" Formr Ri)!

A former rib, !"ic" is made from lig"t metal, attac"es to t"e stringers and !ing s/ins to give

t"e !ing its aerodynamic s"ape. ormer ribs can be classified as nose ribs, trailing edge ribs, andmid rib running fore and aft bet!een t"e front and rear spar on t"e !ing. Formers are notconsidered primary structural members.

+" Strin%r!

Stringers are made of t"in s"eets of preformed e$truded or "and'formed aluminum alloy.+"en run front to bac/ along t"e fuselage and from !ing butt to !ing tip. 2iveting t"e !ing s/in tobot" stringer and t"e ribs gives t"e !ing additional strengt".

," Str!! Plat!

Stress plates are used on !ings to support t"e !eig"t of t"e fuel tan/. Some stress plates aremade of t"ic/ metal and some are of t"in metal corrugated for strengt". Stress plates are usually

&


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"eld in place by long ro!s of mac"ine scre!s, !it" self'loc/ing nuts, t"at t"read into speciallymounted c"annels. +"e stress'plate c"anneling is riveted to t"e spars and compression ribs.

-" Gu!!t!

3ussets, or gusset plates, are used on aircraft to join and reinforce intersecting structural members.

3ussets are used to transfer stresses from one member to anot"er at t"e point !"ere t"e membersjoin.

." Win% Tip!

+"e !ing tip, t"e outboard end of t"e !ing "as t!o purposes) +o aerodynamically smoot"out t"e !ing tip airflo! and to give t"e !ing a finis"ed loo/.

/" Win% S0in!

4ing s/ins cover t"e internal parts and provide for a smoot" airflo! over t"e surface of t"e !ing.1n full cantilever !ings, t"e s/ins carry stress. 5o!ever, all !ing s/ins are to be treated as primary

structures !"et"er t"ey are on braced or full cantilever surface.C" Fu!la% A!!m)li!

&" Gnral

+"ere are t!o types of metal aircraft fuselage) ull monocoque and semimonocoque. +"efull monocoque fuselage "as fe!er internal parts and more "ig"ly stressed s/in t"an t"esemimonocoque fuselage, !"ic" uses internal bracing to obtain its strengt".

+"e full monocoque fuselage is generally used on small aircraft, because t"e stressed s/ineliminates t"e need for stringers, former rings, and ot"er types of internal bracing, t"us lig"tening t"eaircraft structure.+"e semimonocoque fuselage derives its strengt" from t"e follo!ing internal parts) ul/"eads,longerons, /eel beams, drag struts, body supports, former rings, and stringers %igure &'6(

'" $ul01a2!

A bul/"ead is a structural partition, usually located in t"e fuselage, !"ic" normally runsperpendicular to t"e /eel beam or longerons. A fe! e$amples of bul/"ead locations are !"ere t"e!ing spars connect into t"e fuselage, !"ere t"e cabin pressuri7ation domes are secured to t"efuselage structure and at coc/pit passenger or cargo entry doors.

(" Lon%ron! 3 0l $am!

Longerons and /eel beams perform t"e same function in an aircraft fuselage. +"ey bot" carry t"e

bul/ of t"e load traveling fore and aft. +"e /eel beam and longerons, t"e strongest section of t"eairframe, tie its !eig"t to t"e ot"er aircraft part, suc" as po!erplants, fuel cells, and t"e landinggears.

*" Dra% Strut! 3 ot1r Fittin%!

8rag struts and body supports fittings are ot"er primary structural members. 8rag struts areused on large jet aircraft to tie t"e !ing to t"e fuselage center section. ody support fittings are usedto support t"e structures, !"ic" ma/e up bul/"ead or floor truss sections.

ormer rings and fuselage stringers are not primary structural members. ormer rings areused to give s"ape to t"e fuselage. uselage stringers running fore and aft are used to tie in t"ebul/"ead and former rings.

a" Empnna% Sction

+"e empennage is t"e tail section of an aircraft. It consists of a "ori7ontal stabili7er, elevator,vertical stabili7er and rudder %igure &'9(. +"e conventional empennage section contains t"e same/ind of parts used in t"e construction of a !ing. +"e internal parts of t"e stabili7ers and t"eir lig"tcontrols are made !it" spars. 2ibs, stringers and s/ins also, tail sections, li/e !ings can bee$ternally or internally braced.

&" 4ori5ontal Sta)ili5r an2 El6ator

+"e "ori7ontal stabili7er is connected to a primary control surface, i,e., t"e elevator. +"eelevator causes t"e nose of t"e aircraft to pitc" up and do!n. +oget"er, t"e "ori7ontal stabili7er and

elevator provide stability about t"e "ori7ontal a$is of t"e aircraft. 1n some aircraft, t"e "ori7ontal

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stabili7er is made movable by a scre!'jac/ assembly, !"ic" allo!s t"e pilot to trim t"e aircraftduring flig"t.

'" Vrtical Sta)ili5r an2 Ru22r

+"e vertical stabili7er is connected to t"e aft end of t"e fuselage and gives t"e aircraft

stability about t"e vertical a$is. Connected to t"e vertical stabili7er is t"e rudder, t"e purpose of!"ic" is to turn t"e aircraft about its vertical a$is.

E" Fli%1t Control

'" Ailron!

:levator and rudders are primary flig"t controls in t"e tail section. Ailerons are primaryflig"t controls connected to t"e !ings. Located on t"e outboard portion of t"e !ing, t"ey allo! t"eaircraft to turn bout t"e longitudinal a$is.

4"en t"e rig"t aileron is moved up!ard, t"e left one goes do!n, t"us causing t"e aircraft toroll to t"e rig"t. ecause t"is action creates a tremendous force, t"e ailerons must be constructed insuc" a !ay as to !it"stand it.

lig"t controls ot"er t"an t"e t"ree primary ones are needed on "ig"'performance aircraft.1n t"e !ings of a !ide'body jet, for e$ample, t"ere are a many as t"irteen flig"t controls, including"ig" and lo!'speed ailerons, flaps, and spoilers.

(" Flap! an2 Spoilr!

4ing flaps increase t"e lift for ta/e'off and landing. Inboard and outboard flaps on t"etrailing edge of t"e !ing, travel from full up, !"ic" is neutral aerodynamic flo! position, to fulldo!n, causing air to pile up and create lift. Leading edge flaps # ;rueger flaps and variable'camberflaps %igure &'


4/19

+"ere are t"ree steps involved in planning and e$ecuting a solid's"an/ rivet joint forstructural repair) Layout, installation, and inspection. igure 0'& is a c"art s"o!ing t"e rivet si7es,drill si7es, cleco colors, buc/ing bar !eig"ts, minimum edge distances and minimum rivet pitc"esfor layout and installation of t"e commonly used solid's"an/ rivets.

2I?:+8IA*:+:2

82ILLSI@:

CL:C1C1L12

C;IB3A2 4:I35+

:83:8IS+ABC:

2I?:+PI+C5

-&D6-&9

0EE-&&&

SIL?:2C1PP:2LAC;31L8

-'.E LS'0.E LS'0.6 LS6'9.6 LS

9-&0&E-9&9

F-6D&6-F&9

Fig. #-1 !ay out and *nstallation of solid-shank rivets

2ivet spacing is important !"en laying out rivets to obtain a joint, !"ic" is structurallysound and aest"etically balanced. +"e layout of rivets may be in ro!s abreast or transverse. 1ne oft"e advantages of placing rivets in transverse ro!s is t"at it reduces rivet failure along t"e metal>s

grain structure. 2ivets laid out in ro!s abreast "ave a greater tendency to fail along t"e grain.2ivet pitc" is t"e distance bet!een one rivet or ro! of rivets. *inimum rivet pitc" is 8, or

diameters, of t"e rivet being driven. %+"e diameter of a rivet is e$pressed as 8 and t"e lengt" asL(. Average rivet pitc" is 9 to D diameters. *a$imum rivet pitc" is -0 times t"e t"ic/ness of t"e tops"eet of metal. *inimum transverse pitc" is -.6 diameters of t"e rivet being driven.

:dge distance is t"e distance from t"e edge of t"e metal to t"e center of t"e first rivet or ro!of rivets. 1n aircraft, t"e minimum edge distance is -8 and t"e ma$imum is 08. If an edge distanceis larger t"an 08, t"e edges my curl up!ards and not lie flat and binding. 4"en aircraft rivets areinstalled using less t"an -8 edge distance, t"e bearing edge strengt" of t"e metal !ill !ea/en.

igure 0'- illustrates edge distance and rivet pitc". After t"e layout is computed, t"e firstinstallation operations are to center punc" t"e "oles, to select t"e correct drill, and to drill t"e "oles

to t"e proper si7e. All rivet "oles must be center punc"ed in order to prevent drill from !al/ing overt"e surface of t"e metal and defacing it. +"e indentation made by a center punc" must be "ardenoug" to catc" t"e point of t"e drill, yet lig"t enoug" to prevent denting t"e surrounding metal.Proper drill selection depends upon t"e si7e of t"e rivet being used. +"e "ole for a solid's"an/ rivetis drilled appro$imately E.EE- to E.EE0 of an inc" larger t"an t"e nominal rivet diameter.

A rivet t"at is driven into a properly prepared "ole needs to be si7ed according to diameterand lengt" so t"at a correct si7e buc/tail can be formed. igure 0' s"o!s t"e !idt" and "eig"t ofnormally driven buc/tail.

+"e use of t"in s/ins on any lig"t aircraft requires t"at t"e upset rivet "ead be 9 of an inc""ig" and &. inc"es !ide. +o determine t"e rivet lengt" for a particular job, t"e t"ic/ness of all t"emetal parts must be /no!n. All t"e individual t"ic/nesses of t"e metal are referred to as t"e grip

length. 5e grip lengt" plus &.68 is t"e proper lengt" of t"e rivet. %igure 0'0(

&" Ri6t Gun!

+"e "and tool used to drive a rivet is called a pneumatic rivet gun or rivet "ammer. 2ivetguns are normally po!ered by compressed air and are classifieds lig"t, medium, or "eavy "itting. Alig"t'"itting gun is used to install &- and &D inc" diameter rivets. *edium'"itting guns are used toinstall 6- and &9 inc" diameter rivets. 5eavy'"itting guns are used to install larger diameterrivets and some special fasteners.

+"ere are t!o types of gun sets, one for universal head rivetsand one for countersun/. +"euniversal gun set is si7ed to it t"e various s"apes of manufactured "eads on t"e rivet>s driven end.+"e opposite end of t"e universal gun set fits into t"e rivet gun barrel and is "eld in place by a

bee"ive retainer spring.+"e countersun/ gun set fits all si7es of flus" "ead rivets. +"e countersun/ rivet cannot use

t"e bee"ive retainer spring because it !ill not fit over t"e gun set retainer ring. +"e countersun/rivet set uses a specially designed retainer spring. igure 0'6 s"o!s bot" types of retainer springs.

'" $uc0in% $ar!

+"e tool used to from as upset "ead !"ile using a pneumatic rivet gun is buc/ing bar.uc/ing bars are made in various s"apes, si7es, and !eig"ts. +"e !eig"t of t"e buc/ing bar must beproportional to t"e si7e of t"e rivet.

+o obtain a proper upset "ead, a good tec"nique to use is s"o!n in igure 0'9. As t"e gun isfiring, press t"e buc/ing bar firmly against t"e forming rivet s"an/ and roll t"e bar slig"tly. +"is

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rolling action !ill aid in t"e formation or a barrel's"aped buc/tail. If t"e buc/ing bar is not "eldfirmly against t"e rivet s"an/, t"e metal !ill bend a!ay from t"e gun.

+"e smoot" face of t"e buc/ing bar must not be allo!ed to nic/ or scar. Bic/s or scars ont"e face of t"e buc/ing bar !ill mar/ t"e buc/tails and can lead to rivet failure. All scarred ormar/ed buc/tails must be drilled out and replaced !it" fres", unmar/ed rivets.

$" Ri6t Co2! an2 I2ntification

+"e manufacturing of all solid s"an/ rivets is governed by ederal Specification andStandards GG'A'0E. Solid's"an/ rivets are identified and catalogued by "ead s"ape, alloy content,s"an/ diameter, and s"an/ lengt". %igure 0'


6/19

protruding "ead rivets accounted for t"e development of a modified bra7ier "ead %069(, !"ic" casesless drag t"an larger protruding "ead rivets. +oday, bra7ier "ead rivet styles are li/ely to be foundonly on aircraft built before &F66. ecause t"e rivet sets used to drive rivets ot"er t"an universalsare difficult to obtain today, t"e older styles can be replaced by universal air rivets. AdvisoryCircular 0.&F'& e$plains t"e procedure

'" Countr!un0 Ri6t!

As aircraft speeds increased, t"e need for smoot" airfoils led to t"e development ofcountersun/ rivet. After e$perimenting !it" "ad angles of


7/19

metal ma/es t"is increase in strengt" possible. Alloyed aluminum rivets !"ic" are "eat treated andallo!ed to cool and age "arden as strong as and about one't"ird t"e !eig"t of steel. +"e alloys mostcommonly used to manufacture structural rivets are listed in igure 0'&-.

2ivet alloys &&EE and 6E695- are non'"eat treatable. Bon'"eat'treatable rivets are rarelyused on primary structures. +"e alloy &&EE contains an insignificant amount of copper %.E&J(. In

t"e AB or *S-E met"ods of cataloging, t"e &&EE alloy is designated by t"e letter A. +"e &&EE rivet"as no mar/ing on t"e *3 %manufactured( "ead. +"ese rivets are never used structurally, but areused in areas !"ere strengt" is not a major concern.

+"e only non'"eat'treated alloy is used for structural !or/ is 6E695-. It is used to s/inmagnesium'covered control surfaces because it is compatible !it" magnesium, its major alloyingingredient. *any lig"t aircraft control surfaces !ere at one time covered !it" magnesium alloy toreduce !eig"t. +"e only type of fastener t"at !ould not cause corrosion !as t"e magnesiumcompatible rivet 6E695-. +"e 6E695- rivet is identified by a raised cross on its *3 "ead and itis designated by t"e letter in t"e AB or *S-E catalog.

+"e alloy -&&


8/19

+oday, t"e re'"eating process is t"e same as t"e one originally used to "eat'treat t"e rivet, butimmediately after t"e rivet is quenc"ed, it is put into identified containers and stored in a free7er.+"e ne!er nic/name could be Kfree7er rivets.

Alloy suc" as -E-0 are follo!ed by a temper designation, made up of a letter and a number,!"ic" indicates t"e temper condition of t"e rivet. +0 means solution "eat'treated and age "ardened.

+ means solution "eat'treated, age "ardened, and t"en cold'!or/ed. A + rivet is one, !"ic" "asbeen driven. All driven rivets in t"e -MMM series alloys "ave a + or +& designation. 4"en a rivetli/e -E-0 "as t"e temper designation +&, as in -E-0+&, it means t"at t"e rivet is an icebo$ rivet.All driven icebo$ rivets "ave +& tag added to t"e alloy code.

or a long


9/19

Dri6n S1ar

Strn%t1 in :SIRi6t Diamtr

ALL1HS s - &D 6- &9 &0 6&9 D

-&&


10/19

Nominal Ri6t

Diamtr= In" &&D - &D 6- &9 &0 6&9 D

Rcommn22 4ol

Diamtr= In" E.E9< E.EF9 E.&-D6 E.&6F E.&F& E.-6< E.- E.D9

Corr!pon2in%Drill Si5 6& 0& E -& && P 4

Corr!pon2in% Sin%l

S1ar Ara= S>" In ?AS@ E.EE6 E.EE IN

E.E&9 E.EE&E< ''' ''' ''' ''' ''' ''' '''

E.E-E E.EE&0 E.EE&F- ''' ''' ''' ''' ''' '''

E.E-6 E.EE&9D E.EE-0E E.EE-& ''' ''' ''' ''' '''

E.E- E.EE-&0 E.EEE< E.EE0&& E.EE6EF ''' ''' ''' '''

E.E0E E.EE-9 E.EED0 E.EE6&0 E.EE99 E.EE


11/19

*3 "ead, to use a pin punc" !"ic" is t"e same si7e as t"e drill, to snap off t"e drilled *3 "eads,and to bac/ up eac" remaining stem by tapping out t"e s"an/ !it"out stretc"ing t"e metal.

A different procedure is follo!ed in removing t"e occasional rivet badly driven duringreassembly. Suc" rivets s"ould be removed t"e same si7e drill as t"e rivets being installed. 8rill t"edept" of t"e *3 "ead only, t"en lig"tly tap off t"e *3 "ead and gently /noc/ out t"e remaining

s"an/. igure 0'&F illustrates an assortment of faulty rivets, !"ic" must be removed and replaced.+"e most troublesome rivet fault is a clinc"ed rivet, !"ic" results from improper buc/ing action.+"e rivet forms to one side, !"ic" can lead to a corrosive condition at a later date. 2ivets t"at crac/do so because t"ey became too "ard !"ile t"e buc/tail !as forming. +"is is a result of "itting t"erivet too lig"tly or allo!ing an icebo$ rivet to recover its age "ardening by /eeping it out of t"efree7er too long before driving.I. Selecting 2ivet 8iameters and Lengt"s

In order to determine t"e correct rivet diameter, refer to t"e manufacturer>s manuals, comparet"e area to be riveted !it" anot"er aircraft of t"e same model and type, or multiply t"e t"ic/ness oft"e s/in, spar, or longeron by t"ree and t"e select a &- inc" larger rivet for t"e job. See appendi$

for an I* asic Language computer program, !"ic" can be used to find t"e rivet diameter.Correct rivet lengt" depends upon t"e t"ic/ness of t"e metal %grip lengt"( and t"e diameter oft"e rivet. +o find t"e lengt" of t"e rivet, add grip lengt" to t"e diameter of t"e rivet multiplied by&.6. +"en select t"e nearest larger si7e in &&9t"s. Cut t"e rivets to t"eir driving si7e !it" a pair ofrivet cutters.

Questions

1. Name four kinds of heat-treatable aluminum alloy rivets used manufacturing aircrafts.2. $hat are the 4leco 4olors that identify 52,15,&52, and 51(inch diameter rivets%

. $hat sie drill is used to pen holes for a 156 7 rivet%

#. $hat is the name of the )lcoa rivet alloy, which can replace icebo" rivets%

&. $hat aluminum alloy rivet is best suited for riveting magnesium skins%(. $hat marking does the rivets alloy 2118# have on the 9F: head%

. $hat marking does the rivets have to be reheated and5or refrigerated before driving%

. $hat is the name of the )lcoa alloy that was once considered an icebo" rivet%

/. 4onvert # 3S* to ;S*

10. $hat is the name )N letter code for the alloy 202#8#%

11. $hat joint strength is weakened by the use of machine-countersunk rivets%

12. 7escribe the N)4) method of countersinking rivets.

1. )ll thickness being e'ual, which rivet joint would have the highest shear strength< =niversal head

rivets, machine countersunk rivets%

1#. $hat is the ma"imum allowable edge distance for aircraft riveting%

1&. $hat is the formula for finding driven shear strength%

Answers:

&. -E-0+0, -&&


12/19

ecause cold !or/ing can eit"er !ea/en or strengt"en t"e metal, depending upon its previous degreeof "ardness, determining minimum bend radius is critical.

+"e minimum radius of t"e bend is determined by t"e "ardness and t"e t"ic/ness of t"e metal. igure9' is a minimum bend radius c"art. 4"en every "ard metals %suc" as


13/19

E.--Dor--


14/19

one degree of bend. If t"e si$'place decimal number is multiplied by any angle, it !ill produce t"ebend allo!ance for t"at angle.

or e$ample, to find t"e bend allo!ance for a FE bend !"en t"e radius is E.&-6 and t"et"ic/ness is E.E0E, read across t"e top line to E.&-6 t"en read do!n t"e t"ic/ness column until youget to E.E0E. +"e t"ree'place decimal, E--0, is t"e bend allo!ance for FE angle is E.EE-0F $ 06, or

E.&&-.

" Si%1t Lin

After all t"e measurements are laid out on t"e s"eet metal part, sig"t line must be located int"e bend allo!ance area. +"is is important for proper positioning of t"e bending bra/e in t"e bendallo!ance area prior to ma/ing t"e bend.

Location of t"e sig"t line affects t"e bend allo!ance around t"e bend radius bar because!"en metal is bent, t"e outside "eel stretc"es and t"e inside "eel compresses, causing t"e metal tostretc" at t"e point of t"e bend. +"e sig"t line placement for bends FE and greater is al!ays onebend radius out from t"e bend lineunder t"e nose of t"e bra/e. igure 9'6 s"o!s t"e location of t"esig"t line for bends FE and over.

4"en bends are smaller t"e FE, it is obvious t"at setting t"e sig"t line one bend radius outfrom t"e bend line !ill not be possible because t"e bend allo!ance area is too small. In t"is case, setnose of t"e bra/e in t"e middle of t"e bend allo!ance area.

$" St)ac0

Setbac/ is t"e calculation of t"e amount of metal to be subtracted from a leg in order to findt"e lengt" of its unbent portion, also referred to as t"e M distance %igure 9'9(. Simply stated,setbac/ is determined by subtracting t"e radius and t"e t"ic/ness from t"e lengt" of t"e finis"ed oft"e leg.

+"e formula for calculating setbac/ is)

S O %2+(?alues of ; are given in figure 9'


15/19

0.025 0.000736 0.001294 0.001835 0.002376 0.002917 0.003476 0.004017 0.004558 0.005098 0.005657

0.028 0.068

0.000759

0.119

0.001318

0.167

0.001859

0.216

0.002400

0.265

0.002941

0.315

0.003499

0.364

0.004040

0.412

0.004581

0.461

0.005122

0.511

0.005680

0.560

0.006221

0.609

0.005762

0.708

0.007853

0.804

0.007862

0.032 0.071

0.000787

0.121

0.001345

0.17

0.001886

0.218

0.002427

0.267

0.002968

0.317

0.003526

0.366

0.004007

0.415

0.004067

0.463

0.005149

0.514

0.005708

0.562

0.006249

0.611

0.006789

0.710

0.007889

0.807

0.008971

0.038 0.075

0.000837

0.126

0.001396

0.174

0.001937

0.223

0.002478

0.272

0.003019

0.322

0.003577

0.371

0.004118

0.419

0.004659

0.468

0.005200

0.518

0.005758

0.567

0.006299

0.616

0.005840

0.115

0.007940

0.612

0.009021

0.040 0.077

0.00853

0.127

0.00853

0.176

0.001952

0.224

0.002493

0.273

0.03034

0.323

0.003593

0.312

0.004132

0.421

0.004675

0.469

0.005215

0.520

0.005774

0.568

0.006315

0.617

0.006855

0.716

0.007955

0.813

0.009037

0.051 0.1340.001413

0.1830.002034

0.2320.002575

0.2800.003116

0.3310.003675

0.3790.004215

0.4280.004756

0.4770.005297

0.5270.005855

0.5760.006397

0.6240.006934

0.7230.008037

0.8210.009119

0.064 0.144

0.001595

0.192

0.002136

0.241

0.002676

0.290

0.003218

0.340

0.003776

0.369

0.004317

0.437

0.004058

0.486

0.005399

0.536

0.005957

0.585

0.006498

0.534

0.007039

0.732

0.008138

0.830

0.009220

0.072 0.198

0.002202

0.247

0.002143

0.296

0.003384

0.346

0.003842

0.385

0.004203

0.443

0.004924

0.492

0.005465

0.542

0.006023

0.591

0.006564

0.639

0.007105

0.738

0.00825

0.836

0.009287

0.078 0.202

0.002247

0.251

0.002787

0.300

0.003327

0.390

0.003885

0.399

0.004426

0.447

0.004963

0.496

0.005512

0.546

0.006070

0.595

0.006611

0.644

0.007152

0.742

0.008243

0.640

0.009333

0.081 0.204

0.00227

0.253

0.002811

0.302

0.003351

0.352

0.003909

0.401

0.004449

0.449

0.004969

0.498

0.005535

0.546

0.006094

0.598

0.006635

0.646

0.007176

0.744

0.008266

0.642

0.009357

0.091 0.212

0.00235

0.260

0.002891

0.309

0.003432

0.359

0.003990

0.408

0.004531

0.456

0.005072

0.505

0.005613

0.555

0.006172

0.604

0.006113

0.653

0.007254

0.752

0.008853

0.849

0.009435

0.094 0.214

0.002374

0.262

0.002914

0.311

0.003455

0.361

0.004074

0.410

0.004555

0.459

0.005096

0.507

0.005637

0.588

0.006195

0.606

0.006736

0.655

0.007277

0.754

0.008376

0.851

0.009458

0.102 0.266

0.002977

0.317

0.003518

0.367

0.004076

0.416

0.004617

0.464

0.005158

0.513

0.005699

0.563

0.006257

0.612

0.006798

0.661

0.007339

0.700

0.008439

0.957

0.009521

0.109 0.213

0.003031

0.321

0.003572

0.372

0.004131

0.420

0.004612

0.469

0.005213

0.518

0.005754

0.568

0.006312

0.617

0.006653

0.665

0.008394

0.764

0.008493

0.862

0.009575

0.125 0.284

0.003156

0.333

0.003697

0.383

0.004256

0.432

0.004797

0.48

0.005338

0.529

0.005678

0.579

0.006437

0.628

0.006978

0.677

0.007519

0.776

0.008618

0.673

0.009700

0.156 0.355

0.003839

0.405

0.004497

0.453

0.005038

0.502

0.0005579

0.551

0.00612

0.601

0.006679

0.650

0.007220

0.698

0.007761

0.797

0.008860

0.895

0.009942

0.188 0.417

0.004747

0.476

0.003288

0.525

0.005829

0.573

0.006370

0.624

0.006928

0.672

0.007469

0.721

0.008010

0.820

0.009109

0.917

0.010191

0.250 0.568

0.006313

0.617

0.06853

0.667

0.007412

0.716

0.007053

0.764

0.008484

0.853

0.009593

0.961

0.010675

Fig (-# >end allowance chart

+"e ;'factor values are arrived at by dividing any angle by t!o and finding !"at t"e tangentequivalent is. or e$ample, a 06 angle divided by t!o is --.6. 1n t"e tangent table, igure 9'


16/19

6 E.E099 96 E.9


17/19

E.- E.EE0F E.EE0F -D9.6 &.EEEE DF.D

E. E.EE6-0 E.EE6-0 &F&.E &.EEEE DF.

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