11.4 Connections 363flyingcontrolsurfaces.Thus,forexample,theaileronsandrudderoftheBritishAerospaceJaguarare
fabricated from aluminium honeycomb, while fiberglass- and aluminium-faced honeycomb are used
extensivelyinthewingsandtailsurfacesoftheBoeing747.Someproblems,mainlydisbondingand
internalcorrosion,havebeenencounteredinservice.
Thegeneralprinciplesrelatingtowingconstructionareapplicabletofuselages,withtheexception
that integral construction is not used in fuselages for obvious reasons. Figures 11.5, 11.6, and 11.7
showthatthesamebasicmethodofconstructionisemployedinaircrafthavingwidelydifferingroles.
Generally,thefuselageframesthatsupportlarge,concentratedfloorloadsorloadsfromwingortailplane
attachmentpointsareheavierthanlightlyloadedframesandrequirestiffening,withadditionalprovision
fortransmittingtheconcentratedloadintotheframeandhencetheskin.
Withtheframesinpositioninthefuselagejig,stringers,passingthroughcutouts,arerivetedtothe
frame flanges. Before the skin is riveted to the frames and stringers, other subsidiary frames such as
doorandwindowframesarerivetedorboltedinposition.Theareasofthefuselageintheregionsof
thesecutoutsarereinforcedbyadditionalstringers,portionsofframe,andincreasedskinthickness,to
reacttothehighshearflowsanddirectstressesdeveloped.
Oncompletion,thevarioussubassembliesarebroughttogetherforfinalassembly.Fuselagesections
areusuallyboltedtogetherthroughflangesaroundtheirperipheries,whilewingsandthetailplaneare
attachedtopickuppointsontherelevantfuselageframes.Wingsparsonlowwingcivilaircraftusually
pass completely through the fuselage, simplifying wing design and the method of attachment. On
smaller, military aircraft, engine installations frequently prevent this so that wing spars are attached
directlytoandterminateatthefuselageframe.Clearly,atthesepositionsframe/stringer/skinstructures
requirereinforcement.
11.4 Connections...........................................................................................
The fabrication of aircraft components, generally, involves the joining of one part of the component
to another. For example, fuselage skins are connected to stringers and frames, whereas wing skins
areconnectedtostringersandwingribsunless,asinsomemilitaryaircraftwithhighwingloadings,
the stringers are machined integrally with the wing skin (see Section 11.3). With the advent of all-
metal—aluminumalloy—construction,rivetedjointsbecamethemainformofconnectionwithsome
welding,althoughaluminumalloysaredifficulttoweld,and,inthemodernera,somegluedjointswhich
useepoxyresin.Inthissection,weshallconcentrateonthestillpredominantmethodofconnection:
riveting.
Ingeneral,rivetedjointsarestressedincomplexways,andanaccurateanalysisisveryoftendifficult
toachievebecauseofthediscontinuitiesintheregionofthejoint.Fairlycrudeassumptionsastojoint
behavioraremade,but,whencombinedwithexperience,safedesignsareproduced.
11.4.1 Simple Lap Joint
Figure11.11showstwoplatesofthicknesstconnectedtogetherbyasinglelineofrivets;thistypeof
jointistermedalapjointandisoneofthesimplestusedinconstruction.