Me\u00f0al loftaflsfr\u00e6\u00f0ileg breidd fundin \u00e1 mj\u00f3kkandi v\u00e6ng e\u00f0a deltav\u00e6ng<\/h2>\n
M\u00e6ldu r\u00f3tarbreidd og endabreidd v\u00e6ngsins. Teikna\u00f0u s\u00ed\u00f0an \u00feessar l\u00ednur \u00e1 teikninguna:<\/p>\n
- \n
- Vi\u00f0 r\u00f3tina \u00e1 v\u00e6ngnum dregur \u00fe\u00fa l\u00ednur sem eru sams\u00ed\u00f0a mi\u00f0l\u00ednu skrokksins fr\u00e1 frambr\u00fan og fram og fr\u00e1 afturbr\u00fan og aftur. B\u00e1\u00f0ar \u00feessar l\u00ednur eiga a\u00f0 vera jafn langar og endabreiddin.<\/li>\n
- Ger\u00f0u \u00fea\u00f0 sama vi\u00f0 endann, en haf\u00f0u lengd l\u00ednanna jafna r\u00f3tarbreiddinni.<\/li>\n
- Tengdu \u00feessar l\u00ednur me\u00f0 \u201eX\u201c yfir v\u00e6nginn. \u00dear sem \u00feessar l\u00ednur m\u00e6tast er me\u00f0al loftaflsfr\u00e6\u00f0ileg breidd (MAC) sta\u00f0sett.<\/li>\n
- Ef teikningin s\u00fdnir a\u00f0 jafnv\u00e6gispunkturinn skuli sta\u00f0settur \u00e1kve\u00f0na pr\u00f3sentu af MAC fr\u00e1 frambr\u00faninni, \u00fe\u00e1 \u00fearftu a\u00f0 m\u00e6la \u00feessa breidd og s\u00ed\u00f0an reikna pr\u00f3sentuna. Til d\u00e6mis ef MAC er 25 sm og teikningin s\u00fdnir a\u00f0 jafnv\u00e6gispunkturinn s\u00e9 25% fr\u00e1 frambr\u00fan, \u00fe\u00e1 er hann 6,25 fr\u00e1 frambr\u00faninni vi\u00f0 MAC.<\/li>\n<\/ul>\n
\u00deessi teikning \u00e6tti a\u00f0 \u00fatsk\u00fdra \u00fea\u00f0 sem veri\u00f0 er a\u00f0 tala um:<\/p>\n
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![\"mac\"](\"http:\/\/www.flugmodel.is\/wp-content\/uploads\/2013\/06\/mac-287x300.gif\")
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Athuga\u00f0u: L\u00ednurnar krossast \u00fear sem me\u00f0al loftaflsfr\u00e6\u00f0ileg breidd er. \u00de\u00e6r eru ekki a\u00f0 s\u00fdna sta\u00f0setningu jafnv\u00e6gispunktsins (nema hann eigi a\u00f0 vera \u00e1 50% MAC).<\/p>\n
Eftirfarandi form\u00fala gefur me\u00f0al loftaflsfr\u00e6\u00f0ilega breidd. H\u00fan gefur ekki sta\u00f0setningu hennar.<\/p>\n
rc = r\u00f3tarbreidd
\nt = mj\u00f3kkunarhlutfall = (endabreidd \/ r\u00f3tarbreidd)<\/p>\nMAC = rc x 2\/3 x (( 1 + t + t<\/b>2<\/b><\/sup> ) \u00f7 ( 1 + t ))<\/b><\/p>\n
Ef vi\u00f0 notum teikninguna h\u00e9r fyrir ofan og gefum okkur a\u00f0 r\u00f3tarbreiddin s\u00e9 28 sm og endabreiddin s\u00e9 15 sm, \u00fe\u00e1 er<\/p>\n
t = 15 \/ 28 = 0,5357<\/p>\n
N\u00fa getum vi\u00f0 sett t inn \u00ed form\u00faluna til a\u00f0 finna MAC. Athuga\u00f0u a\u00f0 v\u00e6nghaf og aftursveigja skipta ekki m\u00e1li. \u00dea\u00f0 er sama hvert v\u00e6nghafi\u00f0 er og hversu miki\u00f0 v\u00e6ngurinn er aftursveig\u00f0ur, me\u00f0al loftaflsfr\u00e6\u00f0ileg breidd ver\u00f0ur alltaf s\u00fa sama.<\/p>\n
MAC = 28 x 2\/3 x (( 1 + 0,5357 + 0,53572<\/sup> ) \/ ( 1 + 0,5357 ))
\nMAC = 56 \/ 3 x ( 1,8227 \/ 1,5357 )
\nMAC = 18,6666 x ( 1,8227 \/ 1,5357)
\nMAC = 18,6666 x 1,1869
\nMAC = 22,1547 sm<\/p>\nMe\u00f0al loftaflsfr\u00e6\u00f0ileg breidd fundin \u00e1 spor\u00f6skjuv\u00e6ng<\/h2>\n
MAC fyrir spor\u00f6skjuv\u00e6ng er 85% af r\u00f3tarbreiddinni og finnst alltaf 53% af hafi v\u00e6nghelmingsins fr\u00e1 r\u00f3tinni. Fl\u00f6tur v\u00e6nghelmingsins = 0,785 x v\u00e6nghaf x r\u00f3tarbreidd. \u00deeta virkar l\u00edka fyrir v\u00e6ngi sem eru ekki hreinar spor\u00f6skjur.<\/p>\n
<\/p>\n
![\"mac_ellipse\"](\"http:\/\/www.flugmodel.is\/wp-content\/uploads\/2013\/06\/mac_ellipse-300x109.gif\")
<\/a><\/p>\na = v\u00e6nghaf \/ 2
\nb = r\u00f3tarbreidd \/ 2<\/p>\n
\nH\u00f6fundarr\u00e9ttur \u00a9 2003 Paul K. Johnson
\n\u00de\u00fdtt me\u00f0 leyfi h\u00f6fundar \u2013 g<\/p>\n<\/p>\n","protected":false},"excerpt":{"rendered":"
M\u00f6rg kitt og teikningar s\u00fdna jafnv\u00e6gispunkt m\u00f3delsins (e. Centre of Gravity \u2013 CG) og segja jafnvel a\u00f0 hann skuli vera \u00e1 \u00e1kve\u00f0num sta\u00f0 \u00e1 me\u00f0al loftafsfr\u00e6\u00f0ilegri breidd (e. Mean Aerodynamic Chord \u2013 MAC) v\u00e6ngsins. \u00deessi sta\u00f0setning er venjulega gefin \u00ed … Halda \u00e1fram a\u00f0 lesa
![\"mac\"](\"http:\/\/www.flugmodel.is\/wp-content\/uploads\/2013\/06\/mac.gif\")
<\/a><\/p>\n