I read somewhere before that the effect of the dihedral wing is similar to the swept wing so dihedral wing increase wingtip loading and increase induced drag
Can anyone tell me how physically this is possible ?
Aviation Stack Exchange is a question and answer site for aircraft pilots, mechanics, and enthusiasts. It only takes a minute to sign up.Sign up to join this community
There is some academic writing about this phenomenon. The most articulate explanation I have read comes from a paper Induced Drag and Winglets by R. Eppler, Universität Stuttgart, which was presented at the XXIV OSTIV Congress in 1995.
Winglets and other forms of wing tips with dihedral increase not only the effective span, but also the wetted area of the wing. Although the induced drag is considered to be completely independent of the viscous drag, for a correct comparison of different wings it is necessary to add to the induced drag that part of the viscous drag that is due to the difference in wetted area.
It's an interesting read and the section provides illustrative formulas (16) through (21) for those mathematically inclined.
A grainier "old school" PDF is available at this link from Simon Fraser University.
Eppler has written several books and scholarly articles on airfoil design.