POSITIVE TAIL LOADS FOR MINIMUM INDUCED DRAG OF SUBSONIC AIRCRAFT

It is proved that, regardless of the relative size of the tail, the downwash produced by a tail download increases the induced drag of the wing so as to cancel the additional "tail thrust" , and keep the mutually induced drag of a wing-tail combination the same as that induced upon the tail alone when it is in the wing's Trefftz-plane. At any finite tail length the bound circulation vortex of the wing produces a downwash that increases the induced drag of a tail upload. However, the circulation vortex system of the tail upload produces an upwash on the wing that results in a "wing thrust" components that cancels the increased drag on the tail so that the total induced drag is a minimum with a positive tail load. In order to facilitate the calculation of the mutually induced drag of typical wing-tail combinations, an explicit relation is derived for the limiting case of a small-span tail at any distance above or below a large-span wing.

  • Availability:
  • Corporate Authors:

    American Institute of Aeronautics and Astronautics

    1290 Avenue of the Americas
    New York, NY  United States  10019
  • Authors:
    • Laitone, E V
  • Publication Date: 1978-12

Media Info

  • Features: References;
  • Pagination: p. 837-842
  • Serial:
    • Journal of Aircraft
    • Volume: 15
    • Issue Number: 12
    • Publisher: American Institute of Aeronautics and Astronautics
    • ISSN: 0021-8669

Subject/Index Terms

Filing Info

  • Accession Number: 00196078
  • Record Type: Publication
  • Source Agency: Engineering Index
  • Files: TRIS
  • Created Date: Aug 15 1979 12:00AM