Winglet system

Patent metadata

Field	Value
Publication number	US-9346537-B2
Application number	US-201514942988-A
Country	US
Kind code	B2
Filing date	Nov 16, 2015
Priority date	Mar 30, 2012
Publication date	May 24, 2016
Grant date	May 24, 2016

Abstract

A winglet system for an aircraft wing may include an upper winglet and a lower winglet mounted to a wing tip. The upper winglet root chord and the lower winglet root chord may each have a length of no greater than 100 percent of the wing tip chord. The lower winglet may have a static position when the wing is subject to an on-ground static loading. The lower winglet may be configured such that upward deflection of the wing under an approximate 1-g flight loading causes the lower winglet to move upwardly and outwardly from the static position to an in-flight position resulting in an effective span increase of the wing under the approximate 1-g flight loading relative to the span of the wing under the on-ground static loading.

First claim

What is claimed is:

1. A winglet system, comprising:
an upper winglet and a lower winglet each having a root chord and being mounted to a wing tip of a wing, the wing tip having a wing tip chord;
the upper winglet root chord and the lower winglet root chord each having a length of no greater than 100 percent of the wing tip chord;
the lower winglet having a static position when the wing is subject to an on-ground static loading; and
the lower winglet being configured such that upward deflection of the wing under an approximate 1-g flight loading causes the lower winglet to move upwardly and outwardly from the static position to an in-flight position resulting in an effective span increase of the wing under the approximate 1-g flight loading relative to the span of the wing under the on-ground static loading.

2. The winglet system of claim 1 , wherein:
the upper winglet root chord and the lower winglet root chord each have a length of at least approximately 50 percent of the wing tip chord.

3. The winglet system of claim 1 , wherein:
the upper winglet root chord and the lower winglet root chord each have a length of from approximately 60 to 100 percent of a length of the wing tip chord.

4. The winglet system of claim 1 , wherein:
at least one of the upper winglet and lower winglet has a leading edge root glove mounted at a juncture of the wing tip with the respective upper winglet and lower winglet.

5. The winglet system of claim 1 wherein:
the lower winglet is oriented at an anhedral angle of no less than approximately 15 degrees during the upward deflection of the wing under the approximate 1-g flight loading.

6. The winglet system of claim 1 wherein:
the upper winglet is oriented at a dihedral angle of at least approximately 60 degrees during upward deflection of the wing under the approximate 1-g flight loading.

7. The winglet system of claim 1 , wherein:
an upper winglet tip and a lower winglet tip terminate at approximately the same lateral location when the wing is under the on-ground static loading.

8. The winglet system of claim 1 , wherein:
the upper winglet and the lower winglet each have a taper ratio of tip chord to root chord in a range of from approximately 0.15 to 0.50.

9. The winglet system of claim 1 , wherein:
the upper winglet and the lower winglet have a leading edge sweep angle of between approximately 20 and 70 degrees.

10. The winglet system of claim 1 wherein:
the lower winglet has a center of pressure;
the wing having a wing torsional axis; and
the center of pressure of the lower winglet being located aft of the wing torsional axis.

11. An aircraft, comprising:
a pair of wings each having a wing tip including a wing tip chord;
an upper winglet and a lower winglet mounted to each one of the wing tips, the upper winglet and the lower winglet each having a root chord;
the upper winglet root chord and the lower winglet root chord each having a length of no greater than 100 percent of the wing tip chord;
the lower winglet having a static position when the wing is subject to an on-ground static loading; and
the lower winglet being sized and oriented such that upward deflection of the wings under an approximate 1-g flight loading causes the lower winglet to move upwardly and outwardly from the static position to an in-flight position resulting in an effective span increase of the wing under the approximate 1-g flight loading relative to the span of the wing under an on-ground static loading.

12. A method of enhancing performance of an aircraft, comprising the steps of:
providing an upper winglet and a lower winglet on a wing tip of a wing, the wing tip having a wing tip chord, the lower winglet having a static position when the wing is subject to an on-ground static loading, the upper winglet and the lower winglet each having a root chord having a length of no greater than 100 percent of the wing tip chord;
upwardly deflecting the wing under an approximate 1-g flight loading;
moving the lower winglet upwardly and outwardly from the static position to an in-flight position during upward deflection of the wing; and
causing an effective span increase of the wing under the approximate 1-g flight loading relative to the span of the wing under the on-ground static loading in response to moving the lower winglet upwardly and outwardly from the static position to the in-flight position.

13. The method of claim 12 , wherein:
the upper winglet root chord and the lower winglet root chord each have a length of at least approximately 50 percent of the wing tip chord.

14. The method of claim 12 , wherein:
the upper winglet root chord and the lower winglet root chord each have a length of from approximately 60 to 100 percent of a length of the wing tip chord.

15. The method of claim 12 , further comprising the step of:
minimizing parasitic drag of the aircraft by using a leading edge root glove on at least one of the upper winglet and the lower winglet.

16. The method of claim 12 , further comprising the step of:
orienting the lower winglet at an anhedral angle of no less than approximately 15 degrees during the upward deflection of the wing under the approximate 1-g flight loading.

17. The method of claim 12 , further comprising the step of:
orienting the upper winglet at a dihedral angle of at least approximately 60 degrees during the upward deflection of the wing under the approximate 1-g flight loading.

18. The method of claim 12 , wherein:
an upper winglet tip and a lower winglet tip terminate at approximately the same lateral location when the wing is under the on-ground static loading.

19. The method of claim 12 , further comprising the steps of:
locating the lower winglet such that a center of pressure is aft of a wing torsional axis;
increasing lift of the lower winglet during a gust load; and
exerting a nose-down moment on a wing tip in response to an increase in the lift of the lower winglet.

20. The method of claim 12 , further comprising the step of:
dividing a wing tip aerodynamic load between the upper winglet and the lower winglet.

Assignees

• Boeing Co

Inventors

• Roman Dino L
• Vassberg John C
• Friedman Douglas M
• Malachowski Adam P
• Vegter Christopher A

Classifications

• B64C5/10 Primary

  adjustable · CPC title

• B64C3/58

  provided with fences or spoilers (adjustable for control purposes B64C9/00) · CPC title

• B64C5/08 Primary

  mounted on, or supported by, wings · CPC title

• B64C23/069 Primary

  using one or more wing tip airfoil devices, e.g. winglets, splines, wing tip fences or raked wingtips · CPC title

• B64C23/065 Primary

  at the wing tips · CPC title