Aeronautics and astronautics – Aircraft sustentation – Sustaining airfoils
Patent
1982-09-29
1984-02-07
Blix, Trygve M.
Aeronautics and astronautics
Aircraft sustentation
Sustaining airfoils
B64C 348
Patent
active
044298447
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to variable camber aircraft wing tips useful in mission adaptive wings which are being designed with the capability to reconfigure airfoil geometry in flight and to improve aerodynamic performance throughout that envelope.
BACKGROUND ART
The aerodynamic design of modern aircraft is a compromise between many conflicting requirements, thus limiting near optimum aerodynamic performance to a small portion of the aircraft flight envelopes. In the use of mission adaptive wing technology, sizable improvements in payload range, maneuverability, and ride quality are made possible.
One technical approach to the mission adaptive wing involves the use of variable camber leading and trailing edge flaps having smooth upper surface flexible panels. The panels are adapted to change shape when the flaps are deflected during flight. It is of particular interest to adapt the mission adaptive wing to a variety of wing planform geometries.
Specifically, in the area of wing tips, compound curvature prevents the use of a prior art basic variable camber actuation system, and a more sophisticated method of closing out a wing leading edge flap is required. Whereas a variable camber wing tip is not specifically required for a fixed wing application, it is a definite requirement for a variable sweep wing, and is aerodynamically desirable for fixed wings using variable camber leading edges.
The only known prior attempt to make a variable camber wing tip was in the form of a solid plug deflectable with respect to the surrounding wing structure. This type of wing tip presented large discontinuities between the tip and adjacent wing structure in all deflected positions. The large discontinuities resulted in high drag to the extent that the wing tip design was considered to be unsatisfactory.
A search of the patent literature discloses a number of variable camber wing structures which are not directly pertinent. French Pat. No. 568,605 illustrates a variable camber wing that does not have a compound curvature in the deflected position. Similarly, U.S. Pat. No. 1,747,637 teaches a variable camber wing that is increased in thickness when the camber is increased but it also does not teach a compound curvature.
The following patents disclose various forms of wing structures:
DISCLOSURE OF THE INVENTION
The invention is a variable camber wing tip and such wing tip in combination with an aircraft wing having variable camber leading and trailing flaps. The wing tip has normal or nominal camber in an upper position and is adapted to have an increased camber curvature in a deflected down position. The wing tip has a fore and aft extending end secured along a complementary outer end of a variable camber leading edge of the wing and a trailing edge of the wing tip extends along a fixed outboard forwardly facing edge of the wing. The wing tip in the down position has a compound curvature, that is, curving forwardly downwardly and outboardly downwardly, and being shortened in the fore and aft direction and generally thickened.
There are means within the wing tip adapted to be actuated by means within the wing leading edge portion to vary the camber from the upper position to the down deflected position and return.
The wing tip is generally triangular in plan and has a leading edge which is adapted to be generally at an acute angle with the leading edge of the aircraft wing. The means, within the wing tip when actuated to vary the camber in the down position, increases the depth of the wing tip and shortens it in the fore and aft direction and creates the compound curvature.
The actuatable means in the wing tip include multiple, generally parallel scissor plates, extending in an inboard-outboard direction and spaced in the fore and aft direction. The scissor plates are upper and lower plates with respect to the upper and lower surfaces of the wing tip. The upper plates are pivotally secured inboard to the wing variable camber leading edge so as to secure an upper portion of the wing tip to the wing. The low
REFERENCES:
patent: 1203558 (1916-10-01), Gallaudet
patent: 1567531 (1925-12-01), Magni
patent: 1731666 (1929-10-01), Jackson
patent: 1747637 (1930-02-01), Larsen
patent: 2022806 (1935-12-01), Grant
patent: 2820601 (1958-01-01), Crawford
patent: 3152775 (1964-10-01), Boyd
patent: 4351502 (1982-09-01), Statkus
Brown Stephen T.
Statkus Frank D.
Blix Trygve M.
Corl Rodney
Heberer Eugene O.
The Boeing Company
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