Morphing aircraft skin with embedded viscous peeling network

Patent metadata

Field	Value
Publication number	US-11834170-B2
Application number	US-202017422539-A
Country	US
Kind code	B2
Filing date	Jan 15, 2020
Priority date	Jan 15, 2019
Publication date	Dec 5, 2023
Grant date	Dec 5, 2023

Abstract

An airfoil surface skin, comprising a network of a solid material, embedded in a base of deformable solid material. Fluid pressure applied to the interface between the network and the surrounding embedding material, opens an internal network of channels by viscous peeling of the surrounding solid from the network. The network is offset from the centerline the surround material, such that pressure driven viscous flow through the narrow channels generates two types of deformation of the skin—an in-plane elongation and a curvature of the skin plane itself. The shape of the internal solid core element and its material, and the material of the encompassing solid are chosen to achieve a desired integral structural rigidity. The injected fluid pressure determines the extent of extension and bending. Use of this skin enables shape amending airfoils having reduced drag compared with similar airfoils having conventional flap mechanisms.

First claim

We claim:

1. An airfoil comprising:
a surface layer skin;
a base layer of a solid material having a predetermined flexibility, wherein the base layer is embedded within the surface layer skin;
a network comprising a solid core material having a higher rigidity than that of the base layer, the network being embedded in the base layer with at least part of the network at a depth offset from the center of the thickness of the base layer; and
at least one fluid connector disposed such that pressurized fluid from the connector is applied to at least one point at an interface between the network and the surrounding base layer, causing peeling of the base layer from the network;
wherein the surface shape of an airfoil comprising the surface layer skin is changed on adjustment of the pressure of the fluid applied to the surface layer skin.

2. The airfoil according to claim 1 , wherein the change of shape is generated by the anisotropic change in the flexibility of the surface layer skin by propagation of peeling along the network.

3. The airfoil according to claim 1 , wherein the change of shape is further determined by at least one of geometry of the network, base layer geometry, the flexibility of the base layer; and positioning of the network within the base layer.

4. The airfoil according to claim 2 , wherein the geometry of the network is configured to generate the anisotropic change in the flexibility of the surface layer skin.

5. The airfoil according to claim 1 , wherein the network has a serpentine form.

6. The airfoil according to claim 1 , wherein the network has first segments having essentially parallel straight form, and shorter second segments connecting adjacent first segments.

7. The airfoil according to claim 6 , wherein the first segments are aligned in directions generally parallel to the axes around which the airfoil surface layer is intended to bend, or wherein the shorter second segments connect the first segments at alternating ends of the first segments, such that the network has an essentially serpentine form.

8. The airfoil according to claim 1 , wherein the interface between the network and the surrounding base layer comprises a common surface shared by the base layer and the network.

9. The airfoil according to claim 1 , wherein the peeling of the base layer from the network creates an internal channel between the base layer and the network.

10. The airfoil according to claim 9 , wherein the channel is created by the application of the pressurized fluid.

11. The airfoil according to claim 1 , wherein a separation between the base layer and network is created when the pressurized fluid is applied.

12. The airfoil according to claim 1 , wherein the change of shape of the airfoil surface layer is adapted to change at least one of the airfoil camber, the airfoil chord, the airfoil thickness, or the spanwise wash of a lifting surface.

13. The airfoil according to claim 1 , wherein the change of shape of the airfoil surface layer provides the airfoil with a reduced drag coefficient compared with a similar airfoil having a conventional shape changing mechanism.

14. The airfoil according to claim 1 , wherein a time dependent adjustment of the pressure of the fluid applied to the surface layer skin is operative to generate time dependent deformations of the airfoil surface.

15. The airfoil according to claim 1 , wherein the at least one fluid connector comprises more than one fluid connector supplying pressurized fluid to more than one point along the network interface with the base layer.

16. The airfoil according to claim 1 , wherein the network comprises a number of separately actuated segments.

17. The airfoil according claim 1 , wherein the network is embedded in the base layer having a state of compression, such that when freed from the base layer by peeling of the base layer from the network, the network undergoes an expansion.

18. The airfoil according to claim 17 , wherein the expansion of the network generates an extension of the airfoil.

19. A method of providing reduced drag to an airfoil, by constructing an airfoil according to claim 1 , the airfoil having reduced drag compared with an equivalent airfoil whose shape is changed by use of mechanical elements to move sections of the airfoil.

20. The method of claim 19 , wherein the airfoil further has at least one of better control authority and higher efficiency throughout a flight envelope of an aircraft incorporating the airfoil compared with an equivalent airfoil whose shape is changed by use of mechanical elements to move sections of the airfoil.

Assignees

• Technion Res & Dev Foundation

Inventors

• Elbaz Shai
• Salem Lior
• Gamus Benny
• Or Yizhar
• Gat Amir
• Peretz Ofek

Classifications

• B64C3/48 Primary

  by relatively-movable parts of wing structures · CPC title

• B64C3/26

  Construction, shape, or attachment of separate skins, e.g. panels · CPC title

• B64C2003/445

  by changing shape according to the speed, e.g. by morphing · CPC title

• B64C3/46 Primary

  by inflatable elements · CPC title

• Y02T50/10

  Drag reduction · CPC title