Elastomeric riblets

Abstract

An array of aerodynamic riblets incorporates a high elongation elastomeric layer having spaced tips and optionally a protective cladding. The elastomeric layer may be adhered to an aerodynamic surface directly or as an appliqué in combination with one or more of an adhesive layer, one or more supporting polymer layers and a metal foil layer.

1 . A method for fabricating an array of riblets comprising:
 forming a master tool shaped corresponding to a desired riblet array:   forming at least one complementary tool from the master tool;   depositing a high elongation elastomeric layer having tips and a surface layer in the complimentary tool;   depositing an adhesive layer to form an appliqué;   removing the high elongation elastomeric appliqué from the complementary tool; and,   adhering the high elongation elastomeric appliqué to an aerodynamic surface.   
     
     
         2 . The method of  claim 1  further comprising:
 applying a release agent to the complementary tool for separation of the high elongation elastomeric layer from the tool. 
 
     
     
         3 . The method of  claim 1  further comprising depositing at least one polymer layer intermediate the adhesive layer and the elastomeric layer. 
     
     
         4 . The method of  claim 1  further comprising depositing a cladding over the high elongation elastomeric layer. 
     
     
         5 . A method creating an array of riblets in an appliqué comprising:
 forming a master tool shaped corresponding to a desired riblet array: 
 forming a web tool from the master tool; 
 depositing a high elongation elastomeric layer to form tips and a surface layer in the web tool; 
 depositing an adhesive layer to form an appliqué; 
 adhering the high elongation elastomeric appliqué to an aerodynamic surface; and, 
 removing the web tool from the high elongation elastomeric appliqué. 
 
     
     
         6 . The method of  claim 5  further comprising depositing a cladding on the web tool prior to depositing the high elongation elastomeric layer. 
     
     
         7 . The method of  claim 5  further comprising a step intermediate to depositing the elastomeric layer and depositing the adhesive layer of laminating a metallic layer and polymer support layer to the elastomeric layer. 
     
     
         8 . The method of  claim 5  wherein the step of depositing an adhesive layer comprises:
 creating a pre-made appliqué without a topcoat (TLA); 
 laminating the TLA onto the high elongation elastomeric layer deposited in the web tool. 
 
     
     
         9 . A method of enhancing the durability of a riblet comprising:
 forming an array of a plurality of riblets including a first layer composed of high elongation elastomeric riblets having tips, a surface layer, and a second layer for adherence to a surface; and   adhering the array of riblets to an aerodynamic surface.   
     
     
         10 . The method of  claim 1  further comprising diamond machining of a copper form as the master tool. 
     
     
         11 . The method of  claim 5  wherein the step of forming a master tool comprises diamond machining of a copper form as the master tool. 
     
     
         12 . The method of  claim 11  further comprising:
 curing an polymer film on the copper form; 
 stripping polymer film; and, 
 applying the film to a roller. 
 
     
     
         13 . The method of  claim 12  wherein the step of forming a web tool comprises impressing the web tool on the roller. 
     
     
         14 . The method of  claim 5  wherein the step of depositing an elastomeric layer comprises casting the elastomeric layer from a liquid state using a roll coating method selected from the set of gravure, 3- or 4-reverse roll, knife over roll, slot die, spray or immersion. 
     
     
         16 . The method of  claim 5  further comprising adding a removable adhesive liner over the riblets for handling. 
     
     
         17 . The method of  claim 9  wherein the step of forming an array of a plurality of riblets comprises:
 diamond machining of a copper form as a master tool shaped corresponding to a desired riblet array: 
 curing an polymer film on the copper form; 
 stripping polymer film; and, 
 applying the film to a roller; 
 depositing a high elongation elastomeric layer to form tips and a surface layer in the web tool; and, 
 depositing an adhesive layer to form an appliqué. 
 
     
     
         18 . The method of  claim 17  further comprising depositing a cladding on the web tool prior to depositing the high elongation elastomeric layer 
     
     
         19 . The method of  claim 17  further comprising adding a removable adhesive liner over the riblets for handling. 
     
     
         20 . The method of  claim 19  further comprising removing the adhesive liner after adhering the array of riblets to the aerodynamic surface.