Aircraft hydraulic system

Abstract

An aircraft hydraulic system utilizes a hydraulic fluid that includes a heat transfer fluid and a friction modifier additive.

What is claimed is: 
     
         1 . An aircraft hydraulic system comprising:
 a hydraulic fluid including a heat transfer fluid and a friction modifier.   
     
     
         2 . The aircraft hydraulic system set forth in  claim 1 , wherein the heat transfer fluid is hydrocarbon-based. 
     
     
         3 . The aircraft hydraulic system set forth in  claim 2 , wherein the aircraft hydraulic system is a friction plate brake system. 
     
     
         4 . The aircraft hydraulic system set forth in  claim 2 , wherein the aircraft hydraulic system is a clutch system. 
     
     
         5 . The aircraft hydraulic system set forth in  claim 3  further comprising:
 a friction plate exposed to the hydraulic fluid. 
 
     
     
         6 . The aircraft hydraulic system set forth in  claim 5 , wherein the friction modifier includes a long chain molecule having a polar end associated with the friction plate and a non-polar end associated with the hydrocarbon based heat transfer fluid. 
     
     
         7 . The aircraft hydraulic system set forth in  claim 2 , wherein the friction modifier is a fatty acid. 
     
     
         8 . The aircraft hydraulic system set forth in  claim 2 , wherein the friction modifier is a carboxylic acid. 
     
     
         9 . The aircraft hydraulic system set forth in  claim 2 , wherein the hydrocarbon-based heat transfer fluid is a synthetic hydrocarbon-based heat transfer fluid. 
     
     
         10 . The aircraft hydraulic system set forth in  claim 9 , wherein the synthetic hydrocarbon-based heat transfer fluid is polyalphaolefin. 
     
     
         11 . The aircraft hydraulic system set forth in  claim 2 , wherein the hydrocarbon-based heat transfer fluid is mineral-based. 
     
     
         12 . The aircraft hydraulic system set forth in  claim 2 , wherein the heat transfer fluid has a viscosity of about 1100 centistokes or less at negative sixty-five degrees Fahrenheit. 
     
     
         13 . The aircraft hydraulic system set forth in  claim 12 , wherein the heat transfer fluid has a viscosity within a range of about 500 to 1100 centistokes at negative sixty-five degrees Fahrenheit. 
     
     
         14 . An aircraft hydraulic fluid comprising:
 a heat transfer fluid; and   a friction modifier.   
     
     
         15 . The aircraft hydraulic fluid set forth in  claim 14 , wherein the heat transfer fluid is hydrocarbon-based. 
     
     
         16 . The aircraft hydraulic fluid set forth in  claim 15 , wherein the friction modifier is a fatty acid. 
     
     
         17 . The aircraft hydraulic fluid set forth in  claim 15 , wherein the friction modifier is a carboxylic acid. 
     
     
         18 . The aircraft hydraulic fluid set forth in  claim 14 , wherein the heat transfer fluid is polyalphaolefin. 
     
     
         19 . The aircraft hydraulic fluid set forth in  claim 14 , wherein the heat transfer fluid has a viscosity of about 1100 centistokes or less at negative sixty-five degrees Fahrenheit. 
     
     
         20 . The aircraft hydraulic fluid set forth in  claim 19 , wherein the heat transfer fluid has a viscosity within a range of about 500 to 1100 centistokes at negative sixty-five degrees Fahrenheit.