Launch pad flame deflector structure and method of making the sam

Abstract

Flame deflectors for rocket launchpads have historically been constructed on-site by spraying on a layer of refractory cement material, resulting in large monolithic structures which lack durability and are vulnerable to degradation by ambient weather. By assembling together a plurality of metal modules and refractory material modules, one obtains a flame deflector structure whose set of modules is matched to an expected heat distribution pattern of the exhaust from the rocket to be launched. Further, modules can be prefabricated at another location, under controlled conditions, and subsequently installed. In case of damage during a launch, any damaged modules can be swapped out and replaced by new modules, thereby minimizing cost and downtime before a subsequent launch event. The modules can be made more weather-resistant by applying an epoxy sealant to their rocket-facing surfaces.

What is claimed is: 
     
         1 . A flame deflector adapted for use during firing of a rocket generating thrust in excess of ten thousand pounds (about forty-five hundred kilos), said flame deflector having a metal understructure,
 a generally concave rocket-facing metallic surface ( 6 ), and at least one layer of refractory material affixed between said generally concave metallic surface ( 6 ) and an exhaust plume from said rocket,   wherein said refractory material comprises:   a plurality of refractory material modules ( 2 ) placed side by side on said generally concave surface, a sheet of refractory fiber material filling lateral interstices between said modules, and   post elements ( 8 ,  12 ) extending from rear faces of said refractory modules through apertures formed in said generally concave surface, thereby securing said modules to said surface, with sufficient strength to keep said modules in position, in spite of forces applied to said flame deflector ( 6 ) during a rocket launch.   
     
     
         2 . The flame deflector of  claim 1 , wherein each of said refractory material modules has a rectangular front face, four side faces, each orthogonal to said front face, and a thickness in a range of 10-20 centimeters. 
     
     
         3 . The flame deflector of  claim 1 , further comprising at least one module of highly thermally conductive metal material, arranged alongside at least one of said modules of refractory material. 
     
     
         4 . The flame deflector of  claim 2 , wherein
 said front face of said refractory material module consists essentially of a phenolic ablative material having a specific gravity about 1.3 and a Shore hardness value about 90.   
     
     
         5 . The flame deflector of  claim 2 , wherein
 said front face of said refractory material module consists essentially of a calcium aluminate cement containing about 40 percent hard alumina aggregate particles.   
     
     
         6 . The flame deflector of  claim 2 , wherein said front face of said refractory material module composed of a mixture of 40-60% aluminum oxide, mullite, 2.5-10% Christobalite, and 10-20% other components. 
     
     
         7 . The flame deflector of  claim 2 , wherein
 said front face of said refractory material consists essentially of Portland cement.   
     
     
         8 . The flame deflector of  claim 2 , further comprising
 a high-temperature-tolerant coating, resistant to infiltration of water, applied to said front face of said refractory material module.   
     
     
         9 . The flame deflector of  claim 7 , wherein said coating consists essentially of an epoxy sealant. 
     
     
         10 . A method of making a rocket launchpad flame deflector, which is resistant to degradation during a rocket launch, comprising the steps of:
 forming a plurality of modules, each with a metal substrate ( 5 );   covering said substrate ( 5 ) with a layer of expanded metal ( 4 ); applying a slurry of refractory material on top of said expanded metal layer ( 4 );   drying said refractory material in a heated environment to drive off free water, hydrated products and chemically bound water;   applying a seal-coating of epoxy sealant to an outer surface of said refractory material to create a refractory module; and   securing a plurality of refractory modules together, side-by-side, to form said rocket launchpad flame deflector.   
     
     
         11 . The method of  claim 10 , wherein said drying step comprises drying each module in a kiln at a temperature exceeding 100 degrees Celsius until a weight-percent of water in said module is less than three weight-percent.