Method of manufacturing a cooled turbine blade with dense cooling fin array

A method of manufacturing a turbine blade for use in a gas turbine engine, the method comprising:

• forming an inner blade pattern with a water soluble material, the inner blade pattern including an inner spar and a plurality of inner spar cooling fins, the plurality of inner spar cooling fins radiating outward and away from each other on opposing sides of the inner spar, wherein the plurality of inner spar cooling fins have a density of at least 80 fins per square inch on each opposing side of the inner spar;
• forming an inner blade core, the inner blade core substantially encompassing the inner spar and the plurality of inner spar cooling fins of the inner blade pattern;
• removing the inner blade pattern from the inner blade core including dissolving the inner blade pattern with an aqueous solution and leaving a mold of an inner portion of the turbine blade;
• forming an outer blade pattern, the outer blade pattern substantially encompassing the inner blade core, the outer blade pattern including an airfoil and a base, the airfoil including a tip wall, the base including a platform and a blade root;
• forming a casting shell, the casting shell substantially encompassing the outer blade pattern;
• removing the outer blade pattern from the casting shell;
• casting the turbine blade in the casting shell;
• removing the casting shell from the cast turbine blade;
• and
• removing the inner blade core from the cast turbine blade including dissolving the inner blade core in an alkaline solution.