System and method for forming elongated perforations in an inner barrel section of an engine

A method of fabricating an engine inlet of an engine, the method comprising:

• providing an engine inlet barrel section configured as a composite sandwich structure having an inner face sheet, wherein the providing the engine inlet inner barrel section comprises providing the engine inlet barrel section as a one-piece composite sandwich structure cured in a single stage;
• robotically drilling, using a plurality of synchronized robotic drilling units, a plurality of elongated, non-circular perforations in the inner face sheet after final cure of the composite sandwich structure, wherein the robotically drilling comprises indexing a hole pattern of the elongated, non-circular perforations to one or more cell walls of a honeycomb core of the composite sandwich structure, and positioning the hole pattern of the elongated, non-circular perforations such that each of the elongated, non-circular perforations is located at a spaced distance from the one or more cell walls;
• and
• forming the plurality of perforations in a quantity providing a predetermined percent-open-area of the inner face sheet.

A method of fabricating an engine inlet of an engine, the method comprising:

• providing an engine inlet barrel section configured as a composite sandwich structure having an inner face sheet, wherein the providing the engine inlet inner barrel section comprises providing the engine inlet barrel section as a one-piece composite sandwich structure cured in a single stage;
• robotically drilling, using a plurality of synchronized robotic drilling units inside the engine inlet barrel section, a plurality of elongated, non-circular perforations in the inner face sheet after final cure of the composite sandwich structure to provide a percent-open area in one section of the inner face sheet that is different than the percent-open-area in another section of the inner face sheet, wherein the robotically drilling comprises:
• indexing a hole pattern of the elongated, non-circular perforations to one or more cell walls of a honeycomb core of the composite sandwich structure;
• positioning the hole pattern of the elongated, non-circular perforations such that each of the elongated, non-circular perforations is located at a spaced distance from the one or more cell walls;
• and
• using the plurality of synchronized robotic drilling units to elongate each of the elongated, non-circular perforations with respect to a longitudinal axis that aligns with a flow contour line of airflow through the engine;
• forming the plurality of perforations in a quantity providing a predetermined percent-open-area of the inner face sheet;
• and
• indexing the engine inlet barrel section and the plurality of synchronized robotic drilling units to at least one fixture supporting the barrel section.