Large Composite RF Test Body
Aerospace and Defense. Low signature RF test structure.
Previous Limiting Technology
Materials used in the manufacture of previous test bodies lacked durability, resulting in limited service life. Cost was prohibitive due to tight tolerance requirements that drove the creation of high accuracy tooling, which was as much, if not more expensive than the final manufactured part.
The customer had the concept of a large 20 ft x 10 ft x 12 inch test body with tight tolerances, small deflection and exacting surface profiles. The project goals included a durable test asset with improved service life at a significantly reduced cost. The final design, manufacturing technique, and test verification was unknown and left up to Rock West Composites.
Rock West determined that the test body must be lightweight and have high stiffness to counter act gravity sag. To increase stiffness, structural ribs were made of ultra-high modulus carbon fiber honeycomb sandwich panels. The core of the body was constructed of foam with carbon fiber skins. By using digital manufacturing technology, RWC was able to machine the foam to high accuracy. The company was able to bypass tooling costs entirely, while still meeting 0.050″ surface tolerance across the large flat and shaped areas, by doing material layup directly on that core. The special outer coating was RF absorbent over a conductive layer. RWC also conducted structural testing to verify that the test body could meet its service loading requirements. There were many significant costs savings by using carbon fiber skins, the test body is more durable than previous materials and has a longer service life.