HALO inverted on pole.
HALO inverted on pole.

High fidelity radar cross section (RCS) testing of HALO has validated the accuracy of the predicted F-35 stealth signature performance over a broad elevation and frequency range.

HALO pole model

Janicki Industries, a Washington, USA, based engineering company that creates composite tools, prototypes and production parts, worked as a key partner with Lockheed Martin throughout the development and fabrication of the HALO pole model, beginning in 2006.

The demanding timeline for F-35 development drove several innovations during the project, including building a structural inner body in advance of final surface engineering. By building the centre-body concurrently with the aircraft engineering phase, the Janicki/Lockheed Martin team was able to start building the model more than a year in advance of receiving the final surface geometry.

Once the external shape of the model was established, Janicki applied a surface to the centre-body using a proprietary technology developed by its tooling engineers. This began by applying sprayable, expanding urethane foam to act as a foundation. The foam was machined, then covered with a material developed by Janicki for the project. To address the entire surface of the model’s body in just two set-ups, Janicki’s largest machining centre was used.

After completing the model’s body, Janicki began developing and producing external composite panels for the pole model. These panels were fastened to the finished body to replicate the F-35 aircraft for testing purposes.

The panels required the strictest adherence to every design aspect so that the model would match the aircraft’s real production specifications. Janicki produced highly accurate moulds to fabricate the composite panels. After panel fabrication, Janicki converted the moulds to specialised trim and drill fixtures, which is said to have resulted in significant cost savings for the F-35 project.

Janicki assembled major portions the final model, including wings, engine mounts, internal structure and inlet duct assembly.

During testing, the HALO model is rigged in a variety of orientations on the top of a test pole. The model is configured for either upright or inverted orientation on the pole. This requires it to be re-configurable both structurally and cosmetically to accurately represent the airframe in either orientation.