“Panther Beast” is a competition organized by the 63rd Fighter Squadron at Luke Air Force Base. The name comes from the 63rd’s nickname (Panther) and the fact that missions were flown in “Beast Mode.” Beast Mode is not an official or technical term. At least not within the U.S. Air Force. However is a pretty common way an F-35 configuration involving both internal and external weapons loads is dubbed.
When the F-35 carries all of its weapons internally, it maintains its low observability or “stealth” capability. This is a critical asset during the earliest phase of a conflict when combat aircraft are operating in a non-permissive environment with threats like surface-to-air missiles, automatic radar guided anti-aircraft guns and enemy aircraft. The F-35s low observability and internal weapons bay enable it to operate with greater autonomy in this high-threat environment. Once the surface-to-air and air-to-air threat is moderated the F-35 can begin to prosecute targets using externally carried precision strike munitions that will increase the aircraft’s radar signature but are employed at a time when enemy air defenses have been suppressed and are less of a threat to aircrews.