A lacrosse head is provided that includes a base and two sidewalls connected to the base. If the actual link attenuation is less than the precalculated attenuation in the absence of multiple missile plumes, no attitude change is commanded. An opening for a camera lens is provided in the covering cap. The intruder might try to defeat the pressure action of the doorknob, by sliding a thin piece of cardboard or other thin material under the door in an attempt to push the security bar base away from the door, causing the bar to fall. The cathode recuperator section is located adjacent to a first edge surface of the anode recuperator, and the air preheater section is located adjacent to a second edge surface of the anode recuperator section.