How much clearance should the launch tube have when the target is 500-900 meters away?

• A. 6 inches
• B. 30 inches because of wire sag
• C. 36 inches
• D. 18 inches

Answer: (B)

Wire sag is the key idea here. When a guided missile runs on a tethered wire, that wire sags as it stretches between the launcher and the target. To avoid the wire contacting the target or surrounding terrain during the flight, you must provide a vertical clearance at the target that matches how much the wire will droop at the given range. At distances of 500–900 meters, the sag is substantial, so the prescribed clearance is 30 inches. This margin allows the wire to droop without fouling the target or the flight path, giving safe, reliable operation. Smaller clearances won’t compensate for the sag, while a much larger clearance isn’t necessary for this range.