The later "buckler" bow wall was described (in SoS) as "a much smaller, circular shield, its diameter less than twice the ship's extreme beam. It offered no protection against beams coming in from acute angles, and a laserhead could actually slip right past it before detonating."n7axw wrote:IIRC, bow and stern walls developed in two stages. The first completely sealed up the end (bow or stern). Oversteegen had the earlier stage when he was at Refuge with Abby. He had to cut power to use the stern wall. But the newer stuff, the Rolands, the Sag Cs and up all have the later stage wall which permitted the vessel to continue accelerating with the wall activated. These walls cover most of the bow or stern but leave enough open to allow the vessel to move under power. Conceivably a laser could slip past this wall, but the possibility of it doing so is low.
Don
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Actually crunching the numbers, and assuming it's the same 10 km away as the sidewalls, it only protects the whole ship from shots occurring within about 1/6th of a degree from dead ahead. Any more than that and there's a perfect angle to skim past the forward buckler and hit the top rear of the aft hammerhead. It's better than nothing against laserheads, and it's be devastating in an energy range chase against a single opponent. But against even a pair of enemies, or a lot of missiles, it's a minuscule shield to try to hide behind.
(It might make sense to have that closer to the ship than normal sidewalls. You get less protection from each hit, but you block more angles hit could come from. The covered angles scale approximately linearly with reduced standoff distance. Cut standoff in half and cover about twice as wide a set of angles. Still pull it back to the probably ineffective 100 meter standoff and you're only covering about 9 degrees +/- from dead ahead. Even the aft wedge opening gives a much larger angle of visibility than that)