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Comment by quanto | Hacker News Reader

The whole mirror analogy for angular facets breaks down when you realize airplane is a moving object and at some point in its trajectory, one of the facets is likely to be facing the radar (maximum cross section).

If I remember from my numerical analysis days, it was the ease of numerical computing that necessitated the facets. Think 3D graphics from the 90s. All polygons.

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My understanding is that this more of a tactical consideration than a technical one. When these planes were used in the Gulf war, they were absolutely detected by Iraqi radars; they were just detected too late to do anything about them. While these planes were approaching the radar stations, they were oriented in one relative direction so the radar waves could be scattered away from the source consistently. Source is the Ben Rich Skunkworks book.

Your answer shows why flat surfaces were acceptable for a bomber (with an asterisk) given the constraints.

Then, the question becomes why is the B-2 bomber (and latest stealth fighter jets) not angular like F 117.

Scientific computing has come a long way since the days of F-117. We do not need flat surfaces to scatter the beams away. Finding optimal curved surfaces that scatter the beams away is just a harder math problem.

3d graphics is still mostly polygons, just much smaller?

Anyway, I'd imagine the part that is an integral over the surface becomes a finite sum, the post doesn't say but it seems like a reasonable guess.

The primary design goal of the stealth mechanism is to get to the target undetected. By the time a radar signature shows up, the aircraft have ideally already dropped their bombs.

Being detected too late might as well be the same as not being detected at all in most practical scenarios.

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