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Edges control which way radar waves scatter. So stealth aircraft try to keep them running in as few directions as possible, such as on the B-2 which has just two.

B-2 4-view

However, it seems to me there is another factor. Since an edge acts as a line source, it is important that it is as long as possible to reduce diffraction of the emitted beam.

In this respect the B-2 seems deficient. Whereas it has 12 edges of varying lengths, the X-47A has just four (or five if you count the tailpipe).

X-47A 3-view

Despite the aircraft being smaller, the shortest edges don't look about the same as the shortest edges in the B-2 (if you count out the tailpipe). Thus, if my line source assumption is correct, those edges should have no more trouble with diffraction than the B-2.

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  • $\begingroup$ The diamond shape is to make most of the lines parallel, so that the non-stealth directions are minimized. In the case of the B-2, since the direction perpendicular to the main wing's front edge is definitely not stealth, so why not aim the non-stealth direction other edges to this direction, so that they don't contaminate other directions? $\endgroup$ Commented Apr 13 at 13:21

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In short: Broadly yes, but it's not necessarily important.

Radar operation is complex, stealth more so. Edge diffraction is just one of many mechanisms that can break it. There's 10 main factors usually checked in simulation, and multiple others less-well-studied.

reflections

Actual RCS is checked in anechoic chambers, and even then it's a series of 3D plots (or 6D if you consider non-static) rather than a single number.

Simulation plots usually look like this (and there's a lot of them - but a lot more in chamber testing):

Sim results

To the question's core, stealth design involves managing the number of reflection lobes. 2-lobe (X-47 and B-2) is technically better than 4-lobe or 6-lobe in newer designs. Longer edges are also better. But it's a part of a large pool of reflections and doesn't alone decide the result.

The F-117, designed based on Physical Theory of Diffraction, has famously proven to have a higher RCS than predicted. Its stealth generally relied on jammers; two were hit by radar systems in 2000 when those lapsed. It's not "stealth doesn't work" as much as it's "objects in the mirror" - the B-2 and the F-22 are far better in this regard.

Realistically, as of 2026, with IR and counter-stealth technology developing, it's likely that absolute minimization of X-band signature would be deprioritized and only done to the extent that it doesn't significantly compromise other characteristics.

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  • $\begingroup$ Just because it's unbelievably cool looking - do you have one of those cool 3D heatmap visuals for the B-2? $\endgroup$ Commented Apr 15 at 15:25
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    $\begingroup$ @ConnieMnemonic Sadly not. The B-2 is still heavily classified, there's almost nothing to go on except general plans and photos, and it has RAS that are hard to model. $\endgroup$ Commented Apr 16 at 6:54
  • $\begingroup$ ty anyways my man! $\endgroup$ Commented Apr 21 at 9:58

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