The source of the idea that the Horten was a stealth aircraft is the oft-repeated ‘fact’ that the Horten would have been 30% (or 40%, or 80%, depending on who you ask) less visible to UK radar (but not anyone else’s).

For some reason (probably because it made for a better story) Northrop and/or National Geographic modelled it at great expense using ‘Battle of Britain’ period Chain Home frequencies (6 to 13m wavelengths), which later sources assumed to be contemporary. These were obsolete at the time of the Horten’s appearance, and had been long superseded by the AMES 7 GCI system, of a much higher frequency. I have just edited Wiki.

Was it in fact stealthy at all?