OK, I have arrived at a station with a distress beacon, clean, and got attacked. I launched the sos baecon and 4 vipers turned up but I was shot up before they did anything other than fly around in tight formation with blue lights flashing
Next time I remembered to carry some cargo

and got a more enthusiastic attack -- fired beacon -- this time a considerable battle ensued with 8 Vipers and me (I was thanked for the assistance)
vs a Mamba (that I shot down for
¢174 bounty) and his insane cronies -- I did sustain some damage -- manual docking under heavy fire & still "clean" so I didn't hit any old ooze by mistake: the distress beacon seems to work fine
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distress beacon is here
Missiles and Bombs v2.2.oxp
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(although this isn't exactly what's being discussed here, it
does elicit the desired response and behaviour from vipers)
hope it's of some use to someone!