Can't find information about air launched torpedoes detection range:

In Hakuryo have 8km torpedo, and want to know they can be stealt dropped as her carring aircaft has 6,1 km detection range.
I wonder how far detected when her launching planes won't detected. Launched 7,5 km or something and turn with a plane to avoid 6,1 km detection.
Of course this can't work if "only torpedoes" detected (planes hidden with stealth) when touch the water in 7,5 km.

Can somebody confirm how air launched torpedoes detection work in the new CV rework?