> ... reportedly was to use the aircraft to drop rats
> and insects infected with bubonic plague, cholera,
> typhus and other diseases on U.S. cities.
I didn't see the whole History Channel show on these
subs, but they interviewed one pilot who claimed his
mission was to attack the locks at the Panama Canal.
Whatever the use, the planes sure look as if they are
configured for one-way use (no recovery at sub, other
than ditching).
The link in Post 7 describes them as float planes. Thus they would have had the capability of landing on water and being lifted back on board with the collapsible crane.