Thanks for the link. There's footage I've never saw anywhere before. In particular, that of the 'Flettner' dropping a depth charge.
It's a pity that my already elementary Russian is now so badly corroded that a real improvement would require perhaps a partial brain transplant... Apart from 'samolyot', 'avtogir', 'TSAGI', 'niemietsky' and -a very correctly pronounced 'Juan de la Cierva', I've got very little... Anyway, I am going to try a more conventional treatment, and I hope to get at least partial success... Russian is (and has been) a very important language,
Regards
Xavier