I can't provide links (for obvious reasons) but when working on a warship programme many years ago I had a very worried (and somewhat gullible) PA ask me for advice.
She had a letter addressed to a name she didn't recognise. So she had opened the letter and was even more worried.
IIRC it came from Prince Harold of England and gave us details of a secret design to prevent said warship being hit by a torpedo. The design consisted of a cylindrical cube that would rotate at high speed about one axis.
Naturally I realised the great importance of this design immediately and gave it to the mechanical engineers. Regrettably they completely failed me and never managed to provide me with a rotating cylindrical cube. I am sharing this with you all now but I must pass on the restriction Prince Harold implored me to obey - don't tell the French