I just couldn't figure it out. I am sure plenty here do know but what the heck was that sharks fin on those old WWII aircraft pitot tubes for. And when I did ask several people involved with warbirds, they didn't know. Only thought about it occasionally but wondered for years. Google searches didn't help. But I finally took an IFR groundschool to renew my rating which had lapsed(long story as I had one in another country) and they had a slide with a cutaway of one of those old pitot tubes with interior parts labelled. Then I had the information to google pitot tube riser and got the explanation.
I know, I am rambling on but for those that ever wondered why there is a sharks fin on some of those old pitot tubes....
google it or look at this link....
https://books.google.ca/books?id=bMwIAQ ... er&f=false