WWII aircraft with winglets?

The Curtiss SO3C Seamew with what appears to be early winglets. Did they have the same function as modern winglets, or do they have another reason?

 

another craft was the he 162 salamander, still unique to this day, do not really understand them

 

AFAIK they were not to serve the same purpose as modern day (Whitcomb) winglets.
Current ones effectively make the span infinite (stopping airflow round the ends of the wing and improving lift by reducing recirculation losses).
To the best of my knowledge the winglets as used during WWII were introduced as a measure to add dihedral to wings already in production (or couldn't have the necessary dihedral built-in for one reason or another) that were found to have insufficient stability during sideslip/ manoeuvre.
(From memory).

 

I believe the upturned wingtips of the Seamew were installed to cure instability and problems with handling. But did they have some of the features of modern winglets as well?

And the He 162 had wingtips turned downwards, what purpose had they?

 

Thet may well have had a peripheral effect like that Whitcomb winglets, but, as you said, they were installed to alleviate stability problems.
As for He 162 - dihedral or anhedral help stability, just in different ways.
The winglets on that aircraft gave anhedral.