Archery, Arrows & Arrow Flight — There is a critical distance at about 5 to 8 metres. If the arrow hits fetching end "up", the nocking point needs to be lowered, and if it hits tail end down, the nocking point needs to be raised.
Archery, Arrows & Arrow Flight - This page has a long discussion of flight mechanics and some good information about tuning up a modern recurve bow. Some of the information is also applicable to traditional longbows (but not the part about sights and buttons, of course). Pinning for reference to read more fully later.
Archery arrows port orford cedar medieval style by PodunkHollow