The Klinkhammer Fly was devised by a Dutch angler Hans van Klinken in the early 80’s to imitate an emerging caddisfly.
Klinkhammers are different from many other parachute dry flies in that the thorax of the fly is designed to hang down ‘through’ the surface of the water to imitate an emerging insect. 
The abdomen serves as a trigger point which penetrates the surface film, which gets noticed by trout from great distances, even before any resulting surface footprint features. In all variations of this fly, the abdomen of the fly is underneath the surface of the water to attract the fish and improve hookups, while the parachute hackle and foam or wing is on or above the surface of the water for visibility and flotation.
Fly Tying Recipe: The Klinkhammer Special
Note: Change the colors to match the naturals
Hook: Orvis Czech Nymph Hook, size 12
Thread: Black, 6/0
Post/underbody: White polypropylene yarn
Body: Tan Super Fine dubbing
Thorax: Peacock herl
Hackle: Ginger dry-fly hackle, slightly oversize