Nearly 2 years ago (before we got a badly needed update of our WT rules), I got to see what the wake of a Sea King HC.4 does to light aircraft. The SK departed on the paralell TWY (close to the runway) and a Grob 115D made a TGL on the runway 1 minute later.
The Grob rolled aprox 45 degrees right (away from the TWY) when at 50ft, and was "lifted" 100 meters in the same direction horisontally.
Scary, especially since there is woods and a HAS farm on that side of the runway..........
Today the controller that was working then, agree that the rules update was badly needed as well
(We needed to apply WT sep between departures, but not departures and TGL when VFR, only to caution. Scary!)