No kidding... today I departed maybe 30-60 secs later (I wasn't counting- just followed ATC clearance) and just as I rotated there was a sharp yaw. It had to be wake turbulence. The intensity was quite suprising and would have been more so had I not been almost airborne.
Even a C152 produces noticeable wake turbulence. A good indication that the students perform well at doing steep turns is that they hit their own wakes upon completion of the turn.
A good indication that the students perform well at doing steep turns is that they hit their own wakes upon completion of the turn.
Not really - it means that they lost about 20ft. ;-)
The wake vortices are said to descend at about -300fpm (initially) so if you hit your wake perfectly after a Rate 1 turn all the way round, you have descended at least 300 feet 
That doesn't sound real because I have definitely hit my own vortices when doing this.
Yes, but steep turns are not rate one. And I have yet to see a student (or experienced pilot during a checkride!) who does not lose a few feet during those - after all, 100ft are allowed for a pass.
Wait until you hit the wake turbulence of a B747 :) Not something I would care to repeat. It was like flying into a brick wall.
A friend of mine (now sadly deceased in an aircraft accident) back when wake turbulence wasn't well understood and jet airliners were new hit wake turbulence in a light twin on approach, which turned him upside down while at fairly low altitude (I don't recall how high he said he was, but it was low enough that the ground looked big and scary). He had some aerobatic training and realised the only way out was to keep the roll going till he was upright again. His passengers had large laundry bills.
I have always tried to visualise the moving patterns of the w.t. when behind larger aircraft and so far have not encountered anything from them. But a few weeks ago, on final in a Piper Cub behind a C172, I was surprised by a sudden 45 degrees roll. Before that, I would have been sceptical of any report on w.t. behind a DA-40 with its low wing loading and high aspect ratio. But if a C172 can make them, of course a DA-40 can as well.
