# Ra-Aus BAK Exam

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Brodie, if you want to choose any advice from this side track from the original question, I'd recommend taking the advice of djpacro; he's a very experienced aerobatics instructor who has won international awards.

However, in view of the way this thread has been derailed, forget about any examples; my main message was to study until you understand everything in the BAK sylllabus because BAK contains the building blocks that your flying will be based on. If you do that you will not only pass the exam, but have skills to help you when something happens that you didn't expect or hadn't experienced before.

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In a similar situation,  not over water but at high density altitude I took the option of a low level (very) carefully executed balanced turn  staying in ground effect. Flaps would have reduced the radius of the turn had space not been available over level ground but flaps have a lift and a drag function and some simple flap designs are not very efficient at producing extra lift.

It's the margin of power over drag that permits climb has always to be remembered.. Ground effect provides extra lift without drag penalty or put another way, the same lift with LESS drag.. When flying up a valley you get no opportunity to use ground effect so you need enough room to do it. That's why you don't fly up the middle of it. Not getting yourself into these situations is the best approach to flying.  Nev

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We all know from our BAK  that wings stall at about 16 degrees aoa regardless of airspeed. So when we lower 30 degrees of flap to zoom over an obstacle and the main wing is at say 10 degrees aoa, why don't  the flaps stall and not provide much lift only a lot of drag ?.

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So when we lower 30 degrees of flap to zoom over an obstacle and the main wing is at say 10 degrees aoa, why don't  the flaps stall and not provide much lift only a lot of drag ?.

Some flaps do provide mostly drag and little lift at high angles of deflection.

But to  answer your specific question, the effective chord line for AOA reckoning is found by an imaginary line joining the T/E of the wing to the centre of the L/E nose radius. In the case of flaps, the line from the T/E of the flap to the L/E of the wing would be less than the 30º flap angle.

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