Pilot DAR. Question. Many years ago I was a QFI flying, among other types, RAAF Dakota aircraft. Practice stalls clean on the Dakota posed no problem. However in the approach configuration (full flap and approach power) in every case there was a sharp wing drop beyond 45 degrees and considerable altitude lost before full control was regained.
A former UK test pilot on Pprune made the point that if the stall was approached at one knot per second the wing should not have dropped unduly. While I recall we didn't reef the nose up to reach stall speed and the rate of speed decay was certainly faster than one knot per second nevertheless why would a savage wing drop occur with landing flap extended but not so in the clean configuration? Rate of speed decay was about the same clean or flap down but more than one knot per second.
The worst wing drop I ever experienced was not in a stall but at 200 ft after takeoff in a Dakota which was fitted with the usual rubber de-icing boots on the length of the wings. Just as the landing gear was retracting the starboard wing suddenly dropped without warning. Almost full aileron was required to level the wings along with some rudder. Weather was good with only light winds. A glance out of the pilots window revealed the deicing boot from the landing light out to the wing tip had split asunder and flapping everywhere. The loss of lift on that wing was marked.
The student in the left seat thought the starboard engine must have failed and tried to feather the propeller. Fortunately I was able to stop his hand as he reached for the feather button as engine instruments were normal.
I was concerned that using flaps for landing might produce more unexpected control difficulties so I elected to make a flapless landing As speed reduced during the flare and float the wing dropped and we touched down just as we ran out of aileron. An interesting experience.
Last edited by Judd; 23rd Aug 2020 at 10:16.