In article ,
Todd Pattist wrote:

(drake) wrote:

there is a HAL HPT-32 (pistonengined 2 seater trainer light a/c)
which, when attempting a stall, does not pitch down correctly. Instead
one of the wings (either port or starboard (50/50)... no gyro problems
due to engine) almost always drops, and this genreally results in the
a/c entering a spin

A strong wing drop that occurs on either side can be caused
by the wing tips stalling too early. As the tip stalls, the
wing with the stalled tip begins to drop, the AOA increases
on the dropping wing and the entire wing stalls. Washout
(wing twist to reduce tip AOA) or a carefully selected
airfoil for the tip (that stalls at a higher AOA than inner
parts of the wing) may be used by the designer to prevent
this undesirable phenomenon. Careful comparison of washout
angle and/or the airfoil at the tip with the plans might
detect some rigging or construction problems. Any tendency
of the wing to twist, while in flight, can exacerbate the
problem.
Todd Pattist
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If the wing drop is 50/50 L/R on the same plane, I would think that
somebody is holding in a little aileron or rudder, without knowing it.

I am not familiar with the type, so I cannot speculate further.

I would attach some stall strips to the inboard leading edges of both
wings, so they would induce turbulence at high angles of attack. They
need be 4" to 6" long, which would induce root stall before tip stall.