I too am just finishing my 40 hours of phase 1 on Lancair IV N94PT (no
pressure, TSIO-550). I started with 10 inch long stall strips (triangles
of plastic about 3/8 inch on a side taped to the leading edge) mounted 15
inches outboard of the wing/fuse joint. They were mounted at the leading
edge stagnation point (as best as Charlie Kohler could eyeball it), eg at the
tangent point of a vertical line with the plane level. I took some stall
data in this config and then removed the strips and repeated. With the
strips I had about 5 KIAS of warning and never actually experienced a developed
stall as I initiated recovery at the buffet. Without the strips I
experienced an abrupt right bank of about 45 to 60 degrees. Forward stick,
a little aileron against the bank and the recovery was positive
and immediate with a few hundred feet of altitude loss. There was no
aerodynamic warning prior to the stall, at least none that was useful.
Power was idle, ball centered, CG forward for all stall tests. I did
both 1 G and accelerated stalls, clean and configured, light (~2600#) and
moderate (~2850#) weight. The speeds varied some but the characteristics
were consistent.
First indication of buffet, 1 G:
without strips, light:
Vs: 73 KIAS, Vso: 68 KIAS
without strips, moderate:
Vs: 77 KIAS, Vso: 72 KIAS
with strips, light:
Vs: 78 KIAS, Vso: 70 KIAS
I have set my Chelton warning (Vs) at 80 KIAS so it doesn't always come on
at touch down but does provide a reasonable comfort zone prior to
stall. I have not decided whether I am going to reinstall the strips prior
to paint.
regards, paul