"Morgans" wrote in message
...

"Peter Dohm" wrote

I don't fully understand the theory on those either, although they
certainly seem more promising than the older method of degrading the
inboard portions of a wing to achieve the desired progression. If anyone
has experience and/or theoretical knowledge, I beg to be enlightened.

A piece of triangle on the inboard leading edge do not hurt the airfoil at
cruise, noticeably.

Think about it. If you put it on the leading edge where the air is
splitting going up or down, what difference would it make? Once the angle
of attack increases too much, then it causes the air to start burbling,
and lit you know to back off a bit. Sounds good to me!
--
Jim in NC

Jim, I think you may have read my question and statement too hurriedly.

I agree that the traditional "stall strips" have negligible effect on the
wing in cruise. However, in the slow flight regime, they only cause the
inboard portions of the wing to stall at a higher airspeed. In some cases
the degradation can be dramatic--as in the case of the Piper Tomahawk where
the version with 4 stall strips stalls at approximately 10% higher airspeed
than the version with 2 stall strips. (I am sorry that I can't locate the
POH to quote precisely)

The question, on which I begged enlightenment, was the preformance of the
little "delta" shaped vortex generators which are dewsigned to be placed as
a forward projection of the leading edge with the tip downward and their
widest portion at the top. Unlike the moveable slats on the Helio and the
fixed slats on the Swift, which work by enhancing the Coanda effect, the
leading edge vortex generators are open at the sides and create a double
vortex at high AOA and have negligible effect in cruise. Most of what I
think that I know about them is from hangar flying, and the builders/pilots
who have them seem to like them, but I still don't know whether the actual
stall speed is increased or decreased--although the stall is supposed to
occur at a slightly higher AOA.

Clear as mud, eh!
Peter