wrote:
You may want to keep an open mind on this. There are experimentally
documented cases where VGs not only decrease stall speeds, but also increase cruise
speed. Doesn't seem intuitive to go faster by adding draggy looking things, but it
turns out the more laminar airflow they provide decreases drag by more than what they
add.

I've had AMR&D's VGs on my Cherokee for about 8 years. I spoke at length
with Art Mattson when I first got them. Here's the theory... The
inboard section of a Cherokee is not very aerodynamic. In fact, on the
slower Cherokees, it's almost always riding just above a stall. The air
is fairly turbulent going over that section of the wing. The VGs create
small sideways vortexes that enhance the laminar flow of that section of
the wing. As a result, there's less turbulence and drag in that area of
the wing during cruise. Art fully admits that the theory isn't as valid
on Cherokees that are already faster.

Anyway, I installed a lot of different speed mods on my 140 at the same
general time, so it's hard to say what did what (nor do I care). My 140
does tend to be about 15-20 mph faster than the average 140, plus it
handles really well at low speeds.

--- Jay



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