Morgans wrote:
"TJ400" wrote in message
oups.com...

AOA, L/D, Clmax and LE slats are what exactly?.... Been out of the
whole sport aviation for some time and just trying to grasp it all over
again..

thanks..

http://www.home.earthlink.net/~tp-1/a4412-a.jpg
http://www.home.earthlink.net/~tp-1/a4412-b.jpg

Earthlink is so messed up right now it's almost unusable.

I posted these two charts, but EL tells me the images cannot be viewed
because they contain errors.

WSFTP had no trouble showing them - so I dunno....

Two charts of airfoil performance data for the 4412.

Notice (I hope) that the flaps deployed curve is similar in shape as the
no-flaps curve, but a little taller and broader at the bottom.

Interpret that as Higher CL at any given AoA.

Power off, the wing will stall at some partiular AoA.

I usually look for that initially between 10 and 12 degrees (depending
on the airplane).

I've also noticed that many common airfoils actually have a
_lower_ stall AoA with flaps down!


Like in a 172, notice the way the nose comes down with flaps?

We are operating at a higher CL now and need LESS AoA to make
the same amount of lift. Has to do with the increase in Camber
with flaps down, I believe.

That indicates a NARROWER range of AoA (flaps down compared to flaps
up)- not higher!

Power ON will allow for higher AoA, and thus higher CL.

How much higher depends largely on how much power can be applied (while
maintaining control of the aircraft at extreme AoA!)

However, do consider the possible results of a super slow approach
speed. Gusts have a much more profound effect on the amount of lift
generated (or suddenly lost?).

As would an unexpected loss of power...

This is flying pretty close to the edge, kids.



Richard