Wolfgang,

 

Regardless of what the NASA report says, they never flew the wing as implemented by Lancair.  Extension of the flap more than a few degrees beyond 0 does little for lift.  The pitching moment does change the attitude, but does not significantly change the stall speed (a few knots is not significant).  The drag addition is significant.  The AOA is another story.  While the attitude changes with flap extension, the AOA is still high and slower speeds just brings one closer to a stall, thus reducing margins to take care of loss of pilot attention, wind shear, distractions and anything that leads to mis-application of up elevator with pitch sensitive controls.  It is very easy to reach critical AOA at slow speeds, with or without flaps..............

 

Scott Krueger 

 

-7 to -10 isn't going to make much difference in flight. If the latest manual says to use -7 then go for it.

 

The purpose of reflex flaps is to reduce drag (lets you go faster) while giving up some lift coefficient. At higher speeds you don't need that extra lift coefficient.

Reflex will also move the center of lift forward causing a nose up force affecting the trim needs.

 

For landing, you give extra flap to increase the lift coefficient (and the drag) so you can go slower without falling out of the sky.

 

See attached file for more details.

 

Wolfgang

 

 

----- Original Message -----

From: Ed Gray

To: lml@lancaironline.net

Sent: Saturday, April 14, 2012 12:01 AM

Subject: L320 flap setting

I have the exact concerns reported by Rob Stevens in Australia.  Since the manual is vague on cruise flap settings, can some experienced L320-360 fliers help us with what is the best cruise settings?  Is it -7deg. , -10deg., or somewhere else.  Since construction variances can create different “faired-in positions”, is there an angle which can be measured from the top or bottom wing surface?  Can anyone explain the aerodynamic reasons for reflexed flaps?  Rob and I need help!

Ed Gray Dallas  L360 N77ZG XP360 Silver Hawk injection MT 3 blade prop Dual Dynon Skyview SL30

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