Re: Canard loading?

[Alan Shaw <wingco@iu.net>]

Brian,

what is the wing loading of the canard in level flight at max gross?

Good question.  The canard has aprox twice the wing loading of the main
wing.  That's the way all canards and flying wings work.  They have to
be nose heavy for stability but not so much that control is limited.

> What is the area of the canard?

Measure it.  It's 1.5' x aprox. 16' = 24 sq ft.

> What is the area of the elevator?

40% of the canard cord.   Don't include the tips .4 x 15= 6 sq. ft.On my
STD-300 hp the canard is only 13.5' long (with tips) to move the over
all center of lift back for the new CG.  The 6" canard tips are part of
the elevator so as to not loose area there.  Note: this mod makes for
sensitive pitch control that could precipitate PIO's

If you caluculate the area of the main wing plus strake and add the
canard area times two then divide this into your gross weight you can
find out how much each wing is carrying.

The center of lift for most airfoils at high angles of attack is 28%
back from the leading edge.  But this rotates back some at higher speeds
and lower angles of attack.  These "rotational moments" are one of the
big factors of airfoils in design.  As you can see, as we slow down, the
lift moves forward which has the same effect as if the CG moved aft
which is not a good thing when you are a student in a conventional
airplane with a tail wind turning base to final with the stick and
throddle all the way back feeding in left rudder and aileron.  This is
why in a canard we load it up and let it  mush stall well before the
main wing ever could.


Alan