Mechanics of Elevator Trim. In Detail.

On Jun 11, 12:45 am, Ron wrote:
On Tue, 10 Jun 2008 11:24:39 -0700 (PDT), Tina
wrote:

Thanks again. My intelligent but ignorant guess is designing canards
so that they stall first should not take a genius, but there may be
traps I don't see. The world is safe, though, since I don't design
airplane.

The landing issue you raised is pretty neat, since most of us --
especially Mooney drivers -- are careful about airspeed on final and
in the flare, and like to land with the wings almost stalled. But in
the case of a canard if that stalls first I think the airplane would
very enthusiastically want to pitch forward hard enough to bend the
nosewheel!

I haven't flown a canard, but my son has done a lot of flying in one
that was under development. You are right... you don't want to stall
the canard on landing. You fly it all the way to the ground. Three
problems with the canard, as my son saw it, was lack of forward
visibility on landing, drag from the canard in cruise flight (a fixed
canard has to have its AOA greater than the wing and enough surface to
generate lift) and ice shedding off the wings through the propelllor.
Piaggio solved the drag problem, partially, with a three surface
aircraft and a relatively small canard. I believe Beechcraft
attempted to solve it with a variable sweep canard, but I could be
wrong.



At least with the stabilizer still flying the nose might be able to be
put down more gently. You've provided some nice insights, thanks.

My son says canard landings are like the "Little girl with the curl in
the middle of her forehead"... when they are good, they are very very
good, but when they are bad they are horrid. :-)

Ron Kelley

Yes, it seems to me (again, ignorant of the reality) that the airplane
has to be flown onto the runway, rather than stalled onto it. When we
land the airplane is done flying, period, but flying it on means it's
fast enough to take off again.

The higher angle of attack causing drag in cruise trade-off is a bit
of a surprise since what is gained is aerodynamic positive lift from
those little wings in front of the airplane, instead of the negative
lift from those wings most of us have on the back end that are
increasing the aerodynamic load.

Fun discussion, thanks.