Earlier, Robert Ehrlich wrote:

This will work on approach, when you have the nose down attitude
corresponding to the flaps setting but not in the situation of my
initial question, i.e. just after a botched flare, a few feet above
the runnway and no nose down attitude. In this case retracting the
flaps will cause a loss of drag, but no so huge, i.e. the drag will
much more than in zero flaps or zero spoilers configuration and there
is no gain in lift and no change in the stall speed, you don't have
the altitude that you can convert into speed, so I think that you are
going to fall on the ground, with a slighly increased delay compared
to what would happen if you didn't retract some flaps.

I have gone from plus 60 degrees to full negative, and then back to
plus 90, all within a few feet of the runway. It is rarely necessary
to do that (it sure wasn't when I tried it), but it can be done. All
it takes is speed, distance, careful modulation of pitch attitude and
a flare for the dramatic.

I think that what it boils down to is that everybody who has flown a
flapped aircraft knows that "sinking feeling" that you get when you
reduce the flap deflection, and most of them think that there's
nothing they can do about it. And that's wrong. If you apply the right
pressure to the stick in the right direction at the right time, you
can go from zero to full flaps and back again with no added or
subtracted vertical acceleration. This is, of course, slightly limited
by the longitudinal inertia of the aircraft; but is basically true for
all practical flap application rates. All it takes is practice.

Flaps are not magical lift-conjuring and lift-disappearing devices.
They are just a way of modulating the effective camber of the airfoil
section so as to change its L/D polar. All you need to do with the
stick is to adjust the angle of attack so as to maintain a constant L
value as you modulate the flaps to achieve the desired D value. And
that value can get very large indeed.

The only odd corner to flapped ships is that they, like most gliders
(all that I know of) stall at a higher speed with the flaps retracted
than with flaps deployed. So it is true that if you are just above
stall speed and you bring the flaps up, you could stall even without
changing the speed or loading. For example, the book values show the
HP-18 stalling at 35 mph at flaps 60, and 40 mph at flaps 0 (both at
770 lbs gross). However, it is expected that when you're operating
near the ground you have much more margin over stall than that 5 mph
difference. Gusts and/or wind gradient effects will often account for
more than twice that.

Bob K.
http://www.hpaircraft.com