On Saturday, December 12, 2015 at 3:58:37 PM UTC+3, Martin Gregorie wrote:
On Fri, 11 Dec 2015 17:01:17 -0800, Bruce Hoult wrote:

I don't know about a "shove" on the stick, but before I got rated in it
I practiced flying at 65 knots or so and moving the flap lever fairly
quickly between -7 and landing flap and back repeatedly, while having no
noticeable change in G loading or airspeed.

In that case its a glider-specific issue. If I simply moved the flaps
from zero to landing, my ASW-20 lost 10-15 kts 'like that', but a
simultaneous shove on the stick made the speed loss go away.

Certainly. And gain altitude at the same time.

Increasing flaps gives a bigger coefficient of lift at the same angle of attack. If you want to keep the same AMOUNT of lift, at the same speed, then you have to simultaneously reduce the angle of attack.

But it's not a "shove" .. it's a precise and co-ordinated movement of two controls at the same time. The same as co-ordinating the use of aileron and rudder.

In the case of landing flap, there is also a fair bit of extra drag, so you also have to lower the nose a little to compensate for the drag, as well as lowering it to decrease the angle of attack. Drag is not really a factor in moving between -ve and thermalling flap (at reasonable speed), it's just the CL change in that case.