Hmmm....dunno about an airplane keeping the same airspeed with flap deployment, unless it's related to the amount of flaps deployed.

Real world experience: Used to fly a Cessna 150. Would set up for hands-off level flight speed of 80 MPH on downwind leg. When abeam of the landing point, it would be carb heat on, throttle to idle, and then hit the flap switch to lower flaps until they were fully-deployed. You used the controls to basically hold the nose level as the airplane slowed as the flaps came down. As soon as the flaps were fully-deployed, you turned base leg. The elevator was not re-trimmed, and the airplane wound up being trimmed for a hands-off 65 MPH. Stay power off until landing, with only a few blips of throttle to 'clear' the engine. I believe the pattern altitude was 800 feet AGL.

If power was added, the airplane would tend to hold the 65 MPH. The elevator had to be re-trimmed for the airplane to want to hold a different speed. This showed that while the trim setting did not actually change, the relationship of the elevator trim setting and the flap deployment made for an effective change in the actual trim of the aircraft. It would not hold the original trim airspeed when the flaps were deployed.

Same thing for flap retraction. You could be in a climb after takeoff, trimmed for constant airspeed. Slowly retract the flaps, and the airspeed would increase as they came in. Didn't change the trim, but the speed would increase...again, it's because of the complex relationship between the effective angle of attack change, the effective decalage between the wing and the tail, and the change in drag caused by the flaps.

Make no mistake, they all change when the flaps change, and it's not a simple relationship...and models will basically behave no differently than full-size aircraft.