I have about 35 degrees deflection on the flaps. The air sirens are called air whistles from, I-4C.com. They are really whistles that U cut to different lenghts ( u get 2 of em) to produce a different tone between the two. I have mine mounted on the belly pan,& when I put it in a dive ,U can hear them just over the sound of the engine.It always draws a lot of attention at the field.I`ve had my Stuka since 2003,broke the right wing off twice! It will tip stall if U bring it in too slow,Just be a couple clicks above idle when landing, & u will be fine..,Also ,if U retract the flaps as soon as U touch down,it will help keep the plane from bouncing.