Postby Cary Bailey » March 9th, 2018, 10:48 am
Arthur, most under fuselage wing configurations that have flaps have a tendency to drop the nose slightly when flaps are employed. This differs from one type to another. I fly a P51, which when flaps are deployed drops the nose by 10 degrees. On landing the full size you have to keep the airspeed right on the money so that at touchdown the nose it at the correct attitude (level and not pitched down, which you can monitor accurately) and at that airspeed is such that the tail naturally wants to slowly sit down, if you watch closely most full size P51 pilots raise the flaps under a certain speed after landing. With a model it is harder to judge that airspeed at landing, however what I do is when the wheels actually touch down I retract the flaps either partially or fully which avoids the nose down attitude, stops the nose from wanting to bury itself, avoids you wanting to feed in more elevator to lift the nose which causes you to overcompensate, the wing becomes into a flying attitude but the lack of airspeed causes it to stall. Raising the flaps in this way allows the tail back into it's normal attitude, stops you from applying unnecessary elevator, allows the tail to fall to it's normal position and then as the airspeed falls away the tail lowers down.
So I hope I have explained that so that you can watch what your Spitfire does as you apply the flaps. Try it during your test flight, at a height that is safe & that you can see the effect of the flaps on the nose attitude so you can then judge what you need to do. I do know some guys "mix" in a slight amount of up elevator when flaps are deployed, my advice is don't adopt that idea as it is a false economy especially if you get your airspeed to low, the elevator is still biting to lift the nose, the nose rises, causing the wing attitude to rise and you get an instant wing tip stall & a possible broken wing!
Cary