If a person is building from plans or kit it's much easier to set the incidence. With ARFs it's not.

The proper way to set up a plane is to first find the datum line. This is a line that runs down the side of an airplane from firewall to the tail. It may or may not align with the prop shaft. Depending on the design of the aircraft, this line will be above or below the thrust line of the engine. This line is the center of influence for the design. This is also the "plane flying level" line determined by the designer.

A true 0-0 aircraft has the engine prop shaft, wing and stab on this line. Move the wing below this line and the line now becomes the thrust line and the datum line moves down. Move the wing above the line and the line moves up. This line is only important to the designer. For our purposes, all we care about is finding a straight line on the aircraft that is parallel to this line. In many older designs such as the Taurus or a Kaos the top of the fuselage is a good representation of this line. On some newer planes such as Cranks Focus Sport, the canopy hatch opening on top of the fuselage is parallel with the datum line.

Once a datum line or parallel line has been determined all incidences will be set from that line. In modern pattern planes with adjustable wing incidence, the wing is set to +.3 degrees. That is, the leading edge of the wing is set .3 degrees higher than the trailing edge. After the wing is set, the common thought is to set the Stab at least -.5 degrees to the wing. This will be -.2 degrees to the datum (leading edge lower than the trailing edge). I usually try to set the stab -.6 degrees to the wing to cancel out the .3 degrees in the wing. This keeps the datum line "flying level". Due to the negative in the stab the engine must have a negative incidence to conteract the desire of the tail to fly low or drop. Why the engine needs -1 degree when the tail is only .3 is beyond me but experience shows that this is a good starting point.

These settings are only starting points. One cannot determine any variations or changes without flying the plane. The last seven planes I've built have all been set up the same way (including the Intruders) and needed only minor changes. Usually changes where to the engine incidence and CG. The one Intruder still flying has these settings and of all the Intruders I've flown (4 so far) it's the best flying Intruder. Sorry Crank, Mike's flies better than yours.

Later

Bob