OK, Matt. I'll chime in on this one.
Why spades? Early ailerons such as on cubs, Pitts S1S, Buckers, etc. are Freise style. These had light forces. Rol performance was increased by sealing the leading edge of the aileron to the wing trailing edge. Later, ailerons changed to symetrical style that are round nosed with the hinge line in the center of the radius of the nose. This allowed easier sealing of the aielrons to wing gap but with very high stick pressures. This is the S1T Pitts style aileron and eal monoplane ailerons. From what I can recall, the Zlin monoplanes of the late 60's or early 70's had spades first. When the S1T wing and new aileron came to be too heavy, the idea from the Zlin was used and the forces were reduced. Rumor has it that this idea came during a discussion between the manager of the pitts factory at the time and a friend of our from Texas. It worked.
As it has been pointed out, spades are tuned to the airplane and pilot. Each unique. Yes, the mass of the spade being forward of the hinge line can be used as some portion of the required mass balance of the aileron system. If it is as on the SP95 and a few other designs, do not fly with spades off or the ailerons will flutter and flutter is bad...
Spades can be thought of as additional aileron area. This added area is forward of the hinge line of the aileron and forward area can be used to lessen the stick forces for the pilot. In the 20's the Travelair 2000 had 'elephant ear" ailerons which had a rounded forward section at the tip that resembled that of the mammal's ear. This area reduced stck forces.
Note how the spades on the extra are mounted on a slope relative to the wing, lower inboard. This allows these spades to do 2 jobs. One, lighten the roll stick forces and two, allow the extra to comply with FAA certification of having to be able to lift a wing with the rudder (no dihedral in the wing so needs this). The tilted spade catches the air in yaw and deflects the ailerons to allow rudder/roll coupling.
It is possible to build ailerons that do not require spades. It takes many tries to get it right. Even at that, it is only right for one person on one airplane. We did get it right on the python. The ailerons are much larger than the model 12 that we kit yet hae no spades. There are many other factors that played into getting a spade free set up. Hinge point is only one. Simply changing an aileron from 2 hinges to 3 can change the aerodynamic stick forces.
The idea of using spades on a model would be tricky to sort out. It is very easy to have spades that are too large and over drive the controls. In this case, you could actualy end up with tension loads on the linkage instead of compression loads. It would be possible to have the ailerons stick at full deflection. Setting the pitch angle on the spade is critical and if it is off from optimum, the ailerons may have zero centering or get snatchy in some flight attitudes.
So, to be more direct to the original poster's questions of are model spades available? I don't think so. Should they be? Nah,....most likely not for the many reasons pointed out in this thread. Knocking them off in wing bags, in the grass, etc., would be a real problem.
Kevin Kimball
www.pittspython.com