[Matt Chapman]

Spades. Okay, here we go.
I'll try to keep my thoughts in some sort of order, but I'm sure to bounce around a little bit. As far as RC spades go, it's just going to be my opinion, nothing more, nothing less.

First, control systems in most modern aerobatic planes, both FAA certified, factory built and experimental have push/pull, rods. The exception is the rudder, where the cables are used.

Counter balance Vs. aerodynamic balance;
Not all spaded as created equal. It's just not possable to say that a spade is or is not one or the other. Take the Pitts Special S1-S. The plane was built and designed without spades. As far as I know, they didn't even exist yet. The control pressure on all Pitts aircraft is light and balanced, but always looking for increase in performance. The spade is there ONLY for the purpose of lightnening the aileron pressure at the CONTROL STICK. Move on to the Lazer type monoplane and now you have a spade that is aerodynamicly required as a counter weight. It MUST be on the plane to maintain safety. You also gain the benifits, but it's needed to balance the control to prevent flutter. My CAP ailerons are balanced to 103% to 110% in static.
The spade works in both direction.
they are attached at a hing piont also the pushrod attach piont most of the time. The arms go down, and forward. Not always the same geometry as every design is diff. Take the left aileron....as it goes up, the spade plate leading edge goes down...thus exposing it to the on coming air thus "pushing" it down and helping the aileron go "up". At the other end of this is the right aileron going "down"...in turn it's spade is moving "up" exposing it's bottom side to the on coming air and "pushing" it up. So, they do work together. It's not a one or the other type design. This is how we creat a balance in the system.
Angle of attack, incidence...or what ever you want to call it:
The plate is fixed onto the arm. It's not moveable once bolted on. (except a very cool and inovative design by Leo Loudenslager on his Lazer 200) The spade only moves when the aileron are moved. To trim the spade plate, you first need to know that the plane is trimmed hands off. Then, put the plate on the arms. This is where a it can get complicated. Let's assume a "0" incidents wing. ( the angle that the wing is bolted onto the plane...not changable) The wing passes through the air at some angel of attack...this is changable...with the elevator and airspeed ect...
How do we decide what angle to mount the plate? A few ways... all have their owne feel to them and end result.
Before I go on...look at the one photo of the Citabria with it's spade plate. Level flight, but look close and you can see the leading edge of the plate is raised relitive to the bottom of the wing. the Citabria wing is a flat bottom wing. Most acro mounts have a round wing (symetrical airfoil). If you level the plane based on "0" then put the plate on at zero, you will have some angel of attack of the plate in the air. A wing does not pass through the air at zero....at least not while producing lift. so, in effect the plate will be passing through the air with the leading edges "up" relitive to the oncoming air. This is not necessarily a bad thing or wrong. With a "round wing" the air flowing around it flows in the same basic shape as the airfoil, so this would also lead you to believe that you could mount the plate parallel to the bottom surface of the wing....so air flows over it in a 'zero' effect. This is where you want to start. In this position, you will have a very twitchy stick, no center, no feel at all. Not a good thing. We now start to move the leading edges up or down depending on what we want to accomplish. Please keep in mind as well that some planes have the arms mounted at the front of the plate and others at the back of the plate...so keep in mind that you would have reverse effects fom one type to the other. The closer to center the leading edge the less feel you'll have at the stick, the further from center, the stronger the center. Simple, right? Now throw in the effect of upright and inverted flight while pulling or pushing... As air flows back under/over the wing, you want the ailerons to maintain the same feel, but the air will tend to seperate and will change the angel it hits or passes over the spade. This will lighten or increase the weight of the feel during a pull or push, creating a "digging" of the plate. Almost pulling the stick from your hand. Not good when trying to fly precision. Typically you'll see the leading edegs down just a bit. This will creat the center feel, move out of center with ease and mainatine stability through a push. This however is not cast in stone! everyone has his or her own ideas and pref.
Also, the newer planes, Pitts S2-C, Pitts 12, and Python have been desiged to have all the positive control feels without spades. This was done through use of hing point %, balance and airfoil. No plate = less drag.
It's my opinion that it would be impossable to set up a spade on an RC plane. You just have to have feel feedback to get it to work. We are also working to get a "feel" to the human arm. Our ability to move our arms fast, stop fast or on center is based on aileron weight and feel. The servo will do that based on mechanics every time. (at least a Futaba servo will!! zing!)
Take into account that I'm a pilot....we really need the input of some who may have designed a plane or two...say a Pitts Python maybe....somebody in the Florida area....worked with Curtis Pitts....first name Kevin... Jump in Kevin.
Thats my take guys!
This and a dollar and you get a cup of coffee at Wawa. ( for you west coasters..that our 7-11)
Matt

banged this one out...sorry for ALL the spelling...