Spangenberg hidden aileron linkage improved 

This is a proof of concept variant of "The Spangenberg Aileron Linkage" which enables hidden aileron linkage in RC warbirds and other airplanes.
The normal variant has a simpler linkage (see link in the bottom) but this simple linkage produces a mechanical negative exponential which translates a small servo movement around center into a large movement on the control surface which is usually unwanted.
This modified linkage geometry counters that and even adds a mechanical advantage.
The control surface moves 18° up and 14° down while the servo moves around 50° and 45° respectively.
The white parts are 3D printed and post processed using a cordless drill and in some instances a drill press.
The outline of the parts resembles a wing outline at the inner root of the aileron on a 1/5 scale P-51 Mustang. The instructions call for a 22mm up movement and 17mm down movement with high rates. This translates approximately to the mentioned 18° up and 14° down movement. The bottom mounting plate has indicators for these movements built-in.
The steel rod is 4mm in diameter and just rides in a drilled hole in the control surface and is long enough to stick out of the control surface for this demonstration. With the actual version I intend to use a 4mm surface hardened steel shaft. This will ride in one or two linear bush bearings e.g. LM4UU or LM4LUU which will be glued into the control surface. These are 8mm in diameter so they do require some control surface thickness but the advantage is very low friction and minimal slop.
The rest of the parts may be produced from a mix of steel, aluminium and fiberglass flat sheet or even carbon fiber sheet to obtain a good stiffness in the construction.
I have considered to use some very small ball bearings for some of the movable connections to reduce slop, but these might need a press fit to obtain the low clearances for a slop free installation and these will also add to the size of the installation which is a problem with the limited space so close to the trailing edge of the wing.
I will probably use hardened steel pins for shafts as these have very good tolerances and the holes where these will ride will be drilled and reamed to size.
The Spangenberg Aileron Linkage:
www.rcscalebuilder.com/Tutori...