Biplane aileron linkage geometry

[Wingin' Wayne]

I'm building a foam biplane. I'm wondering about the linkage at the trailing edge of the top and bottom ailerons. I did a search and found one thread and the only thing it mentioned is to keep it as close to the trailing edge as possible. Is it that simple or is there more to consider? Any advise would be appreciated! Thanks.

[Bill Mixon]

There may be lots of things to consider depending on the design.
If it's a small foam plane then it isn't too critical. Some things to keep in mind..

First of all making the linkage connection at the trailing edge is good from a mechanical standpoint. (any slop in the setup will result in minimal control inaccuracies)
A potential problem with this setup can be excessive weight at the trailing edge, especially with heavy linkages, and/or ailerons with a long chord. This can lead to flutter as well as mechanical issues (inertia of the linkage is working against everything)
So it would be a good idea to keep your linkage as light as possible.

Next would be keeping the linkage connection points directly back from the hinge point. A very important step IMO
Many setups have the connection points on the top surface of the bottom aileron, and the bottom of the top aileron. This will always result in some amount of differential throw.

If this is a small foam plane (12 oz. or less) you might want to use a 1/2" to 3/4" strip of foam on the trailing edge "hinged" in place as with typical tape hinging. Add a piece of foam to the back edge of this to form a "T" shape. this is one of the lightest and simplest methods for small biplane aileron connection.

[eflightray]

Wayne

Just in case you want any more info on foam biplanes, have you done a search in the Foamies (Scratchbuilt) forum (http://www.rcgroups.com/foamies-scratchbuilt-428/) on biplane? as there are quite a few threads.

If you don't know some of the search tricks -

Go the the Foamies (Scratchbuilt) forum.
Click on 'Search this Forum', (not the 'Search' one).
Click on 'Advanced Search' at the bottom of the drop down, just below the search box.
In the new window -
Enter 'biplane' in the Key Word box.
Just underneath it, set that box to 'Search Titles Only', (the alternative is to Search Entire Posts and that brings up too many hits).
Click on 'Search Now'.

I had it come up with 31 threads with biplane in their titles.