The Andes Bipe stabs are of “built-up” laser cut balsa and ply construction. The workmanship quality looks excellent. The first task was to go over the film with a covering iron to remove any wrinkles and go over the edges.
Next job was mounting the elevator servos. In this case, my Customer provided a pair of Futaba BLS173 servos. The first thing you’ll note is that the servos are mounted well down inside the stab half. This necessitated an extension being added to my pin vice. See gallery.
The installed servo Tray seems to be cut and drilled to suit the Futaba BLS153 Servo which is bigger than the BLS173. This being the case, the existing servo screw holes were plugged with toothpicks and hit with CA. A new servo plate to suit the BLS173 was then drawn up and cut on the CNC router. The new plate was positioned in the stab and then glued with CA. Perfect. Well, almost... Because the Servo it mounted so far into the stab a full length servo lead is needed. As you can see from the pictures, these servos had shortened leads. Never mind, new leads were soldered into both servos bringing them back to standard length. The Radio South hinges are 1” wide which is overkill for F3A. Each hinge was cut in half with a small guillotine.
With the servos mounted, the next item of business is the elevator hinging. No hinges are provided in the kit which gives the builder some scope for using their preferred hinging method. For this build, Radio South CA hinges will be employed. Note: The stab tube socket is quite close to the stab trailing edge. It will mean only a 3-4mm gluing surface on each hinge. For this reason two hinges were positioned at the elevator root.
The position of each hinge was marked on the stab and elevator with a permanent marker. Then each hinge slot was cut using a Tettra Hinge guide and a sharp scalpel. With the slots all cut, one half of the hinge can be glued into to stab or elevator. It doesn’t matter which is glued. Thin CA is the glue of choice and just one drop on each side (top and bottom) is all that’s needed. The CA will wick into the surface. Once all hinges are glued top and bottom, I then hit it with some kicker to prevent any blooming on the film.
We’re now ready to start on the linkages. The elevator control horns are included in the kit. These horns are used on all control surfaces. Ply mounting plates are factory installed in each control surface for the horns. The builder needs to only drill the two holes for the countersunk wood screws.
For this build we’ll be using MKS 6mm Hubs combined with carbon fibre servo arms. The Advantage of these hubs is that you have six positions on the spline to optimise the linkage geometry. Speaking of the linkage, the actual link will be 2.5mm Titanium used in conjunction with 2.5mm ball ends. The links are attached with M2 x 10mm stainless screws and M2 locknuts.
When you’re happy with how everything fits and works, CA the other half of the elevator hinges with thin CA.
This more or less completes the stabs. The only task outstanding is drilling the stab tube retention screw holes and attaching the stabs to the fuse. The weights came out at a respectable 111 grams and 114 grams with servo and linkage.