I assume you are talking about the wing-mounted fairings on the C-model Sierras, that are fore and aft of the retracted main gear wheels. Beech hasn't had them for years, and no one else is making them. They are available only as salvage items.

It is also quite easy to make a foam form for fairings like this, then attach it to a backing plate with the correct curvature for the wing surface. Release compound is applied and a thin but strong layup made, using a light (thin) grade of unidirectional glass cloth (available at a good hobby shop),and a resin such as Vinylester (not Polyester auto resin). The thin lightweight cloth, when cut and laid "on the bias" (meaning the cloth weave is diagonal to the part's centerline), is very easy to work around curves. The mounting flange is formed by flaring out the cloth at the bottom of the form. The flange edge is left ragged until it cures, then is trimmed with scissors to width.

You can use the blue Superfil material from Aircraft Spruce to fine-finish the form, as well as to final-fill the outside of the fairing prior to priming. Keep in mind that the fit should be as close as possible to the tire. The front of the leading fairing should be curved to resemble the leading edge. The Beech leading fairing does not have the ideal front shape; it is too blunt. The aft fairing should be tapered aft as far as is practical. The Beech main gear aft fairing is actually only about 2/3s as long as it should be, and is too abrupt where the flange is formed on the trailing edge. It is also unduly "draggy" by virtue of the stiffening channels molded into the ABS plastic, generally unneeded in a fiberglass design. A glass design can easily be stiffened, if needed, by glassing a piece or two of very light balsa wood onto the inside surface.

The overlapped fairings that were made for the flap brackets, during the experimentation by the Sierra engineering group, went almost to the trailing edge of the wing. An experimental aft fairing that I made for the retracted nose gear wound up a tad too wide for the wheel, and wasn't long enough. I was unable to tell any effect at all during its testing (meaning back to the drawing board).

Your friend would be better off to make his own, and to use an internal flange having small access holes for a screwdriver. It can then be custom-designed and fitted for best looks and function. Those holes can be filled with removable sealant, if the fairing has to come off, and the concealed fasteners will look smoother and have less drag. The perimeter of the fairing can then be neatly and tightly caulked. The internal flange can be made by wrapping the cloth around the bottom of the mold, rather than flaring it out over a molding mount plate. He is probably already aware, but in lay-ups the strength is in the glass; the resin just holds it in position. Excess resin is just wasted weight. Sort of like concrete-reinforced steel construction; all the strength is in the steel bars; the concrete just keeps them from bending. Excess concrete beyond the design just adds weight and cost, with no added strength.


>I have a friend that wants to buy a set of wheel fairings as on the C24Rs. They are to be used on an experimental >retract. Any body out there have some or know of a good source? Paul<
_______________________________________________
BAC-Mail mailing list
BAC-Mail@beechaeroclub.org
http://www.beechaeroclub.org/mailman/listinfo/bac-mail