Ray's WF-XL Building Tips!

WF-XL Wing Dihedral for Electric Motor powered version


This version of the WF-XL is best suited for electric motor, light footed winch and Hi-Start launching.

Electric motors installed in RC Sailplanes has swept the world of Woody builders. The attached electric motor offers a high degree of convenience and ease to launching and finding a flying field suitable for flying safely.

The straight wing rod is 1/4" diameter. The wing dihedral is set by 2" under each Rib # 12. See Wing Construction Tips on my Sky Bench web site for tips on how to install the brass tubes and rod.

The plan is drawn showing flaps and ailerons, but materials are not furnished. See Frank Wren's on line WF-XL instructions with great photos for flap construction. CLICK HERE FOR FRANK'S INSTRUCTIONS AND PHOTOS.

Due to the wing's in board panel length, the flaps can be used as flaperons, just like the Challengers wings. Flaps can prevent electric motor and prop landing damage and provide a wider envelope of flying

The WF-XL builds light weight, perfect for e-power.


This kit has 1/64th plywood fuse doublers for front and rear fuse sides. Following are some ideas to consider:

Lightening holes in the rear fuse side ply doublers to reduce weight.
Lightening holes in the front fuse side ply doublers aft of the CG.

I use "Testors Cement for Wood Models" to glue the 1/64th ply to the Balsa Wood fuse sides because it does not cause the ply/balsa to curl.

Water based Titebond wood glue can cause curling, but not a major problem. Testors is lighter weight than CA.


The kit has plywood horizontal grain webs to be used where the wing spars are spliced. Cut the straight wing spar webs from the optional Polyhedral joint plywood webs. If you build the wing with poly, use the poly joint parts as a guide to setting the tip angle. I use Titebond on the spar webs.

The two plywood disc are glued to the inside of the 1/64" plywood Fin Doublers to reinforce the stab pivot tube glue joint. Use Fast Cure cure epoxy on the sides of the tubes. Long cure Epoxy is brittle and can break lose, the slow cure is a bit pliable and can take shock without breaking.


The wing rib package includes two balsa wing root caps and 1/16" ply caps. The 2nd set of ply caps are in the fuse package and can be glued to the to the exterior fuse sides. The balsa root caps can be shaped to make a perfect fit where the wing meets the fuse side. I recommend using the eye screws installed in the wing root with a rubber band thru the fuse to hold the wings to the fuse.

The stab package has two balsa pieces to be glued to the fin sides as shoulders for the stab junction. These are necessary to have a long enough stab pivot tube in the fin. Long enough meaning, a pivot tube that doesn't allow the stab to wobble. Use the ply stab root caps as a cutting and sanding guide to shape the shoulders to match the stab's profile. The two plywood disc are glued to the insides of the fin plywood doubler to support the stab pivot tube

The stab package has two balsa pieces to be glued to the fin sides as Wing Rod Brass tubes in wings should be capped before filling in the area with epoxy to eliminate flow of epoxy from enter the tubes.

The stab package has two balsa pieces to be glued to the fin sides as The Wing alignment tubes and Stab joiner tubes are pinched at the ends to retain the wires. Use Micro Balloons glued with CA to secure the alignment tubes.


Sky Bench Aerotech 

Ft. Wayne, Indiana 46804