Wing Ding (oz14175)

About this Plan

Wing Ding. Radio control sport model. Wingspan 36 in, wing area 315 sq in, for 280 electric motor.

Quote: "This article describes the design and construction of a small, geared 280, electric-powered RC flying wing. Powered by three, 800 lithium-manganese (LiMn) cells (not Ni-Cds), flight times can exceed 30 minutes. The low-drag design is fairly fast and quite stable. The Wing Ding will easily handle 10mph breezes, and 18 watts is more than enough power for inverted flight and inside and outside loops.

I must admit that this design was strongly influenced by Tom Hunt's Elipstik, although my Wing Ding is smaller, lighter and has a higher-aspect ratio. I've built three versions of the Wing Ding, and all use the same planform and motor system. The first used seven, 550 NiMH cells and weighed 9.5 ounces. The second - the subject of this article - was more lightly constructed and uses three, 800 LiMn cells and weighs 7.97 ounces; performance is significantly better. The third version is identical to the second, except it has a symmetrical airfoil that improves aerobatic performance.

The Tadiran 800 LiMn cells, 280 Titanic Airlines 3:1 geared system and prop are an excellent combination and provide very aerobatic performance at an average current draw of about 2 amps (about 18 watts of power).

What advantages do LiMn cells offer over traditional Ni-Cds? In two words: energy density. LiMns have an energy density four times that of Ni-Cds; this means that equivalent-capacity LiMn packs weigh 1/4 that of Ni-Cds. Each LiMn cell is 3 volts (not 1.2 volts, as are Ni-Cd cells), and that's why the Wing Ding uses a 3-cell pack (2.05 ounces). Nor do LiMns lose charge as quickly as Ni-Cds. You can charge them and then fly three weeks later without any noticeable loss of power. On the negative side, LiMns should be limited to current draws of less than 3 amps, must be charged at very low rates and require a special charger. LiMn cells must also be handled with care because they are not as robust as Ni-Cds (follow all instructions carefully).

Construction: Use medium-density (8 to 10 pounds per cubic foot) balsa for the long sticks and low-density (6 to 8 pounds per cubic foot) balsa for everything else. As for glue, I mostly use aliphatic resin (Elmer's Carpenters Glue). Sanding is done with 100-, 220- and 400-grit on blocks. For covering, I use Oracover Lite (translucent colors only). Note that I use some balsa faced with 1/64-inch-thick plywood for highly stressed parts.

To glue in the motor, receiver and servos and to attach the fiberglass cowl and belly pan to the finished wing, I use silicone rubber. Glue joints such as these provide sufficient strength and are easily separated with dental floss if later maintenance or repair work is required.

To build a light model, you must make every piece as light as possible. Small weight savings on each piece add up to significant total weight reductions, and the performance differences between a light and heavy airplane can be quite impressive.

Study the plans carefully; I've added a lot of details for those of you who won't read the rest of this article. Tape plans onto your flat pin board and cover with wax paper or plastic wrap.

Tail feathers: The leading edge (LE) of the fin is made of two 1/16x1/8-inch balsa sheets laminated with aliphatic resin. Soak the strips in hot water for half an hour, wipe off excess water and apply a very thin coat of glue to one surface. Block and pin to shape, let dry for 12 hours and sand LE to shape. Assemble fin frame, leaving some extra length on the trailing edge (TE) and bottom longeron for later fitting to the wing assembly. Let dry for 4 hours. Round LE and taper TE, finish-sand, and cover. The finished fin frame should weigh about 1.7g (2.7g when covered).

The TEs of the elevons are 3/32-inch-square balsa curved to shape using a 350-degree F covering iron. Clamp the iron upside-down in your vise so you can hold the stick with both hands. Slide the balsa back and forth over the hot shoe for uniform heating while bending the stick a bit at a time. With practice (and after a few broken sticks), you will find this method is easier than soaking or steaming. Use the same method for curving the top rib strips. Assemble elevon frames, let dry for 4 hours, finish-sand, and cover. The finished elevon frames should weigh about 1.6g each (2.7g when covered).

Later, after the wing has been finished and covered, the elevons are mounted with 1/2x16.63-inch strips of Mylar tape (3M Scotch-brand 850). Be sure to leave a 3/32-inch gap between the wing TE and the elevon LEs. The control horns are 0.036-inch-thick fiberglass CA'd into slots, and they are added after the wing and elevons have been taped together.

Wing: LE and spars are 8- to 10-pound-per-cubic-foot balsa. The LE is laminated from three, 36-inch-long, 1/16 x 1/4-inch balsa strips. You don't need to soak the strips; just coat both surfaces of the middle strip with a thin layer of aliphatic resin, wipe off the excess, block and pin to shape. Let it dry for 12 hours, then rough-sand it (finish-sanding and shape it after assembly).

The main spar is laminated from two, 36-inch-long, 1/20-inch strips that taper from 3/4 inch at center to 3/16 inch at the tips. Trim to length during assembly. The rear spar is a 1/16x36-inch strip that tapers from .70 inch at center to 3/16 at tips. Steam in the curvature in the center and trim to length during assembly..."

Update 7/11/2022: Added article, thanks to theshadow.

Supplementary file notes

Article.

Corrections?

Did we get something wrong with these details about this plan (especially the datafile)? That happens sometimes. You can help us fix it.
Add a correction