Feather (oz14964)

About this Plan

Feather. Radio control glider model. Wingspan 42-3/4 in, wing area 263 sq in.

Quote: "Here's a small, lightweight high-performance hand-launch sailplane with a 43-inch wingspan. Construction is simple, flying is exceptional.

As a result of experience, there were several features that I thought would be very desirable in a hand-launch sailplane. Having crashed a lot in the past, I thought a strong crashresistant design would be a good place to start - then things began to fall together.

Strong, to me, meant small. Small meant greater potential launch height. Small meant cheap. I also thought small would have its own special appeal. All of the above have proven true. Let me tel you about crash resistance first.

One of the weakest areas on most radio control HLGs is the wing hold-down screw at the trailing edge. The Zephyr is a good example; drag a wing tip and there go the fuselage sides, However, by anchoring the wing at the leading edge and holding it down at the spar with a screw into a good strong block, well-supported in the fuselage, a trailing edge of the wing will move while the wing absorbs the shock and no damage will result. Many craft have been lost on a downwind turn because of insufficient rudder travel and the inability to pick up that low wing. The Feather has an outrageous rudder with a great deal of travel; like brakes on a car, it is there if you need it. Yes, it will absolutely destroy light thermal flight if used excessively; but adequate control throw is a joy when working in close for a hand catch. Another point to remember: with adequate control throw, good thermal flight could be accomplished on trim alone. The bottom line is: don't bitch about a sensitive airplane - learn to fly it.

As for construction, 1/64 plywood is used extensively in the fuselage. The servos actually serve as bulkheads. Good hard balsa servo rails and the application of 1/64 plywood create a fuselage that is exceptionally strong. Please build it that way. You can even glass the nose with .6-ounce cloth with a minor weight penalty.

The first Feather weighed exactly 7-1/4 ounces ready-to-fly and required no additional weight for balance at the CG. The flight pack weighed just under three ounces with a 100 mA battery pack (no case), Vanguard (Royal) four-channel kit receiver (no case), two World 522 mini servos, and hard wiring (no connectors). With no wind and good lift, the first Feather flew reasonably well, but I soon found that additional weight was required for really good performance-8-1/4 ounces seems ideal and TO ounces maximum for really bad wind.

Don't try to build light - I didn't on the second Feather, and it came out at 8-1/4 ounces with about 1/4 ounce of weight in the nose for balance. Penetration is excellent, and light thermal capability is also excellent (unless flown too slow). if you insist on building light (under 7-1/2 ounces), then I would suggest you reduce the wing span by two bays for slightly under 38 inches.

CONSTRUCTION The construction of this small wonder is, for the most part, fairly standard; and the experienced builder should have little difficulty putting it together. However, there are a few things that you need to know in order to smooth out the process.

GENERAL think it's a good idea to Xerox patterns for the wing ribs, fuselage formers, etc. and then cut out all of the parts so that once you start the actual construction, nothing will slow you down.

FUSELAGE Once the parts are cut out and ready to go, you can begin assembly of the fuselage. My entire plane was constructed with CA glues, and I highly recommend using them, whatever brand you use. Just make sure that when you glue the stiffeners and the 1/64 plywood doublers to the fuselage sides that you make a left and a right side.

After you add the 1/64 ply doublers using slow CA, you can add the 1/4-inch servo rails. Slot the fuselage sides at the rear to allow the control cables to pass through and glue the cable sheathing in place along the fuselage sides. CA the pushrod tubes to the fuselage sides to prevent buckling under load and cross them at the fuselage rear exit points in order to allow for smoothest possible mechanical action, ie prevent kinking.

Before gluing fuselage formers 1 through 5 in place on one of the sides, you should make sure that the formers are wide enough to accommodate your radio receiver, and remember to consider the space taken up by the control cables as they pass all the way through the radio compartment to the servo area forward of the wing. When you are sure that your radio gear will fit the small areas provided, you can join the fuselage sides at the front formers. But, before you do, make certain that all formers are set square and true. When joining the sides, check that the two sides align exactly, and be careful to avoid the dastardly 'banana-shape syndrome' when you join the fuselage at the rear post.

When it is time to sheet the top and bottom of the fuselage with 1/16-inch balsa, notice that the plan calls for the grain to run lengthwise. This is not the common practice, but it seems to add greatly to the strength of the fuselage.."

Direct submission to Outerzone.

Update 4/12/2023: Added further article from RCSD, June 1989, thanks to Pit.

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