Forty-Niner (oz5026)


Forty-Niner - plan thumbnail image

About this Plan

Forty Niner. Control line sport model, for K&B Infant power. CL model by Bill Winter. Here's a small control line plan from the April, 1949 Model Airplane News.

Quote: "A vest pocket controliner that seems ideal for beginners - bet oldtimers will fall for it too! Forty-Niner, by Bill Winter.

BECAUSE it has only .020 cu in displacement, the new K&B Infant engine makes possible a whole new field of model designs, one of which is the sport controliner, the semi-scale little brother of the 'junior Goodyear' designs now being flown all over the country in bigger classes. Designed on the Goodyear racer motif, our Forty-Niner has a number of interesting features.

First, it is a square design, having one foot wingspan and an overall length that matches. Made up entirely of sheet balsa, it is quite light in weight. With paint and engine the top weight should be approximately 2 oz; it will be several tenths of an ounce less if you forego the colored dopes. With 18 ft .014 dia lines, the Forty-Niner has done 30 mph indoors. We strongly recommend using .008 lines for maximum performance.

Perhaps it would be interesting to know the origin of this airplane. When the Infant first appeared it was our thought that this engine should make it possible for the be-ginner to fly controline without any of the usual fuss or feathers. Why not build a trainer? The soundness of this idea was noted in the performance of the Forty-Niner indoors during the winter. Two beginner modelers who had never flown controline were briefed by Walt Schroder (who tossed the ship together) and both beginners managed the Forty-Niner successfully from the start, even though the ship had to pass over rows of folding chairs in the confined flying area.

Another good feature is the wide latitude the design leaves you for playing around with your own profiles. Note that the fuselage is built upon a balsa tube; the profile is cut from sheet and glued to the top of the tube. So you can alter this detail as you will, making any manner of Goodyear racer that comes to mind. Even a Vee-tail should make little difference.

CONSTRUCTION. The main part of the fuselage is the sheet-balsa boom which is formed from 1/16 thick stock. Select wood that offers little resistance to bending, and be-ware of wood that splits the instant you begin to curve it. It will be necessary to butt the joints of two pieces of sheet since 3 wide wood will not go all the way around the tube. Your best bet is to find some round object, a curtain pole, mop handle, etc. that provides approximately the diameter of the tube, then wet the sheet and form it around the tube. The wood can be held in position while drying by wrapping strips of cloth around the work. The plan clearly shows how the fuselage is built, the 1/8 sheet formers, the plug of balsa that fits into the tail, how the wing goes through, how the tail attaches.

For the fellows without a lathe, there is a simple way to make the tail plug. Remove the head from a No. 9 wood screw; use pliers to turn this wood screw into the rear center of the plug. Employ a knife to rough shape plug and then insert screw into chuck of your hand drill - have rear face of the plug flush with the jaws of the chuck when jaws are tightened over the screw. Clamp your hand drill in a vise, leaving hand wheel free for use. Rotate hand wheel rapidly while holding coarse sandpaper against the plug - continue until the plug assumes proper shape.

The profile superstructure is cut out then covered with thin celluloid. Two number 2-56 x 1/4 in RH machine screws fasten into two nuts glued to the rear of the 1/32 plywood firewall; this is detailed on the fuselage drawing. The landing gear is bent as shown from .030 wire, then glued to the bottom of the fuselage tube as seen on side view. The wheels on the original model were good looking but heavy, so it would be a good idea for the sake of flying to forego ap-pearance. Use thin and light, but strong wheels.

The stabilizer and elevators are cut out from firm 1/16 thick sheet balsa. The size and location of the control pivot is shown on the side view, as is the bellcrank and pushrod, mounted externally under the wing.

The wing is cut to shape from soft 1/8 balsa. Sand the wood to an airfoil shape, rounded somewhat at the nose or leading edge and slightly pointed at the rear or trailing edge..."

Update 11/01/2019: Added article, thanks to RFJ.

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