Lockheed Electra (oz13338)

About this Plan

Lockheed Electra. Free flight scale twin model, for rubber power, using flexible drives. Scale is 1/16.

Quote: "Opening a New Era in Model Science! An Enclosed Power, Flying Scale Lockheed Electra. Embodying the first successful solution of the power transmission problem for twin engined scale models, this 3/4 inch to the foot reproduction of the World's fastest transport is the trail blazer to a whole new field of Model Building. By Vigilio Sturiale.

Model Aircraft Engineer is proud to present herewith its contribution to the ever advancing science of miniature airplanes. The gearless, pulleyless, angular drive, power transmission used for the first time on this model of the Lockheed Electra, allows almost 100% efficiency for the two rubber band motors. The device described in this article not only allows accurate scale replicas of twin or outboard engined planes, but also allows you to build successful flying scale models of autogiros, one of which we expect to make the feature model for the October issue.

The real Lockheed Electra, with its fifty-five foot wing span is an extremely well designed ship, and for that reason, we have been able to keep the same proportions in our flying scale model of it, with changes in the landing gear and props only. It is rumored that the Electra will be entered in the Australian Race, and the speed of the big ship is easily great enough to allow its competition. The model shown here will be like its prototype, an extremely fast ship.

Notes Before Building: The master model from which these plans were drawn, balanced perfectly upon completion. Before cementing in place, all the large formers were hollowed out with a sharpened pencil ferrule and tubes sharpened at one end. The wing, stabilizer, and rudder ribs were also hollowed out. Medium balsa was used extensively. The author advises the builder to hollow out all of the above mentioned parts.

Fuselage: This fuselage is the usual frame and former type. Two fuselage sides are made exactly alike and coupled together by cross braces. A 1/4 in section of the bottom longeron is cut away to allow the wing spar through. It would be advisable to build a jig for the sides of the frame so that accuracy may be assured.

Cut the various formers from the required stock and cut only the major slots in all the formers (top, bottom and fillet stringer slots) and the remaining slots should be cut from all the formers of sections 1-3-8. Use sandpaper file for all slots. When this is done the formers are cemented in their correct positions. The major stringers are cemented in this slot. The other stringer slots are cut after the formers have been cemented to the fuselage.

NOTE: Small sections of B-3 & S-3 are cemented to the balance of these formers after all stringers are, set in. Bottom stringers are not cemented in until wing has been cemented in place.

The solid nose block is cemented to the front formers. The window outlines are cut to shape from sheet balsa and cemented in place. One part of the front window frame will have to be curved both ways, ie curved from the side and also from the front, so as to follow the contour of the fuselage accurately.

The following instructions will be found helpful in filling in the nose of the model. Take a piece of 1/8 sheet balsa about 3/4 in wide and about 3 ft long. Bend this strip (over a candle flame) around in the shape of a circle. This in turn is cut up into sections about 3 in long. These pieces are then cut slightly larger than the opening they are to fit in, beveled, on all edges, forced in the opening and cemented. This is done to all the openings of the nose and when cement has dried thoroughly, the projections cut off and the surface sanded smoothly.

Wing Construction: The various wing ribs are cut out from the required stock, two of each required. The ribs should be hollowed out for lightness. Holes are made in the ribs through which the flexible shaft passes, and these holes are reenforced by cementing copper washers, full size given in the drawing, to both sides of these holes. Cut all slots for main spar, stringers, sub-spar and leading edge.

The wing spars are of the box type, ie two sides, a bottom piece and a top piece. As the names implies these spars are built like a box, and therefore need no detailed explanation. It would be wise to build a simple jig to hold the ribs in perfect alignment while the cement is drying.

The spar should first be laid over the drawing then the ribs cemented to it. The leading and trailing edges, sub-spars and stringers are also cemented in at this time. The spar is sunk into the ribs and therefore there will be little openings in the ribs after the spar has been cemented in place. These openings should be filled in with rib stock. Cut out landing gear spars and cement them in place.

The ailerons are built independent of the balance of the wing. Diagonal ribs in the ailerons should not be forced in place. The tips and fillets are made as shown, and cemented in place. Leading and trailing edges are sanded to the proper shape. A section of the leading edge is cutaway to allow the flexible shaft to pass through it.

The leading edge covering material is of 1/32 flat stock and is very pliable when doped. Before the dope dries, the stock is bent around the leading edge and pinned in place. When dry, remove it, cut to proper size to fit from the first upper stringer to the first lower stringer, and cement in place. A small hole is cut in this covering through which the flexible shaft passes. This hole is reenforced by cementing a copper washer over it.

The solid portion of the wing tip is cemented in roughly and finished to shape when cement has dried. Iron wire hinges are made as shown and cemented in place on the aileron wing spars. The wing spar joiner is made and cemented to both ends of the wing spar thus uniting the two halves of the wing proper. This wing spar in turn is cemented in place in the fuselage, center to center.

Flexible Shaft: Cut the coil spring into two lengths, 6-1/2 in long. The solid shafts which are to be soldered to this coil are cut to 3 in lengths. These shafts are inserted in the bushings, flatened at one end, at the flatened end hammered back into the bushing, thereby cutting a keyway into the latter. The bushing is filed a. little so as to make its diameter a trifle less than originally, and forced into one end of the coiled spring. Make four such devices. Now with the proper soldering equipment, the bushings and shafts are soldered into the coiled spring.

Bearing Block: The bearing block is built from two-ply laminated stock 3/16 thick, with flanged bushings cemented in place. The flanged bushings are made by soldering a copper or brass washer to a piece of brass tubing..."

Direct submission to Outerzone.

Scanned from the original 1934 magazine pages, at 600 dpi.

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