Holly Hawk (oz14124)

About this Plan

Holly Hawk. Radio control sport model. Shoulder-wing layout.

Quote: "Holly Hawk, by Mike Hollison. A stand-a-mile-away, could-be scale model of the type of plane that was raced during the 1930's. Simple and quick to build, and will really move out with a .19 up front.

Holly Hawk was inspired by the shoulder-winged racing planes of the 1930's, with their zero-visibility cockpits, spoked racing wheels, cowled in-line engines, and bulky fuselages.

The model was intended as a Sunday flier, of simple construction, nippy in the air, but no screaming bomb that the average pilot would have difficulty handling. It can be built with a bolt-down wing for cleaner looks; however, an alternative dowel and rubber band version is shown on the plan for those who prefer this method.

Pilot and windscreen were omitted from the original model; these may be added if desired. Finally, the author's Holly Hawk was flown without the cowl attached; this made for a cooler running engine and made it easy to correct any problems with the power end of the model. The decision to fly cowled or uncowled is, of course, up to the builder.

Wing: Notch the 3/8 x 1/4 trailing edges for the ribs, and epoxy the aileron hinges in place. Slot the trailing edge for the aileron horn bearing, but do not install at this point. Cut the rear wing brace from 1/16 ply and epoxy in position on one of the trailing edge strips. Next, cut sufficient wing ribs from 1/16 and 3/32 sheet balsa, and cement ribs W1 and W3 to the trailing edge. Cement the 1/4 sq leading edge to the ribs, and add the 3/16 sq wing spars, filling in the gap between the spars with 1/16 balsa. This sheeting should be added between the tip rib and rib W1 closest to the center-section; the gap between the spars from W1 to W4 should be filled with 3/16 balsa sheet.

Cut the main wing brace from 1/8 ply, slot for ribs W2 and W3, and epoxy in position. Add the 1/8 balsa gussets atthe tip and leave to dry while you repeat the procedure for the other wing panel.

When both panels are dry, epoxy the two together by means of the ply wing braces, and glue the pieces of ribs W4 in place. A length of 1/16 balsa glued cross-wise between ribs W3 forms the rear wall of the aileron servo box. The wing should now be sheeted with 1/16 balsa as shown on the plan, and the cap strips added, top and bottom. Then, cut two wing tips from 1/4 soft balsa sheet and cement in place; add the 3/16 sq. spars, and cover the tip leading edges with 1/16 balsa. Remove some of the center-section sheeting for the servo, slide the 3/32-inch diameter wire aileron horns into the bearings, and epoxy them into the wings. Add the center-section trailing edge, which is cut from 1-1/4 x 3/8 tapered stock, making sure that the control horns are free to move.

At this point, it will be necessary to decide whether the wing is to be bolted to the fuselage or held on by means of rubber bands. If bolted, the wing must be drilled at the leading edge along the centerline to take the 3/16-inch diameter spruce locating dowel, which should be epoxied in place after the wing has been covered. A strip of 1/16 ply should also be epoxied to the trailing edge as shown, and drilled for the 3/16 x 1-inch nylon wing bolts. When this is done, cut two pieces of 3-inch wide fiberglass tape and gldss over the center-section, top and bottom. (If the wings are to be secured by means of rubber bands, omit the locating dowel and ply strip, but glass the wing as described above.)

Cut out the tape for the aileron servo, and sand the whole wing smooth. All that remains now is to make the ailerons from 1-1/4 x 3/8 tapered stock, slot them for the hinges, and then put them aside, ready to install after covering.

Fuselage: The fuselage is made by cutting two side panels from 3/32 balsa sheet and two doublers from 1/32 ply. Epoxy the doublers to the inside of each fuselage side, and cement the 3/16 sq stringers and spacers in place, as shown on the plan. If the wing is to be secured by rubber bands, drill holes for the 3/16-inch diameter retaining dowels. Cement the 3/8 x 3/36 wing saddles in place and put aside to dry.

Now cut engine bulkhead F1 from 1/8 ply, and drill for motor mount, throttle pushrod, and fuel feed outlets. The motor mount blind nuts should be epoxied in place at this point. Cut the remaining formers F2 to F5, remembering to drill F2 for the wing locating dowel if necessary, and notch formers F2 to F4 for the 3/16 sq top spar..."

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