CO-2 Swatt

CO-2 Swatt

The CO-2 Swatt is an easy-to-build, rugged free-flight model constructed entirely of sheet balsa. It was developed as a small-scale design study of a low-cost, deep-penetration attack aircraft concept — an alternative to very expensive, highly sophisticated military types. The model is well suited to CO-2 power (the author used a Brown Twin CO-2), but most single-cylinder CO-2 engines (except the very smallest) will suffice.

Concept / Background

• Rising costs and maintenance of full-scale military aircraft have led to interest in relatively simple, low-cost aircraft for certain tactical roles.
• The Swatt represents a study of such an aircraft: simple, inexpensive, capable of operating from poor fields, and hardy in operation.
• The pusher configuration protects the engine in impacts and gives the model a distinctive appearance. CO-2 engines operate well in either rotation direction.

Materials and Tools

• Sheet balsa (various thicknesses): center wing panel, outer panels, 1/16" and 1/20" for tail surfaces (or sand 1/16" down to 1/20"), 0.050" sheet (two pieces glued together is an alternative).
• 1/8" hard balsa for tail booms.
• Piano wire (.030–.040") for optional skid "whiskers."
• CO-2 engine (Brown Twin shown, any suitable CO-2 may be used).
• Cyanoacrylate adhesives (CyA) — examples: Hot Stuff, Jet, Zap.
• Sanding block, abrasive paper, flat piece of wood for sanding.
• Glue/cement for balsa assembly.
• Tank and fittings for CO-2 engine.
• Dope with plasticizer or MonoKote for finishing.
• Clay for trim testing.

Construction

Wing

1. Select wood so each wing panel is uniform in weight.
2. Prepare a right-hand and a left-hand outer panel and a center panel.
3. Sand the airfoil into the outer panels carefully; be consistent between left and right.
4. Assemble the outer panels to the center section after shaping the airfoil.
5. Set the dihedral as shown on the plans.

Tail Surfaces

• If 1/20" sheet is unavailable, sand 1/16" sheet down or glue two pieces of 0.050" sheet to achieve the required thickness.
• Sand stabilizer and vertical fins to an approximate airfoil shape; avoid making the leading and trailing edges feather-thin.

Tip: Use a simple sanding jig if available (piano-wire supports or similar) and abrasive paper on a flat block to achieve even thickness and contour.

Tail Booms and Assembly

1. Cut tail booms to shape and sand to the proper cross section.
2. Assemble the wing, tail surfaces, and booms into a single unit once shaped.

Fuselage

1. Cut and/or fabricate fuselage formers.
2. Draw the fuselage outline and recommended former locations on the fuselage sides before cutting; prepare distinct right-hand and left-hand sides.
3. Assemble the sides and formers; ensure all joints are well cemented or glued.

Engine and Tank Installation

1. Install the tank and CO-2 engine in the fuselage.
2. With the engine mounted, perform a bench test run to confirm functionality and to make any necessary adjustments — it’s easier now than after final assembly.
3. Protect the engine from dust during remaining construction.

Final Assembly

1. Slide the wing-tail unit into place and glue securely.
2. Add top fuselage sheeting.
3. Give the whole model a final sanding; remove glue bumps and rough areas with fine-grit sandpaper.

Finishing and Decoration

• Paint camouflage if desired: irregular strips of dark brown and light brown dope on upper surfaces, light gray below.
• Use dope with a plasticizer added to prevent destructive warping.
• Canopy area may be doped white or covered with white or silver MonoKote trim.
• Be sure to place your name, address, and phone number in a conspicuous place on the model.

Flying

1. Before powered flight, test-glide the model over grass.
2. Add clay fore or aft until you obtain a nice, smooth glide.
3. For the first powered flight use a partial CO-2 charge.

• If using a regular prop, it must be reversed on the shaft so the shaft operates in a clockwise direction.

1. Launch with a smooth shove and observe the flight pattern.
2. If flight is erratic, check for warps and remove them by steaming.
3. Adjust engine thrust line with shims of cardboard or wood if needed.
4. After trimming and satisfactory partial-charge flights, proceed to flights on a full CO-2 charge.
5. Flight behavior: model typically climbs out, may maintain altitude and circle for a time depending on temperature and cartridge charge, then begin a slow power descent.

Tips and Notes

• The propeller shown in photos was mounted "backwards" (reduced efficiency) to help keep the model within a small flying field — useful where confinement is needed.
• CO-2 engines can be relatively costly; the pusher layout helps protect the engine in nose-first impacts.
• To enable ground takeoffs from smooth surfaces, add whiskers of .030–.040" piano wire under the front boom section; they act as lightweight skids, nearly as effective as wheels with less weight and drag.
• This is a straightforward sheet-balsa free-flight model that yields satisfying results and a realistic pusher appearance derived from a plausible full-scale concept.

Transcribed from original scans by AI. Minor OCR errors may remain.