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Chuck's Cardboard Model Aircraft

The following tools are recommended for cardboard building:
  • A metal yardstick for layouts & for a hard cutting & scoring edge.
  • A utility knife and x-acto knife for cutting out  big & small parts.
  • A screening tool for scoring the cardboard fold lines.
  • A 1" wide roll of white gummed water activated paper tape.

The gummed paper tape is the same used by the butcher at your local grocery store to wrap up meat, so check with them to see if they might sell you a roll.  The tape can be ordered from FriscoSpices, 10905 Harrison St. LaVista, Nebraska  68128   Phone:  402-339-0550.  Ask for the current price for the "White Gummed Tape, Water Activated".  It's 1 inch wide by 500 feet long.  That's a lot of tape, but you can share it with your fellow modelers .   


Construction Tips

Material:  The basic building material is 1/8" B flute corrugated cardboard (CB) with a white paper finish on one side and a brown unfinished paper on the other side.  The white paper finish side, which becomes the outside  surface of the model, results in a smooth surface for final finishing.  CB with brown facing paper on both sides can be used, but the finish will not be as smooth and it may take extra coats to give good coverage with light colored paint.  200 lb test board (a measure of its strength) is the most readily available material as it is commonly used for CB boxes.  150 lb test board is perfect as it is lighter in weight than the 200 lb test board, but with adequate strength for model building.  But it is harder to find as this board usually requires a special order.

My main motivation for using CB was to reduce building time and cost, with the emphasis on cost.  Its my hope that you can obtain CB for free.  So check local merchants and their dumpsters to see if you can find some free CB.  But a word of caution here!  The biggest mistake first time CB model builders make is to use two plys of 1/8" CB or 1/4" CB which they think is required for added strength.  DON'T DO IT!  These designs have been tested and are plenty strong.  The added CB is not needed and will only result in an overweight model with poor flying characteristics.

If you can't find what you want for free, then look to buy some good quality CB in your area because it is inexpensive if obtained locally.  The best way to do this is with a computer search on "Boxes Corrugated and Fiber".  Hopefully, among the results will be a few companies in your area that manufacture corrugated boxes.  A phone call will tell you if they have the 1/8" B flute with the white paper finish on one side. 

Glue:  Water based glue, such as Elmers or Titebond, is recommended.  Contact cement is not recommended since parts cannot be shifted when gluing surfaces.

Folding:  The scoring of the fold lines is done with a screening tool available at hardware stores.  It consists of a handle with a 1-1/2" radius wheel at one end, which is run along the metal straight edge on the fold line.

Waterproofing:  Waterproofing, if desired,  can be applied to the raw CB material before you cut out the parts.  Mix 25% clear polyurathane with 75% paint thinner and brush on the white outside of the CB sheets and allow 48 hours to dry.   I don't waterproof my models as I don't fly in rainy weather.

Finishing:  One advantage of CB is that it gives a solid surface with no open areas to cover (See the completed Moth Minor model below).  My finish method is to give 2 coats of clear dope, sanding lightly between coats with #400 sandpaper, followed by 2 coats of color dope.  Coverings, such as Solarfilm or Monokote, can be used.  But with these, it is recommended that the surface not be doped, which will result in a better bond.

Paper Tape:  All seams, joints and exposed edges of he model are covered with strips of gummed paper tape.  Cut a thin strip to length, dip in water and smooth it over the seam.  Use paper towels to blot up the excess water on the tape.

Construction Photos

For wings with curved upper surfaces, each wing panel is built from a single piece of cardboard (CB), flat on the bottom, then scored and folded on the leading edge to obtain a curved upper surface.   The wing  single spar is made of balsa wood capped with 1/4" sq. spruce.  All ribs are CB.  A 1/8" plywood gear mount is inserted in the bottom wing panel.  The Moth Minor wing has a flat center section and outboard sections with dihedral.
The fuselage sides are lined with balsa strips recessed 1/8" from the CB edge.  CB supports for the 1/8" plywood bellcrank and fuel tank supports are added to the fuselage sides.  
Flat CB pieces complete the basic box section.  CB bulkheads and a single balsa stringer are then added to the top section.   CB is removed where possible to save weight.
The main landing gear struts mount to the plywood plates in the bottom wing with 3 nylon gear clips.
Completed model ready for painting.
Wing Shapes
The photo at the right shows the 2 methods I use in wing building.  The wing with the curved upper surface is scored every 1/2" on the upper surface from the leading edge back to the spar.  The CB surface then easily wraps around the CB ribs giving a smooth contour.
The biplane wing uses a simple wedge shaped wing section with a single spruce spar at the profile high point.  No wing ribs are required, making these biplane wings extremely easy & fast to build.
The empennage components are 2 pieces of CB laminated together crossgrain for strength.  The LE's are capped with 1/4"x1/8" balsa and rounded off.  I use a 1/4" dowel elevator joiner and either cloth hinges or the nylon flex hinges.

The fuselage sides are joined at the firewall and the tank and bellcrank have been installed.  I attach the fuel tank with multiple rubber bands.  The pushrod is  1/4" square spruce with wire on each end attached with nylon thread and glue.
Scored CB fuselage top decking pieces are glued over the bulkheads and centerline stringer.  Gummed paper tape covers the seams just forward and aft of the cockpit.
The cowl is first laminated  from balsa and then carved to shape.   
Finished with dope and Monokote details.