This article is a tutorial on the process of adding a covering to a model airplane. You might do this to repair your plane from a crash, to customize it or to give new life to an old model. For instructions on preparing for this project, please see the article Preparing to Put a New Covering on a Model Airplane. It contains information on:
- Project tools and supplies
- Removing the old covering and preparing the surface
- Creating a covering plan and selecting the appropriate covering material
- Making a cutting plan
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First, make cardstock patterns for the curves and transfer these curves to 1/16 sheet balsa. A tip shim pattern is made to fit 1/16 under size at both the top and bottom edges. Cut out of balsa and then glue in place. The 1/16 square balsa strips are added at the leading edge to catch the balsa curved piece. With these in place, you now have something to anchor the curved sheet balsa pieces. Once the pieces are glued in place, fill any imperfections and lightly sand.
Try to employ a V-pattern for attaching the covering whenever you can (see photo above). Begin by tacking the inside center seam and then stretching the film tightly to each side of the center. Then form a symmetrical V out to the tip. Once the V is formed, begin at the center of each side and tack at about 1-inch intervals out to four corners. Once it is tacked, seal it down to the wood.
Cut notches for the film around each rib and seal it down to the spar, then seal it to the trailing edge as well as the center and tip of the wing panel. Seal all edges again and then shrink with heat gun. A good tip is to employ a tactic of sealing down more edge than you know will eventually remain on the model to assist in keeping the film attached while you heat-shrink it. Make it routine practice to reseal film after shrinking with a heat gun as the gun can loosen the adhesive. When all this is done, trim the panel.
Using a Heat Gun
Shrinking film with a heat gun is more art than science. Generally, try to work the entire piece at one time, starting 3 – 4 inches above it. When using a heat gun, remember that you can always get closer and bring more heat into contact with the film. If you are using a covering iron, remember that you can always turn up the temperature. If you get too close with a heat gun, you can easily burn a hole in the film and that usually means you will recover that panel.
Keeping the heat gun or covering iron continually moving across the film will help avoid burn holes. Covering neighboring film with cardboard or a wet rag is a great tactic to avoid burning film. Once the film is taut, rub down any area on sheet balsa with a cotton ball to work air bubbles out and help set the glue. For small creases that don’t pull out with the heat gun, you may wish to remove them with a trim iron rather than risk getting too close with a heat gun. Reseal all seams after shrinking with a heat gun.
The tips are covered in opaque white. If you are doing a one-color covering job, cover the tips first so that the wing film will overlap them. On the Tiger 400, start with the bottom of the tip and then cover the top. Tack the film on the high point or spar position of the top of the end rib and then stretch and seal down that rib to the trailing edge. Repeat this for the leading edge. Then, beginning at the same spar location, stretch the film down and seal it to the outer edges of the tip. When done, carefully shrink it and trim off the excess. Repeat this for the top of the tip, making sure to overlap the bottom, and you have one tip done. Tips take time but the reward is worth it.
If possible, cover all of one color (such as yellow) and then clean the covering and trim irons before switching to a second color. Irons pick up color from the film. Cleaning irons between colors helps avoid yellow or red smears across your snowy white film. Use Ironex to clean the irons when they are cold. Remember to avoid fumes.
Covering the Fuselage
It is time to cover the fuselage. Before covering the fuselage, paint the engine compartment using a paint color that matches the film near it. Use a fuel-proof spray paint, dope or polyester resin if the model is fuel powered. The Tiger 400 is an electric and was sprayed with non-fuel-proof white spray paint.
On a two-color scheme like the Tiger 400, plan ahead on the fuselage so that you cover dark over light, opaque over transparent, from bottom to top, and back to front. On the Tiger 400, the opaque white is on the nose with a stripe running down to the tail. The remainder of the fuselage will be transparent yellow with some red trim.
The bottom front and rear of the fuselage are covered first. Seam the front panel along the firewall followed by the back and sides. Shrink and trim off the excess. On the bottom rear fuselage, seam it aft of the wing and stretch and form a V to the tail. Then tack down and seal the sides. Shrink it and trim off any excess using a steel rule. Depending on the model, let about 1/8 to 1/4 in. overlap upwards onto the sides.
The first step in applying the white film to the fuselage is to attach the rear portion of the white side strip over the yellow. The white nose portion then overlaps the rear side strip. The easiest way to attach this strip and much of the other trim on the model is to use Windex, a method that can “virtually” eliminate air bubbles between layers of film. Spray a light coat of Windex on the plastic, align the white film where you want it, and squeegee out the excess Windex with a credit card. Then clean up or work out any remaining Windex with a tissue.
Pushing the credit card rather than dragging it works better and the edge of it can be used quite effectively to nudge pieces of film into place. If you do have any persistent air bubbles, prick them with a sharp pin and work out the air. Let one side dry over night before doing the other side or you may regret it. If it overlaps an edge, such as the leading or trailing edge, tack the film to that edge with a trim iron. When the film is dry you can use very low heat on a covering iron to set the adhesive in the trim film and then seal the edges with trim solvent. If a piece does not look right when dried, it can usually be easily lifted, sprayed and repositioned.
To apply the white film on nose of the fuselage, make a poster board pattern to cut away the yellow under it leaving about 1/8 for an overlap. Align the cut film to the stripe and tack it. Then, stretch it carefully and tack along the edges of the nose. Shrink it with an iron or a heat gun. The red film trim strip was applied with Windex in the same manner as the white side stripe it overlaps.
The fin and stabilizer are always fun parts because they mean the covering job is nearing its end and your “brand new” airplane is nearly ready to take to the air. For the white and red film on the fin and stabilizer, cardboard patterns were made and the white film was then applied using the Windex method.
Finishing Touches
To finish off the wings, 1/4 in. red trim was cut from film in strips and curves using a very sharp hobby razor knife. The cardboard patterns for the curves were made easily with help from a Hobbico circle cutter. All red trim was applied using Windex, the adhesive set with an iron at low heat, and then sealed using trim solvent.
At this point we decided to deviate from the plan and add red, 1/8 in. Great Planes Kwik Stripe striping tape on top of the white side stripe and 1/16 in. white tape along the back edge of the tail surfaces to echo the line formed on the wings. Once the airplane was done, it felt like it really needed one more stripe to complete the trim scheme. Striping tape was a fast and easy way to do it. We also cut the black canopy down in both height and length; giving it a sleeker appearance.
More Resources
Many of the techniques listed were developed by the author. Some of them were learned from the books listed below:
- Radio Control Model Airplanes, by John Carroll, Kalmbach Books
- There are No Secrets, by Harry Higley, Harry B. Higley & Sons, Inc
- Tom’s Techniques, by Tom Ingram and Harry Higley, Harry B. Higley & Sons, Inc
- Covering R/C Airplanes, Volume I, by Faye Stilley, Model Airplane News
- Covering R/C Airplanes, Volume II, by Faye Stilley, Model Airplane News