Radio Control: Pylon Racing
Bill Hager 4 Holly Springs Dr. Conroe, TX 77302
Formula I Pylon, Part Two
This month I'll present Part Two on finishing your Formula One Pylon Racing plane, by Gary McPike:
Now that the primer is sanded off, it's time to think about colors. Choose your colors carefully. I recommend using a light base color with a medium trim. I do not recommend dark colors. They hold heat and can fry radios and melt wing foam if left out in the direct sun for too long.
Maybe this is a good time to stop and talk about the paint. You may be painting with one of the model epoxy paints, K&B Superpoxy, Hobbypoxy, or perhaps Pactra's Formula U. However, there are several builders around the country who are using automotive acrylic-enamels and acrylic-urethane paints.
Automotive paints have both advantages and disadvantages, but I feel that the advantages outweigh the disadvantages by a long shot. There are more colors to choose from; if you see a great color on a car, just go to your automotive paint dealer and buy a quart. The most you will pay is about nine dollars for a quart as opposed to $20.00 for the same amount of hobby paint.
Automotive paints are less critical as far as preparation and atmospheric temperature and humidity are concerned. An automotive paint shop does not shut down if it is too cold or if it is raining. The paint manufacturer has developed additives for cold and wet weather. You can find everything from paint retarders to accelerators for hot and cold weather. Every manufacturer markets fisheye preventer or some additive for wet weather. (I have painted planes with great results when the real fog was thicker than the spray gun fog!) You can even get special blenders that will melt the fresh overspray when you repair. It works so well that you cannot find the patch job when it is dry!
The one major negative factor about automotive acrylic-enamels is that they are not fuel-proof against the high-nitro fuels that we are using. But, with a final clear coat of acrylic-urethane to cover the paint and give the plane a high gloss, you get the best of both worlds. There is not much written about these paints, so if you decide to try them, you should do some experimenting with reducers and additives.
The paint that I use is Ditzler Delstar Acrylic Enamel, which is a two-part paint. The additive is not necessary unless you are going to paint several colors or coats in a short period of time. This is unlike cars, which get one coat and are then force-dried at 180°F for four hours before being driven out the door. I have found that double additive works well, increases the gloss and is totally fuel-proof with the urethane.
Ditzler is not the only good automotive paint on the market. Every paint manufacturing company has an acrylic-enamel and acrylic-urethane available. As a suggestion to someone who might like to try this type of paint, I would recommend going to several paint stores and asking questions. When you find someone who doesn't throw you out the door, pump him dry. Find out what the most common paint is in your area, and use that brand.
I leave what you paint with to you. Use whatever you feel comfortable with. However, there is no substitute for careful preparation. The paint will show everything that is under it. If you try to fill nooks and crannies or building mistakes with paint, thinking that you can sand it smooth with the primer or base color coat, think again. The paint will shrink as it cures, and there are all those dings and rough spots back that haunt you for the life of the airplane.
Before you mix up the paint for your base color, sit down and think about your color scheme. A good one should provide a balance of trim color. I have found that a color scheme with the lightest colors on top (of the fuselage) or at the tips of the wings, growing darker as you come down the wings or fuselage, is very effective.
A very good bit of advice was given to me years ago by a paint professor, Jeff Berken: "Always lay out your trim lines so you can patch the paint job after your first coat is up. Don't try to make your paint scheme too elaborate; you would be surprised what you can do with straight lines and some creative matching of color."
Checkerboards are one of the nicest trim ideas you can use and are one of the fastest to lay out. Using a piece of good-quality plastic contact paper on your wing or tail, mark out the vertical and horizontal lines and cut out the squares. Paint the lighter squares first, let them dry, then remove the paper squares and spray the remaining color. Be careful not to cut through the paint when removing the squares. Touch up any small imperfections with a fine brush and then apply a final clear coat.
Fine striping tape or pinstriping tape will give you a crisp line. Do not use masking tapes that leave a gummy residue; use only tapes designed for painting.
But I'm getting ahead of myself. After you have a paint scheme worked out that you like, draw it on a three-view and pin it on the wall. Look at it for a few days while you are putting the base color on and doing the color sanding. If it still looks good, then use it. However, you will probably want to change it after staring at it for a few days.
Your spray equipment is as important as the surface preparation. A good spray gun in proper working order won't save a poorly prepared surface, but it will really lay down a smooth coat of paint on a properly prepared wing or fuselage. I use a professional painter's touch-up gun with an eight-ounce cup. My compressor is a Sears 3/4-hp unit with a good-quality water trap and regulator. All the trim painting I do is with a Binks air brush equipped with a B tip.
Get out your alcohol and clean the plane. Then clean it again. Take an old toothbrush and get into the hinge lines. Next, blow off the whole plane inside and out at the highest pressure your compressor will pump. Then go over the plane again with a good epoxy-compatible tack rag.
The base color should be shot (sprayed) in two stages: a light first or tack coat, then 15 minutes later a good wet coat to cover the entire plane with an even color. No transparent spots should be showing at this point. The trick to painting a good and lightweight base color is to know when to stop. It's so easy to keep loading on the paint, but every pass of the spray gun is weight you're putting on the airplane, so paint in a good light and stop when you cannot see through the color to the exposed fiberglass and primer under it. Clean your gun and walk away from the plane for a day or two. Let it dry out of the dust.
If you are painting with a gloss hobby paint and are not going to use a clear coat over it, you are ready to do your trim layout now. I use a flattening additive in my base color, and it seems to cover better with less paint. It also dries a bit faster than high gloss.
Now that the paint has been cured for a day or two, it's time to color-sand it. Using 500-grit wet paper and soapy water, sand the whole airplane. Use a sanding block and focus only on removing dust nibs and runs. Watch the edges and high points on the cowl and wheel pants. You can sand through the color layer in a few strokes.
Now that you have the whole plane sanded down smooth again, get that three-view down off the wall. If it still looks good, start laying it out on the airplane. I recommend Scotch Fine Line Masking Tape. It's a light green color, flexible, and leaves a clean line. You can get it at any good auto paint store in widths of 3/32 to 3/4 in. I lay out the whole trim scheme in soft pencil before I put any tape on the plane. Some people can eyeball a trim job, but I can't.
You should be able to lay out the entire trim scheme with the spacing between colors planned so that you do not have to remask for each color. A 1/8-in. line between colors looks good and provides contrast as well as making the trim job go faster.
After you have all the trim masking down, take a good-quality art eraser and get all the pencil lines off the area to be painted with trim color. Then, with cheap paper masking tape and good-quality paper (butcher's paper works well), mask off all the base color. Pick the color you are going to shoot first and mask all the other areas with tape and paper. Clean the exposed surfaces well with methanol alcohol, and go over the surface to be painted with a tack rag.
Mix up your trim color and shoot it on. If you are using a touch-up gun, shoot a very light tack coat, then a light color coat. You don't need a lot of paint to get color, and you don't want to build up too much paint around the masking tape. It just has to be sanded off again. If you are using an air brush, just a light wet coat will do. You only need to put on enough paint to get a uniform color.
After the first color has dried, pull the masking tape and paper off the area of the second color and mask the first color. Clean and go over this area with a tack rag and paint it. If there is a third or fourth color, just repeat the procedure.
As soon as the last color has tacked up (about one hour), start stripping off all the masking. Then sit back and admire your handiwork. Let the plane set for another day or two. Then, with 600-grit wet paper and soapy water, carefully sand the trim. Do not use a sanding block; just knock the nubs and dust off. A good technique is to sand across the trim lines at about a 45-degree angle to the edges. This will take the excess paint off around the edges where it has built up next to the masking tape.
Don't worry. Just mask off the area around the boo-boo and spot-paint it. Let it dry, and sand again.
In the next issue, we will cover the clear coat, fading techniques, and the final airplane setup.
The most frequent questions I am asked are: "How do I find out more about Pylon racing in my area?" "What kits are available?" and "What is the latest information?" Well, other than just reading this column, why not join the organization that is responsible for all that we have today: the National Miniature Pylon Racing Association (NMPRA).
Write to: Ron Schorr 5224 Teasdale North Hollywood, CA 91607
See you next month.
Transcribed from original scans by AI. Minor OCR errors may remain.
