Advanced Tips

Tips for Advanced Flyers
on Building Great-Looking Airplanes that are Great-Flying Airplanes

As experienced control-line builders and flyers know, there is a difference between airplanes that “look great” and airplanes that “fly great.” As beginners, many builders stop after painting their airplanes with clear dope. They realize that crashes are inevitable, and feel there is no reason to spend the extra time and money on painting their airplane.

Those early airplanes generally perform well. As builders become more proficient, they decide to go ahead and paint their airplane, only to find that performance suffers. Or, they build a specific airplane, paint it and then find that their airplane does not perform as well as other versions of the same kit that were built by someone else.

The answer to what makes performance go down is that the weight of the airplane went up -- because of the paint. After all, the paint that goes onto the airplane does weigh something, even after it is spread out over the entire airplane!

In the construction process, you can improve the performance and responsiveness of an airplane by decreasing its weight. But, before you read on, here is a word of caution: as the weight of an airplane is reduced, its durability is reduced as well. In other words, as you find ways to make your airplane lighter, it will become more fragile. If you have a hard landing or a crash, there will be significantly more damage and the airplane probably will not be repairable.

With that word of caution, here are some steps that will enable you to lighten an airplane. If you are an advanced flyer, these tips may be helpful as you look for ways to improve the performance of your airplane.

One way to reduce the weight is to remove excess wood from the design. The key is to find areas where the wood can be removed without substantially weakening the design. One excellent place to begin is with the fuselage. Generally, a profile fuselage comes with squared edges. By tapering and sanding the edges of the fuselage you will reduce the overall weight. In addition, the area between the holes in the wing ribs can be cut out to form slots, reducing the weight without changing the structural strength of the ribs. Another option is to drill holes in the rear sections of the hardwood motor mounts. Again, it is a matter of judgement as to how many holes can be drilled without affecting the overall strength and performance of the motor mounts.

Another way in which to reduce the overall weight of the airplane is by sanding. As more sanding is done before parts are assembled, more weight is removed -- and less sanding has to be done during and after construction. As you are cutting away wood and sanding, remember that a lighter airplane is a less-rigid airplane. As the airplane becomes less rigid, it will be harder to work with, especially when you try to sand it. That’s why pre-sanding is very important if you are building a lighter-weight airplane.

Once the construction work and sanding are completed, cover the entire airplane with two coats of clear dope. Sand everything lightly, then add another coat of clear dope. At this point, cover the wings and the entire fuselage with Silkspan. Silkspan is one of the lightest fabrics available for covering the wings. By covering the fuselage with Silkspan, you are reducing the overall weight of the airplane in two ways: First, the Silkspan takes the place of micro-fill and weighs less. Second, it will take less paint to cover the fuselage after it has been covered with Silkspan.

Once the Silkspan is in place, put two coats of clear dope on everything, then sand very lightly with 400 + sandpaper. Remember that Silkspan is a very lightweight product and it is very easy to sand through it (or accidently stick your finger through it!). Coat the entire airplane with Brodak Primer, thinned to two parts thinner and one part primer.

Once the primer has dried completely, dry sand the airplane. Check for any spots that will require repainting, then repaint and sand as needed. After all of the spots are taken care of, give the airplane another full coat of the primer and wet sand with 400 sandpaper. You are now ready to finish your painting by adding the color coats. For best results, check our “Painting Tips from Brodak,” available where Brodak Paint Products are sold.

Every control-line builder and flyer has his or her ideas on how to reduce the weight of an airplane, and there are as many shortcuts and “tricks of the trade” as there are builders. We would love to hear about your shortcuts!