Those who have built balsa airplanes for years or decades have a long list of shortcuts they have learned. Here are a few of mine which I think will be helpful for new builders.
Getting CA glue off of your fingers
Sand it off with your sanding block, or with a loose piece of sandpaper
Fuel proof “paint”
In 1992 a friend showed me his second airplane. This guy is actually my cousin in law, and when he does something, he does it right. His second plane was a Sig 4 Star 40 covered in yellow Monokote, and everything was perfect. The thing that really impressed me was that the cockpit and the engine compartment were glossy black. I asked him what he had painted it with, and he told me it was dope. At the time I didn’t have a ton of experience, so although the plane was very simple I found it very impressive because it was a really tidy job, and the dark color hid all of those details you don’t really want people to look at.
I never got around to using dope, but I bought a small jar of Formula U black polyurethane paint at the hobby store, and I used it for a long time to paint engine compartments, biplane struts, cockpits, etc. Thinking back on it, I remember painting a landing gear black with this stuff when I moved to Kansas City in 1996, and I used it for the last time around 2016. It was a 4 ounce jar. I wanted to buy another one, but I think it went out of production a long time ago. Probably because a single jar lasts 20 years. That’s a good product but not a good business plan.
When I realized I needed a substitute, it occurred to me that I could color my bare wood parts with permanent markers before fuel proofing them with epoxy. I found out that you can use up a black Sharpie pretty quickly this way, so I went to the dollar store and bought a big fat one with a wedge shaped tip. I’ve used it quite a bit and it isn’t showing signs of running out yet.
Here are a few planes that have received the epoxy-over-Sharpie treatment.
You can use epoxy for fuel proofing with or without applying color first. From six feet away it looks great!
Use sanding dust to fill gaps
Sometimes you glue things together and they just don’t fit. You can use gap filling CA glue, but it tends to run away somewhere before it sets, leaving a gap. So you fill the gap again and shoot it with accelerator. Typically when this is done you are left with a protruding lump of CA that needs to be sanded away. One potential solution is to stick everything together with thin CA, then sand the area around the joint. Use your fingers to push balsa dust into the crack. Brush away the excess so nothing protrudes past the surface, then use thin CA to glue the dust in the crack.
Put your wing spar where it belongs
You have to balance your plane with the correct center of gravity before you fly it. The center of gravity should be marked on the plan sheet. Most of the time it will be right on the spar, or at the rear edge of the spar. This makes it easy to balance the plane because you just put your fingers under the spar and hold the airplane up. Some designers arrange things so the spar and the CG do not coincide, which requires you to mark the CG somewhere else to balance your finished model. Make it easier for yourself. Take note of the CG location on the plans, and when you’re cutting out the wing ribs place the spar notches at the designated center of gravity. I’ve built a lot of planes like this over the years, and I always just move the spar to where it belongs.
Plastic covering for your plans
Just about every construction article will tell you to put something transparent over your plan sheet, then build the plane on top of it. Lots of people use plastic food wrap, which is just about the worst thing, or wax paper, which is a good idea if you’re using cement, but no good if you’re using CA. The best thing to use is the clear plastic backing from a roll of Monokote. Of course you’ll have to build a plane first and then cover it, and then you’ll be ready for your next building project. This plastic can be used repeatedly. I always save the backing from the wing covering on my largest building projects, which are big enough for just about anything I build.
Put wing sheeting on with the grain going in the correct direction
When you put sheeting on the leading edge of a tapered wing, don’t orient the grain so it’s parallel to the spar, like this:
Orient the grain so it is parallel to the leading edge, like this:
When the grain is diagonal to the leading edge, it tends to make a series of bumps and dips along the edge. When the grain is parallel to the leading edge it tends to lie flat, so it’s easier to make a wing with a nice, smooth surface.
Use glue dots for your center of gravity marker
Put a dot of medium CA glue on each wing at the designated center of gravity location, and give it a shot of accelerator. You can easily feel the little dot with your fingers as you hold the plane up to check the balance.