8 Interesting Facts About Balsa Wood

Published: 11th June 2012
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Balsa wood is an ideal material for making model airplanes. Balsa is light, strong, affordable, easy to shape and readily available. Balsa wood has been a principle construction material for model aircraft since the 1930s and remains so today. Following are eight interesting facts about this remarkable building material.

For any aircraft, from a real world Boeing 747 to a micro indoor radio control model plane, an important factor for successful flight is low weight. The less an aircraft weighs the better the flight performance.

Once the goal of low aircraft weight is understood, it is easy to understand why balsa wood is such a popular model airplane building material. Balsa wood is lightweight, readily available and has an exceptionally high strength-to-weight ratio. Balsa can be cut, sanded and shaped with everyday hand tools. Balsa absorbs shock and vibration well, and accepts a wide variety of glues and paints.

Even full scale fighter aircraft such as the World War II de Havilland Mosquito included balsa wood in their manufacture, to conserve scarce metal resources. It is little wonder that so many types of model planes use balsa wood as their primary construction material.

Following are eight interesting facts regarding balsa wood:

Balsa Fact 1: Balsa trees are native to Central and South America. Ecuador produces over 95 percent of the world's supply of commercial balsa wood. Slightly over half of Ecuador's balsa production comes from plantations with up to 1,000 trees per hectare, as compared to around 2 to 3 trees in this same area in nature.

Balsa Fact 2: Balsa trees grow rapidly, gaining heights of up to 90 feet and a diameter of 12 to 45 inches within ten years. The speed of growth is the main reason for the lightness of the wood.

Balsa Fact 3: The secret to balsa's light weight has to do with its cellular structure. Only around 40 percent of balsa is solid material. The remaining internal portion is water.

Balsa Fact 4: Balsa wood that is harvested from nature contains five times as much water by weight when compared to the actual wood materials. Most hardwoods contain very small portions of water as part of their makeup. Green balsa wood undergoes a rigorous two week kiln drying process to lower this excess water level to around 6 percent.

Balsa Fact 5: Finished balsa wood weights can vary for a variety of reasons. These include the age and size of the tree, location of the trunk cut and the kiln drying process. Commercial balsa wood used for model airplane construction typically weighs between 6 and 18 pounds per cubic foot. The most common weights available are between 8 to 12 pounds per cubic foot. Six pounds or less is considered contest grade wood.

Balsa Fact 6: Balsa is not the world's lightest wood. There are three to four wood varieties that weigh less. However, any wood lighter than balsa is exceptionally weak and completely unsuitable for model airplane construction.

Balsa Fact 7: Because the range of balsa wood densities can vary so much, a modeler must specify the types of balsa wood desired. Use the lightest grades possible for sections of your model that do not bear weight or require strength, such as nose cowls, fill-in and shaped wing tips. Select a heavier cut of wood for areas requiring strength such as wing spars, fuselage formers and stringers.

Balsa Fact 8: There are three types of balsa grain. A-Grain contains long grain lines, is flexible across the sheet and readily bends. A-Grain is ideal for sheeting fuselages and covering wing leading edges. As the A-Grain can easily warp, do not use this grade of balsa for solid sheet wings or tail surfaces.

B-Grain shares qualities of both A and C graded balsa. B-Grain feels a bit stiffer across the sheet, and can be used for general purpose model airplane construction. The best use of B-Grain is for wing ribs, fuselage formers and planking.

C-Grain sheet balsa has a characteristic mottled appearance. C-Grain is warp-resistant, does not bend easily, and when properly used can build the lightest and strongest model plane.

Model aircraft builders are fortunate to have balsa wood readily available as a versatile and affordable construction material. Balsa can be incorporated as a major part of any aircraft's structure. The radio control model airplane hobby literally would not be possible without this remarkable material.


Tim McKay is an accomplished model airplane designer, builder and pilot. Find more information, RC model flight reviews, building tips, free plans and over 30 instructional model aircraft videos at: => http://www.IndoorFlyingModel.com

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