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3 Simple and Effective Balsa Wood Bridge Designs

  • 04 Oct 2022

Designing bridges is a great hands-on exercise that challenges both scientific and mathematical minds. It’s also accessible with balsa wood bridge building. This started as a hobby but has become popular enough that people now compete in bridge designing competitions. Students from many areas enter their bridges to see who has the best design. You should read on to learn more about building balsa wood bridges. Here are three simple and effective balsa wood bridge designs for you to review.

Classic K-Truss

The classic K-truss might be the most common balsa wood bridge design. It’s the most effective because it has multiple pieces that ensure the bridge’s sturdiness. The most effective design for this bridge is to have seven vertical members and six K-trusses per side.

The name comes from the obvious letter shape formed during and after the building process. Seven vertical pieces and six K-truss pieces might seem extensive, though. Contestants have used the design before with less, but these suggestions are good for whatever foundation you want.

If you build it properly, this design should take about 10 hours to complete. You can space the time out over several days because you’ll need to allow for drying time. Start with the foundation and leave plenty of time for the glue to dry before starting on the trusses.

The Pratt

The Pratt is another classic design that can support lots of weight. It’s also one of the easier designs to create because of the geometry involved. To start, you’ll need to lay a solid base vertically and horizontally because the two sides need to connect. At AC Supply, we have balsa wood bridge building kits to help with your designs.

The center of the bridge consists of triangular shapes. The balsa wood pieces all have the same dimensions, so it isn’t difficult to ensure they’re all even. Don’t use an excessive amount of glue when connecting the pieces to form the triangular shapes. This can result in the bridge collapsing when tested.

The Warren

The Warren truss bridge is another sturdy option. The design is similar to the Pratt. But where the Pratt uses an additional wooden piece in the center, the Warren does not. Without that additional centerpiece, the structure of the bridge takes on a W shape, hence the name.

The bottom base has more units than the top. It’s about one unit shorter, which is another similar characteristic to the Pratt design. Because the Warren doesn’t have that additional centerpiece, you’ll need to ensure that the bases for the top and the bottom are solid, specifically the bottom.

There are several different designs you can choose from, but if you’re looking for reliability, these three simple and effective balsa wood bridge designs will get the job done.