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COMPETITIONS

WEC Junior Design

Finding energy beyond the elastic bands.

  • Mechanism design
  • Flexures
  • Design tradeoffs
The crossbow-inspired launcher made from wooden sticks, cardboard and elastic bands.
Our loaded launcher, built from the supplied craft materials.

A crossbow-inspired launcher that stored energy in wooden flexures as well as elastic bands, built under material and weight constraints.

The space-themed Junior Design task was to launch a Nerf dart as far as possible. The launcher had to remain loaded until a trigger was pressed, and weight was part of the judging.

My contribution

  • Propose the crossbow-inspired launch concept.
  • Explore energy storage in bending wooden sticks.
  • Contribute to the team’s supplied-material build.
01 / THE PROCESS

Using the wood as a spring

Most of the concepts we saw relied on elastic bands for stored energy. I proposed bending the popsicle-stick structure itself into large wooden flexures, with elastics connected to their ends.

The resulting crossbow-like arrangement stored energy in both the wood and bands. A clothespin provided the trigger so the launcher could sit ready before release.

02 / THE PROCESS

Range was only one part of the brief

Our launcher achieved the longest shot in the division as I remember it, but it was heavy. Weight and presentation penalties brought our overall result to sixth.

The project is a compact example of a design tradeoff: optimizing one visible performance measure does not automatically satisfy the whole set of requirements.

WHERE IT LANDED

A strong launch, with a tradeoff.

The flexure concept distinguished our launcher, while the sixth-place overall result reflected criteria beyond range. Weight and presentation mattered alongside the mechanism’s performance.

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