Post 9: Why I'm Filling my Fuselage With Air (and a Little Purple Foam)
- UL Plans
- Apr 20
- 1 min read
April 20, 2026
The Canyon Lightning™ backbone is officially reinforced with its structural carbon wrap. Now it's time to lock in the rigidity of the rear fuselage before the final gussets go on.
The technique:
I'm custom-fitting 1" XPS foam inserts into every open bay of the Douglas Fir truss. Think of this as the shear web of an I-beam.
Why do this before the final gussets?
1️⃣Precision fit: I can trim the foam to be perfectly flush with the 1x1 longerons, ensuring the final foam layer and carbon wrap later have a dead-flat surface to bond to.
2️⃣Mechanical lock: By gusseting the second side after the foam is in, the foam is permanently trapped. It can't move, vibrate, or shift.
3️⃣Weight vs. strength: This adds almost zero weight, but it prevents the wood sticks from buckling or bowing under G loads.
Note: I'm leaving the very aft section open for now. That's where the stab and fin get integrated and unitized with their own carbon wrap.
One step at a time I'm building a lighter, stiffer, and more affordable way to fly ⚡
Follow me for more! Watch the build come along and don't miss the test flight or the plan release! Thanks for your support.
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