Avery Flies built a 27-foot radio-controlled thermal airship: a propane-heated dirigible that flies under full RC control. Lift comes from hot air, same principle as a hot air balloon, but this one has a rudder, thrust, and a pilot giving it directions.
The hardware is a specific mix of salvaged and purpose-built parts. A hand-sewn nylon envelope takes the first 15 minutes of the build video. Inflation uses a 70mm electric ducted fan. Thrust comes from a brushless DC motor spinning an 18-inch prop. The rudder servo is a winch unit pulled from an RC sailboat, chosen because the meter-scale fabric rudder behaves more like a sail than an airplane control surface. Heat comes from a propane burner fed by two standard portable barbecue tanks.
The build video is worth watching in full because the envelope fabrication and the engineering tradeoffs behind each component choice are shown, not just the flight. The propane integration and the decision to repurpose marine RC hardware for a flying machine are the details that make this more than a novelty.
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