Can You Fly a Real Airplane Made Entirely of Cardboard?

Cardboard Airplane Construction and Testing

• 💡 Research and Design: The creator, with extensive experience in building model and full-size airplanes, skipped initial design phases, relying on existing knowledge for the cardboard airplane's shape and size.
• 🔬 Material Testing: Initial tests focused on cardboard flute orientation (vertical, sideways, mixed) to determine the most resilient structure for spars and ribs, finding that mixed flutes offered the best resilience.
• 🛠️ Wing Spars and Ribs: Spars were constructed using mixed flutes for maximum strength. Ribs were laser-cut, and the design emphasized an open, strong structure to minimize weight, boxing up cardboard and reinforcing key areas.
• ⚖️ Weight Management: To ensure the structure was light enough to fly, the design was intentionally made open, with cardboard boxed and reinforced only in critical areas. The goal was to use as little material as possible.
• 💥 Wing Destructive Testing: Wings were subjected to load testing, withstanding up to 140 lbs, indicating a solid structure despite being made of cardboard.

Fuselage and Tail Assembly

• 📦 Fuselage Build: The fuselage was designed like an oversized RC airplane, with pieces cut and glued together. The bottom was reinforced, and a double-layered top skin with internal cardboard slats was added for strength.
• ⚖️ Weight Check: The initial fuselage build weighed 17 lbs, considered light for its size.
• 🪵 Structural Reinforcement: While aiming for a 95% cardboard construction, small amounts of wood (plywood) were incorporated for mounting points, particularly for attaching wings with bolts, to ensure structural integrity and ease of transport.
• ✈️ Tail Section: The horizontal stabilizer and elevator were constructed from double-layered cardboard, utilizing the skin as a structural element to resist twisting. The rudder was also made from cardboard, proving lightweight and strong.
• 🔗 Flying Wires and Reinforcements: To prevent the tail section from ripping out, flying wires were added, creating a triangulated truss system from the front and back of the fuselage to the stabilizer's edge.

Power Systems and Flight Preparation

• 🚀 Motor Assembly: Four motors were installed, providing approximately 120 lbs of thrust, deemed sufficient for the cardboard airplane.
• ⚡ Battery Configuration: Initial battery wiring resulted in a short circuit due to incorrect polarity, requiring a 45-minute correction.
• 🕹️ Control System: A fly-by-wire wireless system was chosen over manual controls due to the cardboard structure's limitations. This system uses RC receivers and a controller, with redundancy built-in by isolating motor controls and half of the elevator to one receiver, and the rudder and other half of the elevator to a second receiver.
• ⚙️ Landing Gear: A jettisonable landing gear system was designed, made from a car chassis, to drop away once airborne, reducing drag. The initial wheels had high rolling resistance in grass.
• 🚗 Towing System: A car was used to tow the airplane for takeoff, with a pin mechanism to release the sled once airborne. This was an alternative to relying solely on the wheels for initial acceleration.
• 🔋 Power Upgrade: New, larger batteries from Buddy RC were installed to increase electrical power, addressing comments about potential drag issues.
• 📜 Legality: The project is confirmed to be legal under Part 103 ultralight operations, with the airframe weighing under 254 lbs and designed to meet stall speed and airspeed regulations.

Test Flights and Outcome

• 💨 First Test Flight: The initial attempt involved a ground roll, but the plane was underpowered and the wheels had too much drag. The propellers broke in the mud.
• 🛠️ Repairs and Improvements: Wings were repaired due to water damage. A new, lighter landing gear assembly made of chromoly steel was built, along with an upgraded release hitch.
• ✈️ Second Test Flight: The plane was towed again, and this time, it successfully achieved flight. The creator flew it low, aiming to maximize flight time while minimizing wing stress.
• 🌳 Accident and Landing: The flight ended when the pilot attempted a turn, ran out of airspeed, and crashed into a small brim of trees. Despite the impact, the pilot walked away unharmed due to the low speed and the nature of the crash.
• ✅ Project Conclusion: The project was deemed a success, proving that a cardboard airplane could indeed fly, though it was not a good idea. The pilot emphasized the importance of finding a larger open space for future attempts.