HX-15 Stirling Engine Helicopter Model - Walnut Base STEM Physics Toy with Dual Propellers & Glass Pistons Air-Powered Helicopter Motion Demonstration Premium Black Walnut Wooden Base 100% Rust-Proof Glass Cylinder Technology Thermal Efficiency Pro Opposed dual-chamber system separates hot/cold zones, maintaining 30% longer thermal differential for stable rotor rotation (4+ mins continuous operation) Helicopter Kinetic Theater 4-bevel gear transmission converts vertical motion to: 320RPM main rotor (14cm lift blade) 900RPM tail rotor (3.5cm directional control) Perfect for demonstrating angular momentum principles Craftsmanship Solid black walnut base houses 10 industrial bearings - weighs 0.88lbs for vibration-free desk display Function: This product is a spare part and requires DIY assembly, complete spare parts, simple structure and easy assembly. The Stirling engine is creatively combined with the helicopter model. The model is novel and unique. The Stirling engine provides power to drive the helicopter. The product comes with assembly instructions drawings and installation tools, please refer to the instructions for DIY assembly. Place the assembled Stirling helicopter model on a horizontal table or the ground, add about 2/3 of the alcohol to the alcohol lamp, light the alcohol lamp and place it under the heating cylinder to preheat for 30 seconds, and turn the flywheel by hand to assist the start, thereby driving the engine helicopter is walking. This product can be used as a teaching aid or a popular science educational toy to understand and learn the structure and principle of Stirling engine. Make your children fall in love with science through an intuitive experience. It is also an excellent gift for family, friends or children. Tips: Use 95% alcohol (not included) for fuel, and do not add water, kerosene, gasoline, lighter oil, liquor, etc.