This video documents the design, construction, and testing of a novel 3D-printed rotary engine, which the creator calls the "traveling chamber rotary engine." The design was conceived as a simpler alternative to a previous failed rotary vane engine, aiming to solve complex sealing issues inherent in DIY projects. The engine features two spring-loaded, half-moon-shaped "traveling chambers" that rotate within a static elliptical housing, creating intake, compression, expansion, and exhaust strokes with two combustion events per 360-degree rotation. A prototype, printed from weak PVA filament, successfully achieved two combustion events before failing due to the heat and forces generated. The creator emphasizes that this is a passion project, sharing the 3D files freely and inviting community collaboration. Future plans involve using high-temperature, reinforced filaments (PETG, PPS) to create a more durable version with the goal of achieving five seconds of sustained operation. The video also highlights the role of modern, user-friendly technology, specifically the Bambulab 3D printer and Onshape CAD software, in enabling rapid prototyping.
Inventing a New Rotary Engine: From Concept to Combustion
5:08 A New Engine Concept: The Traveling Chamber Rotary: The creator introduces his new engine, designed after his previous rotary vane engine failed due to insurmountable sealing difficulties on a DIY level.
6:57 Principle of Operation: The engine uses a static elliptical housing. Inside, two opposing, half-moon-shaped "traveling chambers" are mounted on a central rotor. As they rotate, the volume between the chambers and the housing wall changes, creating the four strokes of an internal combustion engine (intake, compression, combustion, exhaust).
8:42 Key Advantages: Simplicity and Power Density: The design offers two combustion events per revolution, providing a power stroke every 180 degrees, similar to a four-cylinder, four-stroke engine. The creator argues its main advantage is simplified sealing compared to a Wankel rotary, as only the tips and sides of the moving chambers need sealing, and the motion is purely rotational.
5:08 Proof of Concept: Two Combustion Events: A prototype printed from weak, low-temperature plastic achieved two successful combustion "farts" using RC fuel. This proved the concept was viable before the engine was destroyed by the force and heat of the events.
12:22 Open-Source Philosophy and Future Goals: The creator is not patenting the design and has made the 3D files publicly available for anyone to experiment with, driven by a love for engineering rather than profit. His goals are:
Achieve one combustion event (achieved).
Achieve 5 seconds of continuous running.
Power a small vehicle like a go-kart.
15:56 Enabling Technology: The Bambulab 3D Printer: The project was made possible by a user-friendly and fast Bambulab 3D printer, which allows for the rapid prototyping and experimentation needed for this kind of project. The creator praises its ease of use compared to the constant troubleshooting required by older CNC machines and 3D printers.
23:03 The Next Steps: Stronger Materials and Better Sealing: The creator plans to rebuild the engine using engineering-grade, high-temperature filaments like glass-reinforced PETG and carbon fiber PPS to create a version that can withstand sustained operation. He also needs to source proper sealing materials to replace the temporary rubber sheet used in the prototype.
Summary of YouTube Comments:
The comments section is overwhelmingly positive, filled with encouragement, technical advice, and community humor. Key themes include:
Widespread Encouragement and Praise: Viewers are highly supportive of the project, praising the creator's passion, curiosity, scientific approach, and open-source philosophy. Many express excitement to follow the project's development.
Technical Suggestions for Improvement: A significant number of comments offer constructive criticism and ideas. The most common suggestion is that the current design applies combustion force directly into the crankshaft, generating little to no torque. Proposed solutions include:
Offsetting the spark plug.
Adding a cavity or asymmetrical shape to the face of the traveling chamber to direct the explosion.
Using an eccentric crankshaft or cam mechanism.
Other suggestions include using cams instead of springs to control the chambers, improving the seal design with materials like graphite or roller bearings, and testing the engine with compressed air first.
3D Printing Community Advice: Fellow 3D printing enthusiasts offer practical tips, such as placing the printer on a heavy, stable surface (like a concrete paver) to reduce vibrations, and suggest alternative high-strength filaments like PPA-CF or using TPU for flexible seals.
Humor and Acronyms: The community engaged with the project humorously, with many users proposing funny acronyms for the engine (e.g., The R.E.C.T.U.M.) and making jokes about the passion-fueled chaos of the workshop.
Debate on Patenting: Opinions are split on the creator's decision not to patent the design. Many praise his open-source ethos, while others urge him to file a patent, even if just to establish prior art and prevent a "patent troll" from claiming the idea in the future.