{
    "title": "Toroidal Propeller",
    "inventor_name": "Thomas Sebastian & Christopher Strem",
    "publication_year": 2023,
    "device_name": "Toroidal Propeller",
    "goal": "Reduce acoustic noise and improve safety of multirotor drones while maintaining comparable thrust.",
    "problem_addressed": "High noise levels and safety hazards of conventional drone propellers that can cut or collide with objects.",
    "concept_summary": "A closed-form toroidal propeller that curves the tip of a leading blade into contact with a trailing blade, creating a looped, stiff structure that reduces tip vortices and acoustic signature while delivering thrust comparable to conventional propellers.",
    "detailed_description": "The toroidal propeller consists of a hub supporting multiple elongate blade elements whose leading-edge tips curve around to meet trailing-edge elements, forming a continuous loop. This geometry increases structural stiffness and encloses the rotating blades, which diminishes tip-vortex formation and thus lowers the frequency range most audible to humans. The design can be fabricated via additive manufacturing (e.g., PETG or PLA 3-D printing), allowing customization for various multirotor platforms. Test installations on commercial drones have demonstrated thrust comparable to standard propellers with a noticeable reduction in perceived noise.",
    "category": "Aerodynamics & Flight",
    "principles": [
        "Aerodynamic loop",
        "Acoustic attenuation",
        "Structural stiffness through closed geometry",
        "Additive manufacturing customization"
    ],
    "scientific_domains": [
        "Aerodynamics",
        "Acoustics",
        "Mechanical Engineering",
        "Materials Science"
    ],
    "mechanisms_of_action": [
        "Enclosing blade tips to suppress tip vortices",
        "Looped blade geometry increasing stiffness",
        "Reduced blade-air interaction noise"
    ],
    "materials": [
        "PETG",
        "PLA",
        "Thermoplastic polymer"
    ],
    "energy_sources": [],
    "inputs": [
        "Rotational mechanical power from drone motor",
        "Ambient air flow"
    ],
    "outputs": [
        "Thrust",
        "Reduced acoustic noise"
    ],
    "claimed_performance": "Thrust comparable to conventional multirotor propellers while decreasing noise in the most human-sensitive frequency range.",
    "experimental_evidence": "Toroidal propellers were installed on a commercial drone for testing; multiple videos demonstrate quieter operation and comparable lift.",
    "replication_status": "Tested on a commercial drone (prototype level).",
    "keywords": [
        "toroidal propeller",
        "drone",
        "noise reduction",
        "additive manufacturing",
        "UAV",
        "acoustic signature",
        "thrust",
        "efficiency"
    ],
    "related_technologies": [
        "Conventional drone propeller",
        "Ducted fan",
        "3-D printed propeller"
    ],
    "controversy_level": "low",
    "confidence_score": 0.9,
    "practicability_score": 0.8,
    "fringe_score": 0.1,
    "evidence_strength": 0.6,
    "risk_score": 0.2,
    "trl_estimate": 6,
    "source_urls": [
        "http://ow.ly/yWA150MkbPwhttps://www.ll.mit.edu/sites/default/files/other/doc/2023-02/TVO_Technology_Highlight_41_Toroidal_Propeller.pdf",
        "https://worldwide.espacenet.com/publicationDetails/biblio?DB=EPODOC&II=0&ND=3&adjacent=true&locale=en_EP&FT=D&date=20190509&CC=US&NR=2019135410A1&KC=A1#",
        "https://www.youtube.com/watch?v=E8L8I0dLh_o",
        "https://www.youtube.com/watch?v=MGy8jvf-DZ0",
        "https://newatlas.com/aircraft/toroidal-quiet-propellers/"
    ],
    "organizations": [
        "MIT Lincoln Laboratory",
        "Sharrow",
        "RexResearch"
    ],
    "applications": [
        "Aerial delivery drones",
        "Cinematography UAVs",
        "Industrial infrastructure inspection",
        "Agricultural monitoring",
        "Quiet marine propellers for boats",
        "Electric flying taxis",
        "Computer cooling fans"
    ],
    "limitations": [
        "Manufacturing complexity for larger scales",
        "Material strength limits of 3-D printed plastics",
        "Limited quantitative performance data",
        "Potential durability concerns under high-speed operation"
    ],
    "open_questions": [
        "Exact decibel reduction compared to conventional propellers",
        "Efficiency gains across different sizes and speeds",
        "Long-term material fatigue and wear",
        "Scalability to larger aircraft or marine vessels"
    ],
    "red_flags": [],
    "evidence_quotes": [
        "The toroidal propeller allows a small multirotor unpiloted aircraft, or drone, to operate more quietly than current drones that use propeller forms unchanged since the beginning of aviation.",
        "Achieves thrust comparable to that of a multirotor drone propeller.",
        "Toroidal propellers were installed on a commercial drone for testing.",
        "The propeller includes a hub supporting a plurality of elongate propeller elements in which a tip of a leading propeller element curves into contact with a trailing propeller element to form a closed structure with increased stiffness and reduced acoustic signature."
    ]
}