{
    "title": "One-Blade Propellers (Everel, et al.)",
    "inventor_name": "Walter Everel",
    "publication_year": null,
    "device_name": "Single-blade propeller",
    "goal": "Provide a compact, efficient aircraft propeller with higher efficiency, reduced bending and gyroscopic stress, and lower vibration.",
    "problem_addressed": "Imbalance forces, vibrations, and structural stress in conventional multi-blade propellers; need for a retractable, lightweight propulsion unit for motorized gliders.",
    "concept_summary": "A single-blade propeller paired with a diametrically opposite counterweight whose centre of gravity is axially offset. The offset (and optional pivots) creates a balancing moment that compensates centrifugal and traction forces, allowing automatic vibration reduction and efficient thrust.",
    "detailed_description": null,
    "category": "Aerodynamics & Flight",
    "principles": [
        "Counterweight balancing",
        "Axial offset of counterweight",
        "Centrifugal force based moment compensation",
        "Dynamic pivot allowing blade oscillation",
        "Variable pitch adjustment"
    ],
    "scientific_domains": [
        "Aerospace Engineering",
        "Mechanical Engineering",
        "Fluid Dynamics"
    ],
    "mechanisms_of_action": [
        "Centrifugal force on blade and counterweight generates a balancing moment",
        "Axial offset of counterweight adjusts the moment to match traction force variations",
        "Pivot mechanisms let the blade oscillate, changing the axial offset dynamically",
        "Variable pitch changes thrust without altering motor speed"
    ],
    "materials": [],
    "energy_sources": [
        "Electrical"
    ],
    "inputs": [
        "Motor torque",
        "Airflow relative to blade"
    ],
    "outputs": [
        "Thrust",
        "Rotational power output"
    ],
    "claimed_performance": "Higher efficiency, smoother operation, reduced bending and gyroscopic stress compared with conventional multi-blade propellers.",
    "experimental_evidence": null,
    "replication_status": null,
    "keywords": [
        "single-blade propeller",
        "counterweight",
        "balance",
        "glider",
        "propulsion",
        "variable pitch"
    ],
    "related_technologies": [
        "Multi-blade propeller",
        "Foldable propeller",
        "Variable-pitch propeller"
    ],
    "controversy_level": "low",
    "confidence_score": 0.9,
    "practicability_score": 0.6,
    "fringe_score": 0.2,
    "evidence_strength": 0.3,
    "risk_score": 0.2,
    "trl_estimate": 4,
    "source_urls": [
        "http://en.wikipedia.org/wiki/Single-blade_propeller",
        "http://notplanejane.com/everel.htm",
        "http://www.ladieslovetaildraggers.com/blog/no-way-a-one-bladed-propeller/",
        "https://patents.google.com/patent/US5971322"
    ],
    "organizations": [
        "Everel Propeller Corporation",
        "Beretta et al."
    ],
    "applications": [
        "Powered gliders",
        "Light aircraft",
        "Unmanned aerial vehicles (drones)"
    ],
    "limitations": [
        "Requires precise counterweight balancing",
        "Complex pivot mechanisms may increase maintenance",
        "Effectiveness may be limited to low-power applications"
    ],
    "open_questions": [
        "Long-term fatigue life of the pivot and counterweight assembly",
        "Performance at higher rotation speeds or larger aircraft",
        "Manufacturing tolerances needed for reliable automatic balancing"
    ],
    "red_flags": [],
    "evidence_quotes": [
        "The counterbalanced teetering mono-blade propeller generates fewer vibrations than conventional multiblade configurations.",
        "The counterweight being arranged in a substantially diametrical position with respect to the single blade in order to balance the moment generated by centrifugal force.",
        "The axial offset d also varies as the traction force Ft varies, providing equilibrium.",
        "The invention allows to compensate for the resulting imbalances in a very simple way, thus making this type of propulsion unit particularly adapted for application to powered gliders."
    ]
}