propeller
Enable an AI agent to recognise a propeller, assess its suitability and condition, and determine which installation, operation, adjustment or maintenance actions are supported by evidence.
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
Researched by: Codex + Grok
Purpose and description
Enable an AI agent to recognise a propeller, assess its suitability and condition, and determine which installation, operation, adjustment or maintenance actions are supported by evidence.
A propeller is a rotating open-stream actuator of two or more pitched blades on a hub that converts shaft torque into axial thrust by changing the momentum of the surrounding air or water.
It can be Identify the propeller and compare its blade, hub and pitch configuration with documented configurations.; Evaluate a proposed shaft attachment, rotation direction and installation clearance.; Compare candidate operating points with applicable performance evidence and limits.; Determine whether a proposed pitch adjustment, feathering or reversing action is supported.; Plan inspection, cleaning, balancing or repair against applicable procedures and observed condition.; Recommend continued use, restricted use, removal or specialist assessment with explicit evidence and unresolved conditions..
Distinguishing features
Establish whether its intended output is thrust for propulsion; moving fluid for ventilation or process circulation alone does not establish that it is a propeller.
Identify blades arranged around a rotation axis whose documented geometry and operating direction support a thrust-producing mode; a radial paddle or generic rotating wheel is insufficient.
Check whether the assembly normally receives shaft power to produce thrust rather than primarily extracting fluid energy as a turbine; record reversible or energy-recovery modes separately.
Distinguish the blade-and-hub assembly from a complete thruster or propulsor that also includes a drive, housing, duct or steering mechanism.
Use the registered concept and application evidence to resolve overlap with fans and lifting rotors, because appearance alone does not reliably separate these categories.
Scope
+ Identity and boundaries of the blade-and-hub assembly
+ Blade geometry, rotation convention and pitch configuration
+ Mechanical attachment and pitch-control interfaces
+ Thrust, torque, efficiency and operating limits under stated conditions
+ Blade and hub condition, balance, inspection and service eligibility
- Engine or motor internals and energy supply
- Gearbox, transmission and shaft-line design beyond the propeller interface
- Whole-vehicle handling, stability and mission planning
- Hull, airframe, duct and guard structures except their interface constraints
- Complete propulsion-system controls and certification
Characteristics
- Intended fluid and application
- Air, water or another specified fluid; documented propulsion application Determines which performance evidence, degradation mechanisms and neighbouring concepts apply.
- Blade count
- Integer count Supports recognition, configuration checks and interpretation of blade-passing excitation.
- Swept diameter
- m, with configuration and measurement method Constrains clearance, installation compatibility and interpretation of performance.
- Blade geometry
- Chord in m and section orientation in degrees versus radial position; skew, rake and section references where applicable Separates geometrically different propellers that share a diameter and nominal pitch.
- Pitch configuration
- Fixed, ground-adjustable or controllable; feathering and reversing capabilities separately evidenced Determines which pitch changes are physically available and under what conditions.
- Pitch value or blade setting
- Geometric pitch in m or blade angle in degrees, with radial station and reference convention Prevents incompatible pitch conventions from being treated as equivalent settings.
- Rotation and thrust convention
- Clockwise or counterclockwise from a named viewing direction, with positive axial thrust defined Prevents installation and operating-direction errors.
- Mounting compatibility
- Compatible shaft, flange or hub interface and required retention arrangement Establishes whether attachment is supported beyond a superficial dimensional fit.
- Operating point
- Rotational speed in rpm, torque in N·m, thrust in N, advance speed in m/s and stated fluid conditions Makes performance and load observations interpretable.
- Structural and surface condition
- Observed defect type, location and extent; assessed, unassessed or unknown disposition Connects damage evidence to applicable inspection and service limits.
- Balance and blade tracking
- Residual unbalance in a stated mass-distance unit and blade-track deviation in mm, with method and limits Supports investigation of vibration and verification after assembly or repair.
Also called
Where this came from
wikidata · CC0 1.0
Also registered as vr.tr.propeller
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 6 bundles · 11 layers · 18 findings · 28 questions.
Propeller identity Establishes what assembly is being modelled and why it qualifies as a propeller.
An agent must distinguish a propeller from visually similar rotors and from the larger propulsion equipment containing it.
Propulsive role
Identifies the intended fluid interaction and application.
Intended thrust function
Records evidence that the assembly is intended to generate propulsive thrust through rotation in a fluid.
- What documented application establishes this assembly's propulsive role and intended working fluid? definition
- What evidence distinguishes it from a circulation fan, turbine, impeller or lifting rotor in this registry? boundary
Assembly boundary
Identifies the physical configuration included in this propeller.
Blade and hub membership
Records the blades, hub and included pitch-changing parts, together with configuration identity.
- Which blades, hub components and pitch-changing parts belong to this assembly, and which belong to neighbouring equipment? boundary
- Which markings, drawings or configuration records identify the assembly and any replacement blades? provenance
Blade geometry and pitch Captures the geometry and adjustable states that determine how the propeller engages the fluid.
Diameter and a nominal pitch label alone cannot establish geometric equivalence or adjustment capability.
Blade form
Describes the swept envelope and the shape of individual blades.
Radial geometry
Records blade count, diameter and available section geometry with explicit reference conventions.
- What are the blade count and swept diameter, and to which assembled configuration do they apply? measurement
- How are chord, twist, section shape, rake and skew specified along the blade, and which remain unknown? measurement
Pitch capability
Separates pitch geometry from the means and permitted circumstances of changing it.
Pitch settings and transitions
Records pitch conventions, available settings and evidence for adjustment, feathering or reversing.
- Is pitch specified as geometric advance or blade angle, and at what radial station and reference plane? definition
- Which pitch changes are supported, over what range, and may they occur while rotating or only while stopped? action
Installation and control Connects the propeller to its drive, surrounding geometry and any pitch-control equipment.
A matching diameter or shaft opening does not establish a compatible or operable installation.
Mechanical attachment
Captures how torque and axial loads pass through the mounting interface.
Mounting and retention
Records mounting geometry, load compatibility and required retention evidence.
- Which shaft, taper, spline, key or flange specification and retention arrangement does this propeller require? definition
- What evidence supports compatibility with the proposed drive interface and its torque and axial loads? provenance
Installed orientation and actuation
Relates rotation, clearance and pitch actuation to the actual installation.
Installation operability
Records whether the installed orientation and available interfaces support the intended operation.
- From which viewing direction is rotation specified, which way is intended thrust, and what clearances are required and measured? measurement
- If pitch is controllable, which actuation interface, feedback and loss-of-actuation behaviour are documented for this assembly? definition
Performance and operating envelope Links thrust production and loading to operating conditions and applicable limits.
Propeller performance depends on the operating point, fluid and installation; an isolated thrust or efficiency value is insufficient.
Operating-point evidence
Makes measured or predicted performance traceable to conditions and methods.
Thrust, torque and efficiency
Records performance observations or predictions without treating them as universal properties.
- At what rotational speed, pitch setting, advance speed, fluid conditions and installation were thrust and torque established? measurement
- Were the results measured or predicted, and what efficiency definition, uncertainty and applicability accompany them? provenance
Operating constraints
Captures limits and fluid-specific phenomena that constrain acceptable use.
Limits and adverse regimes
Records supported speed and load limits and relevant evidence for cavitation, ventilation, compressibility or vibration restrictions.
- Which speed, torque, power, pitch and environmental limits apply to this exact configuration, and where are they established? provenance
- Which adverse operating regimes are relevant in this fluid and installation, and what documented response applies when their indicators appear? action
Condition and service decisions Connects blade and hub observations, operating history and maintenance evidence to service decisions.
A propeller may remain recognisable while damage, imbalance or consumed life prevents its intended use.
Damage and rotation quality
Records local defects and assembly-level rotation measurements.
Blade and hub condition
Captures observed damage, material-relevant inspection evidence, balance and blade tracking.
- What cracks, deformation, erosion, corrosion, delamination or attachment defects were observed, where, and by which applicable inspection method? measurement
- What balance and blade-track results are available, and how do they compare with limits applicable to this configuration? measurement
Service disposition
Determines what use or intervention is justified by the available records.
Continued use and intervention
Links service history and applicable procedures to continued operation, repair or removal.
- What operating exposure, impact or overspeed events, repairs and applicable life limits are recorded, and what history is missing? provenance
- Given the recorded condition and history, which continued-use, restriction, repair or removal decision is supported, and what verification is required before return to service? action
Evidence and external alignment What the world already says about this thing, gathered so the model can be checked against it.
A model that cannot be lined up against existing standards, identifiers and practice cannot be adopted by anyone who already uses them.
Reported evidence
Findings from the breadth pass, kept separate from the structural claims.
Kinds and varieties
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Fixed-pitch screw propeller (marine FPP or aircraft fixed-pitch)
- Controllable-pitch propeller (CPP), including reversing marine screws
- Constant-speed aircraft propeller (governor-controlled, often feathering and/or reversing)
- Ducted propeller / Kort-nozzle propeller
- Contra-rotating propeller
- Folding or sailing-feathering yacht propeller
- Surface-piercing or supercavitating propeller
- Azimuthing / podded propeller
- Which of these kinds and varieties hold for the sense of propeller this model covers, and on what evidence? provenance
Identifiers and schemes
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Wikidata item - Q131407 - Generic item for the rotating-blade propulsor; aircraft and marine senses are not split at this Q-id.
- Harmonized System (HS) - 8487.10 - Ships' or boats' propellers and blades therefor.
- FAA propeller type certificate / TCDS - P followed by digits and a dash-letter series (e.g. P-920), as listed on an FAA Type Certificate Data Sheet - Identifies a certificated aircraft propeller model, not a marine screw.
- ISO 3715 term - ISO 3715-1 vocabulary for ship screw propellers - Standardised English (and equivalent) terms for marine screw geometry and types, not a serial identifier of a single object.
- Which of these identifiers and schemes hold for the sense of propeller this model covers, and on what evidence? provenance
Standards and regulation
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- ISO 484-1 / ISO 484-2 - manufacturing tolerances for ship screw propellers by diameter class (International Organization for Standardization)
- ISO 3715-1 - vocabulary for ship screw propellers in propulsion plants (International Organization for Standardization)
- 14 CFR Part 35 - airworthiness standards for aircraft propellers (FAA, United States)
- EASA CS-P - certification specifications for propellers (European Union Aviation Safety Agency)
- Classification-society rules for propeller materials, scantlings, keying and inspection (e.g. DNV, ABS, Lloyd's Register; aligned in part with IACS)
- ITTC recommended procedures for propeller open-water and cavitation tests (International Towing Tank Conference)
- Which of these standards and regulation hold for the sense of propeller this model covers, and on what evidence? provenance
Real-world use
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Main screw of merchant ships, warships, tugs and workboats, usually bronze or nickel-aluminium bronze, driven by diesel, turbine or electric shaft lines.
- Outboard, sterndrive and inboard propellers on recreational and small commercial craft, often aluminium or stainless steel, specified by diameter × pitch in inches.
- Tractor or pusher propellers on piston and turboprop aeroplanes, and on many UAVs, converting engine power to thrust in air.
- Harbour and station-keeping units: tunnel bow/stern thrusters and azimuthing/podded propellers.
- Sailing yachts: folding or feathering propellers that reduce drag under sail.
- High-speed craft and some racing hydroplanes: surface-piercing or supercavitating screws that run partly in air or in a vapour cavity.
- Which of these real-world use hold for the sense of propeller this model covers, and on what evidence? provenance
Typical measurements
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Diameter - 0.05-0.4 (small UAV); 0.3-0.8 (small craft); 1.8-2.2 (light aeroplane); 2-11 (ship screws, occasionally larger) - m
- Geometric pitch - about 0.5-1.5 times diameter; small-craft pitch commonly quoted as 8-24 - m (or inches in recreational marine/aircraft trade)
- Blade number - 2-3 (light aircraft, small boats); 4-7 (ships, high-power CPP) - count
- Expanded blade-area ratio (EAR / BAR) - 0.3-0.6 (low-loaded screws); 0.7-1.2 (high-power or cavitation-limited) - dimensionless
- Rotational speed - 60-200 (large ship); 300-1500 (small marine); 1800-2700 (light aircraft); 5000-40000 (small UAV) - rpm
- Open-water efficiency η0 - 0.50-0.75 typical installed; up to about 0.80-0.85 in favourable open-water conditions - dimensionless
- Advance ratio J = Va/(nD) - 0.4-1.2 in the usual operating region of marine screws - dimensionless
- Which of these typical measurements hold for the sense of propeller this model covers, and on what evidence? provenance
Failure modes and hazards
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Cavitation erosion of marine blade faces and trailing edges, with noise, vibration and thrust breakdown.
- High-cycle fatigue cracking at the blade root, fillet or hub, leading to blade throw (aircraft and marine).
- Aircraft ground strike, foreign-object damage or bird impact; resulting imbalance can destroy the engine or airframe.
- Overspeed or runaway if a constant-speed governor or CPP pitch actuator fails; feathering failure after engine stop.
- Dezincification, galvanic corrosion and shaft-taper fretting on copper-alloy marine propellers.
- Fouling, rope or net entanglement, and impact with debris or ice, causing bent blades and shaft misalignment.
- Singing (vortex-induced trailing-edge vibration) and hull-pressure pulse excitation of the afterbody.
- Personnel hazard from an unguarded rotating disc, especially on boats in gear and on unsecured aircraft on the ground.
- Which of these failure modes and hazards hold for the sense of propeller this model covers, and on what evidence? provenance
Regional variation
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- British marine and historical aeronautical English still uses "screw" (and older "airscrew") where North American practice says "propeller" or "prop".
- Recreational marine markets in the US specify diameter and pitch in inches; metric diameter in millimetres is common in Europe and on ISO drawings.
- Kort-nozzle ducts and Voith-Schneider cycloidal units are far more common on European tugs and inland vessels than on typical US workboats, which more often use open screws or azimuthing Z-drives.
- Classification-society material and inspection practice (ABS, DNV, LR, CCS, ClassNK) is the de facto marine standard in each flag's usual class, rather than a single global propeller code.
- Which of these regional variation hold for the sense of propeller this model covers, and on what evidence? provenance
Neighbouring kinds and how to tell them apart
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Impeller - An impeller is designed to work inside a close-fitting casing as a pump or compressor stage; a propeller is an open- or duct-stream actuator whose blades interact with a free fluid.
- Fan - A fan is sized for volume flow and low pressure rise (ventilation, cooling); a propeller is sized for net axial thrust on a vehicle or equivalent free-stream load.
- Helicopter rotor - A main rotor produces primarily lift with cyclic and collective pitch over a large disc; a propeller produces primarily axial thrust with (at most) collective pitch change and no cyclic control.
- Waterjet - A waterjet ingests water internally and ejects it through a steering nozzle; there is no exposed screw in the free stream, though the internal pump may use an impeller.
- Paddle wheel - A paddle wheel uses radial boards or floats at the free surface and very low rpm; a screw propeller is a submerged helical blade system.
- Wind-turbine rotor - A wind turbine extracts energy from the flow (generator on the shaft); a propeller puts energy into the flow (engine or motor on the shaft).
- Cycloidal (Voith-Schneider) propulsor - Vertical-axis blades with timed pitch give vectored thrust without a conventional helical screw; it is often classed with propellers in ship lists but is a different mechanism.
- Which of these neighbouring kinds and how to tell them apart hold for the sense of propeller this model covers, and on what evidence? provenance
Sources
- Marine Propellers and Propulsion (John Carlton; Butterworth-Heinemann / Elsevier) - Marine kinds (FPP, CPP, ducted, contra-rotating, surface-piercing), geometry quantities (diameter, pitch, blade-area ratio, skew, rake), cavitation and strength failure modes, and ITTC-style open-water performance language.
- 14 CFR Part 35 - Airworthiness Standards: Propellers (Federal Aviation Administration / U.S. eCFR) - Aircraft propeller as a certificated product; fatigue, overspeed, bird-impact and pitch-control hazards; type-certificate identification of aircraft propellers.
- ISO 484-1 - Shipbuilding - Ship screw propellers - Manufacturing tolerances - Part 1: Propellers of diameter greater than 2,5 m (International Organization for Standardization) - Marine screw-propeller as a manufactured object with standardised diameter classes, pitch and geometry tolerances, and foundry/machining practice.
- CS-P - Certification Specifications for Propellers (European Union Aviation Safety Agency) - European airworthiness requirements for aircraft propellers, parallel to 14 CFR Part 35, including feathering, reversing and governor-related failure cases.
What the second pass must settle
- Does the existing Vercy catalogue already cover propellers within a world model that should remain the single source of truth?
- Where does this registry place the boundaries between propellers, ducted fans, lifting rotors and pump-jet rotor assemblies?
- Should separately replaceable blades and controllable-pitch hub mechanisms receive linked models, and how should their individual histories compose into assembly condition?
- Which authoritative application-specific sources should establish terminology, performance conventions, inspection criteria and operating limits for air and water propellers?
- Do paired counter-rotating or folding propellers require additional assembly relationships or configuration states beyond those proposed here?