Glossary of Terms

Compound Type
Alternatives for how lift and/or thrust compounding are employed (if any).Compounding is the use of dedicated devices to provide additional lift or thrust (other than the primary lift/thrust mechanism) during specific phases of flight. These terms are normally only applicable to helicopters but lift compounding has also been applied to autogyros with lifting wings.

Control Device Type
The type of dedicated control device on the aircraft (if any)

Crew Required
The minimum crew required to operate the aircraft (under visual and/or instrument rules). This will normally be less than the number crew required for specific mission needs.

Landing Gear Type
A simple description of the configuration of the landing gear

Lift Configuration Layout
Basic configuration of the rotors, or thrust producing devices, that provide lift in vertical or low speed flight

Number of Control Devices
The number of rotors, or other devices, dedicated to pitch, roll or yaw control in vertical and low speed flight (ignoring the primary lift systems)

Number of Engines
Number of main engines excluding APU (if fitted) used in powering the lift system

Number of Lift Devices
The number of rotors or other devices that provide primary lift in some segment of flight

Number of Propulsors
The number of devices that are solely dedicated to providing forward thrust

Seating Arrangement
The seating configuration for the required flight crew

VTOL Type
The primary category of the aircraft

Aircraft Designation
The product designation for the aircraft (minus company name)

Aircraft Notes
Any notes relevant to the specific aircraft

Aircraft Status
Choices for where the aircraft currently stands in the product life-cycle

Armament
Description of the standard armament, and armament options, for the aircraft (if any)

Design Authority
The company that holds the design and design airworthiness responsibility for the aircraft. In collaborative programs one company may act as the co-ordinating Design Authority with individual companies holding design authority for their own work share.

Primary Manufacturer
The company that manufactures the largest number of the specific aircraft

Type
The over-arching description for a Type or Family of aircraft. All aircraft of the Type will normally carry the type designation within it's own designation and are a direct derivative of the type (embodies most of the primary characteristics) or part of the product family.

Variant
The designation of a major sub-group of aircraft that have the Type characteristics (this may not always be reflected in manufacturer’s literature)

Airframe Height
The maximum height to any part of the fixed airframe from ground level including any permanently fitted equipment (note: If this dimension is not available, the closest dimension should be added with a note in the associated data point reference to explain what the dimension actually represents)

Airframe Length
The maximum length of the fixed airframe including any permanently fitted equipment (note: If this dimension is not available, the closest dimension should be added with a note in the associated data point reference to explain what the dimension actually represents)

Airframe Width
The maximum width between the fixed airframe extremities including any permanently fitted equipment (note: If this dimension is not available, the closest dimension should be added with a note in the associated data point reference to explain what the dimension actually represents)

Cabin Internal Height
The nominal height of the cabin from manufacturer's data

Cabin Internal Length
The nominal length of the cabin from manufacturer's data

Cabin Internal Width
The nominal width of the cabin from manufacturer's data

Landing Gear Base
The longitudinal distance between the center line of the front and rear wheels or the length of skids/etc of the landing gear

Landing Gear Track
The lateral distance between the center line of each pair of main wheels/skids/etc in the landing gear

Overall Height
The maximum height of the complete aircraft (with rotors turning) from ground level. This is one of the dimensions that defines the 'box' the aircraft would fit into when in the normal operating configuration.

Overall Length
The length that covers the complete aircraft (with rotors turning). This is one of the dimensions that defines the 'box' the aircraft would fit into when in the normal operating configuration.

Overall Width
The width that covers the complete aircraft (with rotors turning). This is one of the dimensions that defines the 'box' the aircraft would fit into when in the normal operating configuration.

Autogiro
A term used for any aircraft with an unpowered rotary wing either designed by Cierva or a licensee of his patents. The term must always be written with a capital 'A' and an 'i' in giro as it represents a trademark.

Autogyro
A term used for any aircraft with an unpowered rotary wing with a forward mounted tractor type propellor

Gyrocopter
A term used for any autogyro designed by Igor Bensen. The name is a trademark.

Gyroplane
In current usage, this term used for any aircraft with an unpowered rotary wing with an aft mounted pusher type propellor. It has also been been used to describe very early helicopters.

Main Rotor Blade area per blade (calculated)
The nominal area of each main rotor blade from rotor center-line to tip, calculated as the product of the input diameter/2 x input blade chord

Main Rotor Blade Chord
The nominal chord of the main rotor blade, where chord is a straight line connecting the leading and trailing edges

Main Rotor Blade Construction
Description of the construction and material(s) of the main rotor blade

Main Rotor Blade Tip Geometry
A description of the blade tip shape

Main Rotor Blade Twist
The overall twist of the main rotor blade from the main rotor axis of rotation to the blade tip (washout/tip less twisted, -ve). It can be the geometric or aerodynamic twist depending on the data source (note: it is possible, but not usual, for some rotors to have 'wash-in', which would be entered as a positive number)

Main Rotor Diameter
The diameter of the circle swept by the main rotor blades in their normal flight condition

Main Rotor Direction of Rotation
The direction of rotation of the main rotor when viewed from above

Main Rotor Disc Area (calculated)
The total area swept by the main rotor blades from rotor center line to tip (calculated)

Main Rotor Disc Loading (calculated) (DL)
The total helicopter weight (MTOW @ ISA SL) divided by the rotor disk area

Main Rotor Hub Type
A simple description of the fundamental features of the main rotor hub (e.g. the type and arrangement of hub articulations)

Main Rotor RPM
The normal operating speed of the main rotor in revolutions per minute

Main Rotor Solidity (calculated)
Ratio of total blade area (calculated) to disc area (calculated) for the main rotor

Main Rotor Tip Speed (calculated)
The speed of the main rotor blade tip in hover

Number of Main Rotor Blades
The number of main rotor blades per rotor

Hover Ceiling IGE
The maximum altitude for hover in ground effect

Hover Ceiling OGE
The maximum altitude for hover out of ground effect

Hover In Ground Effect (HIGE)
Hover with rotor height less than approximately 1 main rotor diameter above the ground

Hover Out of Ground Effect (HOGE)
Hover with rotor height greater than approximately 1 main rotor diameter above the ground

International Standard Atmosphere (ISA) Sea Level Conditions (ISA SL)
Sea Level conditions for the International Standard Atmosphere (i.e. 15 degC/59 degF at 0 ft pressure altitude)

Max Endurance
The maximum endurance with zero payload without auxiliary fuel tanks and no fuel reserve

Max Level Flight Speed (Vh)
The maximum level flight cruise speed achievable within the available power or torque limits

Max Range
The maximum range with zero payload without auxiliary fuel tanks and no fuel reserve

Max Rate of Climb
The maximum rate of climb at the highest power rating available in fwd flight

Never Exceed Speed (Vne)
The never exceed speed (which may not be level flight) - normally a structural or rotor load limit

Service Ceiling
The operational altitude (OGE) where the rate of climb (at best rate of climb speed) falls below 100 fpm

All Engines Operative (AEO)
All engines producing their normal output power levels for a multi-engined aircraft

Engine Type
The engine type (reciprocating or turbine)

Intermediate power (IRP)
The maximum power level that can be used for a defined time (typically 30 minutes) under normal conditions. This is for an un-installed engine (for the defined ambient, static conditions)

Max continuous power (MCP)
The maximum power level that can be used for an unlimited time under normal conditions. This is for an un-installed engine (for the defined ambient, static conditions)

Maximum power
The maximum power level that can be used for a defined time (typically 10 minutes) under normal conditions. This is for an un-installed engine (for the defined ambient, static conditions)

OEI 30-second power
The 30 second power rating for the uninstalled engine for OEI operation (for the defined ambient, static conditions)

OEI contingency power
The contingency power rating (normally 2 or 2.5 minutes) for the uninstalled engine when operating OEI (for the defined ambient, static conditions)

OEI continuous power
The continuous power rating for the uninstalled engine for OEI operation (for the defined ambient, static conditions)

OEI intermediate power
The intermediate power rating (normally 30 minutes) for the uninstalled engine when operating OEI (for the defined ambient, static conditions)

One Engine Inoperative (OEI)
One Engine is not providing the demanded output power in a multi-engined aircraft

Powerplant
Designation of the installed engine(s). Only engines that contribute to the lift system are currently detailed (except gyroplanes).

Take-off / rated power (TOP)
The maximum power level that can be used for a limited time (typically 5 minutes) under normal, take-off conditions. This is for an un-installed engine (for the defined ambient, static conditions)

Number of Tail Rotor Blades
The number of tail rotor blades per rotor

Tail Rotor Blade Area (per blade) (calculated)
The nominal area of each main rotor blade from rotor center-line to tip, calculated as the product of the input diameter/2 x input blade chord

Tail Rotor Blade Chord
The nominal chord of the tail rotor blade, where chord is a straight line connecting the leading and trailing edges

Tail Rotor Blade Construction
Description of the construction and material(s) of the tail rotor blade

Tail Rotor Blade Twist
The overall twist of the tail rotor blade from the tail rotor axis of rotation to the blade tip (washout/tip less twisted, -ve). It can be the geometric or aerodynamic twist depending on the data source

Tail Rotor Configuration
Direction of the tail rotor thrust (in normal flight condition) w.r.t. the tail fin/fuselage (thrust towards fin='pusher', thrust away from fin='tractor’). For shrouded or fenestron type tail rotors (and some specific tail configurations) the term ‘Unblocked’ will apply as the induced tail rotor flow does not impinge directly onto a fixed (flow blocking) surface.

Tail Rotor Diameter
The diameter of the circle swept by the tail rotor blades in their normal flight condition

Tail Rotor Direction of Rotation
Top blade aft or top blade forward

Tail Rotor Disc Area (calculated)
The total area swept by the tail rotor blades from rotor center line to tip

Tail Rotor RPM
The normal operating speed of the tail rotor in revolutions per minute

Tail Rotor Solidity (calculated)
Ratio of total blade area (calculated) to disc area (calculated) for the tail rotor

Tail Rotor Tip Speed (calculated)
The speed of the tail rotor blade tip in hover

Empty Weight
The weight of the aircraft in the standard configuration including unusable fuel, engine oils and all fixed, standard equipment

Empty Weight Fraction (calculated)
The ratio of empty weight to maximum gross weight

Max Gross Weight (airborne)
The maximum allowable weight of the aircraft for airborne load lifts, under any ambient conditions

Max Gross Weight (ground)
The maximum allowable weight of the aircraft for take-off, under any ambient conditions. Vertipedia initially assumes that Max Gross Weight (ground) equals Max Take-off Weight unless a contributor can provide a more accurate value.

Max Take-off Weight
The maximum allowable weight of the aircraft for take-off at the defined ambient conditions, normally at the rated Take-off Power limit. MTOW is also dependent on the take-off constraints (e.g. vertical T/O, rolling T/O, etc). Vertipedia initially assumes that Max Take-off Weight equals Max Gross Weight (ground) unless a contributor can provide a more accurate value.

Useful Load (calculated)
The sum of all weight components that add value for the aircraft's mission. It is the difference between the Max Take-off Weight (which may be less than the Max Gross Weight) and the Empty Weight.