Glossary of gyroplane terms

How it flies

Autorotation

The rotor spinning under the force of air flowing up through the disc, rather than being driven by the engine. It is the principle a gyroplane flies on continuously, and the state a helicopter enters after an engine failure.

Gyroplane also Gyrocopter, autogyro, gyro

A rotorcraft whose rotor is turned by airflow rather than by the engine, with a separate propeller providing thrust. Regulators generally use "gyroplane"; autogyro and gyrocopter mean the same aircraft. Rotorcraft is the wider category and includes helicopters, so it is not a synonym.

Autogyro also Autogiro, gyro

Another name for a gyroplane. The same aircraft, not a different one. "Autogiro" with an i was Juan de la Cierva's trade name for his machines; the spelling with a y became the ordinary word and is still common in older books and outside the United States.

Gyrocopter also Gyro

Another name for a gyroplane, and the one most people search for. It came into use as a trade name and spread to mean the type generally. Regulators write "gyroplane"; almost everyone else says gyrocopter, and they mean the same machine.

Rotorcraft

The category of aircraft that get their lift from rotating blades rather than fixed wings. It covers helicopters and gyroplanes both, so it is a wider word than either: every gyroplane is a rotorcraft, and so is every helicopter, but a rotorcraft is not necessarily a gyroplane.

Rotor disc

The circle swept by the turning rotor blades. Much of how a gyroplane handles comes down to how the disc is tilted and how much air is flowing through it.

Prerotation

Spinning the rotor up mechanically before takeoff, so the blades are already turning when the ground roll begins. It shortens the roll; it is not what keeps the rotor turning in flight.

Rotor RPM also Rrpm

How fast the rotor is turning. Managing it is central to flying a gyroplane, and the acceptable range is specific to the type. The figures that matter are in the aircraft flight manual for your aircraft, not in a general reference.

Blowback

The rotor disc tilting back as airspeed increases, a natural consequence of the airflow through it.

Power push over also PPO, bunt over

A loss-of-control event associated with unloading the rotor while thrust is applied, more likely on certain airframe geometries. It appears repeatedly in accident reports, which is why type-specific instruction matters. Treat any general description, including this one, as background rather than as training.

Center line thrust also CLT

A design where the propeller thrust line passes through, or very close to, the aircraft's center of gravity. Adding or reducing power on a true CLT design has little effect on pitch, and the design is not subject to a power push over the way a high thrust line design is. Most gyroplanes are not built this way; a high thrust line, paired with a proper stabiliser, is the more common modern layout instead.

High thrust line also HTL, non-CLT

A design where the propeller thrust line sits above the center of gravity, the layout most modern gyroplanes use. Adding power pitches the nose down and reducing it pitches the nose up, an effect a properly sized horizontal stabiliser is designed to counter. It is the layout behind the power push over failure mode, engineered around on today's designs, not eliminated outright.

Mast bumping

The rotor hub striking its teeter stops hard enough to damage the mast, a structural failure caused by excessive rotor flapping. It is not the same thing as a power push over: a power push over is an aerodynamic event, a nose-down pitch caused by unloading the rotor under thrust, while mast bumping is the structural consequence when flapping goes far enough to hit the stops. The two terms get conflated constantly, including on a teetering-rotor helicopter, where the word is used more often than on a gyroplane.

Pilot induced oscillation also PIO

Over-controlling in pitch or roll, where each correction arrives late and too large, so the aircraft oscillates instead of settling. It is a distinct problem from a power push over or mast bumping: a piloting-technique issue, not an aerodynamic or structural one, and it is one of the more common struggles in early gyroplane training.

The machine

Rotor head

The assembly at the top of the mast that carries the rotor blades and allows the disc to tilt. One of the components a pre-purchase inspection should look at closely.

Mast

The vertical structure carrying the rotor head above the airframe.

Pusher configuration

Engine and propeller mounted behind the cabin, pushing rather than pulling. The common arrangement on modern gyroplanes.

Enclosed and open cockpit

Whether the cabin has a full enclosure or the occupants sit in the open air behind a windscreen. Affects comfort, useful season and, usually, price.

Tandem and side-by-side

Whether the two seats are one behind the other or next to each other. Affects instruction, loading and cabin width.

Empty mass also Empty weight

The mass of the aircraft without fuel, occupants or baggage. Subtracting it from the maximum take-off mass gives what you can actually carry.

Maximum take-off mass also MTOM, MTOW

The heaviest the aircraft may be at the start of the takeoff roll. A limit set for the type and, in some countries, capped further by the category the aircraft is registered in.

Buying and owning

Airframe hours

Total hours flown by the airframe since it was built. Read it alongside engine hours: the two are often very different, and both should match the logbooks.

Time since overhaul also TSO

Hours flown since a component, usually the engine, was last overhauled. It is a different number from TBO, the interval the manufacturer sets before the next overhaul is due, and a real future cost to price into any purchase.

TBO also Time between overhaul, time before overhaul

The interval, set by the engine manufacturer, at which an overhaul is due. It is different from time since overhaul, which is how many of those hours have already been flown against that interval. Rotax, the engine brand in almost every gyroplane on the market, currently sets a 2000-hour TBO on its 912 and 914 series, or 15 years, whichever comes first. Confirm the number for a specific engine in its own maintenance manual, since Rotax has changed this figure before.

Airworthiness directive also AD

A mandatory instruction from a civil aviation authority requiring an inspection or modification on a type. Ask which ones apply and whether they have been carried out. Compliance is not optional and it can ground an aircraft.

Service bulletin also SB

A manufacturer notice recommending or requiring work. Whether it is mandatory depends on the authority and the category the aircraft sits in.

Logbook

The maintenance record for the airframe and engine. A gap in it is a negotiating point at best and a reason to walk away at worst. Verify advertised hours against it before agreeing a price.

Kit build

An aircraft assembled from a manufacturer kit rather than delivered complete. Build quality varies with the builder, which is why who assembled it is worth asking about.

Price on request also POR

A listing with no published price. On this site a price-on-request listing carries no price field at all rather than a hidden or placeholder figure.

Lien

A registered financial claim against the aircraft. In several jurisdictions it follows the airframe rather than the seller, so it can become the buyer's problem. Search for one before money moves.

Flying it

Type rating and conversion

Training specific to an aircraft type, taken in addition to the licence itself. What is required, and whether existing fixed-wing or helicopter hours count toward it, is set by your national authority.

Currency

Having flown recently enough to meet the requirements that let you carry passengers or act as pilot in command. The thresholds are national and they change; check yours.

Approval reference

The identifier a flight school publishes to show it is approved to instruct. This site reproduces what a school publishes and does not verify that it is current. Confirm it with the authority that issued it.

Parts and hardware

Engine also Powerplant

The overwhelming majority of gyroplanes on the market today, across every manufacturer we track, are powered by an Austrian-built Rotax four-stroke: the 912, 914, 915 iS or 916 iS. All four are flat, four-cylinder engines with a reduction gearbox built into the case. Older and homebuilt designs sometimes use other engines, but Rotax is the type most instructors and mechanics in this category already know.

Engine manufacturer also Motor brand

Rotax, an Austrian manufacturer, powers every model published on our manufacturer directory today. It was not always the standard. Early homebuilt Bensen-style gyrocopters commonly ran a McCulloch engine, and some American kit designs use Lycoming or Continental engines built for fixed-wing aircraft instead. Confirm the actual engine fitted to any specific aircraft instead of assuming it from the airframe brand.

Horsepower also Engine power, HP

A measure of the engine's power output. It varies by engine model, not by the airframe around it, so two different gyroplanes fitted with the same engine option have the same horsepower on paper regardless of brand. Across the Rotax range this fleet uses, published figures run from around 80hp on the entry-level 912 UL up to roughly 160hp on the turbocharged 916 iS. Check the specific model's engine option on our manufacturer directory instead of assuming a figure from the airframe name alone.

Rotax engine family also Rotax engine designations

The number identifies the engine generation, 912, 914, 915 or 916, and the letters after it identify how that engine is fed. UL and ULS are carbureted and naturally aspirated. The 914 adds a turbocharger to the 912-generation core. iS models, 912 iS, 915 iS and 916 iS, are fuel injected instead of carbureted, and the 915 iS and 916 iS are turbocharged as well. Generally, the higher the number, the newer the design and the more power it makes.

Ignition system

A dual electronic ignition, two independent capacitor discharge modules each firing its own set of spark plugs. It is a redundancy feature, not a performance one: either circuit alone can keep the engine running if the other fails. Standard on every Rotax engine used in this fleet.

Spark plug

NGK plugs, in the specific heat range the engine manufacturer specifies for that model. Rotax names the exact plug for each engine variant in its maintenance manual, and it is not interchangeable with an automotive plug bought on assumption. Confirm the part number against the engine's own manual before replacing one.

Carburetor also Carb

On the original Rotax 912 and 914 variants, two Bing constant-depression carburetors, one per cylinder bank. Rotax replaced carburetors with electronic fuel injection starting with the 912 iS, and every 915 iS and 916 iS is fuel injected, not carbureted. Which one a specific aircraft has depends entirely on the engine variant fitted.

Fuel injection also EFI

Electronically controlled fuel injection, standard on the Rotax 912 iS, 915 iS and 916 iS engines, replacing the carburetors used on earlier Rotax variants. It manages mixture automatically as altitude and temperature change, without the pilot leaning a carburetor by hand.

Fuel pump

A mechanical pump driven off the engine is standard on Rotax installations. Many installations add an electric backup pump wired to run during takeoff, landing and any maneuvering, so a mechanical pump failure does not leave the engine unfed at the moment it matters most.

Fuel filter also Gascolator

Usually more than one, in a chain: a coarse strainer at the tank outlet, a gascolator, a clear sediment bowl at the system's low point that traps water and debris and is checked at every annual, and a fine filter just ahead of the engine-driven pump. Each does a different job, so one is not a substitute for another.

Oil filter

A spin-on cartridge filter, the same basic format used on countless small engines, but built to the specific bypass pressure and flow rate the engine manufacturer specifies. Rotax publishes a genuine part number for its 912 and 914 series, and substituting an uncertified automotive filter is a documented cause of oil pressure problems.

Cooling system

On the Rotax 912 and 914 series, a hybrid of both: the cylinder heads are liquid-cooled through a small radiator and coolant loop, while the cylinders themselves are cooled directly by ram air. It is a distinctive design choice, not a compromise, allowing tighter tolerances and more power than a fully air-cooled engine of the same weight.

Reduction gearbox also PSRU

A gear reduction between the engine's crankshaft and the propeller shaft, so the propeller turns at a fraction of engine speed. Without it, a propeller spinning at typical Rotax redline would have supersonic tip speeds. It is built into the engine case on every Rotax variant used in this fleet, not a separate add-on unit.

Propeller

Most factory and kit gyroplanes carry a composite, ground-adjustable pusher propeller, its pitch set on the ground and not adjustable in flight, from manufacturers such as Sensenich, Warp Drive and Airmaster. Pusher means the propeller sits behind the cabin, pushing instead of pulling, the layout nearly every modern gyroplane uses.

Pre-rotator also Prerotator drive

The mechanism that spins the rotor up before takeoff. Most designs use a mechanical belt drive off the engine with a clutch the pilot engages and disengages by hand. Electric motor-driven pre-rotators are a newer alternative appearing on some designs. Either way it only works on the ground, since the drive disengages before flight.

Rotor blades

Either an aluminum extrusion or a composite layup, on a two-blade teetering rotor, the design nearly every gyroplane on the market uses, tracing back to Bensen's original layout. The two blades are matched to each other in manufacturing and are not interchangeable with a blade from a different set without rebalancing.

Airframe also Fuselage frame

Most commonly welded 4130 chromium-molybdenum steel tube, known in the industry as chromoly, sometimes combined with bolted 6061 aluminum tube in the same structure. It is the same basic material tradition used across light homebuilt aircraft generally, not something unique to gyroplanes.

Landing gear

Fixed tricycle gear, a nosewheel and two main wheels, on nearly every design in this category. Retractable gear is not a feature of this class of aircraft.

Nosewheel steering

The nosewheel is usually free-castering, not linked to the rudder pedals, so steering on the ground comes from differential braking, tapping the left or right wheel brake to turn that way. It takes some relearning for a pilot used to a fixed-wing nosewheel steered directly by the rudder pedals.

Brakes

Hydraulic disc brakes on the main wheels, operated independently left and right, which is what makes differential-braking nosewheel steering possible in the first place.

Battery

Traditionally a sealed lead-acid battery of the AGM type, the same maintenance-free format used across small aircraft generally. Lightweight lithium-iron-phosphate batteries are increasingly offered as an alternative, trading a higher price for a substantial weight saving.

Alternator also Generator

An engine-driven alternator, built into the Rotax engine case, charging the battery and powering the aircraft's electrical system in flight the same way a car's alternator does.

Cyclic control stick also Cyclic, joystick

The stick connected by control rods to the rotor head, tilting the rotor disc to control pitch and roll. It is the gyroplane's equivalent of a fixed-wing control stick or a helicopter's cyclic, and on most designs it is the same stick used for both axes at once.

Rudder pedals

Yaw, through the rudder, the same function they serve on a fixed-wing aircraft. On many gyroplanes the pedals also operate the wheel brakes, toe brakes at the top of the same pedal used for the rudder.

Avionics and instruments

Glass cockpit also EFIS, electronic flight instrument system

A digital flight display that replaces the traditional round-dial gauges, showing airspeed, altitude, attitude and engine data on one or more screens. On experimental and light-sport gyroplanes, the common options are Garmin's G3X Touch and G5, and Dynon's SkyView and D-series, built for this category. Garmin's G1000, common in certified general aviation aircraft, is a different, more expensive system and not what you will typically find in this fleet.

ADS-B Out

Equipment that broadcasts an aircraft's GPS position, altitude and speed to ground stations and other aircraft once a second. The FAA requires it for flight in specific classes of US airspace under 14 CFR 91.225. The rule and the airspace it covers can both change, so confirm current requirements for where you fly directly with the FAA.

ADS-B In

Receiving free traffic and weather data broadcast over the same ADS-B system, through a panel-mounted or portable receiver. Unlike ADS-B Out, it is not mandated equipment anywhere in US airspace. It is a safety and convenience option a pilot can add on top of whatever the aircraft is required to carry.

Transponder

A radio unit that replies to ground radar with the aircraft's identity and altitude. Most ADS-B Out installations are built around an existing transponder, adding the broadcast function to it, and most aircraft flying in controlled airspace carry one regardless of ADS-B equipage.

Rotor tachometer also RRPM gauge

The gauge showing rotor RPM, a reading with no equivalent on a fixed-wing aircraft and one a gyroplane pilot watches as closely as airspeed. It is often combined with the engine tachometer in a single dual-needle instrument, fed by a Hall-effect sensor at the rotor head, not the engine.

Radio also COM radio

A VHF air band radio for talking to air traffic control and other aircraft, the same equipment and frequencies used across general aviation. Handheld and panel-mounted versions are both common in this category.

Intercom

A system letting pilot and passenger hear each other and the radio over engine and wind noise, wired into their headsets. It matters more on an open-cockpit gyroplane than in most aircraft, since wind noise alone can make unaided conversation difficult.

GPS navigator

Panel-mounted GPS is often built into the same glass cockpit display that shows flight and engine data, instead of a separate box. Portable and tablet-based GPS, running an aviation app, is also common, particularly on simpler or older panels.

Engine monitor also EMS

A display reading cylinder head and exhaust gas temperature, oil temperature and pressure, and voltage, replacing a row of separate round gauges with one screen. On Rotax-powered gyroplanes it is commonly built into the same glass cockpit display used for flight instruments, instead of sold as its own separate unit.

What is deliberately not here

Typical figures. There is no entry giving a usual rotor diameter, cruise speed or empty mass, because those vary by type and an average invented for a glossary is exactly the kind of number this site refuses to publish. Type figures live on the manufacturer pages, sourced individually.

Licence requirements. They differ by country and they change. The training directory lists schools by country; your national civil aviation authority is the only source that counts.

Once you have read a few of these, the knowledge quiz draws questions from them at random. Every answer links back to the term it came from.