Structures and components for helicopters falling within this main group and/or appended subgroups are additionally attributed the symbol B64C 27/04.

As an example, a helicopter fuselage with crash absorbing frames would be attributed the symbols B64C 1/062 and B64C 27/04.

Complete fuselage shapes for obtaining aerodynamic effects, e.g. reduced drag.

Fuselage bulkheads: B64C 1/10

Specifically for wings: B64C 3/185

Interior liners for aesthetic and/or protective purposes generally following the shape of the fuselage and visible from the inside in the completed fuselage.

Complete fuselage structures (frames, stringers, skin) with the emphasis on structural features.

Assembling (e.g. moving, positioning) fuselage components (e.g. barrels) into a complete fuselage: B64F 5/10

Constructional features specially adapted for the nose of the fuselage.

Constructional features specially adapted for the aft end of the fuselage.

Aircraft fuselage bulkheads such as pressure bulkheads.

Skins specifically for wings: B64C 3/26

Aircraft skin structures with integral lightning protection features are concurrently attributed the symbols B64C 1/12 and B64D 45/02 (aircraft lightning protectors).

Other structures integral with the fuselage to facilitate loading (e.g. cargo bays, cranes): B64C 1/22

Doors or door arrangements specially adapted to restrict unauthorized access are classified in this place (B64C 1/1469) and in B64D 45/0028 (multiple classification).

Equipment for handling freight in aircraft: B64D 9/00 - B64D 9/003

Also includes pyrotechnics for shattering canopies.

Details of the mounting of the antenna or radome to the fuselage, e.g. hinged connections for maintenance purposes

Cooling of the external fuselage skin.

Illustrative example of subject matter classified in this group:

Shape of wing(s) when viewed from the front, e.g. dihedral, anhedral, gull-wing.

For fuselages: B64C 1/065

For fuselages: B64C 1/12

Inflatable structural components for fuselages: B64C 1/34

Cooling of the external wing skin

Illustrative example of subject matter classified in this group (variation of camber by inflatable elements):

Illustrative example of subject matter classified in this group (wing skins are elastic; morphing, see also Glossary of Terms):

Illustrative example of variation of camber by movable elements:

This subgroup also includes documents where additionally wing skins are elastic (morphing; see also Glossary of Terms):

Integral leading or trailing edge parts of wings forming flaps by being movable by (elastic) deformation.

Folding wings or elements thereof to provide variable aerodynamic lift.

Illustrative example of subject matter classified in this group:

Folding or collapsible wings or elements thereof to reduce overall aircraft size for storage, as typically used by aircraft on aircraft carriers or by trailerable aircraft.

Substantially fixed stabilising structures such as tailplanes, noseplanes and fins. Adjustable stabilising structures only when adjustment is limited and not for primary control purposes, e.g. an adjustable tail plane.

Canard-type aircraft: B64C 39/12

Also some winglets

Variable wing sweep: B64C 3/40

For example horizontal stabilisers with limited movement about a spanwise axis for pitch trim.

Mounting control surfaces: B64C 9/02

Helicopter rotor hub fairings are concurrently attributed the symbols B64C 7/00 and B64C 27/04

Control surfaces such as rudders, ailerons, flaps, elevators, trim/servo tabs and air brakes, as well as their mounting and balancing.

Mechanical (hinged, sliding) connections between control surfaces (e.g. aileron) and supporting part (wings).

Gap covers and seals.

Structures and fairings not otherwise provided for: B64C 7/00

For example flaperons

Mainly actuating connections and linkages in the region of the flap and the supporting structure (e.g. wing), as well as further details such as covers. Aerodynamic (airflow) aspects are attributed B64C 9/18 (single flaps) or B64C 9/20 (multiple flaps).

This and the associated subgroups also covers trailing edge flaps where no slot is formed (e.g. conventional split flaps)

Mainly actuating connections and linkages in the region of the flap and the supporting structure (e.g. wing), as well as further details such as covers. Aerodynamic (airflow) aspects are attributed B64C 9/24 (single flaps) or B64C 9/26 (multiple flaps).

This and the associated subgroups also covers leading edge flaps where no slot is formed (e.g. conventional Krüger flaps).

Stabilising surfaces for retraction against or within fuselage or nacelle: B64C 5/12

Illustrative examples of jet flaps:

Propellers and associated components are only attributed B64C 11/00 or associated subgroup symbols when they are disclosed as being for use with aircraft, generally for producing longitudinal thrust.

Mainly wooden blades.

Mainly metal blades.

Mainly composite blades.

This and the associated subgroups B64C 11/48 and B64C 11/50 can also cover multiple propellers of the "unducted fan" or "open rotor" type.

Control sticks and yokes as well as associated components and details in the region thereof.

Initiating means in rotorcraft: B64C 27/56

For example longitudinal adjustment of rudder pedal assemblies.

Artificial feel (e.g. "force feedback") in the transmitting system: mechanical B64C 13/345, fluid B64C 13/46, electric B64C 13/507

Devices characterized by having two inputs actuated to effect control.

For example, locking a yoke against the dashboard to lock the control surfaces against wind gusts.

Also covers for example automatic rudder/aileron deflection to counter asymmetric thrust.

Automatic or condition responsive initiating members in rotorcraft: B64C 27/57.

Fly-by-wire or fly-by-light: B64C 13/503.

Automatic or condition responsive initiating members in aircraft power plant control: B64D 31/06 - B64D 31/12.

Autopilots, stability augmentation systems, yaw dampers, mostly in the context of the whole or a major part of the transmitting system.

For example radio control

For example unmanned aerial vehicles, which can also be flown by a pilot (e.g. aircraft converted to "drones" or aerial targets).

Transmitting means between the initiating means (e.g. control stick) and the control surface (e.g. aileron).

Documents relating to power amplifying actuators (fluid, electric, mechanic) in aircraft control surfaces transmitting means are attributed this and the symbols of the associated subclasses when their use, mounting and/or function in the context of the transmitting means as a whole is described.

Only intermeshing toothed gearing.

Automatically activated personal initiating means: B64C 13/16 - B64C 13/22.

Automatic or condition responsive personal initiating members in rotorcraft: B64C 27/57.

Automatic or condition responsive initiating members in aircraft power plant control: B64D 31/06 - B64D 31/12.

Personally activated initiating means with warning devices (e.g. "stick shakers", tactile cueing): B64C 13/10.

Also covers fly-by-light.

Control of aircraft by jet(s) generated by any means (including propellers).

Thrust vectoring.

See also B64D 33/04 for arrangements of exhaust outlets or jet pipes.

Thrust vectoring obtained by rotating the power unit as a whole.

Aircraft control obtained by using dedicated jets.

This group contains documents concerning aircraft stabilisation which are not classified in e.g. B64C 5/00.

Stability control by e.g. shifting the CoG

Pendulum stability is achieved when the centre of lift is above the CoG of the aircraft, or by using a dedicated pendulum.

A gyro is used to directly stabilize the aircraft.

Displacement of the CoG, aimed at reaching a desired trim condition, is achieved by fuel transfer between the internal tanks of the aircraft.

Control of aircraft by using e.g. gyroscopic effects, vortex generators, moving aircraft parts and/or surfaces not provided for in B64C 9/00 or, in general, systems not provided for in B64C 13/00 or B64C 15/00.

Manual or automatic controller(s) on board one or more aircraft, embodying manual inputs or automatic control logic for aircraft sub-units of different type or different function, send(s) control signals to actuators of two or more aircraft sub-units, so that the sub-units act together to solve a particular problem or in response to a particular flying condition, e.g. in order to improve stability, comfort or safety, by managing the global dynamics of the one or more aircraft.

Illustrative examples of subject matter classified in this group:

This area relates to aircraft control, function and dynamics of aircraft flying.

Classification concerning control of position, course or altitude will be placed in G05D 1/00.

Dual control apparatuses should be placed in B64C 13/12.

Any device/method operating within the airfoil boundary layer to influence the air flow around the airfoil, especially in order to control boundary layer separation.

Propulsion arrangements which ingest some or all of the aircraft surface boundary layer.

Illustrative example of the subject matter classified in this group:

Illustrative example of the subject matter classified in this group:

Cavities, slots, holes along a structural surface whereby the net flow is null.

Fluid is blown and sucked.

Fluid is only blown.

Fluid is only sucked.

Fluid flow is explicitly adjustable by, e.g. valves, variable aperture or slot area, variable pump action or fluid pressure.

Always classify, in the case of blown or sucked fluid, also in B64C 21/025 or B64C 21/04 or B64C 21/06.

The properties referred to are e.g. roughness or riblets.

Air-flow over aircraft surfaces influenced e.g. by magnetic, electric or piezoelectric panels, by static charges, by ultrasound, by special shape, by rotating bodies.

Also B64C 21/00 if boundary layer explicitly involved.

Circulation control airfoils: B64C 3/141

Using Magnus effect: B64C 23/08

Shock wave modification devices and methods. Reduction of shock drag as main searched technical effect.

Devices of any type (winglets, fins, turbines, splines) arranged at the wing tip.

Helicopter rotor blades tips: B64C 27/463

Fins on wings: B64C 5/08

A wing tip airfoil device is any separately identifiable airfoil member at the tip of the wing which creates or contributes in affecting vortices.

Devices having a cylindrical or spherical form which explicitly generate a force by using the Magnus effect.

Circulation control airfoils: B64C 3/141

Arrangement or disposition on aircraft with respect to the aircraft structure. Inter-relationship thereof.

Systems for opening and closing undercarriage door bays. Fairings in general whose movement is performed in conjunction with the landing gear movement.

General methods and systems for operating unspecified aircraft landing gears.

Operating mechanisms comprising levers, pulleys, cables, gear wheels and/or characterised essentially by the kinematic aspects of the retracting/folding displacement.

Locking mechanisms: B64C 25/26

Operating mechanisms characterised by the control circuits/operating actuators being hydraulic or pneumatic.

Operating mechanisms characterised by using electrical or electromagnetic actuators.

Uplock assemblies for retaining and releasing landing gear systems, bracing locking devices, undercarriage locking and unlocking systems in general.

Operating systems, mechanical aspects: B64C 25/20

Ground lock detection devices, landing gear warning systems, landing gear verification systems.

Emergy release/actuation actuators and relevant control.

Illustrative example of endless-track type ground-engaging element:

Pre-landing acceleration devices for aircraft wheels, generally passive.

Motorised wheels, any type of motor or installation thereof.

Originally meant for covering, e.g. thrust reversers, it is no longer used in this respect.

Thrust reversers shall not be classified in this group.

Braking methods/systems wherein the braking sequence is controlled by an electronic control unit and performed in accordance with predetermined steps, including controlling the brakes independently, to achieve a predetermined target, e.g. to achieve a predetermined deceleration rate or to optimize the braking force.

Regulators, disks, valves.

Undercarriages which can be steered, relevant control systems and actuators, steering angle warning systems.

Wheel shimmy is a condition in which the landing gear wheel or wheels oscillate from side to side along a straight line parallel to the direction of travel of the aircraft. Documents concerning this problem are classified here.

Skis, skids, runners, various ground engaging structures, especially suitable for helicopters.

Safety devices for helicopters: B64C 27/006

Illustrative example of subject matter classified in this group:

Any shock absorber comprising hydraulic or pneumatic cylinders.

The ground engaging elements can be converted from e.g. wheeled to floats or skis and vice-versa depending on the specific landing surface.

Capturing or retrieving systems on aircraft.

Vibration or noise damping by means of isolators on the rotor head, suspended masses, actuators acting on the complete rotor assembly or active noise cancellation.

For example wire cutters or detectors, helicopter-specific use of airbags, distance sensors for tail booms, rotor blade crack detection, tail rotor guards, emergency tail rotor drives or emergency anti-torque means.

Aircraft emergency devices: B64D 25/00

For example rotor blade tip weights or rotor blade tracking apparatus and methods.

The following helicopter components are not attributed any of the symbols in B64C 27/00 but only the symbol B64C 27/04 and one of the following associated, applicable symbols:

Fuselage structures and windows:B64C 1/00 - B64C 1/40

Rotor hub fairings:B64C 7/00

Armament:B64D 7/00 - B64D 7/08

Underslung loads: B64D 1/22

Mounting cameras: B64D 47/08

Drives which transfer motor output to the rotors at a generally 1:1 ratio.

Illustrative examples of subject matter classified in this group:

1.

2.

Mostly tiltrotor aircraft requiring an anti-torque tail rotor.

Rotor hubs, special or unconventional rotors.

Flexbeams for rigid rotors.

Root attachment to rotor head: B64C 27/48

Elastomeric joints for articulated rotors

Root attachment of propeller blades: B64C 11/04 - B64C 11/12

Foldable propeller blades: B64C 11/28

For autogyros: B64C 27/022

Transmitting means for controlling lead-lag movement of rotor blades: B64C 27/635

Cyclic sticks and collective levers as well as associated components and details in the region thereof.

Can also cover maintaining hover position or attitude.

Automatic or condition responsive initiating members in aeroplanes: B64C 13/16 - B64C 13/22

Fly-by-wire or fly-by-light: B64C 13/503

Automatic or condition responsive initiating members in aircraft power plant control: B64D 31/06 - B64D 31/12

Transmitting means downstream of the cyclic stick and the collective lever.

Individual blade control by acting directly on the blade, e.g. by a separate actuator for each blade.

Vertical take-off and landing (VTOL) aircraft, e.g. of the tiltrotor types.

Also covers horizontal propeller/blower and airflow deflector.

Also covers accessories for gliders (e.g. insect removal from leading edges) which cannot be adequately classified elsewhere.

Hang-glider-type aircraft; Microlight-type aircraft, i.e. mainly very simple and light, powered single or two-seat aircraft with an open frame fuselage, but also covers light, single or two-seat aircraft when the emphasis is on low weight and simplicity, and/or when described as an "ultralight", "microlight" or "light sport aircraft".

Illustrative examples of subject matter classified in this group:

Example of "trike" or weight-shift controlled microlight:

Example of powered hang-glider:

For example (ballistic) parachute rescue systems specially adapted to microlight aircraft or hang-gliders.

Illustrative example of subject matter classified in this group:

Mainly unpowered hang-gliders with rigid, delta-shaped wings of the "Rogallo"-type.

Illustrative example of a delta-shaped wing:

Also covers powered, microlight aircraft when comprising details of such wings.

Microlight aircraft - mainly powered - with a parachute or parafoil type wing attached to a rigid/substantial structure (e.g. framework or rigid seat). Also covers backpack-type powerplants for paragliders.

Illustrative example of subject matter classified in this group:

Illustrative example of subject matter (backpack-powerplant) classified in this group:

Propulsive power produced by the pilot, e.g. pedals connected to a propeller.

All aircraft which fly by flapping the wings.

Illustrative example of ornithopter wings and actuating mechanism therefor:

The word "seaplane" is used to describe two types of air/water vehicles: the floatplane and the flying boat. A floatplane has slender floats, mounted under the fuselage. Two floats are common, but other configurations are possible. Only the floats of a floatplane normally come into contact with water. The fuselage remains above water. In a flying boat, the main source of buoyancy is the fuselage, which acts like a ship's hull in the water. Most flying boats have small floats mounted on their wings to keep them stable.

Comprising devices acting in the water to generate thrust and/or slow down and/or steer the aircraft (e.g. propellers, jets, rudders).

Comprising lift generating devices which are peculiar to the shape of a seaplane.

Aircraft suitable for ground and water take-off and landing.

Combined road (and/or water) /air vehicles usually provided with wheels (and/or e.g. pontoons) and in-air propelling/thrust means.

Flying units wherein (possibly after an initial engagement phase) the multitude of (possibly different) flying vehicles (possibly including ground and/or water vehicles and/or dedicated units) are permanently connected.

Essentially all the flying vehicles not classified in one of the previous groups, highly unconventional aircraft.

Flying vehicles characterised by sustainment without aerodynamic lift, engine thrust or buoyant gas. Lifting arrangements which violate the laws of physics, e.g. closed-loop systems.

Illustrative example of a flying saucer:

Illustrative example of subject matter classified in this group:

Remotely piloted flying vehicles in general.

Devices including rotors, wings, propellers, turbojets to be "worn" by a user.

Illustrative examples of subject matter classified in this group:

MAVs (microaerial vehicles), usually for military purposes, any maximum dimension of which does not exceed 15 cm (6 inches).

Aircraft that lack symmetry with respect to a longitudinal vertical plane.

Flying units formed by separate aircraft: B64C 37/02

Illustrative example of subject matter classified in this group:

Aircraft having ring-shaped wings wherein the air flow in level flight is parallel to an axis of revolution of said ring

Illustrative examples of annular wings:

Illustrative example of annular wing with radial airflow:

Illustrative example of channel wings:

Illustrative example of multiple wings joined at the tips:

This group includes e.g. the BWB (blended-wing-body)-type aircraft