Introduction to Aircraft Structural Design

Vocabulary flashcards covering basic aircraft definitions, categories, certification parameters, structural stresses, flight control surfaces, structural components, and major zones.

Aircraft

A vehicle capable of flight by obtaining support from air, operating within the atmosphere.

Aerostat

The technical term for a lighter-than-air aircraft kept aloft by gas, such as helium, hydrogen, or heated air.

Aerodyne

The technical term for a heavier-than-air aircraft that depends on aerodynamic lift and powered lift.

Category of Aircraft (Airmen Certification)

A broad designation identifying the basic type of aircraft to group them by key characteristics, use, and operating limitations for pilot certification.

Class of Aircraft

A grouping of aircraft within the same category that share similar operating, propulsion, in-flight handling, or landing characteristics.

Acrobatic Aircraft Category

An aircraft certification category with minimal flight maneuvering restrictions, seating up to nine passengers plus pilot, and a maximum weight of $12,500\,\text{pounds}$.

Commuter Aircraft Category

A multi-engine and propeller-driven aircraft certification category seating up to 19 passengers with a maximum weight below $19,000\,\text{pounds}$.

Normal Aircraft Category

An aircraft category not approved for acrobatic flight, with seating for nine or fewer persons and a maximum takeoff weight of $12,500\,\text{pounds}$.

Transport Aircraft Category

An aircraft certification category rated by engine type, exceeding $12,500\,\text{pounds}$ and 10 seats for jets, or $19,000\,\text{pounds}$ and 19 people for piston engines.

Utility Aircraft Category

An aircraft certification category seating up to nine passengers plus pilot, weighing up to $12,500\,\text{pounds}$, authorized for limited aerobatic maneuvers.

Restricted Aircraft Category

Aircraft built specifically for special operations like agricultural spraying, forest conservation, aerial surveying, or weather control.

Provisional Aircraft Category

Aircraft certified for a limited duration, issued as Class I for 24 months or Class II for 12 months.

Aircraft Approach Category

An aircraft grouping based on maximum takeoff weight (MTOW) that determines the required final landing approach speed $V_{\text{REF}}$

Category A Approach Speed

An aircraft approach category with an indicated airspeed of less than $91\,\text{knots}$.

Category B Approach Speed

An aircraft approach category with an indicated airspeed from $91\,\text{knots}$ up to less than $121\,\text{knots}$.

Category C Approach Speed

An aircraft approach category with an indicated airspeed from $121\,\text{knots}$ up to less than $141\,\text{knots}$.

Category D Approach Speed

An aircraft approach category with an indicated airspeed from $141\,\text{knots}$ up to less than $166\,\text{knots}$.

Category E Approach Speed

An aircraft approach category with an indicated airspeed from $166\,\text{knots}$ up to less than $211\,\text{knots}$.

Tension

A tensile stress that stretches and elongates structural material due to outward pulling forces acting in opposite directions.

Compression

A stress that squeezes, crushes, or shortens material due to inward pushing forces acting in opposite directions.

Torsion

An internal twisting shear stress created around an object's longitudinal axis by a turning force called torque.

Shear Stress

A force acting parallel to the surface of a material that causes internal layers to slide past one another.

Bending Stress

An internal stress developed when an external load creates a bending moment, causing one side to stretch in tension and the opposite side to compress.

Strength of Structure

The structural capability of an aircraft to resist applied internal and external loads and stresses.

Fuselage

The main structural body of a fixed-wing aircraft serving as the central attachment point for the wings, empennage, landing gear, and powerplant.

Truss Type Fuselage

A rigid framework composed of beams, struts, and bars designed to resist deformation, generally covered with fabric.

Monocoque Construction

A single-shell fuselage construction relying primarily on the skin to carry primary loads, using formers, frames, and bulkheads for shape.

Semi-Monocoque Construction

A fuselage design modifying monocoque construction by stiffening the load-bearing skin with longitudinal members like stringers and longerons.

Longeron

The principal longitudinal structural member in a semi-monocoque fuselage that helps the skin support primary bending loads.

Stringer

A structural member that stiffens the skin in compression and transmits skin loads to body frames or wing ribs.

Bulkhead

A heavy internal frame in a fuselage used to maintain shape, resist loads, and contain pressure.

Spar

The principal spanwise structural member of a wing that carries aerodynamic loads from ribs to the fuselage and resists bending.

Rib

A chordwise structural member shaped as an airfoil that gives form to the wing and transfers aerodynamic loads from skin to spar.

Monoplane

An airplane designed with a single set of wings.

Biplane

An airplane designed with two sets of wings.

Semicantilever Wing

An externally braced wing supported using external struts or wires.

Cantilever Wing

A wing supported entirely by internal structures without any external bracing.

Center of Gravity (CG)

The point where the three principal axes of an airplane intersect and around which all aircraft flight rotations occur.

Ailerons

Primary control surfaces located on the trailing edge of wings that rotate the aircraft around the longitudinal axis to control roll.

Elevator

A primary control surface on the trailing edge of the horizontal stabilizer that rotates the aircraft around the lateral axis to control pitch.

Rudder

A primary control surface on the trailing edge of the vertical stabilizer that rotates the aircraft around the vertical axis to control yaw.

Elevon

A single control surface used on tailless aircraft combining the functions of an elevator and an aileron for pitch and roll.

Ruddervator

A control surface on a V-tail aircraft that provides both pitch and yaw movement.

Stabilator

An all-movable tailplane combining horizontal stabilizer and elevator functions to provide longitudinal stability and control.

Trim Tab

A secondary flight control tab set by the pilot to statically balance the aircraft and enable hands-off flight.

Spoilers

Secondary control surfaces on the wing upper surface that decrease lift and assist ailerons in roll control.

Slats

Leading-edge surfaces that extend wing camber to generate greater lift and enable control at low speeds.

Empennage

The complete tail section of an aircraft providing directional and longitudinal stability and control.

Ground Loop

A sudden, uncontrolled rotation of an aircraft on the ground during takeoff or landing operations.

Wheel Well

The stowing compartment into which retractable landing gear retracts during flight.

Firewall

A heat-resistant, stainless steel partition between the engine and cockpit designed to protect occupants from engine fires.

Nacelle

An aerodynamic housing that holds an aircraft engine separately from the fuselage.

Cowling

A removable skin panel on a nacelle providing maintenance access to the engine.

Pylon

A structural member connecting an engine nacelle to the airframe that disrupts jet engine exhaust streams.

ATA 100 Chapters

A standard system developed by IATA to categorize aircraft systems, structures, and maintenance procedures into numbered groups.

Major Zone 100

The aircraft major zoning area designated for the lower half of the fuselage.

Major Zone 200

The aircraft major zoning area designated for the upper half of the fuselage.

Major Zone 300

The aircraft major zoning area designated for the empennage.

Major Zone 400

The aircraft major zoning area designated for powerplants, including struts and pylons.

Major Zone 500

The aircraft major zoning area designated for the left wing.

Major Zone 600

The aircraft major zoning area designated for the right wing.

Major Zone 700

The aircraft major zoning area designated for landing gear and landing gear doors.

Airplane

is a fixed-wing, engine powered aircraft

Glider

is a craft that generates lift by the reaction between its lifting surfaces and the air.

Lighter-than-air

is an aircraft like hot-air balloon, blimp, airship, dirigible, or zeppelin that has no engine.

Powered Lift

is capable of vertical takeoffs and landings as well as long speed flights supported by engine thrust or lift devices.

Powered Parachute

uses a combination of a parafoil and motor to generate lift. It can operate on land or sea

Rotorcraft

generate lift with a spinning rotor or multiple rotors

Weight-Shift-Control (hang glider)

also known as powered hang glider, is a powered aircraft controlled through pilot manipulation of the flexible pivoting wing.

Experimental aircraft category

encompasses a broad range of craft from kit or amateur built unmanned or light sports crafts to research and development or air racing projects.

Light Sport (LSA) aircraft

includes any sport aircraft that does not fit into the gyroplane, kit-built, or designations.

Limited Aircraft

After ultralight they are decommissioned, military aircraft can be modified or converted for civilian use.

Primary aircraft

are manufactured per a production certificate and are flown for pleasure and personal use.

Gyroplane.

Rotors are not engine-driven except for on startup. Rotation is generated by motion usually achieved by conventional propeller propulsion

Helicopter.

Engine-driven rotors for horizontal motion

Stiffener

metal part used in framing of a structure to provide rigidity

SKIS

specialized landing gear attachments that allow airplanes to land, takeoff, and taxi on snow and ice.

FLOATS

also known as pontoons, are elongated, airtight structures attached to the underside of an aircraft to provide buoyancy and enable water landings