Aircraft Construction Basics

Overview

This lecture introduces the basics of aircraft construction, including major components, certification standards, and the advantages and disadvantages of different building materials and structures.

Aircraft Categories & Definitions

• Aircraft are devices intended for flight, classified by the FAA under 14 CFR Part 1.
• Categories include airplane, rotorcraft, glider, lighter-than-air, powered lift, powered parachute, and weight shift control.
• "Airplane" is defined as an engine-driven, fixed-wing aircraft supported by air reacting with its wings.
• Advanced avionics aircraft use GPS navigation systems with moving maps and systems like autopilots.

Design, Certification, and Airworthiness

• FAA certifies aircraft, engines, and propellers to specific airworthiness standards in 14 CFR.
• Certification categories include normal, utility, acrobatic, commuter (Part 23), and transport (Part 25).
• Some special classes (e.g., gliders) use mixed standards.
• Type certificates (TC) and data sheets (TCDS) outline approved design/operational details.
• Airworthiness certificates: Standard (white) for most categories, Special (pink) for restricted, experimental, and light sport aircraft.

Basic Aerodynamics & Flight Forces

• Four main forces: thrust (forward), drag (rearward), lift (upward), and weight (downward).
• Aircraft axes: longitudinal (roll), lateral (pitch), and vertical (yaw) pass through the center of gravity (CG).
• CG location affects aircraft stability and must be managed with changes in loading and fuel.

Major Aircraft Components

• Main components: fuselage, wings, empennage (tail group), landing gear, and powerplant.
• Fuselage: central body, connects all parts, holds crew/cargo.
• Wings: main lift surfaces, attached high/mid/low, and have spars, ribs, stringers, fuel tanks, ailerons, and flaps.
• Empennage: includes vertical/horizontal stabilizers, rudder, elevator, trim tabs, and sometimes a stabilator.
• Landing gear: wheels, floats, or skis; types are conventional (tailwheel) or tricycle (nosewheel).
• Powerplant: engine/propeller assembly; engine provides power, electrical, vacuum, and heat; propeller converts engine power to thrust.

Aircraft Construction Types

• Truss structure: tubular framework, not streamlined, originally wood/steel.
• Monocoque: stressed skin bears loads; lightweight but easily damaged.
• Semi-monocoque: skin plus internal framework (bulkheads, stringers) for strength and damage tolerance.
• Firewalls separate engine and cabin for safety.

Composites in Aircraft Construction

• Composites: fiber-reinforced matrices like fiberglass, carbon fiber, or Kevlar.
• Advantages: smooth curves (reduced drag), less corrosion, high strength-to-weight, flexible for rotor blades.
• Disadvantages: hidden damage, complex repairs, water ingress issues, and special considerations for electrical conductivity.
• Composite parts may need metal mesh for lightning protection and adjustments for radio antennas.

Aircraft Subcomponents & Systems

• Airframe: overall structure, supports aerodynamic and operational loads.
• Electrical system: powers instruments, anti-icing, and cabin services via generators, auxiliary power units, or external sources.
• Flight controls: hinged surfaces (ailerons, elevators, rudder) for roll, pitch, and yaw.
• Brakes: disc brakes with caliper pads, designed for high-energy landings.

Control & Navigation Instruments

• Control instruments display attitude and power changes (e.g., attitude indicator).
• Navigation instruments show aircraft position relative to navigation aids.
• Performance instruments measure speed, altitude, etc., via analog/digital displays.

Key Terms & Definitions

• Airworthiness Certificate — FAA document confirming aircraft meets safety and design standards.
• Type Certificate (TC) — Document showing product’s compliance with its design standards.
• Monocoque — Fuselage construction using stressed skin to support structural loads.
• Semi-monocoque — Combines stressed skin with internal framework for support.
• Center of Gravity (CG) — Point where the aircraft’s mass is balanced.
• Empennage — Tail assembly including stabilizers and movable surfaces.
• Composite — Material made from fibers (e.g., carbon, fiberglass) set in a matrix (usually epoxy).
• Stabilator — One-piece, pivoting horizontal stabilizer.

Action Items / Next Steps

• Review Chapter 5 for a detailed explanation of aerodynamics.
• Check the FAA website for additional handbooks on specific aircraft types.
• Read Chapter 9 and 14 CFR Parts 175-225 for further information on airworthiness certificates.