Aircraft Structure and Design Overview

Weapon Drop

Firing of weapons not included in sizing analysis.

Specific Fuel Consumption

Fuel consumption rate divided by thrust.

Lift-to-Drag Ratio

Overall aerodynamic efficiency measure of design.

Conceptual Design

Initial phase addressing basic design questions.

Preliminary Design

Phase after major design changes are completed.

Detail Design

Phase where actual parts are fabricated.

Lofting

Mathematical modeling for proper fit of aircraft parts.

Preliminary Weight Estimate

Structural weight is 30-35% of total weight.

Design Take-off Gross Weight

Total aircraft weight at mission start.

Airfoil Thickness Ratio

Maximum thickness divided by chord length.

Mission Fuel

Fuel available for mission performance.

Trapped Fuel

Fuel that cannot be pumped from tanks.

Aerodynamic Center

Point where pitching moment remains constant.

Reynold's Number

Ratio of dynamic to viscous forces in fluid.

Twisting/Washout

Wing design to stall first at the root.

Design Lift Coefficient

Lift coefficient for optimal airfoil performance.

Airfoil Thickness Ratio Effect

Thickness affects wing weight and drag characteristics.

Fat Airfoils

Stall occurs from trailing edge at high angles.

Moderate Thick Airfoils

Flow separates at small angles, causing stalls.

Very Thin Airfoils

Stall occurs at low angles due to flow detachment.

Mean Camber Line

Line equidistant from upper and lower airfoil surfaces.

Thickness Ratio Formula

Thickness ratio calculated as t/c.

Aspect Ratio

Ratio of wingspan to average wing width.

Taper Ratio

Ratio of tip chord to root chord.

Span

Distance from one wingtip to the other.

Airfoil Thickness Ratio

Ratio of airfoil thickness to chord length.

Tip Vortex

Swirling airflow at wing tips causing drag.

Stall Angle of Attack

Angle at which airflow separates, causing loss of lift.

Leading Edge Sweep

Angle of wing leading edge relative to the aircraft.

Induced Drag

Drag caused by lift generation, varies with aspect ratio.

Lift-Curve Slope

Rate of lift increase with angle of attack.

Pitch Attitude

Angle between aircraft's longitudinal axis and horizon.

Wing Weight

Weight of the wing structure, increases with aspect ratio.

Quarter-Chord Line Sweep

Sweep angle measured at quarter chord point of wing.

Oblique Wings

Wings with one swept aft, one swept forward.

Wave Drag

Drag due to shock waves at transonic and supersonic speeds.

Critical Mach Number

Speed at which airflow over wing reaches Mach 1.

Variable Sweep

Wing design allowing adjustment of sweep angle.

Pitch Up

Tendency to uncontrollably increase angle of attack near stall.

Subsonic

Speed less than 0.25 times the speed of sound.

Supersonic

Speed greater than 0.4 times the speed of sound.

Aerodynamic Twist

Adjusts lift distribution to prevent tip stall.

Geometric Twist

Actual change in airfoil angle along the wing.

Dihedral

Angle of wing relative to horizontal plane.

Taper Ratio

Ratio of tip chord to centerline chord.

Wing Incidence

Pitch angle of wing concerning fuselage.

Dutch Roll

Yaw and roll oscillation due to dihedral effect.

Compressibility Drag

Drag increase due to air compressibility effects.

Induced Drag

Drag caused by lift generation.

Tip Stall

Stalling occurring at the wingtip first.

Wing Weight

Weight of the wing structure impacting performance.

Ride through Turbulence

Ability to maintain control during turbulent conditions.

Cockpit Visibility

Pilot's ability to see from the cockpit.

Wing Fuel Volume

Amount of fuel stored in the wing.

Landing Attitude

Aircraft orientation during landing phase.

Spiral Stability

Aircraft's ability to maintain a steady turn.

Ground Clearance

Distance between wing and ground during landing.

Asymmetric Stall

Uneven stalling across the wing span.

Lateral Control at Stall

Control effectiveness during stall conditions.

Wing Size

Influences take-off and landing performance.

Biplane Wings

Two wings stacked for increased lift efficiency.

Wing Loading

Weight supported by wing area affecting performance.

Lift-to-Drag Ratio

Comparison of lift generated to drag experienced.

Span Ratio

Ratio of shorter wing to longer wing.

Wing Tips

Design features affecting aerodynamic efficiency.

Stagger

Longitudinal offset between two wings.

Hoerner Tip

Widely used low-drag wingtip design.

Decalage

Relative incidence angle between two wings.

Monoplane

Aircraft with a single main wing.

Bi-Plane

Aircraft with two stacked wings.

Joined Configuration

Wings connected to improve structural integrity.

Cantilever Wing

Wing supported internally without external bracing.

Braced Wing

Wing supported by external struts or wires.

Plain Flap

Hinged rear section of airfoil for lift.

Split Flap

Hinged bottom surface of airfoil for lift.

Krueger Flap

Leading-edge device increasing effective camber.

Leading Edge Slat

Flap at leading edge enhancing lift.

Single-Slotted Flap

Slot allows airflow to stabilize boundary layer.

Double-Slotted Flap

Higher lift coefficient than single-slotted flap.

Fowler Flap

Tracks to increase wing area and lift.

Empennage

Tail structure for stability and control.

T-Tail

Horizontal tail mounted on vertical tail.

Boom-Mounted Tails

Tails mounted on a boom structure.

V-Tail

Combines vertical and horizontal tail functions.

Inverted V-Tail

Reduces spiraling tendencies in flight.

Control Canard

Forward wing surface for pitch control.

Lifting Canard

Contributes to lift and stability.

Tandem Wing

Two wings positioned one behind the other.

Three Surface Configuration

Includes main wing, canard, and tail.

Back Porch/Aft-Strake

Extension used for pitch control.

Tip Speed

Speed of propeller tips in flight.

Propeller Diameter

Size of propeller affecting performance.

Tractor Configuration

Propeller located forward of the CG.

Pusher Configuration

Propeller located behind the CG.

Conventional Landing Gear

Tail-dragger configuration with rear wheel.

Tricycle Landing Gear

Three-wheel configuration for stability.

Maneuver Loads

Air loads during high maneuvering conditions.

Limit Load

Maximum load anticipated in service.

Design Load

Maximum load structure can support.

Gust Loads

Loads experienced during turbulence.