Assembly & Rigging – Fixed- and Rotary-Wing Fundamentals
Page 1
• Course reference: AERM-2233, Chapter 1 (pp. 1-24 → 1-32) & Chapter 2 (pp. 2-1 → 2-69).
• Core objectives
• Rig fixed-wing aircraft (aileron, elevator, rudder, flaps)
• Assemble primary/secondary airframe components
• Verify structural alignment & symmetry
• Balance flight-control surfaces
• Rig rotary-wing aircraft (collective, cyclic, anti-torque)
Page 2
• Graphic: Main airplane parts identified—Propeller, Wing, Fuselage, Ailerons, Elevator, Rudder, Flaps.
• Baseline nomenclature for subsequent rigging tasks.
Page 3
• Two fundamental sources of lift
• Aerostatic (lighter-than-air)
• Aerodynamic (due to motion through air)
• International Standard Atmosphere (ISA) at MSL
• Pressure ≈ 29.92\,\text{in Hg} = 14.69\,\text{psi} =1013.2\,\text{mbar}
• Temperature ≈ 59\,^{\circ}!F=15\,^{\circ}!C
• Humidity = water-vapor content; affects density & instrument calibration.
Page 4
• Four primary forces in steady flight (Fig 2-7):
• Thrust (+x)
• Drag (−x)
• Lift (+z)
• Weight (−z)
• Rigging must preserve correct vector relationships under varying load/CG.
Page 5
• Bernoulli Principle for sub-sonic flow:
P+\tfrac12\rho V^2 = \text{constant}
• Constriction ⇒ ↑velocity, ↓static pressure—foundation for wing lift & venturi instruments.
Page 6
• Fig 3-3 shows pressure/velocity exchange along airfoil.
• Key takeaway: Lower surface high-pressure; upper-surface low-pressure yields net upward force.
Page 7 & 8
• Cambered airfoil behaves like venturi throat; curvature accelerates flow over top surface.
• Diagram A (tube) vs. Diagram B (wing) analogy.
Page 9
• Upwash → Low-pressure peak migrates aft toward center of lift.
• Downwash balances moment about CP (center of pressure).
• Vector diagram emphasizes high-pressure underside, low-pressure topside.
Page 10
• Sample pressure/velocity data points across chord:
• LE stagnation: 100\,\text{mph},\,14.7\,\text{psi}
• Upper surface peak: 115\,\text{mph},\,14.54\,\text{psi}
• Illustrates ΔP→ΔV relationship.
Page 11
• Airfoil definition: Any structure that converts aerodynamic reaction into lift; includes wings, stabilizers, rotor blades, propellers & some fuselage sections.
Page 12–14
• Fineness ratio = chord ÷ max thickness.
• High ratio → lots of skin-friction drag; low ratio → form-turbulence drag.
• Optimum L/D occurs at specific angle-of-attack (AOA).
• Increased camber ⇒ ↑max C_L but shifts CP forward; must be balanced in rigging.
Page 15–17
• Upper camber, lower camber, mean camber definitions.
• Aspect ratio =\tfrac{\text{span}}{\text{average chord}}; higher AR increases lift and lowers induced drag.
Page 18–19
• Structural layout: leading edge, front spar, main spar, rear spar, ribs, flaps.
• Fuel often stored in integral torsion-box wing.
Page 20
• Angle of attack (AOA) = acute angle between chord line & relative wind.
• Center of pressure (CP) migrates with AOA; drag component grows proportional to C_D.
Page 21
• Stall progression: boundary-layer separation starts near trailing edge and moves forward as AOA increases beyond \alpha_{\text{critical}}.
Page 22
• Flap deployment increases wing camber & effective AOA at same pitch attitude ⇒ lower stall speed, steeper approach.
Page 23–24
• Angle of incidence = fixed angle between chord & longitudinal axis; set during manufacture.
• Canard aircraft: Canard at higher incidence supplies ≈20 % lift; stalls first, producing nose-down recovery moment.
Page 25–26
• Review questions reinforce terminology (AOA, chord, aspect ratio).
• Dihedral board + bubble level used to verify wing dihedral across front spar.
• Buttock line = lateral reference from aircraft centerline; fuselage stations provide longitudinal reference.
Page 27–33 (Drag taxonomy)
• Induced drag \propto\tfrac{L^2}{\pi e AR q} increases with AOA.
• Parasite drag components: form, skin-friction, interference; grows with V^2.
• Total drag curve has minimum at V_{\text{L/D max}}.
Page 34–46 (Axes & Controls)
• Three axes: longitudinal (roll), lateral (pitch), vertical (yaw).
• Ailerons: differential deflection mitigates adverse yaw.
• Elevator/stabilator: longitudinal control; anti-servo tabs add feel.
• Rudder: yaw control; often interconnected springs for coordinated turns.
• Stability types: static vs. dynamic; positive, neutral, negative.
• Longitudinal stability aided by CG forward of CP.
• Control system schematic: yoke→cables→pulleys→bellcranks→surfaces.
Page 47–65 (Lateral/Directional stability, wing-tip vortices)
• Dihedral, sweep, and keel effect improve roll stability.
• Directional stability from vertical fin; proper rigging aligns fin parallel to vertical but can be offset from longitudinal axis to counter propeller slipstream.
• Vortex generators energize boundary layer on high-speed wings.
• Wing-tip dihedral (≈25° over outboard 60 % span) diminishes vortex downwash.
Page 66 (High-speed airfoil & Mach effects)
• Critical Mach (M_{crit}) when local flow reaches M=1 before free-stream does.
• Normal shock waves cause separation & buffet; supercritical & swept wings delay shocks.
Page 67–76 (Primary control systems & tabs)
• Figures illustrate cable-operated ailerons, rudder, elevator; differential movement; trim, balance, servo, and anti-servo tabs.
• Trim tabs allow hands-off flight; balance tabs reduce control force; servo tabs move primary surface via aerodynamic force; anti-servo tab increases stick force on stabilator.
Page 77–83 (Flap types & leading-edge devices)
• Plain, split, slotted, Fowler, double/triple-slotted flaps—each increases CL; Fowler adds chord. • LE devices: droop nose, Kruger flap, automatic/controllable slats; extend \alpha{\text{stall}}.
• Slots duct high-energy air to delay separation.
Page 84–92 (Advanced empennage & stabilizer trim)
• Aerodynamic balance horns, jackscrew-actuated variable incidence stabilizer.
• Down-spring prevents deep stall with aft CG.
• Antiservo tab on stabilator provides pitch stability & trim.
Page 93–115 (Control-cable hardware & maintenance)
• Cable construction: 1×7, 1×19 (non-flex), 7×7 (flex), 7×19 (extra flex).
• Terminations: Nicopress thimble-eye splice, swaged terminals (AN663-667).
• Fairleads, pulleys, guards—prevent chafing & mis-routing.
• Tensiometer usage; temperature correction via rig-load charts.
• Turnbuckle assembly & safety-wiring patterns; clip-type locks; min 4 wrap turns.
• Typical safety-wire sizes (e.g., 0.040\,\text{in} brass or stainless).
Page 116–131 (Measurement of control travel & symmetry)
• Rudder/aileron deflection measured with templates, protractors, or wire pointers.
• Push-pull rods & torque tubes: check rod-end bearing self-alignment & safety wire.
• Incidence & dihedral checked with incidence/dihedral boards + spirit levels.
• Symmetry cross-measurements using 50-ft steel tape between datum points; allowable tolerance per MM.
• Eccentric bushings allow fine incidence adjustment on some cantilever wings.
Page 132–138 (Pre-rig inspection & locking controls)
• Verify manuals (TCDS, TM, CMM, MM).
• Examine for safety, security, wear, corrosion, lubrication pre-/post-rig.
• Rigging pins, pedal blocks, straightedge clamps center controls during tension adjustment.
Page 139–144 (Control-surface balancing)
• Balance fixture aligns hinge line; move weight until surface neutrally balanced.
• Documentation of over/under-balance per MM; weight installed only on approved lugs.
Page 144–148 (Aircraft jacking procedure)
• Review MM; clear area; verify jack condition; use proper jack points; tail-weight if required.
• Raise/lower gradually & symmetrically; confirm gear extension; wiggle wings when lowering to seat oleos.
Page 149 (—blank—)
Page 150–159 (Helicopter flight-control systems)
• Collective: twist-grip throttle integrates RPM with blade pitch. Raising collective sleeve increases uniform blade pitch (Fig 4-55).
• Cyclic: tilts swashplate; decreases pitch on advancing blade & increases on retreating blade (gyroscopic precession ⇒ disc tilts).
• Tail-rotor/anti-torque pedals adjust tail-rotor pitch via cables, pulleys, turnbuckles.
• NOTAR system uses main-rotor downwash & lateral jet to counter torque.
Page 160–166 (Rotor types & freewheeling)
• Rotor hinges:
• Fully articulated—flap, drag, feather.
• Semirigid—teetering flaps as a unit.
• Rigid—only feathering.
• Sprag freewheeling clutch disengages engine during autorotation.
• Blade tracking methods: cloth flag, strobe, electronic analyzer (Chadwick-Helmuth 8500C).
Page 167 (—blank—)
Page 168–173 (—blank—)
Page 174–185 (Rotorcraft aerodynamics)
• Helicopter components overview (Fig 1-1).
• Rotor head: flapping, drag, feather hinges.
• Anti-torque systems: tail rotor, Fenestron, Coandă jet.
• Force equilibrium in hover; coning due to lift-centrifugal balance.
• Vectoring thrust forward with cyclic causes translation.
• Dissymmetry of lift—advancing blade faster; cyclic pitch corrections equalize lift (Fig 2-125).
Page 186–188
• Autorotation vs. powered flight (Fig 3-20).
• Control axes: rotor disc tilts for roll & pitch; antitorque for yaw; similar to fixed-wing axes but control inputs differ.