Aircraft Design: A Systems Engineering Approach, M. Sadraey, Wiley, 01 Chapter 11 Aircraft Weight Distribution Tables No Component group Elements Weight X cg Y cg Z cg 1 Wing 1.1. Wing main structure 1.. Ailerons 1.3. Flaps 1.4. Aileron controls 1.5. Flap controls 1.6.Spoilers 1.7. Fairing 1.8. Strut (if any) 1.9. Miscellaneous 1.10. Wing overall Fuselage.1. Fuselage main structure.. Seats.3. Furnishing.4. Doors.5. Windows.6. Fillets.7. Toilets.8. Galleys.9. Stowage.10. Miscellaneous.11. Fuselage overall 3 Empennage 3.1. Horizontal tail 3.. Vertical tail 3.3. Elevator 3.4. Rudder 3.5. Elevator tab 3.6. Rudder tab 3.7. Elevator control 3.8. Rudder control 3.9. Mass balance (if any) 3.10. Empennage overall 4 Powerplant 4.1. Engine 4.. Nacelle 4.3. Pylon 4.4. Propeller 1
4.5. Gear box 4.6. nlet 4.7. Exhaust 4.8. Fuel tanks 4.9. Fuel system 4.10. Oil 4.11. Oil system 4.1. Miscellaneous 4.13. Powerplant overall 5 Landing gear 5.1. Tires 5.. Wheels 5.3. Struts 5.4. Brake system 5.5. Shock absorbers 5.6. Retraction system 5.7. Fairing (if any) 5.8. Wheel control 5.9. Landing gear door 5.10. Landing gear overall 6 Equipment and instruments 6.1. Lights 6.. Batteries 6.3. Auxiliary Power Unit 6.4. Transmitter 6.5. Antenna 6.6. Paint 6.7. Stick/wheel/yoke 6.8. Cockpit instruments panel 6.9. First aid 6.10. Wiring/cable 6.11. Air condition system 6.1. Pedals 6.13. Electric wiring 6.14. Avionic system 6.15. weather radar 6.16. Store 6.17. Pressurization system 6.18. Radome 6.19. Emergency escape hatch 6.0. Hydraulic system 6.1. Fire extinguisher 6.. De-ice system 6.3. Autopilot 6.4. Lightning protection 6.5. Communication system
7 Payload, unpaidload 6.6. NS/RS/GPS/Radio 6.7. Miscellaneous 6.8. Equipment overall 7.1. Flight crew members 7.. Flight attendants 7.3. Passengers 7.4. Technical crew 7.5. Luggage 7.6. Carry-on baggage 7.7. Cargo 7.8. Food, refreshment 7.9. Water 7.10. Fuel 7.11. Load overall Table 11.1. Weight and center of gravity statement 3
No Component Center of gravity location X cg Y cg Z cg 1 Wing 35% - 4% MAC Along FCL 1 5% - 10% thickness above mid-plane Horizontal tail 30% - 40% MAC HT Along FCL Mid-thickness 3 Vertical tail 30% - 40% MAC VT Along FCL 30% - 40% vertical tail span 4 Fuselage 40% - 48% length Along FCL 1% - 5% diameter above FCL 5 Landing gear 15% - 35% wheel base (from main gear) Along FCL 30-40% of the gear height from ground 6 Turbine engine 30% - 45% engine length from inlet Along shaft Along the shaft centerline 7 Piston engine Treat it as a rectangular prism 8 Human while seating See Chapter 7 Along midplane See Chapter 7 Table 11.. Center of gravity locations for various non-homogenous components 1 Fuselage Center Line n the case where the seating arrangement is not symmetric, the cg is shifted toward the side with more seats. 4
No Criterion Forward cg Aft cg 1 Stability Aircraft is longitudinally/directionally more stable stable Controllability Aircraft is longitudinally/directionally less controllable 3 Elevator design Aircraft requires greater elevator deflection during take-off rotation 4 Rudder design Aircraft requires more rudder deflection during asymmetric thrust 5 Load on wheel There will be more load on the nose wheel (in a tricycle configuration) Aircraft is longitudinally/directionally less Aircraft is longitudinally/directionally more controllable Aircraft requires smaller elevator deflection during take-off rotation Aircraft requires smaller rudder deflection during asymmetric thrust There will be more load on the main wheel (in a tricycle configuration) 6 Taxi t is easier for aircraft to turn during taxi t is harder for aircraft to turn during taxi 7 Fuel cost Cruising flight will often burn more fuel Cruising flight will often burn less fuel 8 Stall Aircraft is safer (to enter stall) Aircraft is more prone to stall 9 Spin Aircraft is safer (to enter spin) Aircraft is more prone to spin 10 Spin recovery Recovery is slower (if aircraft is spinnable) Recovery is faster (if aircraft is spinnable) 11 Crash Aircraft is safer and there is less Aircraft is more prone to crash possibility of crash 1 Mishap Aircraft is safer during taxi Aircraft is prone to tip back during take-off 13 Gust t takes more oscillations to recover when a gust hits and disturbs the longitudinal trim. t takes fewer oscillations to recover when a gust hits and disturbs the longitudinal trim. Table 11.3. Features of forward and aft cg positions 5
No Criterion Wider cg range Shorter cg range 1 Load handling Aircraft can carry more diverse Aircraft can carry less diverse (customer) combinations of load/cargo (in combinations of load/cargo (both size terms of both size and volume) Accident/crash Aircraft is less prone to accident/crash due to loading issues and volume) Aircraft is more prone to accident/crash due to loading issues 3 Configuration design Aircraft configuration design is more challenging Aircraft configuration design is less challenging 4 Alternatives There are less aircraft configuration alternatives There are more aircraft configuration alternatives Table 11.4. Features of cg range 6
No Aircraft Engine m TO (kg) Forward cg Aft cg CG Range 1 Cessna 17 Single Piston 1,111 15.6 36.5 0.9 Cessna 177-Utility Single Piston 1,100 5 18.5 13.5 3 Cessna 06 Skywagon Single Piston 1,63 1. 39.4 7. 4 Cessna Skymaster Twin piston,000 17.3 30.9 13.6 5 Air Tractor AT-60 Single turboprop 7,57 3 35 1 6 Piper PA-30 Comanche Twin piston 1,690 1 7.8 15.8 7 Beechcraft Queen Air Twin piston 3,99 16 9.3 13.3 8 Dornier Do 8 Twin piston,70 10.7 30.8 0.1 9 Douglas DC-6 Four radial 44,19 1 35 3 10 Pilatus PC-1 Single turboprop 4,740 13 46 33 11 Beechcraft B-45 Single turboprop 1,950 19 8 9 1 Pilatus PC-6 Single turboprop 6,108 11 34 3 13 Fokker F-7 Twin turboprop 19,773 18.7 40.7 14 Lockheed C-130E Four turboprop 70,300 15 30 15 15 Learjet 5 Twin turbojet 6,80 9 30 1 16 Gulfstream G00 Twin turbofan 16,080 40 18 17 Cessna Citation Twin turbofan 9,57 14 31 17 18 Fokker F-8 Twin turbofan 9,000 17 37 0 19 DC-9-10 Twin turbofan 41,100 15 40 5 0 Gulfstream G550 Twin turbofan 41,77 1 45 4 1 Boeing 737-100 Twin turbofan 50,300 11 31 0 Boeing 707-10 Four turbofan 116,570 16 34 18 3 Boeing 747-00 Four turbofan 377,84 1.5 3 19.5 4 Douglas DC-8 Four turbofan 140,600 16.5 3 15.5 5 Lockheed C-141 Four turbofan 147,000 19 3 13 6 Lockheed C-5A Four turbofan 381,000 19 41 7 Concorde Four turbojet 185,700 0 59 39 Table 11.5. Aft cg, forward cg and cg range for several aircraft in terms of percent MAC 7
No Aircraft/wing Configuration Wing/fuselage ac (% MAC) Muck shift (percent MAC) 1 Wing alone Lifting surface 5 0 Cessna 17 Single-engine light GA 1-4 3 Learjet 4 Six-seat twin-jet engine 11-14 4 Piaggio P-180 Nine-seat twin-turboprop pusher -7-3 Table 11.6. Position of the wing-fuselage combination aerodynamic center for several aircraft 8
No Component Mass (kg) X cg (m) 1 Wing 4,00 13 Tails 600 4 3 Engine 6,900 17 4 Fuselage 3,300 13 5 Pilots + bag (80+10) 3.6 6 Passengers (first row) 80 8 7 Flight attendant 80+10 5 8 Carry-on baggage (first row) 10 8 9 Checked baggage 600 15 10 Landing gear 1,00 9 11 Wing fuel 3,050 13 1 Fuselage fuel 6000 9 13 Systems and other equipment,800 8 Table 11.7. Mass and cg locations (X cg ) of major components for aircraft in Example 11. Component X cg (m) Location Pilots 3.6 Ahead of Xcg 1 Flight attendant 5 Ahead of Xcg 1 Passengers +carry-on bag (first row) 8 Ahead of Xcg 1 Fuselage fuel 9 Ahead of Xcg 1 Passengers +carry-on bag (second row) 9 Ahead of Xcg 1 Passengers +carry-on bag (third row) 10 Ahead of Xcg 1 Passengers +carry-on bag (fourth row) 11 Ahead of Xcg 1 Passengers +carry-on bag (fifth row) 1 Ahead of Xcg 1 Aircraft (with maximum take-off weight) 1.843 Xcg 1 Passengers +carry-on bag (sixth row) 13 Aft of Xcg 1 Wing fuel 14 Aft of Xcg 1 Checked baggage 15 Aft of Xcg 1 Table 11.8. Removable components and their locations compared with aircraft cg at maximum take-off weight 9
No Aircraft Forward cg (% MAC) Aft cg (% MAC) CG range (% MAC) 1 GA-subsonic 15-0 5-30 5-15 Subsonic transport 5-0 0-35 10-30 3 Supersonic transport 15-35 40-60 0-40 4 Fighter subsonic speeds 15-0 35-45 15-30 5 Fighter supersonic speeds 45-50 50-55 10-30 Table 11.9. Recommended longitudinal cg locations for various aircraft 10
Level Category A and C flight phase Category B flight phase Level 1 0.35 < sp < 1.3 0.3 < sp <.0 Level 0.5 < sp <.0 0. < sp <.0 Level 3 0.15 < sp 0.15 < sp Table 11.10. Short period damping ratio limits [5] 11
No Aircraft component 1 Wing, Horizontal tail, Vertical tail Component model Rectangular prism or thin plate of Thickness t, Length b, Chord C Fuselage Thin cylindrical shell of radius r 3 Engine Solid Cylinder of radius r, length L 4 Propeller Slender rod of length L Geometry, Axis Mass moment of inertia z 1 xx m b t 1 cg 1 yy m t C 1 y x 1 zz m b C 1 and length L x m 6r L x x z z z cg cg cg y y y xx yy zz xx yy zz xx yy zz mr 1 m 6r 1 1 mr 1 m 3r 1 1 m 3r 1 0 1 ml 1 1 ml 1 L L L 5 Human pilot; Passenger; Seat; Fuel tank; Miscellaneous items Point mass of mass m x r 1 r z y r 3 xx yy zz mr mr r 1 1 mr 3 r Table 11.11. Mass moment of inertia of aircraft components [11 and [1] 1
No Aircraft m TO (kg) xx (kg.m ) yy (kg.m ) zz (kg.m ) xz (kg.m ) 1 Cessna 18 1,00 1,85 1,85,667 0 Beech 99 4,990 0,593 7,455 46,90 5,96 3 Cessna 60 6,800 87,87 3,455 87,508 0 4 McDonnell F-4 15,100 3,13 159,300 181,300 170 5 Boeing 747-00 88,500 4,675,886 44,877,574 67,384,15 1,315,143 Table 11.1. Body-axis mass moments of inertia for several aircraft No Component Mass (kg) Symbol X cg (m) 1 Engine 0 m e 1.8 Fuselage 30 m b 4.6 3 Pilot 1 90 m P1 3.6 4 Pilot 90 m P 4.8 5 Landing 130 m lg 3.5 gear 6 Tails 70 m t 8.5 7 Systems 655 m s 4.1 8 Wing 375 m w X1 9 Fuel 550 m f X Table 11.13. Mass and cg locations of various components of the aircraft in Example 11.5 13
No Component X cg (m) 1 Engine 1.8 Aircraft 3.451 Landing gear 3.5 3 Fuel 3.597 4 Pilot 1 3.6 5 Wing 3.91 6 Systems 4.1 7 Fuselage 4.6 8 Pilot 4.8 9 Tails 8.5 Table 11.14. The cg of components in Example 11.5 14
No Component Mass (kg) Symbol X cg (m) 1 Engine 0 m e 1.75 Fuselage 300 m b 4.3 3 Pilot 1 80 m P1 3.4 4 Pilot 80 m P 4.5 5 Landing 130 m lg 3.3 gear 6 Tails 70 m t 7.4 7 Systems 630 m s 4 8 Wing 360 m w x w 9 Fuel 50 m f x f Table 11.15. Mass and cg locations of various components of the aircraft in Problem 1 15
No Component Mass X cg (from fuselage nose) Feautures 1 Fuselage 1% of m TO 41% of L f L f = 15 m, D f = 1.6 m Wing 14% of m TO Unknown for designer AR = 9, = 1, LE = 0 3 Horizontal tail 4% of m TO 91% of L f AR = 5, = 1, LE = 0 4 Vertical tail % of m TO 93% of L f AR =.5, = 1, LE = 30 deg 5 Engine 18% of m TO 63% of L f twin-engine beside fuselage 6 Landing gear 5% of m TO Xcg_main = 48% of L f Xcg_nose = 10% of L f Tricycle configuration W mainlg = 4% of m TO 7 Fuel 1,550 kg 58% of L f n three fuel tanks 8 Passengers 10 85 kg Xcg_front_row = 15% of Two seats in each row L f Xcg_ last_row = 50% of L f 9 Luggage 10 30 kg 64% of L f n rear fuselage 10 Pilot 100 kg 10% of L f one 11 Other systems 5% of m TO 50% of L f - Table 11.16. Mass and cg locations of various components of the aircraft in Problem 16
No Component Mass (kg) X cg (m) 1 Wing 000 9.5 Tails 400 18 3 Engine 400 7.7 4 Fuselage 1600 9.3 5 Pilots + bag 00 3. 6 Passengers (first row) 3 85 4.5 7 Flight attendant 100 15.7 8 Carry-on baggage (first row) 3 15 4.5 9 Checked baggage 34 40 15 10 Landing gear 800 6.8 11 Wing fuel 1,000 8.6 1 Fuselage fuel,000 6.4 13 Systems and other equipment 7,000 9 Table 11.17. Mass and cg location (X cg ) of major components for aircraft in Problem 3 17