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weight and performance calculations for the Douglas DC-8-20
United Airlines DC-8-21 N8026U c/n 45295 Los Angeles (LAX), April 1977
Douglas DC-8-20
role : jet airliner
importance : ****
first flight : 29 November 1958 operational : January 1960
country : United States of America
design :
production : DC-8-21 : 33 aircraft, total DC-8 : 556 aircraft
general information :
Version for domestic transportation in the U.S.
Higher-powered 15,800 lb (70.8 kN) thrust Pratt & Whitney JT4A -3 turbojets (without
water injection) allowed a weight increase to 276,000 pounds (125,190 kg) and improved
hot & high performance. 33 DC-8-20s were built plus 16 converted DC-8-10s.
This model was originally named "DC-8B" but was renamed when the series 30 was
introduced.
Has a larger fuel capacity : 66528 litres.
Wing area early aircraft : 257.6 m2, with extended leading edge : 266.5 m2
primary users : : United (15), Eastern (15), National Air Lines (3)
Accommodation:
flight crew : 4 cabin crew : 5
flight crew consist of pilot, co-pilot, navigator and flight engineer
passengers : seating for 132 in two class : 16 business class and 116 coach class seats ( 34 -in pitch) high density seating for 179 passengers
engine : 4 Pratt & Whitney JT4A-3 turbojet engines of 70.31 [KN] (15806.1 [lbf])
dimensions :
wingspan : 43.41 [m], length : 45.87 [m], height : 12.91 [m]
wing area : 266.5 [m^2] fuselage exterior width : 3.73 [m]
weights :
empty weight : 53000 [kg]
operating empty weight : 56175 [kg] max. structural payload : 19800 [kg]
Zero Fuel weight (ZFW) : 75975 [kg] max. landing weight (MLW) : 90500 [kg]
max.take-off weight : 125192 [kg] weight fuel : 53222 [kg] (66528 [litres])
performance :
Max. operating Mach number (Mmo) : 0.84 [Mach] (932 [km/hr]) at 7620 [m]
max. cruising speed : 873 [km/hr] (Mach 0.81 ) at 9950 [m] (39 [%] power)
economic cruising speed : 865 [km/hr] (Mach 0.80 ) at 9950 [m]
service ceiling : 12000 [m]
range with max fuel and Max.TOW : 6850 [km] (ATA domestic fuel reserves - 370.0 [km] alternate)
description :
cantilever low-wing monoplane with retractable landing gear with nose wheel
Wings : two main spar fail-safe wing structure with double slotted trailing edge flaps with leading edge slots ,with spoilers airfoil : NACA sweep angle 3/4 chord: 30.9 [°]
engines attached with pylons to the wing, main landing gear attached to the wings, fuel tanks in the wings and fuselage
Fuselage : Pressurized conventional all-metal fail safe structure with double-bubble cross section
calculation : *1* (dimensions)
wing chord at root : 9.67 [m]
wing chord at tip : 2.22 [m]
taper ratio : 0.230 [ ]
mean wing chord : 6.14 [m]
calculated average wing chord tapered wing with rounded tips: 6.11 [m]
wing aspect ratio : 7.07 []
Oswald factor (e): 0.685 []
seize (span*length*height) : 25707 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 11.2 [kg/hr]
fuel consumption (econ. cruise speed) : 6376.4 [kg/hr] (7970.5 [litre/hr]) at 29 [%] power
distance flown for 1 kg fuel : 0.14 [km/kg] at 9950 [m] height, sfc : 78.0 [kg/KN/h]
total fuel capacity : 66528 [litre] (53222 [kg])
calculation : *3* (weight)
weight engine(s) dry : 8400.0 [kg] = 29.87 [kg/KN]
weight 131 litre oil tank : 11.17 [kg]
oil tank filled with 1.8 litre oil : 1.6 [kg]
oil in engine 3.4 litre oil : 3.1 [kg]
fuel in engine 15.3 litre fuel : 11.25 [kg]
weight fuel lines 143.5 [kg]
DC-8-21 N8606 photographed in 1964, note the extended ejector rings at the back of the engines
weight ejector rings : 140 [kg]
weight engine cowling 731.2 [kg]
total weight propulsion system : 9442 [kg](7.4 [%])
***************************************************************
Accommodation cabin facilities:
typical 2-class cabin layout for 132 passengers : economy : pitch : 86.4 [cm] 34.0 [-in] ( 3+3 ) seating in 22.5 rows
weight seats : 705.0 [kg]
high density seating passengers : 179 [pax] at 6 -abreast seating in 29.8 rows, pitch 86.4 [cm] 34.0 [-in] 
Interior of Eastern Airlines DC-8-21
pax density, normal seating : 0.73 [m2/pax], high density seating : 0.53 [m2/pax]
weight 4 lavatories : 58.0 [kg]
weight ladies’ powder room : 16 [kg]
weight men’s dressing room : 12 [kg]
weight diplomatic mail locker : 2 [kg]
weight lounge : 35 [kg]
weight 4 buffets : 121.8 [kg]
weight overhead stowage for hand luggage : 46.2 [kg]
weight 3 wardrobe closets : 26.4 [kg]
weight 3 movie screens : 21.1 [kg]
weight 47 windows : 42.4 [kg]
weight 2 (1.83 x 0.88 [m]) main entry doors : 113.6 [kg]
weight 2 (1.63 x 0.85 [m]) service doors : 98.2 [kg]
weight 2 (122x91 cm) freight doors (belly) : 62.9 [kg]
total belly baggage/cargo hold volume : 39.13 [m3]
cabin volume (usable), excluding flight deck : 216 [m3]
passenger compartment volume : 146 [m3]
passenger cabin max.width : 3.51 [m] cabin length : 31.08 [m] cabin height : 2.21 [m]
floor area : 95.7 [m2]
weight cabin facilities : 1333.6 [kg]
safety facilities:
weight 4 type III over wing emergency exits (51x91 cm): 69.5 [kg]
evacuation time with 179 passengers : 45 [sec]
weight 7 hand fire extinguisher : 20 [kg]
weight oxygen masks & oxygen generators : 85.8 [kg]
weight emergency flare installation : 10 [kg]
weight 4 emergency evacuation slides : 111.9 [kg]
weight safety equipment & facilities : 297 [kg]
fuselage construction:
fuselage aluminium frame : 11301 [kg]
floor loading (payload/m2): 207 [kg/m2]
weight rear pressure bulkhead : 188.8 [kg]
fuselage covering ( 366.4 [m2] duraluminium 3.28 [mm]) : 3170.9 [kg]
weight floor beams : 617.0 [kg]
weight cabin furbishing : 844.3 [kg]
weight cabin floor : 1455.6 [kg]
weight (sound proof) isolation : 310.1 [kg]
weight 34844 [litre] main central fuel tanks empty : 1951.3 [kg]
weight empty 118 [litre] potable water tank : 10.5 [kg]
weight empty waste tank : 11.3 [kg]
weight fuselage structure : 19860.5 [kg]
Avionics:
weight radio transceiver equipment : 7.0 [kg]
weight dual cloud-collision radar : 25.0 [kg]
weight Doppler & radio direction finding (RDF) equipment : 5.0 [kg]
weight Sperry automatic flight control system, with SP-30 auto-pilot : 25.0 [kg]
weight artificial horizons, compass, alti-meters : 7 [kg]
weight engine monitoring gauges & control switches : 12 [kg]
weight avionics : 87.0 [kg]
cockpit of DC-8-21 TC-JDV c/n 45429 van Bursa Airlines
Systems:
Air-conditioning and pressurization system maintains sea level conditions up to 7100 [m]
and gives equivalent of 2000 [m] at 12200 [m]. pressure differential : 0.62 [bars] (kg/cm2)
pressurized fuselage volume : 394 [m3]
weight air-conditioning and pressurization system : 202 [kg]
weight APU / engine starter: 35.2 [kg]
weight lighting : 43.6 [kg]
weight 210 bar hydraulic system : 85.7 [kg]
weight engine-driven 40kVA electricity generators : 33.0 [kg]
weight 22Ah battery : 12.0 [kg]
weight controls : 19.8 [kg]
weight systems : 431.5 [kg]
total weight fuselage : 22010 [kg](17.6 [%])
***************************************************************
average Take-off weight : 94977 [kg](75.9 [%])
total weight aluminium ribs (916 ribs) : 3926 [kg]
weight engine mounts : 141 [kg]
weight 6 wing fuel tanks empty for total 31684 [litre] fuel : 1774 [kg]
weight wing covering (painted aluminium 2.82 [mm]) : 4060 [kg]
total weight aluminium spars (multi-cellular wing structure) : 4275 [kg]
weight wings : 12261 [kg]
weight wing/square meter : 46.01 [kg]
weight thermal leading-edge anti-icing : 47.8 [kg]
weight ailerons (11.24 [m2]) : 259.5 [kg]
weight fin (30.49 [m2]) : 703.6 [kg]
weight rudder (9.49 [m2]) : 210.2 [kg]
weight tailplane (stabilizer) (52.52 [m2]): 1333.3 [kg]
weight elevators (11.36 [m2]): 141.57 [kg]
weight flight control hydraulic servo actuators: 42.8 [kg]
United N8025U c/n 45294, Chicago, O’ Hare apt., October 1974
weight trailing-edge double slotted flaps (43.01 [m2]) : 846.0 [kg]
weight leading edge slots (1.89 [m2]) : 27.2 [kg]
weight spoilers (12.6 [m2]) : 146.6 [kg]
total weight wing construction : 17934 [kg] (31.9 [%])
*******************************************************************
tire pressure main wheels : 9.21 [Bar] (nitrogen), ply rating : 21 PR
tire speed limit : 364 [km/hr]
total tyre footprint : 0.64 [m2]
Aircraft Classification Number, MTOW on rigid runway and medium subgrade strength (B) : 26 [ ]
DC-8-21 N8014U van United
Can also operate from unpaved runways subgrade B
wheel pressure : 13771.1 [kg]
weight 8 Dunlop main wheels (1130 [mm] by 420 [mm]) : 827.0 [kg]
weight 2 nose wheels : 103.4 [kg]
weight multi-disc wheel-brakes : 76.0 [kg]
weight Hydro-air flywheel detector type anti-skid units : 9.0 [kg]
weight oleo-pneumatic shock absorbers : 101.3 [kg]
weight wheel hydraulic operated retraction system : 1131.1 [kg]
weight undercarriage struts (four-wheel bogies) with axle 3351.2 [kg]
total weight landing gear : 5599.0 [kg] (4.5 [%]
*******************************************************************
********************************************************************
calculated empty weight : 54845 [kg](43.8 [%])
weight oil for 9.4 hours flying : 112.7 [kg]
weight lifejackets : 59.4 [kg]
weight 2 life rafts : 82.5 [kg]
weight catering : 130.7 [kg]
weight water : 104.5 [kg]
weight crew : 729 [kg]
weight crew lugage,nav.chards,flight doc.,miscell.items : 111 [kg]
operational weight empty : 56175 [kg] (44.9 [%])
********************************************************************
weight 132 passengers : 10164 [kg]
weight luggage : 2112 [kg]
weight cargo : 7524 [kg] (cargo+luggage/m3 belly : 233 [kg/m3])
zero fuel weight (ZFW): 75975 [kg](60.7 [%])
weight fuel for landing (2.3 hours flying) : 14525 [kg]
max. landing weight (MLW): 90500 [kg](72.3 [%])
max. fuel weight : 109397 [kg] (87.4 [%])
payload with max fuel : 170 passengers+luggage 15795 [kg]
published maximum take-off weight : 125192 [kg] (100.0 [%])
calculation : * 4 * (engine power)
power loading (Take-off) : 445 [kg/KN]
power loading (Take-off) 1 PUF: 594 [kg/KN]
max. total take-off power : 281.2 [KN]
calculation : *5* (loads)
manoeuvre load : 8.4 [g] at 1000 [m]
limit load : 2.5 [g] ultimate load : 3.8 [g] load factor : 1.1 [g]
design flight time : 1.98 [hours]
design cycles : 15800 sorties, design hours : 31284 [hours]
max. wing loading (MTOW & flaps retracted) : 470 [kg/m2]
wing stress (2 g) during operation : 172 [N/kg] at 2g emergency manoeuvre
calculation : *6* (angles of attack)
angle of attack zero lift : -1.81 ["]
max. angle of attack (stalling angle, clean) : 13.49 ["]
max. angle of attack (full flaps) : 12.95 ["]
angle of attack at max. speed : 0.79 ["]
calculation : *7* (lift & drag ratios
lift coefficient at angle of attack 0° : 0.15 [ ]
lift coefficient at max. speed : 0.22 [ ]
lift coefficient at max. angle of attack : 1.27 [ ]
max. lift coefficient full flaps : 1.62 [ ]
drag coefficient at max. speed : 0.0226 [ ]
drag coefficient at econ. cruise speed : 0.0256 [ ]
induced drag coefficient at econ. cruise speed : 0.0060 [ ]
drag coefficient (zero lift) : 0.0196 [ ]
lift/drag ratio at max. speed : 9.53 [ ]
calculation : *8* (speeds
take-off safety speed (V2) : 252 [km/u]
take-off (initial climb) speed (Vto) : 302 [km/u]
stalling speed clean at sea-level (OW loaded : 118816 [kg]): 270 [km/u]
max. rate of climb speed : 530 [km/hr] at sea-level
max. endurance speed (Vbe): 497 [km/u] min. fuel/hr : 5408 [kg/hr] at height : 5486 [m]
max. range speed (Vbr): 922 [km/u] min. fuel consumption : 6.775 [kg/km] at cruise height : 11278 [m]
cruising speed : 873 [km/hr] at 9950 [m] (power:29 [%])
max. operational speed (Mmo) : 932 [km/hr] (Mach 0.84 ) at 7620 [m] (power:38.6 [%])
airflow at cruise speed per engine : 94.0 [kg/s]
speed of thrust jet : 1664 [km/hr]
initial descent speed 10000 - 7315 [m]: Mach 0.75
descent speed 7315 - 3048 [m]: 537 [km/u]
approach speed 3048 - 500 [m] (clean): 463 [km/u]
stalling speed clean at 500 [m] height at Max.Landing Weight : 90500 [kg]): 241 [km/u]
final approach speed at sea-level with full flaps (normal landing weight) (Vapp): 251 [km/u]
ICAO Aircraft Approach Category (APC) : C
landing speed at sea-level (normal landing weight(Vtd): 90382 [kg]): 238 [km/hr]
stalling speed at sea-level with full flaps (max. landing weight): 193 [km/u]
rate of climb at sea-level ROC (loaded, 66 % power) : 808 [m/min]
rate of climb at sea-level ROC (loaded, 75% power) : 1015 [m/min]
rate of climb at 1000 [m] with 1 engine out (PUF/MTOW, 100 % power on remaining engines) : 826 [m/min]
rate of climb at 1000 [m] with 2 engines out (2xPUF / MTOW) : 278 [m/min]
max.rate of descent with landing gear extended, with use of spoilers: 457 [m/min]
calculation : *9* (regarding various performances)
low wheel pressure, can also take off from unpaved runways
take-off distance at sea-level concrete runway : 2417 [m]
take-off distance at sea-level gravel/packed earth field : 3448 [m]
ICAO Aerodrome Reference Code : 4D
take-off distance (C.A.R) at sea-level over 10.7 [m] height : 2534 [m]
FAR TO runway length requirement at MTOW, standard day at SL (ASDA): 2511 [m]
landing distance (MLW) : 808 [m]
landing distance (C.A.R.) from 15 [m] at SL, dry runway : 2080 [m]
landing distance (C.A.R.) from 15 [m] at SL, wet runway : 2380 [m]
Overseas National Airways DC-8-21 N819F c/n 45437, Vienna, Austria 1975
FAR landing runway length requirements at SL : 1951 [m]
lift/drag ratio : 13.94 [ ]
climb to 5000 [m] with max payload : 5.73 [min]
climb to 10000 [m] with max payload : 17.62 [min]
descent time from 10000 [m] to 250 [m] : 24.33 [min]
ceiling limited by max. pressure differential 16225 [m]
theoretical ceiling fully loaded (mtow- 60 min.fuel: 118816 [kg] ) : 16700 [m]
calculation *10* (action radius & endurance)
range with max. payload: 6613 [km] with 19800.0 [kg] max. useful load (92.5 [%] fuel)*
range with high density pax: 7090 [km] with 179 passengers (98.4 [%] fuel)*
range with typical two-class pax: 7341 [km] with 132 passengers (100.0 [%] fuel)*
range with max.fuel : 7220 [km] with 9 crew and 170 passengers and 100.0 [%] fuel*
ferry range : 7779 [km] with 4 crew and zero payload (100.0 [%] fuel)*
max range theoretically with additional fuel tanks total 87072 [litre] fuel : 9818 [km]*
* calculated ranges without fuel reserves
Available Seat Kilometres (ASK) : 1191208 [paskm]
useful load with range 1000km : 19800 [kg]
useful load with range 1000km : 179 passengers
production (theor.max load): 17285 [tonkm/hour]
production (useful load): 17285 [tonkm/hour]
production (passengers): 141660 [paskm/hour]
oil and fuel consumption per tonkm : 0.370 [kg]
calculation *11* (operating cost)
fuel cost per hour (7970 [litre]):4782 [eur] (18 [pax-km/litre fuel])
fuel cost per seat 1000km flight (162 [pax] 2-class seating): 33.76 [eur/1000PK]
oil cost per hour: 47 [eur]
crew cost per hour : 1200 [eur]
list price 2023 : 145 [mln USD]
average flying hours in 1 year : 2800 [hours] technical life : 11 [year]
real average service life : 10 [years]
economic hours (average real flown hours): 28000 [hours] is 10 [%] less then design hours
financing interest per flying hour : 1211 [EUR]
write off per flying hour : 4472 [EUR]
time between engine failure : 14815 [hr]
can continue fly on 3 engines, low risk for emergency landing for PUF
workhours per day : 10.58 [hr]
average flight hours till crash : 0.46 [mln hr] (165 service years)
safe flight hours till fatality : 14903 [hr] (5.3 service years)
reservation pax liability/flying hour : 8.64 [SDR*] (10.80 [eur])
insurance cost per hour : 347 [eur]
engine maintenance cost per hour : 105.3 [eur]
wing maintenance cost per hour : 296.1 [eur]
fuselage maintenance cost per hour : 186.94 [eur]
maintenance cost per hour (excluding engines): 1775 [eur]
direct operating cost per hour: 13950 [eur]
DOC per seat 1000km flight (162 [pax] 2-class seating): 98.47 [eur/1000PK]
DOC per seat 1000km flight (high density seating): 89.27 [eur/1000PK]
DOC per kg cargo for a 1000km flight : 0.81 [eur/kg] (= DOC/tonkm)
passenger service charge (depart at Schiphol): 11.34 [eur]
security service charge (depart at Schiphol): 10.08 [eur]
airport take-off fee / passenger : 4.61 [eur/pax]
airport landing fee / passenger : 4.61 [eur/pax]
retour ticket price 1000km trip : 284.03 [eur/pax]
price retour ticket Schiphol-Barcelona : 338.19 [eur/pax]
accidents with fatalities > see the accident file
Literature :
Verkeersvliegtuigen (Moussault) page 15
De Nederlandse DC-8 vliegtuigen page 1 - 33
Praktisch handboek vliegtuigen deel 5 page 63 t/m 6
Jane’s all the world aircraft ’64-’65 page 211
Jane’s all the world aircraft 1970-71 page 396
https://www.boeing.com/search/results.html?q=airplane+characteristics
confidence rating regarding source data : medium - all information is only available from news, social media or unofficial sources
DISCLAIMER Above calculations are based on published data, they must be
regarded as indication not as facts.
Calculated performance and weight may not correspond with actual weights
and performances and are assumptions for which no responsibility can be taken.
Calculations are as accurate as possible, they can be fine-tuned when more data
is available, you are welcome to give suggestions and additional information
so we can improve our program. For copyright on drawings/photographs/
content please mail to below mail address
(c) B van der Zalm 16 September 2023 contact : info.aircraftinvestigation@gmail.com ac jetpax 2020.py python 3.7.4