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weight and performance calculations for the Douglas DC-8-61
Douglas DC-8-61
role : medium-range jet airliner
importance : ****
first flight : 14 March 1966 operational : February 1967 (United Airlines)
country : United States of America
design :
production : 78 -61 and 10 -61CF aircraft
general information :
The "Super DC-8" Series 61 was designed for high capacity and medium range. It had the
same wings, engines and pylons as the -55, and sacrificed range to gain capacity.
First of the extended Super Sixties, the -61 received an 11.17m longer fuselage than the
DC-8-50 series. It can accommodate 234 to 259 passengers and was the largest jet
airliner until the arrival of the Boeing 747.
*All the earlier jetliners were noisy by modern standards. Increasing traffic densities and changing public attitudes led to complaints about aircraft noise and moves to introduce restrictions. As early as 1966 the Port Authority of New York and New Jersey expressed concern about the noise to be expected from the then still-unbuilt DC-8-61, and operators had to agree to operate it from New York at lower weights to reduce noise. By the early 1970s, legislation for aircraft noise standards was being introduced in many countries, and the 60 Series DC-8s were particularly at risk of being banned from major airports* (*extraction from Wikipedia)
primary users : United Airlines, JAL, Delta Airlines, Eastern Airlines, Air Canada, Spantax
Accommodation:
flight crew : 4 cabin crew : 7
flight crew consist of pilot, co-pilot, navigator and flight engineer
passengers : seating for 215 in two class : 20 business class and 195 economy class seats ( 32 -in pitch)
high density seating for 259 passengers
engine : 4 Pratt & Whitney JT3D-3B turbofan engines of 80.17 [KN] (18022.6 [lbf])
Chord at root : 9.67 [m] at tip : 2.22 [m]
dimensions :
wingspan : 43.41 [m], length : 57.12 [m], height : 12.92 [m]
wing area : 267.9 [m^2] fuselage exterior width : 3.73 [m]
weights :
empty weight : 67536 [kg]
operating empty weight : 68993 [kg] max. structural payload : 32613 [kg]
Zero Fuel weight (ZFW) : 101606 [kg] max. landing weight (MLW) : 108864 [kg]
max.take-off weight : 147420 [kg] weight fuel : 70842 [kg] (88552 [litres])
performance :
Max. operating Mach number (Mmo) : 0.89 [Mach] (965 [km/hr]) at 9150 [m]
critical Mach speed : 0.78 [Mach]
max. cruising speed : 933 [km/hr] (Mach 0.86 ) at 9449 [m] (49 [%] power)
economic cruising speed : 845 [km/hr] (Mach 0.78 ) at 9449 [m]
service ceiling : 12000 [m]
range with max fuel and Max.TOW : 8890 [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
Delivered to Air Canada DC-8-61 CF-TJT c/n 45890 in September 1967, taken out of service in 1981 and was later converted to a freighter
with double slotted trailing edge flaps with leading edge slots ,with spoilers airfoil : NACA
sweep angle 3/4 chord: 30.0 [°]
engines attached with pylons to the wing, main landing gear attached to the wings, fuel tanks in the wings and fuselage
calculation : *1* (dimensions)
wing chord at root : 9.67 [m]
wing chord at tip : 2.22 [m]
taper ratio : 0.230 [ ]
mean wing chord : 6.17 [m]
calculated average wing chord tapered wing with rounded tips: 6.15 [m]
wing aspect ratio : 7.03 []
Oswald factor (e): 0.687 []
seize (span*length*height) : 32036 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 11.7 [kg/hr]
fuel consumption (econ. cruise speed) : 6464.5 [kg/hr] (8080.6 [litre/hr]) at 31 [%] power
distance flown for 1 kg fuel : 0.13 [km/kg] at 9449 [m] height, sfc : 65.0 [kg/KN/h]
total fuel capacity : 88552 [litre] (70842 [kg])
calculation : *3* (weight)
weight engine(s) dry : 8200.0 [kg] = 25.57 [kg/KN]
weight 178 litre oil tank : 15.11 [kg]
oil tank filled with 2.0 litre oil : 1.8 [kg]
oil in engine 3.9 litre oil : 3.5 [kg]
fuel in engine 17.5 litre fuel : 12.83 [kg]
weight fuel lines : 156.4 [kg]
weight engine cowling : 833.8 [kg]
weight double thrust reversers : 545.2 [kg]
total weight propulsion system : 9769 [kg](6.6 [%])
***************************************************************
Accommodation cabin facilities:
typical 2-class cabin layout for 215 passengers : economy : pitch : 81.3 [cm] 32.0 [-in]
( 3+3 ) seating in 36.5 rows
weight seats : 1130.0 [kg]
high density seating passengers : 259 [pax] at 6 -abreast seating in 43.2 rows, pitch
81.3 [cm] 32.0 [-in]
pax density, normal seating : 0.64 [m2/pax], high density seating : 0.53 [m2/pax]
weight 6 lavatories : 86.6 [kg]
weight 4 galleys : 270.9 [kg]
United Airlines DC-8-61 interior
weight overhead stowage for hand luggage : 75.2 [kg]
weight 4 wardrobe closets : 43.0 [kg]
weight 15 movie screens : 122.9 [kg]
weight 75 windows (47x38cm) : 67.5 [kg]
weight 2 (1.83 x 0.88 [m]) main entry doors : 108.5 [kg]
weight 2 (1.63 x 0.85 [m]) service doors : 93.7 [kg]
total belly baggage/cargo hold volume : 70.74 [m3]
cabin volume (usable), excluding flight deck : 286 [m3]
passenger compartment volume : 208 [m3]
passenger cabin max.width : 3.51 [m] cabin length : 44.30 [m] cabin height : 2.21 [m]
floor area : 137.9 [m2]
weight cabin facilities : 2118.2 [kg]
safety facilities:
weight 4 type III over wing emergency exits (51x97 cm): 66.4 [kg]
weight 4 type I emergency exits (61x142 cm): 117.4 [kg]
evacuation time with 259 passengers : 45 [sec]
weight 10 hand fire extinguisher : 31 [kg]
weight cockpit voice recorder (CVR) and flight data recorder (FDR): 20.0 [kg]
weight oxygen masks & oxygen generators : 139.8 [kg]
weight emergency flare installation : 10 [kg]
weight 4 emergency evacuation slides : 182.3 [kg]
weight safety equipment & facilities : 567 [kg]
fuselage construction:
fuselage aluminium frame : 14660 [kg]
floor loading (payload/m2): 237 [kg/m2]
weight rear pressure bulkhead : 189.6 [kg]
fuselage covering ( 498.1 [m2] duraluminium 3.29 [mm]) : 4311.9 [kg]
weight floor beams : 883.6 [kg]
weight cabin furbishing : 1214.4 [kg]
weight cabin floor : 2096.6 [kg]
weight (sound proof) isolation : 359.9 [kg]
weight 26362 [litre] main central fuel tanks empty : 1476.3 [kg]
weight empty 204 [litre] potable water tank : 18.1 [kg]
weight empty waste tank : 21.3 [kg]
weight fuselage structure : 25231.5 [kg]
Avionics:
weight VHF radio and Selcal : 9.0 [kg]
weight flight and service attendants intercom : 5.0 [kg]
weight dual cloud-collision radar : 25.0 [kg]
weight weather radar : 25.0 [kg]
weight VOR/ILS,RMI,DME,radio altimeter : 12.0 [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 : 101.0 [kg]
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 : 517 [m3]
weight air-conditioning and pressurization system : 295 [kg]
weight APU / engine starter: 40.1 [kg]
weight lighting : 71.0 [kg]
weight 210 bar hydraulic system : 106.8 [kg]
weight engine-driven 40kVA electricity generators : 53.8 [kg]
weight 22Ah battery : 12.0 [kg]
weight controls : 22.7 [kg]
weight systems : 601.0 [kg]
total weight fuselage : 28619 [kg](19.4 [%])
***************************************************************
average Take-off weight : 121646 [kg](82.5 [%])
total weight aluminium ribs (1113 ribs) : 4798 [kg]
weight engine mounts : 160 [kg]
weight 6 wing fuel tanks empty for total 62190 [litre] fuel : 3483 [kg]
weight wing covering (painted aluminium 3.13 [mm]) : 4532 [kg]
total weight aluminium spars (multi-cellular wing structure) : 4181 [kg]
weight wings : 13511 [kg]
weight wing/square meter : 50.43 [kg]
weight thermal leading-edge anti-icing : 47.8 [kg]
weight ailerons (10.98 [m2]) : 277.8 [kg]
weight fin (31.97 [m2]) : 808.5 [kg]
weight rudder (16.83 [m2]) : 408.5 [kg]
weight tailplane (stabilizer) (71.17 [m2]): 1980.0 [kg]
weight elevators (17.08 [m2]): 233.28 [kg]
weight flight control hydraulic servo actuators: 53.4 [kg]
weight trailing-edge double slotted flaps (46.54 [m2]) : 1002.6 [kg]
weight leading edge slots (1.91 [m2]) : 29.8 [kg]
weight spoilers (12.8 [m2]) : 161.8 [kg]
total weight wing construction : 22157 [kg] (32.1 [%])
*******************************************************************
tire pressure main wheels : 13.20 [Bar] (nitrogen), ply rating : 23 PR
tire speed limit : 364 [km/hr]
total tyre footprint : 0.52 [m2]
Aircraft Classification Number, MTOW on rigid runway and medium subgrade strength (B) : 45 [ ]
Can also operate from unpaved runways subgrade B
wheel pressure : 16216.2 [kg]
weight 8 Dunlop main wheels (1120 [mm] by 416 [mm]) : 1108.6 [kg]
weight 2 nose wheels : 138.6 [kg]
weight multi-disc wheel-brakes : 101.6 [kg]
weight Hydro-air flywheel detector type anti-skid units : 9.0 [kg]
weight oleo-pneumatic shock absorbers : 135.5 [kg]
weight wheel hydraulic operated retraction system : 1349.1 [kg]
weight undercarriage struts (four-wheel bogies) with axle 3835.9 [kg]
total weight landing gear : 6678.3 [kg] (4.5 [%]
*******************************************************************
********************************************************************
calculated empty weight : 67223 [kg](45.6 [%])
weight oil for 11.4 hours flying : 153.5 [kg]
weight lifejackets : 96.8 [kg]
weight 4 life rafts : 134.4 [kg]
weight catering : 225.8 [kg]
weight water : 180.6 [kg]
weight crew : 891 [kg]
weight crew lugage,nav.chards,flight doc.,miscell.items : 88 [kg]
operational weight empty : 68993 [kg] (46.8 [%])
********************************************************************
weight 215 passengers : 16555 [kg]
weight luggage : 3440 [kg]
weight cargo : 12618 [kg] (cargo+luggage/m3 belly : 215 [kg/m3])
zero fuel weight (ZFW): 101606 [kg](68.9 [%])
weight fuel for landing (1.1 hours flying) : 7258 [kg]
max. landing weight (MLW): 108864 [kg](73.8 [%])
max. fuel weight : 139835 [kg] (94.9 [%])
payload with max fuel : 82 passengers+luggage 7585 [kg]
published maximum take-off weight : 147420 [kg] (100.0 [%])
Delta Airlines DC-8-61 N1303L taking off at Miami, March 1978
calculation : * 4 * (engine power)
power loading (Take-off) : 460 [kg/KN]
power loading (Take-off) 1 PUF: 613 [kg/KN]
max. total take-off power : 320.7 [KN]
calculation : *5* (loads)
manoeuvre load : 7.6 [g] at 1000 [m]
limit load : 2.5 [g] ultimate load : 3.8 [g] load factor : 1.1 [g]
design flight time : 2.10 [hours]
design cycles : 14750 sorties, design hours : 30975 [hours]
max. wing loading (MTOW & flaps retracted) : 550 [kg/m2]
wing stress (2 g) during operation : 186 [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) : 13.47 ["]
max. angle of attack (full flaps) : 12.93 ["]
angle of attack at max. speed : 1.63 ["]
calculation : *7* (lift & drag ratios
lift coefficient at angle of attack 0° : 0.15 [ ]
lift coefficient at max. speed : 0.29 [ ]
lift coefficient at max. angle of attack : 1.27 [ ]
max. lift coefficient full flaps : 1.73 [ ]
drag coefficient at max. speed : 0.0366 [ ]
drag coefficient at econ. cruise speed : 0.0305 [ ]
induced drag coefficient at econ. cruise speed : 0.0075 [ ]
drag coefficient (zero lift) : 0.0230 [ ]
lift/drag ratio at econ. speed : 7.80 [ ]
calculation : *8* (speeds
take-off decision speed (V1) : 242 [km/u] (131 [kt])
lift-off speed (VLOF) : 268 [km/u] (145 [kt])
take-off safety speed (V2) : 284 [km/u] (153 [kt])
steady initial climb speed (V4) : 310 [km/u] (167 [kt])
flap retraction speed (V3) at 500m (OW loaded : 140956 [kg]): 312 [km/u] (168 [kt])
climb speed (to FL150 with 65 [%] power) : 523 [km/hr] (283 [kt])
max. endurance speed (Vbe): 534 [km/u] min. fuel/hr : 5562 [kg/hr] at height : 6401 [m]
max. range speed (Vbr): 831 [km/u] (0.78 [mach]) min. fuel consumption : 7.17 [kg/km] at cruise height : 10668 [m]
max. cruising speed : 933 [km/hr] (504 [kt]) at 9449 [m] (power:42 [%])
max. operational speed (Mmo) : 965 [km/hr] (Mach 0.89 ) at 9150 [m] (power:48 [%])
airflow at cruise speed per engine : 163.8 [kg/s]
speed of thrust jet : 1677 [km/hr]
initial descent speed 10000 - 7315 [m]: Mach 0.82
descent speed 7315 - 3048 [m]: 537 [km/u] (290 [kt])
approach speed 3048 - 500 [m] (clean): 463 [km/u] (250 [kt])
stalling speed clean at 500 [m] height at Max.Landing Weight : 108864 [kg]): 264 [km/u] (143 [kt])
Approach speed DC-8-61 at MLW 108864 [kg] (240000 LB) : 143 kts = 264 km/h
final approach speed (landing speed) at sea-level with full flaps VREF (max. landing weight):
264 [km/u] (142 [kt])
ICAO Aircraft Approach Category (APC) : D
stalling speed at sea-level with full flaps VSO (max. landing weight): 203 [km/u]
rate of climb at sea-level ROC (loaded, 65 % power) : 693 [m/min]
rate of climb at sea-level ROC (loaded, 75% power) : 913 [m/min]
rate of climb at 1000 [m] with 1 engine out (PUF/MTOW, 100 % power on remaining engines) : 1645 [m/min]
rate of climb at 1000 [m] with 2 engines out (2xPUF / MTOW) : 834 [m/min]
max.rate of descent with landing gear extended, with use of spoilers: 457 [m/min]
calculation : *9* (regarding various performances)
high wheel pressure, can only take off from paved runways
take-off distance at sea-level concrete runway : 2862 [m]
ICAO Aerodrome Reference Code : 4D
take-off distance at sea-level over 15 [m] height : 3051 [m]
FAR TO runway length requirement at MTOW, standard day at SL (ASDA): 3017 [m]
landing distance (MLW) : 813 [m]
Landing run over 15m, sea level, dry runway, MLW 108864 kg (240000 lb) : 6135 ft > 1870 [m]
landing distance (C.A.R.) from 15 [m] at SL, dry runway : 1870 [m]
landing distance (C.A.R.) from 15 [m] at SL, wet runway : 2170 [m]
FAR landing runway length requirements at SL : 1883 [m]
lift/drag ratio : 12.84 [ ]
climb to 5000 [m] with max payload : 6.68 [min]
climb to 10000 [m] with max payload : 20.54 [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: 140956 [kg] ) : 16400 [m]
calculation *10* (action radius & endurance)
range with max. payload: 5661 [km] with 32613.0 [kg] max. useful load (64.7 [%] fuel)*
range with high density pax: 6847 [km] with 259 passengers (76.7 [%] fuel)*
range with typical two-class pax: 7430 [km] with 215 passengers (82.5 [%] fuel)*
MTOW 325000 lb = 147420 kg max fuel = 23393 US gallon = 88425 litre, range with max fuel : 4800 nm = 8890 km with 17500 lb payload = 7938 kg. Range with 259 pax & luggage (= 53095 lb = 24084 kg > 93 kg/pax)= 3200 nm = 5926 km
range with max.fuel : 9260 [km] with 11 crew and 82 passengers and 100.0 [%] fuel*
ferry range : 9606 [km] with 4 crew and zero payload (100.0 [%] fuel)*
max range theoretically with additional fuel tanks total 99250 [litre] fuel : 10573 [km]*
* calculated ranges without fuel reserves
Available Seat Kilometres (ASK) : 1684918 [paskm]
useful load with range 1000km : 32613 [kg]
useful load with range 1000km : 259 passengers
production (theor.max load): 30428 [tonkm/hour]
production (useful load): 30428 [tonkm/hour]
production (passengers): 218062 [paskm/hour]
oil and fuel consumption per tonkm : 0.213 [kg]
calculation *11* (operating cost)
fuel cost per hour (8081 [litre]):4848 [eur] (27 [pax-km/litre fuel])
fuel cost per seat 1000km flight (234 [pax] 2-class seating): 22.23 [eur/1000PK]
oil cost per hour: 48 [eur]
crew cost per hour : 1500 [eur]
list price 2023 : 178 [mln USD]
average flying hours in 1 year : 2550 [hours] technical life : 12 [year]
real average service life : 13 [years]
economic hours (average real flown hours) : 33150 [hours]
financing interest per flying hour : 1630 [EUR]
write off per flying hour : 4629 [EUR]
time between engine failure : 10307 [hr]
can continue fly on 3 engines, low risk for emergency landing for PUF
workhours per day : 9.48 [hr]
average flight hours till crash : 0.86 [mln hr] (338 service years)
Nationair C-GMXQ which crashed 11 July 1991 near Jeddah
safe flight hours till fatality : 8765 [hr] (3.4 service years)
reservation pax liability/flying hour : 14.70 [SDR*] (18.37 [eur])
insurance cost per hour : 229 [eur]
engine maintenance cost per hour : 225.0 [eur]
wing maintenance cost per hour : 280.7 [eur]
fuselage maintenance cost per hour : 225.91 [eur]
tire life (time till worn out) : 103 [cycles]
maintenance cost per hour (excluding engines): 2265 [eur]
direct operating cost per hour: 15393 [eur]
DOC per seat 1000km flight (234 [pax] 2-class seating): 70.59 [eur/1000PK]
DOC per seat 1000km flight (high density seating): 63.70 [eur/1000PK]
DOC per kg cargo for a 1000km flight : 0.51 [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 : 3.77 [eur/pax]
airport landing fee / passenger : 3.77 [eur/pax]
retour ticket price 1000km trip : 218.99 [eur/pax]
price retour ticket Schiphol-Barcelona : 257.82 [eur/pax]
accidents with fatalities > see the accident file
Literature :
https://www.boeing.com/search/results.html?q=airplane+characteristics
Verkehrsflugzeuge page 58
Jane’s commercial transport aircraft page185
De Nederlandse DC-8 vliegtuigen page 1 – 33
Jane’s all the world aircraft 1970-71 page
Verkeersvliegtuigen (Moussault) page 157
Verkeersvliegtuigen B.van der Klaauw page 64
Douglas DC-8-61 - Price, Specs, Photo Gallery, History - Aero Corner
https://contentzone.eurocontrol.int/aircraftperformance/default.aspx?
https://www.boeing.com/search/results.html?q=airplane+characteristics
Spantax DC-8-61 EC-DVC
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 08 October 2023 contact : info.aircraftinvestigation@gmail.com ac jetpax 2020.py python 3.7.4