Aircraft investigation >>>>>>> HOME PAGE
weight and performance calculations for the Douglas DC-7B
Douglas DC-7B
role : heavy prop 80
importance : ****
first flight : 25 April 1955 operational : June 1955
country : United States of America
design :
production : 96 aircraft at Santa Monica
general information :
Long-range version designed for trans-Atlantic use with higher TOW and more fuel.
Additional fuel capacity was created by extending the engine nacelles.
Total fuel capacity : 24400 litre. Basic price : 982000 USD in 1955
Pan American took the DC-7B into service on June 13, 1955 on the New York –
London route.
Primary users : Pan American, Delta, Internord, Panagra, SAA, Transair, Eastern
Airlines
flight crew : 4 cabin crew : 3 passengers : 74
flight crew consist of pilot, co-pilot, radio operator and engineer
powerplant : 4 Wright R-3350-18DA4 Turbo Compound air-cooled 18 -cylinder radial engine 1700 [hp](1267.7 KW)
normal rating, supercharged engine, high blower, constant power to height : 7400 [m]
and with 3250 [hp](2423.5 KW) available for take-off
dimensions :
wingspan : 35.81 [m], length : 33.52 [m], height : 9.37 [m]
wing area : 135.9 [m^2]
weights :
max.take-off weight : 57152 [kg]
empty weight operational : 31000 [kg] useful load : 9759 [kg]
performance :
maximum continuous speed : 653 [km/u] op 7400 [m]
normal cruise speed : 578 [km/u] op 7165 [m] (78 [%] power)
service ceiling : 7620 [m]
range with max fuel : 9171 [km] and allowance for 949.1 [km] diversion and 30 [min]
hold
DC-7B N836D at San Juan Int’l apt. on 16 May 2011
description :
low-winged monoplane with retractable landing gear with nose wheel
tapered multi-cellular wing with flush-riveted stressed skin
with Fowler flaps airfoil : NACA
engines and landing gear attached to the wings, fuel tanks in the wings
construction : all-metal aluminium-alloy stressed-skin construction with pressurized fuselage
fuselage shape : O
airscrew :
four Hamilton-Standard constant speed, reversible pitch 4 -bladed tractor airscrews with max. efficiency :0.76 [ ]
diameter airscrew 4.10 [m]
relative pitch (J) : 2.53 [ ]
power loading prop : 154.60 [KW/m]
theoretical pitch without slip : 11.52 [m]
blade angle prop at max.speed : 51.02 [ ]
tip-speed close to speed of sound (above Mach 0.85) > loose of efficiency
reduction : 0.44 [ ]
airscrew revs : 1050 [r.p.m.]
aerodynamic pitch at max. continuous speed 10.37 [m]
blade-tip speed at max.continuous speed : 289 [m/s]
propellor noise in flight : 100 [Db]
calculation : *1* (dimensions)
measured wing chord : 3.77 [m] at 50% wingspan
mean wing chord : 3.80 [m]
calculated average wing chord tapered wing with rounded tips: 3.68 [m]
wing aspect ratio : 9.4 []
seize (span*length*height) : 11247 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 40.6 [kg/hr]
fuel consumption (econ. cruise speed) : 993.2 [kg/hr] (1355.0 [litre/hr]) at 78 [%] power
distance flown for 1 kg fuel : 0.58 [km/kg] at 7165 [m] height, sfc : 250.0 [kg/kwh]
estimated total fuel capacity : 24402 [litre] (17887 [kg])
calculation : *3* (weight)
weight engine(s) dry with reduction gear : 6000.0 [kg] = 1.18 [kg/KW]
weight 987.1 litre oil tank : 83.91 [kg]
oil tank filled with 38.0 litre oil : 34.1 [kg]
oil in engine 28.2 litre oil : 25.4 [kg]
fuel in engine 34.6 litre fuel : 25.35 [kg]
weight 576.1 litre gravity patrol tank(s) : 86.4 [kg]
weight jet stacks : 126.8 [kg]
weight NACA cowling 56.8 [kg]
weight variable pitch control : 33.5 [kg]
weight airscrew(s) incl. boss & bolts : 945.3 [kg]
total weight propulsion system : 7384 [kg](12.9 [%])
***************************************************************
fuselage aluminium frame : 6379 [kg]
typical cabin layout for 74 passengers : pitch : 81 [cm] ( 2+2 ) seating in 18.5 rows
pax density (normal seating) : 0.87 [m2/pax]
high density seating passengers : 109 at 5 -abreast seating in 21.8 rows
weight 5 toilets : 40.7 [kg]
weight 6 hand fire extinguisher : 17 [kg]
weight pantry : 164.4 [kg]
weight 39 windows : 35.1 [kg]
weight 4 emergency exits : 12.0 [kg]
weight 4 life rafts : 92.5 [kg]
weight oxygen masks & oxygen generators : 48.1 [kg]
weight emergency flare installation : 10 [kg]
weight emergency evacuation slide : 15 [kg]
weight 2 entrance/exit doors : 24.0 [kg]
weight 2 freight doors (belly) : 8.0 [kg]
extra main deck space for freight/mail/luggage etc. : 3.79 [m3]
cabin volume (usable), excluding flight deck : 134.49 [m3]
passenger cabin max.width : 2.99 [m] cabin length : 21.49 [m] cabin height : 2.36 [m]
pressure at cruise height 6100.00 [m] : 0.47 [kg/cm2] cabin pressure : 0.77 [kg/cm2]
weight rear pressure bulkhead : 158.1 [kg]
weight air pressurization system : 37.8 [kg]
fuselage covering ( 223.8 [m2] duraluminium 3.80 [mm]) : 2227.5 [kg]
weight floor beams : 119.2 [kg]
weight cabin furbishing : 448.8 [kg]
weight cabin floor : 391.7 [kg]
fuselage (sound proof) isolation : 91.6 [kg]
weight radio transceiver equipment : 7.0 [kg]
weight radio direction finding (RDF) equipment : 5.0 [kg]
weight artificial horizon : 1.1 [kg]
weight instruments. : 13.0 [kg]
weight APU / engine starter: 63.4 [kg]
weight lighting : 18.5 [kg]
weight electricity generator : 18.5 [kg]
weight controls : 14.5 [kg]
weight seats : 405.0 [kg]
weight air conditioning : 111 [kg]
total weight fuselage : 10862 [kg](19.0 [%])
***************************************************************
total weight aluminium ribs (769 ribs) : 2038 [kg]
weight titanium firewalls and engine mounts : 180 [kg]
weight fuel tanks empty for total 23826 [litre] fuel : 1906 [kg]
weight wing covering (painted aluminium 2.76 [mm]) : 2022 [kg]
total weight aluminium spars (multi-cellular wing structure) : 2231 [kg]
weight wings : 6291 [kg]
weight wing/square meter : 46.29 [kg]
cantilever wing without bracing cables
weight rubber de-icing boots : 39.4 [kg]
weight fin & rudder (14.9 [m2]) : 691.3 [kg]
weight stabilizer & elevator (15.3 [m2]): 708.8 [kg]
weight flight control hydraulic servo actuators: 46.1 [kg]
weight fowler flaps (11.3 [m2]) : 268.1 [kg]
total weight wing surfaces & bracing : 10131 [kg] (17.7 [%])
*******************************************************************
wheel pressure : 14288.0 [kg]
weight 4 Dunlop main wheels (1330 [mm] by 266 [mm]) : 708.3 [kg]
weight nose wheel : 88.5 [kg]
weight hydraulic wheel-brakes : 40.8 [kg]
weight pneumatic-hydraulic shock absorbers : 54.3 [kg]
weight wheel hydraulic operated retraction system : 155.7 [kg]
weight undercarriage struts with axle 1297.8 [kg]
total weight landing gear : 2335.5 [kg] (4.1 [%]
*******************************************************************
********************************************************************
calculated empty weight : 30713 [kg](53.7 [%])
weight oil for 19.0 hours flying : 772.4 [kg]
calculated operational weight empty : 31485 [kg] (55.1 [%])
published operational weight empty : 31000 [kg] (54.2 [%])
weight crew : 567 [kg]
weight fuel for 2.0 hours flying : 1986 [kg]
weight catering : 410.9 [kg]
weight water : 328.8 [kg]
********************************************************************
operational weight empty: 34778 [kg](60.9 [%])
weight 74 passengers : 5698 [kg]
weight luggage : 903 [kg]
weight cargo : 3158 [kg]
operational weight loaded: 44537 [kg](77.9 [%])
fuel reserve : 12614.6 [kg] enough for 12.70 [hours] flying
operational weight fully loaded : 57152 [kg] with fuel tank filled for 82 [%]
published maximum take-off weight : 57152 [kg] (100.0 [%])
calculation : * 4 * (engine power)
power loading (Take-off) : 5.90 [kg/kW]
power loading (operational without useful load) : 6.86 [kg/kW]
power loading (Take-off) 1 PUF: 7.86 [kg/kW]
max.total take-off power : 9694.1 [kW]
calculation : *5* (loads)
manoeuvre load : 4.8 [g] at 1000 [m]
limit load : 2.5 [g] ultimate load : 3.8 [g] load factor : 1.2 [g]
design flight time : 11.11 [hours]
design cycles : 3115 sorties, design hours : 34598 [hours]
operational wing loading : 3618 [N/m^2]
wing stress (3 g) during operation : 234 [N/kg] at 3g emergency manoeuvre
calculation : *6* (angles of attack)
angle of attack zero lift : -1.79 ["]
max. angle of attack (stalling angle, clean) : 12.84 ["]
max. angle of attack (full flaps) : 11.95 ["]
angle of attack at max. speed : 1.24 ["]
calculation : *7* (lift & drag ratios
lift coefficient at angle of attack 0° : 0.16 [ ]
lift coefficient at max. speed : 0.27 [ ]
lift coefficient at max. angle of attack : 1.31 [ ]
max.lift coefficient full flaps : 1.74 [ ]
induced drag coefficient at max.speed : 0.0032 [ ]
drag coefficient at max. speed : 0.0155 [ ]
drag coefficient (zero lift) : 0.0122 [ ]
calculation : *8* (speeds
stalling speed at sea-level (OW loaded : 56159 [kg]): 256 [km/u]
stalling speed at sea-level with full flaps (normal landing weight): 163 [km/u]
landing speed at sea-level (normal landing weight : 43133 [kg]): 187 [km/hr]
max. rate of climb speed : 272 [km/hr] at sea-level
max. endurance speed : 292 [km/u] min.fuel/hr : 677 [kg/hr] at height : 610 [m]
max. range speed : 520 [km/u] min. fuel consumption : 2.009 [kg/km] at cruise height : 6401 [m]
cruising speed : 578 [km/hr] at 7165 [m] (power:82 [%])
max. continuous speed* : 653.00 [km/hr] at 7400 [m] (power:100 [%])
climbing speed at sea-level (loaded) : 284 [m/min]
climbing speed at 1000 [m] with 1 engine out (PUF / MTOW) : 286 [m/min]
climbing speed at 1000 [m] with 2 engines out (2xPUF / MTOW) : 75 [m/min]
calculation : *9* (regarding various performances)
take-off speed : 310.0 [km/u]
emergency/TO power : 3250 [hp] at 2800 [rpm]
static prop wash : 177 [km/u]
high wheel pressure, can only take off from paved runways
take-off distance at sea-level concrete runway : 1863 [m]
take-off distance at sea-level over 15 [m] height : 2102 [m]
landing run : 755 [m]
landing run from 15 [m] : 1498 [m]
lift/drag ratio : 21.62 [ ]
climb to 1000m with max payload : 8.19 [min]
climb to 2000m with max payload : 17.38 [min]
climb to 3000m with max payload : 27.95 [min]
climb to 5000 [m] with max payload : 60.75 [min]
practical ceiling (operational weight empty 34778 [kg] ) : 10400 [m]
practical ceiling fully loaded (mtow- 30 min.fuel:56655 [kg] ) : 6600 [m]
calculation *10* (action radius & endurance)
published range : 9171 [km] with 7 crew and 9340.6 [kg] useful load and 88.1 [%] fuel (no reserves)
range : 8928 [km] with 7 crew and 9759.0 [kg] useful load and 85.8 [%] fuel
range : 10765 [km] with 74.0 passengers with each 12.2 [kg] luggage and 103.4 [%] fuel
Available Seat Kilometres (ASK) : 796643 [paskm]
max range theoretically with additional fuel tanks total 34905.5 [litre] fuel : 12737 [km]
useful load with range 500km : 24727 [kg]
useful load with range 500km : 74 passengers
production (theor.max load): 14292 [tonkm/hour]
production (useful load): 5641 [tonkm/hour]
production (passengers): 42772 [paskm/hour]
combi aircraft mail/freight/passengers
oil and fuel consumption per tonkm : 0.072 [kg]
fuel cost per paskm : 0.024 [eur]
crew cost per paskm : 0.021 [eur]
economic hours : 18250 [hours] is less then design hours
time between engine failure : 2111 [hr]
can continue fly on 3 engines, low risk for emergency landing for PUF
writing off per paskm : 0.033 [eur]
insurance per paskm : 0.0001 [eur]
maintenance cost per paskm : 0.158 [eur]
direct operating cost per paskm : 0.236 [eur]
direct operating cost per tonkm (max. load): 0.705 [eur]
direct operating cost per tonkm (normal useful load): 1.787 [eur]
Literature :
Praktisch handboek vliegtuigen deel 5 page 55
Verkeersvliegtuigen Moussault page 117
Piston-engined airliners page 59,60
Amerikaanse viegtuigbouwers page 64
* max. continuous speed : max.level speed maintainable for minimal 30 min.
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 22 January 2022 contact : info.aircraftinvestigation@gmail.com python 3.7.4