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weight and performance calculations for the Short S.8 Calcutta
Short S.8 Calcutta
importance : ***
first flight : 21 February 1928 operational : August 1928
country : United-Kingdom
design :
production : 7 aircraft at Rochester
general information :
Successful flying boat. Fuel capacity : 2200 litre. The S.8 flew over the Mediterranean sea for Imperial Airways, between Genua and Alexandria (stops en-route : Rome, Naples, Corfu, Athens, Suda Bay, Tobruk) as part of the long distance route between London and Karachi. Besides 15 passengers it could carry freight and mail. During the flight meals were served.
users : Imperial Airways
crew : 3 passengers : 15
engine : 3 Bristol Jupiter XIF air-cooled 9 -cylinder radial engine 500 [hp](372.9 KW)
without supercharger
dimensions :
wingspan : 28.35 [m], length : 20.35 [m], height : 7.24[m]
wing area : 169.5 [m^2]
weights :
max.take-off weight : 10206 [kg]
empty weight operational : 6280 [kg] useful load : 1750 [kg]
performance :
maximum speed :190 [km/hr] at sea-level
cruise speed :171 [km/u] op 100 [m]
service ceiling : 4100 [m]
range : 991 [km]
description :
2-bay biplane flying boat
2 (aid) tip floats
two spar upper and lower wing
all-metal (duraluminium) airplane
engines, landing gear and fuel attached to the wings, useful load in the fuselage
airscrew :
three fixed pitch 4 -bladed tractor airscrews with max. efficiency :0.61 [ ]
estimated diameter airscrew 3.07 [m]
power loading prop : 60.72 [KW/m]
prop efficiency ratio: 7.24 [1/s]
angle of attack prop : 23.64 [ ]
reduction : 0.50 [ ]
airscrew revs : 1000 [r.p.m.]
pitch at Max speed 3.17 [m]
blade-tip speed at Vmax and max revs. : 169 [m/s]
calculation : *1* (dimensions)
wing chord : 3.50 [m]
mean wing chord : 2.99 [m]
calculated wing chord (rounded tips): 3.26 [m]
wing aspect ratio : 9.48 []
estimated gap : 3.10 [m]
gap/chord : 1.04 [ ]
seize (span*length*height) : 4177 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 28.0 [kg/hr]
fuel consumption(cruise speed) : 245.3 [kg/hr] (334.7 [litre/hr]) at 68 [%] power
distance flown for 1 kg fuel : 0.70 [km/kg] at 2050 [m] height, sfc : 320.2 [kg/kwh]
estimated total fuel capacity : 2201 [litre] (1614 [kg])
calculation : *3* (weight)
weight engine(s) dry : 1389.0 [kg] = 1.24 [kg/KW]
weight 244.6 litre oil tank : 20.79 [kg]
oil tank filled with 8.4 litre oil : 7.5 [kg]
oil in engine 6.2 litre oil : 5.6 [kg]
fuel in engine 7.6 litre fuel : 5.59 [kg]
weight 142.3 litre gravity patrol tank(s) : 21.3 [kg]
weight inertia starter : 9.1 [kg]
weight airscrew(s) (wood) incl. boss & bolts : 152.0 [kg]
total weight propulsion system : 1590 [kg](15.6 [%])
***************************************************************
fuselage aluminium frame : 780 [kg]
cabin layout : pitch : 87 [cm] (2+1) seating in 5.0 rows
weight toilet : 8 [kg]
weight pantry : 12.2 [kg]
weight 2 fire extinguisher : 6 [kg]
weight 10.0 windows : 9.00 [kg]
passenger cabin width : 2.07 [m] cabin length : 4.95 [m] cabin height : 1.90 [m]
weight cabin furbishing : 50.80 [kg]
weight cabin floor : 65.50 [kg]
fuselage covering ( 78.2 [m2] duraluminium 1.0 [mm]) : 206.7 [kg]
duraluminium hull (gauche : 0.96 [cm]): 579.3 [kg]
weight radio navigation equipment : 7.0 [kg]
weight instruments. : 4.0 [kg]
weight lighting : 3.8 [kg]
weight controls : 10.1 [kg]
weight seats : 90.0 [kg]
weight air conditioning : 22 [kg]
total weight fuselage : 1842 [kg](18.1 [%])
***************************************************************
weight wing covering (painted aluminium 0.75 mm) : 686 [kg]
total weight ribs (174 ribs) : 364 [kg]
weight engine mounts : 56 [kg]
weight fuel tanks empty for total 2059 [litre] fuel : 165 [kg]
load on front upper spar (clmax) per running metre : 2689.3 [N]
load on rear upper spar (vmax) per running metre : 1015.4 [N]
total weight 8 spars : 501 [kg]
weight wings : 1552 [kg]
weight wing/square meter : 9.16 [kg]
weight 8 interplane struts & cabane : 408.2 [kg]
weight cables (154 [m]) : 203.3 [kg] (= 1317 [gram] per metre)
diameter cable : 14.7 [mm]
weight fin & rudder (9.3 [m2]) : 86.8 [kg]
weight stabilizer & elevator (19.1 [m2]): 175.9 [kg]
total weight wing surfaces & bracing : 2647 [kg] (25.9 [%])
*******************************************************************
weight 2 tip floats : 103 [kg] (1.0 [%])
*******************************************************************
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calculated empty weight : 6183 [kg](60.6 [%])
weight oil for 7.0 hours flying : 194.5 [kg]
calculated operational weight empty : 6377 [kg] (62.5 [%])
published operational weight empty : 6280 [kg] (61.5 [%])
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| | o | |
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~U~
weight crew : 243 [kg]
weight fuel for 2.0 hours flying : 491 [kg]
********************************************************************
operational weight empty: 7111 [kg](69.7 [%])
weight 15 passengers : 1155 [kg]
weight luggage & freight : 345 [kg]
operational weight loaded: 8611 [kg](84.4 [%])
fuel reserve : 1123.0 [kg] enough for 4.58 [hours] flying
possible additional useful load : 472 [kg]
operational weight fully loaded : 10206 [kg] with fuel tank filled for 100 [%]
published maximum take-off weight : 10206 [kg] (100.0 [%])
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calculation : * 4 * (engine power)
power loading (Take-off) : 9.12 [kg/kW]
power loading (operational without useful load) : 6.36 [kg/kW]
power loading (Take-off) 1 PUF: 13.69 [kg/kW]
total power : 1118.6 [kW] at 2000 [r.p.m]
calculation : *5* (loads)
manoeuvre load : 2.7 [g] at 1000 [m]
limit load : 3.0 [g] ultimate load : 4.5 [g] load factor : 2.0 [g]
design flight time : 4.06 [hours]
design cycles : 3584 sorties, design hours : 14538 [hours]
operational wing loading : 411 [N/m^2]
wing stress (3 g) during operation : 135 [N/kg] at 3g emergency manoeuvre
calculation : *6* (angles of attack)
angle of attack zero lift : -1.35 ["]
max. angle of attack (stalling angle) : 11.38 ["]
angle of attack at max. speed : 1.39 ["]
calculation : *7* (lift & drag ratios
lift coefficient at angle of attack 0° :0.12 [ ]
lift coefficient at max. angle of attack : 1.13 [ ]
lift coefficient at max. speed : 0.24 [ ]
induced drag coefficient at max. speed : 0.0035 [ ]
drag coefficient at max. speed : 0.0442 [ ]
drag coefficient (zero lift) : 0.0407 [ ]
calculation : *8* (speeds
stalling speed at sea-level (OW loaded : 9961 [kg]): 104 [km/u]
landing speed at sea-level: 122 [km/hr]
min. drag speed (max endurance) : 134 [km/hr] at 2050 [m](power :53 [%])
min. power speed (max range) : 134 [km/hr] at 2050 [m] (power:53 [%])
max. rate of climb speed : 114.1 [km/hr] at sea-level
cruising speed : 171 [km/hr] op 2050 [m] (power:75 [%])
design speed prop : 180 [km/hr]
maximum speed : 190 [km/hr] op 100 [m] (power:106 [%])
climbing speed at sea-level : 313 [m/min]
calculation : *9* (regarding various performances)
take-off speed : 126.0 [km/u]
emergency/TO power : 525 [hp] at 2200 [rpm]
propellor partly stalled > high angle of attack propellor
static prop wash : 71 [km/u]
take-off distance at sea-level : 800 [m]
lift/drag ratio : 10.15 [ ]
climb to 1000m with max payload : 7.56 [min]
climb to 2000m with max payload : 19.29 [min]
climb to 3000m with max payload : 37.43 [min]
practical ceiling (operational weight 7111 [kg] ) : 5888 [m]
practical ceiling fully loaded (mtow- 30 min.fuel:10083 [kg] ) : 3733 [m]
max. dive speed : 488.9 [km/hr] at 2733 [m] height
turning speed at CLmax : 134.5 [km/u] at 50 [m] height
turn radius at 50m: 67 [m]
time needed for 360* turn 11.3 [seconds] at 50m
load factor at max. angle turn 2.34 ["g"]
calculation *10* (action radius & endurance)
published range : 991 [km] with 3 crew and 2164.1 [kg] useful load and 88.1 [%] fuel
range : 1454 [km] with 3 crew and 1500.0 [kg] useful load and 129.3 [%] fuel
range : 1590 [km] with 15.0 passengers with each 10 [kg] luggage and 141.3 [%] fuel
Available Seat Kilometers (ASK) : 23848 [paskm]
max range theoretically with additional fuel tanks total 5113.1 [litre] fuel : 2612 [km]
useful load with range 500km : 3031 [kg]
useful load with range 500km : 15 passengers
production (useful load): 518.22 [tonkm/hour]
production (passengers): 2565.00 [paskm/hour]
combi aircraft mail/freight/passengers
oil and fuel consumption per tonkm : 0.53 [kg]
oil and fuel consumption per paskm : 0.05 [kg]
fuel cost per paskm : 0.05 [eur]
crew cost per paskm : 0.06 [eur]
economic hours : 12775 [hours] is less then design hours
time between engine failure : 55 [hr]
writing off per paskm : 0.08 [eur]
insurance per paskm : 0.03 [eur]
rigging cost per paskm : 0.02 [eur]
maintenance cost per paskm : 0.50 [eur]
direct operating cost per paskm : 0.70 [eur]
direct operating cost per tonkm : 7.05 [eur]
Literature :
Piston-engined airliners page 23
Praktisch handboek vliegtuigen deel 2 page 86,87
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/
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(c) B van der Zalm 10 May 2021 contact : info.aircraftinvestigation@gmail.com python 3.7.4