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weight and performance calculations for the Albatros W.4
Early W.4 with Windhoff radiators to the side of the fuselage
Albatros W.4
role : light maritime single-seat scout (ship based)
importance : ***
first flight : operational : September 1916
country : Germany
design :
production : 118 aircraft
general information :
Floatplane derived of the Albatros D.I fighter biplane. It had a new wing with greater span and a modified tail section. It had to protect the German naval bases, like Zeebrugge and Borkum, from the harassing British flying boats and seaplanes. The seaplanes it could easily master, but the British RNAS flying boats operating from Yarmouth and Felixtowe were well armed and were not easily deterred by the Albatros W.4. Fuel capacity : two separate 73 litre petrol tanks, oil capacity : 13 litre
users : Germany
crew : 1
armament : 2 synchronized 7.92 [mm] (0.312 in) Spandau LMG 08/15 machine-guns
engine : 1 Mercedes D.III liquid-cooled 6 -cylinder inline engine 163 [hp](121.5 KW)
dimensions :
wingspan : 9.5 [m], length : 8.5 [m], height : 3.7[m]
wing area : 31.6 [m^2]
weights :
max.take-off weight : 1070 [kg]
empty weight operational : 790 [kg] bombload : 0 [kg]
performance :
maximum speed : 160 [km/hr] at sea-level
climbing speed : 198 [m/min]
service ceiling : 3000 [m]
endurance : 2.9 [hours]
estimated action radius : 211 [km]
description :
1-bay two float biplane no tip floats
two spar upper and lower wing
engines, landing gear, fuel and bombs in or attached to the fuselage
airscrew :
fixed pitch 2 -bladed tractor airscrew with max. efficiency :0.63 [ ]
estimated diameter airscrew 2.80 [m]
angle of attack prop : 16.11 [ ]
reduction : 1.00 [ ]
airscrew revs : 1400 [r.p.m.]
pitch at Max speed 1.90 [m]
blade-tip speed at Vmax and max revs. : 210 [m/s]
calculation : *1* (dimensions)
mean wing chord : 1.66 [m]
calculated wing chord (rounded tips): 1.90 [m]
wing aspect ratio : 5.71 []
estimated gap : 1.53 [m]
gap/chord : 0.92 [ ]
seize (span*length*height) : 299 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 2.6 [kg/hr]
fuel consumption(cruise speed) : 32.3 [kg/hr] (44.0 [litre/hr]) at 75 [%] power
distance flown for 1 kg fuel : 4.46 [km/kg]
estimated total fuel capacity : 146 [litre] (107 [kg])
calculation : *3* (weight)
weight engine(s) dry : 299.0 [kg] = 2.46 [kg/KW]
weight 13 litre oil tank : 1.6 [kg]
oil tank filled with 0.9 litre oil : 0.8 [kg]
oil in engine 7 litre oil : 6.1 [kg]
fuel in engine 1 litre fuel : 0.6 [kg]
weight 19 litre gravity patrol tank(s) : 1.8 [kg]
weight radiator : 17.4 [kg]
weight exhaust pipes & fuel lines 11.6 [kg]
weight cowling 4.9 [kg]
weight airscrew(s) (wood) incl. boss & bolts : 19.0 [kg]
total weight propulsion system : 361 [kg](33.8 [%])
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fuselage skeleton (wood gauge : 6.38 [cm]): 78 [kg]
bracing : 4.1 [kg]
fuselage covering ( 10.6 [m2] doped linen fabric) : 3.4 [kg]
weight controls + indicators: 5.8 [kg]
weight seats : 3.0 [kg]
weight other details, lighting set, etc. : 5.1 [kg]
weight 128 [litre] main fuel tank empty : 12.3 [kg]
weight engine mounts & firewalls : 6 [kg]
total weight fuselage : 118 [kg](11.0 [%])
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weight wing covering (doped linen fabric) : 20 [kg]
total weight ribs (53 ribs) : 64 [kg]
load on front upper spar (clmax) per running metre : 900.8 [N]
load on rear upper spar (vmax) per running metre : 311.3 [N]
total weight 8 spars : 47 [kg]
weight wings : 130 [kg]
weight wing/square meter : 4.13 [kg]
weight 4 interplane struts & cabane : 12.9 [kg]
weight cables (48 [m]) : 3.5 [kg] (= 73 [gram] per metre)
diameter cable : 3.5 [mm]
weight fin & rudder (1.3 [m2]) : 5.6 [kg]
weight stabilizer & elevator (3.6 [m2]): 14.9 [kg]
total weight wing surfaces & bracing : 167 [kg] (15.6 [%])
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weight machine-gun(s) : 34.0 [kg]
weight ammunition magazine(s) :3.5 [kg]
weight Fokker Stangensteuerung synchronization gear : 2.0 [kg]
weight armament : 40 [kg]
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weight floats : 94 [kg] (8.8 [%])
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A Albatros W.4 fighting a Short floatplane, (type 184 ?)
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calculated empty weight : 779 [kg](72.8 [%])
weight oil for 3.5 hours flying : 9.0 [kg]
weight cooling fluids : 25.0 [kg]
weight ammunition (1000 rounds) : 28.2 [kg]
weight automatic pistol with spare magazines : 1.2 [kg]
*******************************************************************
calculated operational weight empty : 843 [kg] (78.8 [%])
published operational weight empty : 790 [kg] (73.8 [%])
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weight crew : 81 [kg]
weight fuel for 2.0 hours flying : 65 [kg]
********************************************************************
operational weight : 988 [kg](92.4 [%])
estimated bomb load : 50 [kg]
operational weight bombing mission : 1038 [kg]
fuel reserve : 32 [kg] enough for 0.99 [hours] flying
operational weight fully loaded : 1070 [kg] with fuel tank filled for 90 [%]
published maximum take-off weight : 1070 [kg] (100.0 [%])
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calculation : * 4 * (engine power)
power loading (operational without bombload) : 8.13 [kg/kW]
total power : 121.5 [kW] at 1400 [r.p.m]
Later production W.4 with Teeves and Braun aerofoil-shaped radiators in the upper wing centre section.
calculation : *5* (loads)
manoeuvre load : 2.5 [g] at 1000 [m]
limit load : 3.5 [g] ultimate load : 5.2 [g] load factor : 2.2 [g]
design flight time : 2.34 [hours]
design cycles : 427 sorties, design hours : 1000 [hours]
operational wing loading : 307 [N/m^2]
wing stress (3 g) during operation : 223 [N/kg] at 3g emergency manoeuvre
calculation : *6* (angles of attack)
angle of attack zero lift : -1.29 ["]
max. angle of attack (stalling angle) : 13.14 ["]
angle of attack at max. speed : 2.00 ["]
calculation : *7* (lift & drag ratios
lift coefficient at angle of attack 0° :0.10 [ ]
lift coefficient at max. angle of attack : 1.12 [ ]
lift coefficient at max. speed : 0.26 [ ]
induced drag coefficient at max. speed : 0.0065 [ ]
drag coefficient at max. speed : 0.0450 [ ]
drag coefficient (zero lift) : 0.0385 [ ]
calculation : *8* (speeds
stalling speed at sea-level (OW): 76 [km/u]
landing speed at sea-level (OW without bombload): 91 [km/hr]
min. drag speed (max endurance) : 110 [km/hr] at 1500 [m](power :51 [%])
min. power speed (max range) : 117 [km/hr] at 1500 [m] (power:54 [%])
max. rate of climb speed : 102.1 [km/hr] at sea-level
cruising speed : 144 [km/hr] op 1500 [m] (power:72 [%])
design speed prop : 152 [km/hr]
maximum speed : 160 [km/hr] op 100 [m] (power:99 [%])
W.4 flown by Friedrich Christiansen
climbing speed at sea-level (without bombload) : 214 [m/min]
calculation : *9* (regarding various performances)
take-off distance at sea-level : 153 [m]
lift/drag ratio : 8.10 [ ]
max. practical ceiling : 4400 [m] with flying weight :910 [kg]
practical ceiling (operational weight) : 3850 [m] with flying weight :988 [kg] line 3385
practical ceiling fully loaded (mtow- 1 hour fuel) : 3500 [m] with flying weight :1038 [kg]
published ceiling (3000 [m]
climb to 1500m (operational weight without bombload) : 8.03 [min]
climb to 3000m (operational weight without bombload) : 21.41 [min]
max. dive speed : 367.2 [km/hr] at 2500 [m] height
load factor at max. angle turn 1.64 ["g"]
turn radius at 500m: 60 [m]
time needed for 360* turn 13.7 [seconds] at 500m
calculation *10* (action radius & endurance)
operational endurance : 2.99 [hours] with 1 crew and 50 [kg] useful (bomb)load and 89.8 [%] fuel
published endurance : 2.93 [hours] with 1 crew and possible useful (bomb) load : 52 [kg] and 88.1 [%] fuel
action radius : 282 [km] with 1 crew and 20[kg] photo camera or bombload
max range theoretically with additional fuel tanks for total 240 [litre] fuel : 784 [km]
useful load with action-radius 250km : 64 [kg]
production : 9.17 [tonkm/hour]
oil and fuel consumption per tonkm : 3.79 [kg]
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Literature :
fighters 1914-19 page 90
Praktisch handboek vliegtuigen deel 1 page 292
Wikipedia
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 17 May 2020 contact : info.aircraftinvestigation@gmail.com python 3.7.4