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Albatros D.II
role : fighter
first flight : operational : November 1916
country : Germany
design : Robert Thelen
production : 291 aircraft, Johannisthal near Berlin
general information : Pilots complaint about poor visibility in the D.I, so Thelen and his
team addressed this problem by lowering the top plane and give it a forward stagger.
Windhoff Ohren-kuhler on the side of the fuselage. The D.II outclassed any allied fighter at that moment it was fast and it had two Spandau machineguns each with 500 rounds giving superior fire-power. It restored German air superiority end 1916. It was soon replaced by the even better Albatros D.III.
Area upper wing : 13.5 m^2
Area lower wing : 11.5 m^2
Total wing area : 25.0 m^2
stabilo : 1.1 m^2
rudder : 0.55 m^2
wing chord : 1.62m
users : Luftwaffe
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](119.9 KW)
dimensions :
wingspan : 8.5 [m], length : 7.4 [m], height : 2.74[m]
wing area : 24.5 [m^2]
weights :
max.take-off weight : 888 [kg]
empty weight operational : 637 [kg] bombload : 0 [kg]
performance :
maximum speed : 175 [km/hr] at sea-level
climbing speed : 180 [m/min]
service ceiling : 5200 [m]
endurance : 1.5 [hours]
estimated action radius : 118 [km]
description :
1-bay biplane with fixed landing gear and tail strut
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 2.68 [m]
angle of attack prop : 18.26 [ ]
reduction : 1.00 [ ]
airscrew revs : 1400 [r.p.m.]
pitch at Max speed 2.08 [m]
blade-tip speed at Vmax and max revs. : 202 [m/s]
calculation : *1* (dimensions)
mean wing chord : 1.44 [m]
calculated wing chord (rounded tips): 1.65 [m]
wing aspect ratio : 5.90 []
estimated gap : 1.25 [m]
gap/chord : 0.87 [ ]
seize (span*length*height) : 172 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 2.5 [kg/hr]
fuel consumption(cruise speed) : 29.5 [kg/hr] (40.2 [litre/hr]) at 65 [%] power
distance flown for 1 kg fuel : 5.34 [km/kg]
estimated total fuel capacity : 69 [litre] (50 [kg])
D.II wing with steel compression bars between the spars
calculation : *3* (weight)
weight engine(s) dry : 299.0 [kg] = 2.49 [kg/KW]
weight 8 litre oil tank : 0.7 [kg]
oil tank filled with 0.9 litre oil : 0.8 [kg]
oil in engine 7 litre oil : 6.0 [kg]
fuel in engine 1 litre fuel : 0.6 [kg]
weight 17 litre gravity patrol tank(s) : 2.6 [kg]
weight radiator : 17.2 [kg]
weight exhaust pipes & fuel lines 10.5 [kg]
weight cowling 4.8 [kg]
weight airscrew(s) (wood) incl. boss & bolts : 19.0 [kg]
total weight propulsion system : 360 [kg](40.6 [%])
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***possible week construction , check weights , design hours below 250
fuselage skeleton (wood gauge : 5.20 [cm]): 51 [kg]
bracing : 2.7 [kg]
fuselage covering ( 10.3 [m2] doped linen fabric) : 3.3 [kg]
weight controls + indicators: 5.6 [kg]
weight seats : 3.0 [kg]
weight other details, lighting set, etc. : 5.1 [kg]
weight 51 [litre] main fuel tank empty : 4.1 [kg]
weight engine mounts & firewalls : 6 [kg]
total weight fuselage : 81 [kg](9.1 [%])
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weight wing covering (doped linen fabric) : 16 [kg]
total weight ribs (50 ribs) : 53 [kg]
load on front upper spar (clmax) per running metre : 621.9 [N]
load on rear upper spar (vmax) per running metre : 298.1 [N]
D.II met Windhoff “ear”-radiators.
In November 1916, Idflieg banned Windhoff "ear" radiators in operational aircraft because they were at a lower level than the crankcase of the engine they were cooling, and a shot into either radiator was likely to drain the cooling system. Late production D.IIs switched to using a Teves und Braun "airfoil shape" radiator (the Teves company still exists in the 21st century), in the center section of the upper wing. This also proved to be a problematic as a leaking or battle damaged radiator could scald the pilot's face. On later Albatros fighters (late models of the D.III, and the D.V) the radiator was moved to the right of the center section to alleviate this problem.
total weight 8 spars : 26 [kg]
weight wings : 94 [kg]
weight wing/square meter : 3.85 [kg]
weight 4 interplane struts & cabane : 5.5 [kg]
weight cables (42 [m]) : 1.7 [kg] (= 41 [gram] per metre)
diameter cable : 2.6 [mm]
weight fin & rudder (0.8 [m2]) : 3.4 [kg]
weight stabilizer & elevator (2.8 [m2]): 10.8 [kg]
total weight wing surfaces & bracing : 116 [kg] (13.0 [%])
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weight machine-gun(s) : 34.0 [kg]
weight ammunition magazine(s) :3.5 [kg]
weight synchronizing system : 2.0 [kg]
weight armament : 40 [kg]
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wheel pressure : 444.0 [kg]
weight 2 wheels (790 [mm] by 100 [mm]) : 21.2 [kg]
weight tailskid : 1.6 [kg]
weight undercarriage with axle 14.3 [kg]
total weight landing gear : 37.1 [kg] (4.2 [%]
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Minutes before take-off – Albatros D.II of Jasta 9 end of February 1917 at Leffincourt Airfield, about 40Km north-east of Reims.
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calculated empty weight : 634 [kg](71.4 [%])
weight oil for 1.8 hours flying : 4.5 [kg]
weight cooling fluids : 25.9 [kg]
weight ammunition (1000 rounds) : 35.0 [kg]
weight signal pistol with cartridges : 3.6 [kg]
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calculated operational weight empty : 703 [kg] (79.1 [%])
published operational weight empty : 637 [kg] (71.7 [%])
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weight crew : 81 [kg]
weight fuel for 1.5 hours flying : 44 [kg]
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operational weight : 828 [kg](93.2 [%])
estimated bomb load : 25 [kg]
operational weight bombing mission : 853 [kg]
fuel reserve : 6 [kg] enough for 0.20 [hours] flying
possible additional useful load : 29 [kg]
operational weight fully loaded : 888 [kg] with fuel tank filled for 100 [%]
published maximum take-off weight : 888 [kg] (100.0 [%])
D.II model. The fuel tanks are placed directly behind the engine. Behind the fuel tanks the cartridge holders for the twin Spandau machine guns are visible.
The fuselage was shaped by 3/8-in ply formers connected by 6 spruce longerons allong the length. Attached to it was a plywood skin.
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calculation : * 4 * (engine power)
power loading (operational without bombload) : 6.91 [kg/kW]
total power : 119.9 [kW] at 1400 [r.p.m]
calculation : *5* (loads)
manoeuvre load : 2.8 [g] at 1000 [m]
limit load : 4.5 [g] ultimate load : 6.8 [g] load factor : 1.6 [g]
design flight time : 1.20 [hours]
design cycles : 187 sorties, design hours : 225 [hours]
operational wing loading : 331 [N/m^2]
wing stress (3 g) during operation : 259 [N/kg] at 3g emergency manoeuvre
calculation : *6* (angles of attack)
angle of attack zero lift : -1.27 ["]
max.angle of attack (stalling angle) : 13.07 ["]
angle of attack at max.speed : 1.67 ["]
calculation : *7* (lift & drag ratios
lift coefficient at angle of attack 0° :0.10 [ ]
lift coefficient at max. angle of attack : 1.13 [ ]
lift coefficient at max.speed : 0.23 [ ]
induced drag coefficient at max.speed : 0.0051 [ ]
drag coefficient at max.speed : 0.0438 [ ]
drag coefficient (zero lift) : 0.0387 [ ]
calculation : *8* (speeds
stalling speed at sea-level (OW): 79 [km/u]
landing speed at sea-level (OW without bombload): 95 [km/hr]
min.drag speed (max endurance) : 119 [km/hr] at 2600 [m](power :47 [%])
min. power speed (max range) : 128 [km/hr] at 2600 [m] (power:50 [%])
max.rate of climb speed : 109.2 [km/hr] at sea-level
cruising speed : 158 [km/hr] op 2600 [m] (power:66 [%])
design speed prop : 170 [km/hr]
maximum speed : 175 [km/hr] op 100 [m] (power:99 [%])
climbing speed at sea-level (without bombload) : 266 [m/min]
calculation : *9* (regarding various performances)
take-off distance at sea-level : 162 [m]
lift/drag ratio : 8.21 [ ]
max. practical ceiling : 5125 [m] with flying weight :760 [kg]
practical ceiling (operational weight): 4550 [m] with flying weight :828 [kg]
practical ceiling fully loaded (mtow- 1 hour fuel) : 4300 [m] with flying weight :858 [kg]
published ceiling (5200 [m]
climb to 1500m (without bombload) : 6.34 [min]
climb to 3000m (without bombload) : 16.02 [min]
max.dive speed : 394.0 [km/hr] at 3300 [m] height
load factor at max.angle turn 1.79 ["g"]
turn radius at 500m: 62 [m]
time needed for 360* turn 13.0 [seconds] at 500m
calculation *10* (action radius & endurance)
operational endurance : 1.70 [hours] with 1 crew and 54 [kg] useful (bomb)load and 100.0 [%] fuel
published endurance : 1.50 [hours] with 1 crew and possible useful (bomb) load : 60 [kg] and 88.1 [%] fuel
action radius : 225 [km] with 1 crew and 20[kg] photo camera/radio transmitter or bombload
max range theoretically with additional fuel tanks for total 195 [litre] fuel : 763 [km]
useful load with action-radius 250km : 49 [kg]
production : 7.76 [tonkm/hour]
oil and fuel consumption per tonkm : 4.13 [kg]
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notes : design hours is very low with 225 hrs, indication for week construction
Literature :
Fighters 1914-19 page 38
Praktisch handboek vliegtuigen deel 1 page 261
Warplanes WOI page 56,62,87
Jane’s fighting aircraft WWI page 140,141
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.
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(c) B van der Zalm 04 January 2019 contact : info.aircraftinvestigation@gmail.com python 3.7.2(32-bit)