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weight and performance calculations for the Aviatik B.II

Aviatik B.II built by the Automobil und Aviatik-werke in Leipzig.

Not to be confused with the Austro-Hungarian Aviatik B.II series 32. Note the different tail fin and also the German B.II had no slanted struts supporting the upper wing tips.

Aviatik B.II

role : two-seat unarmed reconnaissance

importance : ***

first flight : operational : April 1915

country : Germany

design : Robert Wild

production : unknown, Automobil und Aviatik-werke in Leipzig

general information :

Not to be confused with the Austro-Hungarian Aviatik B.II series 32 and 34 which were different aircraft.

It had a more powerful engine with a single "rhino horn" collector stack for the exhaust. Originally no armament was fitted but later production aircraft received a machine gun for the observer. The observer was still in the forward seat, with the pilot sitting behind, and his field of view and fire was limited by the wings. Not to much B.II were built, it was soon replaced on the production line by the Aviatik C.I which was armed but much the same in appearance. All aircraft were withdrawn from front line service in 1916 and then continued in use as a trainer. It was used in this role by FEA9 in Darmstadt (Griesheimer Sand flugplatz).

users : Germany

crew : 2

armament : no fixed armament

engine : 1 Mercedes D.II liquid-cooled 6 -cylinder inline engine 120 [hp](89.5 KW)

dimensions :

wingspan : 12.49 [m], length : 7.1 [m], height : 3.15[m]

wing area : 41.0 [m^2]

weights :

max.take-off weight : 1071 [kg]

empty weight operational : 670 [kg] bombload : 75 [kg]

performance :

maximum speed : 100 [km/hr] at sea-level

service ceiling : 3200 [m]

endurance : 4.0 [hours]

estimated action radius : 180 [km]

description :

2-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 2.32 [m]

angle of attack prop : 12.29 [ ]

fine pitch

Note the different exhaust pipes

reduction : 1.00 [ ]

airscrew revs : 1400 [r.p.m.]

pitch at Max speed 1.19 [m]

blade-tip speed at Vmax and max revs. : 172 [m/s]

calculation : *1* (dimensions)

mean wing chord : 1.64 [m]

calculated wing chord (rounded tips): 1.81 [m]

wing aspect ratio : 7.61 []

estimated gap : 1.67 [m]

gap/chord : 1.02 [ ]

seize (span*length*height) : 279 [m^3]

calculation : *2* (fuel consumption)

oil consumption : 2.1 [kg/hr]

fuel consumption(cruise speed) : 23.5 [kg/hr] (32.1 [litre/hr]) at 72 [%] power

distance flown for 1 kg fuel : 3.82 [km/kg]

estimated total fuel capacity : 146 [litre] (107 [kg])

calculation : *3* (weight)

weight engine(s) dry : 204.0 [kg] = 2.28 [kg/KW]

weight 13 litre oil tank : 1.7 [kg]

oil tank filled with 0.7 litre oil : 0.6 [kg]

oil in engine 5 litre oil : 4.5 [kg]

fuel in engine 1 litre fuel : 0.4 [kg]

weight 14 litre gravity patrol tank(s) : 1.3 [kg]

weight radiator : 12.8 [kg]

weight exhaust pipes & fuel lines 11.5 [kg]

weight cowling 3.6 [kg]

weight airscrew(s) (wood) incl. boss & bolts : 19.0 [kg]

total weight propulsion system : 258 [kg](24.1 [%])

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fuselage skeleton (wood gauge : 6.93 [cm]): 87 [kg]

bracing : 4.4 [kg]

fuselage covering ( 9.5 [m2] doped linen fabric) : 3.0 [kg]

weight controls + indicators: 6.1 [kg]

weight seats : 6.0 [kg]

weight other details, lighting set, etc. : 5.1 [kg]

This is a German Aviatik B.II, very similar to its successor the armed Aviatik C.I. It was built by the German Automobil und Aviatik-fabrik in Leipzig.

weight bomb storage : 5.3 [kg]

weight 132 [litre] main fuel tank empty : 12.7 [kg]

weight engine mounts & firewalls : 4 [kg]

total weight fuselage : 134 [kg](12.5 [%])

***************************************************************

weight wing covering (doped linen fabric) : 26 [kg]

total weight ribs (53 ribs) : 64 [kg]

load on front upper spar (clmax) per running metre : 709.9 [N]

load on rear upper spar (vmax) per running metre : 230.8 [N]

total weight 8 spars : 63 [kg]

weight wings : 153 [kg]

weight wing/square meter : 3.74 [kg]

weight 8 interplane struts & cabane : 21.8 [kg]

weight cables (73 [m]) : 7.3 [kg] (= 100 [gram] per metre)

diameter cable : 4.0 [mm]

weight fin & rudder (1.8 [m2]) : 7.0 [kg]

weight stabilizer & elevator (4.6 [m2]): 17.6 [kg]

total weight wing surfaces & bracing : 207 [kg] (19.3 [%])

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weight armament : 0 [kg]

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wheel pressure : 535.5 [kg]

weight 2 wheels (700 [mm] by 84 [mm]) : 22.9 [kg]

weight tailskid : 2.8 [kg]

weight undercarriage with axle 26.9 [kg]

total weight landing gear : 52.7 [kg] (4.9 [%]

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Pilot und Fluglehrer Hans Dieckmann (Jg.1894) vor seiner Maschine im März 1916 in Griesheim.

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calculated empty weight : 652 [kg](60.9 [%])

weight oil for 4.8 hours flying : 9.9 [kg]

weight cooling fluids : 18.4 [kg]

weight automatic pistol with spare magazines : 1.2 [kg]

*******************************************************************

calculated operational weight empty : 681 [kg] (63.6 [%])

published operational weight empty : 670 [kg] (62.6 [%])

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weight crew : 162 [kg]

weight fuel for 2.0 hours flying : 47 [kg]

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operational weight : 890 [kg](83.1 [%])

bomb load : 75 [kg]

operational weight bombing mission : 965 [kg]

weight camera : 20 [kg]

operational weight photo mission : 910 [kg]

fuel reserve : 60 [kg] enough for 2.54 [hours] flying

possible additional useful load : 101 [kg]

operational weight fully loaded : 1071 [kg] with fuel tank filled for 100 [%]

published maximum take-off weight : 1071 [kg] (100.0 [%])

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calculation : * 4 * (engine power)

power loading (operational without bombload) : 9.95 [kg/kW]

total power : 89.5 [kW] at 1400 [r.p.m]

calculation : *5* (loads)

manoeuvre load : 1.4 [g] at 1000 [m]

limit load : 3.75 [g] ultimate load : 5.6 [g] load factor : 2.3 [g]

design flight time : 3.20 [hours]

design cycles : 359 sorties, design hours : 1150 [hours]

operational wing loading : 218 [N/m^2]

wing stress (3 g) during operation : 175 [N/kg] at 3g emergency manoeuvre

calculation : *6* (angles of attack)

angle of attack zero lift : -1.18 ["]

max. angle of attack (stalling angle) : 12.39 ["]

angle of attack at max. speed : 4.20 ["]

calculation : *7* (lift & drag ratios

lift coefficient at angle of attack 0° :0.10 [ ]

lift coefficient at max. angle of attack : 1.15 [ ]

lift coefficient at max. speed : 0.45 [ ]

induced drag coefficient at max. speed : 0.0154 [ ]

drag coefficient at max. speed : 0.1038 [ ]

drag coefficient (zero lift) : 0.0885 [ ]

calculation : *8* (speeds

stalling speed at sea-level (OW): 63 [km/u]

landing speed at sea-level (OW without bombload): 75 [km/hr]

min. drag speed (max endurance) : 75 [km/hr] at 1600 [m](power :55 [%])

Aviatik B II No. B 558 / 15 landed near Hangest-en-Santerre, south-east of Amiens, following engine problems, on August 28, 1915. The crew was taken prisoner by cuirassiers passing through the area. In fact, you can see these riders patrolling around the aircraft. Photo Paul Cottave-Claudet transmitted by his grandson Jean-Paul Milliand whom I thank for his help.

min. power speed (max range) : 75 [km/hr] at 1600 [m] (power:55 [%])

max. rate of climb speed : 63.9 [km/hr] at sea-level

cruising speed : 90 [km/hr] op 1600 [m] (power:72 [%])

design speed prop : 95 [km/hr]

maximum speed : 100 [km/hr] op 100 [m] (power:99 [%])

climbing speed at sea-level (without bombload) : 172 [m/min]

calculation : *9* (regarding various performances)

take-off distance at sea-level : 208 [m]

lift/drag ratio : 6.17 [ ]

max. practical ceiling : 4150 [m] with flying weight :773 [kg]

practical ceiling (operational weight) : 3250 [m] with flying weight :890 [kg] line 3385

practical ceiling fully loaded (mtow- 1 hour fuel) : 2125 [m] with flying weight :1047 [kg]

published ceiling (3200 [m]

climb to 1500m (operational weight without bombload) : 10.15 [min]

max. dive speed : 221.8 [km/hr] at 1125 [m] height

load factor at max. angle turn 1.57 ["g"]

turn radius at 500m: 43 [m]

time needed for 360* turn 11.9 [seconds] at 500m

calculation *10* (action radius & endurance)

operational endurance : 4.54 [hours] with 2 crew and 121 [kg] useful (bomb)load and 100.0 [%] fuel

published endurance : 4.00 [hours] with 2 crew and possible useful (bomb) load : 134 [kg] and 88.1 [%] fuel

action radius : 397 [km] with 2 crew and 20[kg] photo camera or bombload

max range theoretically with additional fuel tanks for total 423 [litre] fuel : 1185 [km]

useful load with action-radius 250km : 179 [kg]

production : 16.12 [tonkm/hour]

oil and fuel consumption per tonkm : 1.59 [kg]

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Literature :

German aircraft of the first world war page 279

Praktisch handbook vliegtuigen deel 1 page 297

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

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(c) B van der Zalm 28 June 2020 contact : info.aircraftinvestigation@gmail.com python 3.7.4