AIRCRAFT INVESTIGATION
weight and performance calculations for the Albatros B.IIa WWI primary trainer
Albatros B.IIa that was interned by the Swedish air force
Albatros B.IIa
role : two-seat unarmed reconnaissance and primary trainer
importance : ***
first flight : operational : February 1915
country : Germany
design :
production : 600 aircraft
general information :
Version with more powerful 120 hp engine, and stronger tail construction. Because of its fine flight characteristics and robustness also used a lot as a trainer. It was also equipped with dual controls. In addition to the Mercedes engine, many B.IIa were equipped with a Argus As.II engine
users : Luftwaffe, Sweden, Poland
crew : 2
armament : no fixed armament
engine : 1 Argus As.II liquid-cooled 6 -cylinder inline engine 120 [hp](88.3 KW) or 120
[hp] Mercedes D.II
dimensions :
wingspan : 12.8 [m], length : 7.63 [m], height : 3.15[m]
wing area : 40.12 [m^2]
weights :
max.take-off weight : 1078 [kg]
empty weight operational : 723 [kg] bombload : 0 [kg]
performance :
maximum speed : 120 [km/hr] at sea-level
climbing speed : 96 [m/min]
service ceiling : 3000 [m]
endurance : 4.0 [hours]
estimated action radius : 216 [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
Albatros B.IIa of the Polish Air Force, they used the B.IIA as a trainer until 1927. At the B.IIa, the radiators were no longer attached to the side of the fuselage but to the upper wing leading edge.
airscrew :
fixed pitch 2 -bladed tractor airscrew with max. efficiency :0.63 [ ]
estimated diameter airscrew 2.77 [m]
angle of attack prop : 12.79 [ ]
fine pitch
reduction : 1.00 [ ]
airscrew revs : 1350 [r.p.m.]
pitch at Max speed 1.48 [m]
blade-tip speed at Vmax and max revs. : 199 [m/s]
calculation : *1* (dimensions)
mean wing chord : 1.57 [m]
calculated wing chord (rounded tips): 1.72 [m]
wing aspect ratio : 8.17 []
estimated gap : 1.70 [m]
gap/chord : 1.08 [ ]
seize (span*length*height) : 308 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 1.9 [kg/hr]
fuel consumption(cruise speed) : 23.4 [kg/hr] (32.0 [litre/hr]) at 72 [%] power
distance flown for 1 kg fuel : 4.61 [km/kg]
estimated total fuel capacity : 145 [litre] (106 [kg])
calculation : *3* (weight)
weight engine(s) dry : 211.8 [kg] = 2.40 [kg/KW]
weight 13 litre oil tank : 1.1 [kg]
oil tank filled with 0.7 litre oil : 0.6 [kg]
Clearly the installation of the radiator to the wing leading edge can be seen
oil in engine 5 litre oil : 4.4 [kg]
fuel in engine 1 litre fuel : 0.4 [kg]
weight 14 litre gravity patrol tank(s) : 2.0 [kg]
weight radiator : 12.6 [kg]
weight exhaust pipes & fuel lines 10.7 [kg]
weight cowling 3.5 [kg]
weight airscrew(s) (wood) incl. boss & bolts : 19.0 [kg]
total weight propulsion system : 265 [kg](24.6 [%])
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fuselage skeleton (wood gauge : 7.82 [cm]): 119 [kg]
bracing : 6.4 [kg]
fuselage covering ( 11.0 [m2] doped linen fabric) : 3.5 [kg]
weight dual controls + indicators: 13.2 [kg]
weight seats : 6.0 [kg]
weight other details, lighting set, etc. : 5.1 [kg]
weight 132 [litre] main fuel tank empty : 10.5 [kg]
weight engine mounts & firewalls : 4 [kg]
total weight fuselage : 168 [kg](15.6 [%])
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weight wing covering (doped linen fabric) : 26 [kg]
total weight ribs (56 ribs) : 64 [kg]
load on front upper spar (clmax) per running metre : 743.7 [N]
load on rear upper spar (vmax) per running metre : 229.8 [N]
total weight 8 spars : 70 [kg]
weight wings : 160 [kg]
weight wing/square meter : 3.98 [kg]
weight 8 interplane struts & cabane : 23.8 [kg]
weight cables (75 [m]) : 8.2 [kg] (= 110 [gram] per metre)
diameter cable : 4.2 [mm]
weight fin & rudder (1.9 [m2]) : 7.8 [kg]
weight stabilizer & elevator (4.5 [m2]): 18.3 [kg]
total weight wing surfaces & bracing : 218 [kg] (20.2 [%])
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weight armament : 0 [kg]
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wheel pressure : 539.0 [kg]
weight 2 wheels (750 [mm] by 99 [mm]) : 26.7 [kg]
weight tailskid : 3.6 [kg]
weight undercarriage with axle 27.9 [kg]
total weight landing gear : 58.2 [kg] (5.4 [%]
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calculated empty weight : 710 [kg](65.8 [%])
weight oil for 4.8 hours flying : 9.3 [kg]
weight cooling fluids : 19.1 [kg]
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calculated operational weight empty : 738 [kg] (68.5 [%])
published operational weight empty : 723 [kg] (67.1 [%])
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weight crew : 162 [kg]
weight fuel for 2.0 hours flying : 47 [kg]
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operational weight : 947 [kg](87.8 [%])
estimated bomb load : 50 [kg]
operational weight bombing mission : 997 [kg]
fuel reserve : 60 [kg] enough for 2.54 [hours] flying
possible additional useful load : 22 [kg]
operational weight fully loaded : 1078 [kg] with fuel tank filled for 100 [%]
published maximum take-off weight : 1078 [kg] (100.0 [%])
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calculation : * 4 * (engine power)
power loading (operational without bombload) : 10.73 [kg/kW]
total power : 88.3 [kW] at 1350 [r.p.m]
calculation : *5* (loads)
manoeuvre load : 1.9 [g] at 1000 [m]
limit load : 3.75 [g] ultimate load : 5.6 [g] load factor : 2.4 [g]
design flight time : 1.60 [hours]
design cycles : 562 sorties, design hours : 900 [hours]
operational wing loading : 231 [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 : -1.16 ["]
max. angle of attack (stalling angle) : 12.16 ["]
angle of attack at max. speed : 2.83 ["]
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 : 0.34 [ ]
induced drag coefficient at max. speed : 0.0082 [ ]
drag coefficient at max. speed : 0.0605 [ ]
drag coefficient (zero lift) : 0.0523 [ ]
calculation : *8* (speeds
stalling speed at sea-level (OW): 65 [km/u]
landing speed at sea-level (OW without bombload): 78 [km/hr]
min. drag speed (max endurance) : 81 [km/hr] at 1500 [m](power :49 [%])
min. power speed (max range) : 92 [km/hr] at 1500 [m] (power:55 [%])
max. rate of climb speed : 75.9 [km/hr] at sea-level
cruising speed : 108 [km/hr] op 1500 [m] (power:71 [%])
design speed prop : 114 [km/hr]
maximum speed : 120 [km/hr] op 100 [m] (power:99 [%])
climbing speed at sea-level (without bombload) : 166 [m/min]
calculation : *9* (regarding various performances)
take-off distance at sea-level : 134 [m]
lift/drag ratio : 8.30 [ ]
max. practical ceiling : 3900 [m] with flying weight :831 [kg]
practical ceiling (operational weight): 3200 [m] with flying weight :947 [kg]
practical ceiling fully loaded (mtow- 1 hour fuel) : 2575 [m] with flying weight :1055 [kg]
published ceiling (3000 [m]
climb to 1500m (without bombload) : 10.61 [min]
max. dive speed : 276.4 [km/hr] at 1575 [m] height
load factor at max. angle turn 1.72 ["g"]
turn radius at 500m: 43 [m]
time needed for 360* turn 11.1 [seconds] at 500m
calculation *10* (action radius & endurance)
operational endurance : 4.54 [hours] with 2 crew and 72 [kg] useful (bomb)load and 100.0 [%] fuel
published endurance : 4.00 [hours] with 2 crew and possible useful (bomb) load : 84 [kg] and 88.1 [%] fuel
action radius : 364 [km] with 2 crew and 20[kg] photo camera/radio transmitter or bombload
max range theoretically with additional fuel tanks for total 353 [litre] fuel : 1193 [km]
useful load with action-radius 250km : 150 [kg]
production : 16.25 [tonkm/hour]
oil and fuel consumption per tonkm : 1.56 [kg]
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Literature :
Bombers 1914-19 page 109
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 23 November 2019 contact : info.aircraftinvestigation@gmail.com python 3.7.4