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weight and performance calculations for the DFW B.I
DFW B.I
role : two-seat unarmed reconnaissance
importance : ***
first flight : Summer 1914 operational : August 1914
country : Germany
design :
production : ca. 50 aircraft
general information :
DFW built the famous Taube before the start of WOI. In the design of the B.I (Factory designation MD14), you can see the influence of the Taube back in the banana-shaped wing. This earned the device the nickname "flying Banana". It was a stable and enjoyable flying plane. Striking were the H.&Z.cooling radiators along the hull and the exhausts pointing to below. At the beginning of WOI, the aircraft was quickly taken into military service, referred to as B.I. With the arrival of armed 2-seaters scouts in 1915, the aircraft was pulled back from the front and then deployed as a training aircraft.
B.I with registration B.451/14 was brought down on November 18, 1914 near Albert-Bapaume by Sgt Eugene Gilbert and soldier Bayle of Escadrille Ms.23 in Reims flying a Morane Saulnier type L. The DFW had to make an emergency landing in French territory and the crew was captured. Plane was shown to the public in Paris in the army museum. (Musee de l’armee). The Morane Parasol had max speed of 115 km/u and a practical ceiling with 2 crew of 3225m so it must not have been all to easy to intercept the DFW. The Parasol had a higher climbing speed : 176m/min compared to 147 m/min for the DFW B.I
users : Germany
crew : 2 (observer in front, pilot in back seat)
armament : no fixed armament
engine : 1 Mercedes D.I liquid-cooled 6 -cylinder inline engine 100 [hp](73.6 KW)
dimensions :
wingspan : 14.0 [m], length : 8.38 [m], height : 2.99[m]
wing area : 40.0 [m^2]
weights :
max.take-off weight : 1019 [kg]
empty weight operational (estimation): 685.0 [kg] bombload : 50 [kg]
performance :
maximum speed : 120 [km/hr] at sea-level
service ceiling : 3000 [m]
endurance : 4.0 [hours]
estimated action radius : 216 [km]
description :
3-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 :0.62 [ ]
estimated diameter airscrew 2.57 [m]
angle of attack prop : 16.03 [ ]
reduction : 1.00 [ ]
airscrew revs : 1150 [r.p.m.]
pitch at Max speed 1.74 [m]
blade-tip speed at Vmax and max revs. : 158 [m/s]
calculation : *1* (dimensions)
mean wing chord : 1.43 [m]
calculated wing chord (rounded tips): 1.55 [m]
wing aspect ratio : 9.80 []
estimated gap : 1.89 [m]
gap/chord : 1.32 [ ]
seize (span*length*height) : 351 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 1.7 [kg/hr]
fuel consumption(cruise speed) : 23.4 [kg/hr] (32.0 [litre/hr]) at 73 [%] 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 : 191.2 [kg] = 2.60 [kg/KW]
weight 11 litre oil tank : 0.9 [kg]
oil tank filled with 0.6 litre oil : 0.5 [kg]
oil in engine 4 litre oil : 3.7 [kg]
fuel in engine 1 litre fuel : 0.4 [kg]
weight 14 litre gravity patrol tank(s) : 2.0 [kg]
weight radiator : 10.5 [kg]
weight exhaust pipes & fuel lines 9.0 [kg]
weight cowling 2.9 [kg]
weight airscrew(s) (wood) incl. boss & bolts : 16.9 [kg]
total weight propulsion system : 237 [kg](23.3 [%])
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fuselage skeleton (wood gauge : 6.97 [cm]): 104 [kg]
bracing : 6.2 [kg]
fuselage covering ( 13.3 [m2] doped linen fabric) : 4.2 [kg]
weight controls + indicators: 6.6 [kg]
weight seats : 6.0 [kg]
weight other details, lighting set, etc. : 5.1 [kg]
weight bomb storage : 3.5 [kg]
weight 132 [litre] main fuel tank empty : 10.5 [kg]
weight engine mounts & firewalls : 4 [kg]
total weight fuselage : 150 [kg](14.7 [%])
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weight wing covering (doped linen fabric) : 26 [kg]
total weight ribs (58 ribs) : 61 [kg]
load on front upper spar (clmax) per running metre : 657.5 [N]
load on rear upper spar (vmax) per running metre : 201.0 [N]
total weight 8 spars : 74 [kg]
weight wings : 160 [kg]
weight wing/square meter : 4.00 [kg]
weight 12 interplane struts & cabane : 37.9 [kg]
weight cables (98 [m]) : 11.4 [kg] (= 116 [gram] per metre)
diameter cable : 4.4 [mm]
weight fin & rudder (2.3 [m2]) : 9.4 [kg]
weight stabilizer & elevator (4.5 [m2]): 18.3 [kg]
total weight wing surfaces & bracing : 237 [kg] (23.3 [%])
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weight armament : 0 [kg]
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wheel pressure : 509.5 [kg]
weight 2 wheels (790 [mm] by 100 [mm]) : 25.2 [kg]
weight tailskid : 2.9 [kg]
weight undercarriage with axle 23.6 [kg]
total weight landing gear : 51.7 [kg] (5.1 [%]
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“captured aviatik Paris” > but it was a DFW, an example for that at the start of WWI every German 2-seater biplane was referred to as Aviatik and all German monoplanes were Taubes.
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calculated empty weight : 676 [kg](66.3 [%])
weight oil for 4.8 hours flying : 8.1 [kg]
weight cooling fluids : 15.9 [kg]
weight automatic pistol with spare magazines : 1.2 [kg]
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calculated operational weight empty : 701 [kg] (68.8 [%])
estimated operational weight empty : 685 [kg] (67.2 [%])
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weight crew : 162 [kg]
weight fuel for 2.0 hours flying : 47 [kg]
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operational weight : 910 [kg](89.3 [%])
bomb load : 50 [kg]
operational weight bombing mission : 960 [kg]
weight camera : 20 [kg]
operational weight photo mission : 930 [kg]
fuel reserve : 60 [kg] enough for 2.54 [hours] flying
possible additional useful load : 29 [kg]
operational weight fully loaded : 1019 [kg] with fuel tank filled for 100 [%]
published maximum take-off weight : 1019 [kg] (100.0 [%])
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calculation : * 4 * (engine power)
power loading (operational without bombload) : 12.37 [kg/kW]
total power : 73.6 [kW] at 1150 [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 : 2.5 [g]
design flight time : 3.20 [hours]
design cycles : 406 sorties, design hours : 1300 [hours]
operational wing loading : 228 [N/m^2]
wing stress (3 g) during operation : 171 [N/kg] at 3g emergency manoeuvre
calculation : *6* (angles of attack)
angle of attack zero lift : -1.12 ["]
max. angle of attack (stalling angle) : 11.47 ["]
angle of attack at max. speed : 2.58 ["]
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 : 0.33 [ ]
induced drag coefficient at max. speed : 0.0063 [ ]
drag coefficient at max. speed : 0.0503 [ ]
drag coefficient (zero lift) : 0.0440 [ ]
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) : 79 [km/hr] at 1500 [m](power :47 [%])
min. power speed (max range) : 90 [km/hr] at 1500 [m] (power:53 [%])
max. rate of climb speed : 75.2 [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) : 147 [m/min]
calculation : *9* (regarding various performances)
take-off distance at sea-level : 204 [m]
lift/drag ratio : 9.92 [ ]
max. practical ceiling : 4350 [m] with flying weight :793 [kg]
practical ceiling (operational weight): 3525 [m] with flying weight :910 [kg]
practical ceiling fully loaded (mtow- 1 hour fuel) : 2950 [m] with flying weight :996 [kg]
published ceiling (3000 [m]
climb to 1500m (without bombload) : 11.76 [min]
DFW B.I reg.nr. B.451/12 wrongly indicated as a Taube
max. dive speed : 313.5 [km/hr] at 1950 [m] height
load factor at max. angle turn 1.75 ["g"]
turn radius at 500m: 43 [m]
time needed for 360* turn 11.0 [seconds] at 500m
calculation *10* (action radius & endurance)
operational endurance : 4.51 [hours] with 2 crew and 50 [kg] useful (bomb)load and 99.4 [%] fuel
published endurance : 4.00 [hours] with 2 crew and possible useful (bomb) load : 62 [kg] and 88.1 [%] fuel
action radius : 313 [km] with 2 crew and 20[kg] photo camera/radio transmitter or bombload
max range theoretically with additional fuel tanks for total 325 [litre] fuel : 1097 [km]
useful load with action-radius 250km : 129 [kg]
production : 13.98 [tonkm/hour]
oil and fuel consumption per tonkm : 1.80 [kg]
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literature :
Praktisch handboek vliegtuigen deel 1 page 248
Jane’s fighting aircraft WOI page 146f
German aircraft of the first world war page 317
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