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weight and performance calculations for the Fokker D.III
Fokker D.III
role : fighter
importance : ***
first flight : operational : September 1916
country : Germany
design : Martin Kreutzer
production : 210 aircraft at Schwerin till spring 1917
general information :
Further development of D.II by installing a double-row Oberursel rotary engine. It was the last Fokker aircraft using wing warping for roll control. Fokker designation M.19. The prototype was tested on 20 July 1916 at Adlershof and following this, production aircraft were ordered. First production aircraft were delivered 1 September 1916 to Jagdstaffel 2 at Bertincourt. Oswald Boelcke received serial 352/16 and with this aircraft he succeeded in downing 7 enemy aircraft between 02 September and 15 September ! Despite this success Boelcke judged the aircraft to slow. Also the aircraft was plagued with engine trouble. The rear row of cylinders tended to overhead. Low compression gave poor performance at altitude and the engine wore out quickly. On Boelcke’s recommendations the D.III was withdrawn from the heavy battled sectors and moved to more quiet area’s. In November 1916 it was discovered that the D.III had been built not according to strength quality standards. Fokker was reprimanded but allowed to continue production. With the given empty weight 452 kg and engine weight of 204 kgs only a light and fragile construction was possible…In October 1917 Germany supplied 10 D.III to the Netherlands which were in use by the Luchtvaartafdeling till 1921.
Boelcke’s D.III 352/16 survived WOI and was displayed at the Zeughaus Museum in Berlin but it was destroyed during an allied bombing raid in 1943.
users : Luftwaffe, The Netherlands (10)
crew : 1
armament : 2 synchronized 7.92 [mm] (0.312 in) Spandau LMG 08/15 machine-guns
engine : 1 Oberursel U.III air-cooled 14 -cylinder atmospheric inlet-valve rotary engine 160 [hp]
(117.7 KW)
dimensions :
wingspan : 9.05 [m], length : 6.3 [m], height : 2.55[m]
wing area : 20.0 [m^2]
weights :
max.take-off weight : 710 [kg]
empty weight operational : 452 [kg] bombload : 0 [kg]
performance :
maximum speed : 160 [km/hr] at sea-level
climbing speed : 288 [m/min]
service ceiling : 4700 [m]
endurance : 2.0 [hours]
estimated action radius : 144 [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 2.49 [m]
angle of attack prop : 20.75 [ ]
reduction : 1.00 [ ]
airscrew revs : 1200 [r.p.m.]
pitch at Max speed 2.22 [m]
blade-tip speed at Vmax and max revs. : 163 [m/s]
calculation : *1* (dimensions)
mean wing chord : 1.10 [m]
calculated wing chord (rounded tips): 1.23 [m]
wing aspect ratio : 8.19 []
estimated gap : 1.15 [m]
gap/chord : 1.04 [ ]
seize (span*length*height) : 145 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 10.6 [kg/hr]
fuel consumption(cruise speed) : 34.8 [kg/hr] (47.4 [litre/hr]) at 61 [%] power
distance flown for 1 kg fuel : 4.14 [km/kg]
estimated total fuel capacity : 108 [litre] (79 [kg])
calculation : *3* (weight)
weight engine(s) dry : 203.6 [kg] = 1.73 [kg/KW]
weight 31 litre oil tank : 3.9 [kg]
oil tank filled with 0.9 litre oil : 0.8 [kg]
oil in engine 1 litre oil : 0.6 [kg]
fuel in engine 1 litre fuel : 0.6 [kg]
weight 20 litre gravity patrol tank(s) : 2.0 [kg]
weight cowling 4.7 [kg]
weight airscrew(s) (wood) incl. boss & bolts : 19.0 [kg]
total weight propulsion system : 231 [kg](32.6 [%])
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fuselage skeleton (wood gauge : 4.24 [cm]): 29 [kg]
bracing : 1.3 [kg]
fuselage covering ( 7.5 [m2] doped linen fabric) : 2.4 [kg]
weight controls + indicators: 5.4 [kg]
weight seats : 3.0 [kg]
weight other details, lighting set, etc. : 5.1 [kg]
weight 87 [litre] main fuel tank empty : 8.4 [kg]
weight engine mounts & firewalls : 6 [kg]
total weight fuselage : 60 [kg](8.5 [%])
***************************************************************
weight wing covering (doped linen fabric) : 13 [kg]
total weight ribs (53 ribs) : 42 [kg]
load on front upper spar (clmax) per running metre : 401.4 [N]
load on rear upper spar (vmax) per running metre : 231.1 [N]
total weight 8 spars : 19 [kg]
weight wings : 74 [kg]
weight wing/square meter : 3.69 [kg]
weight 8 interplane struts & cabane : 4.5 [kg]
weight cables (52 [m]) : 1.5 [kg] (= 30 [gram] per metre)
diameter cable : 2.2 [mm]
weight fin & rudder (1.0 [m2]) : 3.7 [kg]
weight stabilizer & elevator (2.2 [m2]): 8.5 [kg]
total weight wing surfaces & bracing : 92 [kg] (13.0 [%])
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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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wheel pressure : 355.0 [kg]
weight 2 wheels (740 [mm] by 89 [mm]) : 15.8 [kg]
weight tailskid : 1.1 [kg]
weight undercarriage with axle 9.3 [kg]
total weight landing gear : 26.1 [kg] (3.7 [%]
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calculated empty weight : 449 [kg](63.3 [%])
weight oil for 2.4 hours flying : 25.4 [kg]
weight ammunition (1000 rounds) : 28.2 [kg]
weight automatic pistol with spare magazines : 1.2 [kg]
*******************************************************************
calculated operational weight empty : 504 [kg] (71.0 [%])
published operational weight empty : 452 [kg] (63.7 [%])
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weight crew : 81 [kg]
weight fuel for 1.5 hours flying : 52 [kg]
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operational weight : 637 [kg](89.8 [%])
estimated bomb load : 25 [kg]
operational weight bombing mission : 662 [kg]
fuel reserve : 27 [kg] enough for 0.77 [hours] flying
possible additional useful load : 21 [kg]
operational weight fully loaded : 710 [kg] with fuel tank filled for 100 [%]
published maximum take-off weight : 710 [kg] (100.0 [%])
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calculation : * 4 * (engine power)
power loading (operational without bombload) : 5.42 [kg/kW]
total power : 117.7 [kW] at 1200 [r.p.m]
calculation : *5* (loads)
manoeuvre load : 2.6 [g] at 1000 [m]
limit load : 4.5 [g] ultimate load : 6.8 [g] load factor : 1.3 [g]
design flight time : 1.60 [hours]
design cycles : 112 sorties, design hours : 180 [hours]
operational wing loading : 313 [N/m^2]
wing stress (3 g) during operation : 254 [N/kg] at 3g emergency manoeuvre
Fokker E.IV on the left, then a row of 5 Fokker D.III, and to the right 2 Fokker D.II and one Halberstadt D.II behind. Schau of Kesta 4 at Freiburg. (courtesy Berto Rutkowski)
calculation : *6* (angles of attack)
angle of attack zero lift : -1.16 ["]
max. angle of attack (stalling angle) : 12.15 ["]
angle of attack at max. speed : 1.87 ["]
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 : 0.26 [ ]
induced drag coefficient at max. speed : 0.0047 [ ]
drag coefficient at max. speed : 0.0687 [ ]
drag coefficient (zero lift) : 0.0640 [ ]
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) : 94 [km/hr] at 2350 [m](power :35 [%])
min. power speed (max range) : 108 [km/hr] at 2350 [m] (power:39 [%])
max. rate of climb speed : 95.2 [km/hr] at sea-level
cruising speed : 144 [km/hr] op 2350 [m] (power:63 [%])
design speed prop : 155 [km/hr]
maximum speed : 160 [km/hr] op 100 [m] (power:99 [%])
climbing speed at sea-level (without bombload) : 388 [m/min]
calculation : *9* (regarding various performances)
take-off distance at sea-level : 142 [m]
lift/drag ratio : 7.52 [ ]
max. practical ceiling : 5150 [m] with flying weight :573 [kg]
practical ceiling (operational weight) : 4725 [m] with flying weight :637 [kg] line 3385
practical ceiling fully loaded (mtow- 1 hour fuel) : 4475 [m] with flying weight :675 [kg]
published ceiling (4700 [m]
climb to 1500m (without bombload) : 4.37 [min]
climb to 3000m (without bombload) : 11.15 [min]
max. dive speed : 329.0 [km/hr] at 3475 [m] height
load factor at max. angle turn 2.34 ["g"]
turn radius at 500m: 53 [m]
time needed for 360* turn 10.0 [seconds] at 500m
calculation *10* (action radius & endurance)
operational endurance : 2.27 [hours] with 1 crew and 46 [kg] useful (bomb)load and 100.0 [%] fuel
published endurance : 2.00 [hours] with 1 crew and possible useful (bomb) load : 55 [kg] and 88.1 [%] fuel
action radius : 217 [km] with 1 crew and 20[kg] photo camera or bombload
max range theoretically with additional fuel tanks for total 210 [litre] fuel : 639 [km]
useful load with action-radius 250km : 33 [kg]
production : 4.82 [tonkm/hour]
oil and fuel consumption per tonkm : 9.41 [kg]
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Literature :
Fokkers uit de eerste wereldoorlog page 35
warplanes WWI page 56,87
Jane’s fighting aircraft WWI page 148f
German aircraft of the first world war page 91,92
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 25 April 2020 contact : info.aircraftinvestigation@gmail.com python 3.7.4