Fokker D.VIIF
role : fighter
first flight : operational : August 1918
country : Germany
design : Reinhold Platz
production : 1000 aircraft
general information :
This version with BMW high/compression engine gave superb performance at height.
By mid-1918, some D.VIIs received the "over compressed" 138 kW (185 hp) BMW IIIa, the first product of the BMW firm. The BMW IIIa followed the SOHC, straight-six configuration of the Mercedes D.III but incorporated several improvements. Increased displacement, higher compression and an altitude-adjusting carburettor produced a marked increase in speed and climb rate at high altitude. Because the BMW IIIa was over compressed, using full throttle at altitudes below 2,000 m (6,600 ft) risked premature detonation in the cylinders and damage to the engine. At low altitudes, full throttle could produce up to 179 kW (240 hp) for a short time. Fokker-built aircraft with the new BMW engine were called D.VII(F), the suffix "F" standing for Max Friz, the engine designer.
BMW-powered aircraft entered service with Jasta 11 in late June 1918. Pilots clamoured for the D.VII(F), of which about 750 were built. Production of the BMW IIIa was limited and the D.VII continued to be produced with the 134 kW (180 hp) Mercedes D.IIIaü until the end of the war.
users : Luftwaffe
crew : 1
armament : 2 synchronized 7.92 [mm] (0.312 in) Spandau LMG 08/15 machine-guns
engine : 1 BMW IIIA liquid-cooled 6 -cylinder inline engine 200 [hp](147.1 KW)
dimensions :
wingspan : 8.92 [m], length : 7.0 [m], height : 2.75[m]
wing area : 20.5 [m^2]
weights :
max.take-off weight : 906 [kg]
empty weight operational : 698 [kg] bombload : 0 [kg]
performance :
maximum speed : 189 [km/u] op 1000 [m]
climbing speed : 312 [m/min]
service ceiling : 6980 [m]
endurance : 1.5 [hours]
estimated action radius : 128 [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 :0.64 [ ]
estimated diameter airscrew 2.86 [m]
angle of attack prop : 19.10 [ ]
reduction : 1.00 [ ]
airscrew revs : 1350 [r.p.m.]
pitch at Max speed 2.33 [m]
blade-tip speed at Vmax and max revs. : 209 [m/s]
calculation : *1* (dimensions)
mean wing chord : 1.15 [m]
calculated wing chord (rounded tips): 1.29 [m]
wing aspect ratio : 7.76 []
estimated gap : 1.33 [m]
gap/chord : 1.16 [ ]
seize (span*length*height) : 172 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 3.7 [kg/hr]
fuel consumption(cruise speed) : 39.8 [kg/hr] (54.3 [litre/hr]) at 78 [%] power
distance flown for 1 kg fuel : 4.27 [km/kg]
estimated total fuel capacity : 93 [litre] (68 [kg])
calculation : *3* (weight)
weight engine(s) dry : 293.0 [kg] = 1.99 [kg/KW]
weight 11 litre oil tank : 0.9 [kg]
oil tank filled with 1.1 litre oil : 1.0 [kg]
oil in engine 8 litre oil : 7.4 [kg]
fuel in engine 1 litre fuel : 0.7 [kg]
weight 23 litre gravity patrol tank(s) : 3.5 [kg]
weight radiator : 27.2 [kg]
weight exhaust pipes & fuel lines 13.0 [kg]
weight self-starter : 3.6 [kg]
weight cowling 5.9 [kg]
weight airscrew(s) (wood) incl. boss & bolts : 22.1 [kg]
total weight propulsion system : 377 [kg](41.6 [%])
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fuselage skeleton (wood gauge : 5.87 [cm]): 62 [kg]
bracing : 3.0 [kg]
fuselage covering ( 9.3 [m2] doped linen fabric) : 3.0 [kg]
weight controls + indicators: 5.6 [kg]
weight seats : 3.0 [kg]
weight other details, lighting set, etc. : 5.1 [kg]
weight 69 [litre] main fuel tank empty : 5.6 [kg]
weight engine mounts & firewalls : 7 [kg]
total weight fuselage : 94 [kg](10.4 [%])
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weight wing covering (doped linen fabric) : 13 [kg]
total weight ribs (64 ribs) : 54 [kg]
load on front upper spar (clmax) per running metre : 785.6 [N]
load on rear upper spar (vmax) per running metre : 301.9 [N]
total weight 8 spars : 36 [kg]
weight wings : 103 [kg]
weight wing/square meter : 5.01 [kg]
weight 4 interplane struts & cabane : 7.7 [kg]
weight cables (44 [m]) : 2.5 [kg] (= 56 [gram] per metre)
diameter cable : 3.0 [mm]
weight fin & rudder (0.9 [m2]) : 4.8 [kg]
weight stabilizer & elevator (2.3 [m2]): 11.7 [kg]
total weight wing surfaces & bracing : 129 [kg] (14.3 [%])
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Fokker D.VIIF in use by the Dutch LVA after WWI
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 : 453.0 [kg]
weight 2 wheels (770 [mm] by 97 [mm]) : 21.6 [kg]
weight tailskid : 2.0 [kg]
weight undercarriage with axle 18.6 [kg]
total weight landing gear : 42.3 [kg] (4.7 [%]
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calculated empty weight : 683 [kg](75.4 [%])
weight oil for 1.8 hours flying : 6.6 [kg]
weight cooling fluids : 31.8 [kg]
weight ammunition (1000 rounds) : 35.0 [kg]
weight signal pistol with cartridges : 3.6 [kg]
weight automatic pistol with spare magazines : 1.2 [kg]
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calculated operational weight empty : 761 [kg] (84.0 [%])
published operational weight empty : 698 [kg] (77.0 [%])
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weight crew : 81 [kg]
weight fuel for 1.5 hours flying : 60 [kg]
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Ernst Udet before D.VIIF 4253/18 jasta 4
operational weight : 902 [kg](99.5 [%])
bombload could not be carried with fuel for 2 hours flying time
fuel reserve : 4 [kg] enough for 0.11 [hours] flying
operational weight fully loaded : 906 [kg] with fuel tank filled for 95 [%]
published maximum take-off weight : 906 [kg] (100.0 [%])
D.VIIF flown by Ernst Udet
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calculation : * 4 * (engine power)
power loading (operational without bombload) : 6.13 [kg/kW]
total power : 147.1 [kW] at 1350 [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 : 2.0 [g]
design flight time : 1.20 [hours]
design cycles : 292 sorties, design hours : 350 [hours]
operational wing loading : 431 [N/m^2]
wing stress (3 g) during operation : 258 [N/kg] at 3g emergency manoeuvre
calculation : *6* (angles of attack)
angle of attack zero lift : -2.00 ["]
max. angle of attack (stalling angle) : 11.51 ["]
angle of attack at max. speed : 1.31 ["]
calculation : *7* (lift & drag ratios
lift coefficient at angle of attack 0° :0.17 [ ]
lift coefficient at max. angle of attack : 1.15 [ ]
lift coefficient at max. speed : 0.28 [ ]
induced drag coefficient at max. speed : 0.0058 [ ]
drag coefficient at max. speed : 0.0570 [ ]
drag coefficient (zero lift) : 0.0512 [ ]
calculation : *8* (speeds
stalling speed at sea-level (OW): 89 [km/u]
landing speed at sea-level (OW without bombload): 107 [km/hr]
min. drag speed (max endurance) : 124 [km/hr] at 3490 [m](power :44 [%])
min. power speed (max range) : 140 [km/hr] at 3490 [m] (power:49 [%])
max. rate of climb speed : 112.6 [km/hr] at sea-level
cruising speed : 170 [km/hr] op 3490 [m] (power:66 [%])
design speed prop : 183 [km/hr]
maximum speed : 189 [km/hr] op 1000 [m] (power:100 [%])
climbing speed at sea-level (without bombload) : 311 [m/min]
calculation : *9* (regarding various performances)
take-off distance at sea-level : 165 [m]
lift/drag ratio : 8.18 [ ]
max. practical ceiling : 7625 [m] with flying weight :822 [kg]
practical ceiling (operational weight): 7025 [m] with flying weight :902 [kg]
practical ceiling fully loaded (mtow- 1 hour fuel) : 7275 [m] with flying weight :866 [kg]
published ceiling (6980 [m]
climb to 1500m (without bombload) : 4.79 [min]
climb to 3000m (without bombload) : 9.58 [min]
max. dive speed : 460.1 [km/hr] at 6275 [m] height
load factor at max. angle turn 2.09 ["g"]
turn radius at 500m: 75 [m]
time needed for 360* turn 12.8 [seconds] at 500m
calculation *10* (action radius & endurance)
operational endurance : 1.11 [hours] with 1 crew and 20 [kg] useful load and 65.0 [%] fuel
published endurance : 1.50 [hours] with 1 crew and possible useful (bomb) load : 4 [kg] and 88.1 [%] fuel
action radius : 94 [km] with 1 crew and 20[kg] photo camera/radio transmitter or bombload
max range theoretically with additional fuel tanks for total 142 [litre] fuel : 444 [km]
useful load with action-radius 250km : 0 [kg]
production (500 km) : 0 [tonkm/hour]
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Literature :
Warplanes WW1 page 121,123f
Famous Aircraft of all time page 93
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 21 August 2019 contact : info.aircraftinvestigation@gmail.com python 3.7.4