Fokker E.II
role : fighter
first flight : operational : June 1915
country : Germany
design :
production : 49 aircraft
general information :
80 hp engine replaced by 100 hp U.I rotary engine and reduced span for more speed. It was built along with the E.I depending on the availability of the 80 hp or 100 hp engine.
On 13 June 1915, Anthony Fokker demonstrated the first E.II to an audience of German commanders, including Crown Prince Wilhelm of Germany, at a German Fifth Army airfield. On 23 and 24 June he demonstrated the aircraft at Douai to the German Sixth Army. It was during these demonstrations, only one week before any kills would be achieved in the Eindecker type, that Fokker himself attempted to engage an enemy aircraft but he was unable to find a target. The major difference between the types was a reduced wingspan on the E.II, intended to increase speed, but handling and climbing performance suffered. The type was therefore quickly superseded by the E.III. The E.II also had a larger fuel capacity of 90 litres (23.75 US gallons) to supply the Oberursel U.I's 54 litres/hour fuel consumption, as compared to the E.I's 69 litres (18.2 US gallons) capacity to feed its earlier U.0 rotary, which used 37 litres/hour of fuel.
users : Luftwaffe
crew : 1
armament : 1 synchronized 7.92 [mm] (0.312 in) Spandau LMG 08/15 machine-gun
engine : 1 Oberursel U.I air-cooled 9 -cylinder atmospheric inlet-valve rotary engine 100 [hp](73.6 KW)
dimensions :
wingspan : 8.0 [m], length : 7.1 [m], height : 2.6[m]
wing area : 16.0 [m^2]
weights :
max.take-off weight : 609 [kg]
empty weight operational : 380 [kg] bombload : 0 [kg]
performance :
maximum speed : 140 [km/hr] at sea-level
service ceiling : unknown
endurance : 1.87 [hours]
estimated action radius : 118 [km]
description :
shoulder-winged monoplane with fixed landing gear and tail strut
two spar 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 : 19.58 [ ]
reduction : 1.00 [ ]
airscrew revs : 1200 [r.p.m.]
pitch at Max speed 1.94 [m]
blade-tip speed at Vmax and max revs. : 151 [m/s]
calculation : *1* (dimensions)
mean wing chord : 2.00 [m]
calculated wing chord (rounded tips): 2.75 [m]
wing aspect ratio : 4.00 []
gap : 0.00 [m]
gap/chord : 0.00 [ ]
seize (span*length*height) : 148 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 6.3 [kg/hr]
fuel consumption(cruise speed) : 31.1 [kg/hr] (42.5 [litre/hr]) at 78 [%] power
distance flown for 1 kg fuel : 4.05 [km/kg]
estimated total fuel capacity : 90 [litre] (66 [kg])
calculation : *3* (weight)
weight engine(s) dry : 139.7 [kg] = 1.90 [kg/KW]
weight 17 litre oil tank : 1.5 [kg]
oil tank filled with 0.6 litre oil : 0.5 [kg]
oil in engine 0 litre oil : 0.4 [kg]
fuel in engine 1 litre fuel : 0.4 [kg]
weight 18 litre gravity patrol tank(s) : 2.7 [kg]
weight cowling 2.9 [kg]
weight airscrew(s) (wood) incl. boss & bolts : 16.9 [kg]
total weight propulsion system : 164 [kg](26.9 [%])
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fuselage skeleton (wood gauge : 5.24 [cm]): 50 [kg]
bracing : 2.5 [kg]
fuselage covering ( 9.5 [m2] doped linen fabric) : 3.0 [kg]
weight controls + indicators: 5.5 [kg]
weight seats : 3.0 [kg]
weight other details, lighting set, etc. : 5.1 [kg]
weight 72 [litre] main fuel tank empty : 5.8 [kg]
weight engine mounts & firewalls : 4 [kg]
total weight fuselage : 78 [kg](12.9 [%])
***************************************************************
weight wing covering (doped linen fabric) : 10 [kg]
total weight ribs (25 ribs) : 36 [kg]
load on front upper spar (clmax) per running metre : 628.7 [N]
load on rear upper spar (vmax) per running metre : 203.6 [N]
total weight 4 spars : 23 [kg]
weight wings : 69 [kg]
weight wing/square meter : 4.34 [kg]
weight cables (32 [m]) : 6.1 [kg] (= 192 [gram] per metre)
diameter cable : 5.6 [mm]
weight fin & rudder (0.7 [m2]) : 3.3 [kg]
weight stabilizer & elevator (1.8 [m2]): 7.9 [kg]
total weight wing surfaces & bracing : 87 [kg] (14.3 [%])
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weight machine-gun(s) : 17.0 [kg]
weight ammunition magazine(s) :2.3 [kg]
weight synchronizing system : 1.0 [kg]
weight armament : 20 [kg]
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wheel pressure : 304.5 [kg]
weight 2 wheels (660 [mm] by 79 [mm]) : 14.7 [kg]
weight tailskid : 1.6 [kg]
weight undercarriage with axle 13.8 [kg]
total weight landing gear : 30.1 [kg] (4.9 [%]
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calculated empty weight : 379 [kg](62.3 [%])
weight oil for 2.2 hours flying : 14.0 [kg]
weight ammunition (500 rounds) : 17.5 [kg]
*******************************************************************
calculated operational weight empty : 411 [kg] (67.5 [%])
published operational weight empty : 380 [kg] (62.4 [%])
---o---
"
weight crew : 81 [kg]
weight fuel for 1.5 hours flying : 47 [kg]
********************************************************************
operational weight : 538 [kg](88.4 [%])
estimated bomb load : 25 [kg]
operational weight bombing mission : 563 [kg]
fuel reserve : 19 [kg] enough for 0.62 [hours] flying
possible additional useful load : 26 [kg]
operational weight fully loaded : 609 [kg] with fuel tank filled for 100 [%]
published maximum take-off weight : 609 [kg] (100.0 [%])
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calculation : * 4 * (engine power)
power loading (operational without bombload) : 7.32 [kg/kW]
total power : 73.6 [kW] at 1200 [r.p.m]
calculation : *5* (loads)
manoeuvre load : 1.5 [g] at 1000 [m]
limit load : 4.5 [g] ultimate load : 6.8 [g] load factor : 2.3 [g]
design flight time : 1.50 [hours]
design cycles : 368 sorties, design hours : 550 [hours]
operational wing loading : 330 [N/m^2]
wing stress (3 g) during operation : 228 [N/kg] at 3g emergency manoeuvre
calculation : *6* (angles of attack)
angle of attack zero lift : -1.48 ["]
max. angle of attack (stalling angle) : 13.72 ["]
angle of attack at max.speed : 3.83 ["]
calculation : *7* (lift & drag ratios
lift coefficient at angle of attack 0° :0.10 [ ]
lift coefficient at max. angle of attack : 1.03 [ ]
lift coefficient at max. speed : 0.36 [ ]
induced drag coefficient at max. speed : 0.0137 [ ]
drag coefficient at max.speed : 0.0798 [ ]
drag coefficient (zero lift) : 0.0660 [ ]
calculation : *8* (speeds
stalling speed at sea-level (OW): 82 [km/u]
landing speed at sea-level (OW without bombload): 99 [km/hr]
min. drag speed (max endurance) : 99 [km/hr] at 1000 [m](power :57 [%])
min. power speed (max range) : 113 [km/hr] at 1000 [m] (power:64 [%])
max. rate of climb speed : 91.7 [km/hr] at sea-level
cruising speed : 126 [km/hr] op 1000 [m] (power:75 [%])
design speed prop : 136 [km/hr]
maximum speed : 140 [km/hr] op 100 [m] (power:99 [%])
climbing speed at sea-level (without bombload) : 214 [m/min]
calculation : *9* (regarding various performances)
take-off distance at sea-level : 286 [m]
lift/drag ratio : 5.97 [ ]
max. practical ceiling : 3400 [m] with flying weight :490 [kg]
practical ceiling (operational weight): 2850 [m] with flying weight :538 [kg]
practical ceiling fully loaded (mtow- 1 hour fuel) : 2425 [m] with flying weight :578 [kg]
published ceiling (0 [m]
climb to 1500m (without bombload) : 8.52 [min]
max. dive speed : 295.7 [km/hr] at 1425 [m] height
load factor at max. angle turn 1.53 ["g"]
turn radius at 500m: 74 [m]
time needed for 360* turn 16.0 [seconds] at 500m
calculation *10* (action radius & endurance)
operational endurance : 2.12 [hours] with 1 crew and 51 [kg] useful (bomb)load and 100.0 [%] fuel
published endurance : 1.87 [hours] with 1 crew and possible useful (bomb) load : 59 [kg] and 88.1 [%] fuel
action radius : 197 [km] with 1 crew and 20[kg] photo camera/radio transmitter or bombload
max range theoretically with additional fuel tanks for total 184 [litre] fuel : 545 [km]
useful load with action-radius 250km : 11 [kg]
production : 1.40 [tonkm/hour]
oil and fuel consumption per tonkm : 26.64 [kg]
I-°=/
°
Literature : They fought for the sky page 74
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 04 January 2019 contact : info.aircraftinvestigation@gmail.com python 3.7.4