RAF F.E.8

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weight and performance calculations for the RAF F.E.8

RAF F.E.8

role : fighter

importance : ***

first flight : October 1915 operational : August 1916

country : United-Kingdom

design : John Kenworthy

production : 300 aircraft (Darracq Motor Engineering Co.250, Vickers , Weybridge 50)

general information :

Without an useful interrupter gear Kenworthy chose the pusher-

layout to have a fighter with an machine gun in the nose, not hampered by the propeller. First flight was in October 1915 and production started early 1916 but problems with stability and the Gnome rotary engine resulted that it became operational only in the summer of 1916, reaching the front in august. By that time new and superior German fighters had showed up and making clear the F.E.8 was no match. In spite of this the F.E.8 remained in frontline service till mid 1917. On 9 march 1917 five Albatros D.IIIs from Richthofens Jasta 11 destroyed 4 F.E.8’s and damaged another four of a formation of 9 F.E.8s of no.40 squadron.

The only ace flying the F.E.8 was Edwin Benbow.

He F.E.8 was designed before the arrival of the Fokker E.I, and no reaction to it.

users : RFC (29 squadron, 40 squadron, 41 squadron)

crew : 1

armament : 1 fixed 7.70 [mm] (0.303 in) Lewis machine-gun

engine : 1 Gnome B2 Monosoupape air-cooled 9 -cylinder Monosoupape rotary engine 100 [hp](73.6 KW)

dimensions :

wingspan : 9.6 [m], length : 7.21 [m], height : 2.79[m]

wing area : 20.25 [m^2]

weights :

max.take-off weight : 611 [kg]

empty weight operational : 406 [kg] bombload : 0 [kg]

performance :

maximum speed : 151 [km/hr] at sea-level

climbing speed : 219 [m/min]

service ceiling : 4420 [m]

estimated endurance : 3.5 [hours]

estimated action radius : 238 [km]

description :

2-bay biplane with fixed landing gear and tail strut

two spar upper and lower wing

tail supported by two open tail booms

engines, landing gear, fuel and bombs in or attached to the fuselage

airscrew :

fixed pitch 4 -bladed pusher airscrew with max. efficiency :0.60 [ ]

estimated diameter airscrew 2.60 [m]

angle of attack prop : 19.50 [ ]

reduction : 1.00 [ ]

airscrew revs : 1160 [r.p.m.]

pitch at Max speed 2.17 [m]

blade-tip speed at Vmax and max revs. : 163 [m/s]

calculation : *1* (dimensions)

mean wing chord : 1.05 [m]

calculated wing chord (rounded tips): 1.17 [m]

wing aspect ratio : 9.10 []

estimated gap : 1.41 [m]

gap/chord : 1.34 [ ]

seize (span*length*height) : 193 [m^3]

calculation : *2* (fuel consumption)

oil consumption : 8.1 [kg/hr]

fuel consumption(cruise speed) : 20.7 [kg/hr] (28.2 [litre/hr]) at 64 [%] power

distance flown for 1 kg fuel : 6.57 [km/kg]

estimated total fuel capacity : 112 [litre] (82 [kg])

calculation : *3* (weight)

weight engine(s) dry : 137.0 [kg] = 1.86 [kg/KW]

weight 40 litre oil tank : 5.0 [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 12 litre gravity patrol tank(s) : 1.2 [kg]

weight cowling 2.9 [kg]

weight airscrew(s) (wood) incl. boss & bolts : 25.7 [kg]

total weight propulsion system : 168 [kg](27.5 [%])

***************************************************************

F.E.8 s/n 7616 flown by 2Lt. Stanley Wedgewood Taylor, from Durban, South Africa, flight commander of 41 sq. earned the Military Cross during his time with 41 squadron.

weight tail boom : 14 [kg]

fuselage skeleton (wood gauge : 4.69 [cm]): 41 [kg]

bracing : 2.2 [kg]

fuselage covering ( 6.4 [m2] doped linen fabric) : 2.0 [kg]

weight controls + indicators: 5.7 [kg]

weight seats : 3.0 [kg]

weight other details, lighting set, etc. : 5.1 [kg]

weight 100 [litre] main fuel tank empty : 9.6 [kg]

weight engine mounts & firewalls : 4 [kg]

total weight fuselage : 72 [kg](11.8 [%])

***************************************************************

weight wing covering (doped linen fabric) : 13 [kg]

total weight ribs (47 ribs) : 36 [kg]

load on front upper spar (clmax) per running metre : 524.3 [N]

load on rear upper spar (vmax) per running metre : 186.3 [N]

total weight 8 spars : 27 [kg]

weight wings : 76 [kg]

weight wing/square meter : 3.75 [kg]

weight 8 interplane struts & cabane : 9.9 [kg]

weight cables (57 [m]) : 2.4 [kg] (= 42 [gram] per metre)

diameter cable : 2.6 [mm]

weight fin & rudder (1.1 [m2]) : 4.2 [kg]

weight stabilizer & elevator (1.9 [m2]): 7.4 [kg]

total weight wing surfaces & bracing : 100 [kg] (16.3 [%])

*******************************************************************

weight machine-gun(s) : 12.7 [kg]

weight fixed machine gun mounting : 1.1 [kg]

weight armament : 14 [kg]

********************************************************************

wheel pressure : 305.5 [kg]

weight 2 wheels (720 [mm] by 80 [mm]) : 13.7 [kg]

weight tailskid : 1.4 [kg]

weight undercarriage with axle 14.3 [kg]

total weight landing gear : 29.3 [kg] (4.8 [%]

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********************************************************************

calculated empty weight : 383 [kg](62.7 [%])

weight oil for 4.2 hours flying : 34.0 [kg]

weight 5 drums empty : 1.0 [kg]

weight ammunition (235 rounds) : 7.5 [kg]

weight automatic pistol with spare magazines : 1.2 [kg]

*******************************************************************

calculated operational weight empty : 426 [kg] (69.7 [%])

published operational weight empty : 406 [kg] (66.4 [%])

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| | o | |

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weight crew : 81 [kg]

weight fuel for 1.5 hours flying : 31 [kg]

********************************************************************

operational weight : 538 [kg](88.0 [%])

estimated bomb load : 25 [kg]

operational weight bombing mission : 563 [kg]

fuel reserve : 48 [kg] enough for 2.33 [hours] flying

operational weight fully loaded : 611 [kg] with fuel tank filled for 96 [%]

published maximum take-off weight : 611 [kg] (100.0 [%])

=||I>|

calculation : * 4 * (engine power)

power loading (operational without bombload) : 7.31 [kg/kW]

total power : 73.6 [kW] at 1160 [r.p.m]

calculation : *5* (loads)

manoeuvre load : 2.7 [g] at 1000 [m]

limit load : 4.5 [g] ultimate load : 6.8 [g] load factor : 2.1 [g]

design flight time : 2.80 [hours]

design cycles : 223 sorties, design hours : 625 [hours]

operational wing loading : 260 [N/m^2]

wing stress (3 g) during operation : 208 [N/kg] at 3g emergency manoeuvre

calculation : *6* (angles of attack)

angle of attack zero lift : -1.36 ["]

max. angle of attack (stalling angle) : 11.54 ["]

angle of attack at max. speed : 1.41 ["]

calculation : *7* (lift & drag ratios

lift coefficient at angle of attack 0° :0.12 [ ]

lift coefficient at max. angle of attack : 1.14 [ ]

lift coefficient at max. speed : 0.24 [ ]

induced drag coefficient at max. speed : 0.0037 [ ]

drag coefficient at max. speed : 0.0478 [ ]

drag coefficient (zero lift) : 0.0441 [ ]

calculation : *8* (speeds

stalling speed at sea-level (OW): 70 [km/u]

landing speed at sea-level (OW without bombload): 84 [km/hr]

min. drag speed (max endurance) : 90 [km/hr] at 2210 [m](power :37 [%])

min. power speed (max range) : 102 [km/hr] at 2210 [m] (power:40 [%])

max. rate of climb speed : 90.8 [km/hr] at sea-level

cruising speed : 136 [km/hr] op 2210 [m] (power:65 [%])

design speed prop : 146 [km/hr]

maximum speed : 151 [km/hr] op 100 [m] (power:99 [%])

climbing speed at sea-level (without bombload) : 265 [m/min]

calculation : *9* (regarding various performances)

take-off distance at sea-level : 136 [m]

lift/drag ratio : 9.55 [ ]

max. practical ceiling : 4950 [m] with flying weight :508 [kg]

practical ceiling (operational weight) : 4675 [m] with flying weight :538 [kg] line 3385

practical ceiling fully loaded (mtow- 1 hour fuel) : 4200 [m] with flying weight :590 [kg]

published ceiling (4420 [m]

climb to 1500m (without bombload) : 6.37 [min]

climb to 3000m (without bombload) : 16.03 [min]

max. dive speed : 281.9 [km/hr] at 3200 [m] height

load factor at max. angle turn 2.22 ["g"]

turn radius at 500m: 45 [m]

time needed for 360* turn 9.5 [seconds] at 500m

calculation *10* (action radius & endurance)

operational endurance : 3.83 [hours] with 1 crew and 25 [kg] useful (bomb)load and 96.5 [%] fuel

published endurance : 3.50 [hours] with 1 crew and possible useful (bomb) load : 32 [kg] and 88.1 [%] fuel

action radius : 277 [km] with 1 crew and 20[kg] photo camera or bombload

max range theoretically with additional fuel tanks for total 154 [litre] fuel : 742 [km]

useful load with action-radius 250km : 37 [kg]

production : 5.01 [tonkm/hour]

oil and fuel consumption per tonkm : 5.75 [kg]

°_I>-/

Literature :

Praktisch handboek vliegtuigen deel 1 page 177

Fighters 1914/19 page 21,100

Warplanes WWI page 37,44,55

Jane´s fighting aircraft WWI page 37f

Airfields and Airmen : Ypres – Michael O’Conner

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

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