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weight and performance calculations for the Farman F.40
Farman F.40
role : two-seat armed reconnaissance and artillery observation
importance : ***
first flight : operational : January 1916
country : France
design : Henri & Maurice Farman
production : unknown (200+)
general information :
The F.40 combined best features of the aircraft designed previously by Henri and Maurice Farman. However, when it arrived at the front spring 1916 it was already obsolete. Still 47 France squadrons received the type and used it for reconnaissance and as light bomber during 1916. In 1917 it could not be used any more by day and it was operated solely as night bomber into 1918. It was nicknamed as “Horace Farman” > Henri + Maurice = Horace. In an effort to over-come the poor performance problems the F-40 was re-engined with a 160 hp Renault engine. Unfortunately, only a minimal addition of the types performance was achieved. The F-40bis were operated by the French, Belgium and British (RNAS). Some French records list the F-40bis as a Type 56.
Gap : 2.00m
users : France, Belgium, RNAS
crew : 2
armament : 1 movable 7.70 [mm] (0.303 in) Lewis machine-gun for the observer
engine : 1 Renault 8 G liquid-cooled 8 -cylinder V-engine 140 [hp](103.0 KW)
dimensions :
wingspan : 17.62 [m], length : 9.24 [m], height : 3.89[m]
wing area : 52.0 [m^2]
weights :
max.take-off weight : 1120 [kg]
empty weight operational : 748 [kg] bombload : 50 [kg]
performance :
maximum speed : 120 [km/u] op 2000 [m]
service ceiling : 4900 [m]
endurance : 2.33 [hours]
estimated action radius : 126 [km]
description :
2-bay biplane with fixed underwing 4 -wheel landing gear and tail strut
upper wingtips supported by slanted flying wires
two spar upper and lower wing
tail supported by two open tail booms
engine, fuel and bombload in or attached to fuselage, landing gear attached to the wing
airscrew :
fixed pitch 2 -bladed pusher airscrew with max. efficiency :0.63 [ ]
estimated diameter airscrew 2.95 [m]
angle of attack prop : 10.86 [ ]
fine pitch
reduction : 1.00 [ ]
airscrew revs : 1500 [r.p.m.]
pitch at Max speed 1.33 [m]
blade-tip speed at Vmax and max revs. : 234 [m/s]
calculation : *1* (dimensions)
mean wing chord : 1.69 [m]
calculated wing chord (rounded tips): 1.83 [m]
wing aspect ratio : 10.45 []
gap : 2.00 [m]
gap/chord : 1.19 [ ]
seize (span*length*height) : 633 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 2.2 [kg/hr]
fuel consumption(cruise speed) : 23.9 [kg/hr] (32.6 [litre/hr]) at 59 [%] power
distance flown for 1 kg fuel : 4.52 [km/kg]
estimated total fuel capacity : 86 [litre] (63 [kg])
Belgian F.40
calculation : *3* (weight)
weight engine(s) dry : 170.0 [kg] = 1.65 [kg/KW]
weight 9 litre oil tank : 1.2 [kg]
oil tank filled with 0.8 litre oil : 0.7 [kg]
oil in engine 6 litre oil : 5.1 [kg]
fuel in engine 1 litre fuel : 0.5 [kg]
weight 14 litre gravity patrol tank(s) : 1.4 [kg]
weight radiator : 14.8 [kg]
weight exhaust pipes & fuel lines 12.4 [kg]
weight cowling 4.1 [kg]
weight airscrew(s) (wood) incl. boss & bolts : 19.0 [kg]
total weight propulsion system : 228 [kg](20.4 [%])
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weight tail boom : 39 [kg]
fuselage skeleton (wood gauge : 7.02 [cm]): 117 [kg]
bracing : 8.0 [kg]
fuselage covering ( 10.5 [m2] doped linen fabric) : 3.4 [kg]
weight controls + indicators: 7.3 [kg]
weight seats : 6.0 [kg]
weight other details, lighting set, etc. : 5.1 [kg]
weight bomb storage : 3.5 [kg]
weight 72 [litre] main fuel tank empty : 6.9 [kg]
weight engine mounts & firewalls : 5 [kg]
total weight fuselage : 162 [kg](14.5 [%])
***************************************************************
weight wing covering (doped linen fabric) : 33 [kg]
F.40 with Medusa head painted on it
total weight ribs (54 ribs) : 67 [kg]
load on front upper spar (clmax) per running metre : 557.3 [N]
load on rear upper spar (vmax) per running metre : 161.8 [N]
total weight 8 spars : 79 [kg]
weight wings : 179 [kg]
weight wing/square meter : 3.45 [kg]
weight 8 interplane struts & cabane : 39.3 [kg]
weight cables (76 [m]) : 10.9 [kg] (= 144 [gram] per metre)
diameter cable : 4.8 [mm]
weight fin & rudder (3.6 [m2]) : 13.0 [kg]
weight stabilizer & elevator (5.0 [m2]): 17.5 [kg]
total weight wing surfaces & bracing : 260 [kg] (23.2 [%])
*******************************************************************
weight machine-gun(s) : 12.7 [kg]
weight pivot mounting mg :6.0 [kg]
weight armament : 19 [kg]
********************************************************************
wheel pressure : 280.0 [kg]
weight 4 wheels (670 [mm] by 79 [mm]) : 24.5 [kg]
weight tailskid : 3.1 [kg]
weight undercarriage with axle 34.8 [kg]
total weight landing gear : 62.3 [kg] (5.6 [%]
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calculated empty weight : 731 [kg](65.3 [%])
weight oil for 2.8 hours flying : 6.0 [kg]
weight cooling fluids : 21.2 [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 : 767 [kg] (68.5 [%])
published operational weight empty : 748 [kg] (66.8 [%])
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weight crew : 162 [kg]
weight fuel for 2.0 hours flying : 48 [kg]
********************************************************************
operational weight : 977 [kg](87.2 [%])
bomb load : 50 [kg]
operational weight bombing mission : 1027 [kg]
weight camera : 20 [kg]
operational weight photo mission : 997 [kg]
fuel reserve : 15 [kg] enough for 0.64 [hours] flying
possible additional useful load : 108 [kg]
operational weight fully loaded : 1120 [kg] with fuel tank filled for 100 [%]
published maximum take-off weight : 1120 [kg] (100.0 [%])
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calculation : * 4 * (engine power)
power loading (operational without bombload) : 9.49 [kg/kW]
total power : 103.0 [kW] at 1500 [r.p.m]
calculation : *5* (loads)
manoeuvre load : 2.3 [g] at 1000 [m]
limit load : 3.75 [g] ultimate load : 5.6 [g] load factor : 2.6 [g]
design flight time : 1.86 [hours]
design cycles : 590 sorties, design hours : 1100 [hours]
operational wing loading : 188 [N/m^2]
wing stress (3 g) during operation : 164 [N/kg] at 3g emergency manoeuvre
calculation : *6* (angles of attack)
angle of attack zero lift : -1.10 ["]
max. angle of attack (stalling angle) : 11.20 ["]
angle of attack at max. speed : 2.53 ["]
calculation : *7* (lift & drag ratios
lift coefficient at angle of attack 0° :0.10 [ ]
lift coefficient at max. angle of attack : 1.11 [ ]
lift coefficient at max. speed : 0.33 [ ]
induced drag coefficient at max. speed : 0.0044 [ ]
drag coefficient at max. speed : 0.0480 [ ]
drag coefficient (zero lift) : 0.0436 [ ]
calculation : *8* (speeds
stalling speed at sea-level (OW): 59 [km/u]
landing speed at sea-level (OW without bombload): 71 [km/hr]
min. drag speed (max endurance) = minimum speed*1.1 at cruise height : 73 [km/hr] at 2450 [m] (power:29 [%])
min. power speed (max range) : 82 [km/hr] at 2450 [m] (power:33 [%])
max. rate of climb speed : 73.5 [km/hr] at sea-level
cruising speed : 108 [km/hr] op 2450 [m] (power:53 [%])
design speed prop : 114 [km/hr]
maximum speed : 120 [km/hr] op 2000 [m] (power:72 [%])
climbing speed at sea-level (without bombload) : 246 [m/min]
calculation : *9* (regarding various performances)
take-off distance at sea-level : 69 [m]
lift/drag ratio : 11.88 [ ]
max. practical ceiling : 5400 [m] with flying weight :851 [kg]
practical ceiling (operational weight): 4900 [m] with flying weight :977 [kg]
practical ceiling fully loaded (mtow- 1 hour fuel) : 4425 [m] with flying weight :1096 [kg]
published ceiling (4900 [m]
climb to 1500m (without bombload) : 6.82 [min]
climb to 3000m (without bombload) : 16.91 [min]
max. dive speed : 289.8 [km/hr] at 3425 [m] height
load factor at max. angle turn 2.61 ["g"]
turn radius at 500m: 32 [m]
time needed for 360* turn 7.3 [seconds] at 500m
calculation *10* (action radius & endurance)
operational endurance : 2.64 [hours] with 2 crew and 128 [kg] useful (bomb)load and 100.0 [%] fuel
published endurance : 2.33 [hours] with 2 crew and possible useful (bomb) load : 135 [kg] and 88.1 [%] fuel
action radius : 386 [km] with 2 crew and 20[kg] photo camera/radio transmitter or bombload
max range theoretically with additional fuel tanks for total 400 [litre] fuel : 1326 [km]
useful load with action-radius 250km : 183 [kg]
production : 19.74 [tonkm/hour]
oil and fuel consumption per tonkm : 1.32 [kg]
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Literature :
Praktisch handboek vliegtuigen deel 1
https://en.wikipedia.org/wiki/Farman_F.40
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 23 January 2020 contact : info.aircraftinvestigation@gmail.com python 3.7.4