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weight and performance calculations for the Voisin 5
Voisin 5 LAS
role : light ground attack aircraft and co-op
importance : ****
first flight : 1915 operational : November 1915
country : France
design :
production : 350 aircraft
general information :
Out of the Voisin III, the Voisin 5 was developed with a stronger 150 Salmson P9 engine. The airframe was strengthened and the central nacelle streamlined. The new engine was placed on a raised platform to provide clearance for the propeller and was angled to provide downward thrust. In addition, the landing gear was strengthened and the wing chord was increased from the roots to the wing tips. For ground attack it could be fitted with a heavy 37mm cannon. It was not so popular with its crew because the performance compared to the Voisin III had not improved much in terms of speed and payload, but it did well for ground attacks with the heavy cannon.The new aircraft was given the STAé designation Voisin Type V, while the factory designation was Voisin LAS. The S stood for surélevé (raised) which indicated the raised engine mount. The previous Type III variant had an exhaust system which permitted fumes to escape freely; the Type V incorporated a more effective system of twin exhaust pipes.
Crew member posing for a Voisin LAS Canon at Bruay-en-Artois airbase in May 1915
users : France
crew : 2
armament : 1 movable 37.00 [mm] (1.457 in) Hotchkiss canon
engine : 1 Salmson Canton-Unne 9P liquid-cooled 9 -cylinder radial engine 150 [hp](110.3 KW)
dimensions :
wingspan : 14.75 [m], length : 9.53 [m], height : 3.63[m]
wing area : 45.0 [m^2]
weights :
max.take-off weight : 1470 [kg]
empty weight operational (estimation): 1050.0 [kg] bombload : 60 [kg]
performance :
maximum speed : 112 [km/hr] at sea-level
service ceiling : 3500 [m]
endurance : 3.5 [hours]
estimated action radius : 176 [km]
description :
3-bay biplane with fixed landing gear with nosewheel 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 2 -bladed pusher airscrew with max. efficiency :0.63 [ ]
estimated diameter airscrew 2.66 [m]
angle of attack prop : 12.44 [ ]
fine pitch
reduction : 1.00 [ ]
airscrew revs : 1350 [r.p.m.]
pitch at Max speed 1.38 [m]
blade-tip speed at Vmax and max revs. : 191 [m/s]
calculation : *1* (dimensions)
mean wing chord : 1.53 [m]
calculated wing chord (rounded tips): 1.66 [m]
wing aspect ratio : 9.67 []
estimated gap : 1.28 [m]
gap/chord : 0.84 [ ]
seize (span*length*height) : 510 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 3.9 [kg/hr]
fuel consumption(cruise speed) : 30.4 [kg/hr] (41.5 [litre/hr]) at 70 [%] power
distance flown for 1 kg fuel : 3.31 [km/kg]
estimated total fuel capacity : 165 [litre] (121 [kg])
calculation : *3* (weight)
weight engine(s) dry : 292.4 [kg] = 2.65 [kg/KW]
weight 21 litre oil tank : 1.8 [kg]
oil tank filled with 0.8 litre oil : 0.7 [kg]
oil in engine 6 litre oil : 5.5 [kg]
fuel in engine 1 litre fuel : 0.6 [kg]
weight 18 litre gravity patrol tank(s) : 2.6 [kg]
weight radiator : 15.8 [kg]
weight exhaust pipes & fuel lines 13.8 [kg]
weight cowling 4.4 [kg]
weight airscrew(s) (wood) incl. boss & bolts : 19.0 [kg]
total weight propulsion system : 355 [kg](24.1 [%])
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weight tail boom : 50 [kg]
fuselage skeleton (wood gauge : 7.82 [cm]): 149 [kg]
bracing : 10.5 [kg]
fuselage covering ( 11.2 [m2] doped linen fabric) : 3.6 [kg]
weight controls + indicators: 7.0 [kg]
weight seats : 6.0 [kg]
weight other details, lighting set, etc. : 5.1 [kg]
weight bomb storage : 4.2 [kg]
weight 147 [litre] main fuel tank empty : 11.8 [kg]
weight engine mounts & firewalls : 6 [kg]
total weight fuselage : 203 [kg](13.8 [%])
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weight wing covering (doped linen fabric) : 29 [kg]
total weight ribs (79 ribs) : 87 [kg]
load on front upper spar (clmax) per running metre : 907.5 [N]
load on rear upper spar (vmax) per running metre : 279.1 [N]
total weight 8 spars : 107 [kg]
weight wings : 223 [kg]
weight wing/square meter : 4.96 [kg]
weight 12 interplane struts & cabane : 14.2 [kg]
weight cables (87 [m]) : 14.7 [kg] (= 168 [gram] per metre)
diameter cable : 5.2 [mm]
weight fin & rudder (2.5 [m2]) : 12.9 [kg]
weight stabilizer & elevator (4.3 [m2]): 21.7 [kg]
total weight wing surfaces & bracing : 286 [kg] (19.5 [%])
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weight machine-gun(s) : 85.0 [kg]
weight pivot mounting mg :6.0 [kg]
weight armament : 91 [kg]
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wheel pressure : 646.8 [kg]
weight 4 wheels (730 [mm] by 86 [mm]) : 39.8 [kg]
weight tailskid : 3.8 [kg]
weight undercarriage with axle 44.1 [kg]
total weight landing gear : 87.7 [kg] (6.0 [%]
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Ltt Louis Dubuis, commandant l’escadrille VC 111 posant devant un Voisin Canon type 5 (LAS) de son unité. Devant lui, sont exposés les trois types d’obus mis en œuvre par le canon de cet avion. Deux sont explosifs et un à grenailles (au milieu). L’avion porte le nom de baptême de "Sergent Foucher", pilote de l’escadrille V 24 tué dans un accident aérien, le 18.04.1915. Photo Colonel Louis Dubuis transmis par sa famille, via M. Laurent Kloepfer.
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calculated empty weight : 1023 [kg](69.6 [%])
weight oil for 4.2 hours flying : 16.2 [kg]
weight cooling fluids : 23.8 [kg]
weight 1 drums empty : 2.1 [kg]
weight ammunition (100 rounds) : 59.3 [kg]
weight automatic pistol with spare magazines : 1.2 [kg]
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calculated operational weight empty : 1123 [kg] (76.4 [%])
estimated operational weight empty : 1050 [kg] (71.4 [%])
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weight crew : 162 [kg]
weight fuel for 2.0 hours flying : 61 [kg]
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operational weight : 1346 [kg](91.6 [%])
bomb load : 60 [kg]
operational weight bombing mission : 1406 [kg]
fuel reserve : 60 [kg] enough for 1.97 [hours] flying
possible additional useful load : 4 [kg]
operational weight fully loaded : 1470 [kg] with fuel tank filled for 100 [%]
published maximum take-off weight : 1470 [kg] (100.0 [%])
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calculation : * 4 * (engine power)
power loading (operational without bombload) : 12.20 [kg/kW]
total power : 110.3 [kW] at 1350 [r.p.m]
calculation : *5* (loads)
manoeuvre load : 1.3 [g] at 1000 [m]
limit load : 3.25 [g] ultimate load : 4.9 [g] load factor : 2.4 [g]
design flight time : 2.80 [hours]
design cycles : 571 sorties, design hours : 1600 [hours]
operational wing loading : 293 [N/m^2]
wing stress (3 g) during operation : 178 [N/kg] at 3g emergency manoeuvre
calculation : *6* (angles of attack)
angle of attack zero lift : -1.12 ["]
max. angle of attack (stalling angle) : 11.53 ["]
angle of attack at max. speed : 4.47 ["]
calculation : *7* (lift & drag ratios
lift coefficient at angle of attack 0° :0.10 [ ]
lift coefficient at max. angle of attack : 1.13 [ ]
lift coefficient at max. speed : 0.50 [ ]
induced drag coefficient at max. speed : 0.0146 [ ]
drag coefficient at max. speed : 0.0830 [ ]
drag coefficient (zero lift) : 0.0684 [ ]
calculation : *8* (speeds
stalling speed at sea-level (OW): 74 [km/u]
landing speed at sea-level (OW without bombload): 89 [km/hr]
min. drag speed (max endurance) = minimum speed*1.1 at cruise height : 89 [km/hr] at 1750 [m] (power:62 [%])
min. power speed (max range) : 89 [km/hr] at 1750 [m] (power:62 [%])
cruising speed : 101 [km/hr] op 1750 [m] (power:73 [%])
design speed prop : 106 [km/hr]
maximum speed : 112 [km/hr] op 100 [m] (power:99 [%])
climbing speed at sea-level (without bombload) : 130 [m/min]
calculation : *9* (regarding various performances)
take-off distance at sea-level : 208 [m]
lift/drag ratio : 7.90 [ ]
max. practical ceiling : 3500 [m] with flying weight :1159 [kg]
practical ceiling (operational weight): 2550 [m] with flying weight :1346 [kg]
practical ceiling fully loaded (mtow- 1 hour fuel) : 2075 [m] with flying weight :1440 [kg]
published ceiling (3500 [m]
climb to 1500m (without bombload) : 13.96 [min]
max. dive speed : 280.9 [km/hr] at 1075 [m] height
load factor at max. angle turn 1.48 ["g"]
turn radius at 500m: 61 [m]
time needed for 360* turn 15.0 [seconds] at 500m
calculation *10* (action radius & endurance)
operational endurance : 3.97 [hours] with 2 crew and 64 [kg] useful (bomb)load and 100.0 [%] fuel
published endurance : 3.50 [hours] with 2 crew and possible useful (bomb) load : 78 [kg] and 88.1 [%] fuel
action radius : 273 [km] with 2 crew and 20[kg] photo camera/radio transmitter or bombload
max range theoretically with additional fuel tanks for total 445 [litre] fuel : 1081 [km]
useful load with action-radius 250km : 175 [kg]
production : 17.67 [tonkm/hour]
oil and fuel consumption per tonkm : 1.94 [kg]
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Literature :
Praktisch handboek vliegtuigen deel 1 page137
Bombers 1914-19 page 20
Oorlogsvliegtuigen 1914-1918 page 32
Tussen vleugels van linnen page 62,63
Bomber 1914-1939 page 7
Jane’s fighting aircraft WWI page 124
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 November 2019 contact : info.aircraftinvestigation@gmail.com python 3.7.4