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weight and performance calculations for the Voisin-Farman Ibis
On Saturday 30 May 1908 Henry Farman made the first passenger flight in Europa with Ernest Archdeacon sitting beside him. At Ghent in Belgium they flew 1.24 km. Flying weight with two people was about 544 kg, calculated stalling speed will have been about 49 km/u, max. speed about 51 km/u, flying margins were very small and loaded like this the airplane could just keep airborne. Climbing speed 8m/min, max ceiling 88m > but because of flying so close to the stalling speed Henry Farman kept close to the ground at 7 [m] height for safety reason and for using the ground effect. Loaded like this it could only fly in a straight line. Calculated take-off distance 178 [m]. Just before take-off Henri Farman removed the radiator to save weight.
Voisin-Farman Ibis
role : experimental/research/flying trials
importance : ****
first flight : 14 March 1908 operational : March 1908
country : France
design : Voisin brothers
production : 1 prototype
general information :
With a part of the Deutsch-Archdeacon price money Henry Farman renewed the fabric covering and installed a 50hp Renault engine. On 14 March 1908 it made the first flight, it was indicated as Voisin-Farman Ibis. The Renault engine was no success and the Antoinette engine was re-installed. On March 21, 1908 Henry Farman flew a distance of 2 km. with it at Issy-les-Moulineaux. The Ibis flew 42 km in a closed circuit on 29 September 1908. In October 1908 Farman fitted ailerons on the upper and lower wing, the first practical use of ailerons. The official record for height was set at 25 [m] at 13 October 1908. On 30 October 1908 Henry Farman made the first over land flight, he flew the 1bis from Bouy to Reims, a distance of 27km. Then Farman converted the 1bis to a tri-plane by adding a wing on top, but this was no success and Farman soled the aircraft a the start of 1909 to an Austrian.
users : Henry Farman
crew : 1
passengers : 1
engine : 1 Antoinette 50hp liquid-cooled 8 -cylinder V-engine 50 [hp](37.3 KW)
dimensions :
wingspan : 10.0 [m], length : 11.63 [m], height : 3.56[m]
wing area : 41.34 [m^2]
weights :
max.take-off weight : 544 [kg]
empty weight operational : 400 [kg] useful load : 40 [kg]
3-side view, Voisin-Farman Ibis, area main surfaces is 445 square feet = 41.3 m2, weight radiator & water : 80 pounds = 36.3 kg > weight radiator 28.2 kg + water 8.1 kg. Note the reduces span of the tailplanes, at first the span was 6 [m], but after the first flights the span was reduced to 2.10 [m] 7.5 ft propeller = 2.29m
Span 395 in = 10.03m, length : 458 in = 11.63m height : 140 in = 3.56m
Wheel : 26 in = 66 cm area elevator : 45 square ft = 4.18 m2, area vertical rudder : 16.5 square ft = 1.53 m2
Weights : main surfaces 180 lb = 81.6 kg, chassis : 250 lb = 113.4 kg, tail framing 40 lb = 18.1 kg, tail surfaces 55 lb = 24.9 kg, tail wheels 13 lb = 5.9 kg, vertical rudder 10 lb = 4.5 kg, elevator 32 lb = 14.5 kg, engine 320 lb = 145.2 kg, radiator&water 80 lb = 36.3 kg pilot 170 lb = 77.1 kg, a total 1150 lb = 522 kg
performance :
maximum speed :57 [km/u] op 25 [m]
cruise speed :51 [km/u] op 25 [m]
service ceiling : 80 [m]
range : 42 [km]
estimated endurance : 0.82 [hours]
description :
2-bay biplane with fixed landing gear with tail wheel(s)
two spar upper and lower wing
tail supported by two open tail booms
canard wing
engines, landing gear, fuel and bombs in or attached to the fuselage
airscrew :
fixed pitch 2 -bladed pusher airscrew with max. efficiency :0.60 [ ]
diameter airscrew 2.29 [m]
angle of attack prop : 9.04 [ ]
fine pitch
reduction : 1.00 [ ]
airscrew revs : 1100 [r.p.m.]
pitch at Max speed 0.86 [m]
blade-tip speed at Vmax and max revs. : 133 [m/s]
calculation : *1* (dimensions)
measured wing chord : 2.08[m]
mean wing chord : 2.07 [m]
wing aspect ratio : 4.84 []
estimated gap : 1.91 [m]
gap/chord : 0.92 [ ]
seize (span*length*height) : 414 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 0.9 [kg/hr]
fuel consumption(cruise speed) : 19.0 [kg/hr] (26.0 [litre/hr]) at 99 [%] power
Voisin-Farman Ibis, at display in the Musee de l’air in Paris, Le Bourget. Note the smaller tail surfaces. In this aircraft, there are no vertical surfaces beside the pilot, so this is a different aircraft then used in Ghent in May 1908 ?
distance flown for 1 kg fuel : 2.68 [km/kg] at 40 [m] cruise height, sfc : 514.0 [kg/kwh]
estimated total fuel capacity : 21.39 [litre] (15.68 [kg])
calculation : *3* (weight)
weight engine(s) dry : 95.0 [kg] = 2.55 [kg/KW]
weight 2.0 litre oil tank : 0.17 [kg]
oil tank filled with 0.3 litre oil : 0.3 [kg]
oil in engine 2.1 litre oil : 1.9 [kg]
fuel in engine 0.3 litre fuel : 0.19 [kg]
weight 11.0 litre gravity patrol tank(s) : 1.7 [kg]
weight radiator : 28.2 [kg]
weight exhaust pipes & fuel lines 4.2 [kg]
weight cowling 1.5 [kg]
weight airscrew(s) (wood) incl. boss & bolts : 7.1 [kg]
total weight propulsion system : 140 [kg](25.7 [%])
***************************************************************
weight tail boom : 21 [kg]
fuselage skeleton (wood gauge : 4.62 [cm]): 63 [kg]
bracing : 4.6 [kg]
fuselage covering ( 16.6 [m2] doped linen fabric) : 5.3 [kg]
weight instruments. : 1.1 [kg]
During the flight demonstrations in Ghent, May 1908, Henry Farman had to battle the strong winds, taking-off with 12 [m/s] winds was no sinecure with the fragile aircraft.
The Ibis made flights with ground speeds of 73, 58 and 63 [km/hr], true air speed will have been around 65 [km/hr]
weight controls : 5.4 [kg]
weight seats : 3.0 [kg]
weight 10 [litre] main fuel tank empty : 0.8 [kg]
weight engine mount : 1.9 [kg]
total weight fuselage : 86 [kg](15.7 [%])
***************************************************************
weight wing covering (doped linen fabric) : 37 [kg]
total weight ribs (22 ribs) : 32 [kg]
load on front upper spar (clmax) per running metre : 413.5 [N]
load on rear upper spar (vmax) per running metre : 121.4 [N]
total weight 8 spars : 22 [kg]
weight wings : 92 [kg]
weight wing/square meter : 2.21 [kg]
weight 8 interplane struts & cabane : 22.2 [kg]
weight cables (70 [m]) : 2.4 [kg] (= 34 [gram] per metre)
diameter cable : 2.4 [mm]
area of canard wing : 2.0 [m2
weight canard wing :4.5 [kg]
weight fin & rudder (1.2 [m2]) : 2.7 [kg]
weight stabilizer & elevator (4.0 [m2]): 9.1 [kg]
total weight wing surfaces & bracing : 133 [kg] (24.4 [%])
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wheel pressure : 272.0 [kg]
weight 2 wheels (660 [mm] by 78 [mm]) : 11.8 [kg]
weight tailwheel(s) : 5.9 [kg]
weight undercarriage with axle 20.7 [kg]
total weight landing gear : 38.4 [kg] (7.0 [%]
*******************************************************************
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calculated empty weight : 396 [kg](72.9 [%])
weight oil for 1.0 hours flying : 0.9 [kg]
weight cooling fluids : 8.1 [kg]
calculated operational weight empty : 405 [kg] (74.5 [%])
published operational weight empty : 400 [kg] (73.5 [%])
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weight crew : 81 [kg]
weight fuel for 0.4 hours flying : 8 [kg]
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operational weight : 494 [kg](90.8 [%])
fuel reserve : 8.1 [kg] enough for 0.42 [hours] flying
possible additional useful load : 42 [kg]
operational weight fully loaded : 544 [kg] with fuel tank filled for 100 [%]
published maximum take-off weight : 544 [kg] (100.0 [%])
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calculation : * 4 * (engine power)
power loading (Take-off) : 14.59 [kg/kW]
power loading (operational without useful load) : 13.25 [kg/kW]
total power : 37.3 [kW] at 1100 [r.p.m]
calculation : *5* (loads)
manoeuvre load : 0.8 [g] at 1000 [m]
limit load : 3.0 [g] ultimate load : 4.5 [g] load factor : 2.6 [g]
design flight time : 0.66 [hours]
design cycles : 51 sorties, design hours : 20 [hours]
operational wing loading : 117 [N/m^2]
wing stress (3 g) during operation : 159 [N/kg] at 3g emergency manoeuvre
calculation : *6* (angles of attack)
angle of attack zero lift : -1.36 ["]
max. angle of attack (stalling angle) : 13.46 ["]
angle of attack at max. speed : 9.19 ["]
calculation : *7* (lift & drag ratios
lift coefficient at angle of attack 0° :0.10 [ ]
lift coefficient at max. angle of attack : 1.09 [ ]
lift coefficient at max. speed : 0.77 [ ]
induced drag coefficient at max. speed : 0.0701 [ ]
drag coefficient at max. speed : 0.2262 [ ]
drag coefficient (zero lift) : 0.1562 [ ]
calculation : *8* (speeds
stalling speed at sea-level (OW): 48 [km/u]
landing speed at sea-level: 50 [km/hr]
min. drag speed (max endurance) = minimum speed*1.1 at cruise height : 53 [km/hr] at 40 [m] (power:88 [%])
min. power speed (max range) : 53 [km/hr] at 40 [m] (power:88 [%])
cruising speed : 51 [km/hr] op 40 [m] (power:84 [%])
design speed prop : 54 [km/hr]
maximum speed : 57 [km/hr] op 25 [m] (power:100 [%])
climbing speed at sea-level : 59 [m/min]
calculation : *9* (regarding various performances)
take-off speed : 52.6 [km/u]
static prop wash : 59 [km/u]
take-off distance at sea-level : 110 [m]
lift/drag ratio : 3.70 [ ]
time to 500m : 12.43 [min]
max attainable height is limited by amount of fuel carried
published ceiling (80 [m]
practical ceiling (operational weight) : 706 [m] with flying weight :493 [kg] line 3385
turning speed at CLmax : 51.9 [km/u] at 50 [m] height
turn radius at 50m: 34 [m]
time needed for 360* turn 15.0 [seconds] at 50m
load factor at max. angle turn 1.18 ["g"]
calculation *10* (action radius & endurance)
operational endurance : 0.82 [hours] with 1 crew and 41.9 [kg] useful load and 100.0 [%] fuel
published endurance : 0.82 [hours] with 1 crew and possible useful load : 41.9 [kg] and 100.0 [%] fuel
maximum action radius : 77 [km] with 1 crew and 0 [kg] useful load ( 78.6 [litre] additional fuel needed)
max range theoretically with additional fuel tanks for total 78.6 [litre] fuel : 154.3 [km]
useful load with action-radius 250km : 0 [kg]
production (500 km) : 0 [tonkm/hour]
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Literature :
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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(c) B van der Zalm 19 July 2020 contact : info.aircraftinvestigation@gmail.com python 3.7.4