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weight and performance calculations for the Sommer (Humber) Biplane

The Sommer biplane design was inspired by the Farman III biplane. It can be recognized by the bended supports of the canard- elevator and the different tailplane.

Sommer (Humber) Biplane

role : mail airplane

importance : ****

first flight : 04 January 1910 at Mouzon operational : February 1911

country : France

design : Roger Sommer

production : ca. 40 aircraft, Mouzon, Ardennes, license built in the UK by Humber

general information :

Roger Sommer designed a biplane inspired by the Farman III. It was a successful airplane, by the spring of 1910 Sommer already had orders for 60 aircraft. He established a flying school at Douzy using his aircraft. The aircraft was also built under license in the UK by Humber. These were of mixed steel and wood construction. Henri Pequet made the first official air mail flight on 18 February 1911. He flew some 6500 letters from Allahabad to Naini Junction across the Jumna river in India, the 10km trip took 13 minutes.

Clement van Maasdijk made successful demonstration flights near Heerenveen the Netherlands, on 31 July 1910 taking of from the Thialf sport fields, watched by 6000 spectators, making flights over Heerenveen during up to 27 minutes.

users : M. Viateaux, Henri Pequet, Charles Rolls , Clement van Maasdijk

crew : 1

passengers : 1

engine : 1 Gnome 7 Omega air-cooled 7 -cylinder atmospheric inlet-valve rotary engine 50 [hp](37.3 KW)

dimensions :

wingspan : 10.36 [m], length : 12.5 [m], height : 3.5[m]

wing area : 36.0 [m^2]

weights :

max.take-off weight : 550 [kg]

empty weight operational : 320 [kg] useful load : 100 [kg]

performance :

maximum speed :60 [km/hr] at sea-level

cruise speed :54 [km/u] op 100 [m]

service ceiling : 2000 [m]

estimated action radius : 100 [km]

estimated endurance : 3.70 [hours]

description :

3-bay biplane with fixed underwing 4 -wheel landing gear and tail strut

two spar upper and lower wing

tail supported by two open tail booms

canard wing

engine, landing gear and useful-load in or attached to fuselage, fuel in gravity tank

airscrew :

fixed pitch 2 -bladed pusher airscrew with max. efficiency :0.61 [ ]

estimated diameter airscrew 2.50 [m]

angle of attack prop : 8.05 [ ]

fine pitch

reduction : 1.00 [ ]

airscrew revs : 1200 [r.p.m.]

pitch at Max speed 0.83 [m]

blade-tip speed at Vmax and max revs. : 158 [m/s]

calculation : *1* (dimensions)

wing chord : 1.83 [m]

mean wing chord : 1.74 [m]

calculated wing chord (square tips): 1.78 [m]

wing aspect ratio : 5.96 []

estimated gap : 1.93 [m]

gap/chord : 1.11 [ ]

seize (span*length*height) : 453 [m^3]

calculation : *2* (fuel consumption)

oil consumption : 3.4 [kg/hr]

fuel consumption(cruise speed) : 14.3 [kg/hr] (19.6 [litre/hr]) at 76 [%] power

distance flown for 1 kg fuel : 3.77 [km/kg] at 1000 [m] cruise height, sfc : 503.0 [kg/kwh]

estimated total fuel capacity : 82.20 [litre] (60.25 [kg])

calculation : *3* (weight)

weight engine(s) dry : 75.0 [kg] = 2.01 [kg/KW]

weight 17.5 litre oil tank : 1.49 [kg]

oil tank filled with 0.3 litre oil : 0.3 [kg]

oil in engine 0.2 litre oil : 0.2 [kg]

fuel in engine 0.3 litre fuel : 0.19 [kg]

weight 82.2 litre gravity patrol tank(s) : 12.3 [kg]

weight cowling 1.5 [kg]

weight airscrew(s) (wood) incl. boss & bolts : 9.7 [kg]

total weight propulsion system : 99 [kg](18.0 [%])

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weight tail boom : 14 [kg]

fuselage skeleton (wood gauge : 3.64 [cm]): 42 [kg]

bracing : 3.3 [kg]

weight instruments. : 1.1 [kg]

weight controls : 5.7 [kg]

weight seats : 3.0 [kg]

weight engine mount : 1.9 [kg]

total weight fuselage : 57 [kg](10.4 [%])

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weight wing covering (doped linen fabric) : 29 [kg]

total weight ribs (26 ribs) : 33 [kg]

load on front upper spar (clmax) per running metre : 277.5 [N]

load on rear upper spar (vmax) per running metre : 132.6 [N]

total weight 8 spars : 16 [kg]

weight wings : 78 [kg]

weight wing/square meter : 2.17 [kg]

weight 12 interplane struts & cabane : 22.6 [kg]

weight cables (90 [m]) : 2.3 [kg] (= 26 [gram] per metre)

diameter cable : 2.0 [mm]

area of canard wing : 1.7 [m2

weight canard wing :3.9 [kg]

weight fin & rudder (1.2 [m2]) : 2.9 [kg]

weight stabilizer & elevator (3.4 [m2]): 7.7 [kg]

total weight wing surfaces & bracing : 117 [kg] (21.4 [%])

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good soft ground capabilities

wheel pressure : 137.5 [kg]

weight 4 wheels (580 [mm] by 68 [mm]) : 22.5 [kg]

weight tailskid : 0.9 [kg]

weight undercarriage with axle 13.6 [kg]

total weight landing gear : 37.0 [kg] (6.7 [%]

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calculated empty weight : 311 [kg](56.5 [%])

weight oil for 4.4 hours flying : 14.9 [kg]

calculated operational weight empty : 326 [kg] (59.2 [%])

published operational weight empty : 320 [kg] (58.2 [%])

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weight crew : 81 [kg]

weight fuel for 1.0 hours flying : 14 [kg]

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operational weight : 421 [kg](76.6 [%])

fuel reserve : 45.9 [kg] enough for 3.20 [hours] flying

possible additional useful load : 83 [kg]

operational weight fully loaded : 550 [kg] with fuel tank filled for 100 [%]

published maximum take-off weight : 550 [kg] (100.0 [%])

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calculation : * 4 * (engine power)

power loading (Take-off) : 14.75 [kg/kW]

power loading (operational without useful load) : 11.29 [kg/kW]

total power : 37.3 [kW] at 1200 [r.p.m]

calculation : *5* (loads)

manoeuvre load : 1.0 [g] at 1000 [m]

limit load : 3.0 [g] ultimate load : 4.5 [g] load factor : 1.6 [g]

design flight time : 2.96 [hours]

design cycles : 90 sorties, design hours : 80 [hours]

operational wing loading : 115 [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 : -1.27 ["]

Clement van Maasdijk demonstrating at Heerenveen, 31 July 1910

max. angle of attack (stalling angle) : 13.05 ["]

angle of attack at max. speed : 7.36 ["]

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 : 0.68 [ ]

induced drag coefficient at max. speed : 0.0440 [ ]

drag coefficient at max. speed : 0.2221 [ ]

drag coefficient (zero lift) : 0.1781 [ ]

calculation : *8* (speeds

stalling speed at sea-level (OW): 46 [km/u]

stalling speed at sea-level (MTOW): 53 [km/u]

landing speed at sea-level: 54 [km/hr]

min. drag speed (max endurance) at cruise height : 54 [km/hr] at 1000 [m]

min. power speed (max range) : 54 [km/hr] at 1000 [m] (power:75 [%])

cruising speed : 54 [km/hr] op 1000 [m] (power:76 [%])

design speed prop : 57 [km/hr]

maximum speed : 60 [km/hr] op 100 [m] (power:98 [%])

climbing speed at sea-level : 116 [m/min]

calculation : *9* (regarding various performances)

take-off speed : 58.3 [km/u]

static prop wash : 67 [km/u]

take-off distance at sea-level : 105 [m]

lift/drag ratio : 3.85 [ ]

time to 500m : 5.09 [min]

time to 1000m : 13.25 [min]

time to 2000m : 95.03 [min]

published ceiling (2000 [m]

practical ceiling (operational weight) : 2063 [m] with flying weight :421 [kg] line 3385

practical ceiling fully loaded (mtow- 30 min.fuel) : 403 [m] with flying weight :543 [kg]

turning speed at CLmax : 54.4 [km/u] at 50 [m] height

turn radius at 50m: 25 [m]

time needed for 360* turn 10.3 [seconds] at 50m

load factor at max. angle turn 1.37 ["g"]

calculation *10* (action radius & endurance)

estimated endurance : 3.70 [hours] with 1 crew and possible useful load : 90.2 [kg] and 88.1 [%] fuel

maximum action radius : 270 [km] with 1 crew and 0 [kg] useful load ( 195.4 [litre] additional fuel needed)

max range theoretically with additional fuel tanks for total 195.4 [litre] fuel : 539.7 [km]

useful load with range 500km : 11 [kg]

production : 0.57 [tonkm/hour]

oil and fuel consumption per tonkm : 31.11 [kg]

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Fatal accidents

27 August 1910 Clement van Maasdijk , born in Den Haag, makes a test flight near to Schaarsbergen , North of Arnhem, at landgoed Warnsborn in preparation for a 4 days air show. Watched by his fiancée Jeanne Ladenius. After making a sharp turn he loses control and crashed from 50m high on the Warnbornse heide. (location 52°01’07”N, 5°52’05.8E)

Van Maasdijk is crushed and killed by the engine. The first fatality in Dutch aviation.

Van Maasdijk on the Warnbornse heide, shortly before his fatal crash. To the left his fiancée Jeanne Ladenius. The flying ground with hangar was situated at the Rustwatlaan.

Memorial stone at the crash site, the plain (heide) now called Heitje van Maasdijk

Literature :

Praktisch handboek vliegtuigen deel I page 65

Piston-engined airliners page 7

Vermetel vliegende Hollanders page 11

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/

content please mail to below mail address

Van Maasdijk in Den Haag, his flights from Hanenburg field 14 – 18 August 1910 were no success due to the strong winds it was to risky to fly. The woman to the left probably his fiancée Jeanne Ladenius.

(c) B van der Zalm 07 October 2020 contact : info.aircraftinvestigation@gmail.com python 3.7.4