AIRCRAFT INVESTIGATION

weight and performance calculations for the Santos-Dumont Demoiselle 20

Santos-Dumont Demoiselle 20

role : micro light sport airplane

importance : ****

first flight : 6 March 1909 operational : April 1909

country : France

design : Santos-Dumont

production : 12 aircraft

general information :

The prototype of the Demoiselle was project No. 19 and made its first flight in November 1907. On 17 November 1907, the aircraft flew 200m at Issy-les-Moulineaux. After No. 19 was damaged in a landing accident Santos-Dumont built the No.19b with a 24hp

Antoinette engine. It was followed in 1909 by the No.20 with a 30 hp Dutheil-Chalmers engine driving a mahogany Chauviere air propeller. For lateral control it used wing warping through cables connected to a harness the pilot was wearing.

For stearing the pilot had to move his body from left to right. This steering was far from easy and the plane was only kept under control in absolutely windless weather. But Santos_Dumont achieved succesfull fights with it. In April 1909, Santos-Dumont made a trip of 2 km with the plane and in September, he stayed in the air for 16 minutes, flying approximately 18 km. ( average speed : 67.5 km/h). With it’s empty flying weight of only 140 kgs it was the first microlight airplane capable of sustainable flights. The small airplane became populair with early aviators, it was one of the first “sporting”airplanes whit which dairing pilots could learn to fly.

In November 1909, Alberto Santos-Dumont made is last flight, a few months later he had a severe illness which led to his suicide in 1932.

In the Santos-Dumont machine a 2 cylinder opposed Darracq motor of 30 horse-power was used. It is of the water-cooled type, the cooling radiator being a gridiron of very thin 1/8 inch copper tubing, and hung on the side of the plane on either side of the engine. The cylinders have a bore of about 4½ inches (114 [mm]), and a stroke of about 4¾ inches (121 [mm]). The propeller is 2-bladed, 6½ feet (1.98 [m]) across, and is run at 1499 revolutions per minute, at which speed it exerts a pull of 242 lbs (110 kg).

construction : bamboo and steel tubes

users : Santos-Dumont

crew : 1

engine : 1 Dutheil-Chalmers (Darracq) 30hp water-cooled horizontally opposed two-cylinder flat twin piston engine 30 [hp](22.4 KW)

dimensions :

wingspan : 5.49 [m], length : 6.1 [m], height : 2.4[m]

wing area : 10.68 [m^2].

weights :

max.take-off weight : 240 [kg]

empty weight operational : 140 [kg] useful load : 0 [kg]

performance :

maximum speed :90 [km/hr] at sea-level

cruise speed :81 [km/u] op 50 [m]

service ceiling : 650 [m]

estimated action radius : 25 [km]

estimated endurance : 0.62 [hours]

description :

parasol wing with fixed landing gear and tail strut

two spar wing

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

airscrew :

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

diameter airscrew 1.98 [m]

angle of attack prop : 12.11 [ ]

reduction : 1.00 [ ]

airscrew revs : 1499 [r.p.m.]

pitch at Max speed 1.00 [m]

blade-tip speed at Vmax and max revs. : 157 [m/s]

calculation : *1* (dimensions)

wing chord : 1.96 [m]

mean wing chord : 1.95 [m]

calculated wing chord (square tips): 2.25 [m]

wing aspect ratio : 2.82 []

seize (span*length*height) : 80 [m^3]

calculation : *2* (fuel consumption)

oil consumption : 0.6 [kg/hr]

fuel consumption(cruise speed) : 6.8 [kg/hr] (9.2 [litre/hr]) at 86 [%] power

distance flown for 1 kg fuel : 11.96 [km/kg] at 325 [m] cruise height, sfc : 353.0 [kg/kwh]

estimated total fuel capacity : 6.47 [litre] (4.74 [kg])

calculation : *3* (weight)

weight engine(s) dry : 50.0 [kg] = 2.24 [kg/KW]

weight 1.0 litre oil tank : 0.09 [kg]

oil tank filled with 0.2 litre oil : 0.2 [kg]

oil in engine 1.2 litre oil : 1.1 [kg]

fuel in engine 0.2 litre fuel : 0.11 [kg]

Length : 18 ft 13 in = 5.82 [m] without propellor

Chord : 6 ft 7 in = 2.01 [m]

weight 6.5 litre gravity patrol tank(s) : 1.0 [kg]

weight radiator : 3.2 [kg]

weight exhaust pipes & fuel lines 2.5 [kg]

weight cowling 0.9 [kg]

weight airscrew(s) (wood) incl. boss & bolts : 4.4 [kg]

total weight propulsion system : 63 [kg](26.4 [%])

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fuselage skeleton (wood gauge : 3.15 [cm]): 16 [kg]

bracing : 0.7 [kg]

weight instruments. : 1.1 [kg]

weight controls : 3.4 [kg]

weight seats : 3.0 [kg]

weight engine mount : 1.1 [kg]

total weight fuselage : 25 [kg](10.3 [%])

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weight wing covering (doped linen fabric) : 7 [kg]

total weight ribs (10 ribs) : 14 [kg]

load on front upper spar (clmax) per running metre : 321.9 [N]

load on rear upper spar (vmax) per running metre : 113.5 [N]

total weight 4 spars : 6 [kg]

weight wings : 27 [kg]

weight wing/square meter : 2.56 [kg]

weight cables (22 [m]) : 1.0 [kg] (= 46 [gram] per metre)

diameter cable : 2.8 [mm]

weight fin & rudder (0.3 [m2]) : 0.9 [kg]

weight stabilizer & elevator (1.2 [m2]): 3.2 [kg]

total weight wing surfaces & bracing : 32 [kg] (13.5 [%])

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good soft ground capabilities

wheel pressure : 120.0 [kg]

weight 2 wheels (600 [mm] by 71 [mm]) : 9.6 [kg]

weight tailskid : 0.6 [kg]

weight undercarriage with axle 5.9 [kg]

total weight landing gear : 16.0 [kg] (6.7 [%]

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Length : 20 ft = 6.10 [m]

Span : 18 ft = 5.49 [m]

Chord : 1.96 [m]

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

calculated empty weight : 137 [kg](56.9 [%])

weight oil for 0.7 hours flying : 0.4 [kg]

weight cooling fluids : 4.8 [kg]

calculated operational weight empty : 142 [kg] (59.1 [%])

published operational weight empty : 140 [kg] (58.3 [%])

***o***

"

weight crew : 81 [kg]

weight fuel for 0.4 hours flying : 3 [kg]

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operational weight : 226 [kg](94.0 [%])

fuel reserve : 2.0 [kg] enough for 0.30 [hours] flying

possible additional useful load : 12 [kg]

operational weight fully loaded : 240 [kg] with fuel tank filled for 100 [%]

published maximum take-off weight : 240 [kg] (100.0 [%])

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calculation : * 4 * (engine power)

power loading (Take-off) : 10.73 [kg/kW]

power loading (operational without useful load) : 10.08 [kg/kW]

total power : 22.4 [kW] at 1499 [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 : 2.1 [g]

design flight time : 0.49 [hours]

design cycles : 405 sorties, design hours : 60 [hours]

operational wing loading : 207 [N/m^2]

wing stress (3 g) during operation : 243 [N/kg] at 3g emergency manoeuvre

calculation : *6* (angles of attack)

angle of attack zero lift : -1.76 ["]

max. angle of attack (stalling angle) : 14.97 ["]

angle of attack at max. speed : 7.82 ["]

calculation : *7* (lift & drag ratios

lift coefficient at angle of attack 0° :0.10 [ ]

lift coefficient at max. angle of attack : 0.95 [ ]

lift coefficient at max. speed : 0.54 [ ]

induced drag coefficient at max. speed : 0.0444 [ ]

drag coefficient at max. speed : 0.1319 [ ]

drag coefficient (zero lift) : 0.0875 [ ]

calculation : *8* (speeds

stalling speed at sea-level (OW): 68 [km/u]

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

landing speed at sea-level: 80 [km/hr]

min. drag speed (max endurance) : 77 [km/hr] at 325 [m](power :81 [%])

min. power speed (max range) : 77 [km/hr] at 325 [m] (power:81 [%])

cruising speed : 81 [km/hr] op 325 [m] (power:85 [%])

design speed prop : 86 [km/hr]

maximum speed : 90 [km/hr] op 50 [m] (power:99 [%])

climbing speed at sea-level : 86 [m/min]

calculation : *9* (regarding various performances)

take-off speed : 73.6 [km/u]

emergency/TO power : 35 [hp] at 1744 [rpm]

static prop wash : 91 [km/u]

take-off distance at sea-level : 51 [m]

lift/drag ratio : 4.36 [ ]

time to 500m : 7.54 [min]

time to 1000m : 25.82 [min]

published ceiling (650 [m]

practical ceiling (operational weight) : 1398 [m] with flying weight :226 [kg] line 3385

practical ceiling fully loaded (mtow- 30 min.fuel) : 1073 [m] with flying weight :237 [kg]

max. dive speed : 182.2 [km/hr] at 73 [m] height

turning speed at CLmax : 75.3 [km/u] at 50 [m] height

turn radius at 50m: 64 [m]

time needed for 360* turn 19.1 [seconds] at 50m

load factor at max. angle turn 1.22 ["g"]

calculation *10* (action radius & endurance)

estimated endurance : 0.62 [hours] with 1 crew and possible useful load : 13.0 [kg] and 88.1 [%] fuel

maximum action radius : 103 [km] with 1 crew and 0 [kg] useful load ( 23.4 [litre] additional fuel needed)

max range theoretically with additional fuel tanks for total 23.4 [litre] fuel : 205.2 [km]

useful load with range 500km : 0 [kg]

production (500 km) : 0 [tonkm/hour]

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Literature :

Historische vliegtuigen page 52,158

Praktisch Handboek vliegtuigen deel 1 page 62,63

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

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

notes :

An empty weight of 110 kg is published (wikipedia), but this seems to low with the engine weighing already 50 kgs. Flying weight of 143 kgs is also published, this is probably the flying weight without pilot (and fuel)

Lenght : 20 ft= 6.10 m

Span : 18 ft = 5.49 m

Wing area : 115 sq.ft = 10.68 m2

Weight engine : 110 lbs = 50 [kg]

Total weight : 242 lbs = 110 [kg], maybe this weight is without the engine ?