Rumpler C.I
role : two-seat armed reconnaissance and artillery observation
first flight : operational : April 1915
country : Germany
design :
production : ca. 400 aircraft till June 1917
general information :
The Rumpler C.I was one on the first German armed 2-seaters of the C-class. A big advantage was that now the observer was in the back-seat with a more free field of fire for the Parabellum machine gun.
It was a fine airplane to fly and was used for long time at the front, even till February 1918 ! It was built by several factories under license and October 1916 about 250 C.I’s were serving at the front. It was used for many different tasks made possible by the good flying qualities.
Endurance 4 hr. on 240 litres fuel (200 main, 40 gravity)
users : Germany
crew : 2
armament : 1 movable 7.92 [mm] (0.312 in) Parabellum MG 14 machine-gun for the observer later production aircraft also carried a synchronized Spandau machine gun
engine : 1 Mercedes D.III liquid-cooled 6 -cylinder inline engine 163 [hp](119.9 KW)
This three-view drawing is taken from German Aircraft of the First World War (GAFWW) page 197 drawn by L. E. Bradford (see bibliography). Note the arrow shape wing !?
dimensions :
wingspan : 12.15 [m], length : 7.85 [m], height : 3.08[m]
wing area : 35.7 [m^2]
weights :
max.take-off weight : 1330 [kg]
empty weight operational (estimation): 900.0 [kg] bombload : 100 [kg]
performance :
maximum speed : 152 [km/hr] at sea-level
climbing speed : 120 [m/min]
service ceiling : 5030 [m]
endurance : 5.19 [hours]
estimated action radius : 355 [km]
description :
2-bay biplane with fixed landing gear and tail strut
two spar upper and lower wing
engines, landing gear, fuel and bombs in or attached to the fuselage
airscrew :
fixed pitch 2 -bladed tractor airscrew with max. efficiency :0.63 [ ]
estimated diameter airscrew 2.70 [m]
angle of attack prop : 15.88 [ ]
reduction : 1.00 [ ]
airscrew revs : 1400 [r.p.m.]
pitch at Max speed 1.81 [m]
blade-tip speed at Vmax and max revs. : 202 [m/s]
calculation : *1* (dimensions)
mean wing chord : 1.47 [m]
calculated wing chord (rounded tips): 1.62 [m]
wing aspect ratio : 8.27 []
estimated gap : 1.68 [m]
gap/chord : 1.14 [ ]
seize (span*length*height) : 294 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 2.5 [kg/hr]
fuel consumption(cruise speed) : 29.8 [kg/hr] (40.7 [litre/hr]) at 65 [%] power
distance flown for 1 kg fuel : 4.59 [km/kg]
estimated total fuel capacity : 240 [litre] (176 [kg])
calculation : *3* (weight)
weight engine(s) dry : 299.0 [kg] = 2.49 [kg/KW]
weight 20 litre oil tank : 1.7 [kg]
oil tank filled with 0.9 litre oil : 0.8 [kg]
oil in engine 7 litre oil : 6.0 [kg]
fuel in engine 1 litre fuel : 0.6 [kg]
weight 17 litre gravity patrol tank(s) : 2.6 [kg]
weight radiator : 17.2 [kg]
weight exhaust pipes & fuel lines 11.6 [kg]
weight cowling 4.8 [kg]
weight airscrew(s) (wood) incl. boss & bolts : 19.0 [kg]
total weight propulsion system : 362 [kg](27.2 [%])
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fuselage skeleton (wood gauge : 7.60 [cm]): 116 [kg]
bracing : 6.4 [kg]
fuselage covering ( 11.6 [m2] doped linen fabric) : 3.7 [kg]
weight controls + indicators: 6.2 [kg]
weight seats : 6.0 [kg]
weight other details, lighting set, etc. : 5.1 [kg]
weight bomb storage : 7.0 [kg]
weight 222 [litre] main fuel tank empty : 17.8 [kg]
weight oxygen/compressed air flasks for high altitude : 11.3 [kg]
weight engine mounts & firewalls : 6 [kg]
total weight fuselage : 186 [kg](14.0 [%])
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weight wing covering (doped linen fabric) : 23 [kg]
total weight ribs (74 ribs) : 79 [kg]
load on front upper spar (clmax) per running metre : 929.9 [N]
load on rear upper spar (vmax) per running metre : 312.1 [N]
total weight 8 spars : 79 [kg]
weight wings : 181 [kg]
weight wing/square meter : 5.06 [kg]
weight 8 interplane struts & cabane : 25.0 [kg]
weight cables (72 [m]) : 8.9 [kg] (= 124 [gram] per metre)
diameter cable : 4.5 [mm]
weight fin & rudder (1.7 [m2]) : 8.9 [kg]
weight stabilizer & elevator (4.0 [m2]): 20.6 [kg]
total weight wing surfaces & bracing : 244 [kg] (18.3 [%])
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weight machine-gun(s) : 9.5 [kg]
weight pivot mounting mg :5.0 [kg]
weight armament : 14 [kg]
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wheel pressure : 665.0 [kg]
weight 2 wheels (840 [mm] by 129 [mm]) : 41.0 [kg]
weight tailskid : 3.4 [kg]
weight undercarriage with axle 18.9 [kg]
total weight landing gear : 63.4 [kg] (4.8 [%]
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calculated empty weight : 869 [kg](65.3 [%])
weight oil for 6.2 hours flying : 15.7 [kg]
weight cooling fluids : 25.9 [kg]
weight 1 drums empty : 2.3 [kg]
weight ammunition (500 rounds) : 19.8 [kg]
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calculated operational weight empty : 930 [kg] (70.0 [%])
estimated operational weight empty : 900 [kg] (67.7 [%])
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weight crew : 162 [kg]
weight (electrical heated) clothing for high altitude : 12.0 [kg]
weight fuel for 2.0 hours flying : 60 [kg]
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operational weight : 1164 [kg](87.5 [%])
bomb load : 100 [kg]
operational weight bombing mission : 1264 [kg]
weight camera : 20 [kg]
operational weight photo mission : 1184 [kg]
fuel reserve : 116 [kg] enough for 3.89 [hours] flying
possible additional useful load : 30 [kg]
operational weight fully loaded : 1330 [kg] with fuel tank filled for 100 [%]
published maximum take-off weight : 1330 [kg] (100.0 [%])
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calculation : * 4 * (engine power)
power loading (operational without bombload) : 9.71 [kg/kW]
total power : 119.9 [kW] at 1400 [r.p.m]
calculation : *5* (loads)
manoeuvre load : 2.2 [g] at 1000 [m]
limit load : 3.75 [g] ultimate load : 5.6 [g] load factor : 2.2 [g]
design flight time : 3.63 [hours]
design cycles : 317 sorties, design hours : 1150 [hours]
operational wing loading : 325 [N/m^2]
wing stress (3 g) during operation : 193 [N/kg] at 3g emergency manoeuvre
calculation : *6* (angles of attack)
angle of attack zero lift : -1.16 ["]
max.angle of attack (stalling angle) : 12.12 ["]
angle of attack at max.speed : 2.27 ["]
calculation : *7* (lift & drag ratios
lift coefficient at angle of attack 0° :0.10 [ ]
lift coefficient at max. angle of attack : 1.15 [ ]
lift coefficient at max.speed : 0.30 [ ]
induced drag coefficient at max.speed : 0.0060 [ ]
drag coefficient at max.speed : 0.0456 [ ]
drag coefficient (zero lift) : 0.0396 [ ]
calculation : *8* (speeds
stalling speed at sea-level (OW): 77 [km/u]
landing speed at sea-level (OW without bombload): 92 [km/hr]
min.drag speed (max endurance) : 107 [km/hr] at 2515 [m](power :50 [%])
min. power speed (max range) : 118 [km/hr] at 2515 [m] (power:55 [%])
max.rate of climb speed : 95.8 [km/hr] at sea-level
cruising speed : 137 [km/hr] op 2515 [m] (power:68 [%])
design speed prop : 144 [km/hr]
maximum speed : 152 [km/hr] op 100 [m] (power:99 [%])
climbing speed at sea-level (without bombload) : 185 [m/min]
calculation : *9* (regarding various performances)
take-off distance at sea-level : 229 [m]
lift/drag ratio : 9.61 [ ]
max. practical ceiling : 5025 [m] with flying weight :1007 [kg]
practical ceiling (operational weight): 4050 [m] with flying weight :1164 [kg]
practical ceiling fully loaded (mtow- 1 hour fuel) : 3225 [m] with flying weight :1300 [kg]
published ceiling (5030 [m]
climb to 1500m (without bombload) : 9.20 [min]
climb to 3000m (without bombload) : 23.74 [min]
max.dive speed : 381.5 [km/hr] at 2225 [m] height
load factor at max.angle turn 1.73 ["g"]
turn radius at 500m: 61 [m]
time needed for 360* turn 13.2 [seconds] at 500m
calculation *10* (action radius & endurance)
operational endurance : 4.61 [hours] with 2 crew and 100 [kg] useful (bomb)load and 78.3 [%] fuel
published endurance : 5.19 [hours] with 2 crew and possible useful (bomb) load : 83 [kg] and 88.1 [%] fuel
action radius : 499 [km] with 2 crew and 20[kg] photo camera/radio transmitter or bombload
max range theoretically with additional fuel tanks for total 475 [litre] fuel : 1596 [km]
useful load with action-radius 250km : 239 [kg]
production : 32.68 [tonkm/hour]
oil and fuel consumption per tonkm : 0.99 [kg]
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Literature :
Praktisch handboek vliegtuigen deel 1 page 254
Bombers 1914-19 page 38, 115
Jane’s fighter aircraft WOI page 185f
Warplanes WOI page 36, 48
German Aircraft of the First World War. Page 198
Gray, Peter and Owen Thetford. London: Putnam & Company, 1962.
Heydemarck, Georg Wilhelm. Double-Decker C.666. London: John Hamilton, Ltd, 1934.
They fought for the sky page 73
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.
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(c) B van der Zalm 04 January 2019 contact : info.aircraftinvestigation@gmail.com python 3.7.4