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weight and performance calculations for the Caudron R.4
Caudron R.4
role : armed reconnaissance and artillery observation
importance : ***
first flight : operational : July 1916
country : France
design : René Caudron
production : 249 aircraft
general information :
Gaston Caudron crashed with a R.4 on 12 December 1915 during a test flight and is killed. The R.4 was well armed and it’s crews succeeded in downing several enemy planes.
However production aircraft began to reveal certain structural weakness.
Climb rate was not impressive and a few aircraft were built with more powerful 112 KW (150 hp) Hispano Suiza 8Aa engines
The R.4 performed well in the reconnaissance role and managed to shoot down a considerable number of enemy aircraft. In early use Escadrille C.46 had claimed 34 German aircraft brought down with its R.4s in an eight-week period, but it was clear that an improved ceiling and greater manoeuvrability were necessary. Production of the R.4 ended after 249 had been built.[4] In the reconnaissance escadrilles it was progressively replaced by Sopwith 1 A.2s, SPAD XIs, Breguet 14s and Letord 1s in 1917 and 1918.
users : France
crew : 3
armament : 4 movable 7.70 [mm] (0.303 in) Lewis machine-guns
engine : 2 Renault 12 Db liquid-cooled 12 -cylinder V-engine 130 [hp](95.6 KW)
dimensions :
wingspan : 21.13 [m], length : 11.75 [m], height : 3.2[m]
wing area : 72.4 [m^2]
weights :
max.take-off weight : 2330 [kg]
empty weight operational : 1680 [kg] bombload : 100 [kg]
performance :
maximum speed : 136 [km/hr] at sea-level
climbing speed : 114 [m/min]
service ceiling : 4600 [m]
endurance : 3.0 [hours]
estimated action radius : 184 [km]
description :
4-bay biplane with fixed landing gear with nosewheel and tail strut
two spar upper and lower wing
engines and landing gear attached to the wings, fuel and bombload in or attached to fuselage
airscrew :
two fixed pitch 2 -bladed tractor airscrews with max. efficiency :0.63 [ ]
estimated diameter airscrew 2.65 [m]
angle of attack prop : 13.61 [ ]
fine pitch
reduction : 1.00 [ ]
airscrew revs : 1500 [r.p.m.]
pitch at Max speed 1.51 [m]
blade-tip speed at Vmax and max revs. : 212 [m/s]
calculation : *1* (dimensions)
mean wing chord : 1.71 [m]
calculated wing chord (rounded tips): 1.82 [m]
wing aspect ratio : 12.33 []
estimated gap : 1.85 [m]
gap/chord : 1.08 [ ]
seize (span*length*height) : 794 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 4.0 [kg/hr]
fuel consumption(cruise speed) : 54.9 [kg/hr] (74.9 [litre/hr]) at 66 [%] power
distance flown for 1 kg fuel : 2.23 [km/kg]
estimated total fuel capacity : 255 [litre] (187 [kg])
calculation : *3* (weight)
weight engine(s) dry : 500.0 [kg] = 2.61 [kg/KW]
weight 21 litre oil tank : 1.8 [kg]
oil tank filled with 1.4 litre oil : 1.3 [kg]
oil in engine 11 litre oil : 9.6 [kg]
fuel in engine 1 litre fuel : 1.0 [kg]
weight 32 litre gravity patrol tank(s) : 4.8 [kg]
weight radiator : 27.4 [kg]
weight exhaust pipes & fuel lines 12.2 [kg]
R4 with 140 hp Hispano Suiza engines
weight cowling 3.8 [kg]
weight airscrew(s) (wood) incl. boss & bolts : 38.0 [kg]
total weight propulsion system : 598 [kg](25.7 [%])
***************************************************************
fuselage skeleton (wood gauge : 9.19 [cm]): 254 [kg]
bracing : 21.1 [kg]
fuselage covering ( 26.1 [m2] doped linen fabric) : 8.3 [kg]
weight controls + indicators: 8.4 [kg]
weight seats : 9.0 [kg]
weight other details, lighting set, etc. : 9.1 [kg]
weight bomb storage : 7.0 [kg]
weight two 112 [litre] main fuel tanks empty : 17.9 [kg]
weight interior + equipment + fuel lines: 43 [kg]
total weight fuselage : 378 [kg](16.2 [%])
***************************************************************
weight wing covering (doped linen fabric) : 46 [kg]
total weight ribs (111 ribs) : 138 [kg]
weight engine mounts : 10 [kg]
load on front upper spar (clmax) per running metre : 748.5 [N]
load on rear upper spar (vmax) per running metre : 301.2 [N]
total weight 8 spars : 132 [kg]
weight wings : 317 [kg]
weight wing/square meter : 4.38 [kg]
weight 16 interplane struts & cabane : 52.8 [kg]
weight cables (139 [m]) : 33.3 [kg] (= 239 [gram] per metre)
diameter cable : 6.2 [mm]
weight fin & rudder (5.2 [m2]) : 23.5 [kg]
weight stabilizer & elevator (8.1 [m2]): 36.2 [kg]
total weight wing surfaces & bracing : 472 [kg] (20.3 [%])
*******************************************************************
weight machine-gun(s) : 50.8 [kg]
weight pivot mounting mg :24.0 [kg]
weight armament : 75 [kg]
********************************************************************
wheel pressure : 512.6 [kg]
weight 5 wheels (690 [mm] by 81 [mm]) : 47.3 [kg]
weight tailskid : 5.0 [kg]
weight undercarriage with axle 63.0 [kg]
total weight landing gear : 115.3 [kg] (4.9 [%]
*******************************************************************
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calculated empty weight : 1638 [kg](70.3 [%])
weight oil for 3.6 hours flying : 14.5 [kg]
weight cooling fluids : 41.3 [kg]
weight 20 drums empty : 4.1 [kg]
weight ammunition (940 rounds) : 29.9 [kg]
weight automatic pistol with spare magazines : 1.2 [kg]
*******************************************************************
calculated operational weight empty : 1725 [kg] (74.0 [%])
published operational weight empty : 1680 [kg] (72.1 [%])
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weight crew : 243 [kg]
weight fuel for 2.0 hours flying : 110 [kg]
********************************************************************
operational weight : 2078 [kg](89.2 [%])
bomb load : 100 [kg]
operational weight bombing mission : 2178 [kg]
weight camera : 20 [kg]
operational weight photo mission : 2098 [kg]
fuel reserve : 77 [kg] enough for 1.41 [hours] flying
possible additional useful load : 155 [kg]
operational weight fully loaded : 2330 [kg] with fuel tank filled for 100 [%]
published maximum take-off weight : 2330 [kg] (100.0 [%])
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calculation : * 4 * (engine power)
power loading (operational without bombload) : 10.87 [kg/kW]
total power : 191.2 [kW] at 1500 [r.p.m]
calculation : *5* (loads)
manoeuvre load : 1.8 [g] at 1000 [m]
Caudron R 4 qui équipa l'escadrille 46 du 13 juin 1916 à la mi 1917 - Carte postale d'époque.
limit load : 3.75 [g] ultimate load : 5.6 [g] load factor : 1.9 [g]
design flight time : 2.40 [hours]
design cycles : 271 sorties, design hours : 650 [hours]
operational wing loading : 284 [N/m^2]
wing stress (3 g) during operation : 195 [N/kg] at 3g emergency manoeuvre
calculation : *6* (angles of attack)
angle of attack zero lift : -1.07 ["]
max. angle of attack (stalling angle) : 10.38 ["]
angle of attack at max. speed : 2.38 ["]
calculation : *7* (lift & drag ratios
lift coefficient at angle of attack 0° :0.10 [ ]
lift coefficient at max. angle of attack : 1.07 [ ]
lift coefficient at max. speed : 0.32 [ ]
induced drag coefficient at max. speed : 0.0048 [ ]
drag coefficient at max. speed : 0.0504 [ ]
drag coefficient (zero lift) : 0.0457 [ ]
calculation : *8* (speeds
stalling speed at sea-level (OW): 75 [km/u]
landing speed at sea-level (OW without bombload): 90 [km/hr]
min. drag speed (max endurance) = minimum speed*1.1 at cruise height : 92 [km/hr] at 2300 [m] (power:43 [%])
min. power speed (max range) : 92 [km/hr] at 2300 [m] (power:43 [%])
max. rate of climb speed : 82.9 [km/hr] at sea-level
cruising speed : 122 [km/hr] op 2300 [m] (power:66 [%])
design speed prop : 129 [km/hr]
maximum speed : 136 [km/hr] op 0 [m] (power:100 [%])
climbing speed at sea-level (without bombload) : 183 [m/min]
calculation : *9* (regarding various performances)
take-off distance at sea-level : 200 [m]
lift/drag ratio : 10.92 [ ]
max. practical ceiling : 5300 [m] with flying weight :1802 [kg]
practical ceiling (operational weight): 4450 [m] with flying weight :2078 [kg]
practical ceiling fully loaded (mtow- 1 hour fuel) : 3875 [m] with flying weight :2275 [kg]
published ceiling (4600 [m]
climb to 1500m (without bombload) : 9.21 [min]
climb to 3000m (without bombload) : 22.90 [min]
max. dive speed : 376.7 [km/hr] at 2875 [m] height
load factor at max. angle turn 1.96 ["g"]
turn radius at 500m: 54 [m]
time needed for 360* turn 11.4 [seconds] at 500m
calculation *10* (action radius & endurance)
operational endurance : 3.41 [hours] with 3 crew and 175 [kg] useful (bomb)load and 100.0 [%] fuel
published endurance : 3.00 [hours] with 3 crew and possible useful (bomb) load : 197 [kg] and 88.1 [%] fuel
action radius : 381 [km] with 3 crew and 20[kg] photo camera/radio transmitter or bombload
max range theoretically with additional fuel tanks for total 775 [litre] fuel : 1266 [km]
useful load with action-radius 250km : 343 [kg]
production : 42.04 [tonkm/hour]
oil and fuel consumption per tonkm : 1.40 [kg]
Literature :
Warplanes WW1 page 96
Jane’s FAWOI page 109
Wikipedia
http://albindenis.free.fr/Site_escadrille/escadrille046.htm
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 23 November 2019 contact : info.aircraftinvestigation@gmail.com python 3.7.4