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weight and performance calculations for the Caproni Ca.4 (Ca.42)
Caproni Ca.4 (Ca.42)
role : heavy bomber
importance : ***
first flight : end 1917 operational : March 1918
country : Italy
design :
production : 23 aircraft
general information :
The Ca.40 triplane-bomber first flew in 1916. With three 200 hp Isotta-Fraschini engines it was underpowered and only 3 aircraft were built. It was followed by the Ca.41 with more powerful 250 hp engines (41 built) with the pilots seated in tandem and the Ca.42 with 270 hp engines and the pilots seated side by side. The Ca.42 had a coffin-shaped bomb container attached to the lower wing. 6 bombers were handed to the RNAS 227 sq, but they were not used operational by the British.
Chord : 2.13m climb to 1981m : 14 min
users : Italy, RNAS
crew : 5
armament : 4 movable 7.70 [mm] (0.303 in) Lewis machine-guns
engine : 3 Isotta Fraschini V.6B liquid-cooled 6-cylinder inline engine 270 [hp]
(198.6KW)
dimensions :
wingspan : 29.87 [m], length : 15.1 [m], height : 6.3[m]
wing area : 200.0 [m^2]
weights :
max.take-off weight : 7484 [kg]
empty weight operational (estimation): 5200.0 [kg] bombload : 1360 [kg]
performance :
maximum speed : 140 [km/hr] at sea-level
service ceiling : 3000 [m]
endurance : 7.0 [hours]
estimated action radius : 441 [km]
description :
6-bay triplane with fixed underwing 16 -wheel landing gear and tail strut
two spar upper and lower wing
tail supported by two fabric/plywood covered tail booms
2 engines attached to the wings 1 in the fuselage, landing gear attached to the wings, bombload attached to fuselage
two fuel tanks in the tail booms, one fuel tank in the fuselage 
airscrew :
two fixed pitch 2 -bladed tractor airscrews and one fixed pitch pusher propeller with max. efficiency :0.64 [ ]
estimated diameter airscrew 2.79 [m]
angle of attack prop : 11.16 [ ]
fine pitch
reduction : 1.00 [ ]
airscrew revs : 1800 [r.p.m.]
pitch at Max speed 1.30 [m]
blade-tip speed at Vmax and max revs. : 266 [m/s]
calculation : *1* (dimensions)
mean wing chord : 2.23 [m]
calculated wing chord (rounded tips): 2.31 [m]
wing aspect ratio : 13.38 []
Some Ca.42’s were powered with 400 hp Liberty engines in 1918. Probably only operational in autumn 1918, short before the end of WWI.
estimated gap : 2.26 [m]
gap/chord : 1.01 [ ]
seize (span*length*height) : 2842 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 8.9 [kg/hr]
fuel consumption(cruise speed) : 158.3 [kg/hr] (216.0 [litre/hr]) at 74 [%] power
distance flown for 1 kg fuel : 0.80 [km/kg]
estimated total fuel capacity : 1716 [litre] (1258 [kg])
calculation : *3* (weight)
weight engine(s) dry : 1251.1 [kg] = 2.10 [kg/KW]
weight 99 litre oil tank : 8.4 [kg]
oil tank filled with 4.5 litre oil : 4.0 [kg]
oil in engine 33 litre oil : 29.8 [kg]
fuel in engine 4 litre fuel : 3.0 [kg]
weight 92 litre gravity patrol tank(s) : 13.8 [kg]
weight radiator : 85.4 [kg]
weight exhaust pipes & fuel lines 30.1 [kg]
weight self-starter : 4.9 [kg]
weight cowling 7.9 [kg]
weight airscrew(s) (wood) incl. boss & bolts : 89.4 [kg]
total weight propulsion system : 1519 [kg](20.3 [%])
***************************************************************
tail boom plywood covering (monocoque) : 121 [kg]
fuselage skeleton (wood gauge : 8.46 [cm]): 565 [kg]
bracing : 60.2 [kg]
fuselage covering ( 60.3 [m2] doped linen fabric) : 19.3 [kg]
weight controls + indicators: 10.4 [kg]
weight seats : 15.0 [kg]
weight other details, lighting set, etc. : 13.1 [kg]
weight bomb storage : 95.2 [kg]
weight bomb sight : 1.2 [kg]
weight 541 [litre] main fuel tank empty : 43.3 [kg]
additional in each tail boom a 541 [litre] fuel tank empty : 86.6 [kg]
weight interior + equipment + fuel lines: 206 [kg]
weight engine mount and firewall : 10 [kg]
total weight fuselage : 1246 [kg](16.6 [%])
***************************************************************
weight wing covering (doped linen fabric) : 128 [kg]
total weight ribs (274 ribs) : 445 [kg]
weight engine mounts : 20 [kg]
load on front upper spar (clmax) per running metre : 1633.1 [N]
load on rear upper spar (vmax) per running metre : 646.4 [N]
total weight 12 spars : 610 [kg]
weight wings : 1183 [kg]
weight wing/square meter : 5.92 [kg]
weight 48 interplane struts & cabane : 324.7 [kg]
weight cables (229 [m]) : 146.7 [kg] (= 641 [gram] per metre)
diameter cable : 10.2 [mm]
weight fin & rudder (10.4 [m2]) : 62.8 [kg]
weight stabilizer & elevator (22.5 [m2]): 134.6 [kg]
total weight wing surfaces & bracing : 1872 [kg] (25.0 [%])
*******************************************************************
weight machine-gun(s) : 50.8 [kg]
weight pivot mounting mg :24.0 [kg]
weight armament : 75 [kg]
********************************************************************
good soft ground capabilities
wheel pressure : 467.8 [kg]
weight 16 wheels (850 [mm] by 113 [mm]) : 235.2 [kg]
weight tailskid : 8.6 [kg]
weight undercarriage with axle 109.7 [kg]
total weight landing gear : 353.6 [kg] (4.7 [%]
*******************************************************************
Ca.42 note the positions for 5 crew members
********************************************************************
calculated empty weight : 5066 [kg](67.7 [%])
weight oil for 8.4 hours flying : 75.1 [kg]
weight cooling fluids : 128.7 [kg]
weight 20 drums empty : 4.1 [kg]
weight ammunition (940 rounds) : 29.9 [kg]
weight signal pistol with cartridges : 3.6 [kg]
weight automatic pistol with spare magazines : 1.2 [kg]
*******************************************************************
calculated operational weight empty : 5304 [kg] (70.9 [%])
estimated operational weight empty : 5200 [kg] (69.5 [%])
_____________
" "
weight crew : 405 [kg]
weight fuel for 2.0 hours flying : 317 [kg]
********************************************************************
operational weight : 6026 [kg](80.5 [%])
bomb load : 1360 [kg]
operational weight bombing mission : 7386 [kg]
fuel reserve : 98 [kg] enough for 0.62 [hours] flying
operational weight fully loaded : 7484 [kg] with fuel tank filled for 33 [%]
published maximum take-off weight : 7484 [kg] (100.0 [%])
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calculation : * 4 * (engine power)
power loading (Take-off) : 12.56 [kg/kW]
total power : 595.8 [kW] at 1800 [r.p.m]
calculation : *5* (loads)
manoeuvre load : 1.4 [g] at 1000 [m]
limit load : 3.0 [g] ultimate load : 4.5 [g] load factor : 1.9 [g]
Only 3 Ca.40 were built. They were fitted with a nosewheel under carriage. From this the Ca.41 and Ca.42 evolved.
design flight time : 4.90 [hours]
design cycles : 306 sorties, design hours : 1500 [hours]
wing loading (MTOW) : 367 [N/m^2]
wing stress (3 g) during operation : 184 [N/kg] at 3g emergency manoeuvre
calculation : *6* (angles of attack)
angle of attack zero lift : -1.06 ["]
max. angle of attack (stalling angle) : 9.92 ["]
angle of attack at max. speed : 2.35 ["]
calculation : *7* (lift & drag ratios
lift coefficient at angle of attack 0° :0.10 [ ]
lift coefficient at max. angle of attack : 1.04 [ ]
lift coefficient at max. speed : 0.32 [ ]
induced drag coefficient at max. speed : 0.0045 [ ]
drag coefficient at max. speed : 0.0526 [ ]
drag coefficient (zero lift) : 0.0481 [ ]
calculation : *8* (speeds
stalling speed at sea-level (OW): 78 [km/u]
landing speed at sea-level (OW without bombload): 93 [km/hr]
min. drag speed (max endurance) = minimum speed*1.1 at cruise height : 92 [km/hr] at 1500 [m] (power:41 [%])
min. power speed (max range) : 92 [km/hr] at 1500 [m] (power:41 [%])
max. rate of climb speed : 84.5 [km/hr] at sea-level
cruising speed : 126 [km/hr] op 1500 [m] (power:68 [%])
design speed prop : 133 [km/hr]
maximum speed : 140 [km/hr] op 100 [m] (power:99 [%])
climbing speed at sea-level (without bombload) : 204 [m/min]
calculation : *9* (regarding various performances)
take-off distance at sea-level : 191 [m]
lift/drag ratio : 10.94 [ ]
max. practical ceiling : 5575 [m] with flying weight :5429 [kg]
practical ceiling (operational weight): 4900 [m] with flying weight :6026 [kg]
practical ceiling fully loaded (mtow- 1 hour fuel) : 3600 [m] with flying weight :7326 [kg]
published ceiling (3000 [m]
climb to 1500m (without bombload) : 8.14 [min]
climb to 3000m (without bombload) : 19.74 [min]
max. dive speed : 431.1 [km/hr] at 2600 [m] height
2 x 8 bogie main landing gear. This airplane has no central coffin shaped container attached to the lower wing between the wheels and therefore is probably a Ca.41.
load factor at max. angle turn 1.67 ["g"]
turn radius at 500m: 76 [m]
time needed for 360* turn 15.1 [seconds] at 500m
calculation *10* (action radius & endurance)
operational endurance : 2.62 [hours] with 5 crew and 1360 [kg] bombload and 33.0 [%] fuel
published endurance : 7.00 [hours] with 5 crew and possible useful (bomb) load : 667 [kg] and 88.1 [%] fuel
action radius : 698 [km] with 5 crew and 20[kg] photo camera/radio transmitter or bombload
max range theoretically with additional fuel tanks for total 2911 [litre] fuel : 1698 [km]
useful load with action-radius 250km : 1147 [kg]
production : 144.50 [tonkm/hour]
oil and fuel consumption per tonkm : 1.16 [kg]
Literature :
Praktisch handboek vliegtuigen deel 1 page 223,226
Bombers 1914-19 page 83
Warplanes WW1 page 70, 130, 134f
Jane’s fighting aircraft WWI page 201
Ca.41
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/
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(c) B van der Zalm 23 November 2019 contact : info.aircraftinvestigation@gmail.com python 3.7.4