FBA type C calculations| aircraft investigation info

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weight and performance calculations for the F.B.A. type C

F.B.A. type C

role : light maritime two-seat patrol aircraft, ASW

importance : ***

first flight : operational : April 1916

country : France

design : Louis Schreck

production : 78 aircraft

general information :

The Franco British Aviation Company produced a range of successful flying boat’s during WOI. The mostly French company (there was only an office in London) started building Leveque-type flying boats before WOI. In 1915 the 2-seat Type B appeared fitted with a 100 hp Gnome rotary engine. This was used by the French Navy and the RNAS (124 aircraft). The RNAS had still 24 type B’s in use in January 1919 ! In April 1916 the type B was followed by the type C, very similar, but now with a 130 hp Clerget engine. Later followed the Type H the most built version. 982 type H’s were built under license in Italy alone.

Users : French, Italian and Russian navy

crew : 2

armament : 1 movable 7.70 [mm] (0.303 in) Lewis machine-gun for the observer

engine : 1 Clerget 9B air-cooled 9 -cylinder two-valve rotary engine 130 [hp](95.6 KW)

dimensions :

wingspan : 13.7 [m], length : 8.79 [m], height : 3.4[m]

wing area : 30.0 [m^2]

weights :

max.take-off weight : 940 [kg]

empty weight operational : 0 [kg] bombload : 24 [kg]

performance :

maximum speed : 113 [km/hr] at sea-level

service ceiling : 3700 [m]

estimated action radius : 150 [km]

description :

2½-bay biplane flying boat

2 (aid) tip floats

upper wingtips supported by slanted struts

two spar upper and lower wing

engine attached to top plane

airscrew :

fixed pitch 4 -bladed pusher airscrew with max. efficiency :0.57 [ ]

estimated diameter airscrew 2.33 [m]

angle of attack prop : 15.35 [ ]

reduction : 1.00 [ ]

airscrew revs : 1250 [r.p.m.]

pitch at Max speed 1.51 [m]

blade-tip speed at Vmax and max revs. : 156 [m/s]

calculation : *1* (dimensions)

mean wing chord : 1.25 [m]

calculated wing chord (rounded tips): 1.37 [m]

wing aspect ratio : 10.95 []

estimated gap : 1.58 [m]

gap/chord : 1.26 [ ]

seize (span*length*height) : 409 [m^3]

calculation : *2* (fuel consumption)

oil consumption : 6.0 [kg/hr]

fuel consumption(cruise speed) : 30.7 [kg/hr] (41.8 [litre/hr]) at 70 [%] power

distance flown for 1 kg fuel : 3.32 [km/kg]

estimated total fuel capacity : 140 [litre] (103 [kg])

calculation : *3* (weight)

weight engine(s) dry : 173.0 [kg] = 1.81 [kg/KW]

weight 26 litre oil tank : 3.3 [kg]

oil tank filled with 0.7 litre oil : 0.6 [kg]

oil in engine 1 litre oil : 0.5 [kg]

fuel in engine 1 litre fuel : 0.5 [kg]

weight 18 litre gravity patrol tank(s) : 1.7 [kg]

weight cowling 3.8 [kg]

weight airscrew(s) (wood) incl. boss & bolts : 33.5 [kg]

total weight propulsion system : 214 [kg](22.7 [%])

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fuselage skeleton (wood gauge : 5.11 [cm]): 59 [kg]

bracing : 4.5 [kg]

plywood/wood covering hull (gauche : 1.3 [cm]): 117.9 [kg]

weight controls + indicators: 6.7 [kg]

weight seats : 6.0 [kg]

weight other details, lighting set, etc. : 5.1 [kg]

weight bomb storage : 1.7 [kg]

weight 122 [litre] main fuel tank empty : 11.7 [kg]

weight engine mounts & firewalls : 5 [kg]

total weight fuselage : 217 [kg](23.1 [%])

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

weight wing covering (doped linen fabric) : 19 [kg]

total weight ribs (61 ribs) : 56 [kg]

load on front upper spar (clmax) per running metre : 505.6 [N]

load on rear upper spar (vmax) per running metre : 195.7 [N]

total weight 8 spars : 53 [kg]

weight wings : 129 [kg]

weight wing/square meter : 4.28 [kg]

weight 12 interplane struts & cabane : 26.0 [kg]

weight cables (66 [m]) : 5.6 [kg] (= 84 [gram] per metre)

diameter cable : 3.7 [mm]

weight fin & rudder (2.2 [m2]) : 9.7 [kg]

weight stabilizer & elevator (2.9 [m2]): 12.5 [kg]

total weight wing surfaces & bracing : 182 [kg] (19.4 [%])

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weight machine-gun(s) : 12.7 [kg]

weight pivot mounting mg :6.0 [kg]

weight armament : 19 [kg]

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weight 2 tip floats : 9 [kg] (0.9 [%])

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calculated empty weight : 640 [kg](68.1 [%])

weight oil for 3.5 hours flying : 21.3 [kg]

weight 5 drums empty : 1.0 [kg]

weight ammunition (235 rounds) : 7.5 [kg]

weight automatic pistol with spare magazines : 1.2 [kg]

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

calculated operational weight empty : 670 [kg] (71.3 [%])

estimated operational weight empty : 650 [kg] (69.2 [%])

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~U~

weight crew : 162 [kg]

weight fuel for 2.0 hours flying : 61 [kg]

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operational weight : 894 [kg](95.1 [%])

bomb load : 24 [kg]

operational weight bombing mission : 918 [kg]

fuel reserve : 22 [kg] enough for 0.72 [hours] flying

operational weight fully loaded : 940 [kg] with fuel tank filled for 81 [%]

published maximum take-off weight : 940 [kg] (100.0 [%])

=||I>|

calculation : * 4 * (engine power)

power loading (operational without bombload) : 9.35 [kg/kW]

total power : 95.6 [kW] at 1250 [r.p.m]

calculation : *5* (loads)

manoeuvre load : 1.3 [g] at 1000 [m]

limit load : 3.5 [g] ultimate load : 5.2 [g] load factor : 1.9 [g]

design flight time : 2.36 [hours]

design cycles : 339 sorties, design hours : 800 [hours]

operational wing loading : 292 [N/m^2]

wing stress (3 g) during operation : 205 [N/kg] at 3g emergency manoeuvre

calculation : *6* (angles of attack)

angle of attack zero lift : -1.09 ["]

max. angle of attack (stalling angle) : 10.98 ["]

angle of attack at max. speed : 4.25 ["]

calculation : *7* (lift & drag ratios

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

lift coefficient at max. angle of attack : 1.10 [ ]

lift coefficient at max. speed : 0.49 [ ]

induced drag coefficient at max. speed : 0.0093 [ ]

drag coefficient at max. speed : 0.0952 [ ]

drag coefficient (zero lift) : 0.0859 [ ]

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 : 90 [km/hr] at 1850 [m] (power:54 [%])

min. power speed (max range) : 90 [km/hr] at 1850 [m] (power:54 [%])

cruising speed : 102 [km/hr] op 1850 [m] (power:67 [%])

design speed prop : 107 [km/hr]

maximum speed : 113 [km/hr] op 100 [m] (power:99 [%])

climbing speed at sea-level (without bombload) : 188 [m/min]

calculation : *9* (regarding various performances)

take-off distance at sea-level : 173 [m]

lift/drag ratio : 8.66 [ ]

max. practical ceiling : 4775 [m] with flying weight :758 [kg]

practical ceiling (operational weight) : 3750 [m] with flying weight :894 [kg] line 3385

practical ceiling fully loaded (mtow- 1 hour fuel) : 3625 [m] with flying weight :909 [kg]

published ceiling (3700 [m]

climb to 1500m (without bombload) : 9.12 [min]

climb to 3000m (without bombload) : 24.21 [min]

max. dive speed : 257.1 [km/hr] at 2625 [m] height

load factor at max. angle turn 1.72 ["g"]

turn radius at 500m: 57 [m]

time needed for 360* turn 12.8 [seconds] at 500m

calculation *10* (action radius & endurance)

operational endurance : 2.85 [hours] with 2 crew and 20 [kg] useful load and 85.2 [%] fuel

published endurance : 2.95 [hours] with 2 crew and possible useful (bomb) load : 17 [kg] and 88.1 [%] fuel

action radius : 145 [km] with 2 crew and 20[kg] photo camera/radio transmitter or bombload

max range theoretically with additional fuel tanks for total 269 [litre] fuel : 654 [km]

useful load with action-radius 250km : 46 [kg]

production : 4.72 [tonkm/hour]

oil and fuel consumption per tonkm : 7.77 [kg]

-°°_I /

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Literature :

https://en.wikipedia.org/wiki/FBA_Type_A

Bombers 1914-19 page 168

Praktisch handboek vliegtuigen deel 1 page 139

Jane’s Fighting aircraft WWI page 68, 114

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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