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Martinsyde G.102 Elephant light bomber biplane weight and performance calculations; photogallery and facts
Martinsyde G.102 Elephant
role : light bomber
first flight : operational : September 1916
country : United-Kingdom
design :
production : 171 aircraft
general information :
More powerful version with 160 hp engine. Used as day bomber. It was not suited for night raids because there was no observer/gunner to help with navigation and bomb aiming. Good speed & endurance for daylight raids. It was one of the few RFC aircraft that could carry a 3 cwt bomb, 336 lbs (152 kg) RAF bomb. The 1.5m long HE Heavy Case bomb was carried beneath the fuselage.
users : RFC
crew : 1
armament : 1 fixed 7.70 [mm] (0.303 in) Lewis machine-gun on top plane
and 1 fixed pillar mounted 7.70 [mm] (0.303 in) Lewis machine-gun aft of the cockpit
pointing rearwards
engine : 1 Beardmore liquid-cooled 6 -cylinder inline engine 160 [hp](117.7 KW)
dimensions :
wingspan : 11.58 [m], length : 8.23 [m], height : 2.94[m]
wing area : 38.09 [m^2]
weights :
max.take-off weight : 1221 [kg]
empty weight operational : 813 [kg] bombload : 150 [kg]
performance :
maximum speed : 166 [km/hr] at sea-level
climbing speed : 165 [m/min]
service ceiling : 3901 [m]
endurance : 4.5 [hours]
estimated action radius : 336 [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 :0.66 [ ]
estimated diameter airscrew 2.70 [m]
angle of attack prop : 19.18 [ ]
reduction : 1.00 [ ]
airscrew revs : 1250 [r.p.m.]
pitch at Max speed 2.21 [m]
blade-tip speed at Vmax and max revs. : 183 [m/s]
calculation : *1* (dimensions)
mean wing chord : 1.64 [m]
calculated wing chord (rounded tips): 1.83 [m]
wing aspect ratio : 7.04 []
estimated gap : 1.50 [m]
gap/chord : 0.91 [ ]
seize (span*length*height) : 280 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 2.5 [kg/hr]
fuel consumption(cruise speed) : 30.6 [kg/hr] (41.8 [litre/hr]) at 65 [%] power
distance flown for 1 kg fuel : 4.88 [km/kg]
estimated total fuel capacity : 214 [litre] (157 [kg])
calculation : *3* (weight)
weight engine(s) dry : 279.0 [kg] = 2.37 [kg/KW]
weight 18 litre oil tank : 1.5 [kg]
oil tank filled with 0.9 litre oil : 0.8 [kg]
oil in engine 7 litre oil : 5.9 [kg]
fuel in engine 1 litre fuel : 0.6 [kg]
weight 18 litre gravity patrol tank(s) : 2.7 [kg]
weight radiator : 16.9 [kg]
weight exhaust pipes & fuel lines 14.4 [kg]
weight cowling 4.7 [kg]
weight airscrew(s) (wood) incl. boss & bolts : 19.0 [kg]
total weight propulsion system : 344 [kg](28.2 [%])
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fuselage skeleton (wood gauge : 6.45 [cm]): 88 [kg]
bracing : 5.1 [kg]
fuselage covering ( 12.8 [m2] doped linen fabric) : 4.1 [kg]
weight controls + indicators: 6.2 [kg]
weight seats : 3.0 [kg]
weight other details, lighting set, etc. : 5.1 [kg]
weight bomb storage : 10.5 [kg]
weight periscopic bomb sight : 2.1 [kg]
weight 196 [litre] main fuel tank empty : 15.7 [kg]
weight engine mounts & firewalls : 6 [kg]
total weight fuselage : 145 [kg](11.9 [%])
***************************************************************
weight wing covering (doped linen fabric) : 24 [kg]
total weight ribs (61 ribs) : 73 [kg]
load on front upper spar (clmax) per running metre : 678.8 [N]
load on rear upper spar (vmax) per running metre : 290.5 [N]
total weight 8 spars : 52 [kg]
weight wings : 149 [kg]
weight wing/square meter : 3.91 [kg]
weight 8 interplane struts & cabane : 14.9 [kg]
weight cables (68 [m]) : 5.6 [kg] (= 82 [gram] per metre)
diameter cable : 3.7 [mm]
weight fin & rudder (1.6 [m2]) : 6.3 [kg]
weight stabilizer & elevator (4.3 [m2]): 17.1 [kg]
total weight wing surfaces & bracing : 193 [kg] (15.8 [%])
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weight machine-gun(s) : 25.4 [kg]
cranked pillar mounting :2.0 [kg]
weight quadrant mounting and Bowden cable : 1.5 [kg]
weight Aldis gunsight : 0.8 [kg]
weight armament : 30 [kg]
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wheel pressure : 610.5 [kg]
weight 2 wheels (750 [mm] by 94 [mm]) : 27.8 [kg]
weight tailskid : 2.5 [kg]
weight undercarriage with axle 33.1 [kg]
total weight landing gear : 63.4 [kg] (5.2 [%]
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calculated empty weight : 775 [kg](63.5 [%])
weight oil for 5.4 hours flying : 13.3 [kg]
weight cooling fluids : 25.4 [kg]
weight 5 drums empty : 1.0 [kg]
weight ammunition (470 rounds) : 13.9 [kg]
weight automatic pistol with spare magazines : 1.2 [kg]
*******************************************************************
calculated operational weight empty : 829 [kg] (67.9 [%])
published operational weight empty : 813 [kg] (66.6 [%])
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weight crew : 81 [kg]
weight fuel for 2.0 hours flying : 61 [kg]
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operational weight : 971 [kg](79.6 [%])
bomb load : 150 [kg]
operational weight bombing mission : 1121 [kg]
fuel reserve : 95 [kg] enough for 3.11 [hours] flying
possible additional useful load : 4 [kg]
operational weight fully loaded : 1221 [kg] with fuel tank filled for 100 [%]
published maximum take-off weight : 1221 [kg] (100.0 [%])
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calculation : * 4 * (engine power)
power loading (Take-off) : 10.38 [kg/kW]
total power : 117.7 [kW] at 1250 [r.p.m]
calculation : *5* (loads)
manoeuvre load : 3.0 [g] at 1000 [m]
limit load : 3.0 [g] ultimate load : 4.5 [g] load factor : 1.8 [g]
design flight time : 3.60 [hours]
design cycles : 306 sorties, design hours : 1100 [hours]
wing loading (MTOW) : 314 [N/m^2]
wing stress (3 g) during operation : 221 [N/kg] at 3g emergency manoeuvre
calculation : *6* (angles of attack)
angle of attack zero lift : -1.45 ["]
max. angle of attack (stalling angle) : 12.38 ["]
angle of attack at max. speed : 0.89 ["]
calculation : *7* (lift & drag ratios
lift coefficient at angle of attack 0° :0.12 [ ]
lift coefficient at max. angle of attack : 1.15 [ ]
lift coefficient at max. speed : 0.19 [ ]
induced drag coefficient at max. speed : 0.0030 [ ]
drag coefficient at max. speed : 0.0339 [ ]
drag coefficient (zero lift) : 0.0308 [ ]
calculation : *8* (speeds
stalling speed at sea-level (OW): 68 [km/u]
landing speed at sea-level (OW without bombload): 82 [km/hr]
min. drag speed (max endurance) : 102 [km/hr] at 1950 [m](power :39 [%])
min. power speed (max range) : 108 [km/hr] at 1950 [m] (power:41 [%])
max. rate of climb speed : 100.6 [km/hr] at sea-level
cruising speed : 149 [km/hr] op 1950 [m] (power:66 [%])
design speed prop : 158 [km/hr]
maximum speed : 166 [km/hr] op 100 [m] (power:98 [%])
climbing speed at sea-level (without bombload) : 258 [m/min]
calculation : *9* (regarding various performances)
take-off distance at sea-level : 196 [m]
lift/drag ratio : 10.04 [ ]
max. practical ceiling : 4350 [m] with flying weight :910 [kg]
practical ceiling (operational weight): 4050 [m] with flying weight :971 [kg]
practical ceiling fully loaded (mtow- 1 hour fuel) : 3050 [m] with flying weight :1190 [kg]
published ceiling (3901 [m]
climb to 1500m (without bombload) : 6.67 [min]
climb to 3000m (without bombload) : 17.66 [min]
max. dive speed : 403.9 [km/hr] at 2050 [m] height
load factor at max. angle turn 1.74 ["g"]
turn radius at 500m: 54 [m]
time needed for 360* turn 12.3 [seconds] at 500m
calculation *10* (action radius & endurance)
operational endurance : 5.11 [hours] with 1 crew and 154 [kg] bombload and 100.0 [%] fuel
published endurance : 4.50 [hours] with 1 crew and possible useful (bomb) load : 173 [kg] and 88.1 [%] fuel
action radius : 709 [km] with 1 crew and 20[kg] photo camera/radio transmitter or bombload
max range theoretically with additional fuel tanks for total 445 [litre] fuel : 1589 [km]
useful load with action-radius 250km : 208 [kg]
production : 31.11 [tonkm/hour]
oil and fuel consumption per tonkm : 1.06 [kg]
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Literature :
Praktisch handboek vliegtuigen deel 1 page 188
Warplanes WW1 page 95
Fighters 1914-19 page 44
Armament of British Aircraft 1909-1939 page 267
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 03 November 2019 contact : info.aircraftinvestigation@gmail.com python 3.7.4