Gotha G.IV
role : medium-weight bomber
first flight : operational : March 1917
country : Germany
design :
production : 230 aircraft
general information :
widely used operational. Operational use of the G.IV demonstrated that the incorporation of the fuel tanks into the engine nacelles was a mistake. In a crash landing the tanks could rupture and spill fuel onto the hot engines. This posed a serious problem because landing accidents caused 75% of operational losses. In response Gotha produced the G.V, which housed its fuel tanks inside the fuselage. The smaller engine nacelles were mounted on struts above the lower wing.
Normal bombload for raids on England was six 50 kg bombs.
March 1917 the Gotha G.IV’s arrived at Gistel afb, Belgium, they formed BOGOHL 3, the “England Geschwader” , the secret unit specially formed for the attack of London. It had 36 Gotha’s in the inventory and was under direct command of the OHL (Oberste Heeresleitung). There chief aim was, as set forth by General Ludendorff, was to score a propaganda succes. Bombs in the hart of London could so arouse the Britisch population that the government might be forced out of office and replaced by one that would sue for peace. The attack of military targets, the disruption of war industry were secondary objectives. Also it was hoped that the British were forced to withdraw aircraft, men and weapon from the front in France to the UK to defend British airspace. The last hope was more then realised also the home front moral was disturbed by the daylight raids.
It had a Görz precision bombing sight with a 90cm Zeiss telescope tube.
For its size manoeuvrability was excellent and helped defence against attackers. However light construction and poor stability with empty tanks caused many landing accidents. The operational losses (37) exceeded the combat losses (24) > this probably including the Gotha G.V. The equipment included compressed oxygen in cylinders, each crew member using a pipe stem mouthpiece rather than a mask. Later this was replaced by liquid air in insulated flasks. The crew was always frightened for ditching in the cold North Sea due to engine failure. Carrier pigeons were carried with which to send off distress messages. The bomber itself was advertised as being able to float on the water for at least 8 hours, as it had watertight compartments. But this may be doubted, and was only to boost morale of the crew. Results of the Gotha attacks was difficult to indicate. Intelligence was gathered by agents in London and Dutch & Scandinavian travellers but there reports wildly exaggerated or fabricated the inflicted damage. Chord upper wing : 2.3m lower wing : 2.2m gap : 2.17m
users: Germany
crew: 3
armament : 3 movable 7.92 [mm] (0.312 in) Parabellum MG 14 machine-guns
engine : 2 Mercedes D.IVa liquid-cooled 6 -cylinder inline engine 252 [hp](185.3 KW)
dimensions :
wingspan : 23.7 [m], length : 12.2 [m], height : 3.9[m]
wing area : 95.0 [m^2]
weights :
max.take-off weight : 3648 [kg]
empty weight operational : 2413 [kg] bombload : 500 [kg]
performance :
maximum speed : 141 [km/u] op 3658 [m]
climbing speed : 107 [m/min]
service ceiling : 5500 [m]
endurance : 6.0 [hours]
estimated action radius : 381 [km]
description :
4-bay biplane with fixed underwing 4 -wheel landing gear and tail strut
two spar upper and lower wing
engines, landing gear and fuel attached to the wings, bombload in or attached to fuselage
airscrew :
two fixed pitch 2 -bladed pusher airscrews with max. efficiency :0.64 [ ]
estimated diameter airscrew 3.12 [m]
angle of attack prop : 12.86 [ ]
fine pitch
reduction : 1.00 [ ]
airscrew revs : 1400 [r.p.m.]
pitch at Max speed 1.68 [m]
blade-tip speed at Vmax and max revs. : 232 [m/s]
calculation : *1* (dimensions)
mean wing chord : 2.00 [m]
calculated wing chord (rounded tips): 2.13 [m]
wing aspect ratio : 11.83 []
gap : 2.17 [m]
gap/chord : 1.08 [ ]
seize (span*length*height) : 1128 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 8.5 [kg/hr]
fuel consumption(cruise speed) : 78.8 [kg/hr] (107.5 [litre/hr]) at 58 [%] power
distance flown for 1 kg fuel : 1.61 [km/kg]
estimated total fuel capacity : 732 [litre] (537 [kg])
calculation : *3* (weight)
weight engine(s) dry : 850.0 [kg] = 2.29 [kg/KW]
weight 78 litre oil tank : 6.6 [kg]
oil tank filled with 2.8 litre oil : 2.5 [kg]
oil in engine 21 litre oil : 18.5 [kg]
fuel in engine 3 litre fuel : 1.9 [kg]
weight 46 litre gravity patrol tank(s) : 6.9 [kg]
weight radiator : 55.6 [kg]
weight exhaust pipes & fuel lines 21.8 [kg]
weight self-starter : 4.5 [kg]
weight cowling 7.4 [kg]
weight airscrew(s) (wood) incl. boss & bolts : 55.6 [kg]
total weight propulsion system : 1025 [kg](28.1 [%])
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fuselage skeleton (wood gauge : 9.41 [cm]): 276 [kg]
bracing : 25.5 [kg]
fuselage covering ( 28.1 [m2] doped linen fabric) : 9.0 [kg]
weight controls + indicators: 8.9 [kg]
weight seats : 9.0 [kg]
weight other details, lighting set, etc. : 9.1 [kg]
In the G. IV was behind the pilot the bomb hold, if necessary the tail gunner could come to the pilot. In the G. V, this was no longer possible because the main fuel tank was installed directly behind the pilot.
weight bomb storage : 35.0 [kg]
weight Görz bomb sight with 90 cm Zeiss-telescope: 2.5 [kg]
weight oxygen/compressed air flasks for high altitude : 19.5 [kg]
weight interior + equipment + fuel lines: 58 [kg]
total weight fuselage : 453 [kg](12.4 [%])
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weight wing covering (doped linen fabric) : 61 [kg]
total weight ribs (149 ribs) : 217 [kg]
weight engine mounts : 19 [kg]
weight two 343 [litre] main fuel tanks empty : 54.9 [kg]
load on front upper spar (clmax) per running metre : 735.9 [N]
load on rear upper spar (vmax) per running metre : 411.9 [N]
total weight 8 spars : 144 [kg]
weight wings : 422 [kg]
weight wing/square meter : 4.44 [kg]
weight 16 interplane struts & cabane : 89.5 [kg]
weight cables (160 [m]) : 36.2 [kg] (= 227 [gram] per metre)
diameter cable : 6.1 [mm]
weight fin & rudder (6.5 [m2]) : 29.9 [kg]
weight stabilizer & elevator (10.7 [m2]): 48.1 [kg]
total weight wing surfaces & bracing : 699 [kg] (19.2 [%])
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weight machine-gun(s) : 28.5 [kg]
weight pivot mounting mg :13.8 [kg]
weight armament : 42 [kg]
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wheel pressure : 912.0 [kg]
weight 4 wheels (810 [mm] by 150 [mm]) : 90.5 [kg]
weight tailskid : 5.6 [kg]
weight undercarriage with axle 65.7 [kg]
total weight landing gear : 161.9 [kg] (4.4 [%]
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calculated empty weight : 2381 [kg](65.3 [%])
weight oil for 7.2 hours flying : 61.4 [kg]
weight cooling fluids : 80.1 [kg]
weight 3 drums empty : 6.8 [kg]
weight ammunition (1500 rounds) : 49.1 [kg]
weight signal pistol with cartridges : 3.6 [kg]
weight automatic pistol with spare magazines : 1.2 [kg]
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calculated operational weight empty : 2576 [kg] (70.6 [%])
published operational weight empty : 2413 [kg] (66.1 [%])
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weight crew : 243 [kg]
weight (electrical heated) clothing for high altitude : 18.0 [kg]
weight fuel for 2.0 hours flying : 158 [kg]
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operational weight : 2995 [kg](82.1 [%])
bomb load : 500 [kg]
operational weight bombing mission : 3495 [kg]
fuel reserve : 153 [kg] enough for 1.95 [hours] flying
operational weight fully loaded : 3648 [kg] with fuel tank filled for 58 [%]
published maximum take-off weight : 3648 [kg] (100.0 [%])
calculation : * 4 * (engine power)
power loading (Take-off) : 9.84 [kg/kW]
total power : 370.7 [kW] at 1400 [r.p.m]
calculation : *5* (loads)
manoeuvre load : 1.5 [g] at 1000 [m]
limit load : 2.5 [g] ultimate load : 3.8 [g] load factor : 1.3 [g]
design flight time : 4.20 [hours]
design cycles : 238 sorties, design hours : 1000 [hours]
wing loading (MTOW) : 377 [N/m^2]
wing stress (3 g) during operation : 244 [N/kg] at 3g emergency manoeuvre
calculation : *6* (angles of attack)
angle of attack zero lift : -1.08 ["]
max. angle of attack (stalling angle) : 10.60 ["]
angle of attack at max. speed : 4.04 ["]
calculation : *7* (lift & drag ratios
lift coefficient at angle of attack 0° :0.10 [ ]
lift coefficient at max. angle of attack : 1.08 [ ]
lift coefficient at max. speed : 0.47 [ ]
induced drag coefficient at max. speed : 0.0108 [ ]
drag coefficient at max. speed : 0.0626 [ ]
drag coefficient (zero lift) : 0.0518 [ ]
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 : 103 [km/hr] at 3658 [m] (power:38 [%])
min. power speed (max range) : 103 [km/hr] at 3658 [m] (power:38 [%])
max. rate of climb speed : 88.5 [km/hr] at sea-level
cruising speed : 127 [km/hr] op 3658 [m] (power:51 [%])
design speed prop : 134 [km/hr]
maximum speed : 141 [km/hr] op 3658 [m] (power:65 [%])
climbing speed at sea-level (without bombload) : 276 [m/min]
calculation : *9* (regarding various performances)
take-off distance at sea-level : 150 [m]
lift/drag ratio : 10.04 [ ]
max. practical ceiling : 6575 [m] with flying weight :2643 [kg]
practical ceiling (operational weight): 5875 [m] with flying weight :2995 [kg]
practical ceiling fully loaded (mtow- 1 hour fuel) : 4800 [m] with flying weight :3569 [kg]
published ceiling (5500 [m]
climb to 1500m (without bombload) : 5.60 [min]
climb to 3000m (without bombload) : 13.05 [min]
max. dive speed : 418.6 [km/hr] at 3800 [m] height
load factor at max. angle turn 2.02 ["g"]
turn radius at 500m: 67 [m]
time needed for 360* turn 12.4 [seconds] at 500m
calculation *10* (action radius & endurance)
operational endurance : 4.17 [hours] with 3 crew and 500 [kg] bombload and 61.3 [%] fuel
published endurance : 6.00 [hours] with 3 crew and possible useful (bomb) load : 356 [kg] and 88.1 [%] fuel
action radius : 651 [km] with 3 crew and 20[kg] photo camera/radio transmitter or bombload
max range theoretically with additional fuel tanks for total 1425 [litre] fuel : 1683 [km]
useful load with action-radius 250km : 518 [kg]
production : 65.79 [tonkm/hour]
oil and fuel consumption per tonkm : 1.33 [kg]
Literature :
Praktisch handboek vliegtuigen deel 1 page 271
Wikipedia
Warplanes WOI page 62,72,76,131
Jane’s fighting aircraft WWI page 156,157tf
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
Crash Paderborn 19 September 1917
(c) B van der Zalm 23 September 2019 contact : info.aircraftinvestigation@gmail.com python 3.7.4