Airco D.H.4 (250 hp)
role : light bomber
first flight : august 1916 at Hendon operational : March 1917
country : United-Kingdom
design : Geoffrey de Havilland
production : all D.H.4 versions : 6295 aircraft (4846 built in the USA DH-4A “Liberty plane”, 1449 in the UK)
general information :
The D.H.4 is seen as the best light bomber W
OI. The DH.4 entered service on 6 March 1917 with No. 55 Squadron in France. It was designed from the outset for high-speed day bombing. It was easy to fly. The only drawback was the separation of the two cockpits by the main fuel tank, hampering communication. Communication between pilot and gunner was possible through a speaking tube between the cockpits. It out-performed many contemporary single-seaters. The prototype flew for the first time august 1916, powered by the new BHP 220 hp engine. It could fly 175 km/u at 3048m with bombload. Production D.H.4 switched to the excellent 250 hp Rolls Royce Eagle III engine.
Extensive use is made of three-ply wood in the fuselage. From the nose to aft of the observer seat the fuselage is devoid of wire bracing, the plywood serving the purpose.
On 24 Dec 1917 D.H.4’s carried out a raid on Mannheim, operating from Ochey, distance 215 km. For this distance 100 kg’s of bombs could be carried.
Gap = 1,67 m chord: 1.67 m total area of tail (empennage) : 7.53 m2, area of elevators : 1.11m2 area of rudder : 1.27 m2 area of fin 0.50 m2 aircrew diam : 2.67 m pitch : 2.5 m revs with 240 BHP engine : 1355 rpm tank capacity : 66 gallon = 300 litre. Oil : 21 litre landing speed : 84 km/u
speed : 193 km/u at SL (176 KW/240 hp engine)
187 km/u at 1981m (184 KW/250 hp engine)
Time to height (176 KW/240 hp BHP motor )
8.00 min. naar 1976m
14.10 min. naar 3040m
29.15 min. naar 4560m
The DH4 had complete dual control. The control lever for the observer was removable. In the observer cockpit there was also a speed indicator, a throttle and a switch for night illumination.
The pilot could release the bombs with a Bowden cable. For aiming the pilot could us a Negative lens bomb sight.
users : RFC
crew : 2
armament : 1 Constantinesco synchronized 7.70 [mm] (0.303 in) Vickers machine-gun
and 1 movable 7.70 [mm] (0.303 in) Lewis machine-gun for the observer
engine : 1 Rolls Royce Eagle III liquid-cooled 12 -cylinder V-engine 250 [hp](183.9 KW)
dimensions :
wingspan : 12.93 [m], length : 9.04 [m], height : 3.55[m]
wing area : 40.32 [m^2]
weights :
max.take-off weight : 1542 [kg]
empty weight operational : 1044 [kg] bombload : 208 [kg]
performance :
maximum speed : 191 [km/u] op 1000 [m]
climbing speed : 248 [m/min]
service ceiling : 4877 [m]
endurance : 4.23 [hours]
estimated action radius : 364 [km]
description :
2-bay biplane with fixed landing gear and tail strut
two spar upper and lower wing
engine, landing gear and fuel in or attached to fuselage, bombs attached to the wing
airscrew :
fixed pitch 2 -bladed tractor airscrew with max. efficiency :0.67 [ ]
diameter airscrew 2.67 [m]
angle of attack prop : 17.55 [ ]
reduction : 1.00 [ ]
airscrew revs : 1600 [r.p.m.]
pitch at Max speed 1.99 [m]
blade-tip speed at Vmax and max revs. : 230 [m/s]
calculation : *1* (dimensions)
mean wing chord : 1.56 [m]
calculated wing chord (rounded tips): 1.71 [m]
wing aspect ratio : 8.29 []
gap : 1.67 [m]
gap/chord : 1.07 [ ]
seize (span*length*height) : 415 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 2.8 [kg/hr]
fuel consumption(cruise speed) : 45.8 [kg/hr] (62.5 [litre/hr]) at 62 [%] power
distance flown for 1 kg fuel : 3.75 [km/kg]
estimated total fuel capacity : 300 [litre] (220 [kg])
calculation : *3* (weight)
weight engine(s) dry : 379.0 [kg] = 2.06 [kg/KW]
weight 20 litre oil tank : 1.7 [kg]
oil tank filled with 1.4 litre oil : 1.2 [kg]
oil in engine 10 litre oil : 9.2 [kg]
fuel in engine 1 litre fuel : 0.9 [kg]
weight 27 litre gravity patrol tank(s) : 4.0 [kg]
weight radiator : 29.4 [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 : 27.6 [kg]
total weight propulsion system : 485 [kg](31.5 [%])
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fuselage skeleton (wood gauge : 6.53 [cm]): 99 [kg]
bracing : 6.3 [kg]
fuselage covering ( 15.4 [m2] doped linen fabric) : 4.9 [kg]
weight controls + indicators: 6.6 [kg]
weight seats : 6.0 [kg]
weight other details, lighting set, etc. : 5.1 [kg]
weight bomb storage : 14.6 [kg]
weight 273 [litre] main fuel tank empty : 21.9 [kg]
weight oxygen/compressed air flasks for high altitude : 9.2 [kg]
weight engine mounts & firewalls : 9 [kg]
total weight fuselage : 182 [kg](11.8 [%])
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weight wing covering (doped linen fabric) : 26 [kg]
total weight ribs (81 ribs) : 92 [kg]
load on front upper spar (clmax) per running metre : 638.6 [N]
load on rear upper spar (vmax) per running metre : 337.3 [N]
total weight 8 spars : 49 [kg]
weight wings : 167 [kg]
weight wing/square meter : 4.13 [kg]
weight 8 interplane struts & cabane : 21.0 [kg]
weight cables (75 [m]) : 6.6 [kg] (= 89 [gram] per metre)
diameter cable : 3.8 [mm]
weight fin & rudder (1.9 [m2]) : 8.3 [kg]
weight stabilizer & elevator (4.5 [m2]): 19.0 [kg]
total weight wing surfaces & bracing : 222 [kg] (14.4 [%])
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weight machine-gun(s) : 28.9 [kg]
weight Scarff ring mounting mg :5.0 [kg]
weight ammunition magazine(s) :2.0 [kg]
weight synchronizing system : 1.0 [kg]
weight armament : 37 [kg]
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Can only operate from paved runways
wheel pressure : 771.0 [kg]
weight 2 wheels (720 [mm] by 80 [mm]) : 23.9 [kg]
weight tailskid : 2.5 [kg]
weight undercarriage with axle 38.9 [kg]
total weight landing gear : 65.4 [kg] (4.2 [%]
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Production of the D.H.4 was on a large scale and Rolls Royce could not keep up with the production of the RR Eagle engine, so also alternative engines were installed such as the 200hp Puma/Adriatic/(BHP), 200 hp RAF 3a, 260 hp FIAT A-12
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calculated empty weight : 982 [kg](63.7 [%])
weight oil for 5.1 hours flying : 14.0 [kg]
weight cooling fluids : 39.7 [kg]
weight 6 drums empty : 2.5 [kg]
weight ammunition (1164 rounds) : 42.1 [kg]
weight Very pistol with cartridges : 3.6 [kg]
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calculated operational weight empty : 1081 [kg] (70.1 [%])
published operational weight empty : 1044 [kg] (67.7 [%])
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weight crew : 162 [kg]
weight fuel for 2.0 hours flying : 92 [kg]
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operational weight : 1335 [kg](86.6 [%])
bombload could not be carried with fuel for 2 hours flying time
fuel reserve : 128 [kg] enough for 2.80 [hours] flying
possible additional useful load : 79 [kg]
operational weight fully loaded : 1542 [kg] with fuel tank filled for 100 [%]
published maximum take-off weight : 1542 [kg] (100.0 [%])
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calculation : * 4 * (engine power)
power loading (Take-off) : 8.39 [kg/kW]
total power : 183.9 [kW] at 1600 [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 : 1.4 [g]
design flight time : 3.38 [hours]
design cycles : 207 sorties, design hours : 700 [hours]
wing loading (MTOW) : 375 [N/m^2]
wing stress (3 g) during operation : 272 [N/kg] at 3g emergency manoeuvre
calculation : *6* (angles of attack)
angle of attack zero lift : -1.39 ["]
max. angle of attack (stalling angle) : 11.88 ["]
angle of attack at max. speed : 1.01 ["]
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 : 0.21 [ ]
induced drag coefficient at max. speed : 0.0029 [ ]
drag coefficient at max. speed : 0.0317 [ ]
drag coefficient (zero lift) : 0.0287 [ ]
calculation : *8* (speeds
stalling speed at sea-level (OW): 77 [km/u]
landing speed at sea-level (OW without bombload): 93 [km/hr]
min. drag speed (max endurance) : 116 [km/hr] at 2438 [m](power :35 [%])
min. power speed (max range) : 124 [km/hr] at 2438 [m] (power:37 [%])
max. rate of climb speed : 116.0 [km/hr] at sea-level
cruising speed : 172 [km/hr] op 2438 [m] (power:60 [%])
design speed prop : 181 [km/hr]
maximum speed : 191 [km/hr] op 1000 [m] (power:87 [%])
climbing speed at sea-level (without bombload) : 313 [m/min]
Note the upward bent exhaust pipe of the 250 hp RR Eagle III engine
calculation : *9* (regarding various performances)
take-off distance at sea-level : 173 [m]
lift/drag ratio : 11.29 [ ]
max. practical ceiling : 5725 [m] with flying weight :1140 [kg]
practical ceiling (operational weight): 5000 [m] with flying weight :1335 [kg]
practical ceiling fully loaded (mtow- 1 hour fuel) : 4425 [m] with flying weight :1496 [kg]
published ceiling (4877 [m]
climb to 1500m (without bombload) : 5.37 [min]
climb to 3000m (without bombload) : 13.31 [min]
max. dive speed : 504.8 [km/hr] at 3425 [m] height
load factor at max. angle turn 1.96 ["g"]
turn radius at 500m: 67 [m]
time needed for 360* turn 12.6 [seconds] at 500m
calculation *10* (action radius & endurance)
operational endurance : 1.98 [hours] with 2 crew and 208 [kg] bombload and 41.2 [%] fuel
published endurance : 4.23 [hours] with 2 crew and possible useful (bomb) load : 105 [kg] and 88.1 [%] fuel
action radius : 523 [km] with 2 crew and 20[kg] photo camera/radio transmitter or bombload
max range theoretically with additional fuel tanks for total 580 [litre] fuel : 1596 [km]
useful load with action-radius 250km : 165 [kg]
production : 28.42 [tonkm/hour]
oil and fuel consumption per tonkm : 1.71 [kg]
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I_°°=/
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Lt. Chambers of no.49 sq. besides his D.H.4
Literature :
Warplanes WOI page 62,96,102dt,103,112 ,132
Bombers 1914-19 page 62,139,140
Praktisch handboek vliegtuigen deel 1 page 200
Jane’s FAWOI page 40,41dft
Armament of British Aircraft 1909-1939 page 124 -128
Bomber 1914-1939 page 29
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.
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(c) B van der Zalm 04 January 2019 contact : info.aircraftinvestigation@gmail.com python 3.7.4