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weight and performance calculations for the Airco D.H.6 primary trainer WWI biplane
Airco D.H.6
role : primary trainer
importance : ***
first flight : operational : February 1917
country : United-Kingdom
design : Geoffrey de Havilland
production : 2280 aircraft
nicknames : “Clutching hand” and “skyhook”
general information :
Inexpensive and easy to built, easy to repair > top & bottom wings were interchangeable. The RAF 1a engine was familiar to the mechanics. It had easy flying characteristics but was deliberately unstable for better training.
It was described as “too safe” to make a good trainer. It was extensively used in 1917 till the arrival of the Avro 504K at the end of 1917. 300 surplus DH6 were then transferred to the RNAS and used for ASW duties. It only advantage in this role was that it proved surprisingly “seaworthy” because it could float for 10 hours after ditching !
Gap : 1.74m chord : 1.93 m prop diam : 2.77m pitch : 3.05 fuel : 118 litre
Total area of tail (empennage) : 7.52 m2 area of elevators : 1.21m each, area of rudder : 1.11 m2 area of fin : 0.51 m2 landing speed : 63 km/u
users : RFC
crew : 2
armament : no fixed armament
engine : 1 RAF 1a air-cooled 8 -cylinder V-engine 90 [hp](66.2 KW)
dimensions :
wingspan : 10.95 [m], length : 8.32 [m], height : 3.29[m]
wing area : 40.53 [m^2]
weights :
max.take-off weight : 923 [kg]
empty weight operational : 664 [kg] bombload : 50 [kg]
performance :
maximum speed : 113 [km/hr] at sea-level
climbing speed : 66 [m/min]
service ceiling : 1859 [m]
endurance : 3.21 [hours]
estimated action radius : 163 [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 4 -bladed tractor airscrew with max. efficiency :0.60 [ ]
diameter airscrew 2.77 [m]
angle of attack prop : 19.84 [ ]
reduction : 0.50 [ ]
airscrew revs : 800 [r.p.m.]
pitch at Max speed 2.35 [m]
blade-tip speed at Vmax and max revs. : 120 [m/s]
calculation : *1* (dimensions)
mean wing chord : 1.85 [m]
calculated wing chord (rounded tips): 2.09 [m]
wing aspect ratio : 5.92 []
gap : 1.74 [m]
gap/chord : 0.94 [ ]
seize (span*length*height) : 300 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 1.5 [kg/hr]
fuel consumption(cruise speed) : 23.7 [kg/hr] (32.3 [litre/hr]) at 79 [%] power
distance flown for 1 kg fuel : 4.29 [km/kg]
estimated total fuel capacity : 118 [litre] (86 [kg])
Airco DH6 with mechanic at Point Cook, c.1918
calculation : *3* (weight)
weight engine(s) dry : 204.0 [kg] = 3.08 [kg/KW]
weight reduction gear : 2.6 [kg]
weight 8 litre oil tank : 0.7 [kg]
oil tank filled with 0.5 litre oil : 0.4 [kg]
oil in engine 0 litre oil : 0.3 [kg]
fuel in engine 0 litre fuel : 0.3 [kg]
weight 14 litre gravity patrol tank(s) : 2.1 [kg]
weight cowling 2.6 [kg]
weight airscrew(s) (wood) incl. boss & bolts : 23.2 [kg]
total weight propulsion system : 238 [kg](25.8 [%])
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fuselage skeleton (wood gauge : 7.69 [cm]): 126 [kg]
bracing : 7.4 [kg]
fuselage covering ( 13.1 [m2] doped linen fabric) : 4.2 [kg]
weight dual controls + indicators: 13.1 [kg]
weight seats : 6.0 [kg]
weight other details, lighting set, etc. : 5.1 [kg]
weight bomb storage : 3.5 [kg]
weight 104 [litre] main fuel tank empty : 8.3 [kg]
weight engine mounts & firewalls : 3 [kg]
total weight fuselage : 177 [kg](19.2 [%])
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weight wing covering (doped linen fabric) : 26 [kg]
total weight ribs (41 ribs) : 55 [kg]
load on front upper spar (clmax) per running metre : 786.6 [N]
load on rear upper spar (vmax) per running metre : 215.1 [N]
total weight 8 spars : 54 [kg]
weight wings : 135 [kg]
weight wing/square meter : 3.33 [kg]
weight 8 interplane struts & cabane : 24.3 [kg]
weight cables (70 [m]) : 5.9 [kg] (= 85 [gram] per metre)
diameter cable : 3.7 [mm]
weight fin & rudder (1.4 [m2]) : 4.8 [kg]
weight stabilizer & elevator (4.6 [m2]): 15.5 [kg]
total weight wing surfaces & bracing : 185 [kg] (20.1 [%])
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weight armament : 0 [kg]
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wheel pressure : 461.5 [kg]
weight 2 wheels (790 [mm] by 99 [mm]) : 23.1 [kg]
weight tailskid : 3.5 [kg]
weight undercarriage with axle 33.4 [kg]
total weight landing gear : 59.9 [kg] (6.5 [%]
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calculated empty weight : 660 [kg](71.5 [%])
weight oil for 3.9 hours flying : 5.9 [kg]
*******************************************************************
calculated operational weight empty : 666 [kg] (72.2 [%])
published operational weight empty : 664 [kg] (71.9 [%])
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weight crew : 162 [kg]
weight fuel for 2.0 hours flying : 47 [kg]
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operational weight : 876 [kg](94.9 [%])
bombload could not be carried with fuel for 2 hours flying time
fuel reserve : 39 [kg] enough for 1.64 [hours] flying
possible additional useful load : 9 [kg]
operational weight fully loaded : 923 [kg] with fuel tank filled for 100 [%]
published maximum take-off weight : 923 [kg] (100.0 [%])
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calculation : * 4 * (engine power)
power loading (operational without bombload) : 13.23 [kg/kW]
total power : 66.2 [kW] at 1600 [r.p.m]
calculation : *5* (loads)
manoeuvre load : 1.8 [g] at 1000 [m]
limit load : 3.75 [g] ultimate load : 5.6 [g] load factor : 2.7 [g]
design flight time : 1.28 [hours]
design cycles : 802 sorties, design hours : 1030 [hours]
operational wing loading : 212 [N/m^2]
wing stress (3 g) during operation : 191 [N/kg] at 3g emergency manoeuvre
calculation : *6* (angles of attack)
angle of attack zero lift : -1.52 ["]
max. angle of attack (stalling angle) : 12.81 ["]
angle of attack at max. speed : 2.98 ["]
calculation : *7* (lift & drag ratios
lift coefficient at angle of attack 0° :0.12 [ ]
lift coefficient at max. angle of attack : 1.13 [ ]
lift coefficient at max. speed : 0.35 [ ]
induced drag coefficient at max. speed : 0.0120 [ ]
drag coefficient at max. speed : 0.0514 [ ]
drag coefficient (zero lift) : 0.0394 [ ]
calculation : *8* (speeds
stalling speed at sea-level (OW): 63 [km/u]
landing speed at sea-level (OW without bombload): 76 [km/hr]
min. drag speed (max endurance) : 87 [km/hr] at 930 [m](power :67 [%])
min. power speed (max range) : 94 [km/hr] at 930 [m] (power:71 [%])
max. rate of climb speed : 77.4 [km/hr] at sea-level
cruising speed : 102 [km/hr] op 930 [m] (power:79 [%])
design speed prop : 107 [km/hr]
maximum speed : 113 [km/hr] op 100 [m] (power:99 [%])
climbing speed at sea-level (without bombload) : 96 [m/min]
calculation : *9* (regarding various performances)
take-off distance at sea-level : 175 [m]
lift/drag ratio : 8.14 [ ]
max. practical ceiling : 2750 [m] with flying weight :759 [kg]
practical ceiling (operational weight): 1800 [m] with flying weight :876 [kg]
practical ceiling fully loaded (mtow- 1 hour fuel) : 1625 [m] with flying weight :899 [kg]
published ceiling (1859 [m]
climb to 1500m (without bombload) : 20.17 [min]
max. dive speed : 264.5 [km/hr] at 625 [m] height
load factor at max. angle turn 1.33 ["g"]
turn radius at 500m: 50 [m]
time needed for 360* turn 15.2 [seconds] at 500m
calculation *10* (action radius & endurance)
operational endurance : 3.16 [hours] with 2 crew and 20 [kg] useful load and 86.7 [%] fuel
published endurance : 3.21 [hours] with 2 crew and possible useful (bomb) load : 19 [kg] and 88.1 [%] fuel
action radius : 161 [km] with 2 crew and 20[kg] photo camera/radio transmitter or bombload
max range theoretically with additional fuel tanks for total 240 [litre] fuel : 755 [km]
useful load with action-radius 250km : 59 [kg]
production : 6.04 [tonkm/hour]
oil and fuel consumption per tonkm : 4.17 [kg]
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Literature :
Praktisch handbook vliegtuigen deel 1 page 213
Jane’s FAWOI page 42df
Fighters 1914-19 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. 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