AIRCRAFT INVESTIGATION
weight and performance calculations for the WWI light bomber Airco D.H.9A
Airco D.H.9A
role : light bomber
importance : ***
first flight : operational : August 1918
country : United-Kingdom
design :
production : 2500 aircraft
general information :
The reliable 400 hp Liberty engine gave the D.H.9A excellent performance. But it arrived too late at the front to play a significant role. It was used after the war for a long period. It could carry two 104 kg bombs with 164 km/hr at 5100m cruising height m. First squadron deliveries of DH9A’s were made in June 1918 to no.110 sq., although they did not become operational in France until the end of August. This squadron made raids in September and October against German cities. 3 other squadrons received the DH9A , but two of these only received the aircraft in November and hence the type saw little combat service in WW1. The type remained in widespread production after the war and nearly 2500 aircraft were built ! It was in service with the RAF till 1931.
Gap : 1.67 m chord : 1.75m total area of tail (empennage) : 7.44 m2, area of elevators : 1.11 m2, area of rudder : 1.27 m2 area of fin : 0.50 m2 airscrew diam. 3.05 m pitch :
3.75 m tank capacity : 112 gallon = 509 litre
users : RAF
crew : 2
armament : 1 synchronized 7.70 [mm] (0.303 in) Vickers Mk.II machine-gun
and 2 movable 7.70 [mm] (0.303 in) Lewis MK.III machine-guns
engine : 1 Liberty L-12 liquid-cooled 12 -cylinder V-engine 400 [hp](294.2 KW)
dimensions :
wingspan : 14.01 [m], length : 9.22 [m], height : 3.45[m]
wing area : 45.22 [m^2]
weights :
max.take-off weight : 2107 [kg]
empty weight operational : 1272 [kg] bombload : 210 [kg]
performance :
maximum speed : 198 [km/hr] at sea-level
climbing speed : 194 [m/min]
service ceiling : 5105 [m]
endurance : 5.12 [hours]
estimated action radius : 456 [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 :0.67 [ ]
diameter airscrew 3.05 [m]
angle of attack prop : 14.70 [ ]
fine pitch
reduction : 1.00 [ ]
airscrew revs : 1750 [r.p.m.]
pitch at Max speed 1.89 [m]
blade-tip speed at Vmax and max revs. : 285 [m/s]
calculation : *1* (dimensions)
mean wing chord : 1.61 [m]
calculated wing chord (rounded tips): 1.76 [m]
wing aspect ratio : 8.68 []
gap : 1.67 [m]
gap/chord : 1.03 [ ]
seize (span*length*height) : 446 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 4.1 [kg/hr]
fuel consumption(cruise speed) : 64.2 [kg/hr] (87.6 [litre/hr]) at 62 [%] power
distance flown for 1 kg fuel : 2.78 [km/kg]
estimated total fuel capacity : 509 [litre] (373 [kg])
calculation : *3* (weight)
weight engine(s) dry : 383.0 [kg] = 1.30 [kg/KW]
weight 36 litre oil tank : 3.0 [kg]
oil tank filled with 2.2 litre oil : 2.0 [kg]
oil in engine 16 litre oil : 14.7 [kg]
fuel in engine 2 litre fuel : 1.5 [kg]
weight 37 litre gravity patrol tank(s) : 5.6 [kg]
weight radiator : 47.1 [kg]
weight exhaust pipes & fuel lines 35.2 [kg]
weight self-starter : 7.2 [kg]
weight cowling 11.8 [kg]
weight airscrew(s) (wood) incl. boss & bolts : 44.1 [kg]
total weight propulsion system : 552 [kg](26.2 [%])
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fuselage skeleton (wood gauge : 6.78 [cm]): 109 [kg]
bracing : 7.1 [kg]
fuselage covering ( 16.1 [m2] doped linen fabric) : 5.1 [kg]
weight controls + indicators: 6.8 [kg]
weight seats : 6.0 [kg]
weight other details, lighting set, etc. : 5.1 [kg]
weight bomb storage : 14.7 [kg]
weight Course Setting Bomb Sight (Wimperis) : 1.5 [kg]
weight 472 [litre] main fuel tank empty : 37.7 [kg]
weight oxygen/compressed air flasks for high altitude : 11.1 [kg]
weight engine mounts & firewalls : 15 [kg]
total weight fuselage : 218 [kg](10.4 [%])
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weight wing covering (doped linen fabric) : 29 [kg]
total weight ribs (107 ribs) : 125 [kg]
load on front upper spar (clmax) per running metre : 642.1 [N]
load on rear upper spar (vmax) per running metre : 429.1 [N]
total weight 8 spars : 72 [kg]
weight wings : 226 [kg]
weight wing/square meter : 5.01 [kg]
weight 8 interplane struts & cabane : 21.9 [kg]
weight cables (79 [m]) : 8.9 [kg] (= 114 [gram] per metre)
diameter cable : 4.3 [mm]
weight fin & rudder (2.3 [m2]) : 11.7 [kg]
weight stabilizer & elevator (5.1 [m2]): 25.8 [kg]
total weight wing surfaces & bracing : 295 [kg] (14.0 [%])
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weight machine-gun(s) : 42.0 [kg]
weight Scarff ring mounting mg :6.9 [kg]
weight ammunition magazine(s) :2.6 [kg]
weight C.C.(Constantinesco-Colley)hydraulic synchronization gear : 1.0 [kg]
weight Aldis gunsight : 0.8 [kg]
weight armament : 53 [kg]
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wheel pressure : 1053.5 [kg]
weight 2 wheels (850 [mm] by 131 [mm]) : 42.6 [kg]
weight tailskid : 5.0 [kg]
weight undercarriage with axle 31.3 [kg]
total weight landing gear : 78.9 [kg] (3.7 [%]
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Russian copy of the DH9A, 2400 were built in the USSR as Polikarpov R-1
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calculated empty weight : 1198 [kg](56.8 [%])
weight oil for 6.1 hours flying : 25.3 [kg]
weight cooling fluids : 63.5 [kg]
weight 5 drums empty : 2.1 [kg]
weight ammunition (1235 rounds) : 36.0 [kg]
weight Very pistol with cartridges : 3.6 [kg]
weight automatic pistol with spare magazines : 1.2 [kg]
*******************************************************************
calculated operational weight empty : 1327 [kg] (63.0 [%])
published operational weight empty : 1272 [kg] (60.4 [%])
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weight crew : 162 [kg]
weight (electrical heated) clothing for high altitude : 12.0 [kg]
weight fuel for 2.0 hours flying : 128 [kg]
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operational weight : 1630 [kg](77.3 [%])
bomb load : 210 [kg]
operational weight bombing mission : 1840 [kg]
fuel reserve : 245 [kg] enough for 3.81 [hours] flying
possible additional useful load : 23 [kg]
operational weight fully loaded : 2107 [kg] with fuel tank filled for 100 [%]
published maximum take-off weight : 2107 [kg] (100.0 [%])
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calculation : * 4 * (engine power)
power loading (Take-off) : 7.16 [kg/kW]
total power : 294.2 [kW] at 1750 [r.p.m]
calculation : *5* (loads)
manoeuvre load : 3.1 [g] at 1000 [m]
limit load : 3.0 [g] ultimate load : 4.5 [g] load factor : 1.1 [g]
design flight time : 3.58 [hours]
design cycles : 126 sorties, design hours : 450 [hours]
wing loading (MTOW) : 457 [N/m^2]
wing stress (3 g) during operation : 239 [N/kg] at 3g emergency manoeuvre
calculation : *6* (angles of attack)
angle of attack zero lift : -1.38 ["]
max. angle of attack (stalling angle) : 11.72 ["]
angle of attack at max. speed : 0.83 ["]
calculation : *7* (lift & drag ratios
lift coefficient at angle of attack 0° :0.12 [ ]
lift coefficient at max. angle of attack : 1.14 [ ]
lift coefficient at max. speed : 0.19 [ ]
induced drag coefficient at max. speed : 0.0024 [ ]
drag coefficient at max. speed : 0.0426 [ ]
drag coefficient (zero lift) : 0.0402 [ ]
calculation : *8* (speeds
stalling speed at sea-level (OW): 81 [km/u]
landing speed at sea-level (OW without bombload): 97 [km/hr]
min. drag speed (max endurance) : 111 [km/hr] at 2552 [m](power :31 [%])
min. power speed (max range) : 123 [km/hr] at 2552 [m] (power:33 [%])
max. rate of climb speed : 116.2 [km/hr] at sea-level
cruising speed : 178 [km/hr] op 2552 [m] (power:61 [%])
design speed prop : 188 [km/hr]
maximum speed : 198 [km/hr] op 100 [m] (power:99 [%])
climbing speed at sea-level (without bombload) : 423 [m/min]
calculation : *9* (regarding various performances)
take-off distance at sea-level : 138 [m]
lift/drag ratio : 9.77 [ ]
max. practical ceiling : 6575 [m] with flying weight :1399 [kg]
practical ceiling (operational weight): 5875 [m] with flying weight :1630 [kg]
practical ceiling fully loaded (mtow- 1 hour fuel) : 4725 [m] with flying weight :2043 [kg]
published ceiling (5105 [m]
climb to 1500m (without bombload) : 3.92 [min]
climb to 3000m (without bombload) : 9.41 [min]
max. dive speed : 447.8 [km/hr] at 3725 [m] height
load factor at max. angle turn 2.31 ["g"]
turn radius at 500m: 68 [m]
time needed for 360* turn 11.5 [seconds] at 500m
calculation *10* (action radius & endurance)
operational endurance : 5.81 [hours] with 2 crew and 245 [kg] bombload and 100.0 [%] fuel
published endurance : 5.12 [hours] with 2 crew and possible useful (bomb) load : 289 [kg] and 88.1 [%] fuel
action radius : 830 [km] with 2 crew and 20[kg] photo camera/radio transmitter or bombload
max range theoretically with additional fuel tanks for total 1009 [litre] fuel : 2054 [km]
useful load with action-radius 250km : 438 [kg]
production : 78.00 [tonkm/hour]
oil and fuel consumption per tonkm : 0.88 [kg]
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Literature :
Bombers 1914-19 page 63,142
Praktisch handboek vleigtuigen deel 1 page205
Warplanes WWI page 136
Jane’s Fighting Aircraft WWI page 44fd
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