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weight and performance calculations for the De Havilland D.H.18A
De Havilland D.H.18A
role : light passenger aircraft
importance : ***
first flight : 08 April 1920 operational : August 1920
country : United-Kingdom
design : Geoffrey de Havilland
production : 6 aircraft
general information :
The first aircraft designed by Airco for civil use as passenger airplane. The prototype was delivered to AT&T for use on the route Croydon, London – Le Bourget, Paris, but it was wrecked in a forced landing shortly after take-off from Croydon on 16 August 1920.
Airco got bankrupt after which Geoffrey de Havilland, the chief designer , set up the De Havilland Aircraft Company, completing the two partly completed D.H.18 aircraft. The D.H.18’s continued to fly regular flights to the continent till 1923, when it was retired ,with G-EARO having flown 144834 km without accident.
registrations : D.H.18 prototype : G-EARI, D.H.18A : G-EARO, G-EAUF, G-EAWO, D.H.18B G-EAWW, G-EAWX
users : Aircraft Transport & Travel
crew : 1 passengers : 8
engine : 1 Napier Lion liquid-cooled 12 -cylinder W-engine 450 [hp](335.6 KW)
dimensions :
wingspan : 15.62 [m], length : 11.89 [m], height : 3.96[m]
wing area : 57.7 [m^2]
weights :
max.take-off weight : 2956 [kg]
empty weight operational : 1833 [kg] useful load : 700 [kg]
performance :
maximum speed :201 [km/u] op 1525 [m]
cruise speed :181 [km/u] op 1525 [m]
service ceiling : 4875 [m]
range : 832 [km]
description :
2-bay biplane with fixed landing gear and tail strut
two spar upper and lower wing
engines, landing gear attached to the fuselage, luggage compartment in the rear of the fuselage
The was efficient in operation with oil and fuel consumption per tonkm of only 0.51 [kg]
airscrew :
fixed pitch 2 -bladed tractor airscrew with max. efficiency :0.65 [ ]
estimated diameter airscrew 3.30 [m]
angle of attack prop : 20.49 [ ]
reduction : 0.66 [ ]
airscrew revs : 1384 [r.p.m.]
pitch at Max speed 2.42 [m]
blade-tip speed at Vmax and max revs. : 207 [m/s]
calculation : *1* (dimensions)
wing chord : 1.98 [m]
mean wing chord : 1.85 [m]
calculated wing chord (rounded tips): 2.02 [m]
wing aspect ratio : 8.46 []
gap : 2.08 [m]
gap/chord : 1.13 [ ]
seize (span*length*height) : 735 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 6.4 [kg/hr]
fuel consumption(cruise speed) : 68.7 [kg/hr] (93.7 [litre/hr]) at 67 [%] power
distance flown for 1 kg fuel : 2.63 [km/kg] at 2438 [m] cruise height, sfc : 307.9 [kg/kwh]
estimated total fuel capacity : 489.38 [litre] (358.71 [kg])
calculation : *3* (weight)
weight engine(s) dry : 435.0 [kg] = 1.30 [kg/KW]
weight reduction gear : 20.1 [kg]
weight 47.6 litre oil tank : 4.04 [kg]
oil tank filled with 2.5 litre oil : 2.3 [kg]
oil in engine 18.7 litre oil : 16.8 [kg]
fuel in engine 2.3 litre fuel : 1.68 [kg]
weight 39.9 litre gravity patrol tank(s) : 6.0 [kg]
weight radiator : 53.7 [kg]
weight exhaust pipes & fuel lines 40.8 [kg]
weight self-starter : 8.2 [kg]
weight cowling 13.4 [kg]
weight airscrew(s) (wood) incl. boss & bolts : 105.4 [kg]
total weight propulsion system : 724 [kg](24.5 [%])
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fuselage skeleton (wood gauge : 8.82 [cm]): 237 [kg]
fuselage width : 1.25 [m]
cabin layout : pitch : 87 [cm] (1+1) seating in 4.0 rows
pathway is very narrow > check !
passenger cabin area : 4.04 [m2]
weight 8.0 windows : 7.20 [kg]
passenger cabin width : 1.16 [m] cabin length : 3.48 [m] cabin height : 1.90 [m]
cabin space : 7.68 [m3]
weight cabin furbishing : 34.57 [kg]
length luggage compartment : 0.79 [m]
luggage compartment: 1.14 [m3]
enough space for 189 [kg] luggage/freight
normal weight luggage & freight 84 [kg] luggage/freight
suitable for light volumetric freight, not to much load near the tail for COG
bracing : 19.9 [kg]
fuselage covering ( 26.7 [m2] doped linen fabric) : 8.1 [kg]
weight instruments. : 2.5 [kg]
weight lighting : 1.1 [kg]
weight controls : 6.2 [kg]
weight seats : 45.0 [kg]
weight 450 [litre] main fuel tank empty : 36.0 [kg]
weight engine mounts & firewalls : 17 [kg]
total weight fuselage : 414 [kg](14.0 [%])
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weight wing covering (doped linen fabric) : 41 [kg]
total weight ribs (131 ribs) : 176 [kg]
load on front upper spar (clmax) per running metre : 968.7 [N]
load on rear upper spar (vmax) per running metre : 536.9 [N]
total weight 8 spars : 135 [kg]
weight wings : 352 [kg]
weight wing/square meter : 6.10 [kg]
weight 8 interplane struts & cabane : 54.9 [kg]
weight cables (91 [m]) : 19.4 [kg] (= 213 [gram] per metre)
diameter cable : 5.9 [mm]
weight fin & rudder (2.8 [m2]) : 17.7 [kg]
weight stabilizer & elevator (6.5 [m2]): 40.1 [kg]
total weight wing surfaces & bracing : 484 [kg] (16.4 [%])
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wheel pressure : 1478.0 [kg]
weight 2 wheels (980 [mm] by 151 [mm]) : 53.5 [kg]
weight tailskid : 8.5 [kg]
weight undercarriage with axle 74.9 [kg]
total weight landing gear : 136.8 [kg] (4.6 [%]
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calculated empty weight : 1759 [kg](59.5 [%])
weight oil for 5.5 hours flying : 35.2 [kg]
weight cooling fluids : 72.5 [kg]
calculated operational weight empty : 1866 [kg] (63.1 [%])
published operational weight empty : 1833 [kg] (62.0 [%])
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weight crew : 81 [kg]
weight fuel for 1.0 hours flying : 69 [kg]
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operational weight : 2016 [kg](68.2 [%])
fuel reserve : 290.0 [kg] enough for 4.22 [hours] flying
possible additional useful load : 650 [kg]
Gap : 6 ft 10 in = 2.08 m chord 6 ft 6 in = 1.98 m
operational weight fully loaded : 2956 [kg] with fuel tank filled for 100 [%]
published maximum take-off weight : 2956 [kg] (100.0 [%])
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calculation : * 4 * (engine power)
power loading (Take-off) : 8.81 [kg/kW]
power loading (operational without useful load) : 6.01 [kg/kW]
total power : 335.6 [kW] at 2100 [r.p.m]
calculation : *5* (loads)
manoeuvre load : 3.7 [g] at 1000 [m]
limit load : 3.0 [g] ultimate load : 4.5 [g] load factor : 1.4 [g]
design flight time : 3.22 [hours]
design cycles : 193 sorties, design hours : 620 [hours]
operational wing loading : 343 [N/m^2]
wing stress (3 g) during operation : 168 [N/kg] at 3g emergency manoeuvre
Interior of the D.H.18
calculation : *6* (angles of attack)
angle of attack zero lift : -1.38 ["]
max. angle of attack (stalling angle) : 11.81 ["]
angle of attack at max. speed : 1.02 ["]
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 : 0.21 [ ]
induced drag coefficient at max. speed : 0.0029 [ ]
drag coefficient at max. speed : 0.0339 [ ]
drag coefficient (zero lift) : 0.0310 [ ]
calculation : *8* (speeds
stalling speed at sea-level (OW): 80 [km/u]
stalling speed at sea-level (MTOW): 96 [km/u]
landing speed at sea-level: 94 [km/hr]
min. drag speed (max endurance) : 116 [km/hr] at 2438 [m](power :32 [%])
min. power speed (max range) : 126 [km/hr] at 2438 [m] (power:33 [%])
max. rate of climb speed : 120.5 [km/hr] at sea-level
cruising speed : 181 [km/hr] op 2438 [m] (power:59 [%])
design speed prop : 191 [km/hr]
maximum speed : 201 [km/hr] op 1525 [m] (power:83 [%])
climbing speed at sea-level : 377 [m/min]
calculation : *9* (regarding various performances)
take-off speed : 115.6 [km/u]
emergency/TO power : 470 [hp] at 2200 [rpm]
static prop wash : 105 [km/u]
take-off distance at sea-level : 290 [m]
lift/drag ratio : 10.97 [ ]
climb to 1500m with max payload : 9.31 [min]
climb to 3000m with max payload : 23.84 [min]
practical ceiling (operational weight) : 7183 [m] with flying weight :2016 [kg]
practical ceiling fully loaded : 4803 [m] with flying weight :2922 [kg]
max. dive speed : 475.2 [km/hr] at 3803 [m] height
turning speed at CLmax : 129.4 [km/u] at 50 [m] height
turn radius at 50m: 54 [m]
time needed for 360* turn 9.5 [seconds] at 50m
load factor at max. angle turn 2.63 ["g"]
D.H.18B G-EAWX
calculation *10* (action radius & endurance)
published range : 832 [km] with 1 crew and 692.5 [kg] useful load and 88.1 [%] fuel
range : 812 [km] with 1 crew and 700.0 [kg] useful load and 86.0 [%] fuel
max range theoretically with additional fuel tanks for total 1376.0 [litre] fuel : 2655.1 [km]
useful load with range 500km : 819 [kg]
production : 148.09 [tonkm/hour]
oil and fuel consumption per tonkm : 0.51 [kg]
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Accidents :
*16 August 1920 D.H.18 G-EARI of AT&T wrecked in a forced landing shortly after take-off from Croydon on 16 August 1920.
*On 7 April 1922 Goliath F-GEAD of Grands Express Aeriens made a Mid Air Crash above Poix/ Grandvillers, with a De Havilland DH18A G-EAWO which was on a mail flight from Croydon to Le Bourget. The 2 crew and 3 passenger aboard the Goliath died. The 2 crew of the DH18A also died in the crash. first MAC of two civil airplanes.
Literature :
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
Span 50ft 6 in = 15.39m chord 6ft 6 in = 1.98m length : 38ft 10in = 11.84m height : 13ft = 3.96m freight 2200 lbs = 998 kg, 255.75 cub.ft = 7.24m3, petrol 105 gallons = 477 litre, oil 10 gallons = 45.5 litre, weight empty with water 4040 lbs = 1832 kg with freight : 3880 lbs = 1760 kg > 8 seats + interior furbishing weight 72 kg crew 180 lbs = 81.6 kg
Useful load : 1440 lbs = 653 kg = 81.6 kg/pax petrol 761 lbs = 345 kg oil 95 lbs = 43 kg
Total weight fully loaded : 6516 lbs = 2956 kg area of main planes : 618 sq.ft = 57.41 m2
Speed at 1000 ft (305m) 128 mph = 206 km/hr Speed at 5000 ft (1524m) : 125 mph = 201 km/hr climb to 10000ft (3048m) : 20 mins Ceiling : 4877m endurance : 3.3 hrs
Range 413 miles : 665 km at 201 km/hr at 1525m. Stag Lane Aerodrome
(c) B van der Zalm 01 January 2021 contact : info.aircraftinvestigation@gmail.com python 3.7.4