Aircraft investigation >>>>>>> HOME PAGE
weight and performance calculations for the De Havilland D.H.91 Albatross
De Havilland D.H.91 Albatross
role : regional airliner
importance : ***
first flight : 20 May 1937 flown by Robert Wright at Hatfield aerodrome operational : October 1938
country : United-Kingdom
design : A.E.Hagg
production : 7 aircraft
general information :
Beautiful , nicely streamlined design. The air cooled engines had streamlined cowlings, cooling provided by ducts with inlets in the leading edge. Designed as transatlantic mailplane. But Imperial Airways ordered also a passenger variant. It was used on the route Croydon – Paris and Croydon – Brussels. Civil operations were soon halted with the outbreak of WWII with the aircraft pressed in RAF service.
As mail plane it had a range of 5310 km.
The passenger version had slotted flaps, while the mailplane had split flaps.
RAF 34 airfoil. Fuel capacity passenger version : one 270 and one 170 imp.gallon fuel tank under the belly (total 2000 litre)
users : Imperial airways
Registrations : G-AEVV “Faraday” prototype , G-AEVW “Franklin”, G-AFDI “Frobisher”, G-AFDJ “Falcon”, G-AFDK “Fortuna”, G-AFDL “Fingal”, G-AFDM “Fiona”.
crew : 4 passengers : 22
engine : 4 De Haviland Gipsy Twelve I air-cooled 12 -cylinder V-engine 415 [hp]
(309.5 KW) normal rating, supercharged engine, low blower, constant power to height :
2400 [m] and with 510 [hp](380.3 KW) available for take-off
dimensions :
wingspan : 32.01 [m], length : 21.83 [m], height : 6.78 [m]
wing area : 100.14 [m^2]
weights :
max.take-off weight : 13381 [kg]
empty weight operational : 9662 [kg] useful load : 2200 [kg]
performance :
maximum speed :362 [km/u] op 3400 [m]
cruise speed :344 [km/u] op 3400 [m]
service ceiling : 6200 [m]
range : 1477 [km]
description :
low-winged monoplane with retractable landing gear with tail wheel
tapered wing with slotted flaps airfoil : RAF 34
engines and landing gear attached to the wings, fuel tanks in the fuselage
construction : ply-balsa-ply sandwich construction used for the fuselage ( Port Orford
cedar ply ). Wing with large spruce box spar, wooden ribs and covered with “Tego”
airscrew :
four De Havilland constant speed full-feathering 2 -bladed tractor airscrews with max.
efficiency :0.74 [ ]
diameter airscrew 3.16 [m]
relative pitch (J) : 1.14 [ ]
power loading prop : 97.93 [KW/m]
theoretical pitch without slip : 4.09 [m]
blade angle prop at max.speed : 29.80 [ ]
tip-speed close to speed of sound (above Mach 0.85) > loose of efficiency
reduction : 0.67 [ ]
airscrew revs : 1634 [r.p.m.]
aerodynamic pitch at max. continuous speed 3.60 [m]
blade-tip speed at max.continuous speed : 288 [m/s]
propellor noise in flight : 100 [Db]
calculation : *1* (dimensions)
measured wing chord : 3.04 [m] at 50% wingspan
mean wing chord : 3.13 [m]
calculated average wing chord tapered wing with rounded tips: 3.03 [m]
wing aspect ratio : 10.2 []
seize (span*length*height) : 4738 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 21.0 [kg/hr]
fuel consumption(cruise speed) : 300.8 [kg/hr] (410.4 [litre/hr]) at 78 [%] power
distance flown for 1 kg fuel : 1.14 [km/kg] at 3400 [m] height, sfc : 311.0 [kg/kwh]
estimated total fuel capacity : 2000 [litre] (1466 [kg])
calculation : *3* (weight)
weight engine(s) dry with reduction gear : 1920.0 [kg] = 1.55 [kg/KW]
weight 151.8 litre oil tank : 12.90 [kg]
oil tank filled with 9.3 litre oil : 8.3 [kg]
oil in engine 6.9 litre oil : 6.2 [kg]
fuel in engine 8.4 litre fuel : 6.19 [kg]
weight 174.5 litre gravity patrol tank(s) : 26.2 [kg]
weight Burgess type silencers : 24.8 [kg]
weight cowling 12.4 [kg]
weight variable pitch control : 9.5 [kg]
weight airscrew(s) incl. boss & bolts : 160.8 [kg]
total weight propulsion system : 2178 [kg](16.3 [%])
***************************************************************
fuselage skeleton semi-monocoque (ply-wood-ply sandwich gauge : 6.99 [cm]): 1682 [kg]
cabin layout : pitch : 87 [cm] (2+2) seating in 5.5 rows
pax density : 1.70 [m2/pax]
weight 1 fire extinguisher : 3 [kg]
weight buffet : 19.7 [kg]
weight 13 windows : 11.7 [kg]
weight 4 emergency exits : 12.0 [kg]
weight door : 5.0 [kg]
passenger cabin max.width : 2.86 [m] cabin length : 5.91 [m] cabin height : 1.90 [m]
weight cabin furbishing : 96.4 [kg]
weight cabin floor : 96.7 [kg]
bracing : 431.7 [kg]
fuselage covering ( 137.1 [m2] plywood 9.2 [mm]) : 792.9 [kg]
fuselage (sound proof) isolation : 46.6 [kg]
weight radio transceiver equipment : 7.0 [kg]
weight radio direction finding (RDF) equipment : 5.0 [kg]
weight artificial horizon : 1.1 [kg]
weight instruments. : 13.0 [kg]
weight lighting : 5.5 [kg]
weight electricity generator : 12.2 [kg]
weight controls : 10.9 [kg]
weight seats : 130.0 [kg]
weight four 456 [litre] main fuel tanks empty : 146.0 [kg]
weight air conditioning : 33 [kg]
weight fuel lines : 7 [kg]
total weight fuselage : 3506 [kg](26.2 [%])
***************************************************************
weight 6.4 [mm] plywood wing covering : 410 [kg]
total weight wooden ribs (233 ribs) : 795 [kg]
weight engine mounts : 62 [kg]
load on front upper spar (clmax) per running metre : 2841.4 [N]
load on rear upper spar (vmax) per running metre : 1105.5 [N]
total weight 4 wooden spars : 1222 [kg]
weight wings : 2427 [kg]
weight wing/square meter : 24.24 [kg]
cantilever wing without bracing cables
weight rubber de-icing boots : 35.2 [kg]
weight fin & rudder (11.9 [m2]) : 290.1 [kg]
weight stabilizer & elevator (11.3 [m2]): 273.8 [kg]
total weight wing surfaces & bracing : 3088 [kg] (23.1 [%])
*******************************************************************
wheel pressure : 6690.5 [kg]
weight 2 Dunlop main wheels (1470 [mm] by 294 [mm]) : 418.6 [kg]
weight tailwheel(s) : 5.9 [kg]
weight Bendix wheel-brakes : 11.9 [kg]
weight Dowty shock absorbers : 15.8 [kg]
weight wheel electric operated retraction system : 56.2 [kg]
weight undercarriage with axle 334.8 [kg]
total weight landing gear : 843.2 [kg] (6.3 [%]
*******************************************************************
********************************************************************
calculated empty weight : 9615 [kg](71.9 [%])
weight oil for 5.2 hours flying : 108.5 [kg]
calculated operational weight empty : 9723 [kg] (72.7 [%])
published operational weight empty : 9662 [kg] (72.2 [%])
weight crew : 324 [kg]
weight fuel for 2.0 hours flying : 602 [kg]
weight catering : 37.8 [kg]
weight water : 15.1 [kg]
********************************************************************
operational weight empty: 10702 [kg](80.0 [%])
weight 22 passengers : 1694 [kg]
weight luggage : 268 [kg]
weight cargo : 238 [kg]
operational weight loaded: 12902 [kg](96.4 [%])
fuel reserve : 479.3 [kg] enough for 1.59 [hours] flying
operational weight fully loaded : 13381 [kg] with fuel tank filled for 74 [%]
published maximum take-off weight : 13381 [kg] (100.0 [%])
calculation : * 4 * (engine power)
power loading (Take-off) : 10.81 [kg/kW]
power loading (operational without useful load) : 8.65 [kg/kW]
power loading (Take-off) 1 PUF: 14.41 [kg/kW]
total power : 1237.9 [kW] at 2450 [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 : 1.9 [g]
design flight time : 3.44 [hours]
design cycles : 6045 sorties, design hours : 20769 [hours]
operational wing loading : 1048 [N/m^2]
wing stress (3 g) during operation : 130 [N/kg] at 3g emergency manoeuvre
calculation : *6* (angles of attack)
angle of attack zero lift : -1.32 ["]
max. angle of attack (stalling angle, clean) : 10.93 ["]
max. angle of attack (full flaps) : 12.93 ["]
angle of attack at max. speed : 1.30 ["]
calculation : *7* (lift & drag ratios
lift coefficient at angle of attack 0° : 0.12 [ ]
lift coefficient at max. speed : 0.24 [ ]
lift coefficient at max. angle of attack : 1.11 [ ]
max.lift coefficient full flaps : 1.33 [ ]
induced drag coefficient at max.speed : 0.0023 [ ]
drag coefficient at max. speed : 0.0191 [ ]
drag coefficient (zero lift) : 0.0169 [ ]
calculation : *8* (speeds
stalling speed at sea-level (OW loaded : 13080 [kg]): 156 [km/u]
stalling speed at sea-level with full flaps (normal landing weight): 131 [km/u]
landing speed at sea-level (normal landing weight : 10961 [kg]): 150 [km/hr]
max. rate of climb speed : 160 [km/hr] at sea-level
max. endurance speed : 164 [km/u] min.fuel/hr : 144 [kg/hr] at height : 610 [m]
max. range speed : 250 [km/u] min. fuel consumption : 0.775 [kg/km] at cruise height : 3962 [m]
cruising speed : 344 [km/hr] at 3400 [m] (power:87 [%])
max. continuous speed : 352.95 [km/hr]
maximum speed : 362 [km/hr] at 3400 [m] (power:98 [%])
climbing speed at sea-level (loaded) : 280 [m/min]
climbing speed at 1000 [m] with 1 engine out (PUF / MTOW) : 213 [m/min]
climbing speed at 1000 [m] with 2 engines out (2xPUF / MTOW) : 76 [m/min]
calculation : *9* (regarding various performances)
take-off speed : 189.4 [km/u]
emergency/TO power : 510 [hp] at 2716 [rpm]
static prop wash : 155 [km/u]
take-off distance at sea-level gras field : 547 [m]
take-off distance at sea-level over 15 [m] height : 689 [m]
landing run : 293 [m]
lift/drag ratio : 19.21 [ ]
climb to 1000m with max payload : 3.93 [min]
climb to 2000m with max payload : 7.98 [min]
climb to 3000m with max payload : 12.87 [min]
practical ceiling (operational weight empty 10702 [kg] ) : 7300 [m]
practical ceiling fully loaded (mtow- 30 min.fuel:13231 [kg] ) : 6000 [m]
calculation *10* (action radius & endurance)
published range : 1477 [km] with 4 crew and 2041.9 [kg] useful load and 88.1 [%] fuel
range : 1296 [km] with 4 crew and 2200.0 [kg] useful load and 77.3 [%] fuel
range : 1568 [km] with 22.0 passengers with each 12.2 [kg] luggage and 93.6 [%] fuel
Available Seat Kilometres (ASK) : 34494 [paskm]
max range theoretically with additional fuel tanks total 4879.8 [litre] fuel : 4613 [km]
useful load with range 500km : 3140 [kg]
useful load with range 500km : 22 passengers
production (theor.max load): 1080 [tonkm/hour]
production (useful load): 757 [tonkm/hour]
production (passengers): 7566 [paskm/hour]
oil and fuel consumption per tonkm : 0.30 [kg]
fuel cost per paskm : 0.043 [eur]
crew cost per paskm : 0.040 [eur]
economic hours : 12775 [hours] is less then design hours
time between engine failure : 401 [hr]
can continue fly on 3 engines, low risk for emergency landing for PUF
writing off per paskm : 0.074 [eur]
insurance per paskm : 0.003 [eur]
maintenance cost per paskm : 0.211 [eur]
direct operating cost per paskm : 0.370 [eur]
direct operating cost per tonkm (max. load): 2.593 [eur]
direct operating cost per tonkm (normal useful load): 3.700 [eur]
Literature :
Piston-engined airliners page 46,47,49
Praktisch handboek vliegtuigen deel 5 page 88,89
Jane’s all the world aircraft 1938 page 32c, 33c
Geillustreerde encyclopedie van de luchtvaart 1848-1939 page 228,229
De Havilland DH91 Albatross | BAE Systems | International
de Havilland Albatross - Wikipedia
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
(c) B van der Zalm 22 January 2022 contact : info.aircraftinvestigation@gmail.com python 3.7.4