Aircraft investigation >>>>>>> HOME PAGE
weight and performance calculations for the De Havilland D.H.83 Fox Moth
De Havilland D.H.83 Fox Moth
role : air taxi
importance : ****
first flight : 29 January 1932 operational : October 1932
country : United-Kingdom
design : A.E.Hagg
production : 155 aircraft
general information :
Popular light air taxi and bush plane.
users : Hilmans Airways
crew : 1 passengers : 3
powerplant : 1 De Havilland Gipsy III
air-cooled 4 -cylinder inverted inline piston engine 108 [hp](80.5 KW)
normal rating and with 120 [hp](89.5 KW) available for take-off
dimensions :
wingspan : 9.41 [m], length : 7.85 [m], height : 2.68 [m]
wing area : 24.29 [m^2]
weights :
max.take-off weight : 907 [kg]
empty weight operational : 486 [kg] useful load : 290 [kg]
performance :
maximum speed :171 [km/hr] at sea-level
cruise speed :162 [km/u] op 100 [m]
service ceiling : 3900 [m]
range : 684 [km]
description :
1-bay biplane with fixed landing gear and tail strut
two spar upper and lower wing
airfoil : RAF 15
engines, landing gear, fuel and useful load in or attached to the fuselage
airscrew :
fixed pitch 2 -bladed tractor airscrew with max. efficiency :0.69 [ ]
estimated diameter airscrew 1.97 [m]
power loading prop : 40.88 [KW/m]
angle of attack prop : 17.07 [ ]
reduction : 1.00 [ ]
airscrew revs : 2000 [r.p.m.]
pitch at Max speed 1.39 [m]
blade-tip speed at max.continous speed : 211 [m/s]
propellor noise in flight : 74 [Db]
calculation : *1* (dimensions)
measured wing chord : 1.33 [m] at 50% wingspan
mean wing chord : 1.29 [m]
calculated wing chord (rounded tips): 1.45 [m]
wing aspect ratio : 7.3 []
estimated gap : 1.52 [m]
gap/chord : 1.18 [ ]
seize (span*length*height) : 198 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 2.0 [kg/hr]
fuel consumption(cruise speed) : 16.7 [kg/hr] (22.8 [litre/hr]) at 69 [%] power
distance flown for 1 kg fuel : 9.71 [km/kg] at 1950 [m] height, sfc : 301.9 [kg/kwh]
estimated total fuel capacity : 109 [litre] (80 [kg])
calculation : *3* (weight)
weight engine(s) dry : 139.0 [kg] = 1.73 [kg/KW]
weight 13.3 litre oil tank : 1.13 [kg]
oil tank filled with 0.6 litre oil : 0.5 [kg]
oil in engine 0.4 litre oil : 0.4 [kg]
fuel in engine 0.5 litre fuel : 0.40 [kg]
weight 9.7 litre gravity patrol tank(s) : 1.5 [kg]
weight Eclipse inertia starter : 2.0 [kg]
weight cowling 3.2 [kg]
weight airscrew(s) incl. boss & bolts : 5.2 [kg]
total weight propulsion system : 153 [kg](16.9 [%])
***************************************************************
fuselage skeleton (wood gauge : 4.22 [cm]): 64 [kg]
cabin layout : pitch : 87 [cm] (1+1) seating in 1.5 rows
weight 5 windows : 4.5 [kg]
weight door : 5.0 [kg]
passenger cabin max.width : 1.01 [m] cabin length : 1.93 [m] cabin height : 1.41 [m]
weight cabin furbishing : 4.3 [kg]
weight cabin floor : 8.5 [kg]
bracing : 3.5 [kg]
fuselage covering ( 11.6 [m2] doped linen fabric) : 3.5 [kg]
weight instruments. : 3.5 [kg]
weight lighting : 1.1 [kg]
weight electricity generator : 0.8 [kg]
weight controls : 4.4 [kg]
weight seats : 20.0 [kg]
weight 99 [litre] main fuel tank empty : 8.0 [kg]
weight air conditioning : 3 [kg]
weight engine mounts & firewalls : 4 [kg]
total weight fuselage : 137 [kg](15.1 [%])
***************************************************************
weight wing covering (doped linen fabric) : 23 [kg]
total weight wooden ribs (57 ribs) : 54 [kg]
total weight 8 wooden spars : 34 [kg]
weight wings : 111 [kg]
weight wing/square meter : 4.59 [kg]
weight 4 interplane struts & cabane : 10.9 [kg]
weight cables (47 [m]) : 2.5 [kg] (= 54 [gram] per metre)
diameter cable : 3.0 [mm]
weight fin & rudder (1.0 [m2]) : 4.9 [kg]
weight stabilizer & elevator (2.7 [m2]): 12.7 [kg]
total weight wing surfaces & bracing : 142 [kg] (15.7 [%])
*******************************************************************
Can only operate from paved runways
wheel pressure : 453.5 [kg]
weight 2 wheels (470 [mm] by 94 [mm]) : 17.7 [kg]
weight tailskid : 3.4 [kg]
weight undercarriage with axle 26.9 [kg]
total weight landing gear : 48.1 [kg] (5.3 [%]
*******************************************************************
********************************************************************
calculated empty weight : 481 [kg](53.0 [%])
weight oil for 5.1 hours flying : 10.2 [kg]
calculated operational weight empty : 491 [kg] (54.1 [%])
published operational weight empty : 486 [kg] (53.6 [%])
_____________
| o |
-------------
"
weight crew : 81 [kg]
weight fuel for 2.0 hours flying : 33 [kg]
********************************************************************
operational weight empty: 605 [kg](66.7 [%])
weight 3 passengers : 231 [kg]
weight luggage & freight : 59 [kg]
operational weight loaded: 895 [kg](98.7 [%])
fuel reserve : 11.8 [kg] enough for 0.70 [hours] flying
operational weight fully loaded : 907 [kg] with fuel tank filled for 57 [%]
published maximum take-off weight : 907 [kg] (100.0 [%])
||
I||==|
||
calculation : * 4 * (engine power)
power loading (Take-off) : 11.26 [kg/kW]
power loading (operational without useful load) : 7.51 [kg/kW]
total power : 80.5 [kW] at 2000 [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 : 1.8 [g]
design flight time : 3.37 [hours]
design cycles : 4061 sorties, design hours : 13679 [hours]
operational wing loading : 244 [N/m^2]
wing stress (3 g) during operation : 160 [N/kg] at 3g emergency manoeuvre
calculation : *6* (angles of attack)
angle of attack zero lift : -1.48 ["]
max. angle of attack (stalling angle) : 12.60 ["]
angle of attack at max. speed : 0.72 ["]
calculation : *7* (lift & drag ratios
lift coefficient at angle of attack 0° : 0.12 [ ]
lift coefficient at max. speed : 0.18 [ ]
lift coefficient at max. angle of attack : 1.14 [ ]
induced drag coefficient at max.speed : 0.0028 [ ]
drag coefficient at max. speed : 0.0370 [ ]
drag coefficient (zero lift) : 0.0343 [ ]
calculation : *8* (speeds
stalling speed at sea-level (OW loaded : 890 [kg]): 82 [km/u]
landing speed at sea-level (normal landing weight : 724 [kg]): 85 [km/hr]
max. rate of climb speed : 107 [km/hr] at sea-level
max. endurance speed : 102 [km/u] min. fuel/hr : 14 [kg/hr] at height : 610 [m]
max. range speed : 138 [km/u] min. fuel consumption : 0.121 [kg/km] at 3048 [m]
cruising speed : 162 [km/hr] at 1950 [m] (power:92 [%])
max. continuous speed : 166.72 [km/hr]
maximum speed : 171 [km/hr] at 100 [m] (power:115 [%])
climbing speed at sea-level (loaded) : 134 [m/min]
calculation : *9* (regarding various performances)
take-off speed : 98.9 [km/u]
emergency/TO power : 120 [hp] at 2108 [rpm]
static prop wash : 117 [km/u]
high wheel pressure, can only take off from paved runways
take-off distance at sea-level concrete runway : 133 [m]
take-off distance at sea-level over 15 [m] height : 332 [m]
landing run : 87 [m]
lift/drag ratio : 9.14 [ ]
climb to 1000m with max payload : 11.49 [min]
climb to 2000m with max payload : 33.01 [min]
practical ceiling (operational weight 605 [kg] ) : 5000 [m]
practical ceiling fully loaded (mtow- 30 min.fuel:899 [kg] ) : 2500 [m]
calculation *10* (action radius & endurance)
published range : 684 [km] with 1 crew and 264.8 [kg] useful load and 88.1 [%] fuel
range : 439 [km] with 1 crew and 290.0 [kg] useful load and 56.6 [%] fuel
range : 721 [km] with 3.0 passengers with each 10 [kg] luggage and 92.8 [%] fuel
Available Seat Kilometres (ASK) : 2162 [paskm]
max range theoretically with additional fuel tanks total 457.4 [litre] fuel : 2827 [km]
useful load with range 500km : 284 [kg]
useful load with range 500km : 3 passengers
production (useful load): 46 [tonkm/hour]
production (passengers): 487 [paskm/hour]
none or very little cargo capability
can use normal petrol, aviation grade fuel not required
oil and fuel consumption per tonkm : 0.41 [kg]
fuel cost per paskm : 0.041 [eur]
crew cost per paskm : 0.325 [eur]
economic hours : 12775 [hours] is less then design hours
time between engine failure : 6640 [hr]
in case of engine failure only option is emergency landing
writing off per paskm : 0.061 [eur]
insurance per paskm : 0.001 [eur]
rigging cost per paskm : 0.090 [eur]
maintenance cost per paskm : 0.465 [eur]
direct operating cost per paskm : 0.893 [eur]
direct operating cost per tonkm : 8.928 [eur]
Literature :
Piston-engined airliners page 39
de Havilland Fox Moth - 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 28 November 2021 contact : info.aircraftinvestigation@gmail.com python 3.7.4
