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weight and performance calculations for the De Havilland D.H.89 Dragon Rapide
The D.H.89 can be distinguished from the D.H.84 by the rounded wingtips and de streamlined wheel -fairings. Above airplane is a D.H.89A
De Havilland D.H.89 Dragon Rapide
role : light passenger aircraft
importance : ****
first flight : 17 April 1934 at Hatfield aerodrome , flown by H.S.Broad
operational : August 1934
country : United-Kingdom
design : Arthur Ernest Hagg
production : 205 for civil use before WWII, 500 military Dominie aircraft
general information :
twin-engined and scaled-down version of the DH86 Express . Popular light passenger
aircraft with nice flying qualities. Max. permissible speed : 260 km/hr for construction
safety. From February 1937 production aircraft were fitted with trailing edge flaps for
better landing performance, indicated as D.H.89A. The DH89A also had a landing light
in the nose and cabin heating. The aircraft was much used in WWII by the military as
trainer and liaison aircraft under the name Dominie .
Wing aspect ratio : 11.7 dihedral : 3 deg. Dunlop wheels , Dowty shock-absorbers,
Bendix wheel brakes. Engines starter : Rotax. 173 litre fuel tank in wing behind each
engine (total fuel capacity : 346 litre) 16 litre oil tank in each engine nacelle, cooled by
air scoops. Airfoil : RAF 34. Passenger cabin : length : 4.1m height : 1.4m
wide average : 1.2m. Take-off run : 265 [m] landing run : 156 [m] (with split flap).
Can stay in the air on 1 engine at 900 [m] height.
users : Railway Air Services , Isle of Man air services , Canadian Airways , West Coast Air services, RAF (Dominie)
crew : 1 passengers : 8
powerplant : 2 De Haviland Gipsy Six I air-cooled 6 -cylinder inverted inline piston
engine 200 [hp](149.1 KW) normal rating without supercharger
dimensions :
wingspan : 14.63 [m], length : 10.52 [m], height : 3.12 [m]
wing area : 31.2 [m^2]
weights :
max.take-off weight : 2495 [kg]
empty weight operational : 1465 [kg] useful load : 800 [kg]
performance :
maximum speed :253 [km/u] op 305 [m]
cruise speed :240 [km/u] op 305 [m]
service ceiling : 5100 [m]
range : 922 [km]
Measured chord at root : 2.07 [m] chord half wing : 1.50 [m] diam.prop : 2.19 [m] width fuselage : 1.38 [m] gap : 1.50 [m]
description :
2-bay biplane with fixed landing gear and tail strut
two spar upper and lower wing
engines and landing gear attached to the wings, fueltanks in the wings
construction : fuselage covered with plywood, wooden wing covered with fabric
airscrew :
two fixed pitch 2 -bladed tractor airscrews with max. efficiency :0.74 [ ]
estimated diameter airscrew 2.19 [m]
power loading prop : 68.10 [KW/m]
angle of attack prop : 19.18 [ ]
reduction : 1.00 [ ]
airscrew revs : 2350 [r.p.m.]
pitch at Max speed 1.75 [m]
blade-tip speed at max.continous speed : 278 [m/s]
propellor noise in flight : 96 [Db]
calculation : *1* (dimensions)
measured wing chord : 1.50 [m] at 50% wingspan
mean wing chord : 1.07 [m]
calculated wing chord (rounded tips): 1.25 [m]
wing aspect ratio (span*span/wing area) : 13.7 []
corrected wing aspect ratio : 11.7 []
estimated gap : 1.50 [m]
gap/chord : 1.41 [ ]
seize (span*length*height) : 480 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 5.1 [kg/hr]
fuel consumption(cruise speed) : 58.2 [kg/hr] (79.4 [litre/hr]) at 63 [%] power
distance flown for 1 kg fuel : 4.13 [km/kg] at 2550 [m] height, sfc : 310.1 [kg/kwh]
estimated total fuel capacity : 346 [litre] (253 [kg])
calculation : *3* (weight)
weight engine(s) dry : 426.0 [kg] = 1.43
[kg/KW]
weight 33.5 litre oil tank : 2.84 [kg]
oil tank filled with 2.2 litre oil : 2.0 [kg]
oil in engine 1.7 litre oil : 1.5 [kg]
fuel in engine 2.0 litre fuel : 1.49 [kg]
weight 33.8 litre gravity patrol tank(s) : 5.1 [kg]
weight Burgess type silencers : 6.0 [kg]
weight Rotax starter : 3.7 [kg]
weight cowling 6.0 [kg]
weight airscrew(s) incl. boss & bolts : 21.0 [kg]
total weight propulsion system : 475 [kg](19.1 [%])
***************************************************************
fuselage skeleton (wood gauge : 6.77 [cm]): 164 [kg]
cabin layout : pitch : 87 [cm] (1+1) seating in 4.0 rows
weight 1 fire extinguisher : 3 [kg]
weight 10 windows : 9.0 [kg]
weight door : 5.0 [kg]
passenger cabin max.width : 1.24 [m] cabin length : 4.10 [m] cabin height : 1.40 [m]
weight cabin furbishing : 12.8 [kg]
weight cabin floor : 27.7 [kg]
bracing : 17.5 [kg]
fuselage covering ( 34.8 [m2] plywood 5.6 [mm]) : 118.4 [kg]
fuselage (sound proof) isolation : 10.4 [kg]
weight radio transceiver equipment : 7.0 [kg]
weight Sperry gyro auto-pilot - course control equipment : 1.5 [kg]
weight instruments. : 6.0 [kg]
weight lighting : 2.0 [kg]
weight electricity generator : 2.0 [kg]
weight controls : 5.7 [kg]
weight seats : 45.0 [kg]
no cabin heating, only fresh air ventilation
weight air conditioning : 2 [kg]
total weight fuselage : 425 [kg](17.0 [%])
***************************************************************
weight wing covering (doped linen fabric) : 29 [kg]
total weight wooden ribs (191 ribs) : 148 [kg]
weight engine mounts : 15 [kg]
weight two 156 [litre] main fuel tanks empty : 25.0 [kg]
load on front upper spar (clmax) per running metre : 1256.4 [N]
load on rear upper spar (vmax) per running metre : 522.6 [N]
total weight 8 wooden spars : 114 [kg]
weight wings : 291 [kg]
weight wing/square meter : 9.34 [kg]
weight 8 interplane struts & cabane : 22.7 [kg]
weight cables (77 [m]) : 13.8 [kg] (= 179 [gram] per metre)
diameter cable : 5.4 [mm]
weight fin & rudder (2.5 [m2]) : 23.6 [kg]
weight stabilizer & elevator (3.5 [m2]): 33.0 [kg]
total weight wing surfaces & bracing : 424 [kg] (17.0 [%])
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Can only operate from paved runways
wheel pressure : 1247.5 [kg]
weight 2 Dunlop wheels (770 [mm] by 96 [mm]) : 38.5 [kg]
weight tailskid : 9.5 [kg]
weight Bendix wheel-brakes : 2.3 [kg]
weight Dowty shock absorbers : 3.0 [kg]
weight undercarriage with axle 80.8 [kg]
total weight landing gear : 134.1 [kg] (5.4 [%]
*******************************************************************
D.H.89 at Manchester (Ringway) airport, 1938
********************************************************************
calculated empty weight : 1459 [kg](58.5 [%])
weight oil for 4.6 hours flying : 23.3 [kg]
calculated operational weight empty : 1482 [kg] (59.4 [%])
published operational weight empty : 1465 [kg] (58.7 [%])
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weight crew : 81 [kg]
weight fuel for 2.0 hours flying : 116 [kg]
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operational weight empty: 1680 [kg](67.3 [%])
weight 8 passengers : 616 [kg]
weight luggage & freight : 184 [kg]
operational weight loaded: 2480 [kg](99.4 [%])
fuel reserve : 15.1 [kg] enough for 0.26 [hours] flying
operational weight fully loaded : 2495 [kg] with fuel tank filled for 52 [%]
published maximum take-off weight : 2495 [kg] (100.0 [%])
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calculation : * 4 * (engine power)
power loading (Take-off) : 8.36 [kg/kW]
power loading (operational without useful load) : 5.63 [kg/kW]
power loading (Take-off) 1 PUF: 16.73 [kg/kW]
total power : 298.3 [kW] at 2350 [r.p.m]
calculation : *5* (loads)
manoeuvre load : 3.4 [g] at 1000 [m]
limit load : 3.0 [g] ultimate load : 4.5 [g] load factor : 1.8 [g]
design flight time : 3.07 [hours]
design cycles : 4713 sorties, design hours : 14464 [hours]
operational wing loading : 528 [N/m^2]
wing stress (3 g) during operation : 170 [N/kg] at 3g emergency manoeuvre
calculation : *6* (angles of attack)
angle of attack zero lift : -1.30 ["]
max. angle of attack (stalling angle) : 10.43 ["]
angle of attack at max. speed : 0.65 ["]
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 : 1.08 [ ]
induced drag coefficient at max.speed : 0.0016 [ ]
drag coefficient at max. speed : 0.0355 [ ]
drag coefficient (zero lift) : 0.0339 [ ]
calculation : *8* (speeds
stalling speed at sea-level (OW loaded : 2437 [kg]): 122 [km/u]
landing speed at sea-level (normal landing weight : 1883 [kg]): 124 [km/hr]
max. rate of climb speed : 150 [km/hr] at sea-level
max. endurance speed : 131 [km/u] min. brpu : 38 [kg/hr] at height : 610 [m]
max. range speed : 190 [km/u] min. fuel consumption : 0.237 [kg/km] at cruise height :
4267 [m]
cruising speed : 240 [km/hr] at 2550 [m] (power:80 [%])
max. continuous speed : 246.67 [km/hr]
maximum speed : 253 [km/hr] at 305 [m] (power:108 [%])
climbing speed at sea-level (loaded) : 258 [m/min]
climbing speed at 1000 [m] with 1 engine out (reduced useful load : 400 [kg]) : 44
[m/min].
The Dragon Rapide has reliable engines > low risk of power unit failure (PUF) at TO.
If TO with MTOW at airport 1000 [m] above sea level a PUF would result in an
emergency landing. Take-off limits for hot & high ?
calculation : *9* (regarding various performances)
take-off speed : 148.4 [km/u]
static prop wash : 139 [km/u]
high wheel pressure, can only take off from paved runways
take-off distance at sea-level concrete runway : 267 [m]
take-off distance at sea-level over 15 [m] height : 412 [m]
landing run : 192 [m]
lift/drag ratio : 12.36 [ ]
climb to 1000m with max payload : 5.00 [min]
climb to 2000m with max payload : 11.80 [min]
climb to 3000m with max payload : 22.18 [min]
practical ceiling (operational weight 1680 [kg] ) : 6500 [m]
practical ceiling fully loaded (mtow- 30 min.fuel:2466 [kg] ) : 4400 [m]
calculation *10* (action radius & endurance)
published range : 922 [km] with 1 crew and 708.3 [kg] useful load and 88.1 [%] fuel
range : 543 [km] with 1 crew and 800.0 [kg] useful load and 51.9 [%] fuel
range : 973 [km] with 8.0 passengers with each 10 [kg] luggage and 93.0 [%] fuel
Available Seat Kilometres (ASK) : 7782 [paskm]
max range theoretically with additional fuel tanks total 1270.9 [litre] fuel : 3924 [km]
useful load with range 500km : 810 [kg]
useful load with range 500km : 8 passengers
production (useful load): 195 [tonkm/hour]
production (passengers): 1923 [paskm/hour]
oil and fuel consumption per tonkm : 0.32 [kg]
fuel cost per paskm : 0.032 [eur]
crew cost per paskm : 0.077 [eur]
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economic hours : 12775 [hours] is less then design hours
time between engine failure : 2940 [hr]
can continue fly on 1 engine, low risk for emergency landing for PUF
writing off per paskm : 0.044 [eur]
insurance per paskm : 0.001 [eur]
rigging cost per paskm : 0.039 [eur]
maintenance cost per paskm : 0.191 [eur]
direct operating cost per paskm : 0.345 [eur]
direct operating cost per tonkm : 3.448 [eur]
Literature :
Praktisch handboek vliegtuigen deel 2 page 108,109
Piston-engined airliners page 39, 41
Jane’s fighting aircraft of WWII page 117
Encyclopedie van de luchtvaart1848-1939 page 244,245
de Havilland Dragon Rapide - 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