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weight and performance calculations for the Hansa-Brandenburg KDW
Hansa-Brandenburg KDW
role : light maritime single-seat scout (ship based)
importance : ***
first flight : September 1916 operational : November 1916
country : Germany
design : Ernst Heinkel
production : 60 aircraft
general information :
KDW is the abbreviation of Kampf Doppeldecker Wasser. This general type classification was applied to the W.9 floatplane fighter designed by Ernst Heinkel in mid 1916. It was an adaption of the D.I landplane. Apart from the floats, the span was increased and an under fin was added to the rear-fuselage. It was put into service as defence fighter to protect seaplane bases on the Flanders and Adriatic coast. The first aircraft was completed in September 1916 but deliveries were slow and the 58th aircraft was only delivered February 1918 ! Production was done in small batches which differed from each other in rudders, radiators, floats and engines.
The prototypes were fitted with the 150hp Benz Bz III six-cylinder water-cooled engine, but apart from a preproduction batch of 10 similarly-powered aircraft, all subsequent examples of the KDW had the 160hp Maybach Mb III six-cylinder water-cooled engine. Directional stability was poor and recovery from a spin was very difficult. The Spandau MG was out pilot’s reach and when jammed it couldn’t be cleared during flight. Endurance : 2.5 hrs with 160 litre fuel
users : German Navy
registrations : 748, 783, 784, 912-921, 1067-1076 , 1380-1394, 1554-1573.
crew : 1
armament : 1 synchronized 7.92 [mm] (0.312 in) Spandau LMG 08/15 machine-gun
engine : 1 Maybach Mb.III liquid-cooled 6 -cylinder inline engine 160 [hp](117.7 KW)
dimensions :
wingspan : 9.25 [m], length : 8.0 [m], height : 3.35[m]
wing area : 29.15 [m^2]
weights :
max.take-off weight : 1040 [kg]
empty weight operational : 759 [kg] bombload : 0 [kg]
performance :
maximum speed : 172 [km/hr] at sea-level
climbing speed : 169 [m/min]
service ceiling : 4000 [m]
endurance : 3.1 [hours]
estimated action radius : 239 [km]
description :
1-bay two float biplane no tip floats
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 :0.63 [ ]
estimated diameter airscrew 2.76 [m]
angle of attack prop : 17.48 [ ]
reduction : 1.00 [ ]
airscrew revs : 1400 [r.p.m.]
pitch at Max speed 2.05 [m]
blade-tip speed at Vmax and max revs. : 208 [m/s]
calculation : *1* (dimensions)
mean wing chord : 1.58 [m]
calculated wing chord (rounded tips): 1.80 [m]
wing aspect ratio : 5.87 []
estimated gap : 1.47 [m]
gap/chord : 0.93 [ ]
seize (span*length*height) : 248 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 2.6 [kg/hr]
fuel consumption(cruise speed) : 33.4 [kg/hr] (45.5 [litre/hr]) at 69 [%] power
distance flown for 1 kg fuel : 4.64 [km/kg]
estimated total fuel capacity : 160 [litre] (117 [kg])
calculation : *3* (weight)
weight engine(s) dry : 282.4 [kg] = 2.40 [kg/KW]
weight 14 litre oil tank : 1.7 [kg]
oil tank filled with 0.9 litre oil : 0.8 [kg]
oil in engine 7 litre oil : 5.9 [kg]
fuel in engine 1 litre fuel : 0.6 [kg]
Early production KDW reg. 783 with 150 hp Benz Bz.III engine with car-type radiator
weight 19 litre gravity patrol tank(s) : 1.9 [kg]
weight radiator : 16.9 [kg]
weight exhaust pipes & fuel lines 11.4 [kg]
weight cowling 4.7 [kg]
weight airscrew(s) (wood) incl. boss & bolts : 19.0 [kg]
total weight propulsion system : 344 [kg](33.0 [%])
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fuselage skeleton (wood gauge : 6.32 [cm]): 72 [kg]
bracing : 3.6 [kg]
fuselage covering ( 9.4 [m2] doped linen fabric) : 3.0 [kg]
weight controls + indicators: 5.6 [kg]
weight seats : 3.0 [kg]
weight other details, lighting set, etc. : 5.1 [kg]
weight 140 [litre] main fuel tank empty : 13.5 [kg]
weight engine mounts & firewalls : 6 [kg]
total weight fuselage : 112 [kg](10.7 [%])
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weight wing covering (doped linen fabric) : 19 [kg]
total weight ribs (54 ribs) : 62 [kg]
load on front upper spar (clmax) per running metre : 923.4 [N]
load on rear upper spar (vmax) per running metre : 315.6 [N]
total weight 8 spars : 45 [kg]
weight wings : 126 [kg]
weight wing/square meter : 4.31 [kg]
weight 4 interplane struts & cabane : 11.4 [kg]
weight cables (46 [m]) : 3.3 [kg] (= 71 [gram] per metre)
diameter cable : 3.4 [mm]
weight fin & rudder (1.2 [m2]) : 5.5 [kg]
weight stabilizer & elevator (3.3 [m2]): 14.4 [kg]
total weight wing surfaces & bracing : 160 [kg] (15.4 [%])
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weight machine-gun(s) : 17.0 [kg]
weight ammunition magazine(s) :2.3 [kg]
weight Fokker Stangensteuerung synchronization gear : 1.0 [kg]
weight armament : 20 [kg]
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weight floats : 91 [kg] (8.7 [%])
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KDW with 160 hp Maybach engine and flush-type radiator mounted in the centre-section of the top wing with additional out splayed vee struts to brace the wingtips.
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calculated empty weight : 727 [kg](69.9 [%])
weight oil for 3.7 hours flying : 9.6 [kg]
weight cooling fluids : 24.2 [kg]
weight ammunition (500 rounds) : 14.1 [kg]
weight signal pistol with cartridges : 3.6 [kg]
weight automatic pistol with spare magazines : 1.2 [kg]
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calculated operational weight empty : 779 [kg] (74.9 [%])
published operational weight empty : 759 [kg] (73.0 [%])
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weight crew : 81 [kg]
weight fuel for 2.0 hours flying : 67 [kg]
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operational weight : 927 [kg](89.1 [%])
estimated bomb load : 50 [kg]
operational weight bombing mission : 977 [kg]
fuel reserve : 50 [kg] enough for 1.51 [hours] flying
The KDW prototype s/n 748 it had a car type radiator, no chimney exhaust > the 150 hp Benz engine on the prototype had stub exhaust pipes.
possible additional useful load : 13 [kg]
operational weight fully loaded : 1040 [kg] with fuel tank filled for 100 [%]
published maximum take-off weight : 1040 [kg] (100.0 [%])
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calculation : * 4 * (engine power)
power loading (operational without bombload) : 7.88 [kg/kW]
total power : 117.7 [kW] at 1400 [r.p.m]
calculation : *5* (loads)
manoeuvre load : 2.9 [g] at 1000 [m]
limit load : 3.5 [g] ultimate load : 5.2 [g] load factor : 2.2 [g]
design flight time : 2.47 [hours]
design cycles : 425 sorties, design hours : 1050 [hours]
operational wing loading : 312 [N/m^2]
wing stress (3 g) during operation : 217 [N/kg] at 3g emergency manoeuvre
calculation : *6* (angles of attack)
angle of attack zero lift : -1.27 ["]
max. angle of attack (stalling angle) : 13.08 ["]
angle of attack at max. speed : 1.60 ["]
calculation : *7* (lift & drag ratios
lift coefficient at angle of attack 0° :0.10 [ ]
lift coefficient at max. angle of attack : 1.13 [ ]
lift coefficient at max. speed : 0.23 [ ]
induced drag coefficient at max. speed : 0.0049 [ ]
drag coefficient at max. speed : 0.0380 [ ]
drag coefficient (zero lift) : 0.0331 [ ]
KDW with 160 hp Maybach engine
calculation : *8* (speeds
stalling speed at sea-level (OW): 77 [km/u]
landing speed at sea-level (OW without bombload): 92 [km/hr]
min. drag speed (max endurance) : 117 [km/hr] at 2000 [m](power :49 [%])
min. power speed (max range) : 123 [km/hr] at 2000 [m] (power:51 [%])
max. rate of climb speed : 108.2 [km/hr] at sea-level
cruising speed : 155 [km/hr] op 2000 [m] (power:69 [%])
design speed prop : 163 [km/hr]
maximum speed : 172 [km/hr] op 100 [m] (power:99 [%])
climbing speed at sea-level (without bombload) : 231 [m/min]
calculation : *9* (regarding various performances)
take-off distance at sea-level : 180 [m]
lift/drag ratio : 8.85 [ ]
max. practical ceiling : 4550 [m] with flying weight :858 [kg]
practical ceiling (operational weight) : 4050 [m] with flying weight :927 [kg] line 3385
practical ceiling fully loaded (mtow- 1 hour fuel) : 3500 [m] with flying weight :1007 [kg]
published ceiling (4000 [m]
climb to 1500m (without bombload) : 7.41 [min]
climb to 3000m (without bombload) : 19.40 [min]
max. dive speed : 390.1 [km/hr] at 2500 [m] height
load factor at max. angle turn 1.69 ["g"]
turn radius at 500m: 60 [m]
time needed for 360* turn 13.3 [seconds] at 500m
calculation *10* (action radius & endurance)
operational endurance : 3.51 [hours] with 1 crew and 63 [kg] useful (bomb)load and 100.0 [%] fuel
published endurance : 3.09 [hours] with 1 crew and possible useful (bomb) load : 76 [kg] and 88.1 [%] fuel
action radius : 370 [km] with 1 crew and 20[kg] photo camera/radio transmitter or bombload
KDW s/n 1562 is of the last batch that was built
max range theoretically with additional fuel tanks for total 271 [litre] fuel : 921 [km]
useful load with action-radius 250km : 91 [kg]
production : 14.05 [tonkm/hour]
oil and fuel consumption per tonkm : 2.56 [kg]
s/n 912
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Literature :
Praktisch handboek vliegtuigen deel 1 page 259
Fighters 1914-19 page 92
German aircraft of the first world war page 64,291
http://www.aviastar.org/air/germany/brandenburg_kdw.php
https://www.valka.cz/Hansa-Brandenburg-KDW-t68759
Jane’s fighting aircraft WWI page 136f
s/n 988 is a Brandenburg W 11 only 2 built (s/n 988-989), note the chimney type exhaust manifold as was fitted to the Benz-powered aircraft
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
The s/n 2051 on this KDW seems not correct
(c) B van der Zalm 09 February 2020 contact : info.aircraftinvestigation@gmail.com python 3.7.4