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weight and performance calculations for the Junkers G.24
Junkers G.24
role : multi-engined passenger aircraft
importance : ****
first flight : 19 September 1924 operational : May 1926
country : Germany
design : Ernst Zindel
production : 92 aircraft
general information :
All-metal monoplane airliner , further development of the successful F.13. At first it was designed as single engine airplane. But the Treaty of Versailles only allowed low powered engines, so for this reason 3 low power engines were installed. The 3 engines had a benefit that with one engine out the airplane could continue to fly and even climb. It was the first successful 3-engined airliner. A single engine aircraft was more efficient but when the engine failed an emergency landing had to be made, two engined aircraft could not stay in the air with one engine out or only with overpowered engines. The three engined aircraft was the safest solution in this period, although it gave higher operating cost. The 3-engined G.24 was safe to fly at night and Lufthansa started to use the aircraft at the route Berlin – Konigsberg in the night
The G.24 set several records. Fritz Horn flew 2020 km with a payload of 1000 kg in 14 hrs 23 min, average speed 140 km/hr.
users : Lufthansa
crew : 3 passengers : 9
engine : 3 Junkers L5 liquid-cooled 6 -cylinder inline engine 310 [hp](231.2 KW)
without supercharger
dimensions :
wingspan : 29.37 [m], length : 15.8 [m], height : 5.8[m]
wing area : 99.0 [m^2]
weights :
max.take-off weight : 6500 [kg]
empty weight operational : 4330 [kg] useful load : 1000 [kg]
performance :
maximum speed :202 [km/u] op 100 [m]
cruise speed :182 [km/u] op 100 [m]
service ceiling : 4700 [m]
range : 1000 [km]
description :
low-wing monoplane with fixed landing gear and tail strut
two spar tapered wing
2 engines attached to the wings 1 in the fuselage, landing gear attached to the wings, useful load inside the fuselage
fuel tanks in the wings
airscrew :
three fixed pitch 2 -bladed tractor airscrews with max. efficiency :0.67 [ ]
estimated diameter airscrew 3.18 [m]
angle of attack prop : 17.52 [ ]
reduction : 1.00 [ ]
airscrew revs : 1425 [r.p.m.]
pitch at Max speed 2.37 [m]
blade-tip speed at Vmax and max revs. : 244 [m/s]
calculation : *1* (dimensions)
measured wing chord at root : 4.16 [m]
mean wing chord : 3.37 [m]
wing aspect ratio : 8.71 []
seize (span*length*height) : 2691 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 10.4 [kg/hr]
fuel consumption(cruise speed) : 147.1 [kg/hr] (200.7 [litre/hr]) at 65 [%] power
distance flown for 1 kg fuel : 1.24 [km/kg] at 2350 [m] cruise height, sfc : 327.1 [kg/kwh]
estimated total fuel capacity : 1252 [litre] (918 [kg])
Side view is of a military variant with radial engines (K-30 prototype with Gnome Rhone engines ?)
Measured chord at wing root : 4.16m
calculation : *3* (weight)
weight engine(s) dry : 1002.0 [kg] = 1.44 [kg/KW]
weight 93.7 litre oil tank : 7.97 [kg]
oil tank filled with 5.2 litre oil : 4.7 [kg]
oil in engine 38.6 litre oil : 34.7 [kg]
fuel in engine 4.7 litre fuel : 3.47 [kg]
weight 85.3 litre gravity patrol tank(s) : 12.8 [kg]
weight radiator : 104.0 [kg]
weight exhaust pipes & fuel lines 26.9 [kg]
weight inertia starter : 5.7 [kg]
weight cowling 9.2 [kg]
weight airscrew(s) (wood) incl. boss & bolts : 93.4 [kg]
total weight propulsion system : 1297 [kg](20.0 [%])
***************************************************************
fuselage aluminium frame : 699 [kg]
cabin layout : pitch : 87 [cm] (1+1) seating in 4.5 rows
weight toilet : 5 [kg]
weight 9.0 windows : 8.10 [kg]
passenger cabin width : 1.53 [m] cabin length : 3.92 [m] cabin height : 1.90 [m]
weight cabin furbishing : 24.94 [kg]
weight cabin floor : 38.30 [kg]
bracing : 139.6 [kg]
fuselage covering ( 47.2 [m2] duraluminium 0.75 mm) : 92.5 [kg]
weight radio navigation equipment : 7.0 [kg]
weight instruments. : 4.0 [kg]
weight lighting : 2.2 [kg]
weight controls : 9.0 [kg]
weight seats : 60.0 [kg]
weight air conditioning : 14 [kg]
weight engine mount and firewall : 12 [kg]
total weight fuselage : 1115 [kg](17.2 [%])
***************************************************************
weight wing covering (painted aluminium 0.75 mm) : 401 [kg]
total weight ribs (98 ribs) : 232 [kg]
weight engine mounts : 23 [kg]
weight fuel tanks empty for total 1166 [litre] fuel : 93 [kg]
load on front upper spar (clmax) per running metre : 2039.6 [N]
load on rear upper spar (vmax) per running metre : 624.3 [N]
total weight 4 spars : 437 [kg]
weight wings : 1069 [kg]
weight wing/square meter : 10.80 [kg]
cantilever wing without bracing cables
weight fin & rudder (10.0 [m2]) : 109.6 [kg]
weight stabilizer & elevator (11.1 [m2]): 121.0 [kg]
total weight wing surfaces & bracing : 1416 [kg] (21.8 [%])
*******************************************************************
wheel pressure : 3250.0 [kg]
weight 2 wheels (1230 [mm] by 154 [mm]) : 145.2 [kg]
weight tailskid : 18.3 [kg]
weight undercarriage with axle 230.8 [kg]
total weight landing gear : 394.3 [kg] (6.1 [%]
*******************************************************************
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calculated empty weight : 4223 [kg](65.0 [%])
weight oil for 6.6 hours flying : 68.6 [kg]
weight cooling fluids : 149.8 [kg]
calculated operational weight empty : 4441 [kg] (68.3 [%])
published operational weight empty : 4330 [kg] (66.6 [%])
___o___
"
weight crew : 243 [kg]
weight fuel for 2.0 hours flying : 294 [kg]
********************************************************************
operational weight empty: 4978 [kg](76.6 [%])
weight 9 passengers : 693 [kg]
weight luggage & freight : 307 [kg]
operational weight loaded: 5978 [kg](76.6 [%])
fuel reserve : 521.6 [kg] enough for 3.54 [hours] flying
operational weight fully loaded : 6500 [kg] with fuel tank filled for 89 [%]
published maximum take-off weight : 6500 [kg] (100.0 [%])
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calculation : * 4 * (engine power)
power loading (Take-off) : 9.37 [kg/kW]
power loading (operational without useful load) : 7.18 [kg/kW]
power loading (Take-off) 1 PUF: 14.06 [kg/kW]
total power : 693.5 [kW] at 1425 [r.p.m]
calculation : *5* (loads)
manoeuvre load : 2.6 [g] at 1000 [m]
limit load : 2.5 [g] ultimate load : 3.8 [g] load factor : 2.5 [g]
design flight time : 3.85 [hours]
design cycles : 7004 sorties, design hours : 26939 [hours]
operational wing loading : 493 [N/m^2]
wing stress (3 g) during operation : 137 [N/kg] at 3g emergency manoeuvre
calculation : *6* (angles of attack)
angle of attack zero lift : -1.95 ["]
max. angle of attack (stalling angle) : 11.13 ["]
angle of attack at max. speed : 1.00 ["]
calculation : *7* (lift & drag ratios
lift coefficient at angle of attack 0° :0.17 [ ]
lift coefficient at max. angle of attack : 1.14 [ ]
lift coefficient at max. speed : 0.26 [ ]
induced drag coefficient at max. speed : 0.0032 [ ]
drag coefficient at max. speed : 0.0428 [ ]
drag coefficient (zero lift) : 0.0396 [ ]
Note the 4-bladed props, in general it had 2-bladed props.
calculation : *8* (speeds
stalling speed at sea-level (OW loaded : 6353 [kg]): 108 [km/u]
landing speed at sea-level: 127 [km/hr]
min. drag speed (max endurance) : 136 [km/hr] at 2350 [m](power :45 [%])
min. power speed (max range) : 136 [km/hr] at 2350 [m] (power:45 [%])
max. rate of climb speed : 120.9 [km/hr] at sea-level
cruising speed : 182 [km/hr] op 2350 [m] (power:70 [%])
design speed prop : 192 [km/hr]
maximum speed : 202 [km/hr] op 100 [m] (power:103 [%])
climbing speed at sea-level : 309 [m/min]
calculation : *9* (regarding various performances)
take-off speed : 131.0 [km/u]
emergency/TO power : 345 [hp] at 1621 [rpm]
static prop wash : 144 [km/u]
take-off distance at sea-level : 217 [m]
lift/drag ratio : 11.39 [ ]
climb to 1000m with max payload : 6.01 [min]
climb to 2000m with max payload : 14.57 [min]
climb to 3000m with max payload : 26.40 [min]
practical ceiling (operational weight 4978 [kg] ) : 5833 [m]
practical ceiling fully loaded (mtow- 30 min.fuel:6426 [kg] ) : 4383 [m]
max. dive speed : 550.2 [km/hr] at 3383 [m] height
turning speed at CLmax : 148.5 [km/u] at 50 [m] height
turn radius at 50m: 79 [m]
time needed for 360* turn 12.1 [seconds] at 50m
load factor at max. angle turn 2.40 ["g"]
calculation *10* (action radius & endurance)
published range : 1000 [km] with 3 crew and 1007.4 [kg] useful load and 88.1 [%] fuel
range : 1009 [km] with 3 crew and 1000.0 [kg] useful load and 88.9 [%] fuel
range : 1278 [km] with 9.0 passengers with each 10 [kg] luggage and 112.6 [%] fuel
Available Seat Kilometers (ASK) : 11498 [paskm]
max range theoretically with additional fuel tanks for total 2698.3 [litre] fuel : 2446.5
[km]
useful load with range 500km : 1574 [kg]
useful load with range 500km : 9 passengers
production (useful load): 286.40 [tonkm/hour]
production (passengers): 1638.00 [paskm/hour]
oil and fuel consumption per tonkm : 0.55 [kg]
oil and fuel consumption per paskm : 0.10 [kg]
fuel cost per paskm : 0.10 [eur]
crew cost per paskm : 0.09 [eur]
I=I°_°°°°/
°
economic hours : 12775 [hours] is less then design hours
time between engine failure : 185 [hr]
low risk for emergency landing, can continue flying with 1 engine out
writing off per paskm : 0.17 [eur]
insurance per paskm : 0.0422 [eur]
maintenance cost per paskm : 0.4064 [eur]
direct operating cost per paskm : 0.80 [eur]
serious accidents :
Literature :
Praktisch handbook vliegtuigen deel 2 page 124
Piston-engined airliners page 17
Junkers G.24 | Bureau of Aircraft Accidents Archives (baaa-acro.com)
Ongevallen/incidenten 1932 (hdekker.info)
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/
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(c) B van der Zalm 10 May 2021 contact : info.aircraftinvestigation@gmail.com python 3.7.4