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weight and performance calculations for the Junkers F 13a
Junkers F 13a
role : light passenger aircraft
importance : *****
first flight : 25 June 1919, Dessau, pilot : Emil Monz operational : February 1920
country : Germany
design : Otto Reuter
production : 322 aircraft
general information :
Reliable small airliner. It was built in large numbers and used by many airlines in 12 different countries. It was of all-metal construction, and proved to be very strong during its operational life. Also the selling & hiring policy with good conditions of Junkers added to the popularity. The metal frame was covered with a corrugated and stressed duraluminium skin. Hugo Junkers was a pioneer for building metal aircraft, the first one being the J.1, making its first flight December 1915. Commercial F 13’s were in service for more then 30 years ! The last being retired in 1951 in Brazil.
users : 30 airlines
crew : 2 passengers : 4
engine : 1 BMW IIIA liquid-cooled 6 -cylinder inline engine 201 [hp](149.9 KW)
dimensions :
wingspan : 17.75 [m], length : 9.6 [m], height : 4.5[m]
wing area : 44.0 [m^2]
weights :
max.take-off weight : 1730 [kg]
empty weight operational : 1150 [kg] useful load : 340 [kg]
performance :
maximum speed :177 [km/u] op 500 [m]
cruise speed :159 [km/u] op 500 [m]
service ceiling : 4000 [m]
range : 560 [km]
description :
low-wing monoplane with fixed landing gear and tail strut
two spar wing
engines, landing gear, fuel and useful load in or attached to the fuselage
airscrew :
fixed pitch 2 -bladed tractor airscrew with max. efficiency :0.65 [ ]
diameter airscrew 3.04 [m]
angle of attack prop : 19.45 [ ]
reduction : 1.00 [ ]
airscrew revs : 1400 [r.p.m.]
pitch at Max speed 2.11 [m]
blade-tip speed at Vmax and max revs. : 192 [m/s]
calculation : *1* (dimensions)
wing chord : 2.56 [m]
mean wing chord : 2.48 [m]
calculated wing chord (rounded leading edge tips): 2.59 [m]
wing aspect ratio : 7.16 []
seize (span*length*height) : 767 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 3.7 [kg/hr]
fuel consumption(cruise speed) : 40.7 [kg/hr] (55.6 [litre/hr]) at 90 [%] power
distance flown for 1 kg fuel : 3.91 [km/kg] at 2000 [m] cruise height, sfc : 302.0 [kg/kwh]
estimated total fuel capacity : 221.76 [litre] (162.55 [kg])
calculation : *3* (weight)
weight engine(s) dry : 293.0 [kg] = 1.95 [kg/KW]
weight 21.4 litre oil tank : 1.82 [kg]
oil tank filled with 1.1 litre oil : 1.0 [kg]
oil in engine 8.3 litre oil : 7.5 [kg]
fuel in engine 1.0 litre fuel : 0.75 [kg]
weight 23.6 litre gravity patrol tank(s) : 3.5 [kg]
PP-VAF operated in Brazil
weight radiator : 27.7 [kg]
weight exhaust pipes & fuel lines 14.1 [kg]
weight self-starter : 3.7 [kg]
weight cowling 6.0 [kg]
weight airscrew(s) (wood) incl. boss & bolts : 55.4 [kg]
total weight propulsion system : 413 [kg](23.9 [%])
***************************************************************
fuselage aluminium frame : 91 [kg]
cabin layout : pitch : 87 [cm] (1+1) seating in 2.0 rows
weight 4.0 windows : 3.60 [kg]
passenger cabin width : 1.32 [m] cabin length : 1.74 [m] cabin height : 1.90 [m]
weight cabin furbishing : 9.01 [kg]
weight cabin floor : 14.68 [kg]
bracing : 7.7 [kg]
fuselage covering ( 17.4 [m2] aluminium 1mm) : 33.9 [kg]
weight instruments. : 2.5 [kg]
weight lighting : 1.1 [kg]
weight controls : 5.9 [kg]
weight seats : 30.0 [kg]
weight 198 [litre] main fuel tank empty : 15.9 [kg]
weight air conditioning : 6 [kg]
weight engine mounts & firewalls : 7 [kg]
total weight fuselage : 229 [kg](13.2 [%])
***************************************************************
weight wing covering (painted aluminium 0.75 mm) : 178 [kg]
total weight ribs (36 ribs) : 82 [kg]
load on front upper spar (clmax) per running metre : 482.7 [N]
load on rear upper spar (vmax) per running metre : 262.9 [N]
The pilot had only a small windscreen, he still was with his nose in the open air.
total weight 4 spars : 70 [kg]
weight wings : 330 [kg]
weight wing/square meter : 7.50 [kg]
cantilever wing without bracing (cables)
weight fin & rudder (3.7 [m2]) : 28.0 [kg]
weight stabilizer & elevator (5.0 [m2]): 37.5 [kg]
total weight wing surfaces & bracing : 396 [kg] (22.9 [%])
*******************************************************************
wheel pressure : 865.0 [kg]
weight 2 wheels (820 [mm] by 126 [mm]) : 45.3 [kg]
weight tailskid : 2.7 [kg]
weight undercarriage with axle 26.6 [kg]
total weight landing gear : 74.7 [kg] (4.3 [%]
*******************************************************************
********************************************************************
calculated empty weight : 1112 [kg](64.3 [%])
weight oil for 4.2 hours flying : 15.8 [kg]
weight cooling fluids : 32.4 [kg]
calculated operational weight empty : 1160 [kg] (67.1 [%])
published operational weight empty : 1150 [kg] (66.5 [%])
___o___
"
weight crew : 162 [kg]
weight fuel for 1.5 hours flying : 61 [kg]
********************************************************************
operational weight empty: 1383 [kg](80.0 [%])
weight 4 passengers : 308 [kg]
weight luggage & freight : 32 [kg]
operational weight loaded: 1723 [kg](80.0 [%])
fuel reserve : 6.8 [kg] enough for 0.17 [hours] flying
operational weight fully loaded : 1730 [kg] with fuel tank filled for 42 [%]
published maximum take-off weight : 1730 [kg] (100.0 [%])
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calculation : * 4 * (engine power)
power loading (Take-off) : 11.54 [kg/kW]
power loading (operational without useful load) : 9.23 [kg/kW]
total power : 149.9 [kW] at 1400 [r.p.m]
calculation : *5* (loads)
manoeuvre load : 3.2 [g] at 1000 [m]
limit load : 3.0 [g] ultimate load : 4.5 [g] load factor : 1.4 [g]
design flight time : 2.81 [hours]
design cycles : 1707 sorties, design hours : 4800 [hours]
operational wing loading : 308 [N/m^2]
wing stress (3 g) during operation : 123 [N/kg] at 3g emergency manoeuvre
calculation : *6* (angles of attack)
angle of attack zero lift : -1.20 ["]
max. angle of attack (stalling angle) : 12.58 ["]
angle of attack at max. speed : 1.42 ["]
calculation : *7* (lift & drag ratios
lift coefficient at angle of attack 0° :0.10 [ ]
lift coefficient at max. angle of attack : 1.15 [ ]
lift coefficient at max. speed : 0.22 [ ]
induced drag coefficient at max. speed : 0.0028 [ ]
drag coefficient at max. speed : 0.0317 [ ]
drag coefficient (zero lift) : 0.0288 [ ]
calculation : *8* (speeds
stalling speed at sea-level (OW): 75 [km/u]
stalling speed at sea-level (MTOW): 84 [km/u]
landing speed at sea-level: 89 [km/hr]
min. drag speed (max endurance) : 107 [km/hr] at 2000 [m](power :40 [%])
min. power speed (max range) : 116 [km/hr] at 2000 [m] (power:42 [%])
max. rate of climb speed : 105.7 [km/hr] at sea-level
cruising speed : 159 [km/hr] op 2000 [m] (power:69 [%])
design speed prop : 168 [km/hr]
maximum speed : 177 [km/hr] op 500 [m] (power:100 [%])
climbing speed at sea-level : 222 [m/min]
calculation : *9* (regarding various performances)
take-off speed : 101.2 [km/u]
static prop wash : 96 [km/u]
take-off distance at sea-level : 213 [m]
lift/drag ratio : 12.09 [ ]
climb to 1000m with max payload : 6.65 [min]
climb to 2000m with max payload : 13.28 [min]
climb to 3000m with max payload : 20.93 [min]
published ceiling (4000 [m]
practical ceiling (operational weight) : 7078 [m] with flying weight :1383 [kg] line 3385
practical ceiling fully loaded (mtow- 30 min.fuel) : 5803 [m] with flying weight :1710 [kg]
max. dive speed : 472.5 [km/hr] at 4803 [m] height
turning speed at CLmax : 112.1 [km/u] at 50 [m] height
turn radius at 50m: 51 [m]
time needed for 360* turn 10.2 [seconds] at 50m
load factor at max. angle turn 2.20 ["g"]
calculation *10* (action radius & endurance)
published range : 560 [km] with 2 crew and 261.5 [kg] useful load and 88.1 [%] fuel
dit bereik is niet mogelijk met alle pax > nakijken, evt bereik verlagen
range : 253 [km] with 2 crew and 340.0 [kg] useful load and 39.8 [%] fuel
range : 18 [km] with 4.0 passengers with luggage and 2.9 [%] fuel
Available Seat Kilometers (ASK) : 74 [paskm]
max range theoretically with additional fuel tanks for total 662.6 [litre] fuel : 1899.3 [km]
useful load with range 500km : 358 [kg]
useful load with range 500km : 3 passengers
production (useful load): 57.00 [tonkm/hour]
production (passengers): 637.20 [paskm/hour]
short range airliner line 3734!!
oil and fuel consumption per tonkm : 0.78 [kg]
oil and fuel consumption per paskm : 0.07 [kg]
fuel cost per paskm : 0.07 [eur]
writing off per paskm : 0.27 [eur]
insurance per paskm : 0.01 [eur]
crew cost per paskm : 0.24 [eur]
maintenance cost per paskm : 0.14 [eur]
direct operating cost per paskm : 0.73 [eur]
°
Fatal accidents :
01 September 1920 Junkers-Larsen JL-6 caught fire and crashed in Morristown, NJ, USA. Pilot Max miller and his mechanic Gustav Rierson died.
18 Februari 1921 F 13 reg.D 128 crashed near Lauenburg (East Prusia, now Lebork in Poland) en route to Stuttgart. Fog and snow conditions led to CFIT. Pilot Emil Monz and passenger Oskar Kretschmar died in the crash.
08 June 1924 F 13 from SCADTA reg. A13 stalled and crashed into a tree on take-off from Barranquilla, Colombia. All 5 on board died.
22 March 1925 F 13 R-RECA from Zakavia crashed on TO at Tiflis, Georgia. All 5 on board died including 3 high-ranking soviet officials
24 July 1926 F 13 from Luft Hansa, reg D-272 crashed at Juist, Germany in bad weather. All 4 on board died.
27 July 1927 F 13 Luft Hansa reg. D-206 crashed near Amoneburg, Germany after PUF. All 5 on board died
26 May 1928 F 13 Luft Hansa reg. D-583, crashed near Hahnenberg, Radevormwald, Germany due to pilot error. 3 died
21 July 1930 F 13 Walcot airline G-AAZK crashed at Meopham, Gravesend, Kent, GB due to structural failure. All 6 on board died. Pilot Lt.Col. George L.P. Henderson
12 July 1932 J 13 D-1608 crashed after TO in heavy fog, at Otrokovice-Bahnak, Czech republic 2 died pilot : Broucek, Jindrich
02 November 1932 Lufthansa D-724 crashed at Echterpfuhl, Germany, wing failure, 5 death
09 October 1935 Aero/OY F 13 reg. OH-ALI crashed into Gulf of Finland in fog, 6 death
Literature :
Praktisch handbook vliegtuigen deel 2 page 188,119
Junkerspilot Emil Monz tödlich verunglückt - Junkers
Piston-engiend airliners page 11
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 05 February 2021 contact : info.aircraftinvestigation@gmail.com python 3.7.4