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weight and performance calculations for the Fokker F.II
Fokker F.II
role : light passenger aircraft
importance : ***
first flight : V.45 prototype oktober 1919, flown by Adolf Parge at Schwerin, Germany
operational : 30 September 1920
design : Reinhold Platz
production : ca. 3? at Schwerin (Gorries) , 19 license built in Berlin-Staaken by Grulich and 4? by Fokker in Veere
general information :
On 30 September 1920 the KLM made the first passenger flight from Schiphol to the UK (Croydon) with the F.II H-NABD. It was piloted by one-eyed W.G.R. Hinchcliffe and aboard as passenger were Bernard de Waal , mechanician Simon Elleman , Albert Plesman , founder of the KLM and journalist Henri Hegener . The distance from Schiphol to Croydon of 350km was flown in 3 hours. KLM had bought two, the H-NABC and the H-NADB for 45000 guilders total. They flew with it to London and Hamburg. The prototype of the F.II, built in Schwerin and referred to as V.45, flew for the first time in Germany and was flown clandestine to the Netherlands with some difficulty by Bernhard de Waal on March 20, 1920. It had problems with the carburetor and De Waal had to make a third ! emergency landing near Surhuisterveen , this time the landing gear collapsed. Anthony Fokker hurried to Friesland, and saw the F.II this day for the first time ! The aircraft was taken apart and carried by train to Leeuwarden, after which the aircraft was carried on a barge over the water to Amsterdam. On 17 May 1920 Fokker demonstrated the F.II to the KLM and the press. The KLM, led by Albert Plesman ordered two F.II’s for the price of 45.000 Dutch guilders which were built in Schwerin. This aircraft had a 185hp BMW IIIa engine (136 KW). KLM later replaced this engine with a 240hp Armstrong-Siddeley Puma engine (176KW), recognizable by the "stove pipe" exhaust on the bonnet. The pilot was seated in the open air in front of the passenger cabin below the thick cantilever wing.
Fokker had moved a big part of the inventory of the Schwerin factory (Gorries) , including partly completed aircraft and engines on 6 long trains to the Netherlands shortly after the war. He left Rheinhold Platz in charge of the remaining of the Fokker Factories in Germany and he started to design civil aircraft, including the F.II. Some F.II’s were built at Schwerin. In 1921 Platz and his staff moved to Veere, Zeeland the Netherlands and production of the F.II continued here. But only a few F.II’s were built in Veere, soon production switched to the F.III.
About 19 F.II aircraft were license built by Deutscher Aero Lloyd under supervision of dr.ing. Karl Grulich in Berlijn-Staaken, powered by a 250hp BMV IV engine and were referred to as Fokker-Grulich F.2a or F.2b. The wings were made by Albatros. The Deutsche Luft Hansa started flying with those Grulich built F.II’s in 1926.
The D-57 prototype was later sold to the Rijksstudiedienst voor de Luchtvaart in Amsterdam, what later would become the Nationaal Lucht-en Ruimtevaart Laboratorium (NLR). They used it under the registration PH-RSL as flying laboratorium. It was destroyed in a bomb-raid by the Luftwaffe in a hangar at Schiphol at 10 May 1940.
The KLM suspended the air service in the winter 1920/1921. On 14 April 1921 the service was resumed but now with the bigger F.III, so the F.II only had a short service live with the KLM on the regular flights.
During the winter of 1920/1921 all KLM flights were suspended. On 14 April 1921 scheduled passenger flights were resumed but now with the new bigger Fokker F.III.
KLM from now used the F.II aircraft as a photo plane, charter and for round-trip flights until 1927. The F.II's direct competitor was the Junkers F.13. The F.II was slightly heavier and 35 km/h slower. KLM sold its F.II's on 15 September 1927 to the Sabena, which flew with them until 1936.
Construction : Wooden wing covered with plywood, fuselage of welded steel tubes covered with
linen.
crew : 1 passengers : 4
Users : KLM (2), Sabena(2), Deutsche Luftrederei(19),later Lufthansa, NLR(1), Balair (Swiss), DDL (Denmark) and ATA (Italy), Deutscher Aero Lloyd.
registrations : KLM H-NABC, H-NABD, D-57 (prototype later PH-RSL), O-BAIB, O-BAIC, Lufthansa : D756, D717, D728, D587, D783, D785, D765 “Eider”, D766, D-767
engine : 1 Armstrong Siddeley Puma liquid-cooled 6-cylinder inline engine 240 [hp](179.0 KW)
dimensions :
wingspan : 17.24 [m], length : 11.55 [m], height : 3.6[m]
wing area : 38.2 [m^2]
weights :
max.take-off weight : 1894 [kg]
empty weight operational : 1193 [kg] useful load : 400 [kg]
performance :
maximum speed :150 [km/hr] at sea-level
cruise speed :135 [km/u] op 100 [m]
service ceiling : 4880 [m]
range : 720 [km]
description :
parasol wing with fixed landing gear and tail strut
two spar wing
engines, landing gear attached to the fuselage, luggage compartment in the rear of the fuselage
airscrew :
fixed pitch 2 -bladed tractor airscrew with max. efficiency :0.65 [ ]
estimated diameter airscrew 3.17 [m]
angle of attack prop : 13.68 [ ]
fine pitch
reduction : 1.00 [ ]
airscrew revs : 1650 [r.p.m.]
pitch at Max speed 1.52 [m]
blade-tip speed at Vmax and max revs. : 232 [m/s]
calculation : *1* (dimensions)
measured wing chord : 2.30 [m]
mean wing chord : 2.22 [m]
calculated wing chord (rounded tips): 2.49 [m]
wing aspect ratio : 7.78 []
seize (span*length*height) : 717 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 3.6 [kg/hr]
fuel consumption(cruise speed) : 38.0 [kg/hr] (51.9 [litre/hr]) at 62 [%] power
distance flown for 1 kg fuel : 3.55 [km/kg] at 2440 [m] cruise height, sfc : 342.2 [kg/kwh]
estimated total fuel capacity : 313.88 [litre] (230.07 [kg])
calculation : *3* (weight)
weight engine(s) dry : 286.0 [kg] = 1.60 [kg/KW]
weight 30.0 litre oil tank : 2.55 [kg]
oil tank filled with 1.3 litre oil : 1.2 [kg]
oil in engine 10.0 litre oil : 8.9 [kg]
fuel in engine 1.2 litre fuel : 0.89 [kg]
weight 22.0 litre gravity patrol tank(s) : 3.3 [kg]
weight radiator : 25.6 [kg]
weight exhaust pipes & fuel lines 22.1 [kg]
weight self-starter : 4.4 [kg]
weight cowling 7.2 [kg]
weight airscrew(s) (wood) incl. boss & bolts : 74.5 [kg]
total weight propulsion system : 434 [kg](22.9 [%])
***************************************************************
fuselage skeleton (wood gauge : 7.50 [cm]): 166 [kg]
fuselage width : 1.41 [m]
cabin layout : pitch : 87 [cm] (1+1) seating in 2.0 rows
passenger cabin area : 2.19 [m2]
weight 4.0 windows : 3.60 [kg]
passenger cabin width : 1.26 [m] cabin length : 1.74 [m] cabin height : 1.90 [m]
cabin space : 4.17 [m3]
weight cabin furbishing : 19.60 [kg]
bracing : 13.5 [kg]
fuselage covering ( 25.2 [m2] doped linen fabric) : 7.9 [kg]
weight instruments. : 2.5 [kg]
weight lighting : 1.1 [kg]
weight controls : 6.3 [kg]
weight seats : 25.0 [kg]
weight 292 [litre] main fuel tank empty : 23.3 [kg]
weight air conditioning : 6 [kg]
weight engine mounts & firewalls : 9 [kg]
total weight fuselage : 284 [kg](15.0 [%])
***************************************************************
weight wing covering (plywood) : 32 [kg]
total weight ribs (70 ribs) : 113 [kg]
load on front upper spar (clmax) per running metre : 605.1 [N]
load on rear upper spar (vmax) per running metre : 297.3 [N]
total weight 4 spars : 103 [kg]
weight wings : 247 [kg]
weight wing/square meter : 6.48 [kg]
weight cables (69 [m]) : 59.2 [kg] (= 859 [gram] per metre)
diameter cable : 11.8 [mm]
weight fin & rudder (3.4 [m2]) : 22.9 [kg]
weight stabilizer & elevator (4.3 [m2]): 28.1 [kg]
total weight wing surfaces & bracing : 358 [kg] (18.9 [%])
*******************************************************************
wheel pressure : 947.0 [kg]
weight 2 wheels (850 [mm] by 131 [mm]) : 49.7 [kg]
weight tailskid : 3.3 [kg]
weight undercarriage with axle 30.1 [kg]
total weight landing gear : 83.1 [kg] (4.4 [%]
*******************************************************************
Note the exhaust pipes of the Puma engine.
********************************************************************
calculated empty weight : 1159 [kg](61.2 [%])
weight oil for 6.4 hours flying : 22.9 [kg]
weight cooling fluids : 38.7 [kg]
calculated operational weight empty : 1221 [kg] (64.5 [%])
published operational weight empty : 1193 [kg] (63.0 [%])
***o***
"
weight crew : 81 [kg]
weight fuel for 2.0 hours flying : 76 [kg]
********************************************************************
operational weight empty: 1378 [kg](72.7 [%])
weight 4 passengers : 308 [kg]
weight luggage & freight : 92 [kg]
operational weight loaded: 1778 [kg](72.7 [%])
fuel reserve : 116.2 [kg] enough for 3.06 [hours] flying
operational weight fully loaded : 1894 [kg] with fuel tank filled for 84 [%]
published maximum take-off weight : 1894 [kg] (100.0 [%])
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calculation : * 4 * (engine power)
power loading (Take-off) : 10.58 [kg/kW]
The Lufthansa F.II’s had a bigger windscreen
power loading (operational without useful load) : 7.70 [kg/kW]
total power : 179.0 [kW] at 1650 [r.p.m]
calculation : *5* (loads)
manoeuvre load : 2.0 [g] at 1000 [m]
limit load : 3.0 [g] ultimate load : 4.5 [g] load factor : 1.5 [g]
design flight time : 3.73 [hours]
design cycles : 228 sorties, design hours : 850 [hours]
operational wing loading : 354 [N/m^2]
wing stress (3 g) during operation : 164 [N/kg] at 3g emergency manoeuvre
calculation : *6* (angles of attack)
angle of attack zero lift : -1.18 ["]
max. angle of attack (stalling angle) : 12.32 ["]
angle of attack at max. speed : 2.77 ["]
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 : 0.34 [ ]
induced drag coefficient at max. speed : 0.0062 [ ]
drag coefficient at max. speed : 0.0679 [ ]
drag coefficient (zero lift) : 0.0617 [ ]
calculation : *8* (speeds
stalling speed at sea-level (OW): 81 [km/u]
stalling speed at sea-level (MTOW): 95 [km/u]
landing speed at sea-level: 95 [km/hr]
min. drag speed (max endurance) at cruise height : 100 [km/hr] at 2440 [m] (power:42 [%])
min. power speed (max range) : 100 [km/hr] at 2440 [m] (power:42 [%])
max. rate of climb speed : 91.1 [km/hr] at sea-level
cruising speed : 135 [km/hr] op 2440 [m] (power:64 [%])
design speed prop : 142 [km/hr]
maximum speed : 150 [km/hr] op 100 [m] (power:99 [%])
climbing speed at sea-level : 268 [m/min]
calculation : *9* (regarding various performances)
take-off speed : 113.6 [km/u]
emergency/TO power : 250 [hp] at 1760 [rpm]
static prop wash : 130 [km/u]
take-off distance at sea-level : 183 [m]
lift/drag ratio : 8.62 [ ]
climb to 1000m with max payload : 8.68 [min]
climb to 2000m with max payload : 23.89 [min]
climb to 3000m with max payload : 53.28 [min]
published ceiling (4880 [m]
practical ceiling (operational weight) : 4898 [m] with flying weight :1378 [kg] line 3385
practical ceiling fully loaded (mtow- 30 min.fuel) : 3163 [m] with flying weight :1875 [kg]
max. dive speed : 312.0 [km/hr] at 2163 [m] height
turning speed at CLmax : 118.8 [km/u] at 50 [m] height
turn radius at 50m: 58 [m]
time needed for 360* turn 11.1 [seconds] at 50m
load factor at max. angle turn 2.15 ["g"]
calculation *10* (action radius & endurance)
published range : 720 [km] with 1 crew and 389.6 [kg] useful load and 88.1 [%] fuel
range : 683 [km] with 1 crew and 400.0 [kg] useful load and 83.6 [%] fuel
max range theoretically with additional fuel tanks for total 808.0 [litre] fuel : 2103.6 [km]
useful load with range 500km : 451 [kg]
production : 60.95 [tonkm/hour]
oil and fuel consumption per tonkm : 0.68 [kg]
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Fatal crashes :
22 July 1929 Fokker-Grulich F.II D-780 “Havel” s/n 1572 piloted by Hans Loeb . Engine failure shortly after TO from Berlin-Tempelhof. Pilot lost control and aircraft crashed near the runway. Pilot was killed
24 August 1929 Fokker-Grulich F.II D-757 s/n 1571 piloted by Alfred Bauer
After passing Schlüchtern, Hesse, pilot followed the railway to the northeast when he encountered poor visibility due to foggy conditions. Between Elm and Hutten, aircraft hit a hilly terrain and was destroyed. The pilot and three passengers were killed while a fourth passenger was seriously injured.
Fokker-Grulich D-587 “Neckar” s/n 1569 of DLH, after this crash it was repaired ! and flew again as D-OVAL. The Fokker-Grulich aircraft had BMW engines and a bigger windscreen for the pilot.
Literature :
Fokker verkeersvliegtuigen 1920-1940 page 6,10,11,12,13,14, 78
Praktisch handboek vliegtuigen deel II page 196
Fokker – bouwer aan de wereldluchtvaart page 49
www.dutch-aviation.nl/index5/Civil/index5-2 F2.html (dutch-aviation.nl)
Piston-engined airliners page 11, 12
Vermetele vliegende Hollanders page 27
Alles over de Fokker Friendship page 13,14,15
Fokker-Grulich F.II | It AvOliT (jmgrisnich.nl)
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 01 January 2021 contact : info.aircraftinvestigation@gmail.com python 3.7.4
