weight and performance calculations for the Fokker F.VIIa/3m
Fokker F.VIIa/3m
role : multi-engined passenger aircraft
importance : ****
first flight : 04 September 1925 by Anthony Fokker operational : October 1925
country : The Netherlands
design : F.VIIa adaption by Reinhold Platz
production : 18 aircraft
general information :
Walter Rethel returned to Germany (to Arado) and Reinhold Platz took over his work
in Amsterdam.
The second F.VIIa built, was adapted by adding two engines under the wing. Platz made already drawings for a 3-engined variant of the F.VII in June 1925, this was before Henry Ford announced is reliability tour in July 1925. Fokker didn’t like the idee of the 3-engined variant, possibly this is why the single-engined F.VIIa prototype c/n 4899 was shipped with the S.S.Veendam to the US on 7 September 1925 together with the first F.VIIa-3m !
The aircraft arrived on 21 September 1921 in the US and were assembled at Hasbrouck Heights (New York). . The single engine F.VIIa made a forced landing on 26 September on its way to Detroit after an engine failure, while the F.VIIa-3m won the Reliability Tour ! The Ford Commercial airplane Reliability Tour was not about speed, but by arriving everyday as the first aircraft at its destination the Fokker 3-motor draw a lot of attention from the press. The Reliability tour started in Detroit on 28 September 1925. The F.VIIa/3m was flown by Anthony Fokker together with E.P.Lott and Robert Noorduyn .
The Fokker could stay in the air with only one engine running.
After the tour the F.VIIa-3m was sold to Edsel Ford, the son of Henry Ford. He gave it the name Josephine Ford , after his youngest daughter and donated the aircraft to Lt.Cdr. Richard E. Byrd . On 6 May 1926 Byrd flew together with Floyd Bennet from Spitsbergen to the North pole and back. Registration : NC267 c/n 600
This Fokker aircraft is still preserved and can be seen in The Henry Ford Museum in Dearborn, Michigan.
Low operating cost 0.65 [eur/paskm] > this was due to the reliable Whirlwind engines that need less maintenance > calculated TBO 66 hours. The radial engines gave a good ratio between empty and max TOW > 59.7%
At MTOW of 3900 kgs it had a high wing loading !
Three aircraft were delivered to the Dutch air force (LVA) for transport, bombing, photography and crew training (reg. 801,802,803). One of those, first made a flight to the Dutch East -India (Indonesia), with registration H-NAEA and named “Postduif” (mail pigeon). It had 220hp Gnome-Rhone Titan engines. Lt-flyer G.A. Koppen , KLM-pilot G.M.H Frijns and mechanic S.Elleman took off on 01 October 1927 and arriving in Batavia ten days later. 13.360 km in 9 flying days > average 1514 km = 8 hours 25 min. flying everyday = 180 km/hr. Back to Schiphol they flew the distance in 12 days. It had additional fuel tanks, making total fuel capacity 1300 litre.
The KLM did not use the FVIIa/3m for passenger flights, they continued with the single-engine FVIIa. Later they used the FVIIb/3m from 1928 on.
users : Lt.cdr.Byrd, LVA, Philadelphia Rapid Transit Company (3), Panam (3 C-2)
crew : 2 passengers : 8
engine : 3 Wright R-790 J-4 Whirlwind air-cooled 9 -cylinder radial engine 220 [hp]
(164.1 KW) without supercharger
dimensions :
wingspan : 19.3 [m], length : 14.6 [m], height : 3.89[m]
wing area : 58.5 [m^2]
weights :
max.take-off weight : 3900 [kg]
empty weight operational : 2300 [kg] useful load : 800 [kg]
performance :
maximum speed :197 [km/hr] at sea-level
cruise speed :177 [km/u] op 100 [m]
service ceiling : 4750 [m]
range : 1000 [km]
description :
parasol wing with fixed landing gear and tail strut
two spar wing
2 engines attached to the wings 1 in the nose, landing gear attached to the wings, useful load in the fuselage
fuel tanks in the wing centre section
airscrew :
three fixed pitch 2 -bladed tractor airscrews with max. efficiency :0.66 [ ]
estimated diameter airscrew 2.68 [m]
angle of attack prop : 14.57 [ ]
fine pitch
reduction : 1.00 [ ]
airscrew revs : 2000 [r.p.m.]
pitch at Max speed 1.64 [m]
blade-tip speed at Vmax and max revs. : 286 [m/s]
calculation : *1* (dimensions)
measured wing chord : 3.04 [m]
mean wing chord : 3.03 [m]
calculated average wing chord tapered wing with rounded tips: 3.04 [m]
wing aspect ratio : 6.37 []
seize (span*length*height) : 1096 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 8.9 [kg/hr]
fuel consumption(cruise speed) : 103.3 [kg/hr] (140.9 [litre/hr]) at 65 [%] power
distance flown for 1 kg fuel : 1.72 [km/kg] at 2375 [m] cruise height, sfc : 324.8 [kg/kwh]
estimated total fuel capacity : 902 [litre] (661 [kg])
calculation : *3* (weight)
weight engine(s) dry : 708.0 [kg] = 1.44 [kg/KW]
weight 79.1 litre oil tank : 6.72 [kg]
oil tank filled with 3.7 litre oil : 3.3 [kg]
oil in engine 2.7 litre oil : 2.5 [kg]
fuel in engine 3.4 litre fuel : 2.46 [kg]
weight 59.9 litre gravity patrol tank(s) : 9.0 [kg]
weight self-starter : 4.0 [kg]
weight cowling 6.6 [kg]
weight airscrew(s) (wood) incl. boss & bolts : 55.8 [kg]
total weight propulsion system : 792 [kg](20.3 [%])
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fuselage skeleton (steel tubes) : 5.93 [cm]): 405 [kg]
cabin layout : pitch : 87 [cm] (1+1) seating in 4.0 rows
weight toilet : 5 [kg]
weight 8.0 windows : 7.20 [kg]
passenger cabin width : 1.68 [m] cabin length : 3.48 [m] cabin height : 1.90 [m]
weight cabin furbishing : 25.56 [kg]
weight cabin floor : 37.43 [kg]
bracing : 41.7 [kg]
fuselage covering ( 40.3 [m2] doped linen fabric) : 12.5 [kg]
Span : 63 ft 4 in = 19.30m length 49 ft 2 in = 14.99m height 12 ft 9 in = 3.89m
weight radio navigation equipment : 7.0 [kg]
weight instruments. : 4.0 [kg]
weight lighting : 2.0 [kg]
weight dual controls + indicators: 27.1 [kg]
weight seats : 50.0 [kg]
weight three 281 [litre] main fuel tanks empty : 67.4 [kg]
weight air conditioning : 12 [kg]
weight fuel lines : 5 [kg]
weight engine mount and firewall : 8 [kg]
total weight fuselage : 716 [kg](18.4 [%])
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weight plywood wing covering : 61 [kg]
total weight ribs (70 ribs) : 232 [kg]
weight engine mounts : 16 [kg]
load on front upper spar (clmax) per running metre : 1011.1 [N]
load on rear upper spar (vmax) per running metre : 531.3 [N]
total weight 4 spars : 181 [kg]
weight wings : 474 [kg]
weight wing/square meter : 8.11 [kg]
cantilever wing without bracing cables
weight fin & rudder (4.3 [m2]) : 35.7 [kg]
weight stabilizer & elevator (6.6 [m2]): 53.8 [kg]
total weight wing surfaces & bracing : 580 [kg] (14.9 [%])
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wheel pressure : 1950.0 [kg] > high wheel pressure !
weight 2 wheels (1050 [mm] by 162 [mm]) : 103.4 [kg]
weight tailskid : 6.4 [kg]
weight undercarriage with axle 70.2 [kg]
total weight landing gear : 180.0 [kg] (4.6 [%]
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calculated empty weight : 2268 [kg](58.2 [%])
weight oil for 6.8 hours flying : 60.0 [kg]
calculated operational weight empty : 2328 [kg] (59.7 [%])
published operational weight empty : 2300 [kg] (59.0 [%])
weight crew : 162 [kg]
weight fuel for 2.0 hours flying : 207 [kg]
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operational weight empty: 2696 [kg] (69.1 [%])
weight 8 passengers : 616 [kg]
weight luggage & freight : 184 [kg]
operational weight loaded: 3496 [kg](69.1 [%])
fuel reserve : 403.6 [kg] enough for 3.91 [hours] flying
operational weight fully loaded : 3900 [kg] with fuel tank filled for 92 [%]
published maximum take-off weight : 3900 [kg] (100.0 [%])
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calculation : * 4 * (engine power)
power loading (Take-off) : 7.92 [kg/kW]
power loading (operational without useful load) : 5.48 [kg/kW]
power loading (Take-off) 1 PUF: 11.89 [kg/kW]
total power : 492.2 [kW] at 2000 [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 : 1.4 [g]
design flight time : 3.95 [hours]
design cycles : 2180 sorties, design hours : 8605 [hours]
operational wing loading : 452 [N/m^2]
wing stress (3 g) during operation : 167 [N/kg] at 3g emergency manoeuvre
calculation : *6* (angles of attack)
angle of attack zero lift : -2.11 ["]
max. angle of attack (stalling angle) : 12.02 ["]
angle of attack at max. speed : 0.98 ["]
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 : 0.25 [ ]
induced drag coefficient at max. speed : 0.0041 [ ]
drag coefficient at max. speed : 0.0553 [ ]
drag coefficient (zero lift) : 0.0512 [ ]
With the Fokker F.VII/3m (Military C-2) America NX206 c/n 703 Commander Byrd flew together with Bert Acosta and Bernt Balchen over the Atlantic ocean from New York to Paris on 29-30 June 1927. They flew for 40 hours in bad weather, could not find Le Bourget due to fog, returned to the coast and ditched in the sea near Ver-sur-mer . For the long distance flight an additional fuel tank was installed in the fuselage good for 3000 litre petrol giving a non-stop range of ca. 6000 km. Bert Acosta could not fly on instruments so Bernt Balchen did most of the flying as the weather was bad most of the time during the flight.
Bernt Balchen was hired as test pilot by Anthony Fokker in 1926 for the Fokker Aircraft Company at Teterboro airport, New Jersey
calculation : *8* (speeds
stalling speed at sea-level (OW loaded : 3797 [kg]): 109 [km/u]
landing speed at sea-level: 128 [km/hr]
min. drag speed (max endurance) : 139 [km/hr] at 2375 [m](power :52 [%])
min. power speed (max range) : 139 [km/hr] at 2375 [m] (power:52 [%])
max. rate of climb speed : 117.7 [km/hr] at sea-level
cruising speed : 177 [km/hr] op 2375 [m] (power:73 [%])
design speed prop : 187 [km/hr]
maximum speed : 197 [km/hr] op 100 [m] (power:106 [%])
climbing speed at sea-level : 404 [m/min]
calculation : *9* (regarding various performances)
take-off speed : 132.3 [km/u]
static prop wash : 152 [km/u]
take-off distance at sea-level : 169 [m]
lift/drag ratio : 8.56 [ ]
H-NAEA “Postduif” c/n 5006 flew to Indonesia October 1927. Later it flew with the LVA with registration 803
climb to 1000m with max payload : 5.80 [min]
climb to 2000m with max payload : 14.76 [min]
climb to 3000m with max payload : 28.47 [min]
published ceiling (4750 [m]
practical ceiling (operational weight) : 5883 [m] with flying weight :2696 [kg]
practical ceiling fully loaded (mtow- 30 min.fuel) : 3818 [m] with flying weight :3848 [kg]
max. dive speed : 445.1 [km/hr] at 2818 [m] height
turning speed at CLmax : 142.9 [km/u] at 50 [m] height
turn radius at 50m: 73 [m]
time needed for 360* turn 11.6 [seconds] at 50m
load factor at max. angle turn 2.42 ["g"]
calculation *10* (action radius & endurance)
published range : 1000 [km] with 2 crew and 827.6 [kg] useful load and 88.1 [%] fuel
range : 1047 [km] with 2 crew and 800.0 [kg] useful load and 92.3 [%] fuel
range : 1226 [km] with 8.0 passengers with each 10 [kg] luggage and 108.0 [%] fuel
Available Seat Kilometers (ASK) : 9807 [paskm]
max range theoretically with additional fuel tanks for total 2034.3 [litre] fuel : 2559.8 [km]
useful load with range 500km : 1200 [kg]
useful load with range 500km : 8 passengers
F.VIIa/3m c/n 5006 of the Dutch air force (LVA)
production (useful load): 212.73 [tonkm/hour]
production (passengers): 1418.40 [paskm/hour]
oil and fuel consumption per tonkm : 0.53 [kg]
oil and fuel consumption per paskm : 0.08 [kg]
fuel cost per paskm : 0.08 [eur]
crew cost per paskm : 0.11 [eur]
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time between engine failure : 330 [hr]
low risk for emergency landing, can continue flying with 1 engine out
writing off per paskm : 0.14 [eur]
insurance per paskm : 0.0128 [eur]
maintenance cost per paskm : 0.3164 [eur]
direct operating cost per paskm : 0.65 [eur]
serious accidents :
Cabin layout of G-EBYI ,the private owned F.VIIa/3m of Alfred Loewenstein.
Literature:
Piston-engined airliners page 13,15
Alles over de Fokker Friendship page 31-38, 116,122
Praktisch handboek vliegtuigen deel 2 page 200,201
Fokker verkeersvliegtuigen page 50-55
Fokker – bouwer aan de wereldluchtvaart page 70, 75
Van Spin tot Fokker 100 page 19,23,29
Fokker verkeersvliegtuigen 1920-1940 page 29,78
Microsoft Word - Document8 (panam.org)
Fokkers “Roaring twenties”page 25
De Nederlandse vliegtuigen page 42,44,47
Wright J-4 Whirlwind Archives - This Day in Aviation
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 16 March 2021 contact : info.aircraftinvestigation@gmail.com python 3.7.4