Fokker F.VIIa | aircraft investigation

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weight and performance calculations for the Fokker F.VIIa

110 ideeën over Fokker F-VII in 2021 | luchtvaart, vliegtuig, vintage reisposters

F.VIIa H-NACT s/n 4901 with simplified landing gear designed by Ir.Bertus Grasé, rounded wingtips and radial engine. It was the first F.VIIa to fly for the KLM. After many years flying passengers,H-NACT was eventually destroyed at Schiphol 10 May 1940 during the German invasion.

Fokker F.VIIa

role : medium weight passenger aircraft

importance : ****

first flight : 12 March 1925 N-NACZ flown by Ir.Bertus Grasé

operational : June 1925

country : The Netherlands

design : Walter Rethel / Bertus Grasé

production : 62 aircraft (42 by Fokker, 4 by KLM, 16 in the USA), more built under license.

general information :

Ingenieur Bertus Grasé refined the F.VII design, the ailerons were integrated in the wing, the landing gear was simplified and streamlined.

The prototype was flown with a 420 hp Packard Liberty liquid cooled engine, in the following aircraft this was replaced by a more reliable air-cooled Bristol Jupiter engine.

The engine mounting in the nose was specially designed to take different kind of engines, this gave customers liberty to take the engine they preferred.

It was the first passenger aircraft in service with a air cooled radial engine.

Ir.Bertus Grasé attempted to set a new record for height with 1000 kg useful load on 30 April 1925. He reached 5771m, this was to small margin above the record set by a Farman Goliath > 5751m.

But he set a record for endurance to fly for 3 hrs 3 minutes and 30 seconds with a useful load of 1500 kg

The KLM F.VIIa’s made 16 emergency landings in 1927 due to engine failure, 10 in 1928 and only 3 in 1929. It looks as the Jupiter engine was not so reliable in the first service years...In 1927 two F.VIIa’s with Jupiter engine were used for long-distance transatlantic flight with fatale results. Flying on one engine over the vast ocean was very hazardous.

Metal Curtiss-Reed propellor. Fuel : 720 litre

F.VIIa H-NADP was chartered by American millionaire Van Lear Black for a flight to

Indonesia. The trip of 13.110 km was flown by Geysendorffer, Scholte and Weber

with Van Lear Black as passenger between 15 June and 23 July 1927. It had

extended range tanks good for a range of 2010 km.

The F.VIIa was more fuel efficient then the F.VIIa/3m

fuel consumption(cruise speed) : 77.2 [kg/hr] (105.4 [litre/hr])

distance flown for 1 kg fuel : 2.21 [km/kg] [kg/kwh]

oil and fuel consumption per tonkm : 0.42 [kg]

compared to F.VIIa/3m :

fuel consumption(cruise speed) : 103.3 [kg/hr] (140.9 [litre/hr])

distance flown for 1 kg fuel : 1.72 [km/kg]

oil and fuel consumption per tonkm : 0.53 [kg]

The F.VIIa carried the same number of passenger at the same cruise speed. For this reason the single engined F.VIIa was kept in service being a good aircraft, the F.VIIa/3m with 3 engines could be used more safe for flights over water and in the mountains with the higher ceiling it had and de safety of 3 engines.

Later H-NADP was converted to a 3-engined F.VIIa/3m

users : KLM (15), Swissair, Air France, LOT, CLS, DDL

F.VIIa pilots :, J.J.Hondong , W.M.O.A.Beekman , Evert Van Dijk , J.J.E. Duimelaar , L.Sillevis , G.J. Geysendorffer , I.A.Aler , G.M.H Frijns , Quirinus Tepas , , Piet Soer , J.B.Scholte , E.C.Pellens , W.C. van Veenendaal , R.H.McIntosh , J.C.Fitzmaurice , Bert Hinkler , C.D.Barnard , Eric Herbert Alliott, Robert (Bob) Little

crew : 2 passengers : 8

engine : 1 Bristol Jupiter VI air-cooled 9 -cylinder radial engine 440 [hp](328.1 KW)

without supercharger

dimensions :

wingspan : 19.3 [m], length : 14.6 [m], height : 3.9[m]

wing area : 58.5 [m^2]

weights :

max.take-off weight : 3500 [kg]

empty weight operational : 1950 [kg] useful load : 800 [kg]

performance :

maximum speed :190 [km/hr] at sea-level

cruise speed :171 [km/u] op 100 [m]

service ceiling : 2900 [m]

range : 1029 [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 :0.66 [ ]

estimated diameter airscrew 3.46 [m]

angle of attack prop : 15.33 [ ]

reduction : 1.00 [ ]

airscrew revs : 1700 [r.p.m.]

pitch at Max speed 1.86 [m]

blade-tip speed at Vmax and max revs. : 262 [m/s]

The F.VIIa prototype c/n 4899 was registered in the Netherlands on 21 August 1925 as H-NACZ. On 7 September 1925 it was shipped to the US aboard S.S.Veendam together with the first F.VIIa/3m to take part in the Ford Commercial airplane Reliability Tour . After arriving in New York on 21 September 1925 it was assembled at Hasbrouck Heights (New York). Fokker demonstrated the aircraft to the public on Mineola airfield , Long Island, with the Ziegfeld Girls as part of the show. However the aircraft did not participate in the reliability tour because it made a crash landing in the Allegheny mountains after an engine failure flying over Pennsylvania on its way to Detroit (ca. 26 Sep. 1925 ), it had a Liberty liquid cooled engine as can be seen in this picture. It was sold to G.H.Wilkins , was baptised “Alaskan” and used for an arctic expedition.

videos – Sir Hubert Wilkins

“Alaskan” c/n 4899 was taken by ship to Alaska medio 1926 together with the F.VII/3m “Detroiter”.

wilkins-1926-alaskan-1

The wheels replaced by ski’s. The goal of the expedition was to fly to the North pole, but this did not happen due to a bad landing in Alaska on 25 February 1927, which broke the wing of the “Alaskan”. The “Detroiter” also made a bad landing and broke its landing gear. The broken wing of the “Alaskan” was left behind in Alaska but the fuselage was taken to Seattle and is now conserved in the Fargo Air Museum , North Dakota. (according “World directory of airline crashes” page 14 c/n was 4909 !?)

calculation : *1* (dimensions)

measured wing chord : 3.30 [m]

mean wing chord : 3.03 [m]

calculated wing chord (rounded tips): 3.43 [m]

wing aspect ratio : 6.37 []

seize (span*length*height) : 1099 [m^3]

calculation : *2* (fuel consumption)

oil consumption : 8.2 [kg/hr]

fuel consumption(cruise speed) : 77.2 [kg/hr] (105.4 [litre/hr]) at 74 [%] power

distance flown for 1 kg fuel : 2.21 [km/kg] at 1450 [m] cruise height, sfc : 316.2 [kg/kwh]

estimated total fuel capacity : 719.75 [litre] (527.58 [kg])

calculation : *3* (weight)

weight engine(s) dry : 354.0 [kg] = 1.08 [kg/KW]

weight 74.2 litre oil tank : 6.31 [kg]

oil tank filled with 2.5 litre oil : 2.2 [kg]

oil in engine 1.8 litre oil : 1.6 [kg]

fuel in engine 2.2 litre fuel : 1.64 [kg]

weight 44.8 litre gravity patrol tank(s) : 6.7 [kg]

weight self-starter : 8.0 [kg]

weight cowling 13.1 [kg]

weight airscrew(s) (wood) incl. boss & bolts : 133.2 [kg]

total weight propulsion system : 521 [kg](14.9 [%])

***************************************************************

fuselage skeleton (steel tubes) : 5.89 [cm]): 399 [kg]

cabin layout : pitch : 87 [cm] (1+1) seating in 4.0 rows

weight toilet : 5 [kg]

Fokker F.VII, scale | Aviation, RC models and aircraft

weight 8.0 windows : 7.20 [kg]

passenger cabin width : 1.70 [m] cabin length : 3.48 [m] cabin height : 1.90 [m]

weight cabin furbishing : 26.04 [kg]

weight cabin floor : 37.89 [kg]

bracing : 41.0 [kg]

fuselage covering ( 40.3 [m2] doped linen fabric) : 12.5 [kg]

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 675 [litre] main fuel tank empty : 54.0 [kg]

weight air conditioning : 12 [kg]

weight engine mounts & firewalls : 16 [kg]

total weight fuselage : 701 [kg](20.0 [%])

***************************************************************

weight plywood wing covering : 57 [kg]

total weight ribs (63 ribs) : 208 [kg]

load on front upper spar (clmax) per running metre : 988.3 [N]

load on rear upper spar (vmax) per running metre : 473.3 [N]

total weight 4 spars : 211 [kg]

weight wings : 476 [kg]

weight wing/square meter : 8.13 [kg]

cantilever wing without bracing cables

weight fin & rudder (4.3 [m2]) : 35.8 [kg]

weight stabilizer & elevator (6.6 [m2]): 54.0 [kg]

total weight wing surfaces & bracing : 566 [kg] (16.2 [%])

*******************************************************************

wheel pressure : 1750.0 [kg]

weight 2 wheels (1250 [mm] by 250 [mm]) : 92.4 [kg]

weight tailskid : 6.3 [kg]

weight undercarriage with axle 54.5 [kg]

total weight landing gear : 153.2 [kg] (4.4 [%]

*******************************************************************

********************************************************************

calculated empty weight : 1940 [kg](55.4 [%])

weight oil for 7.2 hours flying : 59.2 [kg]

calculated operational weight empty : 1999 [kg] (57.1 [%])

published operational weight empty : 1950 [kg] (55.7 [%])

***o***

weight crew : 162 [kg]

weight fuel for 2.0 hours flying : 154 [kg]

********************************************************************

operational weight empty: 2316 [kg](66.2 [%])

weight 8 passengers : 616 [kg]

weight luggage & freight : 184 [kg]

operational weight loaded: 3116 [kg](66.2 [%])

Overview of F.VIIa registrations (not all)

fuel reserve : 373.1 [kg] enough for 4.83 [hours] flying

possible additional useful load : 11 [kg]

operational weight fully loaded : 3500 [kg] with fuel tank filled for 100 [%]

published maximum take-off weight : 3500 [kg] (100.0 [%])

I||==|

calculation : * 4 * (engine power)

power loading (Take-off) : 10.67 [kg/kW]

power loading (operational without useful load) : 7.06 [kg/kW]

total power : 328.1 [kW] at 1700 [r.p.m]

calculation : *5* (loads)

manoeuvre load : 2.9 [g] at 1000 [m]

limit load : 3.0 [g] ultimate load : 4.5 [g] load factor : 1.6 [g]

design flight time : 4.21 [hours]

design cycles : 902 sorties, design hours : 3800 [hours]

operational wing loading : 388 [N/m^2]

wing stress (3 g) during operation : 143 [N/kg] at 3g emergency manoeuvre

calculation : *6* (angles of attack)

angle of attack zero lift : -1.24 ["]

max. angle of attack (stalling angle) : 12.89 ["]

angle of attack at max. speed : 1.61 ["]

calculation : *7* (lift & drag ratios

lift coefficient at angle of attack 0° :0.10 [ ]

lift coefficient at max. angle of attack : 1.14 [ ]

lift coefficient at max. speed : 0.23 [ ]

induced drag coefficient at max. speed : 0.0035 [ ]

drag coefficient at max. speed : 0.0411 [ ]

drag coefficient (zero lift) : 0.0376 [ ]

calculation : *8* (speeds

stalling speed at sea-level (OW loaded): 103 [km/u]

landing speed at sea-level: 121 [km/hr]

min. drag speed (max endurance) : 136 [km/hr] at 1450 [m](power :58 [%])

min. power speed (max range) : 136 [km/hr] at 1450 [m] (power:58 [%])

max. rate of climb speed : 114.8 [km/hr] at sea-level

cruising speed : 171 [km/hr] op 1450 [m] (power:81 [%])

design speed prop : 180 [km/hr]

maximum speed : 190 [km/hr] op 100 [m] (power:109 [%])

climbing speed at sea-level : 305 [m/min]

calculation : *9* (regarding various performances)

take-off speed : 125.3 [km/u]

emergency/TO power : 475 [hp] at 1870 [rpm]

static prop wash : 156 [km/u]

take-off distance at sea-level : 234 [m]

lift/drag ratio : 9.99 [ ]

climb to 1000m with max payload : 9.51 [min]

climb to 2000m with max payload : 26.29 [min]

climb to 3000m with max payload : 58.54 [min]

published ceiling (2900 [m]

practical ceiling (operational weight > 2316 kg) : 5713 [m]

practical ceiling fully loaded (mtow- 30 min.fuel > 3461 kg) : 3153 [m]

max. dive speed : 408.7 [km/hr] at 2153 [m] height

turning speed at CLmax : 128.0 [km/u] at 50 [m] height

turn radius at 50m: 64 [m]

time needed for 360* turn 11.2 [seconds] at 50m

load factor at max. angle turn 2.26 ["g"]

calculation *10* (action radius & endurance)

published range : 1029 [km] with 2 crew and 874.1 [kg] useful load and 88.1 [%] fuel

range : 1193 [km] with 2 crew and 800.0 [kg] useful load and 102.1 [%] fuel

range : 1423 [km] with 8.0 passengers with each 10 [kg] luggage and 121.9 [%] fuel

Available Seat Kilometers (ASK) : 11386 [paskm]

PH-ACT at Texel

max range theoretically with additional fuel tanks for total 1937.1 [litre] fuel : 3143.3 [km]

useful load with range 500km : 1194 [kg]

useful load with range 500km : 8 passengers

production (useful load): 204.18 [tonkm/hour]

production (passengers): 1368.00 [paskm/hour]

oil and fuel consumption per tonkm : 0.42 [kg]

oil and fuel consumption per paskm : 0.06 [kg]

fuel cost per paskm : 0.06 [eur]

writing off per paskm : 0.28 [eur]

insurance per paskm : 0.01 [eur]

crew cost per paskm : 0.11 [eur]

I=°°°°°/

maintenance cost per paskm : 0.31 [eur]

direct operating cost per paskm : 0.77 [eur]

F.VIIa c/n 5054 on it’s way to Schiphol airport, it is accompanied by the 2^nd Fokker F.27 prototype. Note the small balloon tyres fitted after WWII. This aircraft flew in Switzerland (CH-159, Balair,1928), in Denmark as OY-DED, DDL, 1930) and in Sweden (SE-ASE, Skane flyg, 1947) and was a gift to the Aviadome museum by Fokker and KLM in 1955. In 1985 it was restored and was on display in the Aviodome museum at Schiphol with registration H-NACT, now it can be seen in the Aviodrome museum in Lelystad with registration N-NADP.

Serious accidents :

*31 August 1927 F.VIIa G-EBTQ c/n 5023 “St. Raphael” piloted by Leslie Hamilton and Frederick F. Minchin , disappeared over the Atlantic Ocean on a flight from RAF Upavon, England to Ottowa, Canada. Passenger Princess Anne of Lowenstein-Wertheim-Freudenberg. All 3 on board died. For the first East to West crossing over the Atlantic ocean it had additional fuel tanks instored for total 4405 litre (3230 kg) enough for 40-42 hours flying (at ca. 157 km/hr cruise speed) It had a 450hp Bristol Jupiter engine. The runway was 2000m long.

Empty weight : 1950 kg + 2 crew 160 kg + 1 pax 70 kg + oil 350 kg + fuel 3230 kg = TOW 5760 kg calculated TO distance : 550m. Range with 4405 litre petrol would be around 6425 km. Flying distance Upavon – Ottowa = 5265 km. To cover this distance non-stop average headwind should not exceed 30 km/hr.

*F.VIIa NX703 “Old Glory” c/n 501 departed on 06 September 1927 from Old Orchard Beach for a non-stop flight to Rome (distance 6490 km). Crew Lloyd W. Bertaud and James DeWitt Hill . Philip A. Paine, New York daily Mirror editor flew as passenger. Ditched in Atlantic ocean, 350 mile east of Cape Race, Newfoundland. 12 September 1927 S.S.Kyle found the still floating wing, parts of the fuselage, fuel tanks, but no trace of the crew. The aircraft was owned by newspaper magnate William Randolph Hearst .

The fuselage and wing were built in the Netherlands, shipped to the U.S. and assembled in Hasbrouck Heights , Teterboro by the Atlantic Aircraft corp., a Fokker subsidiary, like most of the F.VIIa’s that flew in the U.S.

To fly non-stop 6490 km could be just possible with a little tailwind.

F.VIIa NX703 “Old Glory” on its take-off ramp with 450hp Bristol Jupiter engine. For the flight to Rome all-up weight was 12.700 pounds > 5760 kgs (normal MTOW was 3500 kg !)

With this weight the F.VIIa could only fly at max take-off power at ca.100m height ! No room for error. After about 1.5 hrs flying a more safe height of 250m could be reached when the aircraft was getting lighter by the burning of its fuel but still at max.power, if they throttle back a little flying height will have dropped again to ca. 100m

The F.VIIa also flew in the USA. NC7888 c/n 601, they were delivered by Atlantic Aircraft Corporation (fuselage and wing built in the Netherlands, assembled in Teterboro by Atlantic Aircraft corp.). NC7888 had a 525hp Pratt & Whitney Hornet engine and flew with Standard Airlines inc.

* 29 March 1929 F.VIIa NC7888 flew against a mountain in foggy conditions near Beaumont, California. Flight from Los Angeles to El Paso. All 4 on board died. Pilot : Delbert Everett

Literature :

Fokker verkeersvliegtuigen 1920-1940 page 22,23,24,25,26,27

Van Spin tot Fokker 100 page 19,22,60

Fokker – bouwer aan de wereldluchtvaart page 66,70

Word directory of airliner crashes page 14

Alles over de Fokker Friendship page 25 – 30, 114,115, 122(!)

Fokker verkeersvliegtuigen page 44 – 49, 56,57,58

Fokkers “Roaring Twenties” page 27

Praktisch handboek vliegtuigen deel 2 page 200

Vermist sinds 1927: de Fokker F.VIIa “St. Raphael” | It AvOliT (jmgrisnich.nl)

Fokker F.VIIa (fokker-history.com)

Old Glory's Final Ill-fated Flight: New York to Rome in 1927 (historynet.com)