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weight and performance calculations for the Boeing 247
At first the 247 had a forward angled windscreen to prevent the reflecting of the lighted instruments in the night on the screen. But this resulted in ground lights to reflect on the screen, especially during landing. In the 247D the screen was sloped aft, in the usual way and a glarescreen over the instruments prevented the reflection on the windscreen
Boeing 247
role : multi-engined passenger aircraft
importance : ****
first flight : 08 February 1933 operational : 22 May 1933
country : United States of America
design :
production : 75 aircraft
general information :
Advanced design, all metal semimonocoque construction with retractable landing gear, auto-pilot and de-icing boots. First 2-engined passenger aircraft what could stay in the air with one engine out. It was fast and safe. The low landing speed of 100 km/hr precluded the need of flaps. Set the standard for the next airliners, like the Douglas DC.1 and Lockheed Electra series. At first the 247 had only ground adjustable airscrews. At high speed pitch the take-off performance was not so good, this was later cured in the 247D variant with variable pitch propellors, coming into service in October 1934. The variable pitch propellors were retrofitted to the 247’s already built.
For passenger comfort it had a thermostatically-controlled, air conditioned and soundproof cabin.
Crew consisted of a pilot, co-pilot and a stewardess, who could tend the passengers needs.
The Boeing 247 had speed-ring engine cowlings (Townend ring), the later 247D had NACA Cowlings.
In May 1933 a 247 set a USA cross country record by flying in 19.5 hrs from San Francisco to New York. The 247 was sold for the price of 65.000 usd in 1933.
users : United Air Lines(10), Boeing Air Transport (60), Lufthansa(2), Western Air
Express(2 nd hand)
crew : 3 passengers : 10
engine : 2 Pratt & Whitney R-1340 Wasp air-cooled 9 -cylinder radial engine 525 [hp]
(391.5 KW) supercharged engine, constant power to height : 2250 [m]
dimensions :
wingspan : 22.58 [m], length : 15.72 [m], height : 3.7 [m]
wing area : 77.68 [m^2]
weights :
max.take-off weight : 6192 [kg]
empty weight operational : 4046 [kg] useful load : 1180 [kg]
performance :
maximum speed :305 [km/u] op 2000 [m]
cruise speed :290 [km/u] op 2000 [m]
service ceiling : 7700 [m]
range : 1114 [km]
description :
low-winged monoplane with retractable landing gear with tail wheel
tapered wing with no flaps airfoil : Boeing 106B
engines and landing gear attached to the wings, fuel tanks in the wings
construction : all-metal stressed-skin (duraluminium) airplane
airscrew :
ground adjustable 3 -bladed metal Hamilton Standard tractor propeller with max.
efficiency :0.73 [ ]
estimated diameter airscrew 3.14 [m]
power loading prop : 83.12 [KW/m]
angle of attack prop : 24.75 [ ]
reduction : 0.67 [ ]
airscrew revs : 1491 [r.p.m.]
pitch at Max speed 3.41 [m]
blade-tip speed at Vmax and max revs. : 259 [m/s]
calculation : *1* (dimensions)
measured wing chord : 3.53 [m] at 50% wingspan
mean wing chord : 3.44 [m]
calculated average wing chord tapered wing with rounded tips: 3.38 [m]
The 247 prototype in mid air
wing aspect ratio : 6.56 []
seize (span*length*height) : 1313 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 11.0 [kg/hr]
fuel consumption(cruise speed) : 172.6 [kg/hr] (235.5 [litre/hr]) at 72 [%] power
distance flown for 1 kg fuel : 1.68 [km/kg] at 3850 [m] height, sfc : 308.2 [kg/kwh]
estimated total fuel capacity : 1027 [litre] (753 [kg])
calculation : *3* (weight)
weight engine(s) dry : 800.0 [kg] = 1.02 [kg/KW]
weight reduction gear : 33.7 [kg]
weight 75.9 litre oil tank : 6.45 [kg]
oil tank filled with 5.9 litre oil : 5.3 [kg]
oil in engine 4.4 litre oil : 3.9 [kg]
fuel in engine 5.3 litre fuel : 3.91 [kg]
weight 100.1 litre gravity patrol tank(s) : 15.0 [kg]
weight starter (E.H.I. - Electric Hand Inertia): 9.6 [kg]
weight cowling (Townend ring) 15.7 [kg]
weight airscrew(s) incl. boss & bolts : 119.7 [kg]
total weight propulsion system : 1040 [kg](16.8 [%])
***************************************************************
fuselage aluminium frame : 673 [kg]
cabin layout : pitch : 87 [cm] (1+1) seating in 5.0 rows
weight toilet : 8 [kg]
weight 2 fire extinguisher : 6 [kg]
weight 10 windows : 9.0 [kg]
passenger cabin width : 1.68 [m] cabin length : 4.95 [m] cabin height : 1.90 [m]
weight cabin furbishing : 36.5 [kg]
weight cabin floor : 53.2 [kg]
fuselage covering ( 68.3 [m2] duraluminium 1.94 [mm]) : 349.9 [kg]
fuselage (sound proof) isolation : 20.0 [kg]
weight radio transceiver equipment : 7.0 [kg]
weight Sperry gyro auto-pilot - course control equipment : 1.5 [kg]
weight instruments. : 6.0 [kg]
weight lighting : 2.5 [kg]
weight electricity generator : 5.6 [kg]
The stewardess was introduced in the 1930’s
weight controls : 8.1 [kg]
weight seats : 65.0 [kg]
weight air conditioning : 15 [kg]
total weight fuselage : 1240 [kg](20.0 [%])
***************************************************************
total weight aluminium ribs (92 ribs) : 221 [kg]
weight engine mounts : 39 [kg]
weight two 464 [litre] main fuel tanks empty : 74.2 [kg]
weight wing covering (painted aluminium 1.03 [mm]) : 434 [kg]
total weight 4 aluminium spars : 347 [kg]
weight wings : 1002 [kg]
weight wing/square meter : 12.90 [kg]
cantilever wing without bracing cables
weight fin & rudder (5.9 [m2]) : 77.2 [kg]
weight stabilizer & elevator (8.7 [m2]): 113.3 [kg]
total weight wing surfaces & bracing : 1330 [kg] (21.5 [%])
*******************************************************************
wheel pressure : 3096.0 [kg]
weight 2 wheels (1180 [mm] by 236 [mm]) : 149.5 [kg]
weight tailwheel(s) : 5.9 [kg]
weight wheel hydraulic operated retraction system : 27.2 [kg]
weight undercarriage with axle 226.0 [kg]
total weight landing gear : 408.6 [kg] (6.6 [%]
*******************************************************************
********************************************************************
calculated empty weight : 4019 [kg](64.9 [%])
weight oil for 4.6 hours flying : 50.6 [kg]
calculated operational weight empty : 4070 [kg] (65.7 [%])
published operational weight empty : 4046 [kg] (65.3 [%])
weight crew : 243 [kg]
weight fuel for 2.0 hours flying : 345 [kg]
weight catering : 15.4 [kg]
weight water : 6.2 [kg]
********************************************************************
operational weight empty: 4679 [kg](75.6 [%])
weight 10 passengers : 770 [kg]
weight luggage & freight : 410 [kg]
operational weight loaded: 5859 [kg](94.6 [%])
fuel reserve : 332.7 [kg] enough for 1.93 [hours] flying
operational weight fully loaded : 6192 [kg] with fuel tank filled for 90 [%]
published maximum take-off weight : 6192 [kg] (100.0 [%])
calculation : * 4 * (engine power)
power loading (Take-off) : 7.91 [kg/kW]
power loading (operational without useful load) : 5.98 [kg/kW]
power loading (Take-off) 1 PUF: 15.82 [kg/kW]
total power : 783.0 [kW] at 2235 [r.p.m]
calculation : *5* (loads)
manoeuvre load : 6.4 [g] at 1000 [m]
limit load : 3.0 [g] ultimate load : 4.5 [g] load factor : 2.5 [g]
design flight time : 3.08 [hours]
design cycles : 8537 sorties, design hours : 26258 [hours]
operational wing loading : 591 [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 : -1.97 ["]
max. angle of attack (stalling angle) : 14.08 ["]
angle of attack at max. speed : 0.04 ["]
calculation : *7* (lift & drag ratios
lift coefficient at angle of attack 0° : 0.16 [ ]
lift coefficient at max. angle of attack : 1.30 [ ]
lift coefficient at max. speed : 0.16 [ ]
induced drag coefficient at max. speed : 0.0017 [ ]
drag coefficient at max. speed : 0.0239 [ ]
drag coefficient (zero lift) : 0.0221 [ ]
calculation : *8* (speeds
stalling speed at sea-level (OW loaded : 6019 [kg]): 111 [km/u]
landing speed at sea-level (normal landing weight : 4984 [kg]): 116 [km/hr]
max. endurance speed : 152 [km/u] min. brpu : 106 [kg/hr] at cruise height : 100 [m]
max. rate of climb speed : 175.6 [km/hr] at sea-level
max. range speed : 229 [km/u] min.fuel cons.: 0.562 [kg/km] at cruise height : 4425 [m]
Lufthansa flew with two 247’s, this is D-AGAR in front of a KLM hangar at Schiphol airport. Note the 2 bladed propellor
cruising speed : 290 [km/hr] at 3850 [m] (power:53 [%])
maximum speed : 305 [km/hr] at 2000 [m] (power:68 [%])
climbing speed at sea-level (loaded) : 270 [m/min]
climbing speed at 1000 [m] with 1 engine out (PUF / MTOW) : 34 [m/min]
calculation : *9* (regarding various performances)
take-off speed : 135.2 [km/u]
emergency/TO power : 570 [hp] at 2329 [rpm]
static prop wash : 95 [km/u]
take-off distance at sea-level : 554 [m]
lift/drag ratio : 13.21 [ ]
climb to 1000m with max payload : 1.96 [min]
climb to 2000m with max payload : 3.89 [min]
climb to 3000m with max payload : 5.91 [min]
practical ceiling (operational weight 4679 [kg] ) : 9323 [m]
practical ceiling fully loaded (mtow- 30 min.fuel:6106 [kg] ) : 8143 [m]
calculation *10* (action radius & endurance)
published range : 1114 [km] with 3 crew and 1215.9 [kg] useful load and 88.1 [%] fuel
range : 1174 [km] with 3 crew and 1180.0 [kg] useful load and 92.9 [%] fuel
range : 1695 [km] with 10.0 passengers with each 10 [kg] luggage and 134.0 [%] fuel
Available Seat Kilometres (ASK) : 16946 [paskm]
max range theoretically with additional fuel tanks total 2785.0 [litre] fuel : 3633 [km]
useful load with range 500km : 1744 [kg]
useful load with range 500km : 10 passengers
production (useful load): 505 [tonkm/hour]
production (passengers): 2898 [paskm/hour]
combi aircraft mail/freight/passengers
oil and fuel consumption per tonkm : 0.36 [kg]
fuel cost per paskm : 0.036 [eur]
crew cost per paskm : 0.059 [eur]
economic hours : 12775 [hours] is less then design hours
time between engine failure : 98 [hr]
can continue fly on 1 engine, low risk for emergency landing for PUF
writing off per paskm : 0.052 [eur]
insurance per paskm : 0.023 [eur]
maintenance cost per paskm : 0.164 [eur]
direct operating cost per paskm : 0.334 [eur]
direct operating cost per tonkm : 3.342 [eur]
Literature :
Piston-engined airliners page
Praktisch handboek vliegtuigen deel 2 page
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 22 October 2021 contact : info.aircraftinvestigation@gmail.com python 3.7.4