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weight and performance calculations for the Northrop Delta
Northrop Delta
role : medium weight passenger aircraft
importance : ****
first flight : May 1933 operational : September 1933
country : United States of America
design : Jack Northrop
production : 32 aircraft (including 19 license built by Canadian Vickers)
general information :
low operating cost. Low drag co-efficient > nicely streamlined. New FAA regulations for single engine / single pilot passenger aircraft operating in the night or over rough terrain in October 1934 limited its use as passenger aircraft in the US.
Engines installed were the P&W Hornet or Wright Cyclone in different versions.
19 Delta’s were built by Canadian Vickers for the RCAF
users : TWA, A.B. Aerotransport
crew : 1 passengers : 8
engine : 1 Wright SR-1820-F2 Cyclone air-cooled 9 -cylinder radial engine 660 [hp](492.2 KW)
without supercharger
dimensions :
wingspan : 14.55 [m], length : 10.08 [m], height : 3.07[m]
wing area : 33.7 [m^2]
weights :
max.take-off weight : 3334 [kg]
empty weight operational : 2059 [kg] useful load : 800 [kg]
performance :
maximum speed :297 [km/u] op 1920 [m]
cruise speed :282 [km/u] op 1920 [m]
service ceiling : 6095 [m]
range : 1250 [km]
description :
low-winged monoplane with fixed landing gear with tail wheel
tapered wing with split flap
engine in the nose, fuel tanks in the wing, landing gear attached to the wing
construction : all-metal stressed-skin (duraluminium) airplane
airscrew :
ground adjustable 2 -bladed metal Hamilton Standard tractor propeller with max.
efficiency :0.73 [ ]
estimated diameter airscrew 3.09 [m]
Chord at root (measured) : 2.89 [m]
power loading prop : 159.28 [KW/m]
prop efficiency ratio: 9.73 [1/s]
angle of attack prop : 19.21 [ ]
reduction : 1.00 [ ]
airscrew revs : 1950 [r.p.m.]
pitch at Max speed 2.54 [m]
blade-tip speed at Vmax and max revs. : 326 [m/s]
calculation : *1* (dimensions)
measured wing chord : 2.35 [m] at 50% wingspan
mean wing chord : 2.32 [m]
wing aspect ratio : 6.28 []
seize (span*length*height) : 450 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 6.9 [kg/hr]
fuel consumption(cruise speed) : 105.5 [kg/hr] (143.9 [litre/hr]) at 58 [%] power
distance flown for 1 kg fuel : 2.67 [km/kg] at 3048 [m] height, sfc : 368.1 [kg/kwh]
estimated total fuel capacity : 724 [litre] (531 [kg])
calculation : *3* (weight)
weight engine(s) dry : 406.0 [kg] = 0.82 [kg/KW]
weight 53.1 litre oil tank : 4.52 [kg]
oil tank filled with 3.7 litre oil : 3.3 [kg]
The Delta used split flaps for better landing performance
oil in engine 2.7 litre oil : 2.5 [kg]
fuel in engine 3.4 litre fuel : 2.46 [kg]
weight 61.2 litre gravity patrol tank(s) : 9.2 [kg]
weight gas starter : 12.1 [kg]
weight NACA cowling 22.0 [kg]
weight airscrew(s) (wood) incl. boss & bolts : 48.7 [kg]
total weight propulsion system : 506 [kg](15.2 [%])
***************************************************************
fuselage aluminium frame : 271 [kg]
cabin layout : pitch : 87 [cm] (1+1) seating in 4.0 rows
weight toilet : 8 [kg]
weight 2 fire extinguisher : 6 [kg]
weight 8.0 windows : 7.20 [kg]
passenger cabin width : 1.40 [m] cabin length : 4.08 [m] cabin height : 1.80 [m]
cabin length / length : 40.5 [%]
weight cabin furbishing : 21.74 [kg]
weight cabin floor : 36.49 [kg]
fuselage covering ( 19.2 [m2] duraluminium 1.47 [mm]) : 71.1 [kg]
weight radio navigation equipment : 7.0 [kg]
weight instruments. : 5.0 [kg]
weight lighting : 2.0 [kg]
weight electricity generator : 2.0 [kg]
weight controls : 5.6 [kg]
weight seats : 45.0 [kg]
weight air conditioning : 12 [kg]
weight engine mounts & firewalls : 25 [kg]
total weight fuselage : 522 [kg](15.7 [%])
***************************************************************
total weight aluminium ribs (74 ribs) : 119 [kg]
weight fuel tanks empty for total 663 [litre] fuel : 53 [kg]
weight wing covering (painted aluminium 1.54 [mm]) : 281 [kg]
load on front upper spar (clmax) per running metre : 2705.4 [N]
load on rear upper spar (vmax) per running metre : 698.4 [N]
total weight 4 aluminium spars : 200 [kg]
weight wings : 600 [kg]
weight wing/square meter : 17.82 [kg]
cantilever wing without bracing cables
weight rubber de-icing boots : 16.0 [kg]
weight fin & rudder (2.5 [m2]) : 44.1 [kg]
weight stabilizer & elevator (3.8 [m2]): 67.8 [kg]
weight split flap(1.7 [m2]) : 18.0 [kg]
total weight wing surfaces & bracing : 799 [kg] (24.0 [%])
*******************************************************************
wheel pressure : 1667.0 [kg]
weight 2 wheels (920 [mm] by 142 [mm]) : 81.0 [kg]
weight tailwheel(s) : 5.9 [kg]
weight undercarriage with axle 116.2 [kg]
total weight landing gear : 203.1 [kg] (6.1 [%]
*******************************************************************
********************************************************************
calculated empty weight : 2031 [kg](60.9 [%])
weight oil for 5.3 hours flying : 36.7 [kg]
calculated operational weight empty : 2068 [kg] (62.0 [%])
published operational weight empty : 2059 [kg] (61.8 [%])
___o___
‘ ‘
weight crew : 81 [kg]
weight fuel for 2.0 hours flying : 211 [kg]
********************************************************************
operational weight empty: 2360 [kg](70.8 [%])
weight 8 passengers : 616 [kg]
weight luggage & freight : 184 [kg]
operational weight loaded: 3160 [kg](94.8 [%])
fuel reserve : 174.5 [kg] enough for 1.65 [hours] flying
operational weight fully loaded : 3334 [kg] with fuel tank filled for 73 [%]
published maximum take-off weight : 3334 [kg] (100.0 [%])
calculation : * 4 * (engine power)
power loading (Take-off) : 6.77 [kg/kW]
power loading (operational without useful load) : 4.79 [kg/kW]
total power : 492.2 [kW] at 1950 [r.p.m]
calculation : *5* (loads)
manoeuvre load : 5.1 [g] at 1000 [m]
limit load : 3.0 [g] ultimate load : 4.5 [g] load factor : 2.9 [g]
design flight time : 3.55 [hours]
design cycles : 10858 sorties, design hours : 38502 [hours]
operational wing loading : 687 [N/m^2]
wing stress (3 g) during operation : 116 [N/kg] at 3g emergency manoeuvre
calculation : *6* (angles of attack)
angle of attack zero lift : -1.87 ["]
max. angle of attack (stalling angle) : 14.30 ["]
angle of attack at max. speed : 0.61 ["]
calculation : *7* (lift & drag ratios
lift coefficient at angle of attack 0° : 0.15 [ ]
lift coefficient at max. angle of attack : 1.30 [ ]
max.lift coefficient full flaps : 1.37 [ ]
lift coefficient at max. speed : 0.20 [ ]
induced drag coefficient at max. speed : 0.0027 [ ]
drag coefficient at max. speed : 0.0286 [ ]
drag coefficient (zero lift) : 0.0259 [ ]
calculation : *8* (speeds
stalling speed at sea-level (OW loaded : 3229 [kg]): 124 [km/u]
stalling speed at sea-level with full flaps : 121 [km/u]
landing speed at sea-level : 142 [km/hr]
min. drag speed (max endurance) : 208 [km/hr] at 3048 [m](power :43 [%])
min. power speed (max range) : 208 [km/hr] at 3048 [m] (power:43 [%])
max. rate of climb speed : 186.7 [km/hr] at sea-level
cruising speed : 282 [km/hr] at 3048 [m] (power:69 [%])
design speed prop : 289 [km/hr]
maximum speed : 297 [km/hr] at 1920 [m] (power:83 [%])
climbing speed at sea-level (loaded) : 342 [m/min]
calculation : *9* (regarding various performances)
take-off speed : 151.0 [km/u]
emergency/TO power : 735 [hp] at 2122 [rpm]
static prop wash : 177 [km/u]
take-off distance at sea-level : 265 [m]
lift/drag ratio : 11.95 [ ]
climb to 1000m with max payload : 3.81 [min]
climb to 2000m with max payload : 9.10 [min]
climb to 3000m with max payload : 16.20 [min]
practical ceiling (operational weight 2360 [kg] ) : 6478 [m]
practical ceiling fully loaded (mtow- 30 min.fuel:3281 [kg] ) : 4703 [m]
calculation *10* (action radius & endurance)
published range : 1250 [km] with 1 crew and 717.8 [kg] useful load and 88.1 [%] fuel
range : 1030 [km] with 1 crew and 800.0 [kg] useful load and 72.6 [%] fuel
range : 1308 [km] with 8.0 passengers with each 10 [kg] luggage and 92.2 [%] fuel
Available Seat Kilometres (ASK) : 10467 [paskm]
max range theoretically with additional fuel tanks total 1617.3 [litre] fuel : 3169 [km]
useful load with range 500km : 998 [kg]
useful load with range 500km : 8 passengers
production (useful load): 281.55 [tonkm/hour]
production (passengers): 2256.00 [paskm/hour]
oil and fuel consumption per tonkm : 0.40 [kg]
oil and fuel consumption per paskm : 0.04 [kg]
fuel cost per paskm : 0.04 [eur]
crew cost per paskm : 0.05 [eur]
economic hours : 12775 [hours] is less then design hours
time between engine failure : 135 [hr]
in case of engine failure only option is emergency landing
writing off per paskm : 0.05 [eur]
insurance per paskm : 0.05 [eur]
maintenance cost per paskm : 0.13 [eur]
direct operating cost per paskm : 0.33 [eur]
direct operating cost per tonkm : 3.27 [eur]
Literature :
Piston-engined airliners page 29
Praktisch handboek vliegtuigen deel 2 page 255
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
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(c) B van der Zalm 18 September 2021 contact : info.aircraftinvestigation@gmail.com python 3.7.4