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weight and performance calculations for the Thomas-Morse S-4C
Thomas-Morse S-4C
role : advanced trainer
importance : ***
first flight : operational : April 1918
country : United States of America
design : Benjamin Douglas Thomas
production : 597 aircraft, Ithaca, New York
general information :
Good flying qualities. B.D.Thomas had also designed the Curtiss JN-4 ‘Jenny’.
The S-4B with 100 hp Gnome engine was used by practically every pursuit flying
school in the U.S. during 1918. The Gnome engine was not reliable and was replaced by
the Le Rhone 9c rotary engine and this version was indicated as S4C
petrol tank capacity : 30 gallons = 113.5 litre (US gallon) endurance : 2.5 hrs
landing speed : 72 km/u. After WWI it continued to be flown for civil use.
users : USAF
crew : 1
armament : 1 synchronized 7.62 [mm] (0.300 in) Marlin M1917 machine-gun
engine : 1 Le Rhone 9c air-cooled 9 -cylinder two-valve rotary engine 90 [hp](66.2 KW)
dimensions :
wingspan : 8.08 [m], length : 6.05 [m], height : 2.47[m]
wing area : 21.74 [m^2]
weights :
max.take-off weight : 603 [kg]
empty weight operational : 0 [kg] bombload : 0 [kg]
performance :
maximum speed : 156 [km/hr] at sea-level
service ceiling : 4572 [m]
endurance : 3.9 [hours]
estimated action radius : 273 [km]
description :
1-bay biplane with fixed landing gear and tail strut
two spar upper and lower wing
engines, landing gear, fuel and bombs in or attached to the fuselage
airscrew :
fixed pitch 2 -bladed tractor airscrew with max. efficiency :0.64 [ ]
estimated diameter airscrew 2.43 [m]
angle of attack prop : 19.26 [ ]
reduction : 1.00 [ ]
airscrew revs : 1300 [r.p.m.]
pitch at Max speed 2.00 [m]
blade-tip speed at Vmax and max revs. : 171 [m/s]
calculation : *1* (dimensions)
mean wing chord : 1.35 [m]
calculated wing chord (rounded tips): 1.54 [m]
wing aspect ratio : 6.01 []
estimated gap : 1.24 [m]
gap/chord : 0.92 [ ]
seize (span*length*height) : 121 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 4.3 [kg/hr]
fuel consumption(cruise speed) : 18.8 [kg/hr] (25.6 [litre/hr]) at 66 [%] power
distance flown for 1 kg fuel : 7.49 [km/kg]
estimated total fuel capacity : 113 [litre] (83 [kg])
calculation : *3* (weight)
weight engine(s) dry : 122.0 [kg] = 1.84 [kg/KW]
weight 24 litre oil tank : 3.0 [kg]
oil tank filled with 0.5 litre oil : 0.4 [kg]
oil in engine 0 litre oil : 0.3 [kg]
fuel in engine 0 litre fuel : 0.3 [kg]
weight 11 litre gravity patrol tank(s) : 1.1 [kg]
weight cowling 2.6 [kg]
weight airscrew(s) (wood) incl. boss & bolts : 15.2 [kg]
total weight propulsion system : 142 [kg](23.6 [%])
***************************************************************
fuselage skeleton (wood gauge : 5.10 [cm]): 40 [kg]
bracing : 1.7 [kg]
fuselage covering ( 6.9 [m2] doped linen fabric) : 2.2 [kg]
weight controls + indicators: 5.2 [kg]
weight seats : 3.0 [kg]
weight other details, lighting set, etc. : 5.1 [kg]
weight 102 [litre] main fuel tank empty : 9.8 [kg]
weight oxygen/compressed air flasks for high altitude : 4.2 [kg]
weight engine mounts & firewalls : 3 [kg]
total weight fuselage : 75 [kg](12.4 [%])
***************************************************************
weight wing covering (doped linen fabric) : 14 [kg]
total weight ribs (37 ribs) : 36 [kg]
load on front upper spar (clmax) per running metre : 622.2 [N]
load on rear upper spar (vmax) per running metre : 210.2 [N]
total weight 8 spars : 23 [kg]
weight wings : 73 [kg]
weight wing/square meter : 3.36 [kg]
weight 4 interplane struts & cabane : 5.3 [kg]
weight cables (40 [m]) : 1.5 [kg] (= 37 [gram] per metre)
diameter cable : 2.4 [mm]
weight fin & rudder (0.8 [m2]) : 2.7 [kg]
weight stabilizer & elevator (2.4 [m2]): 8.4 [kg]
total weight wing surfaces & bracing : 91 [kg] (15.1 [%])
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weight machine-gun(s) : 11.3 [kg]
weight ammunition magazine(s) :2.2 [kg]
weight mechanical synchronization gear : 1.0 [kg]
weight armament : 14 [kg]
********************************************************************
wheel pressure : 301.5 [kg]
weight 2 wheels (620 [mm] by 73 [mm]) : 11.5 [kg]
weight tailskid : 1.5 [kg]
weight undercarriage with axle 16.1 [kg]
total weight landing gear : 29.2 [kg] (4.8 [%]
*******************************************************************
********************************************************************
calculated empty weight : 351 [kg](58.3 [%])
weight oil for 4.7 hours flying : 20.1 [kg]
weight ammunition (500 rounds) : 13.6 [kg]
weight signal pistol with cartridges : 3.6 [kg]
*******************************************************************
calculated operational weight empty : 389 [kg] (64.5 [%])
estimated operational weight empty : 357 [kg] (59.2 [%])
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weight crew : 81 [kg]
weight (electrical heated) clothing for high altitude : 6.0 [kg]
weight fuel for 2.0 hours flying : 38 [kg]
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operational weight : 513 [kg](85.1 [%])
estimated bomb load : 50 [kg]
operational weight bombing mission : 563 [kg]
fuel reserve : 40 [kg] enough for 2.12 [hours] flying
operational weight fully loaded : 603 [kg] with fuel tank filled for 93 [%]
published maximum take-off weight : 603 [kg] (100.0 [%])
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calculation : * 4 * (engine power)
power loading (operational without bombload) : 7.75 [kg/kW]
total power : 66.2 [kW] at 1300 [r.p.m]
calculation : *5* (loads)
manoeuvre load : 3.2 [g] at 1000 [m]
limit load : 3.75 [g] ultimate load : 5.6 [g] load factor : 2.2 [g]
design flight time : 3.11 [hours]
design cycles : 337 sorties, design hours : 1050 [hours]
operational wing loading : 232 [N/m^2]
wing stress (3 g) during operation : 207 [N/kg] at 3g emergency manoeuvre
calculation : *6* (angles of attack)
angle of attack zero lift : -1.26 ["]
max. angle of attack (stalling angle) : 13.03 ["]
angle of attack at max. speed : 1.31 ["]
calculation : *7* (lift & drag ratios
lift coefficient at angle of attack 0° :0.10 [ ]
lift coefficient at max. angle of attack : 1.13 [ ]
lift coefficient at max. speed : 0.20 [ ]
induced drag coefficient at max. speed : 0.0039 [ ]
drag coefficient at max. speed : 0.0388 [ ]
drag coefficient (zero lift) : 0.0349 [ ]
calculation : *8* (speeds
stalling speed at sea-level (OW): 66 [km/u]
landing speed at sea-level (OW without bombload): 79 [km/hr]
min. drag speed (max endurance) : 100 [km/hr] at 2286 [m](power :42 [%])
min. power speed (max range) : 107 [km/hr] at 2286 [m] (power:44 [%])
max. rate of climb speed : 95.6 [km/hr] at sea-level
cruising speed : 140 [km/hr] op 2286 [m] (power:66 [%])
design speed prop : 148 [km/hr]
maximum speed : 156 [km/hr] op 100 [m] (power:99 [%])
climbing speed at sea-level (without bombload) : 257 [m/min]
calculation : *9* (regarding various performances)
take-off distance at sea-level : 156 [m]
lift/drag ratio : 8.71 [ ]
max. practical ceiling : 5200 [m] with flying weight :462 [kg]
practical ceiling (operational weight) : 4575 [m] with flying weight :513 [kg] line 3385
practical ceiling fully loaded (mtow- 1 hour fuel) : 3775 [m] with flying weight :584 [kg]
published ceiling (4572 [m]
climb to 1500m (without bombload) : 6.58 [min]
climb to 3000m (without bombload) : 16.58 [min]
max. dive speed : 339.1 [km/hr] at 2775 [m] height
load factor at max. angle turn 1.92 ["g"]
turn radius at 500m: 42 [m]
time needed for 360* turn 10.2 [seconds] at 500m
calculation *10* (action radius & endurance)
operational endurance : 4.42 [hours] with 1 crew and 50 [kg] useful (bomb)load and 100.0 [%] fuel
published endurance : 3.89 [hours] with 1 crew and possible useful (bomb) load : 60 [kg] and 88.1 [%] fuel
action radius : 424 [km] with 1 crew and 20[kg] photo camera or bombload
max range theoretically with additional fuel tanks for total 205 [litre] fuel : 1126 [km]
useful load with action-radius 250km : 84 [kg]
production : 11.75 [tonkm/hour]
oil and fuel consumption per tonkm : 1.96 [kg]
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Literature :
fighters 1914-19 page 70
Praktisch handboek vliegtuigen deel 1 page 239
Jane’s fighting aircraft WWI page 250
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 12 April 2020 contact : info.aircraftinvestigation@gmail.com python 3.7.4