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Sopwith type 9400 1½-Strutter
role : multi role combat aircraft
first flight : end 1915 operational : April 1916
country : United-Kingdom
design :
production : 5939 aircraft (4500 license built in France !)
general information :
When introduced the 1½-Strutter featured some innovations. It posessed air-brakes for short landings, a patented variable-incidence tailplane, the first British aircraft with a reliable synchronized machien gun and the movable Lewis-machine gun for the observer was placed on a new, by F.W.Scarff developped, Scarff-ring.
April 1916 it entered service with RNAS no.5 Wing first used as bomber escort but later the same year as bomber. For this purpose it was converted to a single-seater, indicated as Type 9700. The place of the observer was replaced with a rack that could hold four 29.5 kg bombs. As bomber it had a good range and the Type 9700 could be used as the first strategic bomber.
The 1½-Strutters entered service with the RFC summer 1916 during the Somme battle.
Juli 1916 it was the only operational British aircraft that had a synchronized machine gun a year after the introduction of the German Fokker E.I with synchronized Spandau machine gun !
The 1½-Strutter was also used on the first British aircraft carrier ships (HMS Argus, Furious and Vindex) and named Ship Strutters.
The France had also received some 1½-Strutters spring 1916 and they began to built the aircraft under license on a large scale. The French produced around 4500 1½-Strutters !
The 2-seat Reconnaisance version was indicated by the French as 1A2, 2-seat bomber as 1B2 and the 1-seat bomber as 1B1.
During bloody April the Strutters counted many losses. The single seat-bomber version was vulnerable for attacks from behind without the observer defending the tail. Mid 1917 the British started to withdraw the Strutters from the France front and relocated to the UK for home-defense night-fighter duties. The last Strutters were withdrawn October 1917.
The Belgian air force used the 1½-Strutters till 1920 !
The 1½-Strutters had a good performance and was easy to fly, but it was difficult for maintenance and also it was built lightly and fort hat could not take much battle damage. The Clerget engine was unreliable and not powerfull enough in the end to give sufficient performance to a armed two-seater.
RAF museum Londen
crew : 2
users : RNAS,RFC, France(4500), Belgium(70), Russia, USA(AEF,training), The Netherlands (5 aircraft interned)
armament : 1 synchronized 7.70 [mm] (0.303 in) Vickers machine-gun
and 1 movable 7.70 [mm] (0.303 in) Lewis machine-gun for the observer
engine : 1 Clerget 9B air-cooled 9 -cylinder two-valve rotary engine 130 [hp](95.6 KW)
dimensions :
wingspan : 10.21 [m], length : 7.7 [m], height : 3.12[m]
wing area : 32.14 [m^2]
weights :
max.take-off weight : 998 [kg]
empty weight operational : 593 [kg] bombload : 60 [kg]
performance :
maximum speed : 160 [km/u] op 1981 [m]
service ceiling : 3962 [m]
endurance : 4.0 [hours]
estimated action radius : 288 [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 :0.66 [ ]
estimated diameter airscrew 2.82 [m]
angle of attack prop : 17.80 [ ]
reduction : 1.00 [ ]
airscrew revs : 1250 [r.p.m.]
pitch at Max speed 2.13 [m]
blade-tip speed at Vmax and max revs. : 190 [m/s]
calculation : *1* (dimensions)
mean wing chord : 1.57 [m]
calculated wing chord (rounded tips): 1.77 [m]
wing aspect ratio : 6.49 []
estimated gap : 1.50 [m]
gap/chord : 0.95 [ ]
seize (span*length*height) : 245 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 6.0 [kg/hr]
fuel consumption(cruise speed) : 30.3 [kg/hr] (41.3 [litre/hr]) at 69 [%] power
distance flown for 1 kg fuel : 4.76 [km/kg]
estimated total fuel capacity : 187 [litre] (137 [kg])
calculation : *3* (weight)
weight engine(s) dry : 173.0 [kg] = 1.81 [kg/KW]
weight 35 litre oil tank : 2.9 [kg]
oil tank filled with 0.7 litre oil : 0.6 [kg]
oil in engine 1 litre oil : 0.5 [kg]
fuel in engine 1 litre fuel : 0.5 [kg]
weight 18 litre gravity patrol tank(s) : 2.6 [kg]
weight cowling 3.8 [kg]
weight airscrew(s) (wood) incl. boss & bolts : 19.0 [kg]
total weight propulsion system : 200 [kg](20.0 [%])
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Adj "Gusto" de Mevius and Capt Roger d'Hendecourt of n° 4 Squadron in their Sopwith 1 1/2 Strutter in 1917.
fuselage skeleton (wood gauge : 6.29 [cm]): 78 [kg]
bracing : 4.2 [kg]
fuselage covering ( 11.2 [m2] doped linen fabric) : 3.6 [kg]
weight controls + indicators: 5.9 [kg]
weight seats : 6.0 [kg]
weight other details, lighting set, etc. : 5.1 [kg]
weight bomb storage : 4.2 [kg]
weight 170 [litre] main fuel tank empty : 13.6 [kg]
weight engine mounts & firewalls : 5 [kg]
total weight fuselage : 126 [kg](12.6 [%])
***************************************************************
weight wing covering (doped linen fabric) : 21 [kg]
total weight ribs (52 ribs) : 59 [kg]
load on front upper spar (clmax) per running metre : 736.9 [N]
load on rear upper spar (vmax) per running metre : 270.8 [N]
total weight 8 spars : 44 [kg]
weight wings : 124 [kg]
weight wing/square meter : 3.86 [kg]
weight 4 interplane struts & cabane : 11.4 [kg]
weight cables (50 [m]) : 3.5 [kg] (= 69 [gram] per metre)
diameter cable : 3.4 [mm]
weight fin & rudder (1.2 [m2]) : 4.8 [kg]
weight stabilizer & elevator (3.6 [m2]): 14.2 [kg]
total weight wing surfaces & bracing : 158 [kg] (15.8 [%])
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The French were impressed by the Strutter and started license production. October 1916 15 Strutters were in service with the French.
weight machine-gun(s) : 28.6 [kg]
weight Scarff ring mounting mg :5.0 [kg]
weight ammunition magazine(s) :1.8 [kg]
weight synchronizing system : 1.0 [kg]
weight armament : 36 [kg]
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wheel pressure : 499.0 [kg]
weight 2 wheels (750 [mm] by 94 [mm]) : 21.6 [kg]
weight tailskid : 2.3 [kg]
weight undercarriage with axle 26.8 [kg]
total weight landing gear : 50.8 [kg] (5.1 [%]
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calculated empty weight : 571 [kg](57.2 [%])
weight oil for 4.8 hours flying : 28.9 [kg]
weight 5 drums empty : 1.0 [kg]
weight ammunition (635 rounds) : 22.6 [kg]
*******************************************************************
calculated operational weight empty : 622 [kg] (62.3 [%])
published operational weight empty : 593 [kg] (59.4 [%])
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weight crew : 162 [kg]
weight fuel for 2.0 hours flying : 61 [kg]
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operational weight : 845 [kg](84.6 [%])
bomb load : 60 [kg]
operational weight bombing mission : 905 [kg]
fuel reserve : 77 [kg] enough for 2.54 [hours] flying
possible additional useful load : 17 [kg]
operational weight fully loaded : 998 [kg] with fuel tank filled for 100 [%]
published maximum take-off weight : 998 [kg] (100.0 [%])
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calculation : * 4 * (engine power)
power loading (operational without bombload) : 8.83 [kg/kW]
total power : 95.6 [kW] at 1250 [r.p.m]
calculation : *5* (loads)
manoeuvre load : 3.1 [g] at 1000 [m]
limit load : 3.75 [g] ultimate load : 5.6 [g] load factor : 2.0 [g]
design flight time : 3.20 [hours]
design cycles : 281 sorties, design hours : 900 [hours]
operational wing loading : 258 [N/m^2]
wing stress (3 g) during operation : 201 [N/kg] at 3g emergency manoeuvre
calculation : *6* (angles of attack)
angle of attack zero lift : -1.48 ["]
max.angle of attack (stalling angle) : 12.60 ["]
angle of attack at max.speed : 1.71 ["]
calculation : *7* (lift & drag ratios
lift coefficient at angle of attack 0° :0.12 [ ]
lift coefficient at max. angle of attack : 1.14 [ ]
lift coefficient at max.speed : 0.26 [ ]
induced drag coefficient at max.speed : 0.0058 [ ]
drag coefficient at max.speed : 0.0340 [ ]
drag coefficient (zero lift) : 0.0281 [ ]
calculation : *8* (speeds
stalling speed at sea-level (OW): 69 [km/u]
landing speed at sea-level (OW without bombload): 83 [km/hr]
min.drag speed (max endurance) : 108 [km/hr] at 1981 [m](power :42 [%])
min. power speed (max range) : 113 [km/hr] at 1981 [m] (power:44 [%])
max.rate of climb speed : 102.7 [km/hr] at sea-level
cruising speed : 144 [km/hr] op 1981 [m] (power:61 [%])
design speed prop : 152 [km/hr]
maximum speed : 160 [km/hr] op 1981 [m] (power:76 [%])
climbing speed at sea-level (without bombload) : 241 [m/min]
calculation : *9* (regarding various performances)
take-off distance at sea-level : 169 [m]
lift/drag ratio : 10.10 [ ]
max. practical ceiling : 5625 [m] with flying weight :696 [kg]
practical ceiling (operational weight): 4525 [m] with flying weight :845 [kg]
practical ceiling fully loaded (mtow- 1 hour fuel) : 3675 [m] with flying weight :968 [kg]
published ceiling (3962 [m]
climb to 1500m (without bombload) : 7.01 [min]
climb to 3000m (without bombload) : 17.69 [min]
max.dive speed : 381.0 [km/hr] at 2675 [m] height
load factor at max.angle turn 1.87 ["g"]
turn radius at 500m: 47 [m]
time needed for 360* turn 10.9 [seconds] at 500m
calculation *10* (action radius & endurance)
operational endurance : 4.54 [hours] with 2 crew and 77 [kg] useful (bomb)load and 100.0 [%] fuel
published endurance : 4.00 [hours] with 2 crew and possible useful (bomb) load : 93 [kg] and 88.1 [%] fuel
action radius : 462 [km] with 2 crew and 20[kg] photo camera/radio transmitter or bombload
max range theoretically with additional fuel tanks for total 451 [litre] fuel : 1572 [km]
useful load with action-radius 250km : 225 [kg]
production : 32.43 [tonkm/hour]
oil and fuel consumption per tonkm : 1.12 [kg]
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Literature : tussen vleugels van linnen page 56,57
prakt. handb. vliegt. deel 1 page 182
jagdflugzeuge WO I page 38
oorlogsvliegt. 14-18 pages 62 - 66
Jane's FAWOI page 83
bomber 14-39 page 39
gevechtsvliegtuigen 14-18 deel 1 page 59
Bombers 1914-19 page 60,138 (type 9700)
Warplanes WOI page 49,57f,62,67f,68td,70,96,99
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.
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(c) B van der Zalm 04 January 2019 contact : info.aircraftinvestigation@gmail.com python 3.7.2(32-bit)