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Sopwith 7F.1 Snipe
role : fighter
first flight : early 1918 operational : September 1918
country : United-Kingdom
design : Herbert Smith
production : 1500 aircraft
general information :
The Snipe was designed to succeed the Sopwith Camel. The new 169 KW Bentley B.R.2 rotary engine was installed. The design phylosophy was the same as for the Camel.
The upperwing had a large opening for better view. It proved itself in combat as being highly agile and strong. The rate of climb was high but it was not as fast as the SPAD S.XIII or the RAF SE5a. After WWI it became the standard RAF fighter and remained in service till 1927.
Gap : 1.30m chord : 1.52 m fuel : 175 litre oil : 31.8 litre > enough for 3 hrs flightThe first squadron to equip with the new fighter was No. 43 Squadron, based at Fienvillers in France, which replaced its Camels with 15 Snipes on 30 August 1918. One of the most famous incidents in which the Snipe was involved occurred on 27 October 1918 when Canadian Major William G. Barker attached to No. 201 Squadron RAF flew over the Foręt de Mormal in France. Barker's Snipe (No. E8102) had been brought with him for personal evaluation purposes in connection with his UK-based training duties and was therefore operationally a "one-off". The engagement with enemy aircraft occurred at the end of a two-week posting to renew his combat experience as Barker was returning to the UK. While on his last operation over the battlefields of France, Major Barker attacked a two-seater German aircraft and swiftly shot it down. However, Barker was soon attacked by a formation of at least 15 Fokker D.VIIs, an aircraft widely considered to be the ultimate German fighter design of the First World War. The ensuing melee was observed by many Allied troops. In the engagement, Barker was wounded three times, twice losing consciousness momentarily, but managing to shoot down at least three D.VIIs before making a forced landing on the Allied front lines. Barker was awarded the Victoria Cross for this action.[15][16] The fuselage of this Snipe is preserved at the Canadian War Museum, Ottawa, Ontario.[14]
users : RAF
crew : 1
armament : 2 synchronized 7.70 [mm] (0.303 in) Vickers machine-guns
engine : 1 Bentley B.R.2 air-cooled 9 -cylinder two-valve rotary engine 230 [hp](169.2 KW)
dimensions :
wingspan : 9.14 [m], length : 5.84 [m], height : 2.89[m]
wing area : 23.78 [m^2]
weights :
max.take-off weight : 916 [kg]
empty weight operational : 596 [kg] bombload : 36 [kg]
performance :
maximum speed : 195 [km/u] op 3048 [m]
climbing speed : 383 [m/min]
service ceiling : 5944 [m]
endurance : 3.01 [hours]
estimated action radius : 264 [km]
description :
2-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 :0.67 [ ]
estimated diameter airscrew 2.58 [m]
angle of attack prop : 23.16 [ ]
reduction : 1.00 [ ]
airscrew revs : 1250 [r.p.m.]
pitch at Max speed 2.60 [m]
blade-tip speed at Vmax and max revs. : 177 [m/s]
calculation : *1* (dimensions)
mean wing chord : 1.30 [m]
calculated wing chord (rounded tips): 1.46 [m]
wing aspect ratio : 7.03 []
gap : 1.30 [m]
gap/chord : 1.00 [ ]
seize (span*length*height) : 154 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 7.4 [kg/hr]
fuel consumption(cruise speed) : 37.4 [kg/hr] (51.1 [litre/hr]) at 55 [%] power
distance flown for 1 kg fuel : 4.69 [km/kg]
estimated total fuel capacity : 174 [litre] (128 [kg])
calculation : *3* (weight)
weight engine(s) dry : 220.0 [kg] = 1.30 [kg/KW]
weight 34 litre oil tank : 2.9 [kg]
oil tank filled with 1.3 litre oil : 1.1 [kg]
oil in engine 1 litre oil : 0.8 [kg]
fuel in engine 1 litre fuel : 0.8 [kg]
weight 22 litre gravity patrol tank(s) : 3.3 [kg]
weight self-starter : 4.1 [kg]
weight cowling 6.8 [kg]
weight airscrew(s) (wood) incl. boss & bolts : 25.4 [kg]
total weight propulsion system : 262 [kg](28.6 [%])
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fuselage skeleton (wood gauge : 6.19 [cm]): 57 [kg]
bracing : 2.4 [kg]
fuselage covering ( 6.4 [m2] doped linen fabric) : 2.1 [kg]
weight controls + indicators: 5.3 [kg]
weight seats : 3.0 [kg]
weight other details, lighting set, etc. : 5.1 [kg]
weight bomb storage : 2.5 [kg]
weight 153 [litre] main fuel tank empty : 12.2 [kg]
weight engine mounts & firewalls : 8 [kg]
total weight fuselage : 98 [kg](10.7 [%])
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weight wing covering (doped linen fabric) : 15 [kg]
total weight ribs (58 ribs) : 54 [kg]
load on front upper spar (clmax) per running metre : 834.2 [N]
load on rear upper spar (vmax) per running metre : 291.4 [N]
total weight 8 spars : 40 [kg]
weight wings : 110 [kg]
weight wing/square meter : 4.61 [kg]
weight 8 interplane struts & cabane : 9.5 [kg]
weight cables (55 [m]) : 3.5 [kg] (= 63 [gram] per metre)
diameter cable : 3.2 [mm]
weight fin & rudder (1.0 [m2]) : 4.6 [kg]
weight stabilizer & elevator (2.7 [m2]): 12.5 [kg]
total weight wing surfaces & bracing : 140 [kg] (15.3 [%])
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weight machine-gun(s) : 31.8 [kg]
weight ammunition magazine(s) :2.7 [kg]
weight synchronizing system : 2.0 [kg]
weight Aldis gunsight : 0.8 [kg]
weight armament : 37 [kg]
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wheel pressure : 458.0 [kg]
weight 2 wheels (700 [mm] by 78 [mm]) : 19.8 [kg]
weight tailskid : 4.2 [kg]
weight undercarriage with axle 21.2 [kg]
total weight landing gear : 45.2 [kg] (4.9 [%]
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calculated empty weight : 583 [kg](63.6 [%])
weight oil for 3.6 hours flying : 26.9 [kg]
weight ammunition (800 rounds) : 27.2 [kg]
weight Very pistol with cartridges : 3.6 [kg]
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calculated operational weight empty : 641 [kg] (69.9 [%])
published operational weight empty : 596 [kg] (65.1 [%])
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weight crew : 81 [kg]
weight fuel for 1.5 hours flying : 56 [kg]
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operational weight : 778 [kg](84.9 [%])
bomb load : 36 [kg]
operational weight bombing mission : 814 [kg]
fuel reserve : 72 [kg] enough for 1.92 [hours] flying
possible additional useful load : 31 [kg]
operational weight fully loaded : 916 [kg] with fuel tank filled for 100 [%]
published maximum take-off weight : 916 [kg] (100.0 [%])
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calculation : * 4 * (engine power)
power loading (operational without bombload) : 4.60 [kg/kW]
total power : 169.2 [kW] at 1250 [r.p.m]
calculation : *5* (loads)
manoeuvre load : 3.7 [g] at 1000 [m]
limit load : 4.5 [g] ultimate load : 6.8 [g] load factor : 2.1 [g]
design flight time : 2.41 [hours]
design cycles : 249 sorties, design hours : 600 [hours]
operational wing loading : 321 [N/m^2]
wing stress (3 g) during operation : 209 [N/kg] at 3g emergency manoeuvre
calculation : *6* (angles of attack)
angle of attack zero lift : -1.45 ["]
max.angle of attack (stalling angle) : 12.39 ["]
angle of attack at max.speed : 1.47 ["]
calculation : *7* (lift & drag ratios
lift coefficient at angle of attack 0° :0.12 [ ]
lift coefficient at max. angle of attack : 1.15 [ ]
lift coefficient at max.speed : 0.24 [ ]
induced drag coefficient at max.speed : 0.0047 [ ]
drag coefficient at max.speed : 0.0409 [ ]
drag coefficient (zero lift) : 0.0362 [ ]
calculation : *8* (speeds
stalling speed at sea-level (OW): 77 [km/u]
landing speed at sea-level (OW without bombload): 92 [km/hr]
min.drag speed (max endurance) : 117 [km/hr] at 3048 [m](power :28 [%])
min. power speed (max range) : 126 [km/hr] at 3048 [m] (power:29 [%])
max.rate of climb speed : 122.0 [km/hr] at sea-level
cruising speed : 176 [km/hr] op 3048 [m] (power:48 [%])
design speed prop : 189 [km/hr]
maximum speed : 195 [km/hr] op 3048 [m] (power:62 [%])
climbing speed at sea-level (without bombload) : 545 [m/min]
calculation : *9* (regarding various performances)
take-off distance at sea-level : 136 [m]
lift/drag ratio : 9.26 [ ]
max. practical ceiling : 6325 [m] with flying weight :709 [kg]
practical ceiling (operational weight): 5950 [m] with flying weight :778 [kg]
practical ceiling fully loaded (mtow- 1 hour fuel) : 5425 [m] with flying weight :879 [kg]
published ceiling (5944 [m]
climb to 1500m (without bombload) : 3.05 [min]
climb to 3000m (without bombload) : 7.34 [min]
max.dive speed : 442.2 [km/hr] at 4425 [m] height
load factor at max.angle turn 2.78 ["g"]
turn radius at 500m: 52 [m]
time needed for 360* turn 9.0 [seconds] at 500m
calculation *10* (action radius & endurance)
operational endurance : 3.42 [hours] with 1 crew and 67 [kg] useful (bomb)load and 100.0 [%] fuel
published endurance : 3.01 [hours] with 1 crew and possible useful (bomb) load : 82 [kg] and 88.1 [%] fuel
action radius : 409 [km] with 1 crew and 20[kg] photo camera/radio transmitter or bombload
max range theoretically with additional fuel tanks for total 307 [litre] fuel : 1056 [km]
useful load with action-radius 250km : 119 [kg]
production : 20.82 [tonkm/hour]
oil and fuel consumption per tonkm : 2.16 [kg]
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Literature :
Jane's FAWOI page 86
prakt. handb. vliegt. deel 1 page 208,209
Warplanes WW1 page 156f
Fighters 1914-19 page 75
Groten van het luchtruim page 57
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)