Breguet AG4

The AG.4(type X) had a 2-spar wing (see Breguet III /U1 for comparison)

Breguet AG.4 (type X)

role : two-seat unarmed reconnaissance

first flight : August 1914 operational : September 1914

country : France

design : Louis Breguet

Nickname : “Whitebait”

Production: 2 prototypes (built in Douai)

General information:

In 1913, Louis Breguet designed and built the only aircraft to be designated Breguet 13 (the first with this designation).Breguet 13 was tested in Reims in September 1913. The test results greatly disappointed both the military and the designer himself and he upgraded the aircraft to a new 160 hp Gnome engine.The last modification was the AG4 aircraft (where the letter A denoted - "Avant", pulling engine, G- engine Gnome, and 4 - the number of modification).

The AG.4 was not a great success, only 2 aircraft were built, but nevertheless it played a crucial role in the beginning of WOI.

At the end of August the Germans moved into France and they approached the Breguet factories in Douai. Breguet flew the just completed AG. 4 (also referred to as Type X) to Paris. The city was preparing itself for the German attack. On the way, the plane lost a piston arm but could be repaired and Breguet offered his services to the French army. On 2 September 1914 Louis Breguet and his observer André Wateau ascended voluntarily for a long-distance reconnaissance mission. During the flight above Germans conquered area northwest of Paris they first saw that Von Kluck was sending his armies to the east and not to the west side of Paris. Their report was handed over to General Joseph Gallieni on 3 September. This report was the starting-up for the Battle of the Marne which led to the stop of the German advance and turn into a retreat. Breguet received the Croix de Guerre for this mission. After that, Aviation Militaire could not but adopt the aircraft. The AG4 was armed with an 8mm Hotchkiss machine gun in the observer's cockpit and with the BR.52 onboard number transferred to the BR17 Squadron. But in October it was lost in the withdrawal of troops.

users : France

crew : 2

armament : no fixed armament

engine : 1 Gnome air-cooled 14 -cylinder atmospheric inlet-valve rotary engine 160 [hp]

(117.7 KW)

dimensions :

wingspan : 15.35 [m], length : 8.25 [m], height : 3.3[m]

wing area : 57.0 [m^2]

weights :

max.take-off weight : 1350 [kg]

empty weight operational : 925 [kg] bombload : 25 [kg]

Andre Wateau, left, and louis Breguet to the right

performance :

maximum speed : 100 [km/hr] at sea-level

climbing speed : 42 [m/min]

service ceiling : 1500 [m]

endurance : 2.5 [hours]

estimated action radius : 112 [km]

description :

2-bay biplane with fixed landing gear with nosewheel and tail strut

two spar upper and lower wing

engines, landing gear, fuel and bombs in or attached to the fuselage

airscrew :

fixed pitch 4 -bladed tractor airscrew with max. efficiency :0.56 [ ]

estimated diameter airscrew 2.86 [m]

angle of attack prop : 11.19 [ ]

fine pitch

reduction : 1.00 [ ]

airscrew revs : 1250 [r.p.m.]

pitch at Max speed 1.33 [m]

blade-tip speed at Vmax and max revs. : 189 [m/s]

calculation : *1* (dimensions)

mean wing chord : 1.86 [m]

calculated wing chord (rounded tips): 2.03 [m]

wing aspect ratio : 8.27 []

estimated gap : 1.98 [m]

gap/chord : 1.07 [ ]

seize (span*length*height) : 418 [m^3]

calculation : *2* (fuel consumption)

oil consumption : 11.8 [kg/hr]

fuel consumption(cruise speed) : 49.2 [kg/hr] (67.1 [litre/hr]) at 80 [%] power

distance flown for 1 kg fuel : 1.83 [km/kg]

estimated total fuel capacity : 190 [litre] (140 [kg])

calculation : *3* (weight)

weight engine(s) dry : 205.9 [kg] = 1.75 [kg/KW]

weight 42 litre oil tank : 3.6 [kg]

oil tank filled with 0.9 litre oil : 0.8 [kg]

Three side drawing of the first AG4

oil in engine 1 litre oil : 0.6 [kg]

fuel in engine 1 litre fuel : 0.6 [kg]

weight 29 litre gravity patrol tank(s) : 4.3 [kg]

weight cowling 4.7 [kg]

weight airscrew(s) (wood) incl. boss & bolts : 41.2 [kg]

total weight propulsion system : 258 [kg](19.1 [%])

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fuselage skeleton (wood gauge : 8.97 [cm]): 170 [kg]

bracing : 9.9 [kg]

fuselage covering ( 12.9 [m2] doped linen fabric) : 4.1 [kg]

weight controls + indicators: 6.7 [kg]

weight seats : 6.0 [kg]

weight other details, lighting set, etc. : 5.1 [kg]

weight bomb storage : 1.8 [kg]

weight 162 [litre] main fuel tank empty : 12.9 [kg]

weight engine mounts & firewalls : 6 [kg]

total weight fuselage : 222 [kg](16.5 [%])

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weight wing covering (doped linen fabric) : 36 [kg]

total weight ribs (59 ribs) : 80 [kg]

load on front upper spar (clmax) per running metre : 920.9 [N]

total weight 8 spars : 124 [kg]

weight wings : 241 [kg]

weight wing/square meter : 4.23 [kg]

weight 8 interplane struts & cabane : 45.8 [kg]

weight cables (88 [m]) : 17.3 [kg] (= 196 [gram] per metre)

diameter cable : 5.7 [mm]

weight fin & rudder (2.7 [m2]) : 12.0 [kg]

weight stabilizer & elevator (6.4 [m2]): 27.5 [kg]

total weight wing surfaces & bracing : 344 [kg] (25.5 [%])

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The second AG.4 BR53 – oktober 1914 at Le Bourget airfield. Has different arrangement of the struts.

weight armament : 0 [kg]

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wheel pressure : 297.0 [kg]

weight 6 wheels (650 [mm] by 76 [mm]) : 32.7 [kg]

weight tailskid : 4.7 [kg]

weight undercarriage with axle 50.1 [kg]

total weight landing gear : 87.6 [kg] (6.5 [%]

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calculated empty weight : 911 [kg](67.5 [%])

weight oil for 3.0 hours flying : 35.3 [kg]

weight automatic pistol with spare magazines : 1.2 [kg]

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calculated operational weight empty : 948 [kg] (70.2 [%])

published operational weight empty : 925 [kg] (68.5 [%])

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| | o | |

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weight crew : 162 [kg]

weight fuel for 2.0 hours flying : 98 [kg]

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Three-view drawing of the 2^nd AG.4. With wingspan 15.35m > chord estimated at 2.01m and wing area estimated at 58m2.

operational weight : 1208 [kg](89.5 [%])

bomb load : 25 [kg]

operational weight bombing mission : 1233 [kg]

weight camera : 20 [kg]

operational weight photo mission : 1228 [kg]

fuel reserve : 41 [kg] enough for 0.84 [hours] flying

possible additional useful load : 80 [kg]

operational weight fully loaded : 1350 [kg] with fuel tank filled for 100 [%]

published maximum take-off weight : 1350 [kg] (100.0 [%])

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calculation : * 4 * (engine power)

power loading (operational without bombload) : 10.27 [kg/kW]

total power : 117.7 [kW] at 1250 [r.p.m]

calculation : *5* (loads)

manoeuvre load : 1.5 [g] at 1000 [m]

limit load : 3.75 [g] ultimate load : 5.6 [g] load factor : 3.1 [g]

design flight time : 2.00 [hours]

design cycles : 800 sorties, design hours : 1600 [hours]

This Breguet also has 2-spar wing, but different hull and tail. Seems to be a combination of the hull of the Gordon-Bennett racer with the wing of the AG4. 1914 type with 110 hp Canton-Unne engine

operational wing loading : 211 [N/m^2]

wing stress (3 g) during operation : 150 [N/kg] at 3g emergency manoeuvre

calculation : *6* (angles of attack)

angle of attack zero lift : -1.16 ["]

max. angle of attack (stalling angle) : 12.12 ["]

angle of attack at max. speed : 3.99 ["]

calculation : *7* (lift & drag ratios

lift coefficient at angle of attack 0° :0.10 [ ]

lift coefficient at max. angle of attack : 1.15 [ ]

lift coefficient at max. speed : 0.44 [ ]

induced drag coefficient at max. speed : 0.0135 [ ]

drag coefficient at max. speed : 0.0877 [ ]

drag coefficient (zero lift) : 0.0742 [ ]

calculation : *8* (speeds

stalling speed at sea-level (OW): 62 [km/u]

landing speed at sea-level (OW without bombload): 74 [km/hr]

The second AG4 was assembled in October and handed over to the military with the onboard number BR.53. It was also armed with a Hotchkiss machine gun and was used as an air defense fighter at Le Bourget airfield. And this car flew for a short time - already in December BR.53 crashed.

min. drag speed (max endurance) = minimum speed*1.1 at cruise height : 71 [km/hr] at 750 [m] (power:54 [%])

min. power speed (max range) : 71 [km/hr] at 750 [m] (power:54 [%])

max. rate of climb speed : 64.4 [km/hr] at sea-level

cruising speed : 90 [km/hr] op 750 [m] (power:75 [%])

design speed prop : 95 [km/hr]

maximum speed : 100 [km/hr] op 100 [m] (power:98 [%])

climbing speed at sea-level (without bombload) : 147 [m/min]

calculation : *9* (regarding various performances)

take-off distance at sea-level : 79 [m]

lift/drag ratio : 7.02 [ ]

max. practical ceiling : 3300 [m] with flying weight :1052 [kg]

practical ceiling (operational weight): 2600 [m] with flying weight :1208 [kg]

practical ceiling fully loaded (mtow- 1 hour fuel) : 2175 [m] with flying weight :1301 [kg]

published ceiling (1500 [m]

climb to 1500m (without bombload) : 12.37 [min]

max. dive speed : 211.0 [km/hr] at 1175 [m] height

load factor at max. angle turn 1.56 ["g"]

turn radius at 500m: 42 [m]

time needed for 360* turn 11.9 [seconds] at 500m

calculation *10* (action radius & endurance)

operational endurance : 2.84 [hours] with 2 crew and 100 [kg] useful (bomb)load and 100.0 [%] fuel

The overall assessment of the aircraft was extremely negative, the design could have saved a more powerful 200-horsepower engine, but Louis Breguet was already engaged in other developments.

published endurance : 2.50 [hours] with 2 crew and possible useful (bomb) load : 117 [kg] and 88.1 [%] fuel

action radius : 201 [km] with 2 crew and 20[kg] photo camera/radio transmitter or bombload

max range theoretically with additional fuel tanks for total 440 [litre] fuel : 590 [km]

useful load with action-radius 250km : 49 [kg]

production : 4.42 [tonkm/hour]

oil and fuel consumption per tonkm : 13.80 [kg]

I_°°=/

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Literature :

praktisch handboek vliegtuigen deel 1 page 91

Jane’s FAWOI page 104

Historische vliegtuigen page 109

Warplanes of World War I page 13

Www.hydroretro.net

http://warnepieces.blogspot.nl/2014/08

http://www.airwar.ru/enc/other1/breguet13.html

Jagdflugzeuge WOI page 7

Oorlogsvliegtuigen 14-18 page 43

Fruhe luftfahrt page 121

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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