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Single-Engine, Twin-Seat Fighter Prototype

Just two prototypes made up the BAJ Type IV venture - and little information on the design exists today.
Authored By: Staff Writer | Last Edited: 1/16/2019
With the end of World War 1 (1914-1918) still not a foregone conclusion in early 1918, the French Air Force continued to entertain all-new fighter designs. The B.A.J. ("Boncourt-Audenis-Jacob" of Bron, France) "Type IV" was one of the late-war entries that appeared during this time and comprised a single-engine, tandem twin-seat fighter with biplane wing configuration. However, its arrival towards the end of the war and delays during its development meant that only two prototypes were ever completed. Design of this biplane was attributed to Charles Audenis.

As with other aircraft of this period, the two seat arrangement of the Type IV had the pilot in the forward cockpit with the observer/gunner in the rear (seated back-to-back in close proximity to one another). Armament was a single, fixed, forward-firing 7.7mm Vickers Machine Gun synchronized to fire through the spinning propeller blade by the pilot and twin 7.7mm Lewis Machine Guns on a trainable mounting (T.O.3 series ring) for the rear gunner.

The fuselage was left relatively clean by the standards of the day and even the engine was shrouded over for aerodynamic efficiency. Power was pulled from a single Hispano-Suiza 8Fb 8-cylinder, water-cooled inline piston engine of 300 horsepower, this used to drive a two-bladed, fixed-pitch wooden propeller at the nose.

The biplane configuration utilized a traditional "over-under" wing arrangement of equal span and twin-bay. The interplane support struts were single pieces and cabling was used where necessary. The mainplanes were seated well-forward of midships. The tail unit was given small-area planes itself, a single vertical fin and low-set horizontal planes. The undercarriage was also traditional for the time, made up of a fixed twin-wheeled main unit under center mass and a tailskid at rear.

French authorities though enough of the Type IV design that it contracted for the aircraft on May 1st, 1918. However, the initial prototype was not delivered to Villacoublay for formal evaluations until November of that year due to requested revisions (to be handled by Hanriot) and the official Armistice to end hostilities was signed that November 18th. After a fire broke out at the Bron facility, work on the airplane was not completed until January of 1919. Trials then followed which led to additional repairs seen during the middle part of the year. By this time, a second prototype was being flown for evaluation but the project was more or less a lost cause - the war was over and any additional development of the Type IV was ended with just the two prototypes to show for the effort.

As no specifications exist on this aircraft today, estimates for this entry have been made by the author.


[ 2 Units ] :
Boncourt-Audenis-Jacob (BAJ - France
National flag of France France (cancelled)
- Fighter
- Reconnaissance (RECCE)
- X-Plane / Developmental
65.62 ft (20 m)
85.30 ft (26 m)
26.25 ft (8 m)
(Showcased structural dimension values pertain to the BAJ Type IVC.2 production model)
Empty Weight:
992 lb (450 kg)
1,323 lb (600 kg)
(Diff: +331lb)
(Showcased weight values pertain to the BAJ Type IVC.2 production model)
1 x Hispano-Suiza 8Fb 8-cylinder water-cooled inline piston engine developing 300 horsepower and driving a two-bladed, fixed-pitch wooden propeller at the nose.
(Showcased powerplant information pertains to the BAJ Type IVC.2 production model)
Maximum Speed:
121 mph (195 kph; 105 kts)
Service Ceiling:
17,060 feet (5,200 m; 3.23 miles)
Maximum Range:
199 miles (320 km; 173 nm)
850 ft/min (259 m/min)
(Showcased performance values pertain to the BAJ Type IVC.2 production model; Compare this aircraft entry against any other in our database)
1 x 7.7mm Vickers Machine Gun in fixed, forward-firing mounting.
2 x 7.7mm Lewis Machine Guns in rear, trainable gunner's position.
(Showcased armament details pertain to the BAJ Type IVC.2 production model)
Type IV - Base Series Designation.
Type IVC.2 - Prototype designation; two completed.

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