When it comes to Second World War and Cold War Fighters, if it is French, you know it’s going to be weird. The VB 10 is no different! Work on this Aircraft began in the 1930s, but the project was taken over by the government controlling German-occupied France. This wasn’t enough to kill the project though, and after France’s liberation its development continued.

An innovative and workmanlike design, the VB 10 was a success in the prototyping phase of the project, but after initial enthusiasm led to a big order from the air force the project was cancelled after only a few production airframes were manufactured.

Contents

• Background
• Development
• The VB 10
• Conclusion

Background

The French Air Force had employed locally-produced monoplane fighter aircraft since the 1930s, and new designs were being formulated even as German tanks were rumbling towards Paris, but the capitulation in 1940 brought a pause to French aircraft design and manufacture.

By the conclusion of the Second World War aerial combat had reached a level of lethality and sophistication never before experienced, with both the Allies and Axis air arms fielding piston-engine fighters boasting high speed, heavy armament and good manoeuvrability.

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Despite early jet fighter designs entering active service late in the conflict, development on propeller-driven fighters continued after VE Day in many countries around the world, as the very early jet fighters suffered from many unreliability issues.

Some late-war proposals for new piston-engine fighters were earmarked for further development as a back-up to any potential issues with procuring jet fighters, and some of these designs showcased some very high-performance aircraft indeed.

Some of these experimental and production aircraft include the CAC Kangaroo from Australia, and the F8F Bearcat for the United States Navy, which itself had performance figures superior to many early jet fighters. The French aviation industry also got into the act, with the re-vamping of a pre-war design for a fighter-interceptor that evolved into a post-war fighter program known as the VB 10.

Development

With the prospect of war on the continent looking increasingly likely during the 1930s, the French government established the Arsenal Government Aircraft Factory (Arsenal de l’Aeronautique) at Villacoublay in 1936. In 1937 the factory was given the task of developing a unique twin-engine fighter-interceptor made out of wood, with the power plants situated fore and aft of the cockpit and driving a contra-rotating airscrew.

This design became known as the VG 10, but both it and the improved VG 20 design were abandoned in favour of a re-working of the design utilising an all-metal construction, and this concept became the genesis of the VB 10 program.

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The design for the new aircraft was finalised in early 1940, and an order for production models was authorised, but with the German invasion of Western Europe in May 1940 and the rapid French surrender the program languished until 1942. In that year the Vichy French regime allowed the project to re-start, but progress was glacially slow.

With the project taken over by the new French government after the liberation, a prototype was finally completed and flown for the first time in July 1945 – nearly two months after the conclusion of hostilities in the European theatre of operations.

The two prototypes of the VB 10 were built to different configurations, with the manufacture of the second test aircraft benefiting from operational experience gained during the war.

The first prototype VB 10-01 was unarmed, and the cockpit design blended into the rear fuselage, which obstructed vision to the rear. The airframe was equipped with two 860 hp V12 piston engines powering a contra-rotating propeller assembly, with the rear engine driving the front airscrew, and the front engine powering the rear propeller.

The driveshaft of the rear engine was not able to line up directly with the hub of the front propeller, so a flexible rotating joint allowed power to be delivered safely to the airscrew through the ‘V’ of the front power plant.

Prototype VB 10-02 introduced many improvements in the basic design, with more powerful engines providing 1,150 HP each, and a new bubble canopy similar to that on later marques of Allied fighters.

This airframe was also used to test possible armament fit-outs, and if production models had been armed to the same level the VB 10 would have been the heaviest-armed single-seat fighter ever made.

VB 10-02 first flew on September 1946, and a rigorous test program was initiated using both prototypes and the initial results were promising, but with some power plant problems still needing to be worked out.

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By this stage the French government also had commenced designing and prototyping the first series of jet fighters to be locally manufactured, but the VB 10 project was allowed to continue as insurance against possible delays in jet fighter programs.

The French Air Force had issued an order for 200 VB 10s in December 1945, but this was reduced to 50 units soon after the first flight of a production series airframe in November 1947. This was based on the VB 10-02 prototype with a revised armament fit, but even the reduced number on order were not destined to be delivered as earlier engine issues kept occurring on both the prototypes still in the testing regime.

These recurring mechanical issues included persistent overheating problems, and the second prototype crashed after a rear engine fire in January 1948.

One of the first production aircraft crashed for much the same reason in September 1948, resulting in the death of the pilot. By this stage the French Air Force and the government had had enough, and the VB 10 project was cancelled six days after the second crash involving the type.

This decision was taken because enough surplus Allied fighter planes were available to equip French fighter units in the immediate post-war period, and these aircraft were deemed adequate – and cost-effective – until the first French jet designs appeared in the late 1940s.

Only four production aircraft were completed before manufacturing of the VB 10 ceased, and any surviving airframes were scrapped after the jet age became entrenched.

The VB 10

The use of two in-line engines in a single fuselage ensured that the VB 10 concept ended up as one of the biggest – and heaviest – single-seat monoplane propeller fighters ever made. In size, the airframe dwarfed even the massive P-47 Thunderbolt, and the loaded weight of the VB 10 exceeded that of an empty modern F-16 combat fighter.

Despite this great size and weight, the VB 10 was a surprisingly nimble aircraft, with respectable performance figures.

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The VB 10 had a height of 5.2 metres (17 feet 1 inch), a length of 12.98 metres (42 feet 7 inches) and a wingspan of 15.49 metres (50 feet 10 inches). Empty the VB 10 tipped the scales at a hefty 6,230 kilograms (13,735 pounds), and the gross loaded mass of the airframe was an impressive 9,523 kilograms (20,995 pounds).
The aircraft was powered by two Hispano-Suiza 12Zars V12 liquid-cooled piston engines, with the cockpit being flanked by an engine each side in the fuselage.

These power plants developed 1,150 HP each, and drove a twin three-blade contra-rotating airscrew which was enough to propel the VB 10 at a top speed of 700 km/h (430 mph). The combat range of the aircraft was a respectable 1,700 kilometres (1,100 miles), and the ferry range was an impressive 2,600 kilometres (1,600 miles), comparable to that of some multi-engine bombers of the war period.

The service ceiling of the VB 10 was 11,000 metres (36,000 feet), as required for its role as a high-altitude interceptor.

All dimension and performance data is given for the second prototype, VB 10-02.

The second prototype was very heavily armed; four 20mm Hispano-Suiza HS.404 autocannon with 150 rounds per gun, and six .50 calibre M2 Browning heavy machine guns, with 600 rounds supplied for each gun.

While production aircraft were envisaged to have a different armament fit consisting of either cannon or heavy machine guns, the second prototype must go down as one of the most heavily armed fighters of the period.

With that amount for firepower available, enemy air and ground targets would not just have been destroyed, they may have been completely atomised! The VB 10 was also capable of carrying four air-to-ground rockets under the outer underside of each wing, and could carry a bombload of 1,100 kilograms (2,500 pounds) on inner under-wing pylons.

Conclusion

The Arsenal VB 10 was an impressive design with some innovative design features and respectable performance figures, but suffered the fate of similar late-war designs for high-performance piston fighters.

Despite some advantages over early jet designs in the sphere of reliability, and having performance figures that rivalled some early jet aircraft of the post-war era the writing was on the wall for the piston-powered aerial fighters in general, and the new jet fighter sounded the death-knell for many fine designs of propeller-driven fighters.

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As such, the VB 10 ends up as an interesting footnote in the story of piston-engine fighters, and a fascinating chapter in French aviation history.

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