Arsenal VB-10

The Arsenal VB-10 was a French heavy fighter designed in 1938 by the engineer Air General Michel Vernisse and assisted by the engineer Badie (hence the initials of the prototype VB). The prototype couldn't be completed before the armistice of 1940.

In 1938 l'Arsenal de l'Aeronautique received an order for a heavy fighter to serve both in the Air Force and the Aéronavale (the French Navy's air arm). So, taking advantage of the 2000hp engines they had available for a civilian trasatlantic airplane (which was the original VG-50 project) that was never materialized, Vernisse had already studied the possibilities of mounting the engines in a tandem configuration having contra-rotating propellers. This idea was accepted for the future heavy fighter which the first prototype, named VG-10, was going to be powered by two 590hp Hispano-Suiza 12X engines, but due to unknown circunstances, the work on that project was abandoned in favour of the VG-20 which looked the very same as the VG-10 but was going to be powered by two 900hp Hispano-Suiza 12Y engines instead. Something interesting to point out about these two projects is that initially they were going to be built out of wood.

Original blueprint for the VG-50

Initially the VB-10 project was presented as a single-seat low-wing monoplane with a conventional retractable landing gear and looking like a conventional single-seat fighter since both engines were in tandem configuration and not mounted in the wings like most of the two-engine airplanes from that era. That particular engine configuration led to the also particular contra-rotating propeller configuration, something never seen. The cockpit was placed between the two engines and the planned armament was pretty impressive, specially for those years as it was expected to be armed with four 20mm cannons and six 7,7mm machine-guns wing-mounted all of them. It promised to be a modern and ambicious fighter made entirelly out of metal, but, given the lack of alluminium in France during the 30s, it was decided to change part of the fuselage to make it out of wood.

The decission of building an airplane made out of non-strategical materials was a major set back for the project and, despite that 40 airplanes were ordered in May 1940, the VB-10 didn't make it to the skies before the armistice. However, during the occupation years, the German RLM (the German ministry of aviation) allowed, in April 1942, the Vichyist authorities to retake the project but the engineer Michel Vernisse was arrested by the Germans for not collaborating and, in addition to that, the original testbed engine was destroyed in an Allied raid at Lyon-Bron airport on 30th April 1944.
Work was retaken in July 1944, just some months before Lyon was liberated (in fact it was liberated on 2n September of that same year) and it wasn't until 7th July 1945 when the original VB-10 made it's maiden flight piloted by Modeste Vonner. It was powered by two Hispano-Suiza 12Y-31 delivering each of them 860hp of power. On December 22 1945, the prototype achieved the respectable speed of 490Km/h and thank to that, the French authorities ordered the production of 200 airplanes.

The second prototype was powered by two Hispano-Suiza 12Z-12/13 delivering each of them 1150hp of power and flown for the first time on 21st September 1946 and was followed by the first production airplane on 3rd November 1947 powered by two Hispano-Suiza 12Z Ars 15/16 engines. However, those engines, built after the war resulted very disappointing as they generated stalls and tend to overheat so the initial order was cut to 50 of them. On 10th January 1948 the second prototype caught fire whilst flying south of Paris. It's pilot, Pierre Decroo, managed to prevent the airplane to crash in an inhabited area before parachuting out, but he was severely burned. On 15th September 1948 the pilot Koechlin perished carbonized on board of the third airplane and that was the last of them to fly as that accident led to the cancellation of the whole project on september 21st and scrapping the existing airplanes (5 in total) and airframes.

Sources:
1. https://fr.wikipedia.org/wiki/Arsenal_VB-10 (translated)
2. https://en.wikipedia.org/wiki/Arsenal_VB_10
3. Salamander Books - The Complete Book of fighters
4. http://www.aerobuzz.fr/culture-aero/article/la-recherche-aeronautique-aux-18e (for the VG-50 civilian trasatlantic airplane)