Some of the early postwar French projects were so unconventional that I've always suspected that they were intended more to keep the industry occupied as it was reassembled and soak up Marshall Plan funds than to produce service-ready designs.
Mostly right (although disagreeing on marshall funds). In 1946 France had a communist aviation minister, Charles Tillon, not a bad man per se and who did his best to restart the aircraft industry at any cost - including vanity projects and ramping up production out of a ruined industry. He just went a bridge too far.
en.wikipedia.org
The reality of the time however was (somewhat ironically) large scale production of German aircraft build under licence by Vichy France - they were continued after 1944. Problem was, they had been duly sabotaged by the resistance... and now this turned against post-war France. Still Tillon wanted 4000 aircraft by 1946-47.
Most of the German aircraft were trainers and transports and utility, with the notable exception of FW-190. It could have provided a decent combat aircraft but not only reliability was catastrophic, but they issued these birds to the... Normandie Niemen (Neu-Neu) squadron, who had fought these very FW with their Yak-9s now worn out (and paid a heavy death toll to the Germans).
Imagine the Neu-Neu pilots faces when they were told "you will trade your Yakovlev against FW."
As for the War in Indochina beginnings, in 1946 the Armée de l'Air had to scavenge Japanese Ki-43 aircraft before getting Spitfires (1947, wholly inadapted), P-63s (hardly better) and finally, Bearcats (at least, but by 1950 the game was already over).
http://worldatwar.net/chandelle/v3/v3n1/frcoin.html
A major issue was the engines - pre-war french designs were obsolete and
twice unreliable (1939 reliability was already pretty bad, 1945 did not helped) while german engines, too, got twin pains - late-war Germany low quality plus resistance sabotages.
A boatload of crashes happened as a result.
Meanwhile research on jet engines started unabated but it took time. Plus all the delays suffered by 4 years of occupation did not helped. What's worse, jet engines soon pushed toward the sound barrier and it was already a bloody and tedious affair for GB, USA and USSR - so imagine for France. Although the Espadon, by pure luck, was not a killer like the VG-90, it just climbed like a led brick because it was too heavy. So Vampire, Mistral and Ouragans kicked it out.
It is interesting to compare the fate of the first three jet fighters - Espadon, Vampire-Mistral and Ouragan.