That's a lot of development if you insist jets in the 30s were anything like the ones we have now, or even like the ones a few decades ago. By 'early development', I meant that they are comparable to the jets we had when they actually started to become a thing immediately after WWII, when jets were still far from a mastered art. Another thing to keep in mind is that these jets' computer systems are probably very primitive. So they might be comparable to real-life jets, but only if you strip them of all the fancy computer stuff and replace them with very primitive versions.