Lets suppose you get to give a single new airplane design and a single prototype
to a participant of World War One. You can offer the Austro-Hungarians the
design for a B-52 if you wish. However, that might prove a manufacturing
challenge to them (and one can only wonder about their supply of jet fuel).

Your goal is to change history. You can hope for a German victory or just that the
Allies win faster. It's up to you.

So, what design do you offer, remembering that this design must be manufactured, fueled,
and armed by the natives?

My first guess, a Fairey Swordfish in 1914 should be buildable and dominate the
skies. The speed, range and bombload would be simply unknown at the time. With a
thousand mile range and a 1,600 lb bomb it would be a great strategic bomber. It
should hold its own even in 1918 though I would not expect the war to last so long.
Again, it's no F-16 but it should be buildable.

Or for a more advanced plane how about a Grumman F-4 without the turbocharger.
I'm not sure the industry of the time was able to build large complex machines of sheet
aluminum, but if so this is a nice plane for world war one.