The Germans were famous for building diesel airplanes before and during WWII. Jumo engines. Some were quite big.
I wanted to put Zoche or Deltahawk two-stroke diesel in the plane I'm building, but they keep upping the price out of my range.
I'm going to use a Mazda rotary instead.
Jet A is basically kerosene which we know diesel engines will just run fine on.
Current companies looking at offering diesel aircraft engines are:
Zoche
Thiebert
Deltahawk
Continental
I'm sure there are others I am forgetting.