Aircraft Avtur Type Fuels
These engines do not burn a "Diesel Fuel". The recent developments are targeted at using Jet A-1, JP-5 or JP-8 as a fuel.
That is the problem, as these aircraft fuels are designed for continuous combustion and do not have a controlled Cetane Index.
Cetane number - Wikipedia, the free encyclopedia
Among other things this shows as a variable ignition delay WRT Crank Angle. The wide range of Cetane Index Nos from various Fuel Suppliers results in a wide spectrum of performance.
Many, many millions have been expended on this over the last 20 or so years. As yet none of these developments has resulted in a truly usable aircraft power-plant.
As aviation gasoline (Avgas) is gradually withdrawn from use and Road Car Fuel (Gasoline) has an ever increasing Alcohol Fraction, more money will be expended in trying to produce a usable small aircraft Avtur power-plant.
Check out what is going on in the UAV world.
A really interesting workspace!
Charlie