Wikipedia says that the first turboprop aircraft engine was the Jendrassik Cs-1 invented in Hungary by György Jendrassik.
It says it was supposed to run at 1000 hp but "combustion problems" limited it to 400 hp.
I would like to know what turbine blade alloy it used. Could not find this info online. I have a feeling the blade alloy limits were what limited the engine power, since that is the main limiting factors on gas turbines in general.
Note: The Hungarian version of the wikipedia article says the turbine ran at 550 C, and...
A turbinalapátokat 50% reakciófokú csavart, szárnyprofil keresztmetszetű hőálló acélból gyártották precíziós öntéssel, és speciális beerősítéssel szerelték a rotorba.
The turbine blades are made of 50% reactive twisted, heat-resistant steel with wing section cross-sections, and are specially mounted in the rotor.
Don't know what that means. 50% steel? Then what is the other 50%? Also, there is no citation for it.