In contrast to this question (link), I would like to know the opposite - why diesel piston engines aren't used on aircraft with comparable role and configuration to Saab 340, L-410, ATR-42?
There's a very similar question here, but it was mainly focused on small GA aircraft and private owners, while I'm more interested in commuter type piston airplanes.
Here's my thoughts so far after some reading (please note, some of them are just my assumptions and might be wrong).
Pros of diesel engine:
- Engine itself is significantly cheaper
- Cheaper to maintain
- More economical according to this discussion (link)
Cons of diesel engine (vs turbine):
- Likely they are heavier and more bulkier than turbine of similar power output (link to similar discussion)
- Diesel engine pylon is less aerodynamic (more drag) due to presence of necessary air inlets for engine cooling
- Possibly altitude (and thus performance) limited. I'm not really sure about this point though. It's a well-known fact that commuter turboprops can fly at 20-25k feet. I don't have any data for diesel piston engines. I can only assume that diesel engine with a turbo-charger might actually reach similar altitudes and performance.
- Require more frequent maintenance
Perhaps this is worth asking as a separate question.
PW120 EASA data for weight, dimension and thrust (link):
- Length 2130 mm
- Width 635 mm
- Dry weight 417.3 kg
- Take off shaft power 1342 kW
- Maximum Continuous shaft power 1268 kW