If reciprocating diesels are such a near perfect solution why have they not made greater inroads?
This has perplexed me too. My dad sang the praises of diesels all throughout my growing up years.. he's an engineer (mechanical, thermodynamic) and there's a reason they're used in boats and trucks. The pro's I see of diesels are:
*no electrical needed at all
*can tolerate abusive environment and running at or near full power for long and sustained periods of time
*diesel fuel is much "safer" to work with (much higher flash point, etc.)
*no threat of carb ice
*the higher temps and pressures make for a more thermodynamically efficient combustion cycle
*great low end torque
*can handle a ton of abuse
The cons, for our sport, are
*weight
*weight
*weight
*the diesels I have worked with at least never rann as "smooth" as gasoline engines. Even the brand new Yanmars in the launch boats and the fancy Volvo Penta diesels on multi-million dollar sail yachts were rough. So there would be some vibration issues to overcome with the prop, etc. But Diamond found a way to get over that so clearly it's not impossible and luxury car makers use them too... so it can be done
I think the real answer to that question is much more complicated, and possibly philosophical. And I've always had a hard time buying the argument "if it was such a good idea someone would have done it by now" <- if that logic were true we would never have new inventions. So *why* has it not caught on? I honestly think it all comes down to familiarity and performance ROI
There is a huge familiarity with Lyco and Co with pilots, owners, and mechanics. Our hobby is so expensive as it is that very few people have the financial fortitude to risk being the guinea pigs on a new piece of tech. And, even if money is no object pilots realize their sport has some risks associated with it. Would you rather trust a brand new piece of technology powering your plane, or something that has been around for decades (most people will pick that which has worked for decades). Glass has caught on now, but a lot of people still prefer 6 pack and I remember reading threads back in the early 2000s where people had issues trusting it ("what about total electrical failure, lightning strike, etc. etc."). And frankly I think 90% of the reason glass is common in the GA world is because it looks cool (let's be honest).
I also think that the lack of a real performance advantage means you don't really need to change the wheel. If you really need a performance gain you'll step up to a turbine... otherwise with the options out there right now there is really not some area where a diesel will bring you better speeds or higher useful loads. I think that's the same reason retracts are going out of favor in GA. Sure you may get a couple knots more airspeed (and there's a cool factor to it) but for most people that speed advantage "isn't worth it" until you're up in the 250 knot plus realm. Just look at Diamond's stats for their diesels... you really don't get much for having a diesel engine other than "cool I can burn Jet A" and then you have the looming fear or "what if something breaks, will my mechanic be able to fix it?"
My $0.02 (or whatever's it's worth)
