a $300k TP engine (as compared with a $50k IO540 etc)
Stupid question, but why needs a TP engine needs to cost 6x more money than a piston?
From what I understood the technique behind a TP is a lot simpler than a piston engine. Less moving parts, etc.
I’m impressed by the earlier mentioned AI-450M1. It weights only 115KG, yet it delivers 465HP. That’s really amazing :)
A Lyco/Conti piston engine is low tech made from cheap materials with large tolerances in manufacturing and assembly. A turbine uses very expensive alloys and has very small tolerances. Also the market is extremely small with low quantities.
Eastern Europe has some nice and affordable turbines. Especially Russian companies have a lot of experience with titanium and it used to be a much more popular metal than in the West. I have a Russian made boat which uses titanium bolts and parts, very strange for somebody from the West.
The reason is in the much smaller tolerances and the material. Compared to a turbin a piston engine is some metal junk flying in close formation :-)
In the day and age of CAD, 3D printing, computer-driven machining etc. etc. “close tolerances” ought to be a given…
There is no point to have a turboprop without pressurisation as ideal conditions for a TP is FL250+.
What about Twin Otter, L410, Do.228, EMB110 and many other aircraft in that class?
Eastern Europe has some nice and affordable turbines. Especially Russian companies have a lot of experience with titanium and it used to be a much more popular metal than in the West. I have a Russian made boat which uses titanium bolts and parts, very strange for somebody from the West.
The smallest turboprop engine made in Russia is TVD-20 (1375 hp) with the TBO of only 2000 hours. Сonsiderably more industry experience has been accumulated in Ukraine (Motor Sich / Ivchenko-Progress – that’s where AI-450M comes from), and still more in Czech Republic (Walter, a.k.a. GE Aviation Czech, and PBS).
It’s not as simple as it seems … I have a friend who worked with Rolls Royce, developing Airbus engines. He would give me long lectures about the required precision. An aircraft turbine has to stay WITHIN very small tolerances in a wide range of temperature and pressure scenarios. If there was a way to make a simple cheap turbine … it would have been done.
Other than that it really doesn’t make much sense to fly a turbine in FL100. Of course there’s nice on which you ca fly above the weather at FL100. But the turbine is too thirsty at these altitueds and the air still too dense to really take advantage of all that power. In the end people will rather buy a used Jetprop or Meridian.
Other than that it really doesn’t make much sense to fly a turbine in FL100
Why not?
It does not make sense to have a piston engine without a turbocharger (the instant you get airborne you are losing power) and when you have a turbo, it does not make sense to fly below FL200. So, the entire non-turbo piston engine business is just rubbish. Yet, people (like me) do buy the stuff 
In the end people will rather buy a used Jetprop or Meridian.
I have always said that in the past (i.e. the ready availability of good used TP aircraft prevents a new player entering the market) but there are lots of people who buy a brand new fully loaded SR22 for $750k or so, and buy the latest model 2 years later, and so on. There does seem to be a different market for brand new stuff with all the latest gizmos. A Jetprop is really nice and hugely mission-capable but it is still a 30 year old plane.
I do think that a fixed gear turboprop tourer like this Diamond one is going too far in marketing cynicism… The salesman whose job will be to justify fixed gear with a TP engine is going to get a medal. I assume it has a parachute!
I have a friend who worked with Rolls Royce, developing Airbus engines. He would give me long lectures about the required precision.
They’d better. RR does not exactly have a spotless record in terms of what their engines can do…. QF32 comes to mind and the A330 accident where both engines were ruined but thankfully one kept going
Two oil fire accidents with very similar outcome (The A330 wing looked pretty much like the A380 wing at Singapore) should catch their attention I reckon….
An aircraft turbine has to stay WITHIN very small tolerances in a wide range of temperature and pressure scenarios.
Depends on the turbine. Some have very narrow operating ranges, others are much more robust. Russian power plants, while not the most economic in the world, have quite a history in that, some of it achieved by balantly “forgetting” about TBO’s and maintenance but these turboprops and some of their jets still soldier on until they break quite spectacularly mostly with 3rd world outfits. While it looks bad in the papers, when you look at the actual figures you can’t but admire the enigneering behind them, which allows these engines to often reach twice or three times the recommended TBO before the engines finally come apart.
With that in mind I have not a bad feeling about this choice of engine by Diamond. If it can survive under the operating conditions it does, it may well be a pretty good choice to put on a GA plane.
Turboprop is a whole new level of coolness In some places and for some missions reliability and availability are more important than efficiency. Or to put it in other words; efficiency without the required reliability/availability is not worth much, due to the cost (in some way) of unplanned downtime. Such a mission is not the typical private fly for pleasure mission, but either a commercial or governmental thing. For instance, crop spraying is done by turboprops nowadays. This would never happen if it was more economical with piston power. Lifting skydivers is also done just as efficiently with turboprop (if there are enough skydivers).
What that TP DA50 is going to be used for, I have no idea though.
Why do I not feel like justifying what an expert turbine engine engineer explained to me? ;-) I think Rolls Royce builds great Jet engines, and you really cannot take a couple of isolated isolated incidents and critisize a company like that.
Peter, the main reason, for me, would be that I am not going to spend 1.3 millions Euros on a TP plane that cannot REALLY outclimb weather and has no pressurized cabin.
Of course a non-turbo piston aircraft like mine or yours is a compromise. But actually I like a € 220.000 better than a € 1.000.000 compromise. I woud not buy a € 750.000 SR22 (it’s € not $ now) – but I will buy the used ones later ! I will actually never buy a € 750.000 airplane, no matter what it is.
