Ultranomad wrote:
it mandated a removal of the “TURBO” decal from the cowling
And it really looks ugly on the cowling, where you can see the “TURBO” pasted over with a colored something so that it shall look as if it never was there. Now it’s only left “charged”, but the word is misaligned of course.
In principle it’s anectodical. However as the AD is still valid and active I may not return to the initial state. It’s from the very early beginning when the first turbochargers were introduced back in 1970 to ’72. No one knew that such turbochargers existed.
A Lycosaur has good efficiency at one single point of rpm and load, and it requires careful fiddling by the pilot at that point to achieve OK efficiency. The 912 iS is optimized for all loads and rpms and achieves good efficiency every time without the pilot having to do a single thing. In practice they are not comparable. The 912 iS is far ahead.
The Lycoming has the same or better efficiency at any point under 75% power, which is the maximum power setting at which it can be leaned. The engine is operated over 75% power for about 5-10 minutes at the beginning of a typical flight. For example, here was my last flight on Saturday (coming home from a fly to lunch flight in my $35K aircraft).
The trade off for the benefit at the beginning of every flight (and also if the pilot is incompetent or distracted) is that the 912iS or similar engines need active liquid cooling to allow power settings over 75% with lean mixture, and have a bunch of failure prone electronics to do what the pilot does on the Lycoming. It’s reasonable to choose either based on the buyers priorities and they are directly comparable. Personally l prefer to spend my money on things that are sustainable and also drive a manual shift car every day 
Because the labor cost of overhaul highly exceeds the labor cost of building new engine and any savings accomplished with reusing used parts on overhauled engine is just a peanuts and can’t cover this difference.
Which is a function of the engine design priorities, in this case accepting a disposable engine in order to reduce production cost and increase profit. The downside is the entire aircraft being dependent on the supply of new engines from the manufacturer to maintain airworthiness over the coming decades, not just engine parts which would otherwise be available from multiple other suppliers under PMA. That’s a good situation if you are selling engines, not so good if you own the plane.
I’m very familiar with the development of a direct competitor to these Diesel engines that is now flying and being sold to the customer. The trade-offs were the same. I wouldn’t want one on my own plane because these trade-offs don’t suit my needs.
Silvaire wrote:
Which is a function of the engine design priorities, in this case accepting a disposable engine in order to reduce production cost and increase profit.
Unfortunately Diamond aircraft owners that bought planes with Austro relied on DAI’s promise on low overhaul cost (€18k was stated price in 2010) which turned out to be not so low (€23k in 2015, €30k 2018, €36k in 2020) which in the end turned to TBR in 2022 at €50k.
Fairy tales still can be found at DAI web site.
Their US representatives followed the story.
Yet the owners are still happy regardless many MSB putting dozens of aircrafts on ground for many months due to many engine problems.
Emir wrote:
Unfortunately Diamond aircraft owners that bought planes with Austro relied on DAI’s promise on low overhaul cost (€18k was stated price in 2010) which turned out to be not so low (€23k in 2015, €30k 2018, €36k in 2020) which in the end turned to TBR in 2022 at €50k.
Emir, is there any link to the source for the TBR? My assumption was always that Austro engines are TBO, with gradually reducing count of timed parts.
Thanks!
arj1 wrote:
Emir, is there any link to the source for the TBR? My assumption was always that Austro engines are TBO, with gradually reducing count of timed parts.
Thanks!
Emir wrote:
Austro_engine_TBR_pdf
50K per engine? That is a bit steep… They are getting more and more expensive and not that interesting anymore…
arj1 wrote:
50K per engine? That is a bit steep… They are getting more and more expensive and not that interesting anymore…
CD-155 is approximately the same or a bit more but at least I knew from the very beginning it was TBR.
Diamonds are very popular in flight training academies where such costs are easily amortized at 1000 hours of utilization annually.
For private owners of 42/62 the alternative is a Cirrus with similar overhaul costs.
Peter
19-Feb-24 10:56
42
It’s not the gap; it is small scale effects versus large scale effects of gas flow… I think it is viscosity which dominates in small scales and buggers up the efficiency. Same reason why small propellers (as on e.g. quadcopters) are inefficient. Hence centrifugal compressors rather than axial compressors in small turbines. And there is another factor, discovered recently by developers of small turbines: blade erosion is relatively a much bigger thing in a small engine, because the blades are so thin.
The big propeller Vs the little propeller efficiency thing is a bit more fundamental than any scale effect.
Think about it. To produce thrust we accelerate a working fluid. In the casyof the propeller it’s air.
Mr. Newton said that for every action there is an equal and opposite reaction.
We express this as MV=MV.
With the small propeller we have less M to we need more v.
The problem that arises is that the energy required to do this raises as the square of the velocity. In a perfect world, from the prop efficiency point of view, we’d have huge props and undercarriages like storks.
To take it to extremes, compare the fuel burn of a harrier in the hover with a helicopter of comparable weight.
Joe_90 wrote:
To take it to extremes, compare the fuel burn of a harrier in the hover with a helicopter of comparable weight.
I see where you are going but I’m sorry, I don’t have access to these numbers :D. Could you lighten up our minds (mine at least)?
