Dieselgate killed much of the needed emotional support and the slow progress now fears public.
Yes indeed. Retrofits still exist but the numbers are tiny on the scale of general GA engine rework.
Achim is busy flying his TBM850 to and from his business in Egypt so he has found a faster way to burn Jet-A1 
I think it is a pity that retrofit diesels have gone almost nowhere. Socata did a diesel TB20 (using the SMA engine) but had many technical problems with it. Also few would have traded a 250HP Lyco for a 200HP diesel, even though a turbonormalised 200HP diesel would have outperformed the Lyco above a few k feet altitude.
But really it was the pricing which killed the retrofit business. Most people will be attracted (or not) by cost considerations and of a retrofit needs a few hundred hours a year to be worth doing, almost zero private owners and only the wealthiest syndicates will do it.
Even if there is savings to be made due to reduced operational costs which I suspect are marginal at best the high capital outlay must puts most schools off. Also the number of maintainance organisations that have experience with these engines is small so there will be a big learning curve there.
Personally I would like to see the Rotax 915 retrofitted into a PA28-140.
I’m sure there must be something fundamentally wrong with the SMA engine because on paper that would have been a real winner in a Cessna 182 yet Cessna dropped it like a stone.
MedEwok wrote:
But nothing seems to have happened in that regard…
The requirements for power to weight ratio, size and reliability makes a turbine stand out as the obvious/only choice for 99% of aviation. For light GA, manufacturers have to fight against antiquated bureaucracy and a market unable to pay for R&D. It’s a horses for courses kind of thing also. Two stroke diesels (what you are referring to) can be built in many different configurations. They are the only choice for all the worlds large ships for instance (super tankers etc), and these engines are the most efficient engines ever produced. In that niche they are unbeatable, but nowhere else.
A diesel engine in aviation offers the advantage of using widely available and cheap Diesel and/or Jet A1 fuel. There are no other advantages. An engine burning mogas/avgas can always be built with a (much) higher power to weight ratio, more compact and the same reliability.
Also the number of maintainance organisations that have experience with these engines is small
That is a massive understatement, but only some of the downtime stories can be told.
I’m sure there must be something fundamentally wrong with the SMA engine because on paper that would have been a real winner in a Cessna 182 yet Cessna dropped it like a stone.
Indeed, though Cessna sells mostly in the US and there avgas exists freely with no price disadvantages. Also, in the US, you cannot risk getting it wrong. You will be dead and buried if you do. Whereas in Europe you can get it wrong as much as you like and you just send the bill to your customers, with a smile
I would like to see the Rotax 915 retrofitted into a PA28-140
Contrary to popular belief, and millions of forum posts, a Rotax engine doesn’t burn less fuel for the same HP It burns less per HP during climb but for any flight over about half an hour there is no difference.
A diesel engine in aviation offers the advantage of using widely available and cheap Diesel and/or Jet A1 fuel. There are no other advantages. An engine burning mogas/avgas can always be built with a (much) higher power to weight ratio, more compact and the same reliability.
Yes, although a diesel does make more HP per fuel flow, due to the high compression ratio. That is why e.g. a TB20 and a DA42 do the same speed on roughly the same total fuel flow. I suspect the reason why overall there is no advantage is because of the difference in fuel density.
Bathman wrote:
Personally I would like to see the Rotax 915 retrofitted into a PA28-140.
What an utter waste of a 915
Bathman wrote:
I’m sure there must be something fundamentally wrong with the SMA engine because on paper that would have been a real winner in a Cessna 182 yet Cessna dropped it like a stone.
I read about this many years ago (don’t remember where). There were talks about power pulses on that large, low rev, direct drive, 4 stroke engine that no propeller could handle. If it’s true, I don’t know, but it is a plausible explanation.
I think the propeller can handle it but a gearbox can’t, and the SMA engine sidestepped that by, ahem, having no gearbox.
Peter wrote:
Contrary to popular belief, and millions of forum posts, a Rotax engine doesn’t burn less fuel for the same HP
You have to take into account the power to weight ratio and bulkiness. With a Rotax you get a lighter and potentially better streamlined aircraft. This enables less fuel for the same IAS or higher IAS for the same HP, and much better climb.
Jet A at Sywell 77p a litre about 0.85 euros
Jet A France around with euro per litre, last time I bought it (quite a while ago as I usually don’t see the bills when flying the club aircraft).
Diesel from the local garage here in France 1.30 euros until the Macron tax now 1.5euros
Mogas was more than diesel now the same or slightly reversed.
Avgas averages 2.30 euros per litre in this area.
Peter says for his superb TB 20 he gets about the same performance as a DA 42 for the same fuel flow.
DA 42 at 70% averages just less than 40 litres an hour a DA 40 half that.
The maintenance company on our airfield is excellent and diesels make up a large part of his customer base.
The club changed from Robins to a DA 40tdi about 2 years ago and have been surprised with the cost benefits and very happy.
Many other clubs and individuals in Western France are turning to the diesel engine when renewing their fleets or when engines come up for overhaul.
One club did however get an STC for the installation of a Rotax engine, they maitain in house as far as I know and they too are very happy with the cost savings and other clubs are looking at this conversion as a possibility for the future.
Of course there are other costs to be taken into consideration and there is always an argument within clubs when the members debate a change of aircraft.
From a personal point of view I enjoy flying tye DA 40 as much as I did the Robins (well maybe not quite as much but then I did my PPL in various Robins and still have a huge soft spot for them).
I enjoy flying the DA 42 as much or perhaps more than the PA44 the Seneca or maybe even the Aztec, but the Aztec does have great useful load carrying capabilites and STOL performance its also doesn’t suffer greatly from icing.You can also buy a very well equipped, avionics wise, Aztec for a very good price.
The Seneca on the other hand is best for getting elderly parents with knee problems on board.
In other words you pays your money andmyou takes your choice and diesels are the preferred choice for many around here, except for the ULM or experimental market.
DA 42 at 70% averages just less than 40 litres an hour a DA 40 half that.
Not half the fuel flow for the same speed, I am sure. The cockpit volume is the #1 factor in knots per fuel flow, and the two are similar.
