Diamond DA42V1

[Mickey Kaye]

I read on the net that Delta Hawk were gearing up for certified production.

Aero-TV: Radical Upgrades -- LoPresti Reinvents the SR20 - YouTube

Is a link which shows lopresti designing an improved engine cowling for the cirrus.

[achimha]

So, in Europe, take out the reliance on avgas and what have you got? A bet on future tax policy...

The tax situation is different in each EU country. However, I don't think it is a major factor. Avgas is getting rare (outside Northern Europe) and getting more and more expensive due to the very small production volume and separate infrastructure. An unleaded replacement would suffer from the same economics of scale issue in Europe (I bet a busy gas station in the UK sells more petrol a day than all airports in the country sell avgas on an average day). What makes things even worse, the avgas burning portion of GA keeps shrinking in Europe. The Rotax powered fleet tend to use 98 octane mogas. Unfortunately the EU now requires the oil companies to add up to 10% ethanol which the Rotax engines/fuel systems are not certified for so aerodromes have to determine the ethanol concentration for each fuel delivery.

I don't see any real alternative to diesel piston engines outside of the US. I read that the companies that built the skyscrapers in Manhattan all went bust. The ones that bought the towers at a bargain price became very rich.

[Jan Olieslagers]

I read on the net that Delta Hawk were gearing up for certified production.

Yes, so did I. Can't count the years anymore, though.

[A and C]

Jan

I was thinking the same thing myself and was rather looking forward to more news about the Deltahawk project.

[27/09]

peterh337

I also think that the current diesel retrofit options are priced right at the very top of what is perceived anybody anywhere might possibly pay, with the "anybody anywhere" being the busy flying school business model. This doesn't exactly help wide adoption.

So far as the adoption of "new" technology or a "new" product is concerned the price is the real problem. If you look elsewhere the introduction of a new product which is also very often an unknown quantity/quality is usually done at a price point that mitigates the risk to the purchaser. Take Hyundai, their cars were cheap to start with. Sure they may have been a little "nasty" but with time they have established a good reputation and now command a price accordingly.

The retro fit price means no one is going to retrofit plus the issues that have been experienced with even the OEM diesel engines means not many will want to bother with them even as new. There's one DA42 operator here that spec'd their DA42's with the Lycoming engines, (I think they were the first purchaser of the Lycoming variant) they would have had to have rocks in their head to go the diesel way.

achimha

I don't see any real alternative to diesel piston engines outside of the US.

Perhaps you should say "I dont' see any real alternative to diesel engines in Europe"
Because for the majority of the GA world (US, Canada, South Africa, Australia, New Zealand) outside of Europe, avgas isn't a problem.

achimha

I read that the companies that built the skyscrapers in Manhattan all went bust. The ones that bought the towers at a bargain price became very rich.

Are you trying to say the companies developing the diesel engine may go broke but the companies that come along and buy them up will make a fortune. If so I have to disagree. The skyscrapers didn't need ongoing development and warranty support like the engines will.

Where I see future potential is in small turbines. It's already proven technology, they are very reliable and light weight. Much of the development is taking place already with turbines used in other areas be it aviation or industry. It's a matter of getting the costs down and the ground idle fuel consumption down to lower levels.

[peterh337]

Turbine SFC is poor however, currently, with little improvement on the horizon.

Especially small ones.

They just about make sense at FL200+ due to the TAS gain, which practically implies pressurisation, e.g. a Jetprop or similar, and even then you are looking at 2x the fuel burn of a piston engine for the same airframe (PA46).

They are also very very expensive, with little prospect of this changing.

You are right about avgas. For all the gloom in the press, it continues to be available all over the world, and where it has disappeared its demise seems to have been driven by the usual European idiotic airport management rather than a lack of availability. The AIR BP booklet shows avgas available in some suprising places, with some African countries (I don't mean RSA) having loads of outlets. It is this wide availability which makes me optimistic about its long term future - albeit at a constantly rising price in Europe.

[goldeneaglepilot]

So a typical fuel burn of 34gall per hour is double? Typical fuel burn for an IO540 PA46 is 24 gallons per hour (I know from first hand experience). Plus an initial climb rate of 3000ft per minute in the Jetprop rather than 1300ft / min in the piston variant.

Using December 2011 Birmingham UK fuel prices that works out at approximatly £0.91 / L for Jet A1 and £1.94 for Avgas.

In my book that equates (approx) to £3.44 per gall (US) and £7.34. therefore the Jetprop cost approximatly £116 / hour in fuel as against £176 per hour for the Avgas. So a Jetprop fuel costs approximatly 35% less than the same airframe powered by an Avgas burning engine. If we factor in the expected TBO figures then your way ahead.

[peterh337]

Purchase cost?

I like the Jetprop too

[goldeneaglepilot]

I think the reality is that you get what you pay for, also what sells well tends to depreciate less in percentage terms.

You also seem to get few, if any issues of getting spare parts for a PA46.

With regards the argument about Turbine or diesel engines, it should be noted how may of the IO540 engined PA46's have had Jetprop conversions, its a logical upgrade on the PA46.

Bear in mind that a PA46 costs a fraction to operate of what a C421 did... Use for 300 hours per year and your talking of sensible savings on annual operating costs, even with the high capital outlay.

I think given time we will also see smaller versions of turbine proped engines.

[englishal]

Has anyone ever considered manufacturing PETROL (I.e regular 95 octane UL petrol) engines for aeroplanes based on car technology? For example a 4 cylinder, liquid cooled, Audi 200 HP car engine mated to a CS prop and using FADEC?

I would have thought the thing would be pretty light and pretty reliable (due to umpteen millions ploughed into development). I'd also have thought that power to weight would be higher than a diesel and that economy would be much improved over the Old Skool engines? I presume a petrol in this fashion would run at similar RPMs to a diesel and so could be made to work?

One other plus side is that PETROL is freely available worldwide, whether it be Ivory Coast or England or Alert. If you could achieve a 25% increase in economy, plus a 30% lower fuel price then that would keep a lot of people happy.

Would there be any point in even trying to develop a new petrol engine? What are the potential pitfalls?

[Hodja]

Where I see future potential is in small turbines.

As Peter said, very doubtful. R&D costs, certification costs, basic thermodynamics and a shrinking GA market makes this a long shot.

Also turbines are a totally different class of airplanes. You have to fly them like an airliner. For 150hr/year of recreational flying, they're a pipe dream.

Incidentally, all these speculative turbine-envy lifestyle discussions somehow always seems to end up at the JetPROP/Meridian, even though it's a noisy 70s design w/the range of a Cirrus...(cuz' it's the only turbine we could conceivably afford )

The AIR BP booklet shows avgas available in some suprising places

Ah, yes. Ever actually tried arranging for avgas in some of these surprising places? Either the booklet info turns to be out of date, the actual supply turns to be unavailable when you actually need it, or you need to preposition the drums a month in advance, at exorbitant costs.

Avgas *is* more or less available all around World. The problem is flexibility. You're simply excluded from a large number of airports which don't, and exposed to availability issues at those that do. Even in Europe you have to plan your routings carefully to account for availability.

Finally, I hate to bring up environmental concerns, but in this day & age fuel efficiency counts, and I don't see a bright future for 28gph twin piston avgas guzzlers... - btw, I really like the Tecnam P2006T concept w/Rotax mogas, but at 600nm range & 135 kts cruise, the specs are less than ideal.

(edit: Sure would be nice with a TBM though - I know we don't "need" it per se, but still... )

[Hodja]

Otherwise, car engines and car technology are not competitive with aircraft engine technology

Painfully true. The best we can hope for is an approximation, considering the apparent non-viability of developing clean sheet engine designs for light aircraft.

I wonder how differently the Austro engine design varies from its Mercedes automotive origin...(btw, I read Diamond paid EUR48m for the development & certification cost - yikes)

[achimha]

I wonder how differently the Austro engine design varies from its Mercedes automotive origin...

Funny enough, the Austro Engine AE300 is much closer to the Mercedes A class engine than the Thielert engine. Thielert make a lot of lightweight parts whereas Austro go for the original parts, e.g. the steel crankcase. The AE300 is therefore much heavier and also larger than the Thielert which they compensate for by having a higher BHP rating. Their upcoming 6 cylinder monobloc engine also looks scary (based on a tank engine)

IMO not much is wrong with the Thielert engine, their business case was just a tad too optimistic and they got into this useless fight with Diamond which resulted in the wasteful development of almost the same engine from scratch. Their model was absolutely great: you pay a fixed price per hour and whatever happens, Thielert would fix it. One could argue that Lycoming are still in business because they make customers pay to fix crappy products (remember the crankshaft AD?).

Both Thielert and Austro Engine are based on an outdated Mercedes engine (OM668, known as A 170 CDI). Thielert have always said this wouldn't be an issue because they manufacture most parts themselves and once Mercedes is out of supply, they would produce/source the remaining bits themselves. Given that their engine really is very different from the stock Mercedes, this always sounded more credible to me than the Austro story.

Car engines will always require a gearbox and that is a serious weak spot. Look at Thielert's 300h interval (is it 600h now? Update: according to their website it is 600h as of Dec 19, 2011). I don't think that's because Thielert engineers are incompetent.

Porsche had similar issues with their PFM3200. They had to call back all planes and replace the 2 blade McCauley props with expensive composite 3 blade MT props to reduce vibration which would kill the gearboxes. The PFM3200 is a good and reliable engine and we'd probably flying one today had Porsche stayed in that business.

One could argue that engines with gearboxes will never succeed but one could also argue against that. There are some geared Lycomings around (Cessna 421, old Aero Commander) and even the big turbine makers are working on geared turbofans.

Something like DeltaHawk/Gemini/Zoche would be ideal but it will be hard to get to a reliable and affordable product in such a small and conservative market. Let's hope the military will pour many millions in those projects.

I agree with Peter that small turbines are most likely not the future. A turbine gets much less thrust out of a liter of fuel than a piston engine and the smaller it is, the less efficient. Turbines are very well researched and no breakthrough discoveries to be expected.

[peterh337]

goldeneaglepilot - having flown in both a 421C and the Jetprop and having a little bit of knowledge of both (more of the latter) I would not be suprised if the Jetprop turned out to be cheaper in all respects, except the original capital cost which is about £100k-200k for a 421C versus about $1M for a Jetprop (both obviously used specimens). A brand new JP is about $1.5M. And the 421C will carry more stuff.

I also agree that a Jetprop is the only logical way forward from an IO540 engined plane - which is why I am sticking with what I've got The TB20 fits my mission profile.

But this comparison is at the very top end of piston GA, and works in favour of the JP due to the relatively huge avgas bills in the 421C.

Even a TBM700 costs less direct operating cost per mile than my TB20, but the purchase cost is $1.3M versus $200k for comparable specimens, or $3.2M versus $300k at new prices.

With such massive purchase price differences one cannot meaningfully talk about the operating cost being similar or whatever, because a million bucks buys you more avgas than most could burn in the rest of their life.

[Jan Olieslagers]

One could argue that engines with gearboxes will never succeed

Oh no, you couldn't. Or you'd have to convince me the Merlin, Jumo205-208, Wright Cyclone &c &dc did not succeed. And yes, all of these are big engines, yes, but there was the Pobjoy, too. Gearboxes have been around for decades, nothing new or difficult about them. They do work better at high rpm's and with lots of cylinders, though.

[Jan Olieslagers]

Has anyone ever considered manufacturing PETROL (I.e regular 95 octane UL petrol) engines for aeroplanes based on car technology?

Check "Eggenfellner" for just one example.

[abgd]

There've also been any number of conversions of Volkswagen and Mazda Wankel engines for use in homebuilts. The Volkswagens seem to be fairly well respected but are still not as reliable as dedicated aircraft engines.

[27/09]

Jan Olieslagers

Gearboxes have been around for decades, nothing new or difficult about them. They do work better at high rpm's and with lots of cylinders, though.

Generally gearboxes are only reliable with engines of more than 8 cylinders ,the Pobjoy woud be the exception I think, and perhaps due to the generally low horsepower they produced.

[Hodja]

Both Thielert and Austro Engine are based on an outdated Mercedes engine (OM668, known as A 170 CDI).

Just noticed, that the Thielert 2.0 & Austro is actually based on the successor OM640 Merc engine (found in the current model A200 CDI), introduced about 3-4 years after the OM668.

[Immortal]

Originally Posted by achimha

The Rotax powered fleet tend to use 98 octane mogas. Unfortunately the EU now requires the oil companies to add up to 10% ethanol which the Rotax engines/fuel systems are not certified for so aerodromes have to determine the ethanol concentration for each fuel delivery.

In fact the do run on E10. See the latest service instruction from Rotax: http://www.flyrotax.com/portaldata/5/dokus/d04899.pdf it's listed on page 10.

Interesting topic about diesel and aviation. Personally I believe in electric rather than diesel as a future for the GA. Some day the oil wells be be dry and according to some, this is going to happen sooner than later.

Electric engines just have so many advantages if compared to piston or diesel driven engines. No more oil changes or carburetor icing, no more leaning or having to worry about the availability of "juice" for the ride. No more oil checks before flight or having to suffer of a massive decrease in performance when we visit an altiport.

Sure we have a long way to go before we have batteries which are light enough to take up in the air and still providing enough power to get from the UK to the Costa Brava and some way to "fill the tanks" in a short period of time. But still the lookout for electric flying is promising.

In the meantime maybe Diesel, but it's mostly an European problem. Most of the GA of the world takes place in the US and as long as they will provide AVGAS, I don't see a mayor breakthrough in diesel technologies as long it's just a supply and demand problem.