Diamond DA42V1

[Hodja]

Some new developments over at Diamond...

Diamond Aircraft :: DA42 V1 crosses the 200 knots speed barrier (http://www.diamond-air.at/news_detail+M517c78b05f4.html)

> 200kts true, obviously under unrealistically ideal conditions.

But still - if the improved aerodynamics & prop alone brings an extra 5-10 kts in ordinary use, that's definitely a plus, and finally puts the DA42 Austro into serious running with parts of the competition.

Also nice to see Diamond investing resources on actively improving the aircraft fundamentals.

[peterh337]

They were talking about 210kt for the original DA42 as well.

Maybe somebody sneaked a pair of PT6s into the test aircraft :)

[A and C]

And I was thinking I had never seen a V1 speed of over 185 kts on a B737-800 at MTOW take off at Sharm on a hot day.

This DA42 must be a hot ship !!!!!?

[colby]

What's the fuel flow like on the Austro engines? Selling point on the TDI is fuel economy - wonder if that spills over to the V1?

[B2N2]

Did anybody consider the irony of the name? :ugh:

[soay]

http://www.diamond-air.at/uploads/tx_ricrotation/DA52_small.jpg

From Diamond Aircraft :: Home (http://www.diamond-air.at/)

[n5296s]

I suppose that's their little joke.

The DA42 is the one aircraft that could convince me to get a twin rating (well, practical aircraft - would be fun to get some DC3 time). If they finally have a viable powerplant and they've pushed the speed up a bit, then (for me anyway) this would be just about the perfect personal plane.

n5296s

[peterh337]

200kt TAS at FL180, ISA, is only about 147kt IAS.

The stock DA42 TDi will do that much at low levels so it's just a case of having enough turbo boost at FL180.

The usual plane salesmen's trick :)

I've been up to FL200 in the TB20 and can tell you that breathing at FL180+ is a full time job with a cannula. It's OK but you need to monitor passengers fairly carefully. Masks are fine but you get through an awful lot of gas.

I wonder what the ceiling is. That is really more important. If it does 147kt IAS at FL180 then it should go to at least FL250 and that is a really useful capability because you can outclimb most warm front weather, and you can outclimb most organised IMC in which nasties could be hiding.

Most turbocharged piston IFR tourers will do FL250 or so but almost none of them make TBO without changing some cylinders (or worse).

But then the Diamond engines are much less proven than that, so we have some way to go.

[n5296s]

200kt TAS at FL180, ISA, is only about 147kt IAS
Well, except that prop efficiency falls off with altitude. My plane will do 140 KIAS at sea level (well, a few feet above it works better) but at FL200 it's down to under 125. Maybe that's not true for all props/planes.

I agree that these kind of altitudes really require pressurization. I've done long flights at FL180 and above, a handful of times, and you spend a LOT of time checking the oximeter and the integrity of the plumbing! I very rarely go much above 10000' unless I need to for the terrain.

All I really want is something which doesn't actually go SLOWER than my TR182.

[peterh337]

Well, except that prop efficiency falls off with altitude. My plane will do 140 KIAS at sea level (well, a few feet above it works better) but at FL200 it's down to under 125.

Was your engine delivering the same HP at FL200? That would amaze me; no GA turbo installation delivers sea level MP at FL200. Most of them go to about FL150 or so, and drop off beyond that.

[n5296s]

Was your engine delivering the same HP at FL200?
Well, I think so. I was running at the same MP/RPM as at sea level. I normally cruise at 25"/2200 RPM (76% according to the book). My plane is only turbo normalized, the turbo can still provide 25" at FL200 which is the official ceiling, and still has some oomph left though I've never been higher than that. I'd guess you could keep 25" to about FL230.

[FlyingStone]

200kt TAS at FL180, ISA, is only about 147kt IAS.

The stock DA42 TDi will do that much at low levels so it's just a case of having enough turbo boost at FL180.

The usual plane salesmen's trick

But does IAS really matter in performance (except for people who've never been above 5000ft)? I always though TAS is the only important figure for cruise (besides the fuel flow to achieve it) and IAS is just a number full of errors (compressibility, position, instrument, ...). I'm ready to be proven wrong.

Was your engine delivering the same HP at FL200? That would amaze me; no GA turbo installation delivers sea level MP at FL200. Most of them go to about FL150 or so, and drop off beyond that.

Thielert Centurion 2.0 (obviously not applicable to AE300, but the numbers are likely very similar) produces around 2,25 bar of manifold pressure at 100% load which is cca. 65". Obviously almost twice as much as normal turbo installation, where 40" seems to be the normal MP for maximum power. Given that, I think the turbo should be able to maintain at least sea level MP at FL200 :)

[peterh337]

What is it? A Mustang? :E

[n5296s]

You mean one of these:

Mustang | Flickr - Photo Sharing! (http://www.flickr.com/photos/27441829@N06/2813264728/)

No, I'm afraid my ride is a TR182 - a Lycoming O540 with a turbocharger added by Cessna. The turbo can give over 20" of boost. The wastegate is manually controlled by the second half of the throttle control movement.

(I tried linking the picture directly using [IMG] tags but it didn't work).

[Fuji Abound]

The 42s ok but with a lot of hours in both the 42 and a cirrus i have to conclude the cirrus is better. Its faster, the cabin is more comfortable, the ride a lot better and the performance more sprightly. The best thing the 42 has going for it is how quiet and smooth the engines are compared with lycomings best.

Frankly for either to be better they would need to be pressurised or another 50 knots found otherwise it is all symantics.

[Hodja]

For a "World" cruiser, though, the Jet A feature is hard to beat, and makes this stand out compared to a Cirrus. Outside Europe, US & Aus/NZ, sourcing avgas can be a right pain.

And twin engines across open oceans does make this one a slightly better option travelling with non-pilot passengers. (at least in terms of passenger perception/acceptance)


Frankly for either to be better they would need to be pressurised or another 50 knots found otherwise it is all symantics.


Completely agree. An extra 20-30 kts on top of the original DA42 Thielert 1.7 is a very nice addition, but doesn't elevate the DA42 anywhere near the next class. (turbine, pressuration, wx radar...) It would merely bridge the embarrasing performance shortfall between the original DA42 and its targeted competition. I mean, who would want to buy a brand new twin that tops out at 155 ktas at FL110?!

I'd still say though, that if the (untested) Austro's can go the distance, the DA42 V1 really has the potential to hit the sweet spot as a very nice modern design personal twin piston tourer in the USD500-800k bracket.

Unfortunately the Thielert saga left an ocean of badwill, so it's an uphill battle at best.

But I'll still be keen to follow the performance data for the DA42 V1 when they're released in march 2012. If it delivers an honest 185 ktas at FL110 using 12-13 gph of Jet A (or, say ~200 ktas at FL160) and the Austros can go the distance, this bird would definitely be on my list...


Most turbocharged piston IFR tourers will do FL250 or so but almost none of them make TBO without changing some cylinders (or worse).



I've seen the Corvalis 400 doing FL250. However, I wonder how many owners actually fly at this level in real life. I personally feel unpressurised pistons really aren't the proper platform for this kind of flight profile...

[soay]

The cockpit of the DA52, pictured above, looks strong enough to be pressurised. The view out can't be as good as from a DA42 though. I wonder if it is a 5 seater, like the DA50.

[silverknapper]

and the Austros can go the distance, this bird would definitely be on my list...

Sadly this is the problem. How long do you wait to achieve this criteria. 2 years? 5 years? If I were parting with my hard earned I'd need a lot of convincing. There will be inevitable teething problems, but I think I'd need to see a sample of 100 airframes make TBO before I'd even consider it. I'm sure the folks who took a punt on the original disaster would think I'm being cautious!

When Continental release their diesel motor I would start to get interested but until then personally I'd be too scared.

[peterh337]

I think that is a reasonable attitude if spending your own money.

It is now clear that Diamond will not rush to tell people of engine problems because they need to sell airframes and they cannot shift them without the motors :)

If problems surface after delivery, that is OK because they have got paid and the issue shifts into the normal warranty process where it can be, shall we say, "managed"........ hey ho this is aviation after all :E

At the height of the Thielert debacle they had, according to a friend who visited their factory, some vast number (many dozens, IIRC) of DA42 airframes which could not be delivered because there were no engines. Obviously, Diamond tried everything to stop people cancelling orders. In one case where I know the chap very well, Mr Dries personally offered the customer a D-Jet at a discount price :) That would have been an absolute scream. There is absolutely not one single person I have ever spoken to privately who has had direct dealings with the factory and who speaks well of the way they do business.

Also, Diamond has recently been sold to some Middle East outfit which has no apparent aviation experience.

[Pilot DAR]

The DA42 with Thielert engines was a delight to fly - smooth and simple to operate. The engine longevity seemed to be a problem. Ultimately their availability became a crisis.

The DA 42-360L was an improvement in many ways, engine history and reliability being chief among them. The compromise became economy, and a return to "old tech". The dependance upon 100LL another undesirable aspect. 180 HP a side sure makes for a great performer though! We did have one up to 19,200 feet during testing, but did not stay long enough to gather any cruise performance data.

I have great hopes for the success of the new diesel engines, but know nothing about them. Like any new powerplant, there comes the inevitable question as to how long you should wait/how many in service, before you buy in. It's a personal decision...

I also have great hopes for the SMA diesel, as we have an order in for one. Things are delayed, but my hope remains. Though I believe that Continental will market a good diesel engine too, I believe that SMA will remain well ahead of Continental for some time to come.

The future is diesel though....

[A and C]

There is a lot of half truth floating about when it comes to the diesel engines avalble for the DA42.
Both the engines are based on Merc car engines with Thielert favoring the alloy crackcase and Austro going for the steel, the Thielert is lighter but the Austro produces more power, in realistic terms the performance delivered to the aircraft is much the same. Austro have been very conservative with the rated power and I am told that in the test cell the Austro has run as for a long time at power settings of up to 200bhp.

The Austro has the advantage of using the experience of Thielert in the development, the biggest problem that was encountered with the Thielert was corrosion in the cylinder heads, Thielert had no problems with this in the aircraft that they retrofitted or with the Robin instalation that they had total control over. The corrosion was found to be an electrolytic reaction between the cylinder head and the heat exchangers with the coolant forming the electrolyte. Who wrote the spec for the heat exchangers is unclear but following the problem Astro have been very carefull to mandate the approved coolant.

Thielert now have a lot of running time on the engines in UAV's and the engine is starting to mature, I am not sure what other products the Austro is used in but I would think that Austro will have a long way to go to match Thielerts flight time.

The Austro was an engine born out of the difficultys between the two company's and it is interesting to see how two engines based on a very similar car engine have evolved, I do however feel that Austro have taken advantage of a lot of hard won development at Thielert.

[421C]

200kt TAS at FL180, ISA, is only about 147kt IAS.

The stock DA42 TDi will do that much at low levels so it's just a case of having enough turbo boost at FL180.
With constant power, IAS declines with increasing density altitude. TAS does increase since drag decreases, but to keep IAS constant would take more power, since IAS is proportional to the drag and power = force x distance / time, ie. at a given IAS it takes a certain energy to cover 1nm through the air. At higher level and higher TAS, that happens in less time, so energy expended per unit time (power) must be higher. IIRC, prop efficiency is a minor effect. As a very rough example, in the 421 at 60% power, IAS is 165 at SL and 140 at 20k' but TAS is 200kts.
Many turbo piston engines maintain SL boost well above 15k, to >20k

[peterh337]

With constant power, IAS declines with increasing density altitude

In that case, how come my TB20 does exactly the same IAS of 138kt at constant engine power, say 23" / 2400rpm / 11.3GPH (peak EGT, maybe slightly LOP) at all altitudes below which 23" can be obtained.

[421C]

I don't know. The effect of declining IAS is small at lower levels and there may be other effects outweighing that, of prop efficiency etc and power not being exactly constant with constant MP/RPM/FF at increasing altitude. The TB20 may do many things, but defying the laws of physics isn't one of them!

[peterh337]

to keep IAS constant would take more power, since IAS is proportional to the drag and power = force x distance / time, ie. at a given IAS it takes a certain energy to cover 1nm through the air

How sure are you about that, 421C?

[goldeneaglepilot]

I totally agree that the future is diesel, either in the form of turbo prop or diesel engine.

It would be interesting to see how the DA42TDI (2.0L engines) compare in terms of economy against, lets say a TB20? For arguments sake lets say at FL100 at 60% and 80% power.

Perhaps someone could do a direct price comparison based on AVGAS price v JET A1 using UK prices per litre? For ease of calculation lets say a direct flight of 500nm, the interesting figures would be estimated time of flight, cruise speed, total fuel cost for the flight and total fuel burnt in litres.

Peter - your thoughts on this?

A and C - your correct about the respect the UAV industry has for Thielart engines, the use of Thielart engines in the Grey Eagle and earlier Warrior UAV's has shown extreme performance, good reliabilty and most importantly the ability to withstand harsh operating regimes. It also operates on a fuel with a much wider spec tolerance than Jet A1 without adverse affect on power and reliability

[peterh337]

I don't think a DA42 diesel v. TB20 comparison is very useful because the diesel has a huge advantage in fuel availability in Europe and even more so in the 3rd world.

But, FWIW, I have flown in the original DA42 TDi and it was doing 140kt at a combined fuel flow of ~ 11 USG/hr which is almost exactly what my TB20 does. This makes sense since the two have similar volume cockpits, the DA42 has the extra drag of the 2nd engine, but is more streamlined, has a higher engine compression ratio, and there is no free lunch :)

At FL100, the TB20 does 140kt TAS on about 9.5 USG/hr, at peak EGT, 2200rpm.

The UK diesel v avgas price comparison is difficult too because they have just stuck a tax on diesel for "leisure" use, which you are supposed to self declare. However "training" is exempted, AIUI, so I guess everybody is doing a lot of training flights now. I really have no idea how this is supposed to work, and I don't know avtur pricing around Europe. Certainly the avtur tax in private use kills the diesel engine market for private-aircraft retrofits, totally.

[goldeneaglepilot]

Interesting comparisons Peter, The DA42 TDI does a little under 9 galls per hour (total) at about 150kts at FL100. Even with the UK tax rules it still works out at approximatly 65% of the fuel cost of Avgas, so a saving per mile of around 35%. Even more saving if its a training flight.

There is of course the added safety advantadge of a proper deice system, two engines and a significant improvement in instrumentation / autopilot system.

The other advantadge is a composite construction with modern aerodynamics and wing section, less parasitic drag, higher aerodynamic efficency etc..

Whilst the TB20 is a great aeroplane, natural evolution has seen its design superseded.

Will they do a diesel version equivalent of the IO540?

[Pilot DAR]

Will they do a diesel version equivalent of the IO540?

Yes. They (SMA) have built and approved the SR305-230E diesel, which is very promising. I have one ordered for a client's C 182 amphibian. It's the way of the future. The power is 230 HP, more powerful versions will come in the future.

[silverknapper]

natural evolution has seen its design superseded.

If natural evolution means having an aircraft with engines that don't work, a finished product which delivers 20% less speed than I was told when I placed a deposit and a residual value that makes a brand new Vauxhall seem a good buy you can honestly keep it. As for training, ask around and you'll find very few schools sing their praises due to unservicabilities.

Not sure I'd call TKS a proper de ice system to be honest. Certainly better than nothing though.

I have no doubt diesel is the future, it's a certainty. But if I were gambling my hard earned right now I wouldn't touch it. And that's exactly what it is. A gamble. Diamond didn't look after their customers last time round. Why would they if the Austro went wrong.

[englishal]

In my experience a 2.0L DA42 will give a 165Kt TAS cruise at 12 USG (6 per side) per hour at 10,000' at 75% power. When the original DA42 did a flight from Newfoundland to Porto in Portugal it used $200 of Jet A and took 12 hrs non stop. No need for ferry tanks either if you get the extended range tanks.

I have heard various things about Diamond quality and customer service, but I presume this is a European thing as it seems quite different in the USA?

[englishal]

However...if you want to take your light aeroplane on a long distance trip, then burning Jet is undoubtedly better. I know of someone who took their DA42 from the USA to South America and did a tour down there before flying home....something next to impossible with Avgas. For us in Euroland, the same applies....

I am sure the same was said about Diesel cars in the past, and if you look at the USA ,in California you can't even buy a Diesel VW which does 60 MPG , yet you can buy a crappy new petrol Mustang which does 20 at a push (and has a 3 speed gearbox). Every second car in Europe is a diesel, it is efficient, and is the norm (and arguably better), and the technical advances are light years ahead of the old skool US cars with diesel engines running half a million miles without batting an eyelid.

But I agree, if you fly where Avgas is available and priced correctly then there is not much incentive at the moment. I do think it is time for these gas powered Lycomings to be controlled by FADEC though which would improve efficiency and also engine life and make them easier to fly.

Trouble is someone has to be first to buy this new tech....I would if I could afford to, but I can't.

[peterh337]

Diamond didn't look after their customers last time round. Why would they if the Austro went wrong.

AIUI, Diamond were able to walk away from a % of the Thielert engine liability because the original aircraft were sold with separate warranties for the airframe and the engine. Under EU law this is unenforceable (it is IMHO obviously illegal to do such a stunt) on a private user, but many were sold to schools and they had no recourse against Diamond for engine issues. This is what one FTO owner told me.

This time round, if they get any trouble, Diamond won't be able to do that. What that means, one cannot tell. If there is a small amount of trouble they will have to deal with it. If there is a lot of trouble, they won't be able to afford to deal with it and will do all they can to wash their hands of it.

I don't know any Diamond owner who would trust the company (in Europe) as far as he can throw them, so the issue is really a bet on the reliability of the product.

OTOH, I bet Diamond looked after their American customers a lot better. They have to.... trash your reputation in the USA and it is game over, for ever.

Will they do a diesel version equivalent of the IO540?

I recall SMA (now owned by Continental) were doing an IO540- engine mounting compatible diesel. Oddly enough Socata do have a TB20 flying with it, and have had it for about 10 years, but the project was abandoned, reportedly due to severe vibration issues.

[goldeneaglepilot]

Silvaire - I do think the way forward is diesel or turbine. The high cost of Avgas is enough motivation to see that happen.

With regards your statement about Thielart powered UAV's being dogs, please explain why and on what basis you pass that opinion. Grey Warrior was a development of Warrior and later deployments of similar type were regarded as good. The main issue was finding an engine that could cope with a very wide specification fuel in theatre operations

[Pilot DAR]

SMA (now owned by Continental)

I think that SNCEMA would vigorously disagree with this.....

[goldeneaglepilot]

I think Peter made one of his famous typo's and intended to say "Continental are rumoured to have bought a licence to use SMA technology"

SMA (http://www.smaengines.com/spip.php?rubrique6&lang=en)

AOPA Online: Continental to offer Jet A engine (http://www.aopa.org/aircraft/articles/2010/100512continental.html)

http://www.smaengines.com/IMG/pdf/fiche_SMA_ang.pdf

I also see that SMA are currently flying a TB20 with one of their latest engines in it, as are two other companies with their own engines, all of this is news published in the last 18 months. No hint of giving up with a diesel TB20 due to vibration has said by Peter

[peterh337]

It was Socata who gave up on it a while ago.

However there is nobody left in Tarbes who has any interest in anything other than TBM sales.

If somebody else has since picked it up, that's good news :ok:

[A and C]

Any one know what has happened to the deltahawk engine ? the advantages listed on the website would even have Slivaire1 chopping in his avgas burners for a diesel !

[27/09]

I am sure the same was said about Diesel cars in the past, and if you look at the USA ,in California you can't even buy a Diesel VW which does 60 MPG , yet you can buy a crappy new petrol Mustang which does 20 at a push (and has a 3 speed gearbox). Every second car in Europe is a diesel, it is efficient, and is the norm (and arguably better), and the technical advances are light years ahead of the old skool US cars with diesel engines running half a million miles without batting an eyelid.

I agree but the problem is the aviation market isn't big enough to spread the development costs of new engines and make a product that everyone can afford. Lycoming and Continental had the luxury of living through the hey days of GA aircraft production in order to develop and refine their Avgas engines. Those days have gone, there were more aircraft sold in a few weeks then than there is in a whole year now.

I agree the diesel is where we should be heading however unless there is development that can be plucked plucked from a mass market (probably automobile) without any or much further development I don't see much new in the future for GA aircraft engines. Remember also where the biggest market is for GA aircraft, and that market right now or in the foreseeable future doesn't have much of a demand for diesel aircraft engines.

Another example, the flash new EFIS screens with their AHRS that we are now seeing in GA aircraft, like the Garmin, Avidyne, Aspen etc owe their heritage to the stability systems used in the modern car. If is wasn't for the mass production in the automobile industry to spread the development costs over we wouldn't seeing these nice glass GA cockpits.

[peterh337]

There are two things driving diesels in Europe:

1) Tax concessions (and these can do do disappear, and don't exist in the USA)

2) Reliance on avgas (which is not an issue for those suitably based who don't fly far, and is not an issue in the USA)

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

Diesels do have a bit better SFC, due to their higher compression ratio, but this brings technological problems with the severe torque pulses going into the prop. I am sure this will be solved eventually, but the jury is going to be out on long term diesel reliability for a long time.

I agree but the problem is the aviation market isn't big enough to spread the development costs of new engines and make a product that everyone can afford. Lycoming and Continental had the luxury of living through the hey days of GA aircraft production in order to develop and refine their Avgas engines. Those days have gone, there were more aircraft sold in a few weeks then than there is in a whole year now.

I think that is very well put, but 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.

[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]

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

[27/09]

peterh337I 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.

achimhaI 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.

achimhaI 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 OlieslagersGearboxes 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]

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.

[Shorrick Mk2]

Wonder why Continental have shelved their GAP diesel... was probably too reliable and would've put a dent into all the refurb' business driven by the "long reliable aviation engines of the '50es" *snicker*... interestingly enough my 250HP "notoriously unreliable auto engine" is now pushing 200k km with nothing but oil changes every 10k km.

[Hodja]

Some AVWeb commentary on the DA42 V1...

Diamond's New Twin (http://www.avweb.com/blogs/insider/AVWebInsider_DiamondNewTwin_206313-1.html)

Thought this comment was quite interesting...

I saw something at Austro that truly astonished me. On the floor of the factory were about 25 fully dressed OM-640 Mercedes engines, used in the A and B class. They were fresh from the factory. Daimler makes about 1500 of these engines * a day.* So I was looking at 20 minutes worth of production.

Austro uses the core of this engine for the AE300, stripping off the automotive components and building it back up with its own approved components. Those brand new fuel pumps, turbos and airboxes were off to the scrap heap. (Sigh.)

If you know anything about series production, you know the more of anything you build with less variability, the higher the potential QC level. So those cores are at automotive standards, not lesser aviation standards. That bodes well for long-term durability. The first Austros are just now coming in for overhaul, so they're beginning to see if the claims will potentiate.

posted by Paul Bertorelli on March 15, 2012

[soay]

More from AVWeb (http://www.avweb.com/avwebflash/news/DiamondsDries_FlyByWireAsElectronicParachute_206315-1.html):

"Diamond Aircraft says it's very close to flying a fly-by-wire version of its Austro-diesel-powered DA42 twin. ... This technology, says Dries, will be incorporated into the autopilot and he believes it will eventually evolve to include both flight envelope protection and full autoland capability for the DA42."

So, a V1 that can fly without a pilot. Didn't they make something like that in Wiener Neustadt in the 1940's?

[popobowa]

TYhe Austr Engine derives from the 3.0l MONOBLOCK Steyr engine (used in marine and other specailist )applications. It seems to be a superior design to THielert , stroger block/head, better thermal efficiency and has the "Pumpe-Duese" INjection system which is more tolerant to abuse and contaminated fuels as well that it has a mechanical "get home setting (in case of electronics failure) of 50-60%..at least the marine versions do....I would bet my $ on thire design to be the less costly to operate..pending gearbox times/

[popobowa]

Sorry got that wrong...I heard that block was meant for the larger engine...250-300hp