[woxofswa]

I've heard from a couple of sources that the Lycoming reps at Oshkosh were telling peeps that they will have a 540 sized diesel on the market within a year. That would be my perfect pulse for my expected RV10 project. Anyone have any updates or details? How many would there have to be for Van's to produce a finishing/FWF kit for that application?

 

[rv6ejguy]

Has Lycoming announced any price target for the engine yet? How about hp and weight?

 

[groucho]

Drool. I'm buying one. I'm not sure what I'll hang it on, but I need one. General aviation needs new powerplants. I hope this is the one that'll change everything.

 

[David-aviator]

Drool. I'm buying one. I'm not sure what I'll hang it on, but I need one. General aviation needs new powerplants. I hope this is the one that'll change everything.

I don't see how it will change anything....diesel comes out of the same hole as av gas. Lately, its price around here has been higher than regular gas, although it is lower than av gas - but not by much.

The reason these engines have not made it to market is all about economics. The cost of recertifying airplanes is prohibitive. Now if the plug were pulled on av gas, that would make a difference.

Maybe Lycoming knows something we don't.

 

[groucho]

I don't see how it will change anything....diesel comes out of the same hole as av gas.

Obviuosly, this whole thing is just pie in the sky for now & I can't make any hard & fast "it's gonna rule the world" comments. There are certainly some drawbacks & as we all know, just because a company talks about releasing something doesn't mean they will.

Jet A isn't available everywhere. So with the current spread of gas pumps, going diesel means you have a more limited set of refueling destinations. There are still lots of FBOs that do sell JetA. At least in my neck of the woods, most airports I fly to sell 100LL & JetA.

All that said, many huge leaps in aviation history have happened because of changes in propulsion. IMHO, military, commercial & general aviation all need new powerplants. Military: I still haven't met a fighter that has enough power. Commercial: improvements of only a couple percent can be the difference between making a profit or not. We're of course not here to solve military or commercial aviation issues. A relatively small improvement in GA engines can significantly change the capabilities of our planes. Tried the difference between a Blended Airfoil & "old" Hartzell prop? ...just an example of what a small change can do.

I'm sure there are several people here that have FADECs, lots that have fuel injection & even more that have electronic ignition. I'd hazard a guess that those who've upgraded their plane to one of these after flying with a bone stock 320 or 360 would have comments ranging from "I can tell" to "wow." Our engines ("our" = those with 320's, 360's & similar) were designed a very long time ago. The cost prohibitive nature of developing & certifying new engines is certainly one driving factor in development. As best I can tell, the O-360 was introduced in 1955. 1955!!! I'd bet that my engine is almost identical to that 1955 model. I guarantee the technology exists to make a better engine today.

A new engine doesn't have to be diesel. There are quite a few companies that are at least talking about their new diesel engines though. A few are:
http://www.zoche.de/
http://www.centurion-engines.com/
http://www.deltahawkengines.com/
Many have followed the progress of these & more...some companies actually have customers with flying engines & others haven't made much ground in years. While designing a new engine is far from trivial, I imagine that a new (i.e. from scratch) Lycoming diesel would be a very tempting powerplant for much of general aviation.

Honda has openly talked about their gas-powered aircraft engine development for several years. I heard a rumor Toyota is also developing a GA engine. Honda recently announced it is building a plant to build it's new jet engine in North Carolina. I haven't heard any news about their piston engine production though. I'd guess that a Honda or Toyota entry into the GA engine market would drastically change the landscape.

In all of this babble, all I'm really saying is that I want an easier to use, more reliable, higher powered, more efficient engine for our airplanes (well, at least my airplane ).

If nothing else, it's fun to talk about.

 

[KPmarc]

Lycoming said in 2006 that it would have a "heavy fuel" engine on display the next year. 2007 came and went without a peep.

Don't hold your breath.

I will say, however, that we're approaching the economic tipping point for diesels/Jet-A burners in the U.S. Cessna apparently agrees. Until the recent cost hikes on avgas, they didn't make much fiscal sense; now they are starting to.

Don't underestimate the task, either. Go look at the Thielert or SMA installations on certified airplanes. They're complex as all get out, and have vibration signatures that make the prop guys lose sleep. (In fact, I strongly suspect that Hartzell's investment in new composite technologies was based on an expectation that heavy-fuel engines would become more common.) Look at the sophisticated engine mounts on the four-cylinder Thielert...

Hanging one of these on the firewall of an RV-10 is going to make putting a rotary or a fuel cell engine seem like popping new AAs into your Maglite.

 

[sierradelta]

Dreaming

My perfect power plant choice would be a diesel....imagine converting it to biodeisel and running SVO.

Goodness then I could power my SVO Ford truck my SVO Agriculture Tractor and my SVO plane on the same fuel....That is a dream because I can produce my own fuel at home.

Oh technology can you please hurry up and make my dream come true!

 

[SvingenB]

I don't see how it will change anything....diesel comes out of the same hole as av gas. Lately, its price around here has been higher than regular gas, although it is lower than av gas - but not by much.

The reason these engines have not made it to market is all about economics. The cost of recertifying airplanes is prohibitive. Now if the plug were pulled on av gas, that would make a difference.

Maybe Lycoming knows something we don't.

A diesel engine will run on both jet fuel and diesel. Both these fuels, or at least one of them, can be found everywhere, even at the most remote places on the planet. Avgas is an exotic mix that only GA use, and much more highly refined than mogas. An airplane burning avgas needs a seperate infrastructure for storage and transport, while an airplane burning diesel don't, it can use existing autodiesel or jet insfrastructure. What I find strange is why avgas is so cheap in the US, and diesel/jet is expensive. Diesel is much less expensive to make, transport and store than either avgas or mogas.

I just hope someone will make an an ordinary air cooled turbo-diesel without all the expensive and unreliable gears, clutches, Common Rails, FADECs etc.

 

[rv6ejguy]

Where I fly mostly, neither jet nor diesel fuel is available at the airport so this would need to be addressed either by tankering, choosing routes based on fuel availability or installing diesel/ jet tanks at these smaller airports. I don't see the latter happening until many of thousands of diesel engines are being used in aircraft. At the present rate of diesel engine introduction and the current costs, this won't be for some time.

Diesels have a long ways to go IMO before they become a reasonable choice for weekend fliers like most of us on this forum are.

Bumming a ride into town with a few jerry cans to get diesel is ridiculous.

For flight schools and those making long trips to major centers, diesels make more sense if reliability gets up there with Lycoming engines. Thielert engines have not shown that to be true in service unfortunately.

 

[airguy]

You'll begin to see large(r) numbers of homebuilders with 75-gallon built-in fuel tanks in the bed of a pickup, an extremely common sight in West Texas and other farming communities where it's often very handy to have a mobile diesel pump, even if it's of limited capacity. I honestly cannot count the numbers of people I know that have a 75 or 100 gallon diesel tank with electric pumps in the back of a gasoline-fueled pickup. Between that and extended-range fuel tanks to tanker fuel for shorter round trips, much of your fuel availability problems would be resolved.

I, too, believe that the efficiency of a water-cooled turbodiesel is going to become more and more attractive (and thus see more usage) for small aircraft within the next 10-20 years, eventually becoming commonplace.

The reason these engines have not made it to market is all about economics. The cost of recertifying airplanes is prohibitive. Now if the plug were pulled on av gas, that would make a difference.

Exactly true - but we don't have to certify the engine - nor the airplane - we just have to make it work to our satisfaction. The market will follow any lead proven to be viable.

I just hope someone will make an an ordinary air cooled turbo-diesel without all the expensive and unreliable gears, clutches, Common Rails, FADECs etc.

Not likely with air cooling - it's been tried before and is just not practical. Air cooling means the thermal variation between ambient temperature and running engine is quite large - meaning you have a large amount of thermal expansion to deal with, which requires loose tolerances to allow the engine to operate without physically seizing itself up during operation. Loose tolerances encourage high oil usage (quart every 4-6 hours, anyone??) and make it more difficult to seal the piston within the cylinder properly for high compression, which is an absolute necessity for a diesel. Additionally, air cooling limits the rate at which heat can be rejected to atmosphere (temperature differential and surface area), which can severely impact the amount of power that can be extracted from a small engine without overtemping the cylinders. It's simple mathematics that allows us to extract more power from a given displacement with water cooling versus air cooling. You'll have a larger radiator (and associated cooling drag) to deal with, but you can get a much high power output for a given engine size and weight. At some point it becomes advantageous to pay the weight and drag penalty and use water cooling. Is that point within our useful aircraft engineering envelope for 2- and 4-place aircraft? Dunno - but I'm betting we find out within the next 10 years.

 

[Dave_Boxall]

Continental diesel

I think this makes it likely that Continental are planning a diesel.


http://http://www.flyer.co.uk/news/nib.php?artnum=565

Diesel guru joins Continental


After a split with the UK company that continues to develop the WAM-120 diesel aero engine and a brief sojourn in his native Australia, designer Mark Wilksch has reappeared on the general aviation scene with his appointment as director of new engine development at Teledyne Continental Motors (TCM).

Although it is associated with 'traditional' aero engines, TCM was working on its own aircraft diesel engine some years ago. It's easy to speculate that Wilksch, whose WAM-120 was very much a 'clean sheet of paper' design, may have been brought in to set some kind of diesel programme back in motion at the US giant, which is based in Mobile, Alabama.

Dave

 

[the_other_dougreeves]

The timeline of any engine development project is subject to change, but the concept makes sense. Here's why:
* The days of leaded AvGas are numbered
* Going with a single aviation fuel - Jet-A - would simplify the logistics chain for FBOs (look what JP-8 has done for the military)
* Diesel and Jet-A can be made into biofuels just as simply as gasoline
* Diesel is safer to handle than AvGas

If it can be made to work, diesel-cycle engines burning Jet-A make a lot of sense for GA. The problem, of course, it making it work. Putting the resources of TCM and/or Lyc behind the problem could make a difference. Of course, people said that about GM and diesel cars in the 80s ....

TODR

 

[SvingenB]

Not likely with air cooling - it's been tried before and is just not practical. Air cooling means the thermal variation between ambient temperature and running engine is quite large - meaning you have a large amount of thermal expansion to deal with, which requires loose tolerances to allow the engine to operate without physically seizing itself up during operation. Loose tolerances encourage high oil usage (quart every 4-6 hours, anyone??) and make it more difficult to seal the piston within the cylinder properly for high compression, which is an absolute necessity for a diesel. Additionally, air cooling limits the rate at which heat can be rejected to atmosphere (temperature differential and surface area), which can severely impact the amount of power that can be extracted from a small engine without overtemping the cylinders. It's simple mathematics that allows us to extract more power from a given displacement with water cooling versus air cooling. You'll have a larger radiator (and associated cooling drag) to deal with, but you can get a much high power output for a given engine size and weight. At some point it becomes advantageous to pay the weight and drag penalty and use water cooling. Is that point within our useful aircraft engineering envelope for 2- and 4-place aircraft? Dunno - but I'm betting we find out within the next 10 years.

You are probably right. On the other hand, the rumours about Thielert is that is a good engine - when it works. The problem is that it spends more time in the repair shop than in the air. The engine is not the problem, it is everything around it (FADEC, gear etc). Just because it is possible to do it, and it can even have lots of benefits (FADEC for instance), doesn't mean it is the right thing to do. It is more important not to worry about poor reliability than not to worry about an extra lever or two.

The WAM 160 looks like it could fit into a -4. Are they still alive?

 

[rv6ejguy]

You are probably right. On the other hand, the rumours about Thielert is that is a good engine - when it works. The problem is that it spends more time in the repair shop than in the air. The engine is not the problem, it is everything around it (FADEC, gear etc). Just because it is possible to do it, and it can even have lots of benefits (FADEC for instance), doesn't mean it is the right thing to do. It is more important not to worry about poor reliability than not to worry about an extra lever or two.

The WAM 160 looks like it could fit into a -4. Are they still alive?

I'd disagree. The Thielert is having serious mechanical wear issues especially in the piston/ring areas resulting in extreme oil consumption and blowby in the 500-1000 hour range. The FADECs are actually pretty reliable. The electrical system on the TwinStar was not well thought out but the recent accident in Europe would never hve happened had the pilots followed the published operating procedures. The reduction gear clutching system has caused most of the immediate power loss issues to date with at least one other coolant loss problem I'm aware of.

At this time, the Thielert engines are not realizing the dream of reliable, low maintenance diesel aircraft powerplants. Fortunately Thielert is addressing all known field problems with new mods and engines quite quickly. Kudos to them for this at least. In my view, many of the mechanical issues these engines are experiencing could have been uncovered before introduction with a more in depth WOT testing program. Flogging an engine design at max power until something happens works wonders. With abbreviated testing programs, I've seen this issue before with the introduction of many race engine designs in IMSA, IRL and IndyCar with embarrassing results for the manufacturers. Flog it, flog it, flog it until nothing breaks on 10 different engines for the design life- then release it for production. This is way cheaper than replacing units in the field and retooling production lines.

While this does not uncover every problem, it does reduce problems in service.

 

[Harvey L. Sorensen]

A couple of years ago at Oshkosh Lycoming had on desplay in their tent a flat diesel engine that they were working on. I dont remember if it was air or liqued cooled. I couldn't find anyone that would talk much about it.

 

[rv6ejguy]

Until Lycoming, Continental or Thielert gets something really good designed and priced competitive with current gasoline engines, I don't see a big market. To really catch on, one of these guys with their dealer network and reputation will have to be involved.

Companies like SMA http://www.smaengines.com/spip.php?id_rubrique=2&id_article=8&page=home
Have been fooling around for a decade with little to show for all the work. Apparently recent financial woes are over and they are moving forward again. The stillborn Cirrus TDI concept has been pretty much dormant since announced in 2001.

Making a diesel reliable and long lived for aviation is a big task IMO. I like the big, direct drive SMA idea compared to the Thielert's geared approach with tiny engines. Making a redrive live with a diesel and keeping it lightweight is even harder as Thielert has learned the hard way.

 

[penguin]

Lycoming have partnered with a British company called Cosworth, who has made Formula 1, CART and other motor sport engines for many years. Few details are available but I understand there should be some tangible results for their collaboration within the next few years - including detail improvements to current engines as well as new products. Perhaps the diesel is an example?

Pete

 

[rv6ejguy]

Lycoming have partnered with a British company called Cosworth, who has made Formula 1, CART and other motor sport engines for many years. Few details are available but I understand there should be some tangible results for their collaboration within the next few years - including detail improvements to current engines as well as new products. Perhaps the diesel is an example?

Pete

Cosworth has designed some great engines over the years, this can only be good news. Both companies are on the learning curve with diesels however. Will be interesting to see what they come up with.

 

[jdmunzell]

Fuel economy???

I know very little about diesels, but isn't one of the big benefits of diesel engines their fuel economy? Seems I read somewhere that pound for pound, they burn about half of what standard 100LL engines burn.

Can anybody substantiate that?

 

[airguy]

Not half, but about 80% to 85% would be fair, I believe. They are more fuel-efficient (especially when heavily turbocharged) because they are inherently running lean-of-peak during all operating phases. You have no pressure losses to speak of in the induction side (no throttle plate, only filter and ducts), and you simply inject enough fuel into the cylinder to create the desired amount of power, up to the limit of the available oxygen in the cylinder.

No offense to Ross, but redrives worry me a good deal. Subie guys seem to be on to something lately with them, and they are learning fast with a lot to show to their credit, but it still nags at my noggin. I like the Deltahawk design of 2-cycle direct-drive turbocharged - you still get the high power output with a light engine (requiring water cooling) but you don't need a redrive, and you get full power to about 18k'. From a physics and thermodynamics point of view, this is the ideal drive for a constant-speed prop. Downsides are vibration characteristics which the prop has to account for - only time and testing will tell the story on that.

 

[woxofswa]

Years ago, Sport Aviation wrote about a "Rotary Vee" engine. The physics made a lot of sense to this neophyte. I know Bricklin was playing around with the same concept for automobiles before running out of money. I wonder how many great ideas are just proper funding away from fruition. Wasn't the NASA project supposed to spur some new technology? I guess if new wildcat ideas don't interest a Rutan or a Branson, they don't get off the ground.
https://engineering.purdue.edu/people/christopher.n.deckard.1/Projects/Rotary/RotaryVee

 

[rv6ejguy]

I know very little about diesels, but isn't one of the big benefits of diesel engines their fuel economy? Seems I read somewhere that pound for pound, they burn about half of what standard 100LL engines burn.

Can anybody substantiate that?

Actually, to date, the flying diesels are only marginally better in the SFC department over a well set up injected Lycoming running LOP. The Thielert 1.7 is around .35, some good Lycos and Contis are around .38. When you figure in the initial cost, lower TBO/ TBR and higher weight, the economics just aren't there in the real world yet, despite what many diesel advocates would like to think. Maybe in the future with improved designs.

The 2 stroke diesel may fare better with no problematical valves and higher power to weight ratios but these are virtually unproven in aviation so far. I still worry about piston and ring problems on these designs.

100LL may disappear in a few more years or decades to be replaced with unleaded avgas but tens of thousands of existing aircraft won't be scrapped overnight or fitted with diesels. Let's be realistic here.

 

[Ron Lee]

Amen Ross

And the notion that FADEC is some magic elixir is nonsense. I saw one aircraft that had it installed and it convinced me that it is not worth it. The plane was destroyed in an off-field landing (not many months after first flight) when there was some sort of powerplant/ignition/FADEC issue.

 

[rv6ejguy]

I understand there have been a few ECUs replaced on the Thielerts but the Twin Star crash was not an ECU failure per se, rather a charging system/ low voltage fault caused by stupid pilots disregarding the manual. The engineers writing the manual correctly identified the possibility of this happening but the pilots ignored the warnings. I do think a better electrical system could be designed for this aircraft.

The fact remains, FADECS need power and common rail direct injection needs FADECs. Perhaps aviation is not ready for this technology. Maybe an old Bosch injection pump with old type mechanical nozzles is what should be fitted to new aviation diesels. Mechanics can understand and fix this stuff and no power is required to keep it running. Pretty reliable stuff with good fuel and water filtration at the expense of a bit of fuel economy.

 

[airguy]

Actually, to date, the flying diesels are only marginally better in the SFC department over a well set up injected Lycoming running LOP. The Thielert 1.7 is around .35, some good Lycos and Contis are around .38. When you figure in the initial cost, lower TBO/ TBR and higher weight, the economics just aren't there in the real world yet, despite what many diesel advocates would like to think. Maybe in the future with improved designs.

The 2 stroke diesel may fare better with no problematical valves and higher power to weight ratios but these are virtually unproven in aviation so far. I still worry about piston and ring problems on these designs.

100LL may disappear in a few more years or decades to be replaced with unleaded avgas but tens of thousands of existing aircraft won't be scrapped overnight or fitted with diesels. Let's be realistic here.

True, they have not had much time in aviation - but there are literally many millions of hours of runtime on two-cycle diesels showing their longevity. If there were any basic physics problems associated with the design, we would have seen it by now. Any other issues are simply engineering. One of the biggest problems historically with 2-stroke engines (any fuel) was lubrication of the piston and crankcase. Gas engines made do with putting oil in the fuel and passing it through the crankcase on the way to the intake manifold. Most of the designs on the market now for reasonable horsepower use lube oil in the crankcase just like a 4-stroke gasoline engine. As for the piston and rings, diesel fuel is itself inherently lubricating, though more so with the higher sulfur content of the older road diesels - which brings up the question of whether or not the injector design of the newer diesels will play nicely with the ultra-low sulfur diesels now required in the US, or if a lubricity additive is going to be needed.

Does anyone know the sulfur content permissible (and common) for JetA?

 

[SvingenB]

2 stroke diesel is what powers all large ships, the biggest ones. The reason is that the 2 stroke diesel is the most efficient engine ever produced, and when the engine have to be huge, the efficiency counts a lot. All the marine diesels have valves, so they look like 4 strokes and operate nothing like a 2 stroke motorcycle engine, a two stroke diesel have ordinary lubrication. 2 Stroke diesel have no means of sucking in air, so it has to have a turbo or compressor to blow the air into the cylinders.

edit: found this : http://auto.howstuffworks.com/diesel-two-stroke1.htm

 

[the_other_dougreeves]

And the notion that FADEC is some magic elixir is nonsense. I saw one aircraft that had it installed and it convinced me that it is not worth it. The plane was destroyed in an off-field landing (not many months after first flight) when there was some sort of powerplant/ignition/FADEC issue.

My $25k 2000 Audi works well with EI and a ECU that is essentially FADEC (throttle-by-wire, no less). Why can't we get reliable, affordable FADEC in a 2008 aircraft engine that costs as much as my car? It's not because the technology isn't there....

FADEC isn't magic, it just optimizes the engine automatically. There's a reason all new turbines are FADEC - theirs are more expensive to overhaul / replace.

TODR

 

[Andy_RR]

Actually, to date, the flying diesels are only marginally better in the SFC department over a well set up injected Lycoming running LOP.

But their advantage is they run 'LOP' all the time - climb, cruise, descent, taxiing - whereas your Lycosaurus will only run LOP when you can be bothered to get it set up - i.e. some minutes into your cruise.

The other advantage is that their BSFC doesn't increase as dramatically with decreasing load, so you could in theory reduce your fuel reserves (MTOW overhead!) based on a substantially reduced max endurance burn rate.

A

Edit to say: even using the numbers you state, the average diesel is still running an 8% reduction in fuel consumption over an optimally running Lycosaurus

 

[airguy]

My $25k 2000 Audi works well with EI and a ECU that is essentially FADEC (throttle-by-wire, no less). Why can't we get reliable, affordable FADEC in a 2008 aircraft engine that costs as much as my car? It's not because the technology isn't there....

It's because the NUMBERS aren't there. If you had an aviation engine market that could absorb 50,000 engines per year every year, you'd have companies lining up to do the R&D and compete for the business. Unlike the automobile market, we don't throw our airplanes away after 5 or 6 years, the engine turnover numbers are a small fraction of the automotive world, and the profit potential is much smaller - while the R&D costs remain the same, and then there's FAA certification costs on top of that. The economics are just not there for a full-up new engine development program amongst many top competitors, which is what will be required to keep the price low due to competition.

The winner of this market will be the guys who have the best idea (and practice) for taking a proven existing design and doing whatever modifications are required to get it to WORK in the air. Then let the experimental market do some of your Beta testing while the bugs are being worked out, and the experimental market sales numbers will provide funding to put the final version through certification costs. Only then will the engine maker begin to make money - when the spam cans are flying behind their shiny new toy. That's a long road, with lots of potholes. It's a brave CEO who's willing to drive it.

 

[rv6ejguy]

On my side of the big lake, the real world is different! The normal pilot flying a lycoming the way he/she has been taught, uses about twice the amount of twice as expensive fuel, than the same pilot behind a Thielert.

I have only about 30 hours behind Thielerts, so far I'm happy

The US and Canada are much bigger places than Sweden so we spend hours in cruise, leaned out. Like I said, for flight schools where trips are short, lots of time in the circuit, diesels save a lot more fuel. Aviation applications narrow the gap in SFCs because we normally cruise at or near WOT, so the pumping loss thing is a moot point.

8% fuel savings in cruise are meaningless when the engine is way more expensive to acquire and only lasts less than half as long.

Thielert had the right idea (sort of) to use a proven auto core as a starting point to reduce costs. Unfortunately this engine is just being worked too hard for longevity and the gearbox system and new FADEC has made it perhaps more expensive than a clean sheet design. They may still get it right with the new 2.0 which is to replace the 1.7.

Two stroke diesels are the way to go for aviation. Someone just has to make them lightweight and simultaneously reliable over 2-3000 hours. All aviation diesels will have to have forced induction to even be useful. That is a given. Diesels are complete lame ducks without this on a power to weight basis. I cringe when I read that some new aviation diesels will use 70-90 inches of manifold pressure-very doubtful that these will live a long time.

The FADEC should be very reliable as proven by tens of millions in use in many other engines- you just need reliable electrical systems to keep them working.

I think diesels will be a coming thing in aviation in the future but it will take a while as will the fuel infrastructure at smaller airports.

 

[osxuser]

Lycoming said in 2006 that it would have a "heavy fuel" engine on display the next year. 2007 came and went without a peep.

I beg to differ. They did have a 6-cylinder, horizontally opposed, air/water cooled direct drive drive diesel ON DISPLAY at AOPA 2006 in palm springs! I don't know why it wasn't at OSH, but it was at AOPA. It was tucked away in the back corner of the booth, but it was there...

 

[the_other_dougreeves]

It's because the NUMBERS aren't there. ....
The winner of this market will be the guys who have the best idea (and practice) for taking a proven existing design and doing whatever modifications are required to get it to WORK in the air.

Well, the majority of the R&D is done. One item that needs to be worked out is a knock sensor - not sure how it'd work on an aircraft engine. Everything else we know how to do, right? EI, MAF sensor, multi-point (sequential or simultaneous) and direct (FSI, GDI) fuel injection, O2 sensors ...

What we need to do is the application engineering. Obviously Aerosance and Thielert think that piston FADEC is important and not only are working on it, but they have products on the market (Avgas and Jet-A engines, respectively).

As for the numbers, it's certainly worked for EI systems....

Also, one other data point, the Thielert diesel is to be used on the MQ-1C Predator. This will allow DoD to use JP-8 in the engine, simplifying logistics.

TODR

 

[SvingenB]

Also, one other data point, the Thielert diesel is to be used on the MQ-1C Predator. This will allow DoD to use JP-8 in the engine, simplifying logistics.

TODR

Probably the most important thing Thielert has done right is to have the right product available at the right time. Even with some snags and problems, they are gaining momentum.

 

[rv6ejguy]

Also, one other data point, the Thielert diesel is to be used on the MQ-1C Predator. This will allow DoD to use JP-8 in the engine, simplifying logistics.

TODR

Yes, I read this in Aviation Week a while back. Interesting swap as the engine weighs more than double what a Rotax 914 weighs. I suppose the JP-8 thing is more important than weight to the military.

 

[airguy]

Yes, I read this in Aviation Week a while back. Interesting swap as the engine weighs more than double what a Rotax 914 weighs. I suppose the JP-8 thing is more important than weight to the military.

Another item to consider in this decision would be the turbocharger critical altitude. If the Thielert allows for a significantly higher cruise platform, that's a hard point to argue against for mission profile such as the Predator.

 

[airguy]

As for the numbers, it's certainly worked for EI systems....

Not to beat the subject to death, but the EI market is a lot larger (in numbers of total sales) than a diesel engine. You'll sell a LOT of EI's for existing 100LL engines (retrofit) for every ONE new diesel engine you'll sell. EI's are not "new and scary" technology for most spam-can drivers - diesel engines for some reason are.

 

[the_other_dougreeves]

Yes, I read this in Aviation Week a while back. Interesting swap as the engine weighs more than double what a Rotax 914 weighs. I suppose the JP-8 thing is more important than weight to the military.

If it doesn't have fuel, it doesn't matter what it weighs Remember that the 914 is a very lightweight engine.

Another item to consider in this decision would be the turbocharger critical altitude. If the Thielert allows for a significantly higher cruise platform, that's a hard point to argue against for mission profile such as the Predator.

The MQ-1A and B come with either the 912S or 914. Since the 914 is turbocharged, the Thielert shouldn't have any big advantage over the 914 in altitude performance. I don't know what the available boost is from either one, but I can't imagine that it's all that different.

I'm not sure about the reliability of the 914 vs Thielert. Supply chain might also be an issue for the 914.

TODR

 

[KPmarc]

I beg to differ. They did have a 6-cylinder, horizontally opposed, air/water cooled direct drive drive diesel ON DISPLAY at AOPA 2006 in palm springs! I don't know why it wasn't at OSH, but it was at AOPA. It was tucked away in the back corner of the booth, but it was there...

Sorry. I should have said that Lycoming said it would have an actual, working example and lots of news about the engine for 2007. There was nothing about it at OSH this year that I could see.

I have been told by people who supposely should know that the engine displayed in '06 has been around for awhile, and was probably dusted off to help gauge interest in the project.

 

[rv6ejguy]

I believe the Thielert runs higher manifold pressure than the 914 but I'll try to dig up the actual numbers. The rest depends on the turbocharger and maximum pressure ratio/ N1 limit. The Predator applications apparently run more manifold pressure than civilian 914s but I don't have those numbers. They make more power and are also fitted with EFI rather than carbs. I have heard of case problems with these Rotax engines more than infrequently.

From my knowledge on the subject, 912S and 914 civil engines have far better reliability to date in actual use than the Thielerts. To be fair, the Rotax has many times the flight hours on their designs. The thielert will only get better with time.

This is a big issue with the Thielert- weight. The power to weight ratio is nowhere near that of something like the Rotax nor even that of a comparable hp Lycoming or Continental for that matter. While less fuel required for the mission may offset some of this, payload will still be less with a diesel. Of some help, is the turbo so you can get higher TAS if you want to climb up compared to an atmo gasoline engine.

The Thielert is presently too lame and heavy for an RV. Will Lycoming target the 180-200 hp market with their's or the smaller but more profitable (% wise) 230-300hp market. RV owners may be out of the loop.

 

[penguin]

Aviation 2 stroke with valves

The Wilksch series of engines are 2 stroke diesels that use values and are designed specifically for aircraft. There are only a few flying to date (100 & 120 hp) with a couple in the UK in RV-9s. I believe the speed is comparable to a Lyc powered example with slightly lower fuel burn. As a previous post pointed out a fan is needed to force air into the cylinder on start up of this type of engine, early Wilksch engines had a separate electric blower for use only on start up (heavy), and a turbo for normal use, not sure what they use now.

http://www.wilksch.com/

Pete

 

[rv6ejguy]

Interesting to note the SFC is about the same as a carbed Lycoming. Gonna have to do better than that. It is surprising light however.

 

[Howie]

Diesels in aircraft are NOT NEW. I remember a book by William Green about the Luftewaffe in which a twin engine aircraft was produced with diesels to carry the Olympic flame non-stop to Japan from Germany.

The FW-190 had a single lever control i.e. throttle, prop pitch and mixture all in one, without any chips or electrons.

The big problems I see are weight, vibration and mental. Current diesels weigh too much, shake to much and are hard to convince a current Lycoming/Continental driver to purchase; when the current engines do the job so well here in North America. Go to $7.00 a gallon 100LL and I will be screaming for a new diesel to go in a streched/bigger tailed RV8.

Howie

 

[1:1 Scale]

Current diesels weigh too much, shake to much and are hard to convince a current Lycoming/Continental driver to purchase;

I keep hearing the issue of vibration brought up when the topic of aircraft diesels is on the table. I suspect that this is a stereotype coming from people's experience with truck diesel engines. I can't imagine that there is that much first hand experience with aircraft diesel engines at this point

I'm hoping for a Deltahawk, and in that specific example, with a power pulse every 90 degrees, and a smaller bore with a slower burning fuel, I would imagine that it would run smoother than a typical 320 or 360

 

[Andy_RR]

Interesting to note the [best] SFC is about the same as [the best of] a [lean-of-peak*] carbed Lycoming. Gonna have to do better than that. It is surprising light however.

Yes, I agree with that, but there are two points to consider. The Lycoming degrades its BSFC quite dramatically away from its best point, whereas the diesel is less so. The second point is that the WAM120 is an IDI design, not noted for optimal fuel consumption.

A really good open chamber DI diesel will be around the 0.33lb/hp.h (200g/kWh) mark, which is another leap and a bound ahead.

It is light, isn't it? Imagine how light the installation would have been if it were air-cooled!

A

*tell us how many run carb engines LOP?

YouTube video of a WAM in a LongEze

 

[Dave_Boxall]

The Wilksch series of engines are 2 stroke diesels that use values and are designed specifically for aircraft. There are only a few flying to date (100 & 120 hp) with a couple in the UK in RV-9s. I believe the speed is comparable to a Lyc powered example with slightly lower fuel burn. As a previous post pointed out a fan is needed to force air into the cylinder on start up of this type of engine, early Wilksch engines had a separate electric blower for use only on start up (heavy), and a turbo for normal use, not sure what they use now.

http://www.wilksch.com/

Pete

The Wilksch uses a supercharger to provide pressure to purge the cylinders during startup and idling, at flight speeds the turbocharger provides the pressure and the supercharger idles.

The Wilksch is Indirect Injection because it allows a mechanical engine control unit (the Wilksch gus refer to it as FAMEC) Direct Injection requires an ECU which is a PITA to source & certify. They took a small hit on SFC to avoid electronics.

Dave