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Future Of Diesel Technology  
User currently offlinemaxholstemh1521 From United States of America, joined Sep 2013, 10 posts, RR: 0
Posted (1 year 1 month 2 weeks 2 days 23 hours ago) and read 4622 times:

With all the talk about what will replace 100 low lead for existing airplanes, do you guys think that airframe, and engine manufacturers start pushing diesel technology for new design aircraft? Also, do you guys see more manufacturers doing what Cessna did, and putting a diesel engine on an existing airframe?


It's not a Beaver
27 replies: All unread, showing first 25:
 
User currently offlineJetlagged From United Kingdom, joined Jan 2005, 2565 posts, RR: 25
Reply 1, posted (1 year 1 month 2 weeks 2 days 21 hours ago) and read 4556 times:

They already do. The Diamond DA42 had diesel engines in a new airframe. The single engined DA40 has two versions with a diesel powerplant (DA40-D and DA40-NG).


The glass isn't half empty, or half full, it's twice as big as it needs to be.
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17068 posts, RR: 66
Reply 2, posted (1 year 1 month 2 weeks 2 days 20 hours ago) and read 4520 times:

Diesel engines are more thermally efficient due to higher compression. However this higher compression means they have to be beefier, and thus heavier. Compromises.

There's probably a power and weight above which diesel makes sense, and under which petrol/gas makes sense. Same as there is a point where turbines makes sense.

I was recently told that fifteen years ago you would never use a turbine if you needed less that the equivalent of 1000bhp. Now you're down to 500bhp turbines being a viable alternative to pistons.

[Edited 2013-09-06 06:27:22]


"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlinerwessel From United States of America, joined Jan 2007, 2368 posts, RR: 2
Reply 3, posted (1 year 1 month 2 weeks 2 days 8 hours ago) and read 4371 times:
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Quoting Starlionblue (Reply 2):
Diesel engines are more thermally efficient due to higher compression. However this higher compression means they have to be beefier, and thus heavier. Compromises.

Yes, although the reduction in fuel requirements seems to net that out as a small weight decrease on typical missions. The SMA diesel on the JT-A 182 is only about 35lbs heavier than the turbocharged O-540 it replaces - you'll make that up in fuel weight after about 90 minutes.

Quoting Starlionblue (Reply 2):
There's probably a power and weight above which diesel makes sense, and under which petrol/gas makes sense. Same as there is a point where turbines makes sense.

Doubtless, although the boundary is likely well under 150hp for engines running on non-leaded gas, and so is largely irrelevant for all but the smallest aircraft applications. And the curves are going to be pretty flat in the area, so there will be some overlap. 100LL is a huge issue in most of the world (as in you can't get it at all, or it costs $20/gal), and outside the US and a handful of other countries, unleaded gasoline or Jet-A are really the only viable options. Even in the US, I have serious doubts about the availability of 100LL for a "reasonable" price more for more than another decade or so.


User currently offlineAquila3 From Italy, joined Nov 2010, 273 posts, RR: 0
Reply 4, posted (1 year 1 month 2 weeks 18 hours ago) and read 4038 times:

Wouldn't a Diesel work/be certifiable with Jet-A? It seems to work in some automotive Diesels...


chi vola vale chi vale vola chi non vola è un vile
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17068 posts, RR: 66
Reply 5, posted (1 year 1 month 2 weeks 10 hours ago) and read 3916 times:

Quoting Aquila3 (Reply 4):
Wouldn't a Diesel work/be certifiable with Jet-A? It seems to work in some automotive Diesels...

Jet-A is indeed used in aviation diesels. At airports you only tend to find Jet fuel and avgas anyway.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineMrBuzzcut From United States of America, joined Jan 2008, 64 posts, RR: 0
Reply 6, posted (1 year 1 month 2 weeks 5 hours ago) and read 3853 times:

Quoting Aquila3 (Reply 4):
Wouldn't a Diesel work/be certifiable with Jet-A? It seems to work in some automotive Diesels...

Why not? The remote base I used to work at powered all of their diesel equipment with JP-5, because that is what we had, and it worked just fine for everything from generators to backhoes. IIRC, the JP-5 was actually a better fuel because it met a tighter spec for water and particulate contamination than regular diesel would.


User currently offlinerwessel From United States of America, joined Jan 2007, 2368 posts, RR: 2
Reply 7, posted (1 year 1 month 1 week 6 days 19 hours ago) and read 3766 times:
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Quoting Starlionblue (Reply 5):
Jet-A is indeed used in aviation diesels. At airports you only tend to find Jet fuel and avgas anyway.

Indeed. In fact I'm not aware that any of the aviation diesels are actually certified to run on "normal" diesel fuel (despite several of them being derived from automobile engines). The fuels are quire similar though, and I'd expect the engine to run reasonably well, at least so long as it doesn't get too cold (regular diesel will start to gel up at a higher temperature than Jet-A). The Jet-A will be better filtered and more consistently formulated too.

As a general comment, diesels, like turbines, are pretty adaptable to different fuels, unlike gasoline engines. Pretty much so long as you can get it through the injector, it'll run the engine. For radically different fuels, you may need a different injector and high pressure pump system (for example, if you converted your diesel engine or turbine to run on natural gas), but the bulk of the engine will usually not need any changes. Since the fuel never mixes with air until the very moment it's supposed to burn, there's not that very delicate balancing act performed in gasoline engines, where the mixture has to readily burn, but not during the compression cycle, thus leading to a very narrow set of properties for the fuel. There is really no such concept as "octane" or resistance to predetonation in compression ("diesel") engines (or turbines, for that matter).


User currently offlinenomadd22 From United States of America, joined Feb 2008, 1881 posts, RR: 0
Reply 8, posted (1 year 1 month 1 week 6 days 17 hours ago) and read 3721 times:

When I was in the Coast Guard they used JP-5 for everything. Ship turbines, ship diesels and helo turbines. Really saved on the logistics.
I'm not sure if it's power to weight as much as fuel weight to gross weight. I remember when Burt didn't want to go with a 10% more efficient rear engine on Voyager because it weighed 14 pounds more, until he figured out that it would save him 1100 pounds of fuel.



Andy Goetsch
User currently offlineFlighty From United States of America, joined Apr 2007, 8634 posts, RR: 2
Reply 9, posted (1 year 1 month 1 week 6 days 13 hours ago) and read 3641 times:

Are there good prospects for 4 cyl diesels to get into Cessnas, etc? There has been a lot of progress in turbo gasoline engines as well (run on 91 octane).

It seems like the recent progress in auto industry could spill over to small a/c. Although duty cycles may be too punishing for auto engines.

UPDATE - it seems that Cessna decided to produce only diesel 182s going forward. One"blew an engine" during certification flights  http://www.kansas.com/2013/08/23/296...e-that-made-emergency-landing.html

[Edited 2013-09-09 12:59:33]

User currently offlineDiamondFlyer From United States of America, joined Oct 2008, 1565 posts, RR: 3
Reply 10, posted (1 year 1 month 1 week 6 days 11 hours ago) and read 3592 times:

Quoting Flighty (Reply 9):
UPDATE - it seems that Cessna decided to produce only diesel 182s going forward. One"blew an engine" during certification flights

Incorrect. They are producing natural aspirated 182's on 100LL and phased out the turbocharged 182, to replace it with the diesel.

-DiamondFlyer


User currently offlinercair1 From United States of America, joined Oct 2009, 1327 posts, RR: 52
Reply 11, posted (1 year 1 month 1 week 6 days 11 hours ago) and read 3585 times:
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Described here.

Interesting - they call it a "compression-ignition engine", not a Diesel. Probably so people don't put diesel in it?
http://www.cessna.com/single-engine/turbo-skylane-jta

"The new 227-horsepower compression-ignition SR305-230E-C1 is a drop-in replacement for a turbocharged gas engine, which offers significant fuel-burn reduction. This innovative powerplant design affords you more time between engine overhauls to keep your operating costs at a minimum"



rcair1
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17068 posts, RR: 66
Reply 12, posted (1 year 1 month 1 week 6 days 9 hours ago) and read 3548 times:

Quoting rcair1 (Reply 11):
Interesting - they call it a "compression-ignition engine", not a Diesel. Probably so people don't put diesel in it?

Perhaps, though technically it is in fact a "compression-ignition engine" as there are no spark plugs. You can also run it on other things than diesel.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineokie From United States of America, joined Jul 2003, 3102 posts, RR: 3
Reply 13, posted (1 year 1 month 1 week 6 days 6 hours ago) and read 3510 times:

Quoting DiamondFlyer (Reply 10):
Incorrect. They are producing natural aspirated 182's on 100LL and phased out the turbocharged 182, to replace it with the diesel

The gasoline engine 182 is from what I can tell to be phased out in 2014 and replaced with the T182JT-A.
Cessna does not list the 182 gas burner on their web page at this time, I would not go out on a limb and say you could not order one, you possibly can.
One thing for sure it indicates Cessna's commitment to the "Jet A" burner if they are not offering a gasoline alternative.
Starting price $515,000.

Okie


User currently offlineStarlionblue From Greenland, joined Feb 2004, 17068 posts, RR: 66
Reply 14, posted (1 year 1 month 1 week 6 days 5 hours ago) and read 3500 times:

Now if they could only reboot the 172 diesel project... A 182 is lovely but it is a touch too much airplane for flying schools.


"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlinePhilBy From France, joined Aug 2013, 669 posts, RR: 1
Reply 15, posted (1 year 1 month 1 week 6 days 3 hours ago) and read 3470 times:

Quoting Starlionblue (Reply 14):
Perhaps, though technically it is in fact a "compression-ignition engine" as there are no spark plugs. You can also run it on other things than diesel.

I think that there appear to be linguistic differences to note. Technically 'Diesel' is the term for the compression ignition engine based on the 'diesel cycle' (as opposed to the 'otto cycle') and not the fuel. For example in France the motor is a diesel motor but the fuel is called gasoil. In the UK pumps used to be marked DERV (Diesel engine road vehicle) and only (comparatively) recently have they been marked Diesel. Fortunately a diesel cycle angine can run on a variety of fuels.


User currently offlineStarlionblue From Greenland, joined Feb 2004, 17068 posts, RR: 66
Reply 16, posted (1 year 1 month 1 week 6 days 3 hours ago) and read 3465 times:

You are correct of course PhilBy. Thanks for clarifying.


"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineDiamondFlyer From United States of America, joined Oct 2008, 1565 posts, RR: 3
Reply 17, posted (1 year 1 month 1 week 5 days 15 hours ago) and read 3344 times:

Quoting okie (Reply 13):
The gasoline engine 182 is from what I can tell to be phased out in 2014 and replaced with the T182JT-A.
Cessna does not list the 182 gas burner on their web page at this time, I would not go out on a limb and say you could not order one, you possibly can.

I don't see Cessna abandoning the 100LL 182 market in the US. Quite frankly, these JetA piston jobs aren't going to catch on in the US. They're too expensive to retrofit, especially if there is any chance of a drop in 100LL replacement fuel.

-DiamondFlyer


User currently offlineokie From United States of America, joined Jul 2003, 3102 posts, RR: 3
Reply 18, posted (1 year 1 month 1 week 5 days 9 hours ago) and read 3251 times:

Quoting DiamondFlyer (Reply 17):
They're too expensive to retrofit, especially if there is any chance of a drop in 100LL replacement fuel.

They are working on that.

Quoting DiamondFlyer (Reply 17):
I don't see Cessna abandoning the 100LL 182 market in the US

I did not either but as I posted, Cessna does not list a 182 gasser. My curiosity was trying to figure how much additional up charge there was to go to the "diesel" vs "gas burner" if the factory equipment was the same. It is really hard to get an accurate comparison between aircraft with different avionics and other packages even harder if only one is listed.

Okie


User currently offlineStarlionblue From Greenland, joined Feb 2004, 17068 posts, RR: 66
Reply 19, posted (1 year 1 month 1 week 5 days 9 hours ago) and read 3244 times:

Quoting DiamondFlyer (Reply 17):
I don't see Cessna abandoning the 100LL 182 market in the US. Quite frankly, these JetA piston jobs aren't going to catch on in the US. They're too expensive to retrofit, especially if there is any chance of a drop in 100LL replacement fuel.

Why "in the US"? I know the US is a special market for aviation but economics are economics. If the price of new aircraft and/or retrofit plus the operating costs make it a viable proposition, customers will gravitate towards the diesel solution.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineDiamondFlyer From United States of America, joined Oct 2008, 1565 posts, RR: 3
Reply 20, posted (1 year 1 month 1 week 5 days 7 hours ago) and read 3220 times:

Quoting Starlionblue (Reply 19):
Why "in the US"? I know the US is a special market for aviation but economics are economics. If the price of new aircraft and/or retrofit plus the operating costs make it a viable proposition, customers will gravitate towards the diesel solution.

Because the cost of 100LL is vastly lower in the US than anywhere else in the world. So much so that a majority of light airplanes would never make up the difference in operating costs when you consider that it costs roughly $70,000 USD to retrofit a 172 with a diesel engine.

-DiamondFlyer


User currently offlineStarlionblue From Greenland, joined Feb 2004, 17068 posts, RR: 66
Reply 21, posted (1 year 1 month 1 week 5 days 6 hours ago) and read 3211 times:

Quoting DiamondFlyer (Reply 20):
Quoting Starlionblue (Reply 19):
Why "in the US"? I know the US is a special market for aviation but economics are economics. If the price of new aircraft and/or retrofit plus the operating costs make it a viable proposition, customers will gravitate towards the diesel solution.

Because the cost of 100LL is vastly lower in the US than anywhere else in the world. So much so that a majority of light airplanes would never make up the difference in operating costs when you consider that it costs roughly $70,000 USD to retrofit a 172 with a diesel engine.

Point. In any case I don't think retrofit will be the majority of it. Much more likely to find a diesel in a new build.

There may be a point in the future where dieseltech has progressed to the breakpoint even in the US. Compare with the rise of diesel in Europe, with more than half of cars sold today being diesel. Thirty years ago, this would have been unthinkable but modern diesels make it work. If gas prices continue to rise compared to diesel and diesels continue to become lighter and more efficient.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineFlighty From United States of America, joined Apr 2007, 8634 posts, RR: 2
Reply 22, posted (1 year 1 month 1 week 4 days 18 hours ago) and read 3120 times:

Quoting Starlionblue (Reply 21):
Much more likely to find a diesel in a new build.

Yes. We should keep in mind, Cessna sells new airplanes. That's a tiny, tiny market and they are barely surviving AFAIK with this business model. New aircraft are expensive. But diesel is one way they might maybe compel some sales. The new build market can afford $70k without any trouble.

The secondhand market is another story. It will take decades to clear out the secondhand gas fleets. But the secondhand would want diesel if they could afford it. So these compression ignition planes will have good resale, which ironically means Cessna might sell more new ones. That is how BMW sells cars.


User currently offlineDiamondFlyer From United States of America, joined Oct 2008, 1565 posts, RR: 3
Reply 23, posted (1 year 1 month 1 week 4 days 17 hours ago) and read 3116 times:

Quoting Flighty (Reply 22):
The secondhand market is another story. It will take decades to clear out the secondhand gas fleets. But the secondhand would want diesel if they could afford it. So these compression ignition planes will have good resale, which ironically means Cessna might sell more new ones. That is how BMW sells cars.

Remember, people throw away cars every 10 year or more often. How many cars from the 1980's do you see reguarly driving around? Most of the GA fleet today is at least 1990 or older. A good bit of it is from the 60's and 70's. When an airplane only costs 50,000 to 100,000 used, why on earth would someone spend another 70K to retrofit a diesel engine on when they can just install overhauled for 1/2 that? Other than airplanes that are used to make money, I don't see diesel ever getting a big market share in the GA world.

-DiamondFlyer


User currently offlineokie From United States of America, joined Jul 2003, 3102 posts, RR: 3
Reply 24, posted (1 year 1 month 1 week 4 days 16 hours ago) and read 3087 times:

Quoting Starlionblue (Reply 19):
Why "in the US"? I know the US is a special market for aviation but economics are economics. If the price of new aircraft and/or retrofit plus the operating costs make it a viable proposition, customers will gravitate towards the diesel solution

There are just too many aircraft in GA service to justify change over, especially economically, some old aircraft not counting warbirds or specialty aircraft are 40-50 years old and still viable for use in GA applications.

100LL is facing several problems on the supply side, equipment has to be segregated from manufacturing all the way to the delivery equipment to prevent the tetra ethyl from entering other fuel sources.

GAMI and Swift are both working on a drop in replacement but they are sort of running into the same issues with segregation since auto fuel is starting to be required to contain ethanol. Ethanol is just not compatible with the fuel systems along with some other issues. I think the main issue is that government regulations are holding up the approval process.

Just remember that automobiles are doing just fine without lead, actually better but that is largely due to electronic timing and ignition. although that technology is not available for the old magneto ignition power plants on aircraft.

Just remember to the naysayers, about 95% of the Old Mechanics Tails about the pitfalls of removing lead from Avgas are untrue.

Quoting Flighty (Reply 22):
Yes. We should keep in mind, Cessna sells new airplanes. That's a tiny, tiny market and they are barely surviving AFAIK with this business model. New aircraft are expensive. But diesel is one way they might maybe compel some sales. The new build market can afford $70k without any trouble

I think the big issue has been getting enough aircraft/engine sales volume to distribute the costs of certification and manufacturing.
The list price that I found for a 2012 was about $400K a 2014 Jet A is $515K. That is a heck of a lot more than $70K.

Okie


25 Flighty : Yeah, but Cessna isn't selling new planes to those people at all. Great, hadn't heard of that. E85 conversion has to be be cheaper than a repower.
26 DiamondFlyer : Cessna is barely selling airplanes at all. The only way an engine like this takes hold, is by market share. And with the rate light singles come off
27 Post contains images Starlionblue : Tell me about it. I did my multi on an airplane built in 1957. The first hour or so I cringed during every steep turn, worrying the wing spars would
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