Diesel motors for planes?

wickedsprint said:
I disagree, there are plenty of low and slow turbine operators using King Airs,and other regional types.
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A lot of people operate a King Air for flights that a Navajo works great for. Our passengers liked the Navajo for that reason - comparable cabin, about 1/2 - 2/3 the cost.
 
Ted DuPuis said:
Yeah, that sounds like with a bit of boost tweaking it would be fine direct drive. The thing to keep in mind is that diesels these days run massive boost levels, and the turbo won't be able to maintain those to the flight levels like your engine can. So a sequential turbo setup will be needed if that's important, especially for pressurization.
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It's an interesting question. The LLY and newer use a variable geometry turbo, I wonder if that couldn't be modified to provide the boost vs. adding a second one?
 
Ted DuPuis said:
A lot of people operate a King Air for flights that a Navajo works great for. Our passengers liked the Navajo for that reason - comparable cabin, about 1/2 - 2/3 the cost.
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Yep, don't get me wrong, turbines have their place, but so do piston engines, and on the whole the guy deciding what type to put on the specific airframe has a good idea what he is doing.


Oh and when was the last time you melted down your turbine wheel during start up on your 310? I have never managed on my 182:dunno: point is pros and cons to every engine choice.
 
kyleb said:
The smallest engine I'm aware of in a King Air is 550 hp. Not exactly a small engine, and not transferrable to the vast majority of the GA fleet.
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PT6 fits a Bonanza airframe just fine.
 
Alexb2000 said:
It's an interesting question. The LLY and newer use a variable geometry turbo, I wonder if that couldn't be modified to provide the boost vs. adding a second one?
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Might be more advantageous weight wise to match a fixed geometry for desired engine rpm and cfm desired.
 
Didn't Thielert come out with a V8 diesel Centurion 4.0 that made 350hp? I think there were even some C206 and light twin STCs. Imagine running a Duke on 25 gph Jet A...

You'd think that intellectual property would be valuable to SOMEBODY...
 
Alexb2000 said:
It's an interesting question. The LLY and newer use a variable geometry turbo, I wonder if that couldn't be modified to provide the boost vs. adding a second one?
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The issue comes into the maximum pressure ratio that turbos can produce. In the olden days, it was around a 4:1 pressure ratio. You've seen some modern designs that can do something like a 5-6:1 pressure ratio.

So, to put that in perspective, a turbo diesel running 30 PSI boost (pretty common these days) is running 3:1 pressure ratio at sea level. By around 13,000 ft you're running a 6:1 pressure ratio. So I think you'll have a hard time getting away from a sequential twin setup if you want to have performance in line with what you find on conventional turbocharged aircraft.

The variable geometry isn't there on modern turbos to provide more maximum boost so much as to reduce spool time for emissions purposes. That was actually the reason the PowerStroke 6.7s had a twin-turbo setup. The little one could spool up to 40 psi boost almost instantly, and the big one kept the power going. Meanwhile, we don't care about emissions, we care about efficiency and performance.
 
Morne said:
Didn't Thielert come out with a V8 diesel Centurion 4.0 that made 350hp? I think there were even some C206 and light twin STCs. Imagine running a Duke on 25 gph Jet A...

You'd think that intellectual property would be valuable to SOMEBODY...
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Yes, Thielert did that. I don't think it ever actually got sold in any aircraft, although it was installed. I never flew their 1.7/2.0s, but I did see them in action and they behaved as you'd expect a modern engine to behave. They had a number of reliability problems, which is pretty much what you'd expect from a new and unproven design. That part never bugged me, but as I recall they were cooking the books which ultimately resulted in their downfall. Their website is still up, though, and says mention of a Duke running on a pair of 4.0s first flown in 2005, but doesn't say much else.
 
I wonder if that turbo has enough headroom to make full boost at 13K without overspeeding?

My duramax at 6K was very laggy compared to sea level.
 
wickedsprint said:
I wonder if that turbo has enough headroom to make full boost at 13K without overspeeding?

My duramax at 6K was very laggy compared to sea level.
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LB7's had a straight turbo vs. variable. They had a reputation for being laggy at higher elevations.
 
Interesting comments so far... Glad to see ALOT of you guys have a good handle on the concept and operation of a diesel..:yes::)..

Without doing a detailed investigation of the specs for the Duramax, I can say the motor looks viable, if it not too heavy. The variable A/R turbo might be sufficient for aviation use as most variable A/R units have the ability to open wide enough to dump excess exhaust to prevent overboost, and still be able to constrict enough to eliminate lag... In aviation, lag is the least of our problems. Properly set up you can delete a wastegate as the V A/R unit can restrict overboosting so that is one component off if it for weight, if it even has one :dunno:...

You can chip the motor for increased output and if the specs given here are accurate I would run it direct drive with a PTO set up to remove thrust and gyroscopic loads off the end of the crank. Another thing to keep in mind is coolent jacket water.. That is a wonderful thing for using to feed remote heaters for the cockpit, and deice surfaces if ya want to get real fancy... If the plane has a Janitrol heater, that whole system can be removed to reduce airframe weight too.

It is late and I am just typing quicky to vent.. I would like to see if anyone has some ACTUAL weight specs for the Duramax. :dunno:..

Carry on..........................................

lil ben.
 
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Ted DuPuis said:
Yes, Thielert did that. I don't think it ever actually got sold in any aircraft, although it was installed. I never flew their 1.7/2.0s, but I did see them in action and they behaved as you'd expect a modern engine to behave. They had a number of reliability problems, which is pretty much what you'd expect from a new and unproven design. That part never bugged me, but as I recall they were cooking the books which ultimately resulted in their downfall. Their website is still up, though, and says mention of a Duke running on a pair of 4.0s first flown in 2005, but doesn't say much else.
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See, you'd think some entrepreneur would buy that IP from the corpse and start their own diesel project based on it. Kind of like starting with a 90% finished part. The big trick to tackle was obviously cost control, but there are plenty of industrialists who are expert in that field.

If I weren't busy right now I'd do it.

Not that the DuraMax solution isn't intriguing, just that the Thielert has flown.
 
wickedsprint said:
I wonder if that turbo has enough headroom to make full boost at 13K without overspeeding?

My duramax at 6K was very laggy compared to sea level.
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This is where you have to size the turbo(s) appropriately. A sequential setup would help.

That said, lag isn't an issue for our engines due to the minimal transients we have to deal with, and big turbo engines we use already have lag at altitude frequently. Once the turbo is doing something it will typically spool up to doing more even faster.
 
Morne said:
See, you'd think some entrepreneur would buy that IP from the corpse and start their own diesel project based on it. Kind of like starting with a 90% finished part. The big trick to tackle was obviously cost control, but there are plenty of industrialists who are expert in that field.

If I weren't busy right now I'd do it.

Not that the DuraMax solution isn't intriguing, just that the Thielert has flown.
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I understand your point, but there's more to it than that. What if that 90% finished part uses pieces that aren't being manufactured or has some critical flaw that prevents it from being certifiable? Reengineering something gets expensive very quickly. Plus, flying doesn't mean a proven design, it just means it worked long enough to get off the ground. :)

I'd go for a Duramax option first. Actually, the idea is pretty intriguing.
 
wickedsprint said:
PT6 fits a Bonanza airframe just fine.
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LOL, yep, and see what it costs to fly across the country in one, and even better, see what your time across 1800 miles is. Reality, you take a TAT turbo normalized one and you'll beat both time and cost before you even consider the capitalization cost of a PT-6. Going faster doesn't mean a whole lot when you have to keep landing for fuel, why do you think only a couple examples exist? If you have a 300 mile mission, ok, but that's a lot of money to spend to save half an hour.
 
N801BH said:
It is late and I am just typing quicky to vent.. I would like to see if anyone has some ACTUAL weight specs for the Duramax. :dunno:..

Carry one..........................................

lil ben.
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Weight could potentially be an issue given the block is still cast iron. Quick searches on a Duramax specific site says the engine weighs 835lbs with full accessories.

Maybe a more suitable alternative is the International (Navistar) VT275. It is a 4.5L V6 with 200HP/440TQ and already has a sequential turbo setup. This was used in International's smaller cabover trucks.

This was also the engine that was rumored to become available to Ford's F-150 line before they ceased the joint-venture. As far as parts availability, etc, the VT275 is shares the same block and components as the International/Ford 6.0L V8 diesel, with two cylinders missing. Most parts aside from internals interchange...
 
guardrail said:
Weight could potentially be an issue given the block is still cast iron. Quick searches on a Duramax specific site says the engine weighs 835lbs with full accessories.
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So let's figure around 900 lbs minus accessories plus cooling. So about a 250 lb penalty for each engine vs a similarly powered LyContiSaur, 500 lbs in a twin.

Designed properly, the plane could handle that fine. Expect it to be something like a Duke. The difference being this plane would burn less fuel.

Maybe a more suitable alternative is the International (Navistar) VT275. It is a 4.5L V6 with 200HP/440TQ and already has a sequential turbo setup. This was used in International's smaller cabover trucks.

This was also the engine that was rumored to become available to Ford's F-150 line before they ceased the joint-venture. As far as parts availability, etc, the VT275 is shares the same block and components as the International/Ford 6.0L V8 diesel, with two cylinders missing. Most parts aside from internals interchange...
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You'd need to boost the power up. That is probably doable with reasonable TBOs for an aircraft application. I'd be curious as to the weight - the PSD6.0 isn't light...
 
Ted DuPuis said:
So let's figure around 900 lbs minus accessories plus cooling. So about a 250 lb penalty for each engine vs a similarly powered LyContiSaur, 500 lbs in a twin.

Designed properly, the plane could handle that fine. Expect it to be something like a Duke. The difference being this plane would burn less fuel.



You'd need to boost the power up. That is probably doable with reasonable TBOs for an aircraft application. I'd be curious as to the weight - the PSD6.0 isn't light...
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Just found the VT275 is ~750lbs...not exactly a lightweight, lol.
 
Weight wise to be ideal, get an aluminum big block engine (I'd go for at least a 502 inch engine, probably 572), put in forged everything with some thick cast iron sleeves, bump to about 18:1 compression with turbos, and make a direct injection setup. 4 bolt mains with all the beefy goodies. Might make 2,000 hours and at overhaul you'd likely need an entirely new engine. Emphasis on might. The other possibility is the cylinder heads blow off.
 
guardrail said:
Weight could potentially be an issue given the block is still cast iron. Quick searches on a Duramax specific site says the engine weighs 835lbs with full accessories.

Maybe a more suitable alternative is the International (Navistar) VT275. It is a 4.5L V6 with 200HP/440TQ and already has a sequential turbo setup. This was used in International's smaller cabover trucks.

This was also the engine that was rumored to become available to Ford's F-150 line before they ceased the joint-venture. As far as parts availability, etc, the VT275 is shares the same block and components as the International/Ford 6.0L V8 diesel, with two cylinders missing. Most parts aside from internals interchange...
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As a current member of the "auto engine conversion" sickness, I can say the REAL weight is next to impossible to determine till someone actually takes a given engine, strips it of all the parts not required for aircraft use, then surgically remove as much weight as safely possibe without hurting durability, and then hang it on a scale for the TRUE number..... When I started on my quest for my experimental, I looked at literally dozens of potential motors and the weights given were all over the map. Some were highly under the estimate, some were WAY over the estimate. Only until you prep one and weight it will you have a accurate weight. IMHO...... Been there..... done that..... Fly it almost every day too...:yes::);)
 
Ben, I was having the same idea yesterday regarding use of coolant for anti-ice, cabin heat, etc. There are lots of potential uses that give advantages.
 
Henning said:
Going faster doesn't mean a whole lot when you have to keep landing for fuel, why do you think only a couple examples exist? .
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More than a few examples exist, the Navy has been using the T34C as a primary trainer since the 70s. It's a tandem seated bonanza with a PT6A.

I'm just saying it fits...obviously at a price.
 
Skylane81E said:
Ted,

I know a guy with a good working relationship with the FSDO...
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Yeah, but the problem is I'd either need to plan on running the 310 as an experimental forever or actually try to certify the damn things. The latter will have tremendous challenges. The former isn't practical, especially since we just bought new engines.

Better would be to start from scratch on a plane as a shed-built. I have an idea on what I'd do. Doubt if it'll happen, though. :(
 
Hell for development purposes a Skymaster might work well, just leave a standard piston on one end.

That and they are cheap!
 
Skylane81E said:
Hell for development purposes a Skymaster might work well, just leave a standard piston on one end.

That and they are cheap!
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Actually that's not the worst idea, but I'd put the diesels on both ends. W&B would be all over the place otherwise.
 
Skylane81E said:
Hell for development purposes a Skymaster might work well, just leave a standard piston on one end.

That and they are cheap!
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Might take some shoehorning, but the SMA diesel that goes in the 182 would probably fit the Skymaster and be appropriately powered. Of course, Deltahawk did this, too. Getting beyond this stage and into commercialization is the trick.
 
So Duramax systems that could be eliminated:

EGR system entirely
Power steering
Cooling fan
Cast exhaust manifolds

Systems optionally eliminated:

A/C

What could we guess that would be ~80 lb.?
 
At least 80 lbs, probably closer to 100. I'd keep the AC on one engine, though. :)
 
The other big weight reducer is replacing the cast iron block with an aluminum block. That's part of what Thielert did with their 4 cylinders.
 
Ted DuPuis said:
Actually that's not the worst idea, but I'd put the diesels on both ends. W&B would be all over the place otherwise.
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I would ballast the light end, one saves money building two prototypes, two you retain one proven power plant.
 
Would have to make sure things get fueled correctly though, perhaps wing tanks of one fuel type and a center tank for the other?:dunno: don't want jet fuel ending up in the gas engine!
 
I'd see the benefit it doing it that way for initial test flights. Then I'd want to put the second prototype on to build hours and durability numbers faster. :)
 
Once you know that it won't dynamically disassemble the moment it gets real world fight loads there are some pluses to that idea.
 
Alright, big question: who's going to fund the project? :)
 
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