I LOVE DIESELS... I have owned a VW TDI JSW with DSG (had to get my acronyms out) for over 10 years. I get 50MPG highway, 700 miles per tank. Tons of low end torque which makes it fun to drive. It is 2.0L CR (Common Rail) Turbo I4, 140HP and 240 ft-lb torque. I dislike little 4 banger gas cars. Hey they get the job done and are economical, but low power. You need to Rev'em really high to get it going. The sound little 4cyl gas cars make winding them out not great. The VW TDI Turbo Diesel sounds great torque starts just above idle and peaks at 1700RPM and is flat (controlled by ECU). It could make way more HP and Torque with reprograming the ECU. It is like driving a V6 gas engine. The VW TDI can do 70MPH all day at a little over 2200 RPM.
With that said DIESELS IN AIRPLANES? Kind of a mixed bag but mostly sad story or at least promises not realized. Diesels superiority in trucks, heavy equip, ships and Subs well known.
DH 180 Deltahawk Diesel, V4 2-stroke diesel? They have been right around the corner from certification for a decade. Always next year. Have not heard anything from them in 3.5 years. To their credit they did make engines and then started over. Also they made prototypes and flew them in planes like a Velocity, Cirrus, RV I recall. I also recall they were looking for volunteers to put their FWF package on their RV (new engine mount, cowl, cooling, exhaust, prop) for about $80K (not sure) to be a beta tester. Wish them well.
https://youtu.be/JggCgKau1m0
https://youtu.be/3GT8Ueaug7A
Remember Gemini years ago? Neither do I. Superior shelved it. The High Pressure Fuel pump development & tooling was too high, millions. Web site is 404.
"Gemini Diesel aircraft engine from Superior Air Parts" (100HP 2 Stroke 100HP for LSA's)
https://youtu.be/VZA4S5KkI5g
"Gemini diesel aircraft engine available on American Legend Cub" (this plane was trailered to show and never flew then or later)
https://youtu.be/4pua-yomCI8
Good video of 8 diesels in aircraft and military drones. Lycoming and Continental both have or had diesels but the civilian market was not there. I believe Cessna for short time offered a C182 Diesel option but the higher cost and the benefit was not enough to make people want to buy them.
"8 Of The Few Diesel Aircraft Engines Ever"
https://youtu.be/WUCwusR7ILw
DIY Automotive Diesel conversions that were either OK (I think) or failures.
One was the "Raptor" famous or infamous plane development which was documented on Youtube over many years. Videos are still up. Despite his failure he really gave it a go. The plane flew and the designer, builder and pilot was getting the bugs worked out. It used a VW 3.0L V6 TDI Turbo Common Rail (CR) Diesel engine. However a failure in his PSRU caused loss of power and he made a successful forced landing in a field. He was unhurt. He shelved the design, but after a year hiatus from making videos he recently post his totally new design. It is a paper airplane, concept not an actual plane. It's on YouTube and will use electric engines, ducted fans, powered by APU's. In the case of the Raptor with the V6 Diesel car engine, like so many auto engine to plane conversions, it made way less thrust than predicted, was SLOW, very heavy and wickedly unreliable due to his unique PSRU.
The PSRU all too often is the Achilles heel in car engines in planes. Because car engines are designed to make power at higher power, and props are not efficient at those RPM's you need a speed reduction, or Prop Speed Reduction Unit (PSRU). NOT ALWAYS but the PSRU has been the problem with auto to plane conversions. It can "work" but it is another failure point or points if we are honest. The problem with many reduction drives is they can't support hydraulic props or aerobatics. However Peter (Raptor Designer) had a flat belt reduction and a very creative solution to use a hydraulically controllable prop. He got it to work, for a short time. The first loss of power he blew out an oil seal in his PSRU. Since engine oil was being used for the prop (bad idea all around, especially diesel oil which gets very dirty very fast) he lost all engine oil. With blown seal, engine was toast when oil pressure was lost. He made a successful dead stick landing back at the airport! There are videos of this. So he replaced the trashed engine with another and made changes to seal. He went flying again and flew off his Phase I, 40-70 hours. All was good unit the second PSRU failure, A shaft keyway drift pin in PSRU failed, sheared. That one resulted in the off field landing. Plane was damaged but Peter walked away with out a scratch. It is too bad he did not use an electric constant speed prop from the start. The belt drive PSRU had was in concept was OK, but execution had belt tracking issues and many other issues. Too many issues to be reliable long term. Service life would be very short. Bottom line the plane was not viable and ocean from his predicted performance. It was at gross weight with one pilot and half fuel. It was a 4 seater design. He gave up on that design and now after a year just came out with his new design, electric motors being driven by diesel powered generators or APU's.
The other DIY diesel in a plane, was also used a VW. This time an I4, 1.9L Turbo Diesel (not TDI or CR). It was the predecessor to my VW I4 2.0L TDI CR "clean diesel". The previous engine was way more diesel simple, but with lower HP (110HP verses 140HP) and more emissions. As much as I love my 2.0L TDI CR engine I have in my car, I would not use it in an airplane. Even though the 2.0L TDI CR diesel is a better engine as far as power and lower emissions (in a car) it is WAY more complex and requires a very high pressure Common Rail fuel pump (subject to fail), electronic piezo injectors and ECU. Good luck making your own redundant ECU. All good but just way complicated and very electronic. This effort was done in Europe (Finland I believe). It flew in a Cessna 172. I don't know status but there is a Youtube video of it flying 11 years ago. He claims it makes 180HP. In a car it is rated for 110HP. I suppose if he upped the turbo boost and increased RPM's he'd get 180HP? However like so many car to airplane conversions, gas or diesel, the promised power or thrust is often less, way less than promisedor hoped for. There is clearly a PSRU from one of the below videos. It looks like a massive gear drive. Austro 2.0L Diesel is rated at 180HP, so may be he got 70HP more than what VW rates it at. The aircraft performance, weight, I don't know. Only two videos 11 yrs ago. He did post videos 4 yrs ago of drone footage around his property. Looks cold in Finland, burr.
https://youtu.be/VMMRWOO0bmc
https://youtu.be/mgI4vJZZv48
State of Diesels in aircraft.
The current winner and champ of diesels in GA planes is the Austro 180HP 4-stroke Diesel (core is out of Mercedes Benz). It flies in the certified $1.2M D62 Twin by Diamond. Seems to be working. Not powerful but gets the job done. The D62 has a small 4 place cabin. Very slick looking plane. Whole plane is designed for this engine. There have been a few D62 accidents in the short time it has been out. There were also many Diamond D42 diesel twin accidents as well. The predecessor used a different diesel engine and installation design. The D62 accidents are likely from dumb pilot tricks. One was mismanagement of electrical system where pilot jump start stated totally drained dead batteries and then went flying. Another might have been fuel starvation. Not the engines fault but all these automotive engines need an ECU and creating redundancy and a totally reliable electrical power system is a challenge. IT CAN BE DONE, but it is a failure point or points. Apparently Austro has done a good job. Perfect? Well it better be close to perfect for about $1.5M.
I choose to live in 2019 prices in my head. I can't deal with current prices. If you had your heart set on a TWIN, many used twins with two 180HP Lycs to 350HP Continentals can be had for a fraction of the price of a D62, with much bigger cabins, payload and speed. Yes you burn more fuel, but $1.2M can buy a lot of fuel. Also everyone knows how to work on a Lyc or TCM. It is a hard sell to get diesels into GA planes.
BOTTOM LINE I LOVE DIESELS.... However it seems only $1.2M twins (more like $1.5M plus with options) and military drones have caught traction. Diamond did put the diesel in their single engine DA40. Not sure about cost, sales and performance compared to the gas powered version. The problem with diesel or any car engine, you add water cooling, redundant electrical, PSRU you get extra weight. For it to really be integrated well the plane has to be designed from the get go for the engine to make it viable. A turbo or supercharged diesel (normally asperated diesel is a no no) operate at insane cylinder pressures and therefore need beefy cranks, crank cases, rods, pistons and cylinder heads... They weigh more. However they are much more efficient (and durable if run at low diesel RPMs). Only 12%–30% of the energy from the fuel you put in a conventional vehicle is used to move it down the road. Diesel is around 70% efficient or at least 35% or more than the most efficient gas fueled ICE operating at peak economy. Diesels just run efficiently all the time.
This video goes over WWII Diesels WWII time frame in Ships and Subs... It starts with history and goes over many variations of diesels they tried. I had no idea of how many interesting variations of diesels existed. The efficiency of these engines were very high.
https://youtu.be/WUCwusR7ILw
