New Lightweight Diesel for LSA & Experimental?



I don't know much about diesel aircraft engines, but I thought the recent Superior Engines of Texas announcement of two new diesel engines was very interesting. This new aircraft diesel engine line was just announced at Sun-N-Fun 2015 . It is an English design ( Britain's Powerplant Developments ). It is a light weight liquid-cooled two-stroke diesel, and uses two pistons in a single elongated cylinder with unusual external crankshafts. The 100 HP version is about the same size as a Rotax.

It does look unusual. I used to own a French car, a Renault R10 and it too looked unusual. I hope this new engines works better than my Renault. The two-opposing-pistons-per-cylinder design is a concept which apparently harks back to German WWII engines used in bombers. They used a 2 piston 6 cylinder design in certain Junkers aircraft engines. Bottom line...I hope this unusual British designed engine works. I will also be curious what these things sound like. Twin piston single cylinder...wow...



The diesel line apparently has been in development for some time. Two models in 100 and 125 HP were announced, with the former supposedly very close to production.

Link: http://www.geminidiesel.aero/aviation

Targeted at the LSA and Experimental crowd, the 100 HP version is reported to be about 10 % heavier than a Rotax 912, and the same size.

( Quick post edit here: One engine s supercharged, the other is turbocharged. I am not sure if the turbo is turbo normalized or higher. Here is a great link of the differences in super vs turbo. http://www.experimentalaircraft.info/articles/supercharging-engines.php. The old WWII Merlin engines were supercharged. So we now have a meeting of German Junkers and British Merlin engine technologies in a 21st century power plant coming out of Texas, USA. Wow again. Up next for Oshkosh 2015 - Di-Lithium Crystal engines for LSA )

If anyone has any comments on supercharged diesels, please share.

Two Models

Gemini 100
• Supercharged, 100 horsepower uniflow diesel engine
• Designed for LSA, E-LSA and experimental aircraft
• Lighter weight with higher torque at lower RPMs*
• Mechanically simpler design with fewer moving parts
• Green operation with much lower emissions
• Runs on Jet A, diesel or bio-diesel fuels
• Up to 20% lower fuel burn than avgas piston engines*
• Retrofittable with many current piston engine designs

Gemini 125
• Turbocharged, 125 horsepower uniflow diesel engine*
• Designed for LSA, E-LSA and experimental aircraft
• Lighter weight with higher torque at lower RPMs*
• Mechanically simpler design with fewer moving parts
• Green operation with much lower emissions
• Runs on Jet A, diesel or bio-diesel fuels
• Up to 20% lower fuel burn than avgas-burning piston engines*
• Easy retrofit with current piston engine designs

Personally I prefer turbo diesel over naturally aspirated diesels. The non turbo engine injection timing is retarded which creates a sharper compression ignition pulse and greater stress. The lower compression turbo engines have greater cylinder volume... More air and fuel...greater power.... What if like to see is ultra high pressure multi pulse per compression ignition. The EE2.0 boxer diesel has it...but the stripped engine tips the scale at nearly 300 pounds.

Wonder what kind of prop the Gemini engine uses....something that can take the ignition pulses? And there isn't anything unique about the uniflow design. Fairbanks Morris produced a variety of engines prior to WW2, many of which are marine application. The 594 class fast attack I served on had a six cylinder 12 piston 750 kW Fairbanks Morris. The power house at the mine initial start up engine was a small Fairbanks Morris opposed piston engine. It also had a hand crank, DC generator end and carbon pack voltage regulator...that was fun to adjust with hot gloves...3/4" wrench...standing on a steel deck....