Flat 4 or 6 cyl Aircraft Engine

[Andy_RR]

The multi stage injection strategies used on most modern diesels are...

...really only used* for combustion noise reduction at light loads and when cold to mitigate the effects of ignition delay. They generally have a detrimental effect on BSFC, so once you're into the mid-part load to full load region, you're back to single injection only. At all the power regimes an aero diesel is using, multiple injection (a.k.a. rate shaping) would not be used.

*also used for dealing with particulate filter regeneration - also not an aero issue.

 

[rv6ejguy]

...really only used* for combustion noise reduction at light loads and when cold to mitigate the effects of ignition delay. They generally have a detrimental effect on BSFC, so once you're into the mid-part load to full load region, you're back to single injection only. At all the power regimes an aero diesel is using, multiple injection (a.k.a. rate shaping) would not be used.

*also used for dealing with particulate filter regeneration - also not an aero issue.

Ahhh. Interesting, so more for NVH then. Much like timed port injection on a gasoline engine then at higher rpms. Thanks Andy.

An opposed, direct drive engine design will fit the RV cowling easier than an inline design unless inverted or using a high offset gearset. The Sube diesel might work pretty well with an old style pump on it.

 

[Canadian_JOY]

The last issue of Kitplanes showed an airplane completed by a gentleman in Finland - one of their domestic PIK designs. He had painstakenly built the airplane with the intention of installing a diesel. In the end he went with a VW 1.9L turbodiesel and a belt-based reduction drive. Looks like a pretty cool machine, despite the nasty black streaks on the belly. Too bad there's no 6cyl version of this available in order to produce 150+hp...

The Gemini engine is my "pick of the pack" for a light aircraft diesel. The fact that IndUS Aviation flew a diesel-powered airplane to Sun 'n Fun says we're not that far away from viable diesels in the experimental catagory. In the certified world it's going to be a while longer for there to be anything but Thielert ( or its successor) in the marketplace. Continental and Lycoming are missing the boat - they should have an aero-diesel certified and flying by now, but they like the profit margins of the Otto cycle too much and don't want to do any REAL development...

 

[6 Gun]

DIESEL

MY WIFE PUT SOME DIESEL IN OUR LAWN MOWER A 12HP BRIGGS AND YOU COLD NOT TURN IT OFF PUT SOME IN YOUR LCY AND ITWILL RUN FOREVER:

 

[SvingenB]

. Too bad there's no 6cyl version of this available in order to produce 150+hp...

VW (Volkswagen, Audi and Skoda) makes a 2.7 L TDI with 180 hp, a 3.0L TDI V6 with 230 hp and even a V10 TDI with 750 Nm at 2000 rpm.

The 3L V6 has 450 Nm from 1800 rpm and up. This means it has 200+ hp at 2700 rpm, so no gear is needed, only a shaft to fix the propeller to.

 

[mgomez]

Thielert engines run nice

Say what you want about Thielert, but I just flew 12 hrs in a DA42 that had two of their 2.0 L engines. They were very nice. Smooth, quiet, responsive, and only one power lever. No prop or mixture. You feather it with a switch. It starts like a car...a diesel car.

The power lever was just an electrical potentiometer. You move it, and both torque and prop RPM are varied for you by the ECU. At 100 kts (typical pattern speed), the DA42 was at about 37% power, burning 5-6 GPH total.

My RV will have a Lycoming, but boy, those Thielerts were a good match to the DA42.

 

[rv6ejguy]

Yes, they run very nice, just not for that long unfortunately. People associate diesels with running many, many hours trouble free and that has not been the case on the 1.7s to date. Maybe they have improved the 2.0 engines a bunch. Only time will tell. Now the supply of parts, engines and tech support is in limbo. I hope they can sort out the current mess so as not to leave all those customers holding the bag. That would be very bad on .5+ mil airplanes.

 

[bumblebee]

...really only used* for combustion noise reduction at light loads and when cold to mitigate the effects of ignition delay. They generally have a detrimental effect on BSFC, so once you're into the mid-part load to full load region, you're back to single injection only. At all the power regimes an aero diesel is using, multiple injection (a.k.a. rate shaping) would not be used.

two versions of rate shaping have been developed for areo diesel applications throughout the entire power curve. a "7-shot" pulse using piezo injectors on common-rail @ 32000psi and a "2-shot" pulse using a fully mechanical injection pump @22000 psi for use in zero-electric installations.

the reason for reverting to single-pulse in road-going diesels is the very low percentage of time spent at the top of the power curve, i.e. cheap power. why spend $$$ to program an ECU for something that will only be used <1% of total operating life?