Rotary diesel?

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Kram

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Nov 30, 2012
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No, just business, just a matter of money flow...


JCP
Correct, you would be surprised at how much money "the Big Bad Three" (along with the others) throw at patents and licences every year but nearly always at the end of the day there is no profitable way forward for those ideas. Usually the patents and licences are purchased in order to see if the idea can be developed, not quashed by the MIB.


Anti-Wear Coatings, Heat Rejection Coatings, and Seals have all improved. Perhaps it is time to revisit a Wankel-Diesel !

JCP
Nope, simple case of the thin crescent shaped combustion chamber offering far too much surface area soaking up too much heat in a rotary to be successful as an efficient diesel. Check out the Rolls Royce diesel wankel to get an idea of whats required to get the combustion heat, suddenly all thr rotary's advantages just went out the window (along with the apex seals :)).
 

Jaxx

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Dec 16, 2012
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fayetteville nc
When we built working models of new design dieseling engines there was a lot of fuel mixing to get them to run ..
we had spark plug.. glow plug.. air injectors.. and fuel injectors all in the same head..
My point is the many variables that can be tested..
I personally do not think a Wankel engine can run well as a diesel..
 

Rotarywheelmen

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Mar 10, 2013
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sacramento ca 95670
Hello everyone,Im new don't own a plain or have the means to,my speeling is bad and grammor worce, but I own and have been driving a almost 100% diesel powered rotary rx8 and need some advice on eliminating spark. I have some ideas and I think the renesis solves many of the prior problems discussed above with two cooling jackets more ports and higher revs. Now torque I belive is an issue between us am I right, please anything possitive would be greatly welcomed as support is lean at best here at home.
 

wizzardworks

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murfreesboro NC USA
Rotarywheelmen, I am building a four rotor with my own aluminum end housings of 398 aluminum (17% silicon carbide alloy) and in anticipation of possibly running on diesel I have included mounting bosses for direct injection thru the side housings. Getting fuel sprayed in is the first step. The second is the mindset of the rotary RPM. The balance point where gas pressures and centrifical force are
equal is 6200 RPM on the stock Mazda RX8 and would be higher on a diesel. I remember the RC aircraft diesels which had adjustable compression. Turn it in to start and as it heated up screw it out for less compression and more speed. With more RPM there is less time for heat loss thru the side housings and rotor. In a post above it was suggested that the large surface area of the moving combustuion chamber would transmit too much heat away making it difficult to ignite diesel fuel. I disagree with this notion by intuitionn alone. A four stroke diesel has 1 hot power stroke with 3 strokes to cary heat to the water jacket.The Wankel engine has the exhaust and intake strokes occuring while the other rotor faces are fireing. Also on a piston diesel the cylinder wall adds considerable surface area and is water cooled.One third of the Mazda heat rejection is thru the oil cooled rotor which has a lower transfer rate than water cooling. Second point is that the 8 pound rotor is what limits the RPM on the Mazda engine. If I get serious about running on diesel I would carve ceramic rotors on my CNC machine which would transmit almost no heat. Think of the ceramic tiles the space shuttles were covered with.....machined ceramic blocks. For several years pistons have been used on road tractor diesels which have ceramic tops so the temperature and shock of the diesel fireing would not seem to be an issue. I am waiting for Ford and Mazda to make available in the US their laser ignition as used on the Mazda 16B and some sky-active engines but not available in the US at present. The DD15 diesels have a turbocompounding setup which is geared to the crankshaft for starting boost and as the exhaust gets flowing to spin the turbo, excess power is sent back to the crankshaft recovering 8% power from the waste heat as useable torque. There is a double expansion Wankel (rotors in series) which recovers exhaust residual power on one face with the other side of the housing supercharging the first stage rotor. I think it is a marine engine, ciurrently lost on 11.5 terabite of hard drive of this computer.
When you say you drive an almost 100% diesel rotary would that mean a mix of diesel and 87 octyane gas with spark ignition? My misspelling is due to an enthusiastic keyboard that likes to add a b or d or change to caps just to make things interesting.
wizzardworks
 

lehanover

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Jul 12, 2005
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Hebron Ohio in summer. Zephyrhills Florida in wint
Hi All: I'm not sure if this is the right place to ask but,does anyone have any information on a rotary engine that will run on diesel fuel. I have been told that there was something at Oshkosh a while back. I haven't been able to find any info on who it was or what the details of the engine were. Regards...........Reg
The Britich developed a very nice diesel rotary using a large displacement rotary as the compressor and a smaller as the diesel engine. Much too heavy for aircraft use. But serviceable for stationary power. Lynn E. Hanover
 

cheapracer

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In a post above it was suggested that the large surface area of the moving combustuion chamber would transmit too much heat away making it difficult to ignite diesel fuel. I disagree with this notion by intuitionn alone.
Disagree all you want but you are technically and historically 100% wrong, surface area and combustion shape is just one of many big issue with rotarys and that's why there are no diesel rotarys. There are other very major issues as well, enough that no one makes one and unless some technology dramatically changes, never will..


A four stroke diesel has 1 hot power stroke with 3 strokes to carry heat to the water jacket. The Wankel engine has the exhaust and intake strokes occuring while the other rotor faces are fireing.
Also on a piston diesel the cylinder wall adds considerable surface area and is water cooled.One third of the Mazda heat rejection is thru the oil cooled rotor which has a lower transfer rate than water cooling.
A piston engine is by far more efficient than a Wankel is, it provides energy to drive the piston far more effectively per charge than that of a rotary's partly due to it's by far smaller internal surface area than the rotary's.

FWIW, a 2 cylinder, 4 cycle piston engine is equivelent to a rotary in terms of 1 firing pulse per 360 degree crankshaft rotation or a single cylinder 2 stroke.

While a rotary has packaging advantages of a "3 in 1 piston" (loosely speaking), that very packaging causes many of it's main disadvantages but no need to explain that to a guy building a 4 rotor wankel of course.
 

Hofacker

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Aug 28, 2006
Messages
5
NASA did one like this back in the late 70's or early 80's I think. Glow plug in the trailing spark plug hole, high pressure injector in the leading spark plug hole, turbos bolted to the intake manifold - no throttle plate - more fuel = more power. I've been looking at the NASA archives for a tech note or documentation so far no luck. I think seals may be an issue at the high compression ratios. The concept still fascinates me. I'll keep looking. It would also seem there must be some fundamental flaw since it hasn't been done yet and it looks such an obvious thing to do.


The German company "WankelSuperTEC" appeared to have an approach to a Wankel-Diesel that looked very promising.

Direct Injection with a Spark plug to get it started.

Once Turbo spooled up under load, would run as a Diesel.

Turbo boost (2:1 to 3:1) plus Wankel compression (8:1 to 9:1)
got you into normal Diesel compression ratios.

No Intercooler, hot compressed air out from Turbo further compressed and heated by Wankel compression cycle to diesel ignition temperatures.

Hence 2 stage compression, and 2 stage expansion.

At light load (i.e., low boost) I've heard that it needed spark to run smoothly. (or a glow plug)

Project either ran out of money or went black and may now be powering drones.

JCP
 

SHIPCHIEF

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Great Northwet
The C-W, John Deere, Rotary Power International SCORE 580 engine was a diesel direct injected Wankel Rotary engine.
It was intended to have a high power to weight ratio for use in battle tanks.
It lost funding during the military cut backs of the Clinton Administration.
Here is a link to a discussion of the slow painful death:
Rotary Power International? - RotaryNews.com
The Mazda 13b type engine might be the 70 series engine mentioned in the link, one smokey example being built.
 

wizzardworks

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What is the problem with having spark plugs on a rotary diesel? Seems like a small compromise and could improve BSFC. In its normal configuration the heat of compression
raises the air temp above the flash over point of the fuel and the fuel ignites as it is injected. This makes the fuel injection timing an important issue where with spark
ignition the fuel and air could be mixed during the compressdion stroke. The spark would then start a conventional flame front heating the mixture as it propigates. A
turbocharger seems like an excellent choice on an aircraft engine but I was thinking the exhaust heat could be used like a cabin heat muff on the diesel intake to
preheat the air so that less comression is needed to get the air above the flashover point. This seems more effective than heat transfer from the cylinder wall and
head which are water cooled to a surface temp below 400 degrees F. I am also not convinced by the argument that a wankel combustion chamber particulary one
smaller to raise compression is relevent. Some diesel engines like Internationl Harvestor had a prechamber in the head to start a flame front but the majority don't
have anything but a flat space between the piston top and head. Personally I don't have a problem with starting a wankel diesel with a separate injector that
injects gasoline to get up to temperature. No different than a modern 2 stroke having an oil injection pump to avoid premixing fuel and oil. The real goal is the
ability to burn jet fuel or kerocine in parts of the world where gasoline is extremeny expensive or unavailable because engines run on soy bean oil.
wizzardworks
 

Jaxx

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Dec 16, 2012
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fayetteville nc
I hold a patent on a rotor diesel..
Working design is near complete..
The components were machined but injection and MF clutch programming is yet to be done..
It is super charged and multi fuel mix capable..
It was not designed for aircraft..
Power torque curves studies are similar to electric motor..
 

PMD

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Apr 11, 2015
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Martensville SK
If my horrid memory can serve me this one time: I seem to recall that the Norton twin-rotor based engine that (Continental?) was being developed first as a drone engine, but secondly as certifiable genav power was advertised as multi-fuel, and fully capable of burning D2 or Jet A/A1.

Now, if anyone out there is REALLY serious about burning distillate fuel in a rotary combustion engine, I suggest the contact Dr. Mark Cherry regarding catalytic igniters. He has taken (at OSH BTW) a dead stock gasoline recip engine, flown it into OSH on gasoline, pulled the sparkplugs, magnetos and harness, installed a set of his catalytic igniters (a LOT more technology than just a glow plug), drained the tanks of avgas, refilled with Jet A, started up and flew it around in front of hundreds of witnesses. Required aspirated charge (long story, but it does) but that could be used for starting by changing injection timing possibly, but it should be able to run on a compression ignition cycle once one had enough cylinder pressure from boost.

BTW: the purpose of that demonstration was to show how the tens of millions NASA piddled away to the big name engine guys to develop alternative fuel engines was all window dressing for NASA to look as if they gave a flying purple **** about Genav at all. He told me at the time, that their efforts would result in no engine being manufactured (prototypes, yes, production no) and that he could meet all of the requirements from NASA with nothing more than a handfull of igniters and running 14 VDC to them.

Last time I visited with him, he was in Sandpoint ID, so not sure if he is still there or the address and telephone in this link is still valid (too late at night to test) http://www.growthconsulting.frost.com/web/images.nsf/0/40ACFA3E8E368EAA652571480025194B/$File/TI%20NA.htm
 
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