The Doyle Rotary Engine

Watching it now. Thanks for posting this.

I must be missing something! How do they cool the thing in real life. Computer animation, I know, doesn't require cooling.

Paul

All:

I found a vid (abysmal quality), of a test of a prototype of the Doyle eng ine.

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Uploaded on Jun 26, 2010 This test occurred December 20, 2009. This was the most recent prototype o f the Doyle Rotary Engine. We were breaking-in the engine by limiting it to 3000 RPM. During the test, Lonny squirted a little bit of oil into the car buretor to protect the seals during break-in.

Sorry for the quality; it was shot on a cell phone.

Shortly after the phone ran out of space for filming, the seals in the moto r dug into the aluminum surfaces and the motor locked up.

We will begin working on the next prototype soon. ========================= =====================

How do they couple it to the drive line?

Gunner

How about attaching magnets around the outside and having it spin inside coils to make a self-contained engine+alternator?

FWIW, it looks to me like this engine violates a basic point of IC engine design for thermal efficiency. By using a separate combustion chamber, it multiplies the surface area relative to the volume of combusted gas. The result is a very high ratio of lost heat to useful heat.

This is what kills the efficiency of flathead engines. This one looks worse in that regard.

Yes, I was thinking the same thing as soon as somebody brought up "how do you cool it?" So, is the combustion chamber in the non-rotating center? it seems like it has an intake/compression piston and a power/exhaust piston. If there's also a separate combustion chamber, than that's THREE places for heat loss!

Jon

It appears to be.

Yeah, it's a split-cycle engine. But it doesn't appear to transfer the unburned mixture to the power-piston chambers. Apparently it burns the mixture first, in a separate chamber, and then opens a port from there to a power-piston cylinder.

It's like a turbine engine with pistons doing the compressing and delivering the power, rather than turbines. Or so it appears.

Yes, with the separate combustion chamber being by far the biggest one, because it not only is losing compression heat; it's also losing heat of combustion.

There have been numerous split-cycle engines, including a number of two-cylinder split-cycle motorcycles, and some were very successful. They can combine pre-compression with as much supercharging as you want. But they compressed the mixture in one cylinder and transferred it to the other, where it was burned. There must have been some thermal loss inherent in the design but at least the *hot* gas was confined to the power cylinder.

This one looks different. At first, when I read "split-cycle," I thought is was really a conventional split-cycle with what amounts to an external swash plate (there have been many swashplate and wobble-plate engines, but they don't use an external cylinder to handle the eccentric drive motion).

But the central combustion chamber make this one an entirely different thing. I wonder why they do it that way? It may be necessary because of the geometric relationships of the cylinders.

Not to mention the lost compression ratio, which in my understanding is another theoretical limit to efficiency in IC engines. The compression (well, expansion ratio, actually) looks pretty abysmal.

This thing looks like it combines the disadvantages of the Wankel rotary and the various sleeve-valve engines with the disadvantages of a Ford flathead, all in a package that's mechanically inconvenient.

Yeah, it would be interesting to know what the compression was in the combustion chamber. It *could* be as high as a normal IC engine, but it looks like that would be very tricky to achieve -- it probably would require that transfer begin well before TDC of the compression stroke, and that the nominal compression ratio of the compression cylinder(s) be a 'way high number.

I'm glad I'm not the only one who's skeptical about it.

I wonder which is the Grand Inspiration that led to everything else -- the cylinder arrangement, or the combustion chamber arrangement?

Just guessing here, but I'd guess it was the balance and compactness enabled by the radial configuration with the external cylinder for transmitting power.

A rotary swashplate engine is more compact, but there is a rotating rocking couple in the balance. I can't do the balance in my head on this radial engine, but, at first glance, it does look inherently balanced.

That..is not a bad idea!! I like it!!

Gunner

I couldn't do the balance in my head either. I suspect that each individual cylinder isn't perfectly balanced, but that the whole shebang comes pretty close.

This is an inside-out version of the Gnome rotary aircraft engine circa 1915 or so with the added idea, from much earlier, of a pumping cylinder. To eliminate the crank, they've got a much larger mass of metal spinning. Power to weight ratio has to be dismal, plus you've a hell of a gyroscopic effect. And you're right, to do this, they've completely thrown away 100 years of combustion chamber shape development.

These engines show up from time to time, going to be the next Best Thing. They usually die because they can't be lubed, can't be cooled and/or suck fuel like demons. Ths one looks like it will probably do all three. About all they're good for, if the promoters are any good, is successfully separating money from the wallets of backers. Just because you can get a 3-D animation cheap these days doesn't mean it's efficient, buildable or durable.

This one was dreamed up by somebody that had an idea, but didn't know I.C. engine history and has no way of knowing how to run the numbers. Another one for a later edition of "Unusual Engines".

Stan

Right. I re-wound that video several times because I couldn't believe what I saw. Was this thing really designed by engineers who understand the Carnot cycle and basic heat transfer??

It looks like a potentially interesting way to make an air pump -- why anyone needs a new pump design, though, I can't imagine. There must be a hundred effective ones already.

Next up: An all-new engine that burns water!

cut

I think I recognize the problem here. These people have the same metal problem that existed in my family for at least two generations. That is the perpetual motion idea. Dad played with various ideas all his life. I still have some of his drawings. He complained about his father's fixation with perpetual motion even to the extent of letting his family starve while he worked with a neighbor developing the next machine.

In all cases, the men were sure they could figure out how to make it work without doing any research. Perhaps lack of education had something to do with it, but I don't think so.

I recall describing some of Dad's machines to a fellow that worked for me. I had no more than begun when he laughed and finished the explanation for me. His father was an engineer in Seattle and had told his son all about people designing and building such things.

I believe the men working on the Doyle engine deeply believe everyone else who has worked on such an engine has made some kind of fundamental error and these guys are smart enough to not make these mistakes, and so will get the engine to be a success.

Perhaps they are German?

Paul

I call it the "This time for SURE!" effect. Sometimes you can improve upon past gadgets with modern materials or construction methods, but the idea has to be sound to start with. This usually happens with smart guys that haven't had an engineering background and don't know that you can't beat basic thermodynamics, you can't even break even. I wonder if they've even cycled it with a electric motor and figured out how much friction they're trying to overcome? Twice the friction per working cylinder, half the power, doesn't seem like a winner to me.

Stan

Hello all,

You guys seem to be very knowledgeable and I would like to have an opportunity to address some of the concerns you have with my engine design.

This would help me identify potential problems that I may have missed.

The prototype in the video has been obsoleted by two more prototypes, the latest of which is a six cylinder with power and exhaust pistons that are 37 percent larger than the intake and compression pistons. This gives us a larger expansion ratio which allows us to use more of the combustion pressure for power.

I do have an strong mechanical background but I am not infallible. The fact that every time I finish a prototype I find areas that can be improved upon proves this.

It is the "This time for sure" effect LOL

I worked for a race engine machine shop for 15 years in their research and development department as their lead engineer.

I worked there until I started an aircraft cnc machine shop, this helps keep the costs of prototypes down and I am able to take my prototypes to the race machine shop

to do all of my testing.

I would enjoy answering any questions you may have.

Thanks Lonny Doyle