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leeschaumberg
05-22-2008, 09:02 AM
Vans recomends the Lycoming 320 & 360 engines because they work so well. This is an undisputed and true fact. The knowledegable knows you can break any thing when every thing is done right. The two main piston aircraft builders are working on the next generation of piston aircraft engines. The flat four engine is the choice for these two. A low fuel consumption is very desireable. The use of petroleum for fuel will be obsolete in the near future. The alternative is a fuel made from plant oil. So considering this the ideal engine would be a flat four, same weight and size of the Lycoming, and capable of burning plant oil for fuel.
Lee

cujet
06-16-2008, 07:24 AM
The alternative is a fuel made from plant oil. So considering this the ideal engine would be a flat four, same weight and size of the Lycoming, and capable of burning plant oil for fuel.
Lee

I would suggest that the opposed 6 cylinder direct drive diesel, of similar HP/displacement as your above 4cyl, is a better choice for prop resonance and crankshaft torsional issues. Including the all important seat of the pants "feel" of vibration issues.

I have 2 Volkswagen diesel cars. Both have serious vibration issues. Yes, the engine mounts hide the vibes. But, the vibes are still there.

I had always wanted to convert a 6 cylinder lycoming 540 to a diesel engine. My thoughts were to produce a water cooled, 4 valve cylinder assy (3 integral cylinders) with much less bore diameter than the Lyc. It would bolt right on. The 2 mags would be replaced with 2 injection pumps. Each cylinder would have 2 injectors.

To the bottom of each "triple cyl" assy would directly mount a small turbo, this would place it high enough to drain into the sump without a scavange pump.

The twin turbo, 400 cubic inch, 6 cylinder diesel engine would produce about 250HP at 2500RPM and maintain that HP up to a fairly high altitude. Giving excellent cruise performance and economy.

rtry9a
06-16-2008, 07:44 AM
I think your basic assumptions are faulty ...

Why pistons at all- they result in vibration and unneeded internal stress compared to other alternatives?

Why diesel? It requires a lot of engine weight to withstand the torque reversals, it is polluting (dirty burning under high loads, and it is significantly more expensive than avgas and mogas.

John Clark
06-16-2008, 10:27 AM
I think your basic assumptions are faulty ...

Why pistons at all- they result in vibration and unneeded internal stress compared to other alternatives?

Why diesel? It requires a lot of engine weight to withstand the torque reversals, it is polluting (dirty burning under high loads, and it is significantly more expensive than avgas and mogas.

I think you missed Lee's point. The assumption he is making, and I agree, is that there might not be any avgas or mogas to use in the future. The diesel will run on a variety of fuels including Jet-A (which will be around longer than Avgas due to economic realities) or vegetable products.

John Clark
RV8 N18U "Sunshine"
KSBA

cujet
06-16-2008, 10:42 AM
I think your basic assumptions are faulty ...

Why pistons at all- they result in vibration and unneeded internal stress compared to other alternatives?

Why diesel? It requires a lot of engine weight to withstand the torque reversals, it is polluting (dirty burning under high loads, and it is significantly more expensive than avgas and mogas.

OK, I see your point. I wish you all the best luck with your engine design. One day, someone (it could be you!) will come out with a great solution. I am old school, and my thinking clearly shows that.

However, in today's environment, fuel economy is quite important. It is kind of hard to beat the BSFC of a diesel, not to mention the MPG. Remember that diesel/jet fuel has more energy per gallon and diesel engines have better BSFC per pound. That is a double positive.

Mike S
06-16-2008, 10:48 AM
I had always wanted to convert a 6 cylinder lycoming 540 to a diesel engine. My thoughts were to produce a water cooled, 4 valve cylinder assy (3 integral cylinders) with much less bore diameter than the Lyc. It would bolt right on. The 2 mags would be replaced with 2 injection pumps. Each cylinder would have 2 injectors.

To the bottom of each "triple cyl" assy would directly mount a small turbo, this would place it high enough to drain into the sump without a scavenge pump.

Good thinking, I like it.

Not too sure if water cooling is needed------lots of air cooled diesels currently in existence for a variety of uses.

My biggest concern would be the strength of the remaining Lyc parts.

cujet
06-16-2008, 10:59 AM
Good thinking, I like it.

Not too sure if water cooling is needed------lots of air cooled diesels currently in existence for a variety of uses.

My biggest concern would be the strength of the remaining Lyc parts.

Water cooled to allow the 4 small valves, without overheating between the exhaust valves.

The smaller bore would reduce the loads on the remaining Lyc parts by quite a bit. However, you are right, high compression puts higher loads on the parts. Going from a nominal 9 to 1CR with a 5.25 inch bore to 17 to 1 with a 1/3 less displacement (due to bore) would still produce higher loads during the compression stroke. However, compression is not the highest load the rods/bearings experience. Inertia is, by far.

The reason for dual injectors was not for redundancy (although that could be incorporated). It was for a mechanical means to provide a small pilot injection to reduce stress. In other words, the first injector would be smaller, atomize better, inject earlier and provide only a fraction of the required fuel.

The 2500 RPM limit was also to reduce stress.

I suppose the goal would be to use as many off the shelf components as possible. Cummins turbo diesel parts maybe?

gasman
06-16-2008, 11:32 AM
IS NOW A GOOD TIME FOR THIS MOTOR?........ http://bourke-engine.com/ani.htm

John Clark
06-16-2008, 01:24 PM
IS NOW A GOOD TIME FOR THIS MOTOR?........ http://bourke-engine.com/ani.htm

Mmm, right. Brought to you by the fellow who's patents expired before anyone showed any interest. But not to worry, he has a new product "that will increase your fuel mileage by at least 22%. Please excuse me if I don't hold my breath waiting for this breakthrough.

John Clark
RV8 N18U "Sunshine"
KSBA

smenkhare
06-28-2008, 06:07 PM
Why not plug in one of these from Sandia national labs?

http://www.switch2hydrogen.com/

az_gila
06-28-2008, 07:35 PM
Why not plug in one of these from Sandia national labs?

http://www.switch2hydrogen.com/

Hope it works better than the Santa Clara buses running on hydrogen fuel cells...:)

http://www.greencarcongress.com/2008/02/transit-agency.html

This bit was interesting. I guess it's hard to keep hydrogen in it's place.

An additional cost was fuel loss during fueling. The fueling facility (which had to be leased, for an additional cost) was consistent and operated with an efficiency of approximately 50%?i.e., for every diesel gallon equivalent (DGE) of hydrogen dispensed into the bus, one DGE was lost into the atmosphere. This effectively doubled the cost of fuel.

jonbakerok
06-29-2008, 10:19 AM
Why? There is no shortage of petroleum in the foreseeable future, only the will to develop it -- and only in America. Right now there is no substitute for gasoline. Plant-based oils? Good idea. Let's burn our food instead of eating it! All the poor starving folks around the world will really love us for turning Kansas into a fuel dump.

But don't get me wrong -- I'm not saying the gasoline engine isn't due for replacement --and much sooner than we now imagine. Electric motors make much more sense, especially for prop aircraft. They are light, quiet, and compared to pistons, last virtually forever. The power they use can be generated from nukes, sunlight, or our almost unlimited supply of natural gas and coal. The only problem is the weight of the batteries and the recharge time. The solution to that problem is just around the corner. It's a new kind of super-capacitor that is currently under development and less than five years from hitting the market full-scale.

If gasoline becomes hard to get, it will only be because nobody needs it any more.