Eggenfellner Engines - Technical Only

[gmcjetpilot]

Form, Fit Function

This thread has been very informative but I have a few questions.

As I see it, there at least five ways to connect a prop to the power source:

1) Direct Drive
2) Gear Drive
3) Belt Drive
4) Shaft Drive (Quill shaft)
5) Viscous coupled shaft (Including air drive)

Bill you seem to have more answers than questions. I'll comment on your analysis summary.

Direct drive: I always like the Corvair or VW engine for conversion, but these are lower HP applications. The direct drive installations with these air cooled horizonatlly opposed engines tend to have crank issues, verses ones that use a reduction drive. Either way they are low HP applications, not fire breathers. Direct drive is lighter and simpler and works for the Lyc and TCM, designed from scratch to be direct drive.

Belt drive: This has always been attractive to me. Belted Air power has always had a pretty good design. It's not a forever drive but its about as simple as you can get. The material technology of the belts are pretty amazing. Fool proof or will never fail? No, nothing is that.

"Viscous coupled shaft (Including air drive)": The only one I know of, is the most successful engines in history, the Pratt & Whitney PT6, but it's turbine. It is one of the most reliable and well regarded engines in the world.

Now what?

Back on Eggenfellner PSRU, the envelope, amount of reduction, HP and geometry almost requires some kind of gear drive due to: FORM>FIT>(follows) FUNCTION. The debate is not can it be done or should it done, but how can we gain confidence and improve geared PSRU's (if they need improving), down the road. I give up , but I'm leaving it to people that are smarter than I to figure it out. I'm cheering Jan and you all on.

 

[rodrv6]

Jan, is the gear ratio the same in a Gen3 -v- Gen1?

The Gen1 and Gen2 had the same ratio, about 1.86/1. The Gen 3 is 2.02/1 (or thereabouts).

 

[Geico266]

The Gen1 and Gen2 had the same ratio, about 1.86/1. The Gen 3 is 2.02/1 (or thereabouts).

That explains the added HP. Spinning faster gets in the higher HP range = better climb performance. The prop has been adjusted to new parameters also so the old set up may not have been optimal.

 

[Geico266]

My buddy is having a starting issue I would like to discuss. 2.5L cold starts only, the engine starts but gets slow then dies. Restart is the same, but as the engine warms it runs fine. No engine lights, have not pulled codes.

Any ideas?

 

[DanH]

<<That explains the added HP. Spinning faster gets in the higher HP range = better climb performance. The prop has been adjusted to new parameters also so the old set up may not have been optimal.>>

Larry, ask him what RPM he had in climb previously vs what RPM he sees now. Might confirm the following.

If you assume 2700 prop RPM is desired and you want to be close to max HP engine RPM at that prop RPM, then the new 2.02 ratio is a pretty good choice. 5600 engine RPM is max HP (165) per the 2000 Legacy brochure. 2700 prop RPM x 2.02 would be 5454 engine RPM, about 156 ft-lbs torque, and about 162 HP. Jan picked well.

With prop RPM again at 2700, the old 1.86 ratio would have put engine RPM at 5022 and torque at 159 ft-lbs, or 152 HP.

The above values assume a perfectly flat torque curve, and of course, OEM sales brochure torque and HP numbers. OEM numbers aside, the HP difference would be a bit less if the torque curve really is a curve.

Jan, how about telling us the actual torque?

 

[Sam Buchanan]

Jan, how about telling us the actual torque?

 

[DanH]

Sam, some of us hoped to get facts on the table, plain physical reality viewed without emotion and nonsense, the kind of thing that keeps airplanes flying. If you're going to deride a question as mundane as torque, there is not much hope left for a solid technical thread. I decline to beat that horse.

Jan, thank you for your responses; I'll visit the booth if I make S&F. And everyone, thank you for your restraint. It was for the most part a pretty good experiment.

 

[Jconard]

Well,

I for the most part am disapointed. Very little if any technical information shared.

Many claims were made. Many attempts at clarification were dispelled without clarity.

What was to be an open discussion of technical details ultimately became "a discussion of how great these packages run". Mutually exclusive claims were made on the identical issue on seperate occaisions (type, consistency and duration of preflight testing for example).

This did not result from a lack of questions. The questions were fair, simple, direct, and detailed.

If this was an experiment, I am afraid the results support no conclusions, in fact resulted in little data on the eggenfellner aircraft engine package.

The data do however support the conclusion that if one is to host a "technical forum", the person answering the questions should be willing to engage in the discussion.

If one side views it as a technical dialogue, and the other expects a free marketing outlet with little willingness to answer the questions posed, well both sides will walk away feeling frustrated.

I guess we really should simply "rest assured"....that this was never to be a hard core technical exchange.

 

[rv6ejguy]

I think you will find in many industries including the automotive one that information is often not freely shared to whoever might ask for it. Certain data is sensitive, gathered at great expense and could be of use to competitors.

Often the information is only released after the model year debuts or even years after when it comes to testing, validation and R&D topics. Unless you have connections to the engineers in charge of these projects, information can be hard to obtain. GM Powertrain has been forthcoming after product release in some instances and sometimes SAE papers are available on certain topics from other companies.

I don't find it odd that Jan does not want to share certain info publicly. Jan is not a mechanical engineer and clearly employs evolutionary learning to improve the designs- a valid route used by all engineering teams. If some are disappointed that massive amounts of number crunching and analysis was not done, then welcome to the realities of business and experimental aviation products. You may be surprised in who develops avionics for our market and how these devices are debugged and tested also. You simply cannot do NASA type engineering here and expect to price products within reality for this market.

Bottom line, the majority of Jan's stuff works remarkably well especially considering the R&D budget and timetables involved compared to some of the established players in this field. Nobody produces perfection as we have repeatedly seen from some long established companies with much larger staffs and budgets.

I think Jan has answered most of the questions asked and that people have more of an insight to his products. My hat is off to Jan, giving builders another choice in powerplant and working to make the packages better each year.

 

[mcencula]

Not so useful

In my opinion, the difficulty experienced in this thread is related to two things:

1. Although Jan may feel he has comprehensive design analysis and test data, I suspect his idea of "comprehensive" is a small subset of what I and others would expect from a package that life and limb will depend on.
2. Regardless of whatever data he actually does have, he's not willing to share it.

Nebulous responses to some questions and completely ignoring others is the basis of my first point.

The second point is puzzling to me. Reverse engineering of this system (indeed any mechanical system) is quite a trivial matter for anyone so inclined. Thus, it's not as though there are deeply hidden trade secrets involved here.

Regardless of all that...

I'd like to thank the folks that took their time to post questions and information in an attempt to educate others. Also, thanks to Doug Reeves for hosting the thread and the moderators for taking their time to follow a thread that may be of little personal interest to them.

Last, but not least, I'd like to thank Jan for taking his time to at least attempt to answer the questions posed to the best of his ability. I'm sure Jan is exceptionally busy and he's certainly under no obligation to participate.