Eggenfellner Engines - Technical Only

[janeggenfellner]

Can you share the inertia figures for the two wheels and the connecting spring rate?

We don't share everything. Some of the many hours of testing and development is kept in hose.

Jan

[DanH]

<<We don't share everything. Some of the many hours of testing and development is kept in hose.>>

Sure, I understand. How about just the spring rate then? Anyone can measure that in less than 10 minutes, and 5 of them would be used removing the upper cowling. Need a fish scale, a digital level, and a screwdriver <g>.

[Jconard]

How many test hours has the driver and flywheel system been exposed to and other what conditions?

I understand that the prior drives were tested for hundreds of hours using heavy metal props. What testing was done on the new G3?

I guess when you said it was a dual mass flywheel, I assumed it was the factory Subaru flywheel. Am I correct that it is actually made in house?

[Randy]

Leonard,
I don't think Jan is making any dual mass flywheels as they are readily available in the after market. If you do a search on them you will see several brands available. I think Jan has changed brands from the one in use on my STI engine.

I also am interested in learning about the testing process with the Gen 3 drives.

Randy C

[DanH]

Slow afternoon, so I spent a little time on the web looking for good information on dual mass flywheels. Most of what you'll pop up with a Google search is garbage. Here's the gold; a technical white paper from LuK:

http://159.51.238.62/remotemedien/me...techniques.pdf

Excellent illustrations, correct and incorrect applications, design methods, and simulation. The exploded DMF illustrations are worth the trip even if you find the rest unfathomable.

[Mike S]

Dan, just read the info you linked.

My head hurts.

[Geico266]

Dan / Jan, I need to understand where the dual flywheels are in this set up. I could only see one fly wheel on the engine and it is stock. Is the other one the prop?

[David-aviator]

Originally Posted by Geico266

Dan / Jan, I need to understand where the dual flywheels are in this set up. I could only see one fly wheel on the engine and it is stock. Is the other one the prop?

Larry,

Take a look at the pdf file Dan linked the thread to. There is a diagram of a dmf on page 13.

I had the thing installed at the EGG hangar in April of 2006 when we upgraded GEN 1 to GEN 2. It's pouring down rain here right now or I'd wander down to the hangar and check the log, but I'm guessing it has operated about 80 hours. So far it is working fine. It is a bit weird in that when a prop blade is moved, the engine does not follow it immediately. The springs are in compression and at some compressed value, the engine turns. I should have the engine back together in a week or so as GEN 3 is due back tomorrow after a seal change and other improvements. It would be sooner but we are leaving town for 5 days. I will measure the break out force as best I can and report what it is.

[DanH]

Ya'll will probably like this:

http://www.zf.com/multimedia/zmsFunk...nglisch_V3.wmv

[Randy]

Dan,
My head hurst just from looking at all the pictures of the Dual Mass Flywheels, but they really do make me curious about the design of the DMF on my STI engine.

I would think the spring rate would be important, but mine must be working OK. The reason I say this is even at a low idle speed I hear no rattle up front. In fact I hear very little rattle at shut down. At Jan's suggestion, I am keeping my idle speed high, at around 800 prop RPMs to take it easy on the gear box and the DMF, but I am unsure if this is needed. I find that 800 RPMs is just a bit too much for taxi on pavement and results in more brake dragging than I like.

I have about 15 hrs on my Gen 3 so far and it has been a good experience. The airplane feels stronger, (kind of hard to explain that but it does feel different, and better), and the new gear ratio does seem to help the STI get more in to it's power curve at lower and more efficient prop RPMs. In my case the ratio has had some domino effect in that I now need to get a larger supercharger driven pulley to slow it's speed down. The new gearbox drive ratio results in hitting supercharger redline (14,000 RPMs!) at about 2300 prop RPMs.

At first I thought that restricting my prop RPMs to 2300 would not be acceptable, and actually it isn't, but my experience has been that the airplane still performs very well. At 2300 prop, I am hitting 4,646 RPMs on the engine. This is above the peak torque speed of the engine so I can feel free to apply full boost at this engine speed. I will still proceed with changing the SC pulley to get those RPMs between 2300 on up to 2700 available to me but I can see that I won't be using this engine in that zone very often.

A note on my flying experience with the supercharger. There are many pros and cons between superchargers and turbo chargers and I have the general feeling that a good intallation of a turbo charger would have a few more advantages than the supercharger I have, but...

I have been finding it a real pleasure to use the supercharger, now that I have a seperate lever for controlling boost. I recently changed out a single push pull vernier throttle arrangement that would close the waste gate at the end of it's travel, to a two lever quadrant, one for throttle and one for the waste gate. I can cruise around at very economical fuel flows with the waste gate open and there is quite a range of power level available to me simply by pushing that lever foward.

Using the two lever system adds a little more pilot work load but I find having a seperate lever to operate the waste gate makes controlling the power output of the engine much more precise. With the waste gate open I see about 29" at lower altitudes and closing it brings the MAP right on up to a max. of 52" hg at my field elevation of 460'. 52" really makes her groan. My normal take off boost level has come down some (maybe around 40") with the new two lever control.

Anyway my point here is that I still think a turbo charger would be a better method of boosting this engine but my flying experience is telling me that what I have is really working pretty well.

Sorry to swerve off into another subject, perhaps better to have added a seperate post...

Randy C