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In Heavy Maintenance class with Eric Tucker as instructor


Anticept

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Because  of the Rotax tight fit of pistons and cylinders and other parts, a little to much heat and your engine is toast just saying. There are engines out there that are much

better than the rotax design, motorcycle engines for instance, small CCs and a lot more power, no leaks no carb problems for 10 15 years. Carbs get worked a 1000 times harder

than any carb on rotax with no issues. My 2 cents I do like rotax engines but if  I had a choice it would be something better than this design. We are in the year 2014 we should

not be having issues with rotax engines, no leaks, no failures what so ever., I have been riding motorcycles for over 50 years never once had a problem with any of them. Tires and battery, change oil and filter that's it. These were Jap bikes no harleys, no triumphs, no nortons, no american made nothing. Kawasaki is coming out with 1000 cc bike

called H2R 300 hundred horsepower supercharged now that's an airplane engine, I wish.

http://www.motorcycle.com/manufacturer/kawasaki/intermot-2014-kawasaki-ninja-h2.html

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Figured I would mention, we're working on a junked 912 ULS engine as part of class. The engine ran for three hours without coolant, through several takeoffs and landings. Absolutely hosed; the heads and barrels are warped (removing the piston pins and rocker arm pins is a PITA), but it would not give up. It was shut down, and taken back out the next day and failed to reach rated power, so the pilot aborted the flight.

 

The coolant bottle was a flawed design on this aircraft (FD uses the rotax design, so breathe easy). The hose would go in through the top and only stick in a couple inches. Coolant would enter the bottle, but it would not suck back out as the engine cooled back down. Eventually the coolant was so low that it started boiling off until it stopped working. The pilot was registering high CHT readings, but chose to ignore them thinking it was a malfunction. The radiator ballooned and almost burst, and the CHTs melted out of the head (oh look, it isn't hot anymore, the CHT problem fixed itself!).

 

Procharger: aircraft use has some of the most abusive conditions for an engine possible. Unlike cars, motorcycles, or racecars, aircraft engines are expected to run at full rated power for several minutes, then run at 75-90% power for hours and hours. On top of that, regulations require that they continue to run for at least half an hour with the loss of a cylinder or fluids (except fuel and oil). Comparing them to motorcycles etc is not fair. Imagine running a cycle for an hour at 90% of rated power. If it isn't a derated engine, it would catch on fire!

 

Except for maybe freight train and cargo ship diesels, no engine is expected to run for the length of time at high power like an aircraft engine, and expected to continue running after the loss of a cylinder or critical system.

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Hamburger I disagree with your summation about motorcycle engines show me 200 hundred horsepower with rotax engine with the same cc and a motorcycle engine with the same cc can't do it ,

power these engines produce is twice what any rotax could dream of . Just because is has tight tolerances.doesn't make it sophisticated just saying. Thanks for your comment.

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Hamburger I disagree with your summation about motorcycle engines show me 200 hundred horsepower with rotax engine with the same cc and a motorcycle engine with the same cc can't do it ,

power these engines produce is twice what any rotax could dream of . Just because is has tight tolerances.doesn't make it sophisticated just saying. Thanks for your comment.

Procharger, I would like to insert a thought on this. I cannot argue either way without a better definition of "sophisticated", but to make a point, F1 uses what could be argued to be extremely sophisticated engines with high horsepower, but they do not last long at all. It is all a balancing act of cost, longevity, and desired performance. When you have an engine that demands such performance, consistently throughout various power settings especially towards the upper power band, AND to last a long time, you have to sacrifice some of the potential hosepower and a lot of economics to make it work.

 

Also, don't forget weight!!!

 

Edit: that bike you linked above has 16 valves for four cylinders. Try making a 16 valve aircraft engine while still making it a narrow profile, and keep the weight low. Then meet the safety requirements if a system fails. May very well be possible, but it is going to cost an absolute fortune!!!

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Anticept, you ever watched a motorcycle roadrace, bikes run for hours at 12 to 16000 rpm I am talking about design of engines look at what these engines produce in horsepower

I would say CC for CC they are way ahead of any rotax design, I am sure they are as sophisticated as any engine produced, almost anywhere in the world. Honda had a road race

bike back in the 70's it  had oval pistons and turned over 24000 RPM now that is sophisticated as Hamburger put it . I believe you could take that high horsepower engine

that can turn 12000 rpm take it down to 6000 rpm it would run as long as any other engine  and thats half power. I jus t measured My Kaw ZX14R which makes over 200

horsepower, the engine is only 16 inches wide take away transmission and its smaller than a rotax. Just saying, put duel spark plugs in it I would trust it to go anywhere. It

has 16 valves and 4 cylinders.

 

Not taking about 2 strokes all 4 strokes. Don't want 2 stroke airplane engine or motorcycle engine, rebuilt enough of  those already.

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Anticept, you ever watched a motorcycle roadrace, bikes run for hours at 12 to 16000 rpm I am talking about design of engines look at what these engines produce in horsepower

I would say CC for CC they are way ahead of any rotax design, I am sure they are as sophisticated as any engine produced, almost anywhere in the world. Honda had a road race

bike back in the 70's it had oval pistons and turned over 24000 RPM now that is sophisticated as Hamburger put it .

Two strokes though, right? Two strokes generate enormous horsepower because they have twice as many ignition events, and simpler construction means you can run at much higher RPM without encountering the same problems as a four stroke.

 

What is the rated horsepower of those motorcycles, and how close are they running to it? RPM is not an indicator of horsepower output. I can make a rotax engine redline and fly apart by taking off the prop, and it wouldn't need hardly any horsepower to do so.

 

Edit: I don't consider a rotax to be more sophisticated, because the technology and current engine designs was designed in the early 80s, and modified over the years. That said, aircraft engines do tend to stick with proven designs for long periods before automotive tech carries over.

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That's my point same engine since 80's should have all the problems fixed by now, wouldn't you agree. Ham you said in earlier post that

The Rotax engines are motorcycle and snow mobile engines  are they on the ground, that is your quote just saying. Aint this fun?? So finale

? is my airplane engine a motorcycle or snowmobile engine??

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That's my point same engine since 80's should have all the problems fixed by now, wouldn't you agree.

If you want to pay R&D :).

 

Also, you are still comparing apples to oranges. You really need to get into engineering for aircraft engines, it's a whole other ballgame. If aircraft engines had the R&D funds that big name automotive manufacturers have, you would have an even better engine. But, I seriously doubt you will get them as powerful as ground vehicles though due to weight to cost (think exotic alloys) issues.

 

As a side note, aircraft engines have a much bigger problem with resonance than any other method of transportation, because water and wheels transmits it to the ground. With aircraft, it just bounces around until it dissipates into the air.

 

Also, it's funny how you talk about those motorcycles with the stupidly high horsepower. As said, american vs european thinking :P

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What can I say I like horsepower  I am an American. I need to get into engineering what's so hard about making an engine last a long time with good power. Those crude

Cont. and Lyco. engines are junk compared to what can be produced today, Yes I know its all about sales and money give me a break? Gas drinking low power heavy engines

no thank you, as I said I like my Rotax but there could be something better. Only reason we don't have something better because the people that could make it happen

know its not worth the time or effort, airplanes and pilots are a dying breed I am sorry to say. Gov't regs and insurance ruin it for all of us. Nobody wants the liability. Oh

yea lets not forget lawyers. :wacko:

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Hi Corey,

 

I keep telling people to go to school and ask questions.

I have gone to many Rotax schools in country and out and it's the only way to obtain knowledge.

 

 

All I have to say is there is a God!

 

 

Jim,

 

There are more than one reason we don't get all the info we sometimes crave. It may not be the same reason for each item.

There are definetly issues with some writings, some translations and some things Rotax just won't share at our level. Then when they do let info out you'll have the right wing and left wing groups of each side and then things get lost as info passes down and rumors run rampant. Some things are just Rotax protected MFG info and the Euorpean culture and mind set is different from ours.

I'm just a little guy too so I'm not privy to a lot of it. I get what I can from the highest levels I can and try when able to let people know. Sometimes I'm sworn under the threat of death to keep some things to myself.

 

I certainly don't have all the answers and can't control anyone above me. I just try to work in the system as it is the best I can. I have just been lucky enough to have a friend or two at some fairly high levels with 30 plus years experience.

 

I wish I knwe more and it has taken many years to get this far.

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I need to get into engineering what's so hard about making an engine last a long time with good power.

What about weight and cost? Anyone can make a long lasting engine with good power, but how much is it going to cost, and how large will it be? Just making it so it is long lasting with good power are basically engines for power stations and cargo freighters.

 

We're talking about billions and billions of dollars of research that has gone into engines for the past nundred years, with a lot of flops. The number of successful engines that meets the demand of power, economy, and weight is a tiny fraction. I welcome new tech, but it isn't something that a person will wake up to one morning and designed an engine from the ground up. You also need to design the manufacturing and support process.

 

Most newer aircraft engine designs are riddled with problems. Theilert, jabiru, rotax, etc. we just try to negate issues as much as possible. One of the reasons lycoming and continentals haven't changed much is because they WORK. As a downside, they are simple, inefficient, and heavy.

 

Automotive engines are no different, they too all have their share of problems.

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Corey, this has been a very interesting discussion. I hope you continue it.

 

Others - let's forget the diversion on motorcycles and so forth and concentrate on what Corey is able to bring from the course. Let's talk about how good other engines are in a different thread, which I'll be happy to follow.

 

Roger, the more I read here about Rotax, the less happy I am with it. The idea that the pilot is an idiot is unacceptable to me. I was used to flying my T210 LOP with very happy results and that takes good instrumentation, good operations knowledge and good pilot skills. I'm going to keep my eyes open for engines that let me be in charge instead of being along for the ride.

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Corey, this has been a very interesting discussion. I hope you continue it.Others - let's forget the diversion on motorcycles and so forth and concentrate on what Corey is able to bring from the course. Let's talk about how good other engines are in a different thread, which I'll be happy to follow.Roger, the more I read here about Rotax, the less happy I am with it. The idea that the pilot is an idiot is unacceptable to me. I was used to flying my T210 LOP with very happy results and that takes good instrumentation, good operations knowledge and good pilot skills. I'm going to keep my eyes open for engines that let me be in charge instead of being along for the ride.

Keep in mind, this was also designed in the 80's, then they did some tweaks to make the 100hp engine. Even then, rotax went the route of automation.

 

The thing is, in today's age, automation woos young people. They want to be lazy. The more you let them be lazy, the more money they will throw at you. Not trusting the pilots, and only kindof trusting the mechanics is only one part of it.

 

Legal ramifications is probably the biggest, though. Seriously, there's a reason rotax won't give out the overhaul manual. I was told you cannot even get it in electronic format, they will only ship you a binder. Somebody who is not trained or equipped would get into the manual, cobble an engine together, and get hurt and sue Rotax. Even if an accident happens, the name on the engine doesn't magically change.

 

I myself am very put off by today's legal system too. I don't do work for the public because, quite frankly, pilots are assholes. Well, a few are anyways. Still, parts are expensive, and I need to make a living. Yet no matter how much I try to cut a break, to a few people, I'm the bad guy because the bill is high. I wouldn't put it past those kinds of people to point the finger at me if they screw up and get hurt, and it only takes one lawsuit to ruin me because of how little I make, even if I win the suit. Think Daniel Bernath and the little company called flight design. It cost FDUSA a lot of money to defend themselves. Now think about how many Rotax engines are out there... That's the drawback of a litigious society, nobody wants to tell you anything for fear of implication or litigation and insurance costs are very high.

 

On another note, the predator uses the 914. A while ago the military would sell the engines after 1000 hrs. People would buy crates of them, salvage parts, then sell the complete engine. People were buying them and getting hurt, and the finger got pointed at rotax. The military started a scrap order a few years ago though, to rotax's relief (engine parts are destroyed and sold for scrap metal instead of sold as is).

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Roger, some companies are more open than others and I as a consumer make choices. The attitude of Rotax as Corey is passing along is not consumer friendly.

 

One of the dangers of the "secret society" is that the "secret society" can make up anything it wants and the rest of us are stuck with whatever the priesthood preaches. I simply won't live like that.

 

OK, off my soap box, but I'll not change my attitude toward wanting to see documented references for whatever is cited as the way we should be maintaining or operating the engine. We have seen an example in VAF of where Dean Vogel and you may have differing interpretations about some Rotax issues. That is the very disagreement that is unsettling to the consumer.

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Posted Yesterday, 10:06 PM

Roger, some companies are more open than others and I as a consumer make choices. The attitude of Rotax as Corey is passing along is not consumer friendly.

 

 

Hi Jim,

 

I fully agree, but it's a different mind set overseas at times. I just learned to work in and with the system a long time ago.

I watched complainers get dealt out of the communication groups and the people that worked and accepted the system as is got more inside and timely info. It also helped get things done much faster.

 

We will never be able to change the system, but we can benefit from learning how to navigate within the system.

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Hi Corey -- could you ask Eric about the Advance Ignition Module shortage in the US?  The 3 US retailers have been out of stock since mid-July and are still potentially 4-6 weeks away from meaningful restocking.  CPS might be receiving some this week (with me being #1 on the list).  I'm aware of approximately ~10 owners of 06/07 models grounded due to lack of parts.

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If that's true, then you do not really have full power - a partially closed slide is equivalent to just throttling back with a conventional carb. That would have to leave a lot of performance on the table.

 

The performance chart is based on WOT.  If WOT is not achievable above a certain DA then the charts are not correct above that altitude.

 

I have more hours with a mixture control than without.  I wonder if Rotax thinks I'm dumb or are they just taking the easy way out and not providing tuning at altitude?

 

Corey,

 

In your follow up will you confirm that the iS leans when not below 92% throttle, or when not in econo mode?  The Rotax language sounds to me as though leaning only happens in econo mode.

 

I would love to start up a Rotax 912ULS that has been tuned to provide WOT and leaning adjustment. I then could see how different or similar it is to a Lycoming just by slowly leaning and seeing if RPM increase and if so, how much.

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There is no mechanism linking the throttle to the jet. It is purely driven by differential pressure. We're done for the day, so I will ask tomorrow.

 

Ok, but once you have arrived at a high enough throttle setting and the needle jet is full open there is no mechanism to lean the main jet.  The main jet takes full control of the mixture and its only setting is full rich.

 

How can we determine what is happening?  When I'm at 10,000' cruising WOT how can I tell if my needle jet still has mixture control and that WOT isn't wide open?

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The performance chart is based on WOT. If WOT is not achievable above a certain DA then the charts are not correct above that altitude.

I guess it depends on what WOT represents.

 

In a standard carb, or even fuel injected motor, it would clearly be when the throttle plate was fully open, providing absolute minimum airflow restriction to provide maximal airflow and, hence, the potential for maximum power.

 

But in our "constant depression" carbs, I think we're being told that even with the throttle plate fully open, above a certain altitude the diaphragm might not have enough "oomph" to lift the slide all the way - and it's the slide that is the "real" throttle plate on our carbs.

 

So, at WOT we may not really have WOT, which makes the terminology confusing.

 

That's if, of course, what we're being told is, in fact, the case.

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Confirming that the 912iS does NOT remain at full rich if it is not needed. It enrichens above 92%, but the engine would have trouble running at high altitude at full power if it did not lean out some. Once you go below 92%, it further reduces mixture to save fuel, as the detonation risk drops.

 

Also, Rotax would be using O2 sensors and doing live tuning if it weren't for the possibility of using lead fuel. The lead destroys the O2 sensors.

 

We will be going over the last of carbs shortly, I will ask about the VV and the advantages and disadvantages, including the question about if it acts like a reduced throttle.

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