Rotary Simplity Equals Reliability?

[Crazycanuck]

I have been thinking about which type of engine to put in my Cozy eventually. Rotary engines are on my short list of choices that I am considering. I just wanted to comment though on the common argument that rotary engines are more reliable because they only have 3 moving parts. At first I felt that this was a good argument, but not so much anymore. The same could be said for 2 stroke engines, as they have only three moving parts at their core (piston, connecting rod, and crank), but they tend not to be nearly as reliable as 4 stroke engines generally speaking. I have a very complex engine in my motorcycle with things like variable valves (VTEC) and its engine is considered one of the more reliable engines out there. So in the end it isn't really the number of parts that determines reliability, rather how carefully those parts were designed for their given purpose.

 

my $0.02

[TMann]

John Slade had his turbo charger blow sending pieces of compressor blades into the combustion chamber ........... and flew it back to the airport.

 

I wonder if a piston engine could have done that?

 

(as a matter of fact ..... I just ordered part #EM-LERX-20B from CG Products!)

[Crazycanuck]

Fair enough. Please recognize that I am not suggesting that rotary engines are not a good choice or good design. I am merely saying that a simpler design in and of itself is not a good indicator of reliablity.

[TMann]

With the rotary, it's more than the number of moving parts but also the direction of movement and vibration it results in.

 

Another factor is the cost of rebuilding as well as the life expectancy of the engine.

If I remember correctly, the above example resulted in a repair bill of between 500-800 bucks.

[Edge 513]

Dear Canuck,

At the risk of starting another firefight, I will just post a couple of pics of one of the most skilled and careful [and beautiful] installations of a Rotary known to man. This is Buly's 13B that he has taken out of his Cozy, and it now resides next to his hanger workbench on a pallet. He gave up on it.

Check out Buly's work in these pics. [Not cutting corners he had the Chris rotary-racing guy build it to TracyCooks recommendations even]. If the careful attention of this guy and all his extensive research and follow up with the Rotary Guru's didn't help him create this work of art and allow him to keep it flying without spending hours on the ground after most every flight...I don't know what would. He started with a turbo- then de-turboed it and still didn't feel comfortable.

He is currently putting a cylinder driven engine in its place.

Theres a few bright folks here that want to use the rotary,and thats what it's going to take....is bright folks. I'm a bit dimmer, so I am going to be a "Cylinder-man". These are Bulys experiences not mine, he and I were just emailing last week and he sent the Dr Buly photo to me talking about his new engine install.

I only offer this, to show that there appears to be a lot of figuring and work to a Rotary. It isn't a just simple plug-n-play option.

[Cozy Girrrl]

You exchange relative simplicity of engine components for the risk of subsystems; cooling, fuel delivery, ignition control, reduction drive and everything is new and unique from build to build so no standard proven recipe.

All that and the nay-sayers are like the plague.

I am not trying to detract from the RX but just trying to point out what the state of the art is.

Hopefully with greater numbers the knowledge base will grow and more standards for installations will be adopted.

We've been to the rotary fly in and were very impressed.

Regards, Chrissi & Randi

[dirtdox]

You exchange relative simplicity of engine components for the risk of subsystems; cooling, fuel delivery, ignition control, reduction drive and everything is new and unique from build to build so no standard proven recipe.

 

I agree. I have had several Rx7's(still do). I like the smoothness of the engine and, at its core, it is simple. The accessaries to make it suitable for aviation are not so simple.

[velocity dreamer]

One thing that most people need to consider when choosing an engine would be the availability of avgas over the next several years. With the lead issue and the cost of manufacuring is going to put avgas prices on the rise. Fewer refineries are making avgas and the trend on fuel is to impove diesel. When I build, I plan on buying an engine that is either for 93 octane or diesel. I work at an FBO and order the fuel. I see the decline in availablity and fuel rise with no signs of comming down.

thats my thoughts.

 

Lynn

[Crazycanuck]

In my research on rotary engines so far has led me to a few RX 8 forums. Generally I have found that those guys seem to have alot of blown engines. It is not a scientific sampling and many of them guys were doing significant modifications, but they they certainly weren't trouble free engines.

 

It is great to see people trying to make it work. The experimental category is intended to support innovation, and that is exactly what is happening. That is what makes a person an aviator instead of just a pilot. However, so far it seems that rotaries are more suitable for racing applications.

 

Has anybody considered a Briggs and Stratton engine? JK

[Cozy Girrrl]

Actually rotaries are more suitable for generators, good high output, running at higher RPMs. Would be good for offshore boat racing and aircraft when the support bits are worked out.

Offshore racing is the downfall of piston engines. Constant high output at high RPMs with frequent unloading and overspeeds.

...Chrissi

[emteeoh]

I don't know that what they do in an RX-8 is a good indicator. People modding RX-8s are, I would think, likely racing. Racing is a good way to blow out any engine.

[argoldman]

In my research on rotary engines so far has led me to a few RX 8 forums. Generally I have found that those guys seem to have alot of blown engines. It is not a scientific sampling and many of them guys were doing significant modifications, but they they certainly weren't trouble free engines.

 

It is great to see people trying to make it work. The experimental category is intended to support innovation, and that is exactly what is happening. That is what makes a person an aviator instead of just a pilot. However, so far it seems that rotaries are more suitable for racing applications.

 

Has anybody considered a Briggs and Stratton engine? JK

So I am listening (reading) to this string with thoughts hummmmmming in my mind, occasionally wanting to boing boing boing my head.

 

What I seem to hear is concepts of failures of rotaries told by people that heard about it through someone else who might really have known the facts surrounding the situation. (the same goes for piston engines)

 

The fact that Renesis boys seem to be "blowing" their engines with regularity means nothing unless you really know what the nature of the Blowing is. Is there an attempt to super-turbo charge inappropriately, or is the design of the engine bad for our applications.

 

The fact that incredible work can be done to install an engine which later is removed to accomodate another type means nothing until the reasons, be it failure, inability to get it to run properly, and all of the facts are known, not assumed.

 

I remember spending 9 months trying to fuel inject my Norton engine, using an incompatable type of fuel injection. Ultimately EFI solved that problem. The reason that the prior attempt failed was not the engine, but it was the nut behind the wrench that didn't have the proper knowledge.

 

There is no embarrassment if one cans one concept for another, however for anybody to draw conclusions about the validity of a concept secondary to hearing that someone did, indeed, change, without specific knowledge about all of the facts is folly. If we base our decisions on that kind of knowledge, then none of us would ever consider a lycoming/continental-- Crankshaft/camshaft/cylinder/oil pump/cooling etc etc problems also exist in them.

 

If you are interested in Rotaries, get Tracy Crooks Bookoid which chronicles his efforts, both successes and especially his failures as he led up to what he now flies and sells. John Slade also talks freely about his failures and his road to the success that he has now

 

For those of you who have changed back, enlighten the rest of us what kind of problems that you had. Help us move forward or discard the concept.

 

You learn very little through your successes. Evaluation of failures enables great strides forward.

 

I'm still on the fence, however leaning one way.

[tonyslongez]

I thought it was interesting to show Buly's install. Sure Buly had problems with his beautiful install, just because you can install something pretty doesn't mean you can make it run. Interestingly enough Tracy's installs are not pretty at all and yet he flies the hell out of his airplane. I really want the rotary to work. I would love to put one on the Berkut. I'm just scared to death, do you install a LYC and go fly or go rotary and spend 9 more months after the build to get it running. I'm not sure if it's there yet.

 

Tony

[Edge 513]

Tony- my point about the craftmanship is - it is obvious the guy was wanting to do the best possible job. If you see a crappy job- you typically think "well the guy maybe missed something- he wasn't careful". Thats all. Theres plenty of shadetree mechanics that can "make 'sheet' dance", as the oldboy saying in the South goes. Buly tried everything he could before resigning himself to the last decision.

 

Rich- I'm afraid Buly won't post to any forum anymore. But you are right..ASK HIM for HIS experience. Changing out an engine for a different one "means nothing" is kind of a odd way to put scrapping hundreds of hours of research and installation time...and doing it all over again. This isn't a minor injector system or alternator he finally decided to change out. If you can look at what he did and discredit it as a hoe-hum installation and sidestep the fact that Tracy Cook WAS involved, there is no elephant in your living room. If you decide to go with the rotary, just know that you need to be more thorough and spend more money [don't ask that figure- if you are on a budget] than Buly did. 2 years ago I sat on the engine fence, watched John Slade and then Buly and the teething problems. Well, I KNOW MY limits...I personally don't want to tinker for years and end up with paying for an engine twice. But thats just me. I know MY own limitations. I certainly wish those choosing a rotary for a pusher install the best of luck. Theres a few guys who yanked out there wankles out there...ask them why and what became of it? Maybe they missed something. If no one tries to forward the wankle, they won't figure it out as Chrissy says.

Oh BTW, Chrissy, I do have a few small age spots starting to show up...at least I thought they were age spots. Are you telling me that its really the plague?=

[tonyslongez]

Tony- my point about the craftmanship is - it is obvious the guy was wanting to do the best possible job. If you see a crappy job- you typically think "well the guy maybe missed something- he wasn't careful". Thats all. Theres plenty of shadetree mechanics that can "make 'sheet' dance", as the oldboy saying in the South goes. Buly tried everything he could before resigning himself to the last decision.

I agree with you 100%. A nice install is a nice install. I think he was close to figuring out what the gremlin was that was causing him so much grief. You can certainly have those types of problems in any install right? I didn't agree with his decission to yank his install. Look how far he went. He did miss something. I believe he had a wiring problem somewhere if I remember. Like you said

I KNOW MY limits..

maybe Buly didn't know his! maybe wiring isn't his cup of tea. I hope when I'm ready for my engine the rotary will have evolved a little more. If not, a lycoming it is. For me anyway.

 

 

Tony

[Edge 513]

BTW Tony- your game is ON with your Berkut..really great to see you skillfully correcting that airframe!

REALLY good stuff.

[TMann]

I really hate to see people point to Buly's install as a failure. Buly had it flying and to my knowledge, the engine's performance was not a problem. The point of his frustration revolved around electronic interference that hampered his radio communications.

That's all I've read on the matter and I hope his change to a Lycoming solves his problems. I would hate to think he would pull his power plant only to have the same problem with a different engine.

 

Engine performance is pretty simple. Compression, fuel, oxygen, spark and longivity. As builders, we can screw up lots of aspects to any engine install but that doesn;t mean the fault lies with engine.

 

Study, study, study!

[Lynn Erickson]

I agree with you 100%. A nice install is a nice install. I think he was close to figuring out what the gremlin was that was causing him so much grief. You can certainly have those types of problems in any install right? I didn't agree with his decission to yank his install. Look how far he went. He did miss something. I believe he had a wiring problem somewhere if I remember. Like you said maybe Buly didn't know his! maybe wiring isn't his cup of tea. I hope when I'm ready for my engine the rotary will have evolved a little more. If not, a lycoming it is. For me anyway.

 

 

Tony

A guy with his talent does not yank an engine because it maybe causing a radio problem. that is to easy to fix. you yank a radio or an engine because you can no longer trust that it will keep working. you then install a radio or an engine that you can trust.

[tonyslongez]

Edge

 

Thank you. It's nice to be recognized by my peers.

 

Big-T

 

I certainly don't think Buly failed. I think he's been instrumental in his install. It's nice to see what can be done with these engines. I think the people we REALLY and I mean REALLY!!! need to be talking to are INDY guys. Indy teams have alot of things worked out that involve 200mph. Dave Algie comes to mind. Dave has a wonderful shop and his fabrication skills are the best on the planet. If the rotory engine is going to be a viable power plant that guy is the one we need to get on board with us. When the time comes. I would love to give him some money to make a standard pusher install for the rotory.

 

Tony

[TMann]

A guy with his talent does not yank an engine because it maybe causing a radio problem. that is to easy to fix. you yank a radio or an engine because you can no longer trust that it will keep working. you then install a radio or an engine that you can trust.

How 'bout we let Buly tell his own story?

I hope the new engine solves his problems.

[CBarber]

Gotta chime in here. IIRC the issue that was driving Bully nuts for quite a while and documented pretty well on the rotary aviation forums, most notably I believe "Fly Rotary" was a wiring issue where he RE-WIRED his Program Control Module (PCM) from its factory (Tracy's factory) to make it fit just where the canopy closes. Then he kept having wiring issues that were affecting his engine runs. After what seemed like months of frustration he decided to change to a lyc....again, IIRC, he then discovered the problem was that where he placed the re-wired PCM was being interferrd with by the opening an closing of the canopy, thus an inconsistant problem.

 

So, as it turned out, not only did he re-wire the unit, he placed it in a physical location that was having a separate and independant action on that part causing the dreaded "intermentant failure" I don't really see how the rotary is to blame here as the same issue could have happened with any engine type.

 

Now, that being said I do not discount the other frustrations he may have had with the install that may have led to the final wire issue being the last straw. A real pity. I remember how heart sunk I felt when I learned of his decission.

 

Finally, in the desire for full disclosure (lawyer thing), I am currently working on my rotary install and am having some definate teething pains. I just got my ECU and EM back from Tracy and I can't seem to get the damn thing to run.....seems to almost want to start, but just won't quite do so...or it will start for a minute, die and then not restart. AAAAAAGGGGH. To be fair though I have only had the unit back a few days and due to the "dating thing" have not had too much dedicated time to check some basic stuff like to verify the timing, check the plugs (the sparks are sparking and the injectors are chirping away while in test mode though....so sparkd and fuel and air are all check) etc.

 

But, ya know, it is still moslty fun, even if I would kill to get past this current (and longest lived) frustration.

 

If I had a load of money fall out of the sky I am not sure what I would do.....Lyc or some real serious considerationm to the Mistral. I really like the rotary concept and now have some serious cash (over a few years) "invested?????" in the project. FWIW.

 

All the best,

 

Chris Barber

[argoldman]

 

Rich- I'm afraid Buly won't post to any forum anymore. But you are right..ASK HIM for HIS experience. Changing out an engine for a different one "means nothing" is kind of a odd way to put scrapping hundreds of hours of research and installation time..

 

I stand, or sit misunderstood. I did not mean in any way to imply that Bullies changeing to a piston engine etc etc meant nothing to HIM. I certainly can understand and empathize with him.

 

What I was referring to, and only to was what WE can or should draw from his decision without knowing why. The fact that he worked with tracy means little unless we know to what extent and to what extent he modified tracy's suggestions-- after all Tracy has and many others have had many hours of successful running.

 

Bullies work did look incredible. We do not know what kind of problems he was having were they with the rotary, gear box, EFI or ignition and what kind of modifications that he made.

 

I give Buly credit for switching, I just can't draw any conclusions from the switch. I too wish him best of luck and flying with his Lycoming

[Eccentric]

Approaching 9 years and 700 hours on my rotary. Kein Probleme. Wouldn't fly anything else.

http://www.ductedfan.com

[Edge 513]

Well howdy eccentric! Like the 1st Austin Power movie.."there you are..."!! You have to be the moment of inspiration here- since you have a pusher install. Do you have any similar powered buddies out there in canards? Are you turboed or not? Pictures pictures pictures please. Theres a lot of interest from several here. Too much to bait them with 3 short sentences and tip your hat!!

[Eccentric]

Well howdy eccentric! Like the 1st Austin Power movie.."there you are..."!! You have to be the moment of inspiration here- since you have a pusher install. Do you have any similar powered buddies out there in canards? Are you turboed or not? Pictures pictures pictures please. Theres a lot of interest from several here. Too much to bait them with 3 short sentences and tip your hat!!

There is more info at the website link I provided. You have to click some of the links on the page to get more pictures. Of most interest to builders would be the link "how to install a rotary in your long-ez".