rotary question

[tdale4]

I'm ordering my plans for the cozy mk iv next payday :-) I plan on using a mazda rotary to power my bird, for many different reasons. I know cooling can be a problem in some installations, and I live in Texas. Has anyone come up with a good cooling system for this specific engine and plane? I think i remember seeing a guy who installed radiators in the wings or strake area. Has anyone tried this? To combat the noise I plan on using a turbo with minimal boost 4-6 psi. What I was thinking is a norimalization trubo like the eggenfeller subaru. Anyone know if this is difficult to do? I know it will me many moons before i need to worry about an engine install but I want to plan it out in the begining.

 

Thanks,

Tim

[ekisbey]

Talk to John Slade, and read his website. He's perhaps the only "authority" so far on Rotary installations for the MkIV, since he's closest to flying, and certainly the strongest proponent.

 

I, too, am strongly considering the Mazda installation, and have been paying very close attention to his progress. Don't make the mistake, however, of letting your engine decision delay the start of the building process. It's going take a year or two of real progress on your airframe, at the soonest, before you need to seriously consider your power options. Something can easily change by then, and there will be much more information available on the success of the Mazda in a Cozy IV.

[John Slade]

Thanks for the "perhaps". It's appropriate. There are a lot of people installing rotaries in Cozys and many people wider than me putting them in RVs. Mine is probably the nearest Cozy IV to completion with Paul conner, Steve Brooks and Bulent Alieve close behind. A lot of what I'm doing has already been done in pushers by Greg Richter (Cozy III 13B turbo), George Graham (custom LongEx), Perry Mick (ducted fan custom long EZ), Brice ? (3 rotor turbo cozy IV) and a few others I cant think of right now.

 

Reading my web site ( http://kgarden.com/cozy/chap23 ) will provide lots of detail, but here's a quick summary:

 

I have a 6psi pop-off valve (a radiator cap) installed on the 65mm throttle body to keep the boost down, at least to begin with. I also have a manual wastegate push-pull cable.

 

The cooling is definately an issue and I'm going a bit off on my own in this area. Greg and George have large scoops. I have a large rad under the engine and two stock 3rd gen oil coolers. I'm (currently) using just the plans NACA scoop for intake air, with a plenum to feed the heat exchangers. I also have a large cooling fan in there, plus an exhaust aumentation setup around and behind the turbo.

 

I agree that the best thing to do is watch and wait.

 

As far as the work involved, it's no picnic, it presents a few challenges and it takes time, but I'm hoping the results are worth it. Time will tell.

 

Yes - expect me at Rough River.

[John Slade]

Oops. I said wider (which is true), but I meant wiser.

[Dolan]

I'm a newbie regarding these magnificient cozy airplanes, even though I've been lurking for a couple months, learning from you guy's generous & informative messaging. First Issue: I'm seriously considering buying a Cozy Classic project mostly finished which is already equipped with a 1985 Mazda Rotary. Nat Puffer was quoted as believing the Rotary would depreciate the value of the plane. Is this your collective experience, or just his private (now public) opinion?

Thanks...........there'll be many more questions, I already know Dolan

[David Staten]

I'm ordering my plans for the cozy mk iv next payday :-) I plan on using a mazda rotary to power my bird, for many different reasons. I know cooling can be a problem in some installations, and I live in Texas. Has anyone come up with a good cooling system for this specific engine and plane? I think i remember seeing a guy who installed radiators in the wings or strake area. Has anyone tried this? To combat the noise I plan on using a turbo with minimal boost 4-6 psi. What I was thinking is a norimalization trubo like the eggenfeller subaru. Anyone know if this is difficult to do? I know it will me many moons before i need to worry about an engine install but I want to plan it out in the begining.

 

Thanks,

Tim

You need to make an effort to get to the Mid-Winter Rotary fest being hosted by Bill Eslick in GRANBURY TEXAS, right down the road from you. Feb 10-12.

 

http://www.weslick.com/rotorfest.htm

 

You will get to see many many rotaries in person, up close, and talk with the builders.

 

Dave

Houston

[David Staten]

I'm a newbie regarding these magnificient cozy airplanes, even though I've been lurking for a couple months, learning from you guy's generous & informative messaging. First Issue: I'm seriously considering buying a Cozy Classic project mostly finished which is already equipped with a 1985 Mazda Rotary. Nat Puffer was quoted as believing the Rotary would depreciate the value of the plane. Is this your collective experience, or just his private (now public) opinion?

Thanks...........there'll be many more questions, I already know Dolan

Value is in the eyes of the beholder. Nat is right.. and wrong too.

 

Resale value is practically meaningless if you never plan to sell the plane. The word on the street is that auto-conversions of any flavor tend to have less resale value than certified engines because of the "unknown" factor. This "unknown" factor is a bigger player in true custom engine installs (such as the rotary, since there are few firewall forward options out there, if any, anymore) as compared to packaged auto conversions.

 

To me, if it works as it should, the rotary will perform just as well or BETTER than the certified engine it replaces, for much less initial and continuing maintenance cost. Considering a new engine IO-360 with composite adjustable prop would run over $30,000 new, and I am able to get same if not better performance with less than $7,000 outlay, I wouldnt be offended if the resale value was $15-20,000 less than someone who had an identical plane with a certified package.

 

Im sure if someone had a factory Mistral package installed at its $30,000 outlay it would likely keep its value in a resale scenario.

 

But.. again..those of us building our own dont plan on parting with it anytime soon, and those who have, I have noticed, sometimes offer the airframe for sale separate from the rotary engine, selling the airframe to whomever wants it, and the rotary to others in the rotary community. Best of both worlds.

 

Dave

[Nathan Gifford]

It may affect the resale, but the better question is does it impact your return on investment. If you consider the cost of installation, maintenance, and fuel you may be paid less than a certified powerplant installation, but make up for it in the final sale.

 

The hidden cost of ownership in non-cert installations is that you do not have the same wealth of support certified engines have. The Internet has helped non-cert apps and probably the two best developed engine apps are Subie and Mazda. However, without standard installations (aka firewall aft) you are still largely on your own.

 

Be aware that every day that passes, good installations are getting many more hours on them. John Slade's Slick Kitten is starting to purr and has even flown outside of its 40 hour sandbox with both its master and mistress on its lease.

 

In short, keep your engine options open and remember you'll have over a year before you need start thinking of committing.

[Dolan]

Thanks, David & Nathan!

The rotary is 'engine of choice' for me because of the reasons you've mentioned. I really hoped my initial cost and operating costs would be substantial enough to ease a lot of any "pain" I might experience on a resale 'down the road' because of a price penalty. Also, I'm counting on time to aid in boosting the popularity of rotaries for aviation aplications. Glad, however, to have your confirming thoughts on this subject. I just didn't want to be thousands of dollars 'stupid'.

[Nathan Gifford]

...I just didn't want to be thousands of dollars 'stupid'...

Heck, you're already there! You are going to get lots of stares, eye rolls, etc. along the way. Wimp out! Just tell them you are building a boat until it really starts looking like a plane...

[tonyslongez]

I would just like to add, I'm also using a rotary. (13b new turbo housings) I would like to bring up one very important fact here that I rarely read about in forums. It's pretty obvious and I'm not trying to insult anyone's intelligence

 

The rotary has 3 moving parts. Lycoming, 52 for a standard 4 banger. A friend of mine was over the house tonight looking at the Long Ez with the engine mocked up on the back of it. He owned a cessna and brought up a very good point. Let's say you buy a brand new engine from Lycoming (which he did) and now you expect this thing to go to its TBO, right? Well O.K. sure. They do that, but do you know how much maintenance is involved nursing that engine to its 2000hr TBO? Jugs, magnetos, rocker arms, push tubes: the list is endless. He spent almost half the money in maintenance it cost to buy the engine new. I really don't think in the end it's going to hurt an airplane's resale. If anything, as people become more aware of the rotary engine your resale is going to go up. I'll bet anything you want on that. Who needs an A&P mechanic when you only have 3 moving parts? Gets rid of alot of guess work.

lycomings slogan should read

 

"Lycoming trying to come apart 2500 times a minute"

 

Tony

[Marc Zeitlin]

..... Who needs an A&P mechanic when you only have 3 moving parts? Gets rid of alot of guess work.

Does anyone who keeps bandying about the claim that rotary's have only 3 moving parts have any statistics on how much less engine maintenance the Mazda rotary engine cars need in comparison to say, flat four opposed engine Subaru's? Or any other 4 cylinder car? Did Mazda EVER make any claims of their engines being more reliable than any other engines? I didn't think so.

[tonyslongez]

Marc

 

The bandying that is usually thrown about is generally directed toward LYCOMING, not other four cylinder water cooled CAR engines. Although, the fact still remains: 3 MOVING PARTS. I don't care how you slice it- 3 will be more reliable than 40+ and if you can't see that look at the rotary's big brother: it's called a turbine. Maybe you've heard of those. I don't see 40+ moving parts on them either, do you? And we would all like to have the level of reliability of a turbine, right? Alot of guys that are crying about the rotary are just pissed because they just realized they could've purchased a more reliable power source with less money and a longer TBO. Stick with your Lycoming, or Subaru, or whatever you have. That's your choice. In the end, I rebuild my motor with a 15$ set of sockets and a torque wrench. Try doing that with a piston engine. good luck!!!

 

Tony

[John DiStefano]

Where it is true that a rotary has fewer mechanicals (moving parts) compared to say Lyc's 20-some-odd parts in the valve train, engines DO fail for other reasons. I guess you really need to look at failure rates of ALL the engines components, not just the mechanicals.

 

BTW, that's a pretty good leap going from a Wankel rotary to a turbine

[tonyslongez]

Jon

 

you really think that is a big leap? I agree we have to look at the failure possibilities of peripherals, but things are really comming around now. We are making leaps of progress in reliability and performance. As far as I can tell, the rotary is spinning the rotors, maybe not in a perfect circle but certainly not stop and start. I believe it sits right in between a piston engine and a turbine. It's as close as we're going to get to a turbine without beeing a turbine. Unfortunately it produces heat like a turbine as well but not quite as thirsty. That's just how I see it.

 

Tony

[Chairboy]

Wankel rotaries in autos have had a rough go at it. One of the mods for aviation rotaries that I've read about is disabling the scavenger oil pump that sacrifices a little bit of dirty crankcase oil to the gods of 'at least a little bit of lubrication' and replaces it with a bit of two stroke oil. Seems like a great way to increase the lifespan of the apex seals, for one, the most often targeted component in these engines.

[Nathan Gifford]

If you read around on a/c engines, there is some debate on whether pilots run their engines with long life in mind. There are claims, maybe even evidence, that a/c engines are quite reliable and possibly not maintenance hogs when run correctly.

 

The other thing that a/c engines have is a wealth of operational experience. There is an absolute wealth of experience of alternative engines running in autos, but not aircraft.

 

Aircraft and cars not the same animal. That said, there are some nice conversions like the Eggenfellers' Subaru conversions, and Mazda conversions is getting quite close. For pusher configs things are looking better thanks to builders like John Slade, et al.

 

I am leaning towards Subie or Mazda installations. The trick here is making sure that engine will keep the only fan on the aircraft turning.

[Marc Zeitlin]

The bandying that is usually thrown about is generally directed toward LYCOMING, not other four cylinder water cooled CAR engines. Although, the fact still remains: 3 MOVING PARTS. I don't care how you slice it- 3 will be more reliable than 40+ .....

And you determine this how - by induction? Other than handwaving, is there ANY evidence anywhere that rotary engines (wankels) are more reliable, once built up into something usable, than piston engines of ANY type? If so, I'd be glad to see it, and glad to consider using a more reliable engine, with a longer TBO, believe me. But if all you've got is "well, it's obvious, isn't it", then that doesn't cut it in the world of science, evidence, and proof. Now, you're perfectly welcome to your religion, but admit that that's what it is.

 

and if you can't see that look at the rotary's big brother: it's called a turbine. Maybe you've heard of those. I don't see 40+ moving parts on them either, do you?

Other than having parts that move in a vaguely circular motion, there is no familial connection between gas turbine engines, which run on the Brayton thermodynamic cycle, and wankels, which run on the Otto thermodynamic cycle. One is continuous combustion, and one is intermittent. No comparison.

 

And we would all like to have the level of reliability of a turbine, right?

Absolutely. But without the fuel burn or expense. But this has nothing to do with Wankel engines, because they're not gas turbines.

 

Alot of guys that are crying about the rotary are just pissed because they just realized they could've purchased a more reliable power source with less money and a longer TBO.

I've flown 338 hours in the past 3.5 years. There are a couple of auto engine conversions in canards that have flown that much, and reliably, but it's certainly not the norm. I would have liked a Subaru in my plane, but I wasn't willing to be the first to do it, and given the lack of evidence of reliable operations of either Subarus or Mazdas in canard pushers, I'm still glad I went the direction I did. When you've flown 100 hours/year for 3 to 5 years running, without having to perform any major surgery, I'll be happy to consider copying your engine installation.

 

Stick with your Lycoming, or Subaru, or whatever you have. That's your choice.

Why, thank you for the permission.

 

This thread was reanimated by someone asking about resale value. The answers that he got were accurate with respect to that - the resale value will probably be lower, but the cost of the build will be lower too. What was forgotten is that aircraft engines, over the past 5-15 years, have been APPRECIATING in value - you can sell a runout O-360 for what you would have purchased a 500 hour engine for 15 years ago. I don't think that has happened, or will happen, with auto engine conversions. Calculating the cost of ownership of a homebuilt aircraft is not simple - it is extremely dependent upon what assumptions you make regarding the cost of money, the appreciation rate of the engine and/or airframe, and many other factors. Maybe auto engines are more cost effective in the long run, and maybe not. I could cobble #'s together to prove it either way.

 

Use an auto conversion if you like - there's nothing wrong with doing so, and you'll have a good time trying to figure out how to make it work (just as I did with my Lycoming engine). But don't do it on the false premise that there's some intrinsic advantage, either in reliability, cost, or fuel economy. All of those claims have yet to be substantiated by evidence.

 

In the end, I rebuild my motor with a 15$ set of sockets and a torque wrench. Try doing that with a piston engine.

I have - a couple of times. One four cylinder motorcycle, and one car. No big deal.

[Nathan Gifford]

Like Marc said getting back to origins of this thread, is there are a lot of factors regarding resale value of the aircraft. Certainly it will be easier to sell a well maintained aircraft with a well maintained certified powerplant, just like it is probably easier to sell tractor aircraft than pushers (FAMILIARITY).

 

Familiarity has a great deal to do with aircraft resale. If you are asking someone to plunk down big bucks on an airplane, unless they know a great deal about what goes into that particular model they are going to pick an aircraft as similar as it can be to ones they like to fly.

 

Experimantals compound this problem because there isn't a book of standards to same level as certified aircraft. They have to comply will all applicable FAA regs, but that is not the same as having a staff at a company that collects, collates, develops and advises solutions for manufactured aircraft.

 

While resale is important to us all, you may want to ask the question, "do you think you will be selling anytime soon?" A lost medical, a move, or family additions may cause these things but if you won't be selling anytime soon do worry so...

[Dolan]

I am experiencing the real value of these sites more and more. In response to my question regarding whether my potential purchase of a Cozy III already equipped with a rotary would likely depreciate, I received more input in 24 hours than I, personally, could have conjured up in days. BTW, if I can make the deal, I'm going for it. But I am equipped with a lot more knowledge than I would have before. Thanks so much!!

[David Staten]

In the end, I rebuild my motor with a 15$ set of sockets and a torque wrench. Try doing that with a piston engine.

I'm sorry... I like the rotary.. I rebuilt one, have a second one for a spare, and have torn a total of 4 apart, and I can assure you the above statement is pure BS.

 

The big 2 1/4 inch nut on the back ALONE requires 300 foot pounds of torque. The wrench that can do that is a THOUSAND dollars unless you can borrow one as I did. The NUT requires a socket that cost me $50 bucks new and wasnt available for much cheaper used. Torque multipliers that allow ordinary torque wrenches to reach that torque range rarely sell for under $100 on ebay and cost many times that value new. I needed a heavy duty impact wrench to get that big nut off in the first place, not my ordinary cheap harbor frieght one. That big wrench cost nearly $70 at a pawn shop. I tried a big LONG cheater pipe.. all I did was move the engine around.. the bolt held.

 

I have a full set of metric impact sockets. I have a set of micrometers for measuring wear. I have gap gauges, thread gauges, feelers, a dial indicator.. and I had NONE of this when I started this project.

 

I can assure you it costs a HELL of a lot more than a cheap $15 metric socket set from harbor freight if you want to do the job right and without breaking tools or yourself.

 

I'm very pro-rotary. Im installing one. But I am just as annoyed as Mark when folks "wave their hands and proclaim to the masses 'three moving parts'" That is a gross oversimplification and naive. It does the rotary community a disservice when that gets emphasized above all else.

 

Dave

[Chairboy]

(waves hands)

 

Three moving parts! Three moving parts!

[tonyslongez]

Dave

 

You'll have to forgive my last post I forgot to mention that, I do infact have alot of the tools you described above and then some. Not all of which I used to rebuild my engine. As far as the impact was concerned I simply went down the street to a trany shop and gave the guy 10 bucks to take off the large nut in the back . Borrowed a nice torque wrench from my neighbor and used a rather rudamentory set of metric sockets hardly anything fancy and nothing to write home about. And yes 3 moving parts over simplyfied? Hardly, unless I missed something when I rebuilt my motor I only saw three, we'll call them Major parts. Two rotors and an E-shaft 1, 2, 3, yup that equalls three allright. Now lets make sure we are all talking the same lanquage here no redrive and a non stock intake manifold and non turbo sure you can add more moving parts but the core of the engine has 3. VERY SIMPPPPPPLLLLLLEEE. I'm not arguing here I'm sticking up for the rotary engine how can anyone say that is "injustice" are you kidding me ? some of these morons I've talked to! you have to break it down literally to the lowest common denominator forget thermodynamic cycles and all that other stuff. Some of these guys can barely see past the damn propeller. Yes 3 moving parts thats how I describe it to someone who knows nothing about a rotary engine, that gets the wheels turning. Then, they start looking into it themselves then the industry thrives. I'm not going to apologize for anything. You guys want to pick my posts apart have at it. I have an airplane to build and not alot of time to play semantics.

[David Staten]

Dave

(CONDESCENSION SNIPPED)

. VERY SIMPPPPPPLLLLLLEEE...

(CONDESCENSION SNIPPED). Yes 3 moving parts thats how I describe it to someone who knows nothing about a rotary engine, that gets the wheels turning.

 

Im all for informed discussion and informed decisionmaking, and while I've come across some very informative persons with regards to the rotary, I also seen more than a few who seize on the notion that 3 moving parts AUTOMATICALLY confers improved reliability and efficiency.

 

I'm not accusing you of this directly, and I'm in no position to seek an apology from anyone. This is more of an open issue. Right now, the jury is out on the reliability aspect, and much of that is the result of the peripherals added, not the core engine itself, but an engine failure and power loss leading to an off field landing or WORSE is a bad event, regardless of wether the core engine or an accessory was at fault. I am speculating that Chris and I will have our rotary fired up and ready for taxi testing within the next 60 days. We are doing a few unique things, on a block that we rebuilt and modified ourselves.

 

I will not kid you that money was a BIG motivator on our powerplant choice and we did our homework. I have read every scrap I can about the rotary, others installs, others experiences good AND bad, and about auto conversions in general. In this vein, I consider myself an advocate for rotary power, but I am cautiously optimistic about how well it will work.

 

Then, they start looking into it themselves then the industry thrives. I'm not going to apologize for anything. You guys want to pick my posts apart have at it. I have an airplane to build and not alot of time to play semantics.

I called BS on the notion that a torque wrench and a $15 set of sockets is all you needed for a rebuild. Thats not semantics. Thats potentially misleading. My OPINION is simply that while advocating in favor of the rotary, you were a little enthusiastic and stretched it a bit. I don't think you intended to lie or intentionally mislead anyone.

 

The same sort of embellishment is happening with fuel burns, power generated, installed weight and so forth in other settings. There's really not that much DATA out there in an aviation setting, so what little bits we have are precious. If someone who doesn't KNOW any better starts basing decisions on little embellished snippets such as these and doesn't get the straight scoop, they are going to feel lied to regarding the rotary... hardly something that will increase our ranks. Its about knowing the risks and weak points and working with them, not putting your head in the sand.

 

Mark isn't a rotary basher either. He's simply a cautious engineering type. I dont always agree with him, and some folks have trouble with the way he says things, but I must admit I find his postings to be rational, accurate when dealing with facts, and defensible when dealing with opinions.

 

I apologize if this has turned into something personal.. that was not my intent. My intent was to set the record straight, firmly, regarding what I felt was misleading information.

 

Dave

[tonyslongez]

Dave

 

No apology needed buddy, I know what you meant. We are all family here. Its hard to see the tonque in cheek when making the type of post I made earlier. I too have done my homework on this engine. I made what I thought where good sound judgements on the rotory's reliability. (back to this original thread resale value). I'm a machinist, I machined titanium 6al-4v studs for my motor. I'm using a dry sump, it's N/A with Tracy's redrive and Em2 Ec2. I'm as cautious as the next guy about this motor. We should be running as well in about 6-8 weeks. The test stand is complete and ready for the engine to be bolted on.

 

I also seen more than a few who seize on the notion that 3 moving parts AUTOMATICALLY confers improved reliability and efficiency.

 

Dave

 

I'm certainly not one of those people. If the person I'm talking to wishes to discuss further the possibilities of the rotory in flight, I can give them more than enough information to chew on and certainly throw in the "it's not easy, the engine is simple, but certainly not easy" that is always one of my disclaimers. There is alot of work involved and I commend everyone trying it. We are looking at the birth of a new power plant, something we in the homebuilt world have needed for a long time now. Are we going to have failures? sure, I'll bet Lycoming wasn't so reliable when they first started either. good luck with your project I'm sure I'll see you at Oshkosh at some point.

 

Tony