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Alternate Engines


xanman31

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Forget the VW. You'll be wanting 150-200 HP

Unless you're into economy, which IMO is one of the key factors for why the Long-EZ is such a great design (Rutan derivative canards in general). This is the only reason why I look back now and then from my Cozy Mark IV project.

 

(Who would have thunk we'd have an 'Alternate Engines' section under the Long-EZ sub-forum. Interesting... :confused:)

Jon Matcho :busy:
Builder & Canard Zone Admin
Now:  Rebuilding Quickie Tri-Q200 N479E
Next:  Resume building a Cozy Mark IV

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...The vacuum bagging is the way to go, I dont know why more builders do not use it.

Because it's a lot more work for a relatively small weight savings. Probably on the order of 10-20 lb. total on a whole plane. Contact layups are a lot simpler, and don't require the equipment and extra materials (cost).
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Because it's a lot more work for a relatively small weight savings. Probably on the order of 10-20 lb. total on a whole plane. Contact layups are a lot simpler, and don't require the equipment and extra materials (cost).

I don't about that one, Marc. I've been bagging every chance I get. There is some additional expense, true, but every time I peel everything off, I can feel the weight I'm saving. It also eliminates any air bubbles.

 

I quess from my perspective (seeing as I started the project this way) it's no big deal. I'd be willing to put my layups against anyones when it comes to weight and quality. I'm not bragging about my skills ........... instead I'm talking about the extra quality as a result of the technique.

 

As far as any additional time, I can't tell. I'm currently averaging a chapter per month and I really don't think I'm pushing it.

T Mann - Loooong-EZ/20B Infinity R/G Chpts 18

Velocity/RG N951TM

Mann's Airplane Factory

We add rocket's to everything!

4, 5, 6, 7, 8. 9, 10, 14, 19, 20 Done

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rotaries are worth looking into. You get the power for far fewer yen than certified sixes, yes there is the redrive and tracy can help you with that one.

You can stack up a lycoming and a rotary and talk all day long about the pro's and con's, in the end, the mazdaratti will give you the hp with fewer operational costs and yes, mogas folks.:P

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Great Picture!

Amazingly some people still don't get it!

What is there to "get"? While in theory, lower parts count may reduce failure rates, the data does not support the notion that rotary engines have failure rates any lower than any other engines.

 

There's nothing to "get". If you like rotary engines, that's fine - they seem to work well in aircraft, if you don't mind having to search for mogas (especially out west) and having slightly higher fuel burns than aircraft engines, but the implication that you will have fewer failures due to the parts count (and moving parts count) is not born out by the epidemiological data.

 

Before me there was Ron Gowan who put a couple hundred hours on a rotary LEZ in the mid 90s.

Before swapping it out for a Lycoming, as Joe Hull and Bulent Aliev are doing with their COZY's.
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What is there to "get"? While in theory, lower parts count may reduce failure rates, the data does not support the notion that rotary engines have failure rates any lower than any other engines.

 

There's nothing to "get". If you like rotary engines, that's fine - they seem to work well in aircraft, if you don't mind having to search for mogas (especially out west) and having slightly higher fuel burns than aircraft engines, but the implication that you will have fewer failures due to the parts count (and moving parts count) is not born out by the epidemiological data.

 

Marc, as a mechanical engineer don't you find the Wankel engine, that tends more towards a turbine (hence higher fuel burn) than a "reciprocating" (in FAA speak), an elegant machine? [i had to list my engine as a "reciprocating" even though there are no parts in my engine that do that].

 

Me being of the electrical variety, prefer the simple moving mechanisms with electronic control.

 

You are right in that the parts count alone is not an indicator of overall reliability, as most actual failures of both rotaries and reciprocatings are rare and not usually in the engine itself. (Except for those rare crankshaft, rod and exhaust valve failures).

 

Before swapping it out for a Lycoming, as Joe Hull and Bulent Aliev are doing with their COZY's.

I don't know that Gowan ever got his Long-EZ flying again with any engine. Maybe he did. I thought he bought a Vari-EZ to fly while he was working on the Long-EZ. But that was a long time ago and I haven't heard anything lately....

 

Joe suffered from a broken spark plug - IMHO he was using the wrong spark plugs. Bulent got frustrated with the EFI.

 

I've had almost no issues, but I took the lowest risk approach with my install.

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Marc, as a mechanical engineer don't you find the Wankel engine, that tends more towards a turbine (hence higher fuel burn) than a "reciprocating" (in FAA speak), an elegant machine?

In some sense, yes - fewer moving parts is more "elegant", from an engineering standpoint. But by that measure, a single transistor is more "elegant" than a 2 million gate CPU, but it's hardly as useful :-).

 

It's not a turbine, though, as it still uses the Otto cycle, rather than the Brayton cycle. The inefficiencies have to do with the large sealing are, imperfect combustion chamber shape, and incomplete burning and concomitant high exhaust temperatures, rather than the cycle used.

 

You are right in that the parts count alone is not an indicator of overall reliability, as most actual failures of both rotaries and reciprocatings are rare and not usually in the engine itself. (Except for those rare crankshaft, rod and exhaust valve failures).

That was my point - if the advantage is in the elimination of parts that almost never fail anyway, and the histogram of failures indicates that the part that you still HAVE to have are the ones that fail, then you really haven't gained anything. There's no real weight savings, there's no real fuel savings, and by the time you get through with it, there's not a great deal of cost savings, either.

 

I wish I was wrong.

 

I don't know that Gowan ever got his Long-EZ flying again with any engine.

Well, I've seen him in his Long-EZ at OSH the last few years (with a Lycoming) and at the Marysville fly-in this year.

 

Joe suffered from a broken spark plug - IMHO he was using the wrong spark plugs. Bulent got frustrated with the EFI.

For whatever reasons, they have chosen to go back to a standard aircraft engine. My point was not that Lycomings are "better" than rotaries - only that it's not obvious that rotaries are "better" than Lycomings.

 

I've had almost no issues, but I took the lowest risk approach with my install.

And unlike me, there are those who've had no issues with their Lycomings :-). But one data point does not a trend make :-).
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It's not a turbine, though, as it still uses the Otto cycle, rather than the Brayton cycle. The inefficiencies have to do with the large sealing are, imperfect combustion chamber shape, and incomplete burning and concomitant high exhaust temperatures, rather than the cycle used.

 

True. I think the RX-8 motor with side exhaust ports addresses the latter issue.

 

We've had these conversations before, it's always fun to revive them once in awhile.

 

The rotary can be aggressively leaned (I don't practice that yet, but Tracy Crook does). I believe the BSFC will always be a marginally unfavorable compared to water-cooled reciprocatings but may not be significantly different than air-cooled reciprocatings.

 

Since this thread is under "Model Specific - Long-EZ", I forgot to mention my page with some fundamentals for installing a rotary in a Long-EZ.

http://www.bridgingworlds.com/LEZ13B/LEZ13B.htm

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I don't think that there are enough rotaries out there to do a cross analysis against the traditional piston engine. There is an impressive level of mechanical simplicity in the rotary which cannot be argued at any level.

 

I'm building with a 20B NA as my target power plant. Some say I could get close to the same performance out of a 13B with a turbo but the turbo injects (no pun intended) a level of mechanical complexity that kind of defeats my goal of mechanical simplicity. Parts break ....... turbos break.

 

What sealed the deal for me was John Slades rotary application w/Turbo. The turbo failed and some of the impeller material was ingested into the engine. John flew it home.

 

So what did I get out of Johns experience:

1. Turbo is another failure point that I'm not willing to take on.

2. Even with the failure of the turbo, the engine continued to run indicating a benign failure rate.

3. It was not an expensive repair involving a large amount of down time.

 

I'm certain that this will be the best choice of power plant for my application.

 

Seeeeeeeee ............. I get it!

:D

T Mann - Loooong-EZ/20B Infinity R/G Chpts 18

Velocity/RG N951TM

Mann's Airplane Factory

We add rocket's to everything!

4, 5, 6, 7, 8. 9, 10, 14, 19, 20 Done

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I don't think that there are enough rotaries out there to do a cross analysis against the traditional piston engine.

Of course there are. Do Mazda rotary engined cars have engine failures less often than piston powered cars?

 

There is an impressive level of mechanical simplicity in the rotary which cannot be argued at any level.

It can't be argued that it's not less simple, in the sense of having fewer moving parts, but from a failure rate standpoint (which, of course, is only ONE of the factors used in choosing an engine), the argument is hardly clear in either direction.

 

What sealed the deal for me was John Slades rotary application w/Turbo...

Big deal. I've had electronic ignition failures that didn't keep me from continuing a 5 hour flight from OSH to PVC (and which took an hour to fix). My vacuum pump could roll over dead and not stop the engine from running. I could name 5 things on my Lycoming, and 5 things on your rotary, which could stop the engine dead at any time. And would be on the same order of likelyhood of occurring.

 

Using John's airplane, which has flown a total of less than 100 hours in approximately 4 years, as a positive example of anything is myopic at best. I fly 120 hours/year, and could fly a lot more (if I had places to go, and the time to do it). Nick Ugolini puts 300-400 hours/year on his LE. Please find me a couple of rotary engine aircraft (canards, preferably), which fly that much.

 

I'm certain that this will be the best choice of power plant for my application.

You may be "certain", but you have no evidence on which to base this certainty. It's a belief, not a fact. There is, of course, no sense in arguing religion with a fanatic.

 

Seeeeeeeee ............. I get it!

:D

No, you've made your mind up already, and facts no longer affect what you believe. Similar to the canopy hinging "debate". You pick and choose a small subset of facts from the overall pool, while ignoring any that detract from your existing belief structure.

 

Use the rotary - clearly it can be made to work reasonably - Perry Mick has shown that, as have a very few others (in canards).

 

However, since Ron Gowan, Joe Hull, Bulent Aliev, and Greg Richter have all removed rotary engines from their canard aircraft and replaced them with something else (3 of 4 with Lycomings), and the extant flying canards with rotaries are fewer than those that HAD them and got rid of them (I can now only think of Perry, John, S., and one more in South Carolina which flew a few hours and is still not out of Phase I after 4 years), and average far less time/year than aircraft with Lycoming engines, it seems clear that any supposed advantage is ephemeral at best.

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I would like to include "except for mazda" in my thread title.

Ha ha haaaaaaa!!!!!!! Another hijacked thread.

Don't you get it.

 

Perry, we'll have to start a new thread. We can't play here anymore. :D

T Mann - Loooong-EZ/20B Infinity R/G Chpts 18

Velocity/RG N951TM

Mann's Airplane Factory

We add rocket's to everything!

4, 5, 6, 7, 8. 9, 10, 14, 19, 20 Done

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I think the strength's of the rotary are appreciated most by their enthusiasts. Loss of coolant, no problem, fly her home and hopefully do a low budget overhaul. There are no inherant weaknesses in the crank, and certainly no connecting rods to grenade. Gee wiz, they are both going down with loss of ignition signal.........both going down with loss of fuel pressure........valve train will not be a problem on the rotary, but perhaps a lyc closing in on overhaul time. No redrive problems with a lycoming, potential that is. Most of us know a rotary manufactors a lot of heat, dealing with it can be challenging. Maybe the costs involved in overhauling a lycoming are what rotary folks like most about their mazdaratti's? Simplicity, ease of overhaul, yes, strong points...........personally, and although I am a strong rotary enthusiast, if I had to restart either in flight, it would be the lycoming. (trying to be honest here) My choice to use a rotary lies half in economics, half in knowing there will always be those who will be critical.

If it performs in the mission my aircraft was built for, it can't be bad.

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