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Question for the Rotary RV'rs

FLEXCopMNPD

Member
I am in the beginning stages of RV grin development (working on the emp in between military deployments) and I am mulling over the choice of powerplants. The more I read about them the more I want to hang a rotary off of the nose. :D

I have devoured everything I could find in the Alternative Engine thread and have read just about every website that has been referenced here and ones I have found through Mr Google.

I have several questions, the main being if you had it all to do over again would you go the same route, lessons learned and things to avoid, and what sort of performance/ fuel burn are you seeing.

Any and all guidance is appreciated by those who are using or building with a rotary, or those with information on how to contact those people :D

Not really interested in hearing anyone comment on "Why would you want to do that?" or any bashing of any kind.
 
I originally wanted a rotary in the Cozy MKIV I built. Purchased a JDM 13b Turbo Cosmo engine for $900 and found it to be pretty much trashed when I disassembled it,,,,I was able to part it out and recoup about $150. Visited Bruce Turrentine of East Coast Rotary and had him build a new 13b Renesis for me,,,,,$7K. Built the mount but still needed ECU, re-drive, custom intake and exhaust manifolds, etc,,,, would bring it up to almost $12K. Read of all the problems people have getting it dialed in and reasonably safe and reliable along with resale value and decided it was probably a bad idea for me. Sold the Renesis at a loss of course and we ended up buying a Lycoming and bolting it in per plans with no problems. Do not kid yourself into thinking alternative engines are cheaper to install and maintain,,,,they are not. By the time you are all done with an alternative engine installation, you will be $$ where you would be $$ with a good used Lycoming. As a benefit with a Lycoming powered home built, you will enjoy its reliability, simplicity of installation, and maximum resale value if/when you sell. Been there, done that. Some folks like the challenge of the install and constant tinkering and tweaking to get it right,,,,,,if you are one of those type of builders,,,,,gof for it!;)
 
Brian,

Your best bet for rotary information is at:

http://www.flyrotary.com/

Join the mailing list, and ask your question there, you'll be welcomed, and get an honest answer to your questions.

Tracy.

I would not count on getting pure "honesty" over there,,,,,,,like I said: Been there and done that,,,,,including the flyrotary list. ;)
 
Talk to Tracy Crook with Real World solutions. He really knows his stuff. Alt engines are not for everybody but for those of us who love to tinker they are great and can be very rewarding.
 
I ordered the Aviator's Guide to Mazda Rotary Conversion and The Mazda Papers from Tracy's site. His site and a few others really pushed me over the edge to wanting a rotary powered RV 8. Plus those two that were in the RVator that were painted up like a Spitfire and P40 Warhawk didnt hurt either. :D
 
Rotary Engine

Not bashing the idea but you need to do LOTS of research before you make this decision. I would suggest you read the RVator newsletters Third Issue 2004 and Second Issue 2005 which discuss two RV-8s using rotary engines.

One paragraph summarizes the comparative testing between the rotary airplanes and the Van's demonstrator RV-8:
The rotary airplanes were ultimately faster than our RV-8A and very slightly quicker than our RV-8. They out climbed both reciprocating airplanes. But, in all cases, even at equal speeds, they burned more fuel than the reciprocating engines. They weight slightly more, which may not be the most accurate comparison, because all the airplanes were not comparably equipped. The rotaries were definitely noisier inside and out.

I have been interested in rotary aircraft engines for over 20 years and have some old Curtiss-Wright and Deere papers discussing their programs. I came to the conclusion that the rotary aircraft engine is a wonderful idea that has not been translated into wonderful hardware.

I chose a traditional aircraft engine for my RV-9A, working on the fuselage.
 
By the time you are all done with an alternative engine installation, you will be $$ where you would be $$ with a good used Lycoming. As a benefit with a Lycoming powered home built, you will enjoy its reliability, simplicity of installation, and maximum resale value if/when you sell. Been there, done that. Some folks like the challenge of the install and constant tinkering and tweaking to get it right,,,,,,if you are one of those type of builders,,,,,gof for it!;)

Lots of people do indeed spend more on an alternative engine than a Lycoming but some people get things right and have decent performance and reliability while still keeping cash in the bank. I've had the $20K I didn't spend on a Lycoming/ Hartzell in investments for 7 years at about 10% return so that has doubled now.

Works for me and even if I have to rebuild the Sube at 500 hours and it needs everything, it will be under $2K.

I was visiting my friend with with his ECI/7 last weekend. He was installing 4 new jugs because he can't sell it with the AD outstanding. He's going to lose money on that one. It's not roses for everyone with traditional engines but I still agree it is probably the best choice for most builders.

I'd second the cautions about plunging into alternative engines too. Do plenty of research first.
 
Alt Engines

I've come full circle and believe the Lycoming is the way to go. I've flown behind a well mannered Subabu engine and followed one down the highway for 100K miles. I flew 200 hours under a Rotax. I even flew a heli with a 2 stroke Evinrude I bought off the back of a boat. BUT, the Auto engine often adds the complexity of a reduction drive. The auto engine was not designed for continuous output at the power levels required. It may deliver 200 hp to get the car rolling but only need 30 hp and 1800 rpm to maintain 75 mph. If I have an A/C engine issue 900 miles from home I can usually find a mechanic on the field whose insurance covers him touching my engine. I'll give you that the A/C engine is 60+ year old technology but the design prevails for a reason. And the Magneto ignition system(s) doesn't need much if all else fails.
Fuel and fire. It doesn't take much to keep an engine happy.
 
I've come full circle and believe the Lycoming is the way to go. I've flown behind a well mannered Subabu engine and followed one down the highway for 100K miles. I flew 200 hours under a Rotax. I even flew a heli with a 2 stroke Evinrude I bought off the back of a boat. BUT, the Auto engine often adds the complexity of a reduction drive. The auto engine was not designed for continuous output at the power levels required. It may deliver 200 hp to get the car rolling but only need 30 hp and 1800 rpm to maintain 75 mph. If I have an A/C engine issue 900 miles from home I can usually find a mechanic on the field whose insurance covers him touching my engine. I'll give you that the A/C engine is 60+ year old technology but the design prevails for a reason. And the Magneto ignition system(s) doesn't need much if all else fails.
Fuel and fire. It doesn't take much to keep an engine happy.

The Lycoming is a the best choice for most builders but you are in error stating that auto engines are not designed for continuous high hp output. If you can produce any solid data about premature wear or failures based on the higher duty cycle, I'd love to see it. The basic assumption about auto engines only being reliable over the long term at low hp levels is invalid and ignores the real world testing the OEMs do along with high duty cycle use of the engines in Europe or in marine use.

All modern designs are in fact designed and validated to higher standards than certified piston aircraft engines and this is born out in service. I don't see premature wear or failures on engines used in aircraft at all when operated within factory temperature and AFR limitations. One of my client's Rover V8 powered Bearhawk just passed the 1000 hour mark without the engine ever being touched other than plug and oil changes. Still uses no oil between changes.

I have many other clients around the world flying auto engines. These include Subaru, Suzuki, Honda and Chevy. Most have few problems with the engine core. Titan Aircraft use Suzuki and Honda V6 engines in their aircraft with good success as an example of more mainstream use from a kit manufacturer.

You can read some previous discussion here: http://www.vansairforce.com/community/showthread.php?t=65006
 
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The Lycoming is a the best choice for most builders but you are in error stating that auto engines are not designed for continuous high hp output.

And to get that high output, the auto engine is running at near double the Lycoming's 2700 rpms. And it sounds like it! Quite annoying, unless there is some long muffler systems hanging underneath the airframe. I'm just pointing this out, as I live next to an airport. :)

L.Adamson --- RV6A
 
I would do it again

I have several questions, the main being if you had it all to do over again would you go the same route, lessons learned and things to avoid, and what sort of performance/ fuel burn are you seeing.

Any and all guidance is appreciated by those who are using or building with a rotary, or those with information on how to contact those people :D

Not really interested in hearing anyone comment on "Why would you want to do that?" or any bashing of any kind.

I would do it again. About half of everything you hear about alternate engines (from both sides) is true, but I'm not going to tell you which half :)

I just found this great video of Gary Spencer's long EZ with a chevy. Pretty much says it all:
http://pursuitofflight.com/longezv8.html

To summarize, you will definately save money over the long haul, but not very much on the initial installation.

It is a LOT of extra work, but pays off. It added at least a year to the project. The first couple hundred hrs I was putting in almost 2 of work for every flight hour. Now I rarely do anyting besides regular maintiance. I have carefully detailed all my issues on my web page if you care to have a look (link in my signature).

If I were to re-do it now, I would pretty much do the same things. Now that the renisis engine is available I might consider that instead of the 13B. I might consider p-ports instead of the turbo, but I have been liking the turbo lately. I am making over 240h.p. right now when I care to burn that much gas (around 25gph). BUT! It has taken me the better part of 6 years flying to understand what it takes to push the engine and turbo that hard.

My installation weighs less than one with an O-360 and CS prop.

Fuel burn is just so hard to give numbers that have any meaning. I can burn anywhere between 5 and 25 GPH depending on conditions. Look, all i.c. engines are more or less in the same ballpark reguarding efficiency given the same operating conditions. Energy is energy and thermal expansion is thermal expansion. ALL lyc, rotary, and other alternate engines are going to have a BSFC between .45 and .65 (or so) and that range only reflects differences in operating conditions (ROP, LOP, compression, supercharge, themperature, ignition timing, exhaust tuning and back pressure etc). Most real differences in fuel burn have more to do with the airframe and its drag. However, those things have been better worked out on certified engine installations...

Anyway, to better answer the question... next to a similar airplane at the same speed I will be burning about 10% more than a pistion engine if we are both running LOP. Part of that is probably cooling drag. However, I still spend less money on fuel because the vast majority of all the fuel I have used has been MOGAS. "But most lycs can run MOGAS if they wanted as well" you may be temped to say. But very few actually do, and the reason that they dont is because of the feared 'MOGAS Gremlins'. Long story short, MOGAS Gremlins cannot harm a well-designed fuel system like mine or the one you would no-doubt install if you were doing an automotive installation.

Above comments about noise... sadly, too true. Somewhat louder in flight, louder from the ground. Less pleasing higher pitch that grabs your attention more than any increase in volume. However, when it winds up and gets moving I have been told that it sounds "really awesome!"

I also agree with someone's comment to follow the FlyRotary list. Can't beleive everything you hear, but at least the author of anything there will believe what they are saying is true. Also check in on some automotive tuning/racing forums especially for low down on the rotary. If I were to admit on one of those forums that I am making only 240h.p. they would tease me. That little 190 lb. engine block is truly remarkable in the amout of power the car racers tease out of it. I saw a video of one (yes, a 2-rotor) on a dyno making over 900 SHP! (300-450 RWHP is more typical of the amature guys - and most of that is probably B.S... But still

Like others have said, its not for everyone. Do it more because you want to and find it interesting than any other reason.
 
I really appreciate your comments David and your last sentence really sums things up well for most of us who have gone down the alternative engine path.:)
 
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Hey Ross! Will you take over all my investments. Man, 10% a year for seven years is for me.

Bill

I've never trusted investment managers figuring if they were that smart, they would all be multi millionaires and wouldn't need a real job. I've seen enough friends lose money over the years using their services to trust my money with them. Certainly some do well, year after year for their clients.

If I guess bad and lose my own money I can kick myself at least! You only get a sorry from these folks if something they recommend tanks.

I have been very fortunate with most of my investments for the last 25 years. I do have an issue with one company though which might require legal action to remedy for breach of contract. We'll see how that one pans out. I don't win 'em all for sure but I've never invested directly in the markets, believing a huge freefall is imminent. Then again, I've been thinking that for quite a few years now... Nobody knows, simple as that.:)

I know one thing though, airplanes, cars and motorcycles are not what I'd call investments- well maybe time investments. Just use them to have fun and you won't be too disappointed.
 
"But most lycs can run MOGAS if they wanted as well" you may be temped to say. But very few actually do, and the reason that they dont is because of the feared 'MOGAS Gremlins'. Long story short, MOGAS Gremlins cannot harm a well-designed fuel system like mine or the one you would no-doubt install if you were doing an automotive installation.

But... it's kinda hard to obtain mogas on a cross country, even locally one has to haul a bunch of fuel cans around. I can get 92 oct no ethanol mogas at Lebanon, OR for 3.60/gal but still burn $25 to get there and back. Simpler to just use 100LL and be blind to the price.
 
I am in the beginning stages of RV grin development (working on the emp in between military deployments) and I am mulling over the choice of powerplants. The more I read about them the more I want to hang a rotary off of the nose. :D

I have devoured everything I could find in the Alternative Engine thread and have read just about every website that has been referenced here and ones I have found through Mr Google.

I have several questions, the main being if you had it all to do over again would you go the same route, lessons learned and things to avoid, and what sort of performance/ fuel burn are you seeing.

Any and all guidance is appreciated by those who are using or building with a rotary, or those with information on how to contact those people :D

Not really interested in hearing anyone comment on "Why would you want to do that?" or any bashing of any kind.

The cost depends on how much you are willing to do yourself. You can pay some one like Mazdatrix to rebuild an engine for about $3500. Or you can do it yourself for about $1000 in parts and gaskets. No machining required like piston engines. You just usually replace the rotor housings and seals. Very simple to do once you jump in. You will need to buy a gear box from Tracy for about another $3000. If you forgo the fancy EFI it can run on a 500 CFM Holley two barrel. The engine is extremely robust to say the least. Power is up to 250 with a p-port. The weight firewall forward comes out about the same as an IO-360. I have owned six rotary powered cars starting in 1973. Currently I have an RV4 with a rotary. I have edited the rotary engine newsletter for the last 12 years. We have about 100 flying all over the world. In that time I think I have answered or responded to well over 500,000 messages. I also wrote a book called How to Cool your Wankel as that was an early problem. Many people had trouble doing that back about 6 to 12 years ago. Now it is no longer a problem. We are still finding gear box problems with the 250 HP p-port and turbo engines but those are being solved as we speak. The 200 HP versions are absolutely reliable with as many as 2000 hours on them in gyro use,

Paul Lamar rotaryeng.net
 
Welcome to VAF Paul Lamar

Welcome to VAF Paul Lamar, great to have you here.

I urge anyone with an interest in putting a wankel engine into an RV to spend some time on rotaryeng.net - Mr. Lamar has put a lot of work into helping people develop safe installations - Lots of great material there.

Hans
 
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