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Corvair power

E28POWER

Member
I've been searching for first plane project, RV-12 is at the top of that list. The #2 plane at the moment, is the Zenith CH-650, very similar in many ways.

One of the draws to the Zenith, was the ability to use the Corvair engine.

I really like most things about the -12, except the cost of the 912S.

The Corvair is a little heavier than the 912, about 35lbs. I know there are some -12s flying with the Viking engine, which is about the same weight as the Corvair.

I'm not concerned about being LSA compliant, it'll be built E-AB.

Is anyone aware of a -12 being built with a Corvair powerplant?

The -12 is very economical, built not much cheaper to build than a -7, my #3 choice. I can build a 100hp Corvair engine for about $6k, plus engine mount, prop, etc.

Thoughts?
 
Corvair

I have a 3100 Corvair in an RV-3. Its a fun engine. Very smooth. Starts easily cold or hot. Never floods. Not as fast as an O-320; I get about 170 mph. About 1400 f/m climb. Speeds would be a little better if I could get the fairings finished.

Bill Newkirk
 
If you are sold on the Corvair, build the 601.

Larry, the 650 is the modern version of the 601, which was plagued with flutter issues.


If you want to build an RV and use a Corvair engine, then I’d recommend the -9 or 9A. The weight and horsepower will be a good fit, and you’ll have higher cruise speeds and a little more usable load.
 
Larry, the 650 is the modern version of the 601, which was plagued with flutter issues. QUOTE]

My bad. I had just awakened from a deep sleep. I knew he stated 650.
Retired folks sleep until 6am.

My comment should have went further in depth. I believe the Corvair package is just too heavy for the 12. And I do have a next hangar friend with a Pietenpol/Corvair package. Great sounding engine. I think you would be very unhappy with the completed project. Also, CG/loading would be an issue.
 
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I'm not 100% sold on the Corvair, but it has a lot of positives. I would love to run the new 912iS, but my budget cannot support that. I'm going pretty low budget as it is.

I wonder how the Viking flyers addressed any CG issues. I would have to build an engine mount anyway, maybe mounting it a few inches aft might resolve that, and relocating the battery.

I really like the Zenith 650, but it's slower than advertised, and is lacking in a few areas compared to the -12. The 650 kit is only $18k, but only $3-4k cheaper when you add options that are standard on the -12.
 
Having built and flown a 601 w/ a Corvair on a tight budget, my $.02 is that if money is the biggest factor, and you're set on a Van's product, you should go with a 12 and a 130hp viking. The Corvair was a perfectly fine powerplant, and I was very happy with the performance in the low-wing zenith, but only because I opted for the largest displacement version and what I felt to be the best 5th bearing option. I fabricated many parts myself instead of buying WW versions, and still ended up around 9-10k for the engine, and a couple thousand more for the rest of the FWF bits I couldn't fab myself. Seems like that compares pretty well with the Viking pricing, but they're already set up for the 12 and you'd be pioneering new ground if you tried to mate a Corvair to one.
 
I don't disagree with, nothing easier than going with an existing option. However, there is a first time install for any non-factory recommended engine. That's what's so great about E-AB.

I know it's really 2-3X harder than I think it is to install a Corvair engine. I'm just not finding any really good reasons not too.

I'm probably 12 months from actually starting a project, so maybe I'll come to my senses. I'm still not giving up on the corvair idea though.
 
The Corvair was a perfectly fine powerplant, and I was very happy with the performance in the low-wing zenith, but only because I opted for the largest displacement version and what I felt to be the best 5th bearing option.

What did you see for cruise speeds with the 601? If you remember.
 
I cruised at about 115-120 mph indicated. Top speed was about 130 mph all-in at sea level. A friend just bought a factory-built 12 and sees just about the same numbers.
 
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I won't try to turn you off of the Corvair if building your own engine is one of the end-goals. There's lots of builder support, and its a neat way to have your hands on every part of the project. That being said, there's nothing stopping you from re-building your own Lycoming and sticking it on a 7 or 9. I did that for my latest build, and found it just as rewarding. There were several shops that even offered me the option of coming and working with their engine guy looking over my shoulder.
 
I strongly considered a -7 for my first build, but then realized how big of a project it really is. I'd rather build something quicker and easier, less time not being with my 4 year old son, which he could start helping with In a few years.
 
I strongly considered a -7 for my first build, but then realized how big of a project it really is. I'd rather build something quicker and easier, less time not being with my 4 year old son, which he could start helping with In a few years.

Even if you choose to use an engine package (Viking, etc.), doing an alternative engine install in the RV-12 is automatically adding a lot more time to the build than you would likely ever imagine, so this choice will act directly against your goal.
 
In case you are interested, I have a friend who has built a very nice Corvair engine for his Turner project, but has come across an 0320 to use instead,
so the Corvair is for sale.

I've been searching for first plane project, RV-12 is at the top of that list. The #2 plane at the moment, is the Zenith CH-650, very similar in many ways.

One of the draws to the Zenith, was the ability to use the Corvair engine.

I really like most things about the -12, except the cost of the 912S.

The Corvair is a little heavier than the 912, about 35lbs. I know there are some -12s flying with the Viking engine, which is about the same weight as the Corvair.

I'm not concerned about being LSA compliant, it'll be built E-AB.

Is anyone aware of a -12 being built with a Corvair powerplant?

The -12 is very economical, built not much cheaper to build than a -7, my #3 choice. I can build a 100hp Corvair engine for about $6k, plus engine mount, prop, etc.

Thoughts?
 
The Corvair is a little heavier than the 912, about 35lbs. I know there are some -12s flying with the Viking engine, which is about the same weight as the Corvair.
You know, I've looked and looked, and never seen anything indicating specifically what a Corvair engine converted and ready to fly actually weighs. I read a long-ish blog post from WW about it, and that STILL didn't mention a specific weight, just claimed that it was "about the same as an O-200" or words to that effect. Have you seen something documenting actual weights for Corvair engines? I'm just curious. For power to weight ratio it's tough to beat a Rotax 912, but they are certainly priced accordingly.

CG on the RV-12 would seem to be a likely place to run into trouble, since I suspect the Corvair engine is longer than the 912 and probably has more of its weight farther forward. If the intent is to keep it LSA qualified, you're eating into your useful load with the extra weight. if LSA is not a factor, it seems the RV-9 might be a better candidate but of course it would take a lot more time and effort.

Just my random thoughts on the subject, feel free to ignore.
 
Definitely appreciate all the responses and opinions.

I wanted to build a "simple" plane as my first, hence the -12. I'm getting my PPL currently, so LSA is not required.

I'll probably design my own basic VFR panel anyway, so I'm already signing up for additional work, and it's a challenge that I like.

From FlyCorvair.com:
"The engine weighs 225 pounds ready to run. This is effectively the same as a Continental O-200. It?s installed weight is 35 pounds more than a 912 Rotax, 25 pounds more than a Jabaru 3300. The Corvair is 40 pounds lighter than a Lycoming O-235. 3,000 cc Corvairs are slightly lighter than 225 lbs. because we have special cylinders made for them which make these engine 5 pounds lighter."
 
Another factor to consider, I am aware of 5 Zenith 601/650 flying with Corvair, zero RV12. Getting the W&B plus engine mount and cowling would be much simpler on the Zenith.
 
Another factor to consider, I am aware of 5 Zenith 601/650 flying with Corvair, zero RV12. Getting the W&B plus engine mount and cowling would be much simpler on the Zenith.

Actually, I think there are over 30, maybe many more than that.

I think I'll ask about W&B over on the Zenith forums. The CH650 is designed to run a 912, Jabiru 3300, O-200, O-235, etc, I wonder how they address huge differences in engine weights.
 
I am sure you are right, I just meant ones I have seen and spoke to the owner.
Worthy of note, each owner was very happy with the Corvair.

QUOTE=E28POWER;1220109]Actually, I think there are over 30, maybe many more than that.

I think I'll ask about W&B over on the Zenith forums. The CH650 is designed to run a 912, Jabiru 3300, O-200, O-235, etc, I wonder how they address huge differences in engine weights.[/QUOTE]
 
Different length engine mounts. Those UL-Power's stick way out there. It works because the pilot/passenger sit behind the center of lift and the engine can be used to leverage their weight. If I'm not mistaken, on the RV12 the pilot/passenger are in front of the center of lift which means that the only way to accommodate a heavier engine is to make a SHORTER engine mount than the one designed around the Rotax. Not quite sure if that can be done.... WW has made mounts for a bunch of different airframes and would probably be the one to talk to about designing and making one for the 12. You'd want to get your order in early though (possibly even several years in advance) as it would be a lot of work and he tends to be backlogged.

As for ease of building, my 601 was not pre-punched, but easy enough for a first build. The newer ones go together much faster. Don't know how the build difficulty compares between the 6xx series and the RV12, but having seen both side-by-side, the 12 is the better design hands down (which, of course, you pay more for).

The above posts are definitely right in that designing your own electrical system and FWF layout takes almost as much time as the airframe build. It is fun, and is a different type of work than you will have been doing on the airframe which is nice.
 
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Definitely appreciate all the responses and opinions.

I wanted to build a "simple" plane as my first, hence the -12. I'm getting my PPL currently, so LSA is not required.

I'll probably design my own basic VFR panel anyway, so I'm already signing up for additional work, and it's a challenge that I like.

From FlyCorvair.com:
"The engine weighs 225 pounds ready to run. This is effectively the same as a Continental O-200. It?s installed weight is 35 pounds more than a 912 Rotax, 25 pounds more than a Jabaru 3300. The Corvair is 40 pounds lighter than a Lycoming O-235. 3,000 cc Corvairs are slightly lighter than 225 lbs. because we have special cylinders made for them which make these engine 5 pounds lighter."

Not sure where you got the Rotax weight # but it is a bit on the high side.
Installed weight for a 912 is closer to 170 Lb so that would put the Corvair 55 lbs heavier. That would be rather difficult to deal with.
At least one RV-12 was built with an O-200 and once the builder got to the weighing and C.G. calculation process, he ended up removing it and installing a Rotax.
 
I would not recommend a Corvair engine for the RV-12 with the weight and length issues you will have to deal with. I installed the Viking 110 and it added two years to my build time not to mention 50 extra pounds over a typical 912 powered RV-12 empty weight. Forward CG issues required moving the dual batteries and dual fuel pumps behind the baggage compartment bulkhead to get weight off the nose wheel.

If I were starting an EAB RV-12 today and wanted to do my own engine package, I would look for a used 912 ULS ($6K-$9K) to build up with an EFI and maybe a performance camshaft for a few more HP. If you want a Corvair powered aircraft, scratch the RV-12 off the list.

John Salak
RV-12 N896HS
 
I agree

I would look for a used 912 ULS ($6K-$9K) to build up with an EFI and maybe a performance camshaft for a few more HP. If you want a Corvair powered aircraft, scratch the RV-12 off the list.

John Salak
RV-12 N896HS

Well said. As someone who built a 601 with a Corvair engine, I can tell you that the engine runs fine, but it does leave the airplane nose heavy.

I?m with John that a used engine is probably a better choice. I bought a used UL 350iS for less than 1/2 new price.
 
All good, valid advice that I will use. Thank you all, looks like a Rotax is in my future.

Now, to decide between trying to find an abandoned gen 1 RV-12 kit, or just go for a RV-12iS kit. I live 45 min from Vans, so that's convenient.

Decisions.....
 
Why not use a VW engine light cheap lots flying in Sonex aircraft.

Not enough power, the Sonex has a 1100lb gross weight with the VW. It might be doable, but there isn't enough safety margin for me. It would be a single seater in the summer.
 
You stated that ?simple? is important. Trying to fit anything other than a 912 would certainly change simple to complicated fast!
 
I'd rather build something quicker and easier, less time not being with my 4 year old son, which he could start helping with In a few years.

If you finish the plane one day you'll want to take your son flying with you. :)

On that basis I wouldn't be making engine purchase decisions working backwards from a desire to save money. I'd be making that decision based purely on the most reliable product available. And in the case of the RV12 that happens to be the Rotax provided by Vans. ;)
 
I am not sure if your are talking about a Corvair with a reduction drive or direct drive. If direct drive, remember the corvair’s thrust bearing is at the back of the motor and was not designed to carry a prop, just a flywheel. The crank is not counter balance and is designed to have a flexible coupling. Please think of the others who will be trusting you to build a safe plane.

Most Corvairs are flying direct drive with a 5th bearing to handle prop loads. Many are flying with alloy steel billet cranks as well. They work just fine in aircraft these days using a fairly proven recipe based on hard lessons from the past.

Hard as it may be for some to understand, some folks want something different than another cookie cutter RVX. Power to the true experimenter- as long as they understand the extra work and possible risk involved. Most people who go with the tried and true will never feel the satisfaction of making something different work well.
 
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I gave up on the idea

We contemplated using a Corvair on a 12 but after thinking about it for a long time I just felt that the weigh difference wouldn't work out. I like the concept of the Corvair because I felt that it is closer to design of the Lycoming O320 I have in my 9A and it would be direct drive. If you try to build up a Corvair to the level that Dan of Panther fame has in his 3300 then you are going to be pushing around $17000 if you use his and WW components. I have two Corvair cores which I acquired when thinking of building a Zenith 650 before my brother acquired the 12 kit.
 
Safety is a top priority for me. I liked the Corvair partly because it has a great safety record. Most of the few failures were in engines that were built differently than WW suggests.

Can't ignore the safety record of the Rotax. Plus, there are big bore kits if I need more power(probably not).

I will be taking the advice given here. Before this thread, I couldn't find any good reasons not to put a Corvair into an RV-12. Anything I found basically said "Vans wouldn't approve of that", or "it's perfect, why change it". But, the later responses were great and valid reasons.

Thank you.
 
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