SonexBuilders.net

I have flown my aerovee powered sonex very little over the past year and a half and have been thinking about why. A lot of it is just not having enough free time but another big part of it is the motor mounted on the front end. I went with the aerovee because that was what I could afford at the time, I was familiar with aircooled VW auto engines, and it had good factory support. The problem is that since building and flying I now know a few people personally involved in accidents (one fatal) who where flying behind an aerovee that decided to stop turning at inopportune times. That coupled with a very anemic climb rate with two on board during the summer gets the pucker factor a little too high to be fun for me anymore. To be fair I have flown my plane for around 100 hours including a trip at gross weight back and forth from Connecticut to Oshkosh. It hasn't given me any reason to consider it unreliable and I know many people have flown the aerovee for hundreds of hours trouble free. I thought about selling the plane and building something like an RV but when I contemplate it I realize that I have full faith in the airframe, just not enough in the engine. Almost all the airports here in Connecticut are surrounded by trees and hills so something with a better climb rate to get me more quickly to an altitude where I am comfortable with may be a better solution than starting over with a new plane.

I have started looking around and the corvair is a strong possibility as there are now quite a few flying in the sonex airframe. UL, and rotax are out of my price range and the Jabiru/Cammit engines look like they may or may not have spare part supply issues in the future. The turbo aerovee was considered for a while and although it would probably help some with the climb rate it won't help with the (probably illogical fears) of reliability. So I have a few questions on the corvairs that maybe some of the cleanex builders might be able to answer.

1) Performance numbers - What are you seeing for climb rate at sea level or a normal 80 degree day around 1200lbs? How about cruise speed and GPH? I'm just looking for rough numbers.

2) Are there any builders in the northeast that have an installed corvair and wouldn't mine me taking a drive to come see their plane?

3) Any really good documented build sites for a corvair powered sonex?

4) Could you estimate the total cost of building and installing a corvair assuming you are starting with a blank firewall and doing all the assembly work yourself.

5) What do you consider to be the weak points of the corvair?


I'm sure I'll have more questions the more I research, just figured I would start here. I know the corvair is a little bit taboo with the factory so if you would prefer to not post on the forum feel free to PM or e-mail me.

Thanks,

Keith
Sonex #554

kmacht wrote:I know the Corvair is a little bit taboo with the factory ...

Keith
Sonex #554

8~)

PM sent

Dale Williams
N319WF @ 6J2
Myunn - "daughter of Cleanex"
120 HP - 3.0 Corvair
Tail Wheel - Center Stick
Signature Finish 2200 Paint Job
166.7 hours / Status - Flying
Member # 109 - Florida Sonex Association

Hi Keith

I’m on Long Island, building my Waiex. Can’t give you a flight report, thats a ways away, but my motor is ready to go, installed in the coffee table for the time being. Have also the motor mount, nosebowl, baffles, intakes and exhaust, most of the firewall forward that you can get from WW. The process with WW took awhile, but he has teamed up with Dan Weseman of Panther and streamlined the process hugely. Happy to talk if you want, or show amd tell if you want to visit.

Best of luck, Gordon

I'm curious, why do you think the Corvair would be more reliable than the VW? If it's just that you don't personally know anyone who's had an accident using one, that doesn't seem like a rational reason.

I think it's very difficult to know both the true fault rates and the causes of engine problems in experimentals. There is no accounting of how many hours in use different setups have, many conversions are assembled by the builder, and most installs are unique in one way or another. One engine might run forever and another had a catastrophic failure. Is this due to assembly error, different setups, or just random chance? I think one has to come to terms with this uncertainty if operating an experimental. Only certified airplanes that are virtual clones have a hope of accumulating statistics on this, and even there many problems are maintenance-induced, as Mike Busch constantly points out.

I think we could pretty much assume just via these forums that the aerovee requires some what more tinkering than the jaburu to keep going well. That being just in the Sonex airframe for example.

lutorm wrote:I'm curious, why do you think the Corvair would be more reliable than the VW?.

As I said, my aerovee has performed fine but I have reservations about it. Two aerovee factory aircraft which should be the pillar of reliability have crashed on takeoff without a good explanation as to why. I know another person who died from what was most likely engine issues. I'm not saying the corvair is more reliable but in my opinion it looks better on paper. I know the aerovee works as there are plenty flying and I'm not here to argue with you over that fact I just want something that is better for me.

If you assume that the corvair and aerovee are both equal in reliability there are still other factors to consider. Here in the northeast almost every airport is surrounded by trees with very few option if the engine quits on takeoff. The quicker I can get to altitude the more options I have. With an aerovee powered sonex and two normal sized people and full fuel on an 80 degree summer day I'm only seeing 250 feet per minute. It appears that a corvair would vastly improve that number. The trade off is fuel burn. Most of my flights last an hour or less buzzing around the local area so that isn't a concern for me.

I would prefer this thread not turn into a aerovee reliability debate. I really am looking for corvair info here. I'm willing to discuss specific concerns I have about the aerovee if someone wants to start another thread but the notes above are all I'm going to say about it here.

Keith
#554

I too am interested in the same information requested. I have a Corvair core and leaning towards that power plant. I have the Aerovee mount and cowling ready to go, just think I want more horsepower for climb performance.

kmacht wrote:It appears that a corvair would vastly improve that number.

No arguments there. In fact, the "How to Hot Rod your Volkswagen" suggests that a good way to get affordable and reliable high power is to swap out the engine for a Corvair. :-)

GordonTurner wrote:Hi Keith

I’m on Long Island, building my Waiex. Can’t give you a flight report, thats a ways away, but my motor is ready to go, installed in the coffee table for the time being. Have also the motor mount, nosebowl, baffles, intakes and exhaust, most of the firewall forward that you can get from WW. The process with WW took awhile, but he has teamed up with Dan Weseman of Panther and streamlined the process hugely. Happy to talk if you want, or show amd tell if you want to visit.

Best of luck, Gordon

Gordon,

Thanks for the offer. I may take you up on a visit once I decide to pull the trigger. Did you build up your corvair with the WW manual or did you buy it complete?

Keith
#554

The major difference between the VW and the Corvair is the heads. The Corvair‘s heads were designed for very high heat dissipation.