Introduction

[oikuanwsfreui]

My name is Todd, I currently own and fly a PA-28-140. I've always been drawn to the experimental side of things since I grew up turning wrenches, but impatience got the best of me when a good deal presented itself. I'm now in the planning stage of starting a new build. Currently leaning toward a Corvair-powered Sonex-B.

 

[Rhino]

Welcome!

 

[Vigilant1]

I'm now in the planning stage of starting a new build. Currently leaning toward a Corvair-powered Sonex-B.

Welcome. I own a VW-powered trigear "Sonex A" built by an owner/builder in Texas. A member here ("Daleandee") built and flies a very nice Corvair-powered Sonex A taildragger.

 

[Daleandee]

A member here ("Daleandee") built and flies a very nice Corvair-powered Sonex A taildragger.

I'll echo his welcome and admit to owning a Corvair powered taildragger. Latest video is here:



Just a heads up on your plans ... as far as I know no one is presently manufacturing a Corvair mount for the B airframes. The A model airframe engine mounts are available through Dan Weseman at SPA.

 

[oikuanwsfreui]

I'll echo his welcome and admit to owning a Corvair powered taildragger. Latest video is here:



Just a heads up on your plans ... as far as I know no one is presently manufacturing a Corvair mount for the B airframes. The A model airframe engine mounts are available through Dan Weseman at SPA.

Interesting. Thanks for the heads up on the engine mount. I actually watched the of your videos today. That's a beautiful plane you've got!

 

[Daleandee]

Interesting. Thanks for the heads up on the engine mount. I actually watched the of your videos today. That's a beautiful plane you've got!

I've spoken with several builders that wanted to use a Corvair on the new B model if a mount were available.

If my lottery tickets ever have the correct numbers I may consider building a Sonex high wing but more likely the Bearhawk LSA. Whichever it is would be Corvair powered. There's already a Corvair powered Bearhawk LSA that is finished and flying:



Thanks for the kind comments on the plane.

 

[oikuanwsfreui]

I've spoken with several builders that wanted to use a Corvair on the new B model if a mount were available.

If my lottery tickets ever have the correct numbers I may consider building a Sonex high wing but more likely the Bearhawk LSA. Whichever it is would be Corvair powered. There's already a Corvair powered Bearhawk LSA that is finished and flying:

View attachment 120751

Thanks for the kind comments on the plane.

I suppose I'll have to look into a potential custom motor mount when/if I move forward with a B model. I'm curious though if you don't mind, what sort of weight and balance issues have you run into with your Corvair/Sonex combo? I've heard vague rumblings about weight and balance being an issue but haven't been able to find any details.

 

[cluttonfred]

I suppose I'll have to look into a potential custom motor mount when/if I move forward with a B model. I'm curious though if you don't mind, what sort of weight and balance issues have you run into with your Corvair/Sonex combo? I've heard vague rumblings about weight and balance being an issue but haven't been able to find any details.

Welcome, Todd!

If there really is a community of builders out there looking to put a Corvair in a Sonex B then you might be able to do a group buy of mounts or maybe build the jig and rent it out to other builders who need it.

 

[Daleandee]

I suppose I'll have to look into a potential custom motor mount when/if I move forward with a B model. I'm curious though if you don't mind, what sort of weight and balance issues have you run into with your Corvair/Sonex combo? I've heard vague rumblings about weight and balance being an issue but haven't been able to find any details.

I'd be interested in the "vague rumblings" that are out there.

As far as weight .. the Corvair is heavy. It's a bit lighter than an O-200 but the factory is not happy about the use of them. But mine has been extremely reliable, smooth, and makes great power. There certainly are heavier choices that have been used on this airframe but I digress.

The CG on my plane is excellent. I did mount the battery in the tail to counter the heavier FWF weight. My current CG requires a single pilot with full fuel & no baggage to be at least 180 lbs. But with it set up this way there is no loading scenario that puts the CG close to or over the rear limit (obvioulsy respecting the gross limit of the plane). If a pilot of less than 180 lbs. were to fly the plane the CG would have to be changed by adding weight to the pilot seat, adding luggage, or not filling the fuel tank.

Dunno if this helps ...

 

[oikuanwsfreui]

I'd be interested in the "vague rumblings" that are out there.

As far as weight .. the Corvair is heavy. It's a bit lighter than an O-200 but the factory is not happy about the use of them. But mine has been extremely reliable, smooth, and makes great power. There certainly are heavier choices that have been used on this airframe but I digress.

The CG on my plane is excellent. I did mount the battery in the tail to counter the heavier FWF weight. My current CG requires a single pilot with full fuel & no baggage to be at least 180 lbs. But with it set up this way there is no loading scenario that puts the CG close to or over the rear limit (obvioulsy respecting the gross limit of the plane). If a pilot of less than 180 lbs. were to fly the plane the CG would have to be changed by adding weight to the pilot seat, adding luggage, or not filling the fuel tank.

Dunno if this helps ...

That helps immensely. Thank you. That is certainly a tradeoff I'd find acceptable in terms of weight and balance. As to vague rumblings, This interview w/ Mark Schaible at Sonex talks about W&B tradeoffs with the Corvair engine, but offers no details about what those tradeoffs might be. Ran into a few forum posts here and there along the same lines, but no details. Thanks again!

 

[Daleandee]

This interview w/ Mark Schaible at Sonex talks about W&B tradeoffs with the Corvair engine, but offers no details about what those tradeoffs might be.

I like Mark and have no desire to get into a spitting contest with him or anyone else over what they state concerning their airframes. He certainly seems to have a much better approach to heavier conversion engines being used on the airframe than John ever did.

I miss Jeremy terribly because he was a great guy and also helped Sonex to take a softer approach towards alternative engines. He had expressed to me a few years before his untimely demise the desire of Sonex to find better/other engine choices for their airframes. At that time the Rotax 9-series were forbidden as not being "simple" enough even though they were well under the FWF weight limit. They are now allowed. Other changes have come over the years because builders desired them and made them work i.e. hydraulic brakes, electric flaps, more powerful engines, etc.

I wrote a series of posts on the Sonex Builders site that tells of the process of evaluating, choosing, and finally installing the Corvair engine on this airframe. It was in response to John asking what "justification" anyone could have for doing such a thing. I asked the mods (offline) if I could politely respond and they allowed the conversation to happen. It got heated at times but ultimately a lot of good information was gleaned about this combination and its continued success.

Mods: Sorry ... no intent to hijack the thread.