Corvair power for Panther and Sonex reference page


I have collected in this one story a complete overview of the Corvair power option for builders considering or working on the SPA Panther kit aircraft and Sonex airframes.  These two aircraft are grouped together because both of these installations were developed by Dan Weseman, (SPA is his company) who offers airframe components that seamlessly work with our Corvair engine components.

Builders who are already working on, or flying a Corvair will be familiar with much of this material, but I bring it all together here for Panther and Sonex builders who are not yet familiar with the Corvair. If you would like to start with a simple three page spec sheet on the engine, read this link first: Basic Corvair information



Above, Oshkosh 2013: Dan Weseman selected the Corvair as the engine for his Panther prototype. He did not make the choice lightly. He has hundreds of hours of Corvair flight experience, developed the highly successful “Cleanex” (Corvair powered Sonex airframe combo), manufactures a number of Corvair flight products like 5th bearings and Billet Cranks, and is well known and respected in the Corvair movement. In 2009, we awarded him The Cherry Grove Trophy , as Corvair Aviator of the year.


The Panther:

The Panther was designed to take a very broad variety of engines from large VW’s to 160hp Lycomings. Dan has extensive flight and ownership experience with most Common light aircraft engines, but he selected the Corvair as his chosen introduction engine for the Panther for a number of good reasons. Not only is the engine powerful, smooth and reliable, it also supports Dan’s mission of keeping the plane affordable for rank and file homebuilders.

No rational man introduces a new aircraft with an engine he must make excuses for. Dan knew the Corvair would not disappoint the industry people and media who would be invited to fly the prototype. The most common thing said by highly experienced builders and designers who see the Panther perform 170 mph low passes, 1600 fpm climbs and aerobatic maneuvers is “I can’t believe that is powered by a car engine.” The Corvair in this installation has the performance to change aviators perspectives on the capabilities of auto conversion engines. Paul Dye, Editor in chief of Kitplanes, came to Florida to fly the plane. Very impressed, on the engine he commented that it functioned just like a Lycoming, just much smoother.

Above, Paul Dye, editor of Kitplanes returns from his flight in the Panther.


If you would like to see a visual example of how well the plane performs with a Corvair, get a look at this link:–ZQVI


You can read all the detailed information on the SPA website at this link:



If would like to read about how this airframe flight tested Billet Cranks Made In The USA, click on the story title.


Above, enroute to Corvair College #16, ‘Son of Cleanex’ builder/pilot Chris Smith shot this photo of Dan Weseman off his wing as they flew up from Florida in loose formation. Although it is not for everyone, the Corvair when installed correctly in the Sonex airframe provided a high performance engine that is essentially immune to overheating issues.


The Sonex:


The Sonex is an outstanding light aircraft designed by John Monnett. It, and the Y-tailed Waiex have sold hundreds of aircraft kits. For 10 years,the Sonex factory approved only three engines for the airframe: the 2,180cc VW, and the 80 hp and 120 hp Jabbirus. The factory position firmly asserted that for an aircraft to be a Sonex, it must have one of these three engines. We’re personal friends with the Monnett family, and to respect their wishes, I carefully referred to the combination as a Corvair powered Sonex airframe, or Dan’s development as a “Cleanex” (a name Dan was slow to grow fond of.) I picked the name because Dan’s plane was a very clean build, that most people were stunned to find out was plans built, not a kit.

Recently in an EAA Webinar, Jeremy Monnett announced an company policy change of sorts, and stated that they were going to adopt a much softer line on this, comparative to other experimental airframe companies. Even with this change, we still refer to any Corvair powered Sonex or Waiex airframe that is adapted to Dan’s installation and uses our engine parts as a “Cleanex.” Like 1950’s Frankenstein movie sequels, a number of builders chose names for their planes like “Son of Cleanex”, “Bride of Cleanex” and “Daughter of Cleanex.”

Dan’s plane is an outstanding performer. I flew in it with Dan, on an 85 degree day off  our 2,400′  tree-lined grass airstrip in Florida. At the time our combined weight was 430 pounds and we had 12 gallons in the tank. If anyone tells you that VW’s are as powerful as Corvairs, they simply have never seen a Corvair in action. Dan’s plane could do an honest 155 mph on 5 gallon’s an hour, and top out above 175 mph.  Dan demonstrated many times that he could run the plane flat out at top speed for more than 40 minutes without the engine running hot.

I offered an opinionated Jabaru 3300 pilot $1,000 cash if his plane could beat Dan’s over a 100 mile course.  He didn’t take me up on it for a simple reason: he was afraid if he ran his $18K engine that hard for 40 minutes he would cook it. The speed would have required running the Jabaru 500 rpm over its factory approved continuous rating. GM designed the Corvair with a 5,500 rpm redline and a 575F CHT limit. Even at top speed, Dan’s Corvair is only using a fraction of these ratings. The is the key element in the Corvair’s reputation as a very robust power plant. It is approximately 25 pounds heavier than a 3300; much of the weight difference is in the Corvair’s cylinder heads which are literally covered in deep cooling fins.

If you would like to see for 120hp Corvairs taking off in succession, check out this link. Dan’s and Chris Smiths aircraft are two of the planes leaving Corvair College #16:



Above, Dan and his Cleanex in front of my hangar at Corvair College #8. (2004) Until his airplane was done and flying, we kept Dan’s identity a mystery. At the time, a few people who saw this photo made jokes about the “Builder Protection Program” with a nod toward John Monnett’s allegededly sharp temper about people putting other engines in his designs. In reality, Dan is friends with the Monnetts.  The Cigarette was part of the ploy, Dan has never been a smoker. Today, Sonex ltd. has a much more relaxed attitude about alternative engines.

In the above photo is from sun n Fun 2012, eight years later. Building a “cleanex” has a fun side also, where builders like to keep ‘traditions.’ From our 2012 SnF coverage, a picture and a comment that pre-dates the policy change by the Monnetts: “A Sonex builder next to Dan. We are having a good laugh disguising his identity because on his shoulder is a motor mount that mates the Sonex airframe to a Corvair engine, creating a “Cleanex.” Here we are kidding around about the  man in the yellow shirt entering “The Builder Identity Protection Program” because the combination is not approved by John Monnett, the airframe’s designer. In years past, John was known for having low tolerance for people modifying his excellent airframe designs. Truthfully, I know him fairly well and he really doesn’t get that upset about it as long as builders choosing other engines do not level unfair criticism at his selected engines.  There are now about 10 Cleanexes flying, and Dan is glad to work with any builder who has chosen the combination as long as they respectfully avoid Internet comments that would raise John Monnett’s blood pressure.


Many people have seen Dan and Grace flying aerobatics in “The Wicked Cleanex” on our Corvair Flyer #1 DVD. Continuous use of this type of operation led Dan to independently develop his own simple, retrofitable fifth bearing setup to reduce flight loads on the Corvair’s crankshaft. You can read about it on his website While people just getting into aviation occasionally view Dan’s flying as daring, I want to emphasize that it is a smooth display of skill and has nothing to do with daring or risk taking. I’ve gotten to know him pretty well, and around airplanes, Dan is pretty conservative. I would easily name him the steadiest pilot and most meticulous maintenance guy in the land of Corvairs.


Above is an early (2006) view of the Cleanex engine. Our Gold Hub and Front Starter system are clearly visible in the photo. Note that all of the engines we build have Lycoming style starter ring gears on the prop end of the engine. All of Dan’s installations use our arrangement. In the past, a handful of homebuilders and here today, gone tomorrow outfits put the ring gear on the firewall end of the Corvair. On a Sonex airframe, it is a critical that no builder operate with such a location because it puts the exposed, spinning, ring gear very close to the Sonex’s plastic fuel filler neck, which could lead to a disaster in an otherwise minor accident. To fly a ‘rear starter’ in a Sonex airframe is foolish, to promote it would be amoral.


The combination of the Sonex airframe and the Corvair proved very sucessful because Dan wisely chose a mixture of our proven parts and systems, clever craftsmanship and practical hot rodding.  Once Dan showed people what the plane was capable of, it was more frequently called “The Wicked Cleanex.”  Over time the plane served as a test bed for a number of  our parts like the Gold Prop hub and the reverse gold oil filter housing. Dan used it to prove out his popular 5th bearing system. You can read more of the story of the airplane at Dan’s Web site,


Our approach to serving builders is different than typical businesses geared only to sell things to consumers. Our goal is to assist you on your path to becoming a more skilled aviator. The products we sell support this, but simply getting you to buy things is not what I am in aviation to accomplish.



This page is broken into the following sections:


1) Introduction

2) Engine and build options

3) installation components

4) Support for builders

5) Flying Panther and Cleanex info.

6) Builders in process

7) flight data and safety notes

8) who is WW?

9) Comments on dangerous trash.


At the end of each section there are links to supporting stories that have expanded information on concepts discussed in the section. Take your time and study it carefully.

I will be glad to answer further questions just email or call 904-529-0006. You can also check our two websites, , . The first is our ‘newspaper’ the second is our ‘library’ and ‘store.’ The links below are stories that already appear on these two sites, they are just arranged here to support this introduction to Corvair power for Panther and Cleanex builders. For installation components in section four, contact Dan and Rachel directly.


In the foreground above is Dan Weseman’s Wicked Cleanex. Off his wing, Chris Smith flies the Son Of Cleanex. The photo was taken over a bend in the St. Johns River in North Florida.


1) Introduction:

The Corvair has been flying since 1960, and I have been working with them as flight engines since 1989. It is a story of careful development and testing, a slow evolution to the engines we have today. It is ‘old and proven’ rather than ‘new and exciting.’  If that approach appeals to you, read on. There is a lot of material here, and it isn’t something you are going to absorb in one quick scan. Frankly, your engine selection deserves careful consideration, and it isn’t the kind of decision you should make based on a 4 page sales brochure.

Corvairs have proven themselves to serve a very broad variety of builders. Many alternative engine options are offered only as a “buy it in a box” import, more of an appliance than a machine, with little or no consideration of the builders, skills goals, needs, budget or time line. The Corvair has options to address these valid considerations, because your power plant should conform to you, not the other way around.

This said, Corvairs are not for everyone.  In the 25 years I have been in the EAA and working with builders, the Corvair has always been very popular with ‘traditional homebuilders’, the people who have come to experimental aviation to discover how much they can learn, understand and master.  The expansion of the EAA has brought more of these builders, but it has also brought a great number of people incapable of distinguishing between mastery of an aircraft or an engine and just merely being its buyer and owner.  People who’s consumer mentality and short attention spans are better suited to toy ownership than mastery of skills and tools in aviation. Corvairs, and perhaps experimental aviation, are a poor match for such people. Many salesmen in our field will gladly sell anything to anyone with green money. I am an aviator, not a salesman, and the gravity of the subject requires more frank discussion and ethics than many salesmen bring to the table.

If you came to experimental aviation to find out how much you can master, not how little, then you are among the aviators who follow Lindbergh’s timeless 1927 quote: “Science, freedom, beauty, adventure: what more could you ask of life? Aviation combined all the elements I loved.”  Even if you are brand new to aviation, I am glad to work with you. I have a long history of working with builders of all skill levels. We have a number of successful builders out flying their Zeniths who are the masters of both their airframes and engines, who had never changed the oil in a car before building their plane.  If you got into experimental aviation just to buy stuff, then any salesman will do just fine for you. If you got into experimental aviation to learn, develop your own skills and craftsmanship and make things with your own hands, then who you work with really matters. You can’t become and old school homebuilder / motor head by buying things from salesmen. They have nothing to teach you. What you will do in experimental aviation is not limited by what you already know. It is only limited by what you are willing to learn, and selecting experienced people to learn from.  If you are here to learn, I am here to teach. It is that simple.



a) – Complete Lindbergh quote is here: The Quote, 1927, C.A.L.

b) – Explanation of machines vs appliances : Machines vs Appliances Part #2

c) – Story of real engines vs ‘ideal’ ones: Unicorns vs Ponies.

d) – A direct explanation of what makes my work different: 2011 Outlook & Philosophy

e) – A moving statement of philosophy: Sterling Hayden – Philosophy



Above, a 3,000 cc Corvair, The actual engine in the Panther Prototype.  The Corvair is an inherently simple engine, It’s opposed six configuration makes it the smoothest of available power plants. It has outstanding cooling because GM put a tremendous amount of cooling fins on it and  gave it a factory CHT redline of 575F. All of our engine parts are made in the United States, as are the airframe parts from SPA.


2) Engine and build options:


If you are new to Corvairs, lets quickly cover some ground: General  Motors made 1.8 million Corvairs. brand new parts, including billet cranks, forged pistons, valves bearings,  virtually every single part inside is currently made and readily available, and will remain so. Rebuildable Corvair engines are plentiful, and much easier to find that Lycomings or Continentals. We have been working with Corvairs for 25 years, and there is no shortage of core engines or parts. If you doubt this for a second, Google “Corvair engine parts.”

The Corvair makes an outstanding aircraft engine because it is a simple, compact, direct drive, horizontally opposed six cylinder, air cooled engine. It is robust, and ‘flat rated ‘ from it’s automotive output. The engine runs equally well on automotive fuel and 100LL, and it does not care about ethanol. In its 53 year flight history, more than 500 experimental aircraft have flown on Corvair power.

The engine can be built in three displacements with three respective power outputs. They are 2,700cc / 100HP, 2,850cc / 110HP and 3,000cc / 120HP. The two smaller displacements weigh 230 pounds, the larger actually weighs 8 pounds less because it uses lighter cylinders. All engines are completely rebuilt from very high quality parts before flight. They are not just removed from cars. The parts we use are specifically selected to convert the engine for the rigors of flight use. Forged pistons, Inconel valves, chrome rings, ARP rod bolts and many other components are upgraded in the rebuild.

To absorb the propeller and flight loads a “5th bearing” is added. It is a billet housing with a very large bearing from a V-8, bolted on the end of the case. The ignition is redundant and utilizes two 40,000 volt systems, one driven by digital electronics the size of a match book, the other by a traditional set of points. The engine is direct drive, it has no complex reduction unit. It makes good thrust because it has more than twice the cubic inches of a Rotax 912. All of the systems on the engine are intentionally patterned after those on Lycomings and Continentals, because they are the  model of success in proven aircraft power plants. People who do not acknowledge certified engines as excellent models of success are often just zealots.  To succeed in experimental aviation you need dispassionate information not emotional opinion.

One of the unique features of the Corvair is that it can be built at home, from our information and parts and a locally acquired rebuildable engine, or it can be purchased from us, test run with logs. 90% of current builders are building their own engine at home. Only 10% of the builders opt to have us build their engine. We have happy to serve both builders. In either case, Corvairs are the best match for builders who want to understand and be the master of their engine.

Because of the plans built vs production engine nature of the Corvair, there are large variations in how much builders budgets run. Below is a quick look at the differences. Keep in mind, these budgets are for first class, completely overhauled, zero timed engines with 5th bearings, starting, ignition and charging systems. We have clever builders who have built and flown engines for less than $3,000, but this not representative of main line builders. The numbers below are much better for Zenith builders to budget on.


2,700cc / 100HP typical homebuilders budget: $6,500- Same engine assembled and run from us $9,750

2,850cc / 110HP typical homebuilders budget: $7,500- Same engine assembled and run from us $10,750

3,000cc / 120HP typical homebuilders budget: $8,500- Same engine assembled and run from us $11,750


If you are attracted to the concept of building your own engine, but have not built motors before, Good.  About half of our builders have never built any kind of an engine before. Our main work is teaching people what we know and providing the parts to work with. Our system does not require anyone to be a machinist nor to have previous engine experience.

The procedure of building an engine in your shop follows this format:

1) Get a conversion manual and DVD’s from us, use them to find a rebuild able core engine locally. Disassemble this engine following the steps in the DVD.

2) Send the crank and heads to our approved facilities for rebuilding and modification. They come back ready to ‘bolt on.’ Other parts of the engine are cleaned and inspected. The parts to convert the engine are ordered from us, many of the standard rebuild parts like lifters and gaskets are available from local auto parts stores. We do not ‘middle man’ anything you can directly buy.

3) Assemble these parts according to the manual and DVDs. There is no machine work required, only basic tools are needed, and a few specialty tools like a torque wrench. Many builders attend our free Corvair Colleges and directly learn hands on skills. You can even bring your parts and assemble them under our supervision, and test run your engine on our equipment. College attendance is a plus, but not required. Our methods work without direct training; a good number of engines are built and flown each year by builders who have never met me in person.

4) The test run serves several purposes. We teach people to build one of  three specific models, and we teach them to use specific parts. Not only are these proven, but it also allows me to verify from a remote location that the engine was assembled correctly. A builder can report his static rpm, CHT, oil temp during the test run with his Warp Drive prop at the specified setting, and I can confirm the output and assembly of the engine without seeing it personally.

If you would like a sample of the information on working your way through the above four steps, get a look at this: Getting Started in 2013, part #1, Crankshaft process options.

We also have all of the ‘getting started’ series on a single page, at this link: Getting Started Reference page.

I have broken down building a Corvair and installing it on your airframe into 42 “groups”. Part #1 is about  ’Group 1000′ the crankshaft. If you would like to look at every part that goes into a Corvair, along with the conversion parts we sell, look at Groups 1000 -3300 at this link to our catalog:

If you would like to read above the value of proven engines, read: Why Not the Panther engine?

All builders get started with a conversion manual. The first part of the above link is about manuals and DVD’s.  The direct link to the manual is: almost all builders looking for a rebuild able engine also order the Disassembly  DVD, which covers core engine selection visually. The direct link to it is: We encourage everyone to get started with information, even if you are pretty sure you would like to purchase a production engine from us. If you eventually buy an engine from us, we directly reduce the price to rebate all the money you spent on manuals and DVD’s.



a) – Corvair Weight story: Corvair vs O-200…. weight comparison

b) –  Samples of our production engines:  2012 Corvair Engines For Sale: 100, 110 and 120 HP

c) – For an explanation of ‘flat rating’ and an engine build : Shop perspective: Mastery or ?

d) – A story about engines running on our hangar Dyno:

e) Engine of “Cleanex” builder: World’s Strongest 3,000cc Corvair, built by Greg Crouchley

f) A story about the evolution on 120HP Corvairs: 3,000 vs 3,100 cc Corvair engines.




Above, a 2009 photo from our workshop. I kneel in the workshop next to motor mount Number 100 for the 601 XL.  Most experimental aircraft companies, both large and small, fail because for two simple reasons; First, the ownership cannot physically make the product the sell, and second, their financial backers are unwilling to go several years before seeing the payoff.  Neither of these conditions are true about our business nor SPA/Panther. We are craftsman and homebuilders first, and neither of us has partners nor investors. Few people new to experimental aviation understand that this is key to company stability and longevity, not big size nor flashy promotion.


3) Installation Components for the Panther & “Cleanex”:


Normally we provide every part it takes to install a Corvair in your airframe.  The Panther and the Cleanex are different because Dan developed these specific installations himself.   It is important to understand that these installations work seamlessly with our engine components, and they are custom adaptations of systems that have long been proven to work very well.  In the case of the Sonex airframe, there have been a handful of other people who tried, with poor results, to put a Corvair on that airframe. If you have heard a poor report on a Corvair powered Sonex, it is important to understand not all Corvairs in these airframes are people following Dan’s proven path.

Here’s a 2004 view of the underside of the Cleanex’s motor mount. Dan designed this mount combining the basic geometry of the Sonex airframe’s landing gear attach points and our traditional Corvair bed mount. The structure is well thought out and perfectly triangulated. Although it looks heavy, it is not. It weighs 13.8 pounds, only four pounds heavier than the factory Jabbiru 3,300 mount. Dan’s mount has flown hundreds of aerobatic maneuvers. Dan’s motor mount page is here:


  Being air cooled and carbureted, The Corvair is one of the easiest engines to install. Many companies that are good at selling things are poor at teaching things, like how to install their products. Teaching is the very cornerstone of my work, I am a skilled writer, we run Corvair Colleges, and we have a simple engine. All this adds up to a comparatively easy engine to install. There is no need to rush it, but I can do it working in one long day.

 Installation part numbers are Groups 3400 through 4300 in the second half of our numbering system. Get a look at this link: It contains installation component lists for other Corvair powered airframes, but the list is very similar to the required items for Dan’s installations. The detail items on electrical and fuel systems are identical, and you can review the SPA website for the specific details on the Panther and Cleanex installation components. There are many good photos here:

For the Cleanex, Dan and Rachel offer their own Nose bowls, Cowls, Mounts, baffle kits, Exhausts and intake manifolds. While you are there, get a look at his 5th bearings, rear alternators and Billet Cranks. A sample of their parts page is here:

Dan and Rachel are just in the process of organizing the Panther/Corvair components like the mount, cowl, intake, exhaust and baffling.  You can check the Panther website for up to date information on these parts. If you would like to see the Panther engine runninga prop test, click on this link: Panther
Engine propeller test

Although the Panther is new, the systems are fully tested and well proven. It is important for builders to understand the engine test program went flawlessly because it used custom variations on proven systems. For example, the Panthers exhaust is made from the same materials and processes and uses similar design to the stainless systems we have made for other airframes for more than 10 years. The carburation, intake, cooling and spinner are also variations on long proven themes.

Many people new to building initially think that very economical engines like the Corvair must also be inexpensive to install. In reality, the cost of items like motor mounts and cowls are not affected by the cost of the engine they mount and house.  A mount for a $30K UL-350 and a $7K Corvair have about the same amount to tubing and welding time in them, and thus cost about the same. Most engines have installation kits with exhaust, cowl prop spinner etc, run from $3,000 to $6,000. The Corvair is near the bottom of this range, but the savings of using the Corvair is mostly in the engine, not the cost of installing it.

Above, Chris Smiths plan’e uncowled with Dan’s in the background. A ground run cooling shroud sits atop Chris’s engine. Dan stand on the edge of this 2007 photo I took in his hangar.


a) – For an example of 74 years of aircraft welding talent: Zenith 601/650 Motor mounts, P/N 4201(A) Both Vern and I are friends with Dan and assisted him with some of the welded parts that went into the Panther prototype. Dan is a skilled craftsman and a welder on par with us.

b) – To learn about the Stainless exhausts we make: Stainless Steel Exhaust Systems . These are identical in material and construction to the Panther and Cleanex stainless systems.

c) – Louis Kantor’s 601XL running for the first time in our front yard: The plane is one of more than a hundred  Corvair powered planes that utilize Dan’s 5th bearing. Dan used his Cleanex as the chase plane on this planes first flight.



Above, 2004 at Oshkosh: Next to our personal Corvair powered Zenith N-1777W, I explain our dual ignition arrangement two executives from Falcon insurance, The EAA’s provider. To offer real support, an alternative engine provider must be an effective advocate for his builders on many fronts, including meeting the requirements of underwriters. Just being an engine guru is not nearly enough. Corvair engines that follow our design,  including to ones assembled by builders, are fully insurable at the lowest rates, right from the first flight, because they have an outstanding safety record. Having good effective hands on support is a critical element in this outstanding record.


4) Support for Builders:


Builders selecting a Corvair for their Panther or Cleanex project have an advantage that is hard to overstate; Because Dan and I have been friends for more than 10 years, I am very familiar with both of his installations. I followed his Panther development from the first sketch through the flight test program. While the design can and will be flown on a broad variety of engines, it will be a long time before any other alternative engine provider understands the design and program as well I do.

Many new builders mistakenly believe that they can marry any engine they like to their chosen airframe. In reality, compatibility goes far beyond horsepower ratings and weights. To be successful, it is critical that the engine match the designers perspectives on reliability, risk management and ethics. Differences on these subjects create issues builders can rarely resolve themselves; conversely, having both support teams share the same perspective gives builders strong allies. In 25 years of working with homebuilts I have met many designers and innovators I respect, but my personal perspectives share more common ground with Dan’s than any other person I know in this industry. Please take a moment to read: Panther Roll out.


Beyond the basic engine and installation components, we offer many forms of support to Corvair builders. :


a) We have a flight operations manual with specific test flight plans and procedures: Dan wrote one of the chapters in this manual to share his experience with Corvair builders.


 b) We hold 4 free hands on technical seminars called “Corvair Colleges” every year.  For an introduction to Colleges, read this link:  An overview of upcoming colleges is at this link:  Upcoming events, Airshows and Colleges #26-28. If you would like to see video of a College, here is a link to Corvair College #17 Dan and Rachel attend many of the colleges and were our Co-hosts at Corvair College #23.


c) Woody Harris, subject of this story:  Zenith 601XL-2,850cc, Woody Harris Is our West Coast representative. Although we have held 5 Corvair Colleges in California,  we only make one trip to the west per year. Woody covers all the shows and events from Arlington to Copper State when we can’t be there.


e) I am the last guy in aviation who still makes free house calls. Over the years I have made more than 400 in person visits builders projects. I travel extensively, and go out of my way to include builders workshops on these trips.  These stops and the colleges allow me to really understand the needs, strengths and dreams of rank and file builders that no one can read in email or at an airshow. for a sample, read this story: Corvair House Call, Range: 335 miles.


f)  By my continued advocacy and industry relations, Corvairs have full insurance, at the lowest rates, available from a number of sources. If you would like to find out more Contact Bob Mackey, VP of Falcon insurance, The EAA’s designated provider, seen on the left in the photo above.


g) Over the years, we have built a very tight knit community of like minded builders. If you read this story about fools at our county airport: A visit to the insane asylum, and it sounds like your airport, and if your local EAA chapter is devoid of homebuilders and filled with negative people, you will find the Corvair movement to be a powerful antidote. Many Corvair builders catch several colleges a year, there they find positive, outgoing, energetic builders, effectively making the Colleges their “local EAA chapter” We have worked very hard to attract outstanding people interested in accomplishing their goals. I  go out of my way to encourage new builders but I am intolerant of people who are compulsively negative. I am willing to be a cheerleader, but not a therapist.



Above, Chris Smith’s Cleanex after painting. Chris was building a Sonex airframe from a kit and met Dan as Dan’s airplane neared completion. Chris opted to build a close copy of Dan’s aircraft. Although Chris had many years of flying experience, he had never built an aircraft before. Because of this, he wisely chose to follow Dan’s proven format closely. When Chris’ aircraft was done, it earned the nickname “Son of Cleanex.” It first flew at the end of 2006, and it served Chris through several hundred hours flying over the southeastern United States. Today the aircraft is owned by Ron Monson, who has put a great number of flying videos of it on You-tube.


5) Examples of flying Corvair powered Sonexes:



Above, The Cleanex of Dale Williams taxis out at Corvair Colle #27. Read more on the man and the plane here: New 3,000 cc Cleanex, Dale Williams, SC

Above, Cleanex by Chuck Custer, after flying to Corvair College #25. This aircraft is one of approximately 12 that have flown utilizing Dan’s installation.



Above, Clarence Dunkerley beside his 2850 cc Weseman bearing equipped powerplant destined for his Cleanex project. Sharp eyes will  notice that this is equipped with the Reverse Gold Oil Filter Housing which we developed specifically  for Corvairs going into Sonex airframes. Photo taken at Corvair College#21.


6) Examples of Builders working on this Combination:


Many experimental aircraft companies like to tout how many of their product has sold as a measure of  success. Sales numbers on only a measure of their success, not that of builders. The only number that counts are how many builders that make it all the way to flying and enjoying their creation. It is a fact of marketing that it is far easier to keep finding new buyers to spend money than it is to support the ones that already spent the money, all the way through flight.  This is why many aircraft companies have planned lifespans of only 48 months, so they make all the sales and fold up the tent before they have to do the real work of supporting builders.

We are very different.  I have been working with Corvair builders since 1989. I am in this for the long haul, and my measure of success is getting people flying. Likewise, Dan has been working with Corvairs since 2003, and has been offering parts like his 5th bearing design since 2006.  If you select a Corvair engine, we will be your allies in completing your plane, just as I have been for many others before you.

If your goal is to merely buy something, you need only find a salesman with an engine to sell. If your goal is to learn about, understand, build and fly your plane, you need an instructor-guide-mentor, an aviator not a salesman. Think it over: If your goal was to climb mount Everest, there would be plenty of people you could buy equipment from, but that isn’t the same thing as finding a Sherpa who has been to the top to act as your instructor and guide.  A big part of why experimental aircraft have a 20% completion rate is that most people purchasing a kit or an engine have not spent 3 minutes learning how to differentiate between a salesman and a guide.

Below are a sample of our builders, each of whom I am going to see all the way through their aircraft finished and flying:

Above, Cliff Rose, Cleanex builder from Florida, with his 2700 cc, Weseman bearing, Falcon head engine with Reverse Gold Oil System. Cliff  spared no expense to acquire all the parts of his engine. Still, he spent less than one third the cost of an imported engine. More importantly, he has the well earned  pride of creating his own engine. Photo taken at Corvair College #19.

Above, Aerospace engineer Paul Salter stands beside the Panther prototype. Paul is close friends with Dan and Rachel and has played a significant supporting role in the Panther introduction. He is building Panther beta airframe #2 for himself, and he is already collected most of the parts to assemble his own 3,000cc /120hp Corvair, which will be a direct clone of the Corvair in Dan’s prototype.

Above, Phil Maxson (Left) gets his airworthiness certificate for his 2700cc Corvair powered 601XL from legendary DAR Johnny Murphy, in our old Edgewater hangar in 2006. Today, Phil still flies and enjoys it, but is also well at work on Panther Production kit #1, which will be powered by a 3,000cc Corvair. We awarded Phil The Cherry Grove Trophy for 2013, as Corvair aviator of the year.


Above, Waiex builder Greg Crouchley stands beside me after the test run of his Corvair at our hangar in 2012. Although headed into a Waiex, Greg’s engine is essentially a clone of the Panther’s, including a Weseman billet crank. Read about the man and the engine at this link:World’s Strongest 3,000cc Corvair, built by Greg Crouchley 

If you would like to read a story about and see the film on a running 3,000cc Corvair for a Sonex built at a College, Click on this link: Corvair College #27 run on film. It is the engine of Amit Ganjoo, who is also the builder with the yellow bag over his head in the photo at the beginning of this story.




7) Operational Data for this combination:

Dan and Rachel’s website will be the primary source of performance data for Panther and Cleanex builders. Our website have a continuous flow of discussion on Corvair operations for all types of airframes. If you would like to read a story about detailed flight data collection on a 2,850cc 750, check out this link: CHT part #5, flight data from Zenith 750 . It is an example of the type of information exchanged between our builders.  If you are drawn to aviator’s groups made of intelligent thinking people, you will fit right in with Corvair builders.

Here is a visual example of testing: Panther Engine propeller test

And you can also read a story on operations here: Starting
procedures on Corvairs, 2,000 words of experience.
 Our .net website has more than 375 different stories on it, about 225 of them are purely technical posts with expanded operational information and experience.

I have long stated that I can teach a 12 year old how to assemble an engine, but what we are really trying to share with people is a knowledge base that will effectively allow them to master the engine and use it with good judgment, something a 12 year old (and some adults)  cannot do. If some of the articles that I write don’t initially sound like a set of instructions, consider for a moment that the message of the artice may be about the critical element of Judgment.

If you would like a single example to effectively demonstrate that I am an aviator not a salesman, it is the type of data that I discuss with builders. No salesmen will acknowledge accidents nor difficulties that involved their products, even circumstantially.

Conversely, I am here to teach people what they need to know. I have a long history of writing about subjects that salesmen wouldn’t touch with a 10 foot pole. I write about accidents and friends I have lost, honest mistakes people made and things you can learn from them.  Just about everything know in aviation cost someone dearly to learn. If you are unwilling to talk about these things in plain language, people are doomed to repeat them.


Risk Management, Judgement Error, money in the wrong place. is the story of our only fatal accident in a Corvair powered Zenith. (There is another below, but it was a different company) The NTSB pointed to an incorrectly assembled carb, but read the story and decide if judgment isn’t the root cause.

“If only someone had told him……” is a story about people who don’t listen. Guy A and Guy B were both Zenith 601 builders. Guy B was the passenger in the First 650 accident (AMD airframe- O-200 engine, ruled pilot error). Guy A was a well known and liked Zenith builder and flyer, who quit aviation after this incident.

Risk Management, Factor #1, Judgement. Covers how developing and exercising judgment is paramount to managing your own personal risk.

Risk Management, Experience vs Judgement. Ken Terry was a friend of mine and a huge influence on Grace’s flying, and her development as a pilot. The story is about how experience, even 40,000 hours of it is not a defense compared to exercising good judgment.


Dan Weseman and Dave Dollarhide having a good time at Sun n Fun 2013. They both are in the last story “Friday night” in the link “Three aviation stories”.


 Three Aviation Stories  covers my personal perspective on risk, and what level is worth managing, and how aviators come do deal with this. It speaks of meeting Al Haynes at two points in my life, 14 years and a world of experience apart. It also covers how several members of our EAA chapter each looked at loosing two friends.



Above, A photo taken at Sun n Fun 2006. My wife Grace Ellen and myself, in front of the first Corvair powered Zenith, our own N-1777W. The plane was the first XL model with conventional gear.  Grace is a skilled pilot in her own right. She has been a pilot longer than I have, holds more advanced ratings and owns two aircraft. As a point of ethics, we do not promote, advocate nor sell things we have not personally flown behind.


8) Who is William Wynne?

Modern consumer sales logic dictates that that business should ‘de-personalize’ themselves so consumers find nothing objectionable about the provider while they are spending money.  That model may work elsewhere, and even have advocates experimental aviation, but I don’t buy it.  I contend that Aviation is a different arena, and who you are dealing with, and their ethics, experience and perspective matters.

Building a plane or an engine is a marriage of sorts between the builder and his airframe or engine company. I believe that it is best if everyone goes into it well informed with their eyes wide open. I am always surprised how few people even Google the name of a person they are thinking of working with. You don’t need to see eye to eye with them on every point nor even love them, but the relationship must absolutely have trust and respect operating in both directions. In 25 years I have seen many builders try to justify buying a product from a provider they didn’t really trust. It never works out. It doesn’t matter how good it looks, what it costs or how great it is supposed to work, if it is from a bad guy, it isn’t worth buying.

I could write a quick paragraph about how I am a pilot, a 22 year A&P mechanic, and that I hold both an AS degree in Maintenance and a BS in Professional Aeronautics (accident investigation) From the worlds #1 aeronautical university, Embry-Riddle , but I don’t think that any of that explains my commitment to builders nearly as well as the flying planes of our builders and things we have accomplished. Henry Ford said “A man can not base his reputation on what he says he will do; only what he has done.”

I am plain spoken. to understand why, read the ‘Effective Risk Management’ story below. I have many friends who are experienced aviators who value plain talk. This type of speech also tends to offend people who dabble in aviation and would rather read polite things that align with their pet opinions. I am in aviation to share experience builders need to know, not say things people want to hear. Below are a selection of stories, some humorous, but all with a point, that give people a better understanding of who I am. From there you can decide if you choose to work with me as your engine mentor.


a) Fixing America is going to cost each of us $1.69

b) Greatest Book on Flying Ever Written, (Is your life worth $16?)

c) In defense of plain speaking……

d) Turtles and Cell Phones, 6/24/13.

e) A thought on Easter….

f) Happy Father’s Day William E. Wynne Sr.

g) Effective Risk Management – 2,903 words




9) Notes on trash:

Not all things called a Corvair represent my work or designs. Over the years, our success and willingness to share information has brought out a number of short lived companies that were run by rip off artists, and mentally ill people. Particularly, there have been four businesses that made poor copies of our parts or untested garbage. All of these are bankrupt today. Today, I have just heard that another is coming back with a new name. The story will never end as long as people don’t do their home work or believe that they are getting a bargain. You can read about one of these companies at this link: Cloudn’t have happened to a nicer guy……

I warn people all the time not to buy things from these people, or to buy this stuff at the flymart. For examples of things no one should have bought, look at this story: Built by William Wynne? Built according to The Manual?

Let me be absolutely clear, that I will be polite to people, but I will not work on, offer advice on, or help with products made by bankrupt people that I considered vermin.  Nor will I allow these people to attend any of the Colleges. This isn’t out of spite, it is to protect these builders lives. They all want to put a band aid on their bad purchase and make it “good enough to fly.” A band aid isn’t going to do it, an amputation is in order. People who blew $12K on junk don’t want to hear this, they are still looking for a cheap out that doesn’t exist.  I will not assist them in the delusion that they have found one.

On line discussion groups and websites have a small number of old posts from people who bought trash like this for their projects. If you look closely, these people offered great testimonials, but later abandoned their builds. Look at the dates on many of these posts and then compare them to FAA aircraft registrations on  From looking at our sites you can see photos of dozens and dozens real builders with real names and flying planes. I encourage builders to do their home work; our track record will speak for itself. -ww.


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