Zenith 750 / Corvair reference page, October 2013
October 29, 2013 Leave a comment
Here is a single location page that has a great number of links to information specific to the Zenith 750 / William Wynne-Corvair Combination. It is a particularly good match, we have a number of different ways to approach it that serve the needs of many different builders, and it is a success story that builds on our 10 year history of working with Zenith builders, starting with our own personal 601XL in 2003. Since then we have assisted more than 80 builders to complete and fly their Corvair powered Zeniths. In the coming years these will be accompanied by an ever increasing number of 750’s.
If you already are working on your Corvair, this page will have information you have seen already on our websites, but I have included it so that this page can function as a ‘stand alone’ guide for 750 builders who have just heard about our work with the Corvair. 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. If you would like to start with a simple three page spec sheet on the engine, read this link first: Basic Corvair information
This page is broken into the following sections:
2) Engine and build options
3) installation components
4) Support for builders
5) Flying 750’s
6) Builders in process
7) 750 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 WilliamTCA@aol.com or call 904-529-0006. You can also check our two websites, https://flycorvair.net/ , http://flycorvair.com/ . 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 750 builders.
Above, the flying 2850cc Zenith 750 built by Gary Burdett of Illinois. It has our full complement of Zenith installation components and one of our production engines.
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 for the Zenith 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) – An example of our ling standing working relationship with Zenith: Friday out of shop until 4pm.
e) – A direct explanation of what makes my work different than typical LLC’s : 2011 Outlook & Philosophy
f) – A moving statement of philosophy: Sterling Hayden – Philosophy
Above, the 3,000 cc Corvair, configured for a Zenith 750. 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.
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 dispacements 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.
I have broken down building a Corvair and installing it on your airframe into 42 “groups”. The previous link 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: http://www.flycorvair.com/products.html
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: http://www.flycorvair.com/manual.html. 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: http://www.flycorvair.com/videov.html 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 a 750 engine build : Shop perspective: Mastery or ?
d) – A story about engines running on our hangar Dyno: http://www.flycorvair.com/thrust.html
e) Engine of builder now working on 750 airframe: World’s Strongest 3,000cc Corvair, built by Greg Crouchley
f) 3,000cc engine we built for 750 builder Larry Hatfield: 3,000cc Engine Running
g) A story about the evolution on 120HP Corvairs: 3,000 vs 3,100 cc Corvair engines.
Headed to the 2012 Zenith open house, six of our powder coated 750 mounts. All of our mounts are welded in house, all of our parts are made in the United States.
3) Installation Components for the 750:
We provide every single part it takes to install a Corvair in your 750. You can buy them one at a time, or all at once. Ninety percent of these parts are common to our Zenith 601/650 installation, which has been successfully flying for a decade. Only the mount, the diameter of the prop, and the size of the air inlets is different. Our Zenith installation manual detail how and why each of the installation components are installed on your airframe.
The installation does not require any modification to the airframe fuel system like most EFI engines do. Being air cooled and carbureted, it 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 comparitively 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: http://www.flycorvair.com/products.html From that list, you can see that the major installation parts for a 750 are: #3601(S) intake manifold, #3901(A) Stainless exhaust, #4002 spinner bulkhead, #4003 Warp Drive prop, #4101 baffle kit, #4102 nose bowl, #4103 cowl kit and a #4201(B) mount. The other smaller items listed are detail in our Zenith installation manual. All of the above parts have links to stories through the products page, but just for an overview of a single part, look at this link: Zenith 750/Cruiser Mounts. P/N 4201(B)
Many people new to building initially think that very economical engines like the Corvair must also be inexpensine 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 for Zeniths have installation kits that run from $4,000 to $6,000. The Corvair is near the bottom of this range, but the savings of using the Corvair is in the engine, not the cost of installing it. Builders can save a significant amount of money by fabricating many of the parts like #4103, but most people are near the finish line at that point and opt to buy it and save the time. Exact cost on the installation parts varies a bit, I will be glad to review it with builders after they study the installation manual.
a) – For an example of 74 years of aircraft welding talent: Zenith 601/650 Motor mounts, P/N 4201(A)
b) – To learn about the Stainless exhausts we make: Stainless Steel Exhaust Systems
c) – A 2008 look at how we developed the 750 installation on one of the first kits:
d) You tube video of an engine we built running on a 750 fuselage, 2009: http://www.youtube.com/watch?v=y_1ov0DAbe8&feature=plcp
An overhead photo of a CH-750 installation we did in 2009.
Above, 2004 at Oshkosh: Next to our personal 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:
Beyond the basic engine and installation components, we offer many forms of support to Zenith builders:
a) We have a very detailed Installation manual for all Zeniths: http://www.flycorvair.com/601im.html We also have a flight operations manual with specific test flight plans and procedures: http://www.flycorvair.com/ops09.html
b) we hold 4 free hands on technical seminars called “Corvair Colleges” every year. This includes an annual College held in Mexico MO at the Zenith Factory timed to coincide with the factory open house in September. For an introduction to Colleges, read this link: http://www.flycorvair.com/cc21.html 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 http://www.youtube.com/watch?v=wfa85e3ibI4&playnext=1&list=PL1D40A102EC2A194D&feature=results_video
c) The “Zenvair” group is a separate on-line peer-to-peer discussion group just for Corvair/Zenith flyers to directly and freely share information and data with each other in a civilized productive format. The link is : ‘Zenvair’ Information board formed This is very effectively moderated by Zenith/Corvair builder and flyer Phil Maxson.
d) 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, including 2 at Zeniths west coast facility Quality sport planes, 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.