Sources: Choosing a 5th Bearing

This is part two in the ‘new sources’ series.

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Builders.

The most basic decision on building a Corvair Engine is which 5th bearing to use. While people still do build 4 bearing engines, and it is possible to later upgrade these with Weseman Gen I retro-fit 5th bearings, my conversion manual outlines the logic of why it is preferable to start the build with a 5th bearing, and why in the big scheme of things why builders on a budget should elect to delay things like radios or elaborate paint jobs instead of putting off a 5th bearing.

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5th bearings have been around Corvairs for more than 10 years. Between 1960 and 2005 virtually no Corvair used a 5th bearing, but with the increasing output and wider range of applications we used the Corvair for, it because understood that they are a very good idea on modern engine builds. Because the Weseman Gen I bearing is retrofit-able and very affordable, almost half the fleet flying before 2005 has be retrofitted with them, and with the addition of Gen II bearings for new engine builds, Weseman 5th bearings have come to completely dominate the fleet of flying Corvair powered planes. The Weseman’s have produced hundreds of them, they work, they are affordable, they are field installable by the builder in a few hours, They are built of the highest quality CNC equipment and they are well supported. For these reasons, they outnumber any other design by more than 10 to 1.

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In our Conversion manual, We discuss three different bearing designs. They are Group 3000 Weseman Bearings, Group 3100 Roy’s garage Bearings, and Group 3200, my 5th bearing design. This article series is on making good source choices for progress. I will cut to the chase here and say it plain: If you are serious about building and flying, Choose a Weseman Group 3000 bearing (either a Gen I or II) for your project, period.

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IMG_2313

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Above, Close up showing Weseman Gen II billet 5th bearing. Early models had heat treated cast housings, but for many years, both Gen I and Gen II Weseman bearings have Billet aluminum housings made on CNC machines by a major aerospace manufacturer. These housings have bearing inserts from an American V-8 that are easily and inexpensively replaceable, without having to split the case. The housing is indexed to the case, and can be removed and replaced, and it goes right back into index. I have installed dozens of these on Corvair flight engines. They are readily available, in stock, on the shelf items available, along with matching cranks from the Weseman’s:

https://flywithspa.com/corvair/

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Consider this: I have my own bearing design,  Group 3200;  It has been proven for almost ten years, it has flown hundreds of hours, I have one on my own plane. I could promote them and sell them for a profit, but I don’t. My motivation isn’t to just sell things and make money, it is to recommend the best parts and sources for builders, and this is more important that egotistically promoting something because I thought of it and made it, when there is something that when considered objectively, better serves builders. This is why all the production engines I build have Weseman bearings on them, and why strongly recommend them to every builder.

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The bearing from Roy’s garage is Group 3100 in the manual.  It is a good design, and no one has done more than I have in the past to promote Roy’s work as an option. The limitation of the design is that each case and crank must be shipped to Roy, where the bottom end has to be hand machined by Roy. This is a labor intensive process, and if he was doing nothing else, he would be pressed to make 20 assemblies per year. In the past I have had Roy as a guest at many Colleges and for several years in my booth at Oshkosh. For a long time he has had a back order list well over a year. Instead of ‘sticking to the knitting’ and addressing this, he has spent hundred of hours on “R&D” goose chases. At the start of 2015, I quietly told him I was no longer comfortable promoting his work or having him come to colleges, as it didn’t seem he was serious about getting caught up. His response has been to spend his time developing a ‘secret’ modification to allegedly make 20% more power, telling builders that our CNC parts don’t fit Corvairs, and trying to promote the idea that he alone, a guy without a pilot’s nor A&P licenses, who has never owned any plane, somehow knows better than anyone else how to build and operate these engines. I have been working in experimental aviation for more than 25 years, and let me offer the observation that many people who started with a good basic product, but came to see themselves as more brilliant than everyone around them, didn’t last much longer.

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Many builders understand that it will take several years, on average to build their plane. That is fine, but builders need to choose their sources carefully. and not start off by sending their case away for a year or two when a better option exists, when they can make immediate progress. A builder, signed up for a college, can simply call the Weseman’s and buy a bearing right off the shelf, we can bolt it together at the college, and with little effort head home with a closed case. That is getting a year head start on the process. It also costs less money. For anyone who might claim that my endorsement of the Weseman bearing is related to money, guess again. When I put one on an engine, I pay full price for it, and because I live in the same state, I pay tax on it. My promotion of it is simply because it is the best option for any builder who wants to make progress.

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-ww.

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About William Wynne
I have been continuously building, testing and flying Corvair engines since 1989. Information, parts and components that we developed and tested are now flying on several hundred Corvair powered aircraft. I earned a Bachelor of Science in Professional Aeronautics and an A&P license from Embry-Riddle Aeronautical University, and have a proven 20 year track record of effectively teaching homebuilders how to create and fly their own Corvair powered planes. Much of this is chronicled at www.FlyCorvair.com and in more than 50 magazine articles.

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