5th Bearing for Corvair Flight Engines

Welcome to fly5^thbearing.com, home of the BTA  5^th bearing for Corvair engines converted for flight.  I got into the Corvair movement  during the initial stages of building N183SX the Cleanex.  I was looking for a economic engine to power the Sonex I was building.  To make a very long story short I meet William Wynne and decided to use the Corvair engine on my airframe.  After flying a 3100cc William Wynne style Corvair for about 40 hrs I cracked a crankshaft.  Around this time several others had also cracked crankshafts.  We turned to Nitriding to help increase the fatigue life of the crankshaft.  That worked well but in early 2008 my friends Chris Smith (Cleanex 2) and Mark Langford (KR-2S) both broke nitrided crankshafts!  That was a wakeup call to me!  I decided to ground N183SX and put a extra bearing up front to take some of the flight loads off the crankshaft.  You can look to Mark Langfords site and, of course,  flycorvair.com  for the complete story on cranks.  I also decided to get a little help.  My father, Jim Weseman, was building a Fisher Celebrity and considering engines.  He has flown the Cleanex and likes the Corvair but also had other engines to consider.  Jim Weseman is a long time Pilot, A&P IA, Engine Guru, home machinist, welder, and generally speaking a very creative guy!  Knowing how Continental and Lycoming chose to handle propeller loads with a HUGE bearing up front, he was never thrilled with the bearing setup on the Corvair.  While we were working on this we had a lot of requests for info but decided to test first.  Here is information on the history and testing. Thanks for looking.

  When we started we both had several ideas from the most simplistic approach to some very complex setups. We decided to go with a simple setup to take the bending load the propeller generates during flight off of the crankshaft and direct them into the case.  In stock form the loads are taken between the #4 crank bearings and across the #6 rod throws.  The basic idea is to put the load into the new 5^th and #4 bearing.  This takes the bending loads off the over stressed #6 rod throw and directs it to the new front housing and engine case.  The thrust loads are also of some concern.  The stock Corvair thrust bearing is all the way at the other end of the crank.  Aircraft engines have the thrust bearing up front, part of the HUGE bearing mentioned above.  It is not hard to add a thrust bearing and remove the stock one, but it is hard to remove the existing one from a already assembled engine!  We had some decisions to make.  Designing a thrust bearing would require the engine to be torn down to install it and remove the existing thrust bearing.  We had studied the VW crank problems and the non thrust add on bearing is a complete success story.  Several others, including William Wynne and Roys Garage, are working on both thrust (WW) and non thrust (Roy) designs but both needed to be installed during build up, or a complete tear down and rebuild.  We looked over the tolerances and decide we could do it as a bolt on for my engine.  It had been running great for over 100 hrs and I really didn't want to tear it down and rebuild it just to start testing stuff.  Now that dad was involved and getting more knowledge on the Corvair he was leaning toward using a Corvair and would need a unit also.  Chris Smith also looked over what we were planning and asked if we would consider putting one on his.  So we needed more than one!  We have some foundry contacts so decided to make a pattern and have the housing cast to reduce machine time and cost.  The inner bearing was machined and carefully checked for run out.  So, parts in hand we tore the Cleanex apart and installed the first unit.  Things went well and we did the first test runs.  After about 3 hrs on the ground I flew it for the first time.  Things went as planned and we continue to wring it out.  Look to the news page for current test time and conditions!

OK - WHAT DOSE BTA STAND FOR?

    When talking with William Wynne one afternoon he pointed out that the stock nitrided crank does a good job in most applications.  So we just need a little extra support to get a large safety factor.  It just has to be better than air??  Better Than Air.  We don't think this is the only way or the best way, but it does work and has proven to do the job it needs to do.

WHAT'S NEXT/ARE THEY FOR SALE?

Yes - they are for sale!  See the order pageto place your order now.  We have had a lot of interest from people who want to buy these units.  Although we didn't work on this to start a new company, we do feel it would serve a lot of people's needs. 

Due to the install-it-yourself and the design itself, the cost can be kept down.  We feel that if it cost over 1100.00 to install it was too much!!  With this in mind we can supply the bearing kits and cover our expenses.  One reason flying Corvairs are popular is because they are relatively inexpensive and adding several thousand dollars to the total cost by using more expensive bearings is really cutting into the value.  The cost will also reflect that these are EXPERIMENTAL and we are all part of the test pool.  Please feel free to use the message board on the order page or contact us for more info.  

Thanks - Dan Weseman