<VV> Flight Corvairs

[Dave Thompson]

Bryan,
You are absolutely right. 

The Corvair crank was not designed to handle heavy flight loads. Without the
"5th bearing" you could only swing a light prop and it was highly
recommended to NOT do aerobatics. This limited the engine and airframe.
Another limitation was that all the variable pitch props available to 100HP
flight engines weighed too much, thus could not be used. The idea, as I
understand it is that the 5th bearing takes the majority of the flight load.
This allows the use of variable pitched props and light aerobatics, along
with a larger safety margin. 

For those who do not know, keeping things very simple, a variable pitched
prop can be compared to a car transmission. A flat pitched prop will give a
good climb rate where a course pitch will give you speed. A fixed pitch prop
has to be a compromise. A variable pitched prop can be "dialed-in" for both
climb and cruise, kind of like switching gears on a car for different road
conditions and speeds. They are also necessary to get the best performance
from a turbocharged flight engine.

For those that are interested and want more info, I recommend you refer to
the following site:

www.flycorvair.com

Dave Thompson

-----Original Message-----
From: Bryan Blackwell [mailto:bryan at skiblack.com] 
Sent: Monday, March 22, 2010 9:59 AM
To: HallGrenn at aol.com
Cc: Dave Thompson; Virtual Vairs
Subject: Re: <VV> Flight Corvairs

I believe it's to handle the load the prop puts on the crank.

--Bryan

On Mar 21, 2010, at 11:27 PM, HallGrenn at aol.com wrote:

> Kinda intrigued by the fifth bearing one engine had--no room on our cars  
> and no need for my operation, but still a neat idea.