hypathetically .....
 

If someone were so inclined could you replace the main bearings with some that were based off roller bearins or even ball bearings., and if so what would be the benefits or downfalls. Just musing and thought I'd ask.

i think scoot did a roller center bearing. generally though roller bearings got tried in the 1920's and 30's and i gather they work on an engine that sees constant rpm, but when the engine has to accelerate and decelerate, the ball/rollers spin in the races, and it wears out.

i'm not an expert, but i wouldn't be quick to write off something from the 30's just cause its old, they had 4 valve/dual cam/supercharged engines with cockpit adjustable dampening.

So, some sore of dynamic breaking to assist in slowing the rotating assembly or just use a dry sump to maintain lubrication as much as possible. Even if roller bearings won't work with today's technology how about some sort of ball bearings. It's good enough for a turbo and they spin alot faster than an engine.

The Army's Shadow 200 UAV uses a single rotor on a roller bearing. But those 40hp single rotor engines literally use oil once for lubrication before spitting it out the back. They are also air cooled, even inside the rotor. I wish I could get a picture of the inside, but I doubt that would fly through the classification loops.

As for a high horsepower application, I think the journal bearing with adequate oil pressure would probably still be the most reliable. The bearing races on the shadow's engine were all blued from heat, along with all of the portions of th rotor that were thicker and didn't receive extra cooling air due to the design. Not to mention, the rate of replacement of the engines is pretty high.

I am no bearing expert, but I wonder how a roller bearing would hold up over time?