Propeller motion blur with Cycles


I’m having a bit of a trouble with cycles motion blur wich don’t give me the results I’m locking for. I am trying to achive the typical propeller look with a greyish ring with the blured contours of the blades with the yellow tips you find on pictures of airplanes in-air and thought that would be piece a cake with cycles new motion blur, but it wasn’t.
What I got is somethin like this:

I have animated the propeller so it rotates with a speed of 36 revolutions per second = 2160 rpm, which is a little less than the rotation speed of a crusing Spitfire engine. Taking a look at the picture to the left where the shutter value was set to 0.100, (@24fps =~1/250 s shutter speed) it looks okay, but the motion of the propeller looks like a plane on the ground, idling, I would like a bit more blur. The one to the right looks just like a mess and the shutter speed is way to long anyways(~1/25s), but most important, the cap looks just awful, in both renders. Why?

I also tried to turn things around, increase the shutter speed and decrease the speed of the propeller to just 120 degrees per frame, but no difference.
Have tried old fashioned vektor blur also, but it looks even worse.

So, how do I get the cap to not be transparent? The blades are okey in the left render, but why is the cap transparent? I have tried to reduce the rotation speed of the cap to 40% of the propellers, ant it looks much better, but it’s still transparent towards the edges.

Funny, this is exactly what I am looking for too… and man, your Spit is better than mine!

Any chance you could post the .blend? My tests of similar objects render just fine.

I setted up a scene with a Bf-109 and tried the same thing and it worked just fine, so I went back to my spit and after some tests I found the fault.

The object center of the propeller and its cap had been moved to the origo instead of the center of rotation. It looked okey in viewport but for some reason it caused some problems in the render.

Thanks anyway and keep your eyes open for a full scene render!