It depends on what you want to achieve, I think...
As far as I am concerned, I'd say that it is a "trial by error" procedure: you have to try different settings and pick the best one or the one that fits best for you.
For me, the best setting is the one that gives me "safety" but that gives me the blurry on the props (generally, it is not a "total blur").
With more light hitting the sensor, you will have to close the diaphragm in order to compensate: you can both do it manually in full manual mode or leave to the camera this duty by selecting time priority mode.
However, always bear in mind that slower shutter speeds may end up into blurry images... so, steady hand!
Finally, I always start from this settings and then I adjust:
- 1/160 or slower for helicopters
- 1/250 or slower for props
Generally, on a bright sunny clear day... no wider than f/8
Now it's up to you to have fun trying it out!
[Edited 2012-11-20 10:37:16]