John -
You are RIGHT ON about the pilot keeping the RPM's pegged!
My rule of thumb for shutter speeds is as follows:
2 blade prop - less than 1/100th to get the full fan effect
3 blade prop - Less than 1/160th to get the fan
With each of these I am using electronically stabilzed lenses in addtional to smooth air and a light steady grip to keep the plane sharp. You can also use a bottom mounted gyro stabilizer to keep things tight. Those work great and can be rented at most photo stores!
If I try and hand hold a 200mm lens at less than 1/100th even on the ground my images blur. In the plane it's even worse hense the "VR" or Vibration Reduction lenses.
...hope this help!
- Peter
PS - Don't shoot through the windows if you can help it or your shots will have dull color like the one above. Also, put the sun in front so it will reflect off the prop and move the shadows back on the plane so it looks like it's moving forward. (see shadow under HS...would look funny pointed the other way)