ORIGINAL: MajorTomski
Ahh but... The swirl theory is based on the assumption that the propeller imparts energy to the air particles that causes them to move in the same direction as the propeller. This is the source of the clockwise rotation. The problem with this is that it violates airfoil theory. Air particles moving over an airfoil are forced down and AFT. To make the slipstream work they'd have to go down and FORWARD! (neat trick if you can do it) I have access to a book written before Stick and Rudder that points to a mathematical solution showing that the airflow from the propeller is a winding sheet bounded by the propeller root, or the fuselage, and that vortex we see in the picture. Again that sheet has the air flow running around the fuselage in a counter clockwise path. Or at best straight back from the prop. Again no swirl in the slipstream. Then again try to find a shot of an aerobatic airpane with smoke on in just a straight high G pull up. This is where the slipstream says stuff should be wrapping around the fuselage. Yet I've been unable to find anything like that.
Two little tests will fix the problem.
First stick a prop blade into a pan of water & stir it using a cylindrical movement approximating blade motion in the air -- what happens to the water.
Next, go out to your hanger, start up your Extra 300 & rev it up. Turn on the smoke & hold it up over your head -- then tell me what you see.
Probably moot points -- Red seems to have interjected something that will wreck the argument -- NASA evidence!!
What about the pro-verse roll?