|
|
Ernest Christley wrote:
Bryan Winberry wrote:
Thanks Ernest,
Can you splain me one thin. How does the AoA change on a fixed pitch prop?
The blade move side to side.
The airplane move forward (for non-aerobatic modes of flight).
The AoA is affected by the relationship of the side-to-side and forward motions.
Twirl a flat blade with the brakes locked. The AoA is zero degrees.
With an engine out, and prop stopped and flat. The AoA is 90 degrees.
Under normal operation. The AoA is a vector sum of the forward movement and the side-to-side movement.
Oh, another thing that makes it even more interesting.
The vector sum of the "forward movement" to the "side-to-side movement" is different for each section of the blade. Each section as you step away from the center of the hub moves from side to side at a different rate. The outside pieces have to make a bigger circle than the inside pieces, so they have to move faster. But the forward motion is all the same. At 200kts, for instance, you can potentially have a problematically twisted propeller where the tips are stalled yet the blade near the hub has a negative AoA!!
|
|