Hi all,
So, hopefully, I'll get somewhere with this question. I did get some help on another forum, and then the question bank threw me off completely. From the Oxford books, this is what I get (sorry, can't seem to post images):
As the aircraft accelerates, air speed will increase, causing a decrease in the angle of attack of the blades. Less thrust and less propeller torque will be generated.
But then the question bank ...
As an aircraft with a variable-pitch, constant-speed propeller accelerates along the runway:
[A] The blade pitch angle increases, maintaining a constant angle of attack and R.P.M. ✅
The angle of attack will remain constant and the engine R.P.M. will increase.
[C] The linear velocity of the propeller tip will gradually decrease.
[D] The angle of attack will decrease and the engine R.P.M. remain constant.
So, what exactly is it? I tried to deduce the answer, i.e. compare with a fixed-pitch prop, as the aircraft accelerates, the relative wind angle changes (moves forward), therefore the AoA decreases. OK.
With a constant speed, I select an RPM say, 2500. When I start to accelerate, then due to the forward speed, the blade tries to rotate faster > this causes the CSU to slow it down, making it more coarse to reduce and control the RPM, so again the blade pitch angle will increase, and maintain a constant RPM.
Is that correct? What will cause the blade to rotate faster when accelerating? And what happens to the AoA?
Many thanks for your help!