Dear Victor,

The propeller produces lift, just like the wings (the blades of the propeller are effectively little rotating wings), only the propeller is sideways, so the "lift" pushes the airplane forwards, instead of pushing it upwards.

Dear Mr Amin Ebrahimi:

Thank you for your answer, perhaps you would like to explain whether the lift force of the propeller airplane is caused by (a) Newton's action-reaction or by (b) Bernoulli equation?

Thank you once again and best wishes, Victor Christianto

Both. Each provides an explanation from a different point of view. The propeller pushes the air that goes through it and makes it go faster. To achieve this, it exerts a force on the air that goes through it. From Newton's 3rd law, the air pushes back on the propeller and this is our thrust.

Looking at each blade, they operate like small twisted wings. The air over the top moves faster than the air over the bottom because of the more pronounced curvature on the top. Hence, from Bernoulli we expect lower pressure on the top and higher pressure on the bottom of each blade. The bottom is facing aft; the top of each blade is facing forward. So, the pressure difference between top and bottom, integrated over the entire area of each blade, is our thrust:)

Thank you for answering, Nikos. All best wishes, Victor

Cambered airfoils can provide lift at a zero angle of attack, whereas a symmetrical airfoil will produce lift if it is at a positive angle of attack. This answer is to clarify Niko's excellent explanation.

Thank you, Jorge. Best wishes

Thank you very much, Viswanath, for your clear answer. Do you know a url which gives theory behind this question? Best wishes.

Ok, thank you very much, Viswanath. Best wishes

https://www.grc.nasa.gov/www/k-12/airplane/bernnew.html