Hi chasni
What are you studying in college? I'm a retired Mechanical Engineer. I hope you will believe the following and learn something from it. When I was a young engineer I made a mistake with the cooling propeller on an engine driven air compressor I had designed. I had purchase the wrong propeller (In that application it is called a cooling fan, like in a car) and it cost my company a great deal of money, but I learned something that almost know body flying R/C plane knows. So I'm telling you an open secret. The propeller on our R/C planes can be mounted in one of two ways. In this discussion DO NOT CHANGE THE DIRECTION OF ROTATION OF THE MOTOR. In each of the two ways the air will blow in the the same direction. Please read this again because you stated this wrong in one of your earlier posts and that is why I am writing this. When mounted correctly the propeller will give 100% performance. When mounted backward the air will blow in the same direction as before, but the amount of air will be greatly reduced. I cannot remember the correct figure but I believe the performance drops to about 60%. I am writing this in consideration that English is not your first language so forgive me if I am writing this exceptionally clear and simple, and repeating things. If you look at the end of your propeller from the tip toward the center you will notice that one side is more rounded than the other. The rounded side is similar to the top of the wing on your plane. This rounded side must be toward the direction of travel of the plane. The more flat side is similar to the bottom side of your wing. The propeller will also have a rounded leading edge (LE) and a sharp trailing edge (TE), just like the wing on your plane. The rounded LE must lead the propeller as it rotates, and the sharp trailing edge must trail the propeller, just like the wing on your plane. Now you know more than maybe 95% of the people flying R/C. You do not have to know any of this to fly R/C. If you see a plane that cannot get off the ground, the propeller may be mounted backward. Please do not judge correct propeller mounting, as I have seen many others do, by the location of the lettering on the propeller. Not all propeller manufacturers put the lettering on the same side. Let me know what you think about what I have written. This is not complex, but it is possible I wrote something wrong. If you or someone else sees a mistake I made, please let me know.