Mohanakannan
Active Member
Hi all
I've built a set of wooden rotor blades with NACA0012 airfoil and I added noseweights. Since the density of wood is constant through out the blade it balances at about 40% of the chord. In order to make the blade balance chordwise at about 25% we attach nose weights. I tried having these noseweights at the spanwise location given in the plans of Hobby Choppy helicopter, it worked perfectly fine and was able to lift the craft (The craft was teathered to ground by the way). When I changed the nose weight location by bringing it towards the inboard (The static chord wise balancing will still be achieved where ever the nose weight stays along the span) the blades doesn't seem to cross certain RPM, I know it is because the blade nolonger balances at 25% of the chord (dynamic balancing) and of the large moment arm twisting the blade increasing its pitch creating more drag. It aslo leads to blade slapping at about 70% of the design RPM. I would like to know how the nose weight location (Span wise) has been calculated for this application so that I can make modifications to it. Can any one please help me out by providing any proven calculations for nose weights if you have. I have attached a picture of a set of bensen blades with nose weights.
Regards
Mohan
I've built a set of wooden rotor blades with NACA0012 airfoil and I added noseweights. Since the density of wood is constant through out the blade it balances at about 40% of the chord. In order to make the blade balance chordwise at about 25% we attach nose weights. I tried having these noseweights at the spanwise location given in the plans of Hobby Choppy helicopter, it worked perfectly fine and was able to lift the craft (The craft was teathered to ground by the way). When I changed the nose weight location by bringing it towards the inboard (The static chord wise balancing will still be achieved where ever the nose weight stays along the span) the blades doesn't seem to cross certain RPM, I know it is because the blade nolonger balances at 25% of the chord (dynamic balancing) and of the large moment arm twisting the blade increasing its pitch creating more drag. It aslo leads to blade slapping at about 70% of the design RPM. I would like to know how the nose weight location (Span wise) has been calculated for this application so that I can make modifications to it. Can any one please help me out by providing any proven calculations for nose weights if you have. I have attached a picture of a set of bensen blades with nose weights.
Regards
Mohan