Rotary Car Club - View Single Post - 4 or 5 Blades. Which is better? radiator cooling

Dr-Rotor · 08-07-2008, 01:41 PM

Guys.....the reason for the whole thing is Noise. If you look carefuly at the fans you will see that the blades are not even spaced evenly apart. Mazda designed it this way so that when both fans are running they cancel eachother out to make a nice quiet system.

Its harmonics, thats why one fan has 4 & the other has 5 blades. Much like a 2 blade helicopter has a much louder rotor slap than a 5 blade system that has more of a buzz than slap like the Hueys do. This is why the rear tail rotor on the Apache is not an exact cross pattern, its to loud. So they moved the blades closer to eachother to reduce noise. Same reason why those helis with the inclosed tail rotors are so quiet like the Comanche.

Sorry for the heli talk but thats the only way I could give the right example.

08-07-2008, 01:41 PM	#6
Dr-Rotor Rotary Fan in Training Join Date: Aug 2008 Location: Auckland Posts: 70 Rep Power: 18	Guys.....the reason for the whole thing is Noise. If you look carefuly at the fans you will see that the blades are not even spaced evenly apart. Mazda designed it this way so that when both fans are running they cancel eachother out to make a nice quiet system. Its harmonics, thats why one fan has 4 & the other has 5 blades. Much like a 2 blade helicopter has a much louder rotor slap than a 5 blade system that has more of a buzz than slap like the Hueys do. This is why the rear tail rotor on the Apache is not an exact cross pattern, its to loud. So they moved the blades closer to eachother to reduce noise. Same reason why those helis with the inclosed tail rotors are so quiet like the Comanche. Sorry for the heli talk but thats the only way I could give the right example. Last edited by Dr-Rotor; 08-07-2008 at 01:48 PM. Reason: spelling.