Quote:
Originally Posted by MichaelLevy
It may be more scale but there is a downside. I doubt 4 50mm fans will give you as much thrust as two 70mm. I don't rely on the manufacturers' data, they don't reflect actual "in plane" performance. I tested both the Freewing and Powerfun 70 mm units in plane and get around 1400 to 1500 gm static thrust on 6S. You'll be lucky to get 500gm from a 50 mm fan unit. They also sound a lot better than 50mm units...unless you like the sound of a dentist's drill . They are also factory dynamically balanced which is a huge advantage over doing it yourself. Also smaller fans are more inefficient which means your battery won't last as long in flight,and there's also the complexity. The thrust tube can be flattened toward the exhaust end so as not to affect the scale look. That's what I did in one of my planes. It doesn't affect the thrust.
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Yes Michael, you are right, the sound is quite differente,...I have A 50mm FMS 3S version, with 3S 850mAhLipo(75C), it gives me 720g thrust first seconds, than around 680gr on 32 Amps...Quite interesting looking in Wheight to thrust ratio...(EDF+ESC+LIPO=200gr)
And my test was just blowingair on the scale...my be more with a real thrust mesurements device.