NCguy

just got a Razor 2500a and put it in my Formosa. The setup is Razor 2500a with planetary/Phoenix 25/TP2100/ and APC 10/7 slowfly. The performance is breathtaking.

This is my first brushless. The motor runs very smooth and quiet after it first engages. If you engage quickly it makes a slight pop when it starts. If you engage slowly it almost grinds and has a gear sound when it first engages and the noise goes away after you get a little rpm. The same is true when you throttle all the back. When the motor cuts off there is a gear grind sound and its a bit more pronounced then the noise it makes when it first engages. Also, if you throttle off and coast with no power you can hear the gear grind noise as the prop free wheels in the air. I have the phoenix brake on the default setting which is slow stop I think. With a little rpm this motor runs smooth as silk. Does anyone have a clue as to why it has this noise as it engages and disengages? Do I have a defective motor?

Bill Mixon

I don't have that motor or control, but a rough start on sensorless brushless motors is normal. When you say it "pops" on a quick start exactly what do you mean?
Not sure about the noise when it's freewheeling, but if it's smooth with power applied then it's probably not a gear drive issue.
I'm thinking it's something to do with the controller.

I would try it with the brake turned off and see how it does.

BTW, Welcome to RCU

Bill

NCguy

Thanks for the reply Bill. The "pop" is a quick gear noise if you engage quickly. The slower you engage the more pronounced the gear type sound becomes. And you have the same gear type noise if you windmill or shutdown the motor. After the motor starts and power is applied it is very smooth and no noises. Someone else mentioned that Razor motors have extreme "cogging" and that is the source of the noise . They suggested that I try the fast start option on the phonenix 25 and hard brake. Basically anything to keep the motor from turning slowly on its own without power. It makes sense since this motor does "ratchet" if you turn it with no power applied. I haven't tried this yet but I will and reply back.

Matt Kirsch

My Feedback: (21)

That ratchet you feel is what they mean by "cogging." What's probably happening is that this natural phenomenon, caused by the extremely strong magnets in the motor, is actually reverbrating through the airframe, amplifying the noise and making it sound much worse than it really is.

A pop is normal for many/most brushless motors on startup, as Bill stated. The sensorless controller is trying to figure out how to make the motor turn, and for a split second, the motor actually turns backwards. If you watch closely, sometimes you can see the motor tick back and forth before it starts to turn.

If you want a real rattle-trap, check out a Hitec Sky Scooter Pro II. The low-frequency speed control they use makes the plane sound like a bench grinder at anything below full throttle

NCguy

Thanks Matt, I think you're correct about the noise. Is it the concensus that I will be better off turning on fast start and hard brake to keep the motor from cogging while power is not present?

rmh

Owww- the hard brake is not a great idea - call the Castle Creation guys -
something is not right - it may not be the controller .
hard brake can loosen props .and maybe beatup the gear box.
soft or zero brake is a lot easier on things.