A hard question to answer :-(

[Travels with Yoly]

I've only had my P4 a couple weeks and only flown it about 5 times (weather not cooperating). I had a P3A for a year prior to getting the P4 and flew it dozens and dozens of times maybe 75 flights. I made several bonehead moves early on and paid a financial price to learn those lessons. In the end though, I felt very comfortable and secure flying the P3 and it was actually very reliable and trustworthy once I got the hang of it. I also became quite familiar with it with all my senses.

Now I have the P4 and am doing smaller flights reaching out further little by little until I gain that same confidence. I know that the P4 uses slightly larger motors than the P3 and I am now wondering if they produce a sound that my P3 didn't. I hear a distinct high pitch whine that is RPM sensitive above and beyond the normal whooshing sounds of the prop wash. If I hover the craft at eye level or just above me I hear it plain as day. If I accelerate the craft straight up I can hear the note of the whine increase in pitch until the craft gets out of ear shot. As I bring it down I can hear the whine grow louder as it gets closer to me. So my question is .... does anyone else hear this additional sound, or is it just me. Is it possible that there's one motor with a slightly tighter tolerance somewhere in the assembly that will break in and decrease as it gets some hours on it ? Or is it a portent of things to come (motor failure) ? Or do you think I should take advantage of a Feb 5th return date option ?

 

[Fancher9-76]

Yes absolutely I can hear exactly what you describe. I run my P4 in atti mode at WOT all the time. I have heard the exact same noises you describe with you're P4 with my P4 day 1.

 

[Meta4]

I am now wondering if they produce a sound that my P3 didn't. I hear a distinct high pitch whine that is RPM sensitive above and beyond the normal whooshing sounds of the prop wash.

Your P4 has an additional internal fan that the P3 never had.
See the slots in your battery?
The internal fan keeps fresh air blowing through the slots to prevent overheating.
That's what you can hear - it's perfectly normal.

 

[rocketflyer]

That's what you can hear - it's perfectly normal.

OP is describing a fairly loud sound which would be way more than the tiny cooling fan can produce?

OP, I hear something similar on my P4 as well. It was quite disconcerting coming from a P3 but does not seem to be an issue.

 

[Erised]

Yepper you can hear that whinny pitch 100 yards out, I have over 3,000,000 feet and my P4 still has that same here she comes whine, pretty nice sound when your craft is coming home RTH.

 

[Travels with Yoly]

Thank you everyone, so much. This is definitely great news. I wondered if it was fan noise but dismissed it due to the pitch which sounds like a high pitch turbo. I also didn't see why a fan would be driven at motor speed, rather than a fixed speed. I also wondered if I was hearing things and also if anyone else had heard it since hearing in humans is subject to such a wide range of frequencies. The craft is certainly louder than my P3 ever was. I guess I'll just have to get used to it

 

[Erised]

If you wish to hear only the whine, leave the props off and arm the motors with the bird on your kitchen table. Would you like a little bit of chesse with that whine. You won't hurt the motors if you do this for a few seconds, you can even give it a little bit of throttle for kicks, just a little bit and you will understand why you can hear it far away. A few seconds of low speed run time will barely warm up the motors.

 

[Meta4]

I also didn't see why a fan would be driven at motor speed, rather than a fixed speed.

When the Phantom's motors are revving hard and the battery is called on to deliver a lot of current is when the cooling is most needed.

 

[Travels with Yoly]

Two points to the above 2 comments .... (Erised and Meta4)

1) When I first got the P4 and did the updates, the first thing I did was arm the motors just as a check. I did not hear the whine at that time ... I will check it again.
2) I hear the whine when the battery is 100% and the bird is just hovering after initial lift off (before any real heat is generated.