"Weathervaning" a low-drag surface for a quadcopter arm

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Inverted Vantage

Formerly Unknown Target
Joined
Jun 19, 2008
Messages
1,116
Hi everyone.

You've probably seen these things flying around a lot lately:

zmr250kit-2.jpg

The "Arms" are the things that hold the motors on the end.

I want to 3D print a quadcopter frame, and I would like to streamline the arms. Right now they are flat plates, so when the quad is tilted forward, they end up creating some amount of flat plate drag. The difference between streamlining and not streamlining will be, I suspect, negligible, but I would like to see if it's even possible to do what I'm talking about.

In my mind I've got a piece of balsa with a motor attached to one end and the other rooted in the fuselage. Around that balsa beam is some sort of plastic covering that rotates according to oncoming airflow. Since most of the airflow is from the motor, I imagine that it would be sticking mostly upwards - but when the aircraft is in forward flight, some of the relative air would tip that covering forward to align it more with the oncoming airflow.

I was just wondering if anyone had any idea how to do this? I think it would be cool.

Cheers! :)
 

bmcj

Well-Known Member
HBA Supporter
Joined
Apr 10, 2007
Messages
13,346
Location
Fresno, California
Have a round rod arm and wrap it with a streamlined sleeve that can rotate freely to match the free-stream direction.

Personally, I think you are chasing a fix for something that has very little impact at the speeds you fly.
 

Inverted Vantage

Formerly Unknown Target
Joined
Jun 19, 2008
Messages
1,116
I know, I don't think it will matter in terms of speed. It's more about the Rule of Cool.

What I was worried about with that approach was the covering inverting - so it starts level and if it's streamlined with a fat end and a pointy end, like a symmetric airfoil, it ends up with the fat end pointing down as soon as you give it throttle, or it just spinning wildly.
 
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