Hummingbird feeders in high winds

[SoobieOut]

Just an observation. Today during a violent thunderstorm with 60+ MPH gusts I happened to notice that the Hummingbird feeder on the deck did not move at all during the storm.



At the same time the other bird feeders, which are cylindrical, swayed 12" or more.

Just wondering if anyone has ideas why this hummingbird feeder is not affected by the wind.

Wish I had a wind tunnel to see at what speed it does start to sway.

Maybe this shape, or the bar spacing is key.

[Patrick]

Large mass to area ratio and relatively good streamlining? Plus the birds were holding it in place. :-)

[TomO]

My plastic bird bath stays perfectly still in up to 70MPH gusts, and it's not even tethered down!

It has almost the same shape as that bird feeder pictured, but relieved on top to hold water (of course).

I think that the cross-section plays into the equation immensely. It seems like my bird bath acted as an inverted wing and created down force as the wind blew across it. The water adding weight was helping too.

[brucepick]

Outer circular ring is breaking the air flow before it hits the main body? So that air flow is somewhat spread out and also pre-disturbed when it hits the food tray?

And kinda the same thing on the downwind side. The outer ring might serve as a virtual extension of the main body, lengthening its apparent profile.

[dcb]

Like Pat said, a big factor is the side area/weight ratio.

cylinder equations:
volume = r*r*pi*h
side area = r*2*h

examples

height 1, radius 1
Volume = 3.14
side area = 2

height 1, radius 2
Volume = 12.56
side area = 4


so doubling the radius, doubled the side area, but quadrupled the volume (i.e. amount of sugar water). Of course it matters how much the feeders were filled, and if there were any wind shielding variables.

[euromodder]

The angles divert the wind over and under the feeder.
Its cross-section is much like how a long tie-bridge's x-section gets constructed these days.


The ring likely helps as well, creating a V-shaped area of lower wind force - like the pole extending in front of the pilot on a Russian K36 ejection seat.

[dcb]

oh my gammit