Go Back   EcoModder Forum > EcoModding > Aerodynamics
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 10-05-2011, 12:16 AM   #1 (permalink)
Polymorphic Modder
 
SoobieOut's Avatar
 
Join Date: Aug 2010
Location: Utah
Posts: 307

2006 DaCivic Hybrid - '06 Honda Civic Hybrid
90 day: 45.16 mpg (US)
Thanks: 188
Thanked 40 Times in 25 Posts
Hummingbird feeders in high winds

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.

  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 10-05-2011, 07:39 AM   #2 (permalink)
Master EcoModder
 
Patrick's Avatar
 
Join Date: Apr 2008
Location: Northern Florida, USA
Posts: 510

Hot Tamale - '10 Toyota Prius III
Thanks: 27
Thanked 96 Times in 70 Posts
Large mass to area ratio and relatively good streamlining? Plus the birds were holding it in place. :-)
  Reply With Quote
Old 10-05-2011, 01:35 PM   #3 (permalink)
That VX guy!
 
TomO's Avatar
 
Join Date: Nov 2007
Location: Mini Soda
Posts: 829

The VX - '92 Honda Civic VX
Thanks: 75
Thanked 80 Times in 53 Posts
Send a message via AIM to TomO Send a message via Yahoo to 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.
__________________

  Reply With Quote
Old 10-06-2011, 07:43 AM   #4 (permalink)
OCD Master EcoModder
 
brucepick's Avatar
 
Join Date: Dec 2007
Location: Eastern CT, USA
Posts: 1,933

Outasight - '00 Honda Insight
Team Honda
Gen-1 Insights
90 day: 54.18 mpg (US)
Thanks: 429
Thanked 391 Times in 261 Posts
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.
__________________
Coast long and prosper.
Driving '00 Honda Insight, acquired Feb 2016.


  Reply With Quote
Old 10-06-2011, 08:49 AM   #5 (permalink)
dcb
needs more cowbell
 
dcb's Avatar
 
Join Date: Feb 2008
Location: ÿ
Posts: 5,038

pimp mobile - '81 suzuki gs 250 t
90 day: 96.29 mpg (US)

schnitzel - '01 Volkswagen Golf TDI
90 day: 53.56 mpg (US)
Thanks: 158
Thanked 269 Times in 212 Posts
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.
__________________
WINDMILLS DO NOT WORK THAT WAY!!!
  Reply With Quote
Old 10-06-2011, 08:50 AM   #6 (permalink)
Master EcoModder
 
euromodder's Avatar
 
Join Date: Jul 2010
Location: Belgium
Posts: 4,683

The SCUD - '15 Fiat Scudo L2
Thanks: 178
Thanked 652 Times in 516 Posts
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.
__________________
Strayed to the Dark Diesel Side


Last edited by euromodder; 10-06-2011 at 01:06 PM..
  Reply With Quote
Old 10-06-2011, 09:02 AM   #7 (permalink)
dcb
needs more cowbell
 
dcb's Avatar
 
Join Date: Feb 2008
Location: ÿ
Posts: 5,038

pimp mobile - '81 suzuki gs 250 t
90 day: 96.29 mpg (US)

schnitzel - '01 Volkswagen Golf TDI
90 day: 53.56 mpg (US)
Thanks: 158
Thanked 269 Times in 212 Posts
oh my gammit

__________________
WINDMILLS DO NOT WORK THAT WAY!!!
  Reply With Quote
Reply  Post New Thread


Thread Tools




Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com