Aerofoil characteristics of open gazebos vs closed
Discussion
Hope this can stay in BP&T for a bit
What is it about canvas open Gazebos that give them such good aerofoil characteristics?
The wind might only be light but there's some sort of magnifying effect that tends to want to pull the gazebo legs out of the ground
With the canvas walls fitted the wind doesnt get underneath and it's fine
Yet youd think an open gazebo would give less wind resistance than a closed one
What aerodynamic effect is going on?
What is it about canvas open Gazebos that give them such good aerofoil characteristics?
The wind might only be light but there's some sort of magnifying effect that tends to want to pull the gazebo legs out of the ground
With the canvas walls fitted the wind doesnt get underneath and it's fine
Yet youd think an open gazebo would give less wind resistance than a closed one
What aerodynamic effect is going on?
The side view of an open gazebo is a bit like a cambered aerofoil. The shape's curvature causes changes in pressure over the upper and lower surfaces and a suction effect (or lift) is generated. It's true that the air travels much faster over the upper surface than the lower, but this isn't necessarily due to travelling further; there's no physical reason why air particles have to meet up at the trailing edge (this is known as the "Equal-Transit Time fallacy").
A closed gazebo is more like a "bluff body" and hence drag is likely to be more significant than lift.
A closed gazebo is more like a "bluff body" and hence drag is likely to be more significant than lift.
Simpo Two said:
When I saw the title I thought you were planning to cross the Channel on a gazebo...
Nearly did 
You can get gazebos with a square tower type thing on the top to let the air out (on a hot day
)I guess theyre not much better as it's lift youre trying to remove not air
Can you get some sort of inverted canopy so the lift is downwards?
saaby93 said:
Nearly did
You can get gazebos with a square tower type thing on the top to let the air out (on a hot day )
I guess theyre not much better as it's lift youre trying to remove not air
Can you get some sort of inverted canopy so the lift is downwards?
Might stop it trying to fly away but with a bit of an adverse effect on how it deals with rain water. You can get gazebos with a square tower type thing on the top to let the air out (on a hot day
)I guess theyre not much better as it's lift youre trying to remove not air
Can you get some sort of inverted canopy so the lift is downwards?
saaby93 said:
Simpo Two said:
When I saw the title I thought you were planning to cross the Channel on a gazebo...
Nearly did You can get gazebos with a square tower type thing on the top to let the air out (on a hot day
)I guess theyre not much better as it's lift youre trying to remove not air
Can you get some sort of inverted canopy so the lift is downwards?
emicen said:
Might stop it trying to fly away but with a bit of an adverse effect on how it deals with rain water.
You might have something in that - it automatically adopts the inverted canopy shape in the presence of rainwater.So not only does that hold it down the revised aerofoil shape keeps it down too
Minor issue with headroom
saaby93 said:
I guess theyre not much better as it's lift youre trying to remove not air
Can you get some sort of inverted canopy so the lift is downwards?
The hole would allow the pressure differential to reduce so reducing lift, though probably not fast enough to prevent take-off.Can you get some sort of inverted canopy so the lift is downwards?
How about mounting an F1-style spoiler on the top, connected to a weathervane so it always points into the wind?
Gassing Station | Boats, Planes & Trains | Top of Page | What's New | My Stuff