So not car related question. How much lift can a 10x12 patio canopy generate?

[Larry Callahan]

I plan to put the legs of a new 10x12 patio canopy into flower pots and to pour them half full of concrete.

For the life of me I can't find a site with any info on how much lift might be generated on a windy day. Over the years we have lost a few to the wind.

What would be sufficient to hold it down? 50lbs at each corner? 100lbs?

[Protour_Pinto]

I usually put the legs into 5gal buckets and fill them half way with cement. A small hose to the bottom for water drainage and fill the rest of the way with soil and plant flowers in them.

[Vicinity]

I had a 12x12 to cover (most) of my car, and I had about 20lbs of weight on each corner, a very windy day took it over the car and half across a field. So that's a starting point. :)

My recommendation is use as much weight as you can. Overkill is better than a scrap canopy.

[Twentyover]

Depends on wind speed. "Windy day" and "very windy day" used are hardly objective criteria for evaluating lift.

Google Bernoulli's Equation

[baz67]

While it is true you can make about anything create a lifting force, I do not think lift is the problem with covers. I would guess the covers act more like a sail than a wing. However, here is the lift equation L = .5 * Cl * r * V^2 * A. The lift equation states that lift is equal to the lift coefficient (Cl) times the density of the air (r) times half of the square of the velocity (V) times the wing area (A). Have fun Larry.

[Larry Callahan]

While it is true you can make about anything create a lifting force, I do not think lift is the problem with covers. I would guess the covers act more like a sail than a wing. However, here is the lift equation L = .5 * Cl * r * V^2 * A. The lift equation states that lift is equal to the lift coefficient (Cl) times the density of the air (r) times half of the square of the velocity (V) times the wing area (A). Have fun Larry.

Oh gee thanks.. Now my head hurts. LOL!

[shmoov69]

Don't you work in the aerospace industry or something Larry? LOL! I'd say that 50lbs on the corners should be WAAAY sufficient to keep it from moving. Really, if 200lbs won't keep it down, it will prolly be torn up from the wind anyway.

Disclaimer, this is coming from a roofer not an engineer that can even figure out that equation Brian posted!! LOL!!

[CarlC]

The Cl and area are both variable since the shape of the wing is always changing. Hence, setting up a spreadsheet with tables for 1) Variable area, 2) Variable Cl, and 3) Variable air density, should yeild somewhere in the neighborhood of 12,362,987,108,223 possible combinations.

Or, if there is soil under the flower pots, just sink rods into the ground through the bottom of the pots and attach them to the canopy legs.

[Jim Nilsen]

When the wind blows in Wisconsin at the Jefferson swapmeet it creates a lot of havoc with the tarp setups and the ez n ups. You are usually good to about 15 - 20 mph with 20 -30 lbs on each corner. When the wind starts to get to 25-30 mph gust I have seen 50 at each corner barely work. At 35- 40mph gust you better have a 100 lb person each corner with a good grip and hope for the best, the tarp will usually try to vacate the frame at that point which at least reduces the damage the frame can cause. I have seen some setups fly like an ultralight and do some nasty scrtch and dent damage to a few cars that got in the way.

5 gal buckets full of cement usually do about as good as it gets and after that the setups usually start to bend and break along with ripping somewhere if the are old. Taking the cover off the frame is usually the only way to avoid any problems once the wind gets over 25 mph.

Tent stakes work if the are big and deep enough but I have seen them get pulled right out of the ground. You almost have to go to the stakes the size of the commercial size tents for parties that you pay big money to rent. Putting some cement in the ground or something substantial like some steel with a good hook might be a better option.

Goodluck Larry.

[Bryce]

http://www.chamberlinltd.com/en/articles/printview.asp?37

These guys use 15psi for hurricane winds

Google hurricane winds vs pressure and extrapolate down to a wind speed you will likely see.

[blakes72x]

i set up tents and work sometimes for events and i know for a 10x10 tent outdoors we use a 100lb weight at each corner attached to the tent frame with a comealong strap on a windy day to ensure it doesn't take off otherwise we use 50lb sand bags or nothing if its indoors

[claytonisbob]

Square the max wind speed you'd expect and multiply by by 0.00256. That's your lbs force per square foot. Canopy is ~ 120 sq ft assuming it's not a totally flat surface.

So like for 25mph winds you'd have:
25^2 = 625
625 * 0.00256 = 1.6 lbs/sq ft
1.6 * 120 = 192 lbs/sq ft of force.

So if you're expecting no more than 25 mph winds, 50lbs per corner should be sufficient. The cool thing though is that is easily going to be overkill since wind will likely never be hitting directly right at the whole 10x12. It would be rushing over it, hitting the sides, and probably whip under it some. Wind could also be over 25mph, but I think 50 lbs should probably be good enough.