Sail potential of portable canopy

Several years ago we bought an inexpensive 12' X 12' portable canopy---one of those tent roof things on spindly legs which folds down into a size which is convenient for storage---but never used it. A few days ago, my wife suggested that we set it up in our front patio area which we never use in the summer because there is no shade. We did, and it's very nice there.

I realized that it will be exposed to the wind, and there is no point securing the legs to the small pavers on the patio. For now, I have a couple of pyramid blocks sitting on the feet. I intend to cast some concrete blocks with bolts sticking up which match the hole pattern in the canopy's feet, but I have no idea of how to determine how much weight I need to make it stable in a wind. Can anyone direct me to a formula I can use to calculate for this situation?

Thanks, Stan

There is no formula for something like that, too many variables to consider.

For your own safety, and the neighbors if you have any, best to take it down and store it when it's not in use.

If you're in the city limits, it's probably illegal to put it in as a permanent shelter. Most cities have passed ordinances against them . They tend to damage other peoples property and fly into power lines.

Stan,

You're looking at it the wrong way. It's not how much lift the canopy can create, it's how much lift it can create before it rips or the frame breaks. You could of course do a destructive test to see how hard you can pull the canvas before it rips, then go buy another one, but I suspect you have a pretty good idea just by looking at it how much strain the stitches can handle. If you think it can sustain a 200 lb pull, then you need four fifty pound weights to hold it down.

For several years my wife had a craft business and would set up a 10'x10' canopy at weekend craft shows. I tagged along and did what I was told. It was a perfect relationship for the craft shows. But I digress. Canopies like ours, and yours, can lift off the ground sometimes with very little wind - acting like an aircraft wing. We secured ours to the earth with tent stakes driven into the ground at an acute angle. On pavement we had concrete-filled coffee cans with an I-bolt set in the concrete to secure the canopy. Each tent stake should be set a couple of feet away from the legs to hold it somewhat steady in a strong wind. If the stakes are set right next to the legs, the canopy will normally stay put but a wind will wobble and shake it. There was nothing scientific about our setup and we never had our canopy sail away. We did see other canopies that were not secured well rise up in a wind and usually flip upside down.

A big problem on the beach here . Easily sorted if the canopy has a tubular steel frame . Thread strong nylon cord through the frame and let a decent length hang out . Tie these ends to your weights , we use sand bags . The advantage of this is that the load is distributed all around the frame . It won't stop the cover being torn off though ! :shock:

Yep they can fly away! I was at the EAA Airventure a few years ago. We had a screened canopy set up with out table and chairs coolers and what not and each family in our group had a tent or pop-up camper. A storm blows in one night I look out the window expecting to see crumpled canopy, instead that sucker was GONE!! Run out side and grab everything left behind and stash it in the back of a pick-up with a topper, HMMM, no sign of the canopy, I go back to bed. I wake up at about 5:30 AM and start looking, our canopy was wrapped around the front of a 5th wheel trailer across the way and a half block down. I gathered it up and drug it back to camp, it took some structural damage, tubes bent and the funny little corner brackets broken. I was thinking about pitching it in the dumpster and coming back next year to see if it got made into an ultra-lite. Later that morning I walked the 1/4 of a mile to the shower and saw quite a few canopies and RV awnings that weren't where they belonged. One awning came loose and beat up the trailer pretty bad.

for a moderate wind figure 20 psf acting on the exposed area. compute the bending moment of that area about the bottom of the legs on that side--i assume two legs.
the weight needed for the 2 legs will be the bending moment divided by the distance across to the other 2 downwind legs
and if the wind comes from the other side they will need the weights also.

Stan......a bunch of years I purchased one of those 10'x10' canopies that have the tublar frame and legs in the kit.

I figured the canopy would be great at a job site that I got the bid for new refrigeration equipment.

I figgered that I should get myself familiar with the setting-up of the frame and I chose the front yard to get some practice.

Well, I had the frame all set and next came the tarp (roof) and all of those bungie cords.

Project complete. Went into the house for a cup of coffee and to do some paperwork.

I returned in about 1/2 hr. to the canopy. I noticed a thunderstorm was coming from the WEST. So, I started to put stakes in the ground to hold things down.

By the time I could get the 2nd stake in the ground, a "MICRO BURST" started to lift the whole rig. I grabbed the one side "upwind" and was actually lifted off the ground about 4-5 ft.

I let go of the canopy and it blew into the neighbor's house and caused about $1,500.00 worth of damage to his newely vinyl siding job.

Thank goodness for my "homeowner's" liability insurance.

Moral to the story.....the temporary canopy, sufficiently weighted down with approximately 75# worth of concrete loaded into approximately 4 ft lengths of 4 inch PVC pipe should be enough weight at each corner.

I still use the orig. canopy at construction sites. Keeps the area a lot cooler. Especially when up on roofs.

HTH John,PA

Wow! I'm glad I asked.

Putting together information from answers I've received here, I've decided that I would be better off working on a way to let the top slip off the frame at less than gale force wind velocity. If I can do that, and tether it so that once it comes off the frame and collapses it won't blow off the property and land on the windshield of a limousine of visiting tort lawyers, I might be better off than trying to get enough weight on it to hold it down.

Thanks, everybody.

Stan

I figgered out the same thing.

Let us know what you come up with. Sorta gett'N ready to do a yard sale in the
"FRONT YARD".

John,PA

I simply replaced the heavy duty bungies with some cheap cotton string tied to the tarp and the tubular frame. So far, it has worked great!

I and some other church folks helped our preacher put up a carport sized canopy. He tied it to an adjacent chain link fence with 1/4" nylon rope, against all of our warnings. Added more rope ties when we complained. It lasted a few nice balmy days, then one night when it was about a week old, a heavy wind took the whole mess and scattered it across the neighborhood. We actually cut down a sweet gum tree to get part of the wreckage down - luckily it was on his property. It's very hard to help someone who is convinced that he's the smartest man on the planet.

You'll get about a season out of it leaving it out there all the time.

What mkirsch said. Between sun and wind the cover will probably be in tatters by the end of the season. At least you get some use out of it though.