How to build a sturdy shade structure using a military surplus "35 foot" parachute. We're bringing this to Burning Man this year, so it has to withstand the intense winds on the playa.
Update: The structure made it to the playa and survived the wicked windstorm on Wednesday! It required some additional reinforcement, but it held together quite well. Our flag was a little damaged, and the threaded end of the center pole broke when we tried to unscrew it from the coupler after the windstorm. Luckily we had an extra coupler, so we just reversed the pipe and used the other end. Aside from that, no other parts broke or were significantly damaged during the week. Set up went pretty smoothly with a couple people helping. The most time consuming part was screwing the eye bolts into the posts. Next year I think I'm just going to drill the holes out a little wider and use a nut and washer to secure them.
The modifications we made in the field were:
- We opened the structure at two ends to allow breeze through the structure. The parachute was either rolled over the posts or tied up using rope tied around a ball or penny pushed through on the opposite side of the 'chute.
- Several ropes strung over the top of the structure and anchored in the ground to keep the parachute from billowing too much.
- Slits cut in some sections of the parachute to reduce billowing.
- Additional guy ropes run from the top of the posts to the ground on the windward side of the structure. We found that the structure put a lot of strain on the anchored guy ropes when the wind really picked up. Adding additional ropes and rebar helped significantly.
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Step 1: The Plan
The shade structure is built somewhat like a big top tent. There is a large centre pole and six outer posts arranged around the centre pole. The centre pole and outer posts are supported by guy lines that also support the parachute once it is draped over the frame. You'll need to know or learn some knots in order to attach the guy lines correctly.
The centre pole is made from two 6' 1/2" steel pipes. I went with two segments of pipe and a coupler because they will fit in our van more easily than one 12' post or pipe. The outer posts are 8' 4x4s and just fit in our van. The (optional) flag pole on the roof can also be attached with another pipe coupler.
Like any good Burning Man shade structure, all the rope and posts are secured to the ground with rebar.
My cheesy Inkscape-drawn plan is below. For the original size image see here.
Step 2: Materials Needed
- 35' parachute. We found ours at a military surplus store for about $130 CAD.
- ~400' parachute cord. Also available at military surplus stores.
- 6 8' 4x4s
- 24 3/8-16 5" Eye bolts with nuts, eye diameter should be at least 1/2" (a 1/2" piece of rebar should just slide through the eye)
- 24 3/8" washers
Step 3: More Materials
- 7 4' pieces of rebar, 1/2" dia.
- 12 or more 3' rebar "candy canes" (3' section of rebar bent to form a hook)
- sledgehammer for rebar
- 2 6' 1/2" sections of threaded steel pipe
- 1 1/2" pipe coupler
- 1 1/2" pipe tee
Rebar candy canes are much safer when sticking out of the ground. You might stub your toe, but you won't impale your shin. They also make excellent rope tie downs.
To make a candy cane:
1. Insert one end of the rebar into one 1/2" pipe about halfway.
2. Place the pipe and rebar on the ground against your house or a sturdy wall.
3. Slide the other 1/2" pipe over the exposed end of the rebar.
4. Grab the long end of the pipe and bend the rebar over. You may need someone to help you by standing on the rebar as you start bending it.
Step 4: Tools
- safety glasses
- work gloves
- ruler/measuring tape
- center punch
- An assistant. One person could probably do this, but it's much easier with two.
- A couple of short step ladders or chairs.
- wrench for eye bolt nuts
- knife to cut rope
- lighter to burn rope ends
Step 5: Prepare the Posts
Drill two 5/16" holes 2.5" and 5" from the top of each 4x4. Tap the holes by screwing an eye bolt into each. Screwing in the eye bolts is a little easier if you stick something through the eye, like a piece of rebar or another eye bolt. You can see a simple crank I rigged up with some of the extra eye bolts.
Step 6: Prepare the Posts, Continued
Drill two more holes at the opposite end of the post, one 2.5" and one 12" from the end. Again tap the holes by screwing the eye bolts into the holes.
These holes will support the bottom of the posts. The eye bolts will slide over rebar stakes.
Step 7: Rebar Layout
Each post slides over one of the 4' rebar stakes, as does the centre pole. Find a big space in a nearby field, or if you're lucky, in your backyard, and pound in one of the rebar stakes. This will be the centre pole. Pound in the remaining six rebar stakes in a hexagon centred around the central stake. It isn't absolutely critical that you get it perfect, but the stakes should all be 7' from the centre and spaced fairly evenly.
A good way of getting the distances and angles correct is to create an equilateral triangle of rope that is 7' a side. Tie knots at the corners of the triangle and slip the triangle over the centre stake, placing a knot behind the stake. Stretch the triangle out and place rebar at the knots at the corners. Pull the triangle off the rebar and slip it over the centre pole and one of the new stakes. Stretch the triangle out again and place a stake at the remaing free knot in the triangle. Repeat for each new stake. Note that opposite rebar stakes should form a straight line through the centre.
One other thing to note is that you should try and get the rebar as vertical as possible. We weren't too successful with this the first time around so we're going to try making a guide out of a small board, a 1/2" piece of pipe and a 1/2" pipe wall flange. If anyone has any other suggestions please leave a comment!
For a larger version of the second image see here.
Step 8: Add the Posts
Attach the eye bolts to the posts. At the top, screw the eye bolts facing opposite directions. Secure the bolts with a washer and a nut. At the bottom, screw both eye bolts on the same side.
Slide each of the posts over the outer rebar stakes. Pound in a candy cane about 4' behind each post, in a straight line from the centre stake. This is where you'll need to tie some knots. You'll need to know how to tie a clove hitch and a taut line hitch. A clove hitch is useful for attaching a rope to a post or rod. A taut line hitch is an adjustable knot, sort of like the knot equivalent of a locking slider. We're using them here so that we can increase the tension on the structure to straighten it out and to make it more stable. Make sure you know how to tie these correctly! They're pretty handy elsewhere too, so they're worth knowing anyway.
For the upper horizontal sections use about 9' of rope. Tie a clove hitch around one post and secure it with a regular knot (i.e. a half-hitch), wrap the rope around the next post and tie a taut line hitch.
For the guy lines use about 10' or 11' of rope. Tie a clove hitch around the eye bolt secured with another half-hitch and run the rope around the candy cane and tie another taut line hitch.
While we didn't do this the first time through, we plan on adding additional supporting ropes from the top of each post down to the candy canes behind each adjacent post. This provides some lateral stability to each post and holds the parachute out better. These ropes should be about 13.5' long and are tied the same way as the other guy lines (clove hitch around the eye bolt, taut line at the rebar candy cane).
Instead of pre-cutting your rope, it may be easier to measure it in place and cut it to fit. Make sure you burn the cut ends of your cord too so that it doesn't fray.
This step is by far the most time consuming. With two people it shouldn't take more than 20-30 minutes or so, if they know their knots.
Once all the knots are tied, tighten the taut line hitches and try to straighten out the structure. The tighter the better, since the ropes have to support the parachute and eventually they must withstand the 40mph winds on the playa.
Step 9: Parachute!
Attach the pipe coupling to the end of one of the 1/2" pipes and slide the pipe over the central rebar stake. The coupling will prevent the parachute from catching on the pipe.
Unroll the parachute and unfold it in the centre of the structure, over top of the centre pole. Try and stretch it out evenly. Starting with one side, pull the parachute over the top of the posts. This step is probably easier with two people, since the parachute tends to snag a bit on the tops of the posts. Once you get the parachute over one side, work your way around and even out the fabric again.
Step 10: Centre Pole
Measure out and cut six 9' sections of rope. Attach the 1/2" pipe tee to the end of the remaining 6' pipe (note I goofed and grabbed a 1/2" to 3/4" tee because someone mixed up the box at Home Depot, grumble). Pass one end through the tee and tie a bowline to secure the rope.
Duck under the parachute and try to to loop part of the centre of the parachute over the tee so that you can raise the parachute with the pipe. Our parachute had a canvas strap that we were able to fit over the tee that worked pretty well. You may have to improvise a bit here.
Once the centre of the parachute is attached to the pipe, raise it over the existing pipe and screw them together. The structure should be starting to look a little more respectable now.
Separate the ropes dangling from the centre pole and tie them to the eye bolts on the inside of the posts using another taught line hitch. Once all the knots are tied, tighten the hitches to raise the parachute. Again, tighter is better. As you tighten the centre pole ropes you may have to tighten the others to keep everything straight.
Step 11: Entrance
Even out the parachute some more and then roll up one section of the parachute over two of the posts to form an entrance. You can make this permanent if you wish by placing a coin behind the parachute on one side and tying a piece of rope around the coin, passing it over the rolled up fabric, and then tying it to one of the posts or eye bolts.
Pull the parachute out from the structure and secure it to the ground with rebar candy canes (not shown).
I've added a scale bar to the image below. It's six feet tall, to give you an idea of the size of the structure. The high roof makes the structure seem roomy and airy when inside. We had originally hoped to fit our tent inside the structure (when we thought we were actually getting a 35' parachute), but we won't be able to with this smaller 'chute. A long narrow tent might fit as long as it it less than 7' wide. That said, there is easily enough room for five or six chairs, a table, a few totes, and a couple of coolers.
That's it! I'll update this once we bring it to the playa!